Machines

13 pages, 2045 KiB

Open AccessEditor’s ChoiceArticle

Thermodynamic Performance Analysis of Solar Based Organic Rankine Cycle Coupled with Thermal Storage for a Semi-Arid Climate

by Nasser Mohammed A. Almefreji, Babras Khan and Man-Hoe Kim

Machines 2021, 9(5), 88; https://doi.org/10.3390/machines9050088 - 28 Apr 2021

Cited by 5 | Viewed by 2904

Abstract

This study focuses on the thermodynamic performance analysis of the solar organic Rankine cycle (SORC) that uses solar radiation over a moderate temperature range. A compound parabolic collector (CPC) was adjusted to collect solar radiation because of its long-lasting nature and featured low [...] Read more.

This study focuses on the thermodynamic performance analysis of the solar organic Rankine cycle (SORC) that uses solar radiation over a moderate temperature range. A compound parabolic collector (CPC) was adjusted to collect solar radiation because of its long-lasting nature and featured low concentration ratios, which are favorable for moderate temperature applications. A thermal storage tank was fixed to preserve the solar energy and ensure the system’s continuous performance during unfavorable weather. However, water was used as the heat transfer fluid and R245fa was used as the working fluid in this system. The performance in both the hottest and coldest months was analyzed using the average hourly profile in MATLAB using weather data from Riyadh, Saudi Arabia. Variations in the tank temperature during the charging and discharging modes were found. The hourly based thermal efficiency and net power output for both configurations were also compared. The results show that at 17:00, when the cycle was about to shut down, the thermal efficiency was 12.79% and the network output was 16 kW in July, whereas in January, the efficiency was ~12.80% and the net power output was 15.54 kW. Full article

(This article belongs to the Section Electromechanical Energy Conversion Systems)

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15 pages, 6643 KiB

Open AccessEditor’s ChoiceArticle

Multiscale Modelling and Analysis for Design and Development of a High-Precision Aerostatic Bearing Slideway and Its Digital Twin

by Ning Gou, Kai Cheng and Dehong Huo

Machines 2021, 9(5), 85; https://doi.org/10.3390/machines9050085 - 25 Apr 2021

Cited by 12 | Viewed by 3373

Abstract

Aerostatic bearing slideways have been increasingly applied in the precision engineering industry and other high-tech sectors over the last two decades or so, due to their considerable advantages over mechanical slideways in terms of high motion accuracy, high speeds, low friction, and environment-friendly [...] Read more.

Aerostatic bearing slideways have been increasingly applied in the precision engineering industry and other high-tech sectors over the last two decades or so, due to their considerable advantages over mechanical slideways in terms of high motion accuracy, high speeds, low friction, and environment-friendly operations. However, new challenges in air bearings design and analysis have been occurring and often imposed along the journeys. An industrial-feasible approach for the design and development of aerostatic bearing slideways as standard engineering products is essential and much needed particularly for addressing their rapid demands in diverse precision engineering sectors, and better applications and services in a continuous sustainable manner. This paper presents the multiscale modelling and analysis-based approach for design and development of the aerostatic bearing slideways and its digital twin. The multiscale modelling and analysis and the associated simulation development can be the kernel of the digital twin, which cover the mechanical design, direct drive and control, dynamics tuning of the slideway, and their entire mechatronic system integration. Using this approach and implementation, the performance of an aerostatic bearing slideway can be predicted and assessed in the process. The implementation perspectives for the sideway digital twin are presented and discussed in steps. The digital simulations and digital twin system can be fundamentally important for continuously improving the design and development of aerostatic bearing slideways, and their applications and services in the context of industry 4.0 and beyond. Full article

(This article belongs to the Special Issue Advanced Autonomous Machines and Designs)

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14 pages, 31448 KiB

Open AccessEditor’s ChoiceArticle

Development of a New Finishing Process Combining a Fixed Abrasive Polishing with Magnetic Abrasive Finishing Process

by Yanhua Zou, Ryunosuke Satou, Ozora Yamazaki and Huijun Xie

Machines 2021, 9(4), 81; https://doi.org/10.3390/machines9040081 - 12 Apr 2021

Cited by 12 | Viewed by 3989

Abstract

High quality, highly efficient finishing processes are required for finishing difficult-to-machine materials. Magnetic abrasive finishing (MAF) process is a finishing method that can obtain a high accuracy surface using fine magnetic particles and abrasive particles, but has poor finishing efficiency. On the contrary, [...] Read more.

High quality, highly efficient finishing processes are required for finishing difficult-to-machine materials. Magnetic abrasive finishing (MAF) process is a finishing method that can obtain a high accuracy surface using fine magnetic particles and abrasive particles, but has poor finishing efficiency. On the contrary, fixed abrasive polishing (FAP) is a polishing process can obtain high material removal efficiency but often cannot provide a high-quality surface at the nano-scale. Therefore, this work proposes a new finishing process, which combines the magnetic abrasive finishing process and the fixed abrasive polishing process (MAF-FAP). To verify the proposed methodology, a finishing device was developed and finishing experiments on alumina ceramic plates were performed. Furthermore, the mechanism of the MAF-FAP process was investigated. In addition, the influence of process parameters on finishing characteristics is discussed. According to the experimental results, this process can achieve high-efficiency finishing of brittle hard materials (alumina ceramics) and can obtain nano-scale surfaces. The surface roughness of the alumina ceramic plate is improved from 202.11 nm Ra to 3.67 nm Ra within 30 min. Full article

(This article belongs to the Special Issue Advances and Trends in Non-conventional, Abrasive and Precision Machining 2021)

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19 pages, 3684 KiB

Open AccessEditor’s ChoiceArticle

Cybersecurity Risk Assessment in Smart City Infrastructures

by Maxim Kalinin, Vasiliy Krundyshev and Peter Zegzhda

Machines 2021, 9(4), 78; https://doi.org/10.3390/machines9040078 - 04 Apr 2021

Cited by 51 | Viewed by 9892

Abstract

The article is devoted to cybersecurity risk assessment of the dynamic device-to-device networks of a smart city. Analysis of the modern security threats at the IoT/IIoT, VANET, and WSN inter-device infrastructures demonstrates that the main concern is a set of network security threats [...] Read more.

The article is devoted to cybersecurity risk assessment of the dynamic device-to-device networks of a smart city. Analysis of the modern security threats at the IoT/IIoT, VANET, and WSN inter-device infrastructures demonstrates that the main concern is a set of network security threats targeted at the functional sustainability of smart urban infrastructure, the most common use case of smart networks. As a result of our study, systematization of the existing cybersecurity risk assessment methods has been provided. Expert-based risk assessment and active human participation cannot be provided for the huge, complex, and permanently changing digital environment of the smart city. The methods of scenario analysis and functional analysis are specific to industrial risk management and are hardly adaptable to solving cybersecurity tasks. The statistical risk evaluation methods force us to collect statistical data for the calculation of the security indicators for the self-organizing networks, and the accuracy of this method depends on the number of calculating iterations. In our work, we have proposed a new approach for cybersecurity risk management based on object typing, data mining, and quantitative risk assessment for the smart city infrastructure. The experimental study has shown us that the artificial neural network allows us to automatically, unambiguously, and reasonably assess the cyber risk for various object types in the dynamic digital infrastructures of the smart city. Full article

(This article belongs to the Special Issue Mechatronic System for Automatic Control)

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20 pages, 7884 KiB

Open AccessEditor’s ChoiceArticle

Optimal Control of the Positional Electric Drive and Its Implementation

by Vladimir Dotsenko, Roman Prokudin and Alexander Litvinenko

Machines 2021, 9(4), 70; https://doi.org/10.3390/machines9040070 - 24 Mar 2021

Cited by 2 | Viewed by 1806

Abstract

The article deals with the optimal control of the positional electric drive of the stator element of a segment-type wind turbine. The calculation options charts current in the assumption of the minimum energy consumption and the implementation of line chart current using the [...] Read more.

The article deals with the optimal control of the positional electric drive of the stator element of a segment-type wind turbine. The calculation options charts current in the assumption of the minimum energy consumption and the implementation of line chart current using the phenomenon of capacitor discharge. The analysis of the implementation is expressed in a jump-like change in current and a triangular graph of the speed change. This article deals with small capacity synchronous wind turbine generators with a segment type stator. These units have the possibility of intentionally changing the air gap between the rotor and stator. This allows: (1) Reduce the starting torque on the rotor shaft, which will allow the rotor to pick up at low wind speeds. (2) Equivalent to change of air gap in this case is change of excitation of synchronous generators. Thus, the purpose of the article is to consider a method of excitation of generators in a segmented design, by controlling the gap with the electric drive, while providing control should be carried out with minimal losses. Full article

(This article belongs to the Special Issue Mechatronic System for Automatic Control)

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23 pages, 8318 KiB

Open AccessEditor’s ChoiceArticle

Design and Optimization of a Centrifugal Pump for Slurry Transport Using the Response Surface Method

by Khaled Alawadhi, Bashar Alzuwayer, Tareq Ali Mohammad and Mohammad H. Buhemdi

Machines 2021, 9(3), 60; https://doi.org/10.3390/machines9030060 - 13 Mar 2021

Cited by 17 | Viewed by 6326

Abstract

Since centrifugal pumps consume a mammoth amount of energy in various industrial applications, their design and optimization are highly relevant to saving maximum energy and increasing the system’s efficiency. In the current investigation, a centrifugal pump has been designed and optimized. The study [...] Read more.

Since centrifugal pumps consume a mammoth amount of energy in various industrial applications, their design and optimization are highly relevant to saving maximum energy and increasing the system’s efficiency. In the current investigation, a centrifugal pump has been designed and optimized. The study has been carried out for the specific application of transportation of slurry at a flow rate of 120 m³/hr to a head of 20 m. For the optimization process, a multi-objective genetic algorithm (MOGA) and response surface methodology (RSM) have been employed. The process is based on the mean line design of the pump. It utilizes six geometric parameters as design variables, i.e., number of vanes, inlet beta shroud, exit beta shroud, hub inlet blade draft, Rake angle, and the impeller’s rotational speed. The objective functions employed are pump power, hydraulic efficiency, volumetric efficiency, and pump efficiency. In this reference, five different software packages, i.e., ANSYS Vista, ANSYS DesignModeler, response surface optimization software, and ANSYS CFX, were coupled to achieve the optimized design of the pump geometry. Characteristic maps were generated using simulations conducted for 45 points. Additionally, erosion rate was predicted using 3-D numerical simulations under various conditions. Finally, the transient behavior of the pump, being the highlight of the study, was evaluated. Results suggest that the maximum fluctuation in the local pressure and stresses on the cases correspond to a phase angle of 0°–30° of the casing that in turn corresponds to the maximum erosion rates in the region. Full article

(This article belongs to the Section Machine Design and Theory)

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13 pages, 1188 KiB

Open AccessEditor’s ChoiceArticle

Aeroelastic Response of Aircraft Wings to External Store Separation Using Flexible Multibody Dynamics

by Aykut Tamer

Machines 2021, 9(3), 61; https://doi.org/10.3390/machines9030061 - 13 Mar 2021

Cited by 2 | Viewed by 2678

Abstract

In aviation, using external stores under the wings is a common method of carrying payload or fuel. In some cases, the payload can be rigidly attached to the wing. However, stores must often be ejected during flight for aircraft, such as military type, [...] Read more.

In aviation, using external stores under the wings is a common method of carrying payload or fuel. In some cases, the payload can be rigidly attached to the wing. However, stores must often be ejected during flight for aircraft, such as military type, which carry drop tanks and missiles. This may cause the wing to respond dynamically with increasing amplitudes, due to the impulsive load of ejection and the change of total mass. This is especially critical in aircraft with highly flexible wings, such as those with high aspect ratios. In this case, it is crucial to evaluate the wing response to store separation, which requires a suitable simulation environment that is able to support nonlinear and multidisciplinary analysis. To address such a need, this work presents the use of flexible multibody dynamics in the simulation of wing response to store separation. To demonstrate, a highly compliant wing was selected with a rigid body that was mounted on the wing to represent an external store. The time marching simulation of the wing before and after the store separation was presented to show the features and benefits of the method. Full article

(This article belongs to the Special Issue Dynamic Stability Analysis of Aerospace Structures)

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17 pages, 872 KiB

Open AccessEditor’s ChoiceArticle

Application of the Sequence Planner Control Framework to an Intelligent Automation System with a Focus on Error Handling

by Martin Dahl, Kristofer Bengtsson and Petter Falkman

Machines 2021, 9(3), 59; https://doi.org/10.3390/machines9030059 - 12 Mar 2021

Cited by 8 | Viewed by 2010

Abstract

Future automation systems are likely to include devices with a varying degree of autonomy, as well as advanced algorithms for perception and control. Human operators will be expected to work side by side with both collaborative robots performing assembly tasks and roaming robots [...] Read more.

Future automation systems are likely to include devices with a varying degree of autonomy, as well as advanced algorithms for perception and control. Human operators will be expected to work side by side with both collaborative robots performing assembly tasks and roaming robots that handle material transport. To maintain the flexibility provided by human operators when introducing such robots, these autonomous robots need to be intelligently coordinated, i.e., they need to be supported by an intelligent automation system. One challenge in developing intelligent automation systems is handling the large amount of possible error situations that can arise due to the volatile and sometimes unpredictable nature of the environment. Sequence Planner is a control framework that supports the development of intelligent automation systems. This paper describes Sequence Planner and tests its ability to handle errors that arise during execution of an intelligent automation system. An automation system, developed using Sequence Planner, is subjected to a number of scenarios where errors occur. The error scenarios and experimental results are presented along with a discussion of the experience gained in trying to achieve robust intelligent automation. Full article

(This article belongs to the Special Issue Mechatronic System for Automatic Control)

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16 pages, 5771 KiB

Open AccessEditor’s ChoiceArticle

Dual-Motor Planetary Transmission to Improve Efficiency in Electric Vehicles

by Giacomo Mantriota and Giulio Reina

Machines 2021, 9(3), 58; https://doi.org/10.3390/machines9030058 - 11 Mar 2021

Cited by 30 | Viewed by 6264

Abstract

Electric cars are typically subject to highly variable operational conditions, especially when they drive in urban environments. Consequently, the efficiency of the electric motors may degrade significantly, possibly leading to lower autonomy and higher running costs. Latest advances in power electronics and motion [...] Read more.

Electric cars are typically subject to highly variable operational conditions, especially when they drive in urban environments. Consequently, the efficiency of the electric motors may degrade significantly, possibly leading to lower autonomy and higher running costs. Latest advances in power electronics and motion control have paved the way to the development of novel architectures of full electric power transmissions. In this paper, a dual-motor solution is proposed where two smaller motors are coupled via a planetary gear, in contrast to the standard configuration that uses one larger motor directly connected to the drive wheels with a fixed ratio reducer. The dual-motor architecture guarantees that both motors operate in the vicinity of their optimal working range, resulting in a higher overall energy efficiency. The technical requirements and the control strategy of the dual-motor system are selected through a parametric optimization process. Results included were obtained from extensive simulations performed over different standard driving cycles, showing that the dual-motor power transmission generally outperforms the single-motor counterpart with an average efficiency improvement of about 9% that is reached in both the power delivery and regeneration stage. Full article

(This article belongs to the Special Issue Italian Advances on MMS)

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18 pages, 2499 KiB

Open AccessEditor’s ChoiceArticle

Valve Deadzone/Backlash Compensation for Lifting Motion Control of Hydraulic Manipulators

by Lan Li, Ziying Lin, Yi Jiang, Cungui Yu and Jianyong Yao

Machines 2021, 9(3), 57; https://doi.org/10.3390/machines9030057 - 08 Mar 2021

Cited by 11 | Viewed by 2841

Abstract

In this paper, a novel nonlinear model and high-precision lifting motion control method of a hydraulic manipulator driven by a proportional valve are presented, with consideration of severe system nonlinearities, various uncertainties as well as valve backlash/deadzone input nonlinearities. To accomplish this mission, [...] Read more.

In this paper, a novel nonlinear model and high-precision lifting motion control method of a hydraulic manipulator driven by a proportional valve are presented, with consideration of severe system nonlinearities, various uncertainties as well as valve backlash/deadzone input nonlinearities. To accomplish this mission, based on the independent valve orifice throttling process, a new comprehensive pressure-flow model is proposed to uniformly indicate both the backlash and deadzone effects on the flow characteristics. Furthermore, in the manipulator lifting dynamics, considering mechanism nonlinearity and utilizing a smooth LuGre friction model to describe the friction dynamics, a nonlinear state-space mathematical model of hydraulic manipulation system is then established. To suppress the adverse effects of severe nonlinearities and uncertainties in the system, a high precision adaptive robust control method is proposed via backstepping, in which a projection-type adaptive law in combination with a robust feedback term is conducted to attenuate various uncertainties and disturbances. Lyapunov stability analysis demonstrates that the proposed control scheme can acquire transient and steady-state close-loop stability, and the excellent tracking performance of the designed control law is verified by comparative simulation results. Full article

(This article belongs to the Special Issue Advanced Control of Industrial Electro-Hydraulic Systems)

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16 pages, 4143 KiB

Open AccessEditor’s ChoiceArticle

On the Suspension Design of Paquitop, a Novel Service Robot for Home Assistance Applications

by Luigi Tagliavini, Andrea Botta, Paride Cavallone, Luca Carbonari and Giuseppe Quaglia

Machines 2021, 9(3), 52; https://doi.org/10.3390/machines9030052 - 02 Mar 2021

Cited by 10 | Viewed by 3223

Abstract

The general and constant ageing of the world population that has been observed in the last decade has led robotics researchers community to focus its aims to answer the ever-growing demand for health care, housing, care-giving, and social security. Among others, the researchers [...] Read more.

The general and constant ageing of the world population that has been observed in the last decade has led robotics researchers community to focus its aims to answer the ever-growing demand for health care, housing, care-giving, and social security. Among others, the researchers at Politecnico di Torino are developing a novel platform to enhance the performance offered by present-day issues, and to assess many others which were not even taken into consideration before they have been highlighted by the pandemic emergency currently in progress. This situation, in fact, made dramatically clear how important it is to have reliable non-human operators whom one can trust when the life of elderly or weak patients is endangered by the simple presence of other people. The platform, named Paquitop, features an innovative architecture conceived for omni-directional planar motion. The machine is designed for domestic, unstructured, and variously populated environments. Therefore, the mobile robot should be able to avoid or pass over small obstacles, passing through the capability to achieve specific person tracking tasks, and arriving to the need of operating with an high dynamic performance. Given its purpose, this work addresses the design of the suspension system which enables the platform to ensure a steady floor contact and adequate stability in every using condition. Different configurations of such system are then presented and compared through use-case simulations. Full article

(This article belongs to the Special Issue Latest Trends of Autonomous Aerial and Terrestrial Vehicles for Service Robotics Applications)

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16 pages, 4842 KiB

Open AccessEditor’s ChoiceArticle

Developing New Thermal Protection Method for AC Electric Motors

by Igor V. Bochkarev, Ivan V. Bryakin, Vadim R. Khramshin, Aida R. Sandybaeva and Konstantin V. Litsin

Machines 2021, 9(3), 51; https://doi.org/10.3390/machines9030051 - 01 Mar 2021

Cited by 7 | Viewed by 2604

Abstract

Monitoring the thermal state of windings of electrical machines is a backbone for protection from unacceptable overheating. A large number of different methods and systems aim to solve this problem. This article discusses the main known methods of thermal protection of electric motors [...] Read more.

Monitoring the thermal state of windings of electrical machines is a backbone for protection from unacceptable overheating. A large number of different methods and systems aim to solve this problem. This article discusses the main known methods of thermal protection of electric motors and provides their comparative analysis. This paper shows that the most promising methods are those based on control of the current active resistance of the stator winding, as its value uniquely depends on temperature. It is demonstrated that the known methods have a number of disadvantages. A new phase method for thermal protection of AC motors is proposed. The method is based on the fact that a temperature-induced change in the active and reactive components of the winding impedance causes a corresponding change in the angle between the vectors of phase voltages and currents. This allows for thermal protection by controlling the change in this angle. This article provides tabular analytical substantiation of the proposed method, which is based on the direct measurements of voltage and current and the subsequent algorithmic calculation of physical values functionally related to the sought angle. The authors develop a structural block diagram of a device that implements the proposed thermal protection method. All relevant experimental studies were carried out. In this case, a small-sized electronic thermometer with a remote digital temperature sensor connected to the USB port of a personal computer was used as a temperature meter. The results obtained confirm the functional capability and efficiency of the proposed technical solution. Full article

(This article belongs to the Special Issue Mechatronic System for Automatic Control)

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18 pages, 2747 KiB

Open AccessEditor’s ChoiceArticle

Design of Nonlinear Control of Gas Turbine Engine Based on Constant Eigenvectors

by Sagit Valeev and Natalya Kondratyeva

Machines 2021, 9(3), 49; https://doi.org/10.3390/machines9030049 - 25 Feb 2021

Cited by 5 | Viewed by 5906

Abstract

A gas turbine engine represents a complex dynamic control object. Its characteristics change depending on the state of the environment and the regimes of its operation. This paper discusses an algorithmic approach to the design of a nonlinear controller, based on the concept [...] Read more.

A gas turbine engine represents a complex dynamic control object. Its characteristics change depending on the state of the environment and the regimes of its operation. This paper discusses an algorithmic approach to the design of a nonlinear controller, based on the concept of constant eigenvectors and analytical design of the control system. The proposed design method makes it possible to ensure the stability and the required quality of transient processes at different acceleration modes. In this case, the constancy of the matrix of the canonical basis of the closed-loop control system is assumed, which guarantees stability. The design of a neural network dynamic model of a gas turbine engine based on a neural network approximator with one input and multiple outputs is considered. An example of the design of a nonlinear controller for a gas turbine engine is considered, the neural network model of which is given in the state space. The application of neural network approximation of controller coefficients is presented. Full article

(This article belongs to the Special Issue Mechatronic System for Automatic Control)

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17 pages, 3842 KiB

Open AccessEditor’s ChoiceArticle

Consideration of Distinguishing Design Features of Gas-Turbine and Gas-Reciprocating Units in Design of Emergency Control Systems

by Pavel Ilyushin, Aleksandr Kulikov, Konstantin Suslov and Sergey Filippov

Machines 2021, 9(3), 47; https://doi.org/10.3390/machines9030047 - 24 Feb 2021

Cited by 25 | Viewed by 2281

Abstract

Modern gas-turbine units (GTUs) and gas-reciprocating units (GRUs) have found a wide use at power plants, including distributed generation facilities, running on gaseous fuel. The design features of these generating units have a considerable effect on the nature and parameters of transient processes [...] Read more.

Modern gas-turbine units (GTUs) and gas-reciprocating units (GRUs) have found a wide use at power plants, including distributed generation facilities, running on gaseous fuel. The design features of these generating units have a considerable effect on the nature and parameters of transient processes due to emergency disturbances in the adjacent network. The study shows that single-shaft gas-turbine and gas-reciprocating units do not allow even short-term considerable frequency drops. These schemes and operating conditions arise due to emergency active power shortages when the connection between the power plant and the power system weakens due to repair conditions or islanded operation. The paper presents the results of transient process calculations for operating power plants (distributed generation facilities), which make it possible to identify the unfavorable properties of GTUs and GRUs. The results show that two-shaft (three-shaft) GTUs and GRUs can switch to out-of-step conditions even when short-circuits in the adjacent network are cleared with high-speed relay protection devices. The features of out-of-step conditions and the admissibility of their short-term duration for the spontaneous restoration of generators’ synchronization are considered. The findings suggest that considering the fundamental design features of generating units provides informed technical decisions on equipping power plants (distributed generation (DG) facilities) and the adjacent network with efficient emergency control systems. Full article

(This article belongs to the Special Issue Mechatronic System for Automatic Control)

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24 pages, 2800 KiB

Open AccessEditor’s ChoiceArticle

Segmented Embedded Rapid Defect Detection Method for Bearing Surface Defects

by Linjian Lei, Shengli Sun, Yue Zhang, Huikai Liu and Hui Xie

Machines 2021, 9(2), 40; https://doi.org/10.3390/machines9020040 - 14 Feb 2021

Cited by 9 | Viewed by 2496

Abstract

The rapid development of machine vision has prompted the continuous emergence of new detection systems and algorithms in surface defect detection. However, most of the existing methods establish their systems with few comparisons and verifications, and the methods described still have various problems. [...] Read more.

The rapid development of machine vision has prompted the continuous emergence of new detection systems and algorithms in surface defect detection. However, most of the existing methods establish their systems with few comparisons and verifications, and the methods described still have various problems. Thus, an original defect detection method: Segmented Embedded Rapid Defect Detection Method for Surface Defects (SERDD) is proposed in this paper. This method realizes the two-way fusion of image processing and defect detection, which can efficiently and accurately detect surface defects such as depression, scratches, notches, oil, shallow characters, abnormal dimensions, etc. Besides, the character recognition method based on Spatial Pyramid Character Proportion Matching (SPCPM) is used to identify the engraved characters on the bearing dust cover. Moreover, the problem of characters being cut in coordinate transformation is solved through Image Self-Stitching-and-Cropping (ISSC). This paper adopts adequate real image data to verify and compare the methods and proves the effectiveness and advancement through detection accuracy, missing alarm rate, and false alarm rate. This method can provide machine vision technical support for bearing surface defect detection in its real sense. Full article

(This article belongs to the Section Machines Testing and Maintenance)

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27 pages, 8982 KiB

Open AccessEditor’s ChoiceArticle

Probabilistic Condition Monitoring of Azimuth Thrusters Based on Acceleration Measurements

by Riku-Pekka Nikula, Mika Ruusunen, Joni Keski-Rahkonen, Lars Saarinen and Fredrik Fagerholm

Machines 2021, 9(2), 39; https://doi.org/10.3390/machines9020039 - 10 Feb 2021

Cited by 4 | Viewed by 5231

Abstract

Drill ships and offshore rigs use azimuth thrusters for propulsion, maneuvering and steering, attitude control and dynamic positioning activities. The versatile operating modes and the challenging marine environment create demand for flexible and practical condition monitoring solutions onboard. This study introduces a condition [...] Read more.

Drill ships and offshore rigs use azimuth thrusters for propulsion, maneuvering and steering, attitude control and dynamic positioning activities. The versatile operating modes and the challenging marine environment create demand for flexible and practical condition monitoring solutions onboard. This study introduces a condition monitoring algorithm using acceleration and shaft speed data to detect anomalies that give information on the defects in the driveline components of the thrusters. Statistical features of vibration are predicted with linear regression models and the residuals are then monitored relative to multivariate normal distributions. The method includes an automated shaft speed selection approach that identifies the normal distributed operational areas from the training data based on the residuals. During monitoring, the squared Mahalanobis distance to the identified distributions is calculated in the defined shaft speed ranges, providing information on the thruster condition. The performance of the method was validated based on data from two operating thrusters and compared with reference classifiers. The results suggest that the method could detect changes in the condition of the thrusters during online monitoring. Moreover, it had high accuracy in the bearing condition related binary classification tests. In conclusion, the algorithm has practical properties that exhibit suitability for online application. Full article

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23 pages, 8684 KiB

Open AccessEditor’s ChoiceArticle

Analytical Study on the Cornering Behavior of an Articulated Tracked Vehicle

by Antonio Tota, Enrico Galvagno and Mauro Velardocchia

Machines 2021, 9(2), 38; https://doi.org/10.3390/machines9020038 - 09 Feb 2021

Cited by 13 | Viewed by 3081

Abstract

Articulated tracked vehicles have been traditionally studied and appreciated for the extreme maneuverability and mobility flexibility in terms of grade and side slope capabilities. The articulation joint represents an attractive and advantageous solution, if compared to the traditional skid steering operation, by avoiding [...] Read more.

Articulated tracked vehicles have been traditionally studied and appreciated for the extreme maneuverability and mobility flexibility in terms of grade and side slope capabilities. The articulation joint represents an attractive and advantageous solution, if compared to the traditional skid steering operation, by avoiding any trust adjustment between the outside and inside tracks. This paper focuses on the analysis and control of an articulated tracked vehicle characterized by two units connected through a mechanical multiaxial joint that is hydraulically actuated to allow the articulated steering operation. A realistic eight degrees of freedom mathematical model is introduced to include the main nonlinearities involved in the articulated steering behavior. A linearized vehicle model is further proposed to analytically characterize the cornering steady-state and transient behaviors for small lateral accelerations. Finally, a hitch angle controller is designed by proposing a torque-based and a speed-based Proportional Integral Derivative (PID) logics. The controller is also verified by simulating maneuvers typically adopted for handling analysis. Full article

(This article belongs to the Special Issue Italian Advances on MMS)

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12 pages, 1814 KiB

Open AccessEditor’s ChoiceCommunication

Chip Appearance Inspection Method for High-Precision SMT Equipment

by Huiyan Zhang, Hao Sun and Peng Shi

Machines 2021, 9(2), 34; https://doi.org/10.3390/machines9020034 - 07 Feb 2021

Cited by 6 | Viewed by 2862

Abstract

In order to meet the defect-detection requirements of chips in high-precision surface mount technology (SMT) equipment widely used in the electronic industry, a chip appearance defect-detection method based on multi-order fractional discrete wavelet packet decomposition (DWPD) is proposed in this paper. First, lead [...] Read more.

In order to meet the defect-detection requirements of chips in high-precision surface mount technology (SMT) equipment widely used in the electronic industry, a chip appearance defect-detection method based on multi-order fractional discrete wavelet packet decomposition (DWPD) is proposed in this paper. First, lead and body regions were extracted from chip images using the image segmentation algorithm with asymmetric Laplace mixture model and connected-component labelling algorithm; then, the texture feature of the region to be inspected was extracted with the multi-order fractional DWPD algorithm and the geometric and gradient features were combined to form image features of the region to be inspected before the subset of features was selected from image features with the feature selection algorithm based on the variational Bayesian Gaussian mixture model; and finally, the support vector machine was used to determine whether the region to be inspected was defective. An experiment was conducted on a data set captured in high-precision SMT equipment. The accuracy of the proposed chip appearance defect-detection method is about 93%, which is more accurate than existing ones. Full article

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38 pages, 14218 KiB

Open AccessEditor’s ChoiceArticle

Development and Research of Crosshead-Free Piston Hybrid Power Machine

by Viktor Shcherba, Viktor Shalay, Evgeniy Nosov, Evgeniy Pavlyuchenko and Ablai-Khan Tegzhanov

Machines 2021, 9(2), 32; https://doi.org/10.3390/machines9020032 - 05 Feb 2021

Cited by 6 | Viewed by 2389

Abstract

This article considers the development and research of a new design of crosshead-free piston hybrid power machine. After verification of a system of simplifying assumptions based on the fundamental laws of energy, mass, and motion conservation, as well as using the equation of [...] Read more.

This article considers the development and research of a new design of crosshead-free piston hybrid power machine. After verification of a system of simplifying assumptions based on the fundamental laws of energy, mass, and motion conservation, as well as using the equation of state, mathematical models of the work processes of the compressor section, pump section, and liquid flow in a groove seal have been developed. In accordance with the patent for the invention, a prototype of a crosshead-free piston hybrid power machine (PHPM) was developed; it was equipped with the necessary measuring equipment and a stand for studying the prototype. Using the developed mathematical model, the physical picture of the ongoing work processes in the compressor and pump sections is considered, taking into account their interaction through a groove seal. Using the developed plan, a set of experimental studies was carried out with the main operational parameters of the crosshead-free PHPM: operating processes, temperature of the cylinder–piston group and integral parameters (supply coefficient of the compressor section, volumetric efficiency of the pump section, etc.). As a result of numerical and experimental studies, it was determined that this PHPM design has better cooling of the compressor section (decrease in temperature of the valve plate is from 10 to 15 K; decrease in temperature of intake air is from 6 to 8 K, as well as there is increase in compressor and pump section efficiency up to 5%). Full article

(This article belongs to the Section Machines Testing and Maintenance)

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16 pages, 5085 KiB

Open AccessEditor’s ChoiceArticle

A Collision Avoidance Strategy for Redundant Manipulators in Dynamically Variable Environments: On-Line Perturbations of Off-Line Generated Trajectories

by Cecilia Scoccia, Giacomo Palmieri, Matteo Claudio Palpacelli and Massimo Callegari

Machines 2021, 9(2), 30; https://doi.org/10.3390/machines9020030 - 04 Feb 2021

Cited by 20 | Viewed by 3188

Abstract

In this work, a comprehensive control strategy for obstacle avoidance in redundant manipulation is presented, consisting of a combination of off-line path planning algorithms with on-line motion control. Path planning allows the avoidance of fixed obstacles detected before the start of the robot’s [...] Read more.

In this work, a comprehensive control strategy for obstacle avoidance in redundant manipulation is presented, consisting of a combination of off-line path planning algorithms with on-line motion control. Path planning allows the avoidance of fixed obstacles detected before the start of the robot’s motion; it is based on the potential fields method combined with a smoothing process realized by means of interpolation with Bezier curves. The on-line motion control is designed to compensate for the motion of the obstacles and to avoid collisions along the kinematic chain of the manipulator; it is realized by means of a velocity control law based on the null space method for redundancy control. A new term is introduced in the control law to take into account the speed of the obstacles as well as their position. Simulations on a simplified planar case are presented to assess the validity of the algorithms and to estimate the computational effort in order to verify the transferability of our approach to a real system. Full article

(This article belongs to the Special Issue Italian Advances on MMS)

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21 pages, 3323 KiB

Open AccessEditor’s ChoiceArticle

Machine Learning-Based Cognitive Position and Force Controls for Power-Assisted Human–Robot Collaborative Manipulation

by S. M. Mizanoor Rahman

Machines 2021, 9(2), 28; https://doi.org/10.3390/machines9020028 - 03 Feb 2021

Cited by 13 | Viewed by 3904

Abstract

Manipulation of heavy objects in industries is very necessary, but manual manipulation is tedious, adversely affects a worker’s health and safety, and reduces efficiency. On the contrary, autonomous robots are not flexible to manipulate heavy objects. Hence, we proposed human–robot systems, such as [...] Read more.

Manipulation of heavy objects in industries is very necessary, but manual manipulation is tedious, adversely affects a worker’s health and safety, and reduces efficiency. On the contrary, autonomous robots are not flexible to manipulate heavy objects. Hence, we proposed human–robot systems, such as power assist systems, to manipulate heavy objects in industries. Again, the selection of appropriate control methods as well as inclusion of human factors in the controls is important to make the systems human friendly. However, existing power assist systems do not address these issues properly. Hence, we present a 1-DoF (degree of freedom) testbed power assist robotic system for lifting different objects. We also included a human factor, such as weight perception (a cognitive cue), in the robotic system dynamics and derived several position and force control strategies/methods for the system based on the human-centric dynamics. We developed a reinforcement learning method to predict the control parameters producing the best/optimal control performance. We also derived a novel adaptive control algorithm based on human characteristics. We experimentally evaluated those control methods and compared the system performance between the control methods. Results showed that both position and force controls produced satisfactory performance, but the position control produced significantly better performance than the force controls. We then proposed using the results to design control methods for power assist robotic systems for handling large and heavy materials and objects in various industries, which may improve human–robot interactions (HRIs) and system performance. Full article

(This article belongs to the Special Issue Collaborative Robotics and Adaptive Machines)

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22 pages, 3240 KiB

Open AccessEditor’s ChoiceArticle

Operator-Based Nonlinear Control for a Miniature Flexible Actuator Using the Funnel Control Method

by Keisuke Ueno, Shuhei Kawamura and Mingcong Deng

Machines 2021, 9(2), 26; https://doi.org/10.3390/machines9020026 - 01 Feb 2021

Cited by 11 | Viewed by 2124

Abstract

Recently, the studies of soft actuators have been getting increased attention among various fields. Soft actuators are very safe for fragile objects and have an affinity to humans because they are composed of flexible materials. A miniature flexible actuator is a kind of [...] Read more.

Recently, the studies of soft actuators have been getting increased attention among various fields. Soft actuators are very safe for fragile objects and have an affinity to humans because they are composed of flexible materials. A miniature flexible actuator is a kind of pneumatically driven soft actuator. It has a bellowed shape and asymmetrical structure. This shape can generate a curling motion in two ways under positive and negative pressures with only one air tube. In the previous article, a control system using adaptive

λ

-tracking control was proposed. This control gain can become too large as time tends to infinity because the adaptive law exhibits a non-decreasing gain. To solve this problem, the funnel control method is proposed. The adaptive gain of this method not only increases but also decreases; however, the design scheme of the boundary function which is needed to decide on adaptive gain is not proposed here. In this article, an operator-based nonlinear control system’s design and the design scheme of the boundary function using an observer are proposed. Then, the effectiveness of the proposed method is verified by a simulation and an experiment. Full article

(This article belongs to the Section Automation and Control Systems)

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19 pages, 8849 KiB

Open AccessEditor’s ChoiceArticle

Evaluation of Grip Force and Energy Efficiency of the “Federica” Hand

by Daniele Esposito, Sergio Savino, Chiara Cosenza, Emilio Andreozzi, Gaetano Dario Gargiulo, Caitlin Polley, Giuseppe Cesarelli, Giovanni D’Addio and Paolo Bifulco

Machines 2021, 9(2), 25; https://doi.org/10.3390/machines9020025 - 27 Jan 2021

Cited by 16 | Viewed by 4241

Abstract

The actual grip force provided by a hand prosthesis is an important parameter to evaluate its efficiency. To this end, a split cylindrical handlebar embedding a single-axis load cell was designed, 3D printed and assembled. Various measurements were made to evaluate the performances [...] Read more.

The actual grip force provided by a hand prosthesis is an important parameter to evaluate its efficiency. To this end, a split cylindrical handlebar embedding a single-axis load cell was designed, 3D printed and assembled. Various measurements were made to evaluate the performances of the “Federica” hand, a simple low-cost hand prosthesis. The handlebar was placed at different angular positions with respect to the hand palm, and the experimental data were processed to estimate the overall grip force. In addition, piezoresistive force sensors were applied on selected phalanxes of the prosthesis, in order to map the distribution of the grasping forces between them. The electrical current supplied to the single servomotor that actuates all the five fingers, was monitored to estimate the force exerted on the main actuator tendon, while tendon displacement was evaluated by a rotary potentiometer fixed to the servomotor shaft. The force transfer ratio of the whole system was about 12.85 %, and the mean dissipated energy for a complete cycle of closing-opening was 106.80 Nmm, resulting lower than that of many commercial prostheses. The mean grip force of the “Federica” hand was 8.80 N, that is enough to support the user in many actions of daily life, also considering the adaptive wrapping capability of the prosthesis. On average, the middle phalanges exerted the greatest grip force (2.65 N) on the handlebar, while the distal phalanges a force of 1.66 N. Full article

(This article belongs to the Section Robotics, Mechatronics and Intelligent Machines)

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23 pages, 6925 KiB

Open AccessEditor’s ChoiceArticle

Precise Locating Control for a Polar Crane Based on Sliding Mode Active Disturbance Rejection Control and Quadratic Programming Algorithm

by Xuyang Cao, Zhiwei Wang and Xingang Zhang

Machines 2021, 9(2), 22; https://doi.org/10.3390/machines9020022 - 20 Jan 2021

Cited by 6 | Viewed by 2621

Abstract

A polar crane is a large-scale special lifting equipment operated in a nuclear power plant. To address the precise locating control problem of a polar crane with the center of gravity shifting, with cross-coupling, and with external disturbance, an effective control scheme is [...] Read more.

A polar crane is a large-scale special lifting equipment operated in a nuclear power plant. To address the precise locating control problem of a polar crane with the center of gravity shifting, with cross-coupling, and with external disturbance, an effective control scheme is proposed in this paper. Firstly, a nonholonomic constraint dynamic model of the polar crane is established according to the Lagrange–Rouse equation. Then, an expansion state observer (ESO) of the active disturbance rejection control (ADRC) method is applied to estimate and compensate the cross-coupling disturbance in real-time. To improve the robustness and convergence speed of the control system, the nonsingular terminal sliding mode (NTSM) control method is incorporated with ADRC and the stability of the controller is proven by the Lyapunov function approach. Furthermore, to solve the problem of redundant actuation and to reduce trajectory deviation of the bridge truck, the contact forces of the horizontal guide device are introduced into the quadratic programming (QP) optimization algorithm. Finally, the effectiveness and superiority of the proposed control scheme are illustrated by simulation results. Full article

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10 pages, 2965 KiB

Open AccessEditor’s ChoiceCommunication

Optimal Design of Double-Pole Magnetization BLDC Motor and Comparison with Single-Pole Magnetization BLDC Motor in Terms of Electromagnetic Performance

by Hyo-Seob Shin, Gang-Hyeon Jang, Kyung-Hun Jung, Seong-Kook Cho, Jang-Young Choi and Hyeon-Jae Shin

Machines 2021, 9(1), 18; https://doi.org/10.3390/machines9010018 - 17 Jan 2021

Cited by 1 | Viewed by 6194

Abstract

This study presents an optimal double-pole magnetization brushless DC (BLDC) motor design, compared to a single-pole magnetization BLDC motor in terms of electromagnetic performance. Initially, a double-pole model is selected based on the permanent magnet (PM) of the single-pole model. The pole separation [...] Read more.

This study presents an optimal double-pole magnetization brushless DC (BLDC) motor design, compared to a single-pole magnetization BLDC motor in terms of electromagnetic performance. Initially, a double-pole model is selected based on the permanent magnet (PM) of the single-pole model. The pole separation space, which is generated in the magnetization process of the double-pole PM, is selected based on the pole space of the single-pole model. Moreover, the PM offset is selected considering the PM volume of the single-pole model. Further, an optimal model is selected using the multiple response optimal method, which is a type of response surface methodology (RSM). The objective of the optimal design is to maintain the back EMF and decrease the cogging torque; the design variables include the pole separation space and PM offset. The experimental points of the initial model are designed using the central composite method (CCD). Finally, the optimization is verified by comparing the experimental and analysis results of the single-pole model with the analysis results of the optimal model. Full article

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22 pages, 13297 KiB

Open AccessEditor’s ChoiceArticle

Experimental Investigation of the Leaf Type Bearing Structure with Undersprings Under Dynamic Excitation

by Hannes Schmiedeke, Michael Sinapius and Nontavut Prechavut

Machines 2021, 9(1), 15; https://doi.org/10.3390/machines9010015 - 15 Jan 2021

Cited by 1 | Viewed by 2538

Abstract

With foil bearings, rotors achieve high rotational speeds with less friction and wear. In addition, here the required space is small and no peripheral components like liquid tanks or pumps are needed. The drawback is a more complex prediction of the real behavior [...] Read more.

With foil bearings, rotors achieve high rotational speeds with less friction and wear. In addition, here the required space is small and no peripheral components like liquid tanks or pumps are needed. The drawback is a more complex prediction of the real behavior in rotordynamic systems. Impedance test rigs are suitable for investigating the structural-dynamic bearing properties and for validating the theoretical models. This article presents and discusses the measurement of dynamic behavior, i.e., stiffness and damping coefficients, of the structure of a leaf type bearing with undersprings. These measurements include variations in static load due to the relative displacement of the bearing and shaft as well as an attempt to explain the noticed anisotropic behavior of the bearing. This article also shows how much a controlled excitation improves the comparability across the frequency band. For this purpose, a test rig is presented that has been further developed in comparison to known literature approaches. The results show, that the loss factors of the examined bearing structure are up to 4 times bigger below lift-off compared to the operation at 60,000 rpm. Furthermore, the movement amplitudes and the static loads have a great influence on the stiffness and the damping. Full article

(This article belongs to the Section Automation and Control Systems)

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33 pages, 1293 KiB

Open AccessEditor’s ChoiceReview

Data-Driven Intelligent 3D Surface Measurement in Smart Manufacturing: Review and Outlook

by Yuhang Yang, Zhiqiao Dong, Yuquan Meng and Chenhui Shao

Machines 2021, 9(1), 13; https://doi.org/10.3390/machines9010013 - 13 Jan 2021

Cited by 17 | Viewed by 4001

Abstract

High-fidelity characterization and effective monitoring of spatial and spatiotemporal processes are crucial for high-performance quality control of many manufacturing processes and systems in the era of smart manufacturing. Although the recent development in measurement technologies has made it possible to acquire high-resolution three-dimensional [...] Read more.

High-fidelity characterization and effective monitoring of spatial and spatiotemporal processes are crucial for high-performance quality control of many manufacturing processes and systems in the era of smart manufacturing. Although the recent development in measurement technologies has made it possible to acquire high-resolution three-dimensional (3D) surface measurement data, it is generally expensive and time-consuming to use such technologies in real-world production settings. Data-driven approaches that stem from statistics and machine learning can potentially enable intelligent, cost-effective surface measurement and thus allow manufacturers to use high-resolution surface data for better decision-making without introducing substantial production cost induced by data acquisition. Among these methods, spatial and spatiotemporal interpolation techniques can draw inferences about unmeasured locations on a surface using the measurement of other locations, thus decreasing the measurement cost and time. However, interpolation methods are very sensitive to the availability of measurement data, and their performances largely depend on the measurement scheme or the sampling design, i.e., how to allocate measurement efforts. As such, sampling design is considered to be another important field that enables intelligent surface measurement. This paper reviews and summarizes the state-of-the-art research in interpolation and sampling design for surface measurement in varied manufacturing applications. Research gaps and future research directions are also identified and can serve as a fundamental guideline to industrial practitioners and researchers for future studies in these areas. Full article

(This article belongs to the Section Advanced Manufacturing)

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17 pages, 10547 KiB

Open AccessEditor’s ChoiceArticle

Definition of Damage Indices for Railway Axle Bearings: Results of Long-Lasting Tests

by Paolo Pennacchi, Steven Chatterton, Andrea Vania and Davide Massocchi

Machines 2021, 9(1), 12; https://doi.org/10.3390/machines9010012 - 13 Jan 2021

Cited by 5 | Viewed by 3302

Abstract

The European Rail Transport System has set goals of improving the reliability, availability, durability, high-speed capacity, and maintenance. In this context, the condition monitoring approach is of fundamental importance for all components of the “train” system. The authors have long been in the [...] Read more.

The European Rail Transport System has set goals of improving the reliability, availability, durability, high-speed capacity, and maintenance. In this context, the condition monitoring approach is of fundamental importance for all components of the “train” system. The authors have long been in the diagnostics of the railway traction system, with a focus on rolling element bearings. In this paper, signal processing techniques, already developed in the past and experimentally validated in the railway field, are applied to vibration data for the definition of damage indices for railway axle bearings. This allows to evaluate the “status” of the bearing and the monitoring of the evolution of any damage that may occur. The experimental data were obtained by means of a test-rig built according to EN 12082:2017 and following the test specifications of the same standard. Full article

(This article belongs to the Special Issue Italian Advances on MMS)

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10 pages, 7509 KiB

Open AccessEditor’s ChoiceLetter

Surface Texture after Turning for Various Workpiece Rigidities

by Michal Dobrzynski and Karolina Mietka

Machines 2021, 9(1), 9; https://doi.org/10.3390/machines9010009 - 12 Jan 2021

Cited by 10 | Viewed by 2011

Abstract

In the paper, we present an analysis of the surface texture of turned parts with L/D (length/diameter) ratios of 6 and 12 and various rigidity values. The studies were carried out on samples made of S355JR steel and AISI 304 stainless steel. A [...] Read more.

In the paper, we present an analysis of the surface texture of turned parts with L/D (length/diameter) ratios of 6 and 12 and various rigidity values. The studies were carried out on samples made of S355JR steel and AISI 304 stainless steel. A detailed analysis of 2D surface profiles was carried out by using a large number of parameters that allowed us to distinguish significant differences in the surface microgeometry, which confirmed that determining surface characteristics from one height parameter (Ra—arithmetical mean height) is far from sufficient. The obtained results indicate significantly better roughness and waviness values of the AISI 304 steel surfaces in terms of its size, periodicity, and regularity. Therefore, the turning process of AISI 304 shafts with low rigidity allows one to be able to achieve better quality texture and have a positive effect on the general properties of a workpiece. In all tested samples, surface irregularities decreased along with the distance from the tailstock. The shafts with an L/D ratio of 12 had worse surfaces in the first two sections due to lower rigidity. The results received close to the three-jaw chuck, regardless of the L/D ratio and material type, demonstrated similar waviness and roughness parameters and profiles. Full article

(This article belongs to the Special Issue Advances and Trends in Non-conventional, Abrasive and Precision Machining)

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11 pages, 3557 KiB

Open AccessEditor’s ChoiceArticle

Functional Design of a Hybrid Leg-Wheel-Track Ground Mobile Robot

by Luca Bruzzone, Mario Baggetta, Shahab E. Nodehi, Pietro Bilancia and Pietro Fanghella

Machines 2021, 9(1), 10; https://doi.org/10.3390/machines9010010 - 12 Jan 2021

Cited by 40 | Viewed by 7592

Abstract

This paper presents the conceptual and functional design of a novel hybrid leg-wheel-track ground mobile robot for surveillance and inspection, named WheTLHLoc (Wheel-Track-Leg Hybrid Locomotion). The aim of the work is the development of a general-purpose platform capable of combining tracked locomotion on [...] Read more.

This paper presents the conceptual and functional design of a novel hybrid leg-wheel-track ground mobile robot for surveillance and inspection, named WheTLHLoc (Wheel-Track-Leg Hybrid Locomotion). The aim of the work is the development of a general-purpose platform capable of combining tracked locomotion on irregular and yielding terrains, wheeled locomotion with high energy efficiency on flat and compact grounds, and stair climbing/descent ability. The architecture of the hybrid locomotion system is firstly outlined, then the validation of its stair climbing maneuver capabilities by means of multibody simulation is presented. The embodiment design and the internal mechanical layout are then discussed. Full article

(This article belongs to the Special Issue Latest Trends of Autonomous Aerial and Terrestrial Vehicles for Service Robotics Applications)

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16 pages, 6379 KiB

Open AccessEditor’s ChoiceArticle

Working Speed Analysis of the Gear-Driven Dibbling Mechanism of a 2.6 kW Walking-Type Automatic Pepper Transplanter

by Md Zafar Iqbal, Md Nafiul Islam, Milon Chowdhury, Sumaiya Islam, Tusan Park, Yong-Joo Kim and Sun-Ok Chung

Machines 2021, 9(1), 6; https://doi.org/10.3390/machines9010006 - 11 Jan 2021

Cited by 16 | Viewed by 4155

Abstract

The development of an automatic walking-type pepper transplanter could be effective in improving the mechanization rate in pepper cultivation, where the dibbling mechanism plays a vital role and determines planting performance and efficiency. The objective of this research was to determine a suitable [...] Read more.

The development of an automatic walking-type pepper transplanter could be effective in improving the mechanization rate in pepper cultivation, where the dibbling mechanism plays a vital role and determines planting performance and efficiency. The objective of this research was to determine a suitable working speed for a gear-driven dibbling mechanism appropriate for a pepper transplanter, while considering agronomic transplanting requirements. The proposed dibbling mechanism consisted of two dibbling hoppers that simultaneously collected free-falling seedlings from the supply mechanism and dibbled them into soil. To enable the smooth collection and plantation of pepper seedlings, analysis was carried out via a mathematical working trajectory model of the dibbling mechanism, virtual prototype simulation, and validation tests, using a physical prototype. In the mathematical model analysis and simulation, a 300 mm/s forward speed of the transplanter and a 60 rpm rotational speed of the dibbling mechanism were preferable in terms of seedling uprightness and low mulch film damage. During the field test, transplanting was conducted at a 40 mm planting depth, using different forward speed levels. Seedlings were freely supplied to the hopper from a distance of 80 mm, and the success rate for deposition was 96.79%. A forward speed of 300 mm/s with transplanting speed of 120 seedlings/min was preferable in terms of achieving a high degree of seedling uprightness (90 ± 3.26), a low rate of misplanting (8.19%), a low damage area on mulch film (2341.95 ± 2.89 mm²), high uniformity of planting depth (39.74 ± 0.48 mm), and low power consumption (40.91 ± 0.97 W). Full article

(This article belongs to the Section Machines Testing and Maintenance)

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15 pages, 37237 KiB

Open AccessEditor’s ChoiceArticle

Surface Finishing of Zirconium Dioxide with Abrasive Brushing Tools

by Eckart Uhlmann and Anton Hoyer

Machines 2020, 8(4), 89; https://doi.org/10.3390/machines8040089 - 21 Dec 2020

Cited by 9 | Viewed by 2402

Abstract

Brushing with bonded abrasives is a finishing process which can be used for the surface improvement of various materials. Since the machining mechanisms of abrasive brushing processes are still largely unknown and little predating research was done on brushing ceramic workpieces, within the [...] Read more.

Brushing with bonded abrasives is a finishing process which can be used for the surface improvement of various materials. Since the machining mechanisms of abrasive brushing processes are still largely unknown and little predating research was done on brushing ceramic workpieces, within the scope of this work technological investigations were carried out on planar workpieces of MgO-PSZ (zirconium dioxide, ZrO₂) using brushing tools with bonded grains of polycrystalline diamond. The primary goal was the reduction of grinding-related surface defects under the preservation of surface roughness valleys and workpiece form. Based on microscopy and topography measurements, the grain size s_g and the brushing velocity v_b were found to have a considerable influence on the processing result. Furthermore, excessive tool wear was observed while brushing ceramics. Full article

(This article belongs to the Special Issue Advances and Trends in Non-conventional, Abrasive and Precision Machining)

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15 pages, 4044 KiB

Open AccessEditor’s ChoiceArticle

A Smart Stent for Monitoring Eventual Restenosis: Computational Fluid Dynamic and Finite Element Analysis in Descending Thoracic Aorta

by Betsy D. M. Chaparro-Rico, Fabio Sebastiano and Daniele Cafolla

Machines 2020, 8(4), 81; https://doi.org/10.3390/machines8040081 - 24 Nov 2020

Cited by 7 | Viewed by 3664

Abstract

Even though scientific studies of smart stents are extensive, current smart stents focus on pressure sensors. This paper presents a novel implantable biocompatible smart stent for monitoring eventual restenosis. The device is comprised of a metal mesh structure, a biocompatible and adaptable envelope, [...] Read more.

Even though scientific studies of smart stents are extensive, current smart stents focus on pressure sensors. This paper presents a novel implantable biocompatible smart stent for monitoring eventual restenosis. The device is comprised of a metal mesh structure, a biocompatible and adaptable envelope, and pair-operated ultrasonic sensors for restenosis monitoring through flow velocity. Aside from continuous monitoring of restenosis post-implantation, it is also important to evaluate whether the stent design itself causes complications such as restenosis or thrombosis. Therefore, computational fluid dynamic (CFD) analysis before and after stent implantation were carried out as well as finite element analysis (FEA). The proposed smart stent was put in the descending thoracic section of a virtually reconstructed aorta that comes from a computed tomography (CT) scan. Blood flow velocity showed that after stent implantation, there is not liquid retention or vortex generation. In addition, blood pressures after stent implantation were within the normal blood pressure values. The stress and the factor of safety (FOS) analysis showed that the stress values reached by the stent are very far from the yield strength limit of the materials and that the stent is stiff enough to support the applied loads exported from the CFD results. Full article

(This article belongs to the Special Issue Italian Advances on MMS)

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15 pages, 8335 KiB

Open AccessEditor’s ChoiceArticle

Gallium Nitride Inverter Design with Compatible Snubber Circuits for Implementing Wireless Charging of Electric Vehicle Batteries

by Fatemeh Rahmani, Payam Niknejad, Tanushree Agarwal and Mohammadreza Barzegaran

Machines 2020, 8(3), 56; https://doi.org/10.3390/machines8030056 - 15 Sep 2020

Cited by 10 | Viewed by 3661

Abstract

High-frequency wireless power transfer (WPT) technology provides superior compatibility in the alignment with various WPT standards. However, high-efficiency and compact single-phase power switching systems with ideal snubber circuits are required for maximum power transfer capability. This research aims to develop an inverter using [...] Read more.

High-frequency wireless power transfer (WPT) technology provides superior compatibility in the alignment with various WPT standards. However, high-efficiency and compact single-phase power switching systems with ideal snubber circuits are required for maximum power transfer capability. This research aims to develop an inverter using Gallium Nitride (GaN) power transistors, optimized RCD (resistor/capacitor/diode) snubber circuits, and gate drivers, each benefitting WPT technology by reducing the switching and conduction loss in charging electric vehicle batteries. A full-bridge GaN inverter was simulated and instituted as part of the wireless charging circuit design. The RCD circuits were adjusted by transferring maximum power from the power supply to the transmitter inductor. For verification of the simulated output, lab-scale experiments were implemented for two half-bridges controlled by gate drivers with corresponding snubber circuits. After authenticating the output results, the GaN inverter was tested with an input range of 30 V to deduce the success of charging electric vehicle batteries within an efficient time frame. The developed inverter, at 80 kHz frequency, was applied in place of a ready-to-use evaluation board, fully reducing less harmonic distortion and greatly increasing WPT system efficiency (~93%). In turn, the designed GaN inverter boasts considerable energy savings, resulting in a more cost-effective solution for manufacturers. Full article

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18 pages, 13110 KiB

Open AccessEditor’s ChoiceArticle

Studying the Effect of Working Conditions on WEDM Machining Performance of Super Alloy Inconel 617

by Stefan Dzionk and Mieczysław S. Siemiątkowski

Machines 2020, 8(3), 54; https://doi.org/10.3390/machines8030054 - 09 Sep 2020

Cited by 20 | Viewed by 3179

Abstract

Wire electrical discharge machining (WEDM) has been, for many years, a precise and efficient non-conventional manufacturing solution in various industrial applications, mostly involving the use of hard-to-machine materials like, among others, the Inconel super alloys. The focus of the present study is on [...] Read more.

Wire electrical discharge machining (WEDM) has been, for many years, a precise and efficient non-conventional manufacturing solution in various industrial applications, mostly involving the use of hard-to-machine materials like, among others, the Inconel super alloys. The focus of the present study is on exploring the effect of selected control parameters, including pulse duration, pulse-off time and the dielectric flow pressure on the WEDM process performance characteristics of Inconel 617 material, such as: volumetric material removal rate (MRR), the dimensional accuracy of cutting (reflected by the kerf width) and surface roughness (SR). The research experiment has been designed and carried out using the response surface methodology (RSM) accordingly with the Box–Behnken design scheme. The results of experiments derived in the form of a fitted regression model have been subjected to the analysis of variance (ANOVA) tests. Thus, the variable process parameters and the relevant interactions between them, characterized by a significant influence on the values of the derived output responses, could be explicitly determined. Full article

(This article belongs to the Special Issue Advances and Trends in Non-conventional, Abrasive and Precision Machining)

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20 pages, 5518 KiB

Open AccessEditor’s ChoiceArticle

Advanced Strategy of Speed Predictive Control for Nonlinear Synchronous Reluctance Motors

by Ahmed Farhan, Mohamed Abdelrahem, Christoph M. Hackl, Ralph Kennel, Adel Shaltout and Amr Saleh

Machines 2020, 8(3), 44; https://doi.org/10.3390/machines8030044 - 01 Aug 2020

Cited by 17 | Viewed by 3251

Abstract

To gain fast dynamic response, high performance, and good tracking capability, several control strategies have been applied to synchronous reluctance motors (SynRMs). In this paper, a nonlinear advanced strategy of speed predictive control (SPC) based on the finite control set model predictive control [...] Read more.

To gain fast dynamic response, high performance, and good tracking capability, several control strategies have been applied to synchronous reluctance motors (SynRMs). In this paper, a nonlinear advanced strategy of speed predictive control (SPC) based on the finite control set model predictive control (FCS-MPC) is proposed and simulated for nonlinear SynRMs. The SPC overcomes the limitation of the cascaded control structure of the common vector control by employing a novel strategy that considers all the electrical and mechanical variables in one control law through a new cost function to obtain the switching signals for the power converter. The SynRM flux maps are known based on finite element method (FEM) analysis to take into consideration the effect of the nonlinearity of the machine. To clear the proposed strategy features, a functional and qualitative comparison between the proposed SPC, field-oriented control (FOC) with an anti-windup scheme, and current predictive control (CPC) with outer PI speed control loop is presented. For simplicity, particle swarm optimization (PSO) is performed to tune all the unknown parameters of the control strategies. The comparison features include controller design, dynamic and steady-state behaviors. Simulation results are presented to investigate the benefits and limitations of the three control strategies. Finally, the proposed SPC, FOC, and CPC have their own merits, and all methods encounter the requirements of advanced high-performance drives. Full article

(This article belongs to the Special Issue Design and Control of Rotating Electrical Machines)

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16 pages, 4644 KiB

Open AccessEditor’s ChoiceReview

An Overview of Electric Machine Trends in Modern Electric Vehicles

by Emmanuel Agamloh, Annette von Jouanne and Alexandre Yokochi

Machines 2020, 8(2), 20; https://doi.org/10.3390/machines8020020 - 17 Apr 2020

Cited by 92 | Viewed by 29131

Abstract

Electric machines are critical components of the drivetrains of electric vehicles. Over the past few years the majority of traction drive systems have converged toward containing some form of a permanent magnet machine. There is increasing tendency toward the improvement of power density [...] Read more.

Electric machines are critical components of the drivetrains of electric vehicles. Over the past few years the majority of traction drive systems have converged toward containing some form of a permanent magnet machine. There is increasing tendency toward the improvement of power density and efficiency of traction machines, thereby giving rise to innovative designs and improvements of basic machine topologies and the emergence of new classes of machines. This paper provides an overview of present trends toward high specific power density machines for traction drive systems. The focus will be on current technology and the trends that are likely to be pursued in the near future to achieve the high specific power goals set for the industry. The paper discusses machines that are applied in both hybrid and battery electric drivetrains without distinction and does not discuss the associated power electronic inverters. Future electric machine trends that are likely to occur are also projected. Full article

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22 pages, 2573 KiB

Open AccessEditor’s ChoiceArticle

Electric Machine Design Tool for Permanent Magnet Synchronous Machines and Induction Machines

by Svenja Kalt, Jonathan Erhard and Markus Lienkamp

Machines 2020, 8(1), 15; https://doi.org/10.3390/machines8010015 - 24 Mar 2020

Cited by 19 | Viewed by 9136

Abstract

The rising mobility demand of today’s society leads to an increasing strain of noise and pollutant emissions on people and the environment. An increasing environmental awareness and the scarcity of fossil fuels are increasingly placing alternative-powered vehicles in the focus of politics, research [...] Read more.

The rising mobility demand of today’s society leads to an increasing strain of noise and pollutant emissions on people and the environment. An increasing environmental awareness and the scarcity of fossil fuels are increasingly placing alternative-powered vehicles in the focus of politics, research and development. Electric vehicles represent a promising solution to this problem. The electric machine represents a design control lever for the optimization of the electric powertrain with regard to efficiency, power, weight and size. Therefore, accurate and realistic machine design tools for the design of electric machines are becoming increasingly important. In this paper, the authors present an electric machine design tool for electric machines using MATLAB^® in order to enable an automated machine design. The electric machine design tool is published under an LGPL open source license. Full article

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18 pages, 5063 KiB

Open AccessEditor’s ChoiceArticle

Electromagnetic Analysis and Design Methodology for Permanent Magnet Motors Using MotorAnalysis-PM Software

by Vladimir Kuptsov, Poria Fajri, Andrzej Trzynadlowski, Guoliang Zhang and Salvador Magdaleno-Adame

Machines 2019, 7(4), 75; https://doi.org/10.3390/machines7040075 - 06 Dec 2019

Cited by 16 | Viewed by 10577

Abstract

This article presents a new and powerful freeware software called MotorAnalysis-PM and discusses its application in electromagnetic design and analysis of permanent magnet (PM) motors for the electric vehicle (EV) industry. This new PM motor software utilizes both finite element (FE) and analytical [...] Read more.

This article presents a new and powerful freeware software called MotorAnalysis-PM and discusses its application in electromagnetic design and analysis of permanent magnet (PM) motors for the electric vehicle (EV) industry. This new PM motor software utilizes both finite element (FE) and analytical methods to speed up the analysis and design process of PM motors significantly. The analysis and design methodology using MotorAnalysis-PM is presented and discussed for a 50 kW PM motor utilized in a commercial EV. To validate the accuracy of the software, the numerical results obtained from the PM motor design and analysis tool are compared with experimental results. The numerical and experimental results validate the flexibility of this software in achieving accurate motor design with short design times which is of great interest to EV and PM motor manufacturers. Full article

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19 pages, 3899 KiB

Open AccessEditor’s ChoiceArticle

Experimental Vibration Analysis of a Small Scale Vertical Wind Energy System for Residential Use

by Francesco Castellani, Davide Astolfi, Mauro Peppoloni, Francesco Natili, Daniele Buttà and Alexander Hirschl

Machines 2019, 7(2), 35; https://doi.org/10.3390/machines7020035 - 22 May 2019

Cited by 26 | Viewed by 9421

Abstract

In the recent years, distributed energy production has been one of the main research topics about renewable energies. The decentralization of electric production from wind resources raises the issues of reducing the size of generators, from the MW scale of industrial wind farm [...] Read more.

In the recent years, distributed energy production has been one of the main research topics about renewable energies. The decentralization of electric production from wind resources raises the issues of reducing the size of generators, from the MW scale of industrial wind farm turbines to the kW scale, and possibly employing them in urban areas, where the wind flow is complex and extremely turbulent because of the presence of buildings and obstacles. On these grounds, the use of small-scale vertical axis small wind turbines (VASWT) is a valid choice for on-site generation (OSG), considering their low sensitivity with respect to turbulent flow and that there is no need to align the turbine with wind direction, as occurs with horizontal axis small wind turbines (HASWT). In addition, VASWTs have a minor acoustic impact with respect to HASWTs. The aim of this paper is to study the interactions that take place between a 1.2 kW, vertical axis, Darrieus VASWT turbine and a small, experimental building, in order to analyze the noise and the vibrations transmitted to the structure. One method to damp the vibrations is then assessed through spectral analysis of data acquired through accelerometers located both in the mast of the wind turbine and at the building walls. The results confirm the usefulness of dampers to increase the building comfort regarding vibrations. Full article

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14 pages, 3752 KiB

Open AccessEditor’s ChoiceArticle

Deep Learning-Based Landmark Detection for Mobile Robot Outdoor Localization

by Sivapong Nilwong, Delowar Hossain, Shin-ichiro Kaneko and Genci Capi

Machines 2019, 7(2), 25; https://doi.org/10.3390/machines7020025 - 18 Apr 2019

Cited by 40 | Viewed by 6560

Abstract

Outdoor mobile robot applications generally implement Global Positioning Systems (GPS) for localization tasks. However, GPS accuracy in outdoor localization has less accuracy in different environmental conditions. This paper presents two outdoor localization methods based on deep learning and landmark detection. The first localization [...] Read more.

Outdoor mobile robot applications generally implement Global Positioning Systems (GPS) for localization tasks. However, GPS accuracy in outdoor localization has less accuracy in different environmental conditions. This paper presents two outdoor localization methods based on deep learning and landmark detection. The first localization method is based on the Faster Regional-Convolutional Neural Network (Faster R-CNN) landmark detection in the captured image. Then, a feedforward neural network (FFNN) is trained to determine robot location coordinates and compass orientation from detected landmarks. The second localization employs a single convolutional neural network (CNN) to determine location and compass orientation from the whole image. The dataset consists of images, geolocation data and labeled bounding boxes to train and test two proposed localization methods. Results are illustrated with absolute errors from the comparisons between localization results and reference geolocation data in the dataset. The experimental results pointed both presented localization methods to be promising alternatives to GPS for outdoor localization. Full article

(This article belongs to the Special Issue Selected Papers from Conference on Control, Mechatronics and Automation (ICCMA))

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14 pages, 522 KiB

Open AccessEditor’s ChoiceArticle

Neural Network-Based Learning from Demonstration of an Autonomous Ground Robot

by Yiwei Fu, Devesh K. Jha, Zeyu Zhang, Zhenyuan Yuan and Asok Ray

Machines 2019, 7(2), 24; https://doi.org/10.3390/machines7020024 - 15 Apr 2019

Cited by 14 | Viewed by 4621

Abstract

This paper presents and experimentally validates a concept of end-to-end imitation learning for autonomous systems by using a composite architecture of convolutional neural network (ConvNet) and Long Short Term Memory (LSTM) neural network. In particular, a spatio-temporal deep neural network is developed, which [...] Read more.

This paper presents and experimentally validates a concept of end-to-end imitation learning for autonomous systems by using a composite architecture of convolutional neural network (ConvNet) and Long Short Term Memory (LSTM) neural network. In particular, a spatio-temporal deep neural network is developed, which learns to imitate the policy used by a human supervisor to drive a car-like robot in a maze environment. The spatial and temporal components of the imitation model are learned by using deep convolutional network and recurrent neural network architectures, respectively. The imitation model learns the policy of a human supervisor as a function of laser light detection and ranging (LIDAR) data, which is then used in real time to drive a robot in an autonomous fashion in a laboratory setting. The performance of the proposed model for imitation learning is compared with that of several other state-of-the-art methods, reported in the machine learning literature, for spatial and temporal modeling. The learned policy is implemented on a robot using a Nvidia Jetson TX2 board which, in turn, is validated on test tracks. The proposed spatio-temporal model outperforms several other off-the-shelf machine learning techniques to learn the policy. Full article

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18 pages, 3300 KiB

Open AccessEditor’s ChoiceArticle

Tailor-Made Hand Exoskeletons at the University of Florence: From Kinematics to Mechatronic Design

by Nicola Secciani, Matteo Bianchi, Alessandro Ridolfi, Federica Vannetti, Yary Volpe, Lapo Governi, Massimo Bianchini and Benedetto Allotta

Machines 2019, 7(2), 22; https://doi.org/10.3390/machines7020022 - 03 Apr 2019

Cited by 19 | Viewed by 6235

Abstract

Recently, robotics has increasingly become a companion for the human being and assisting physically impaired people with robotic devices is showing encouraging signs regarding the application of this largely investigated technology to the clinical field. As of today, however, exoskeleton design can still [...] Read more.

Recently, robotics has increasingly become a companion for the human being and assisting physically impaired people with robotic devices is showing encouraging signs regarding the application of this largely investigated technology to the clinical field. As of today, however, exoskeleton design can still be considered a hurdle task and, even in modern robotics, aiding those patients who have lost or injured their limbs is surely one of the most challenging goal. In this framework, the research activity carried out by the Department of Industrial Engineering of the University of Florence concentrated on the development of portable, wearable and highly customizable hand exoskeletons to aid patients suffering from hand disabilities, and on the definition of patient-centered design strategies to tailor-made devices specifically developed on the different users’ needs. Three hand exoskeletons versions will be presented in this paper proving the major taken steps in mechanical designing and controlling a compact and lightweight solution. The performance of the resulting systems has been tested in a real-use scenario. The obtained results have been satisfying, indicating that the derived solutions may constitute a valid alternative to existing hand exoskeletons so far studied in the rehabilitation and assistance fields. Full article

(This article belongs to the Special Issue Advances of Italian Machine Design)

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13 pages, 4208 KiB

Open AccessEditor’s ChoiceArticle

Application of IoT-Aided Simulation to Manufacturing Systems in Cyber-Physical System

by Yifei Tan, Wenhe Yang, Kohtaroh Yoshida and Soemon Takakuwa

Machines 2019, 7(1), 2; https://doi.org/10.3390/machines7010002 - 03 Jan 2019

Cited by 50 | Viewed by 7556

Abstract

With the rapid development of mobile and wireless networking technologies, data has become more ubiquitous and the IoT (Internet of Things) is attracting much attention due to high expectations for enabling innovative service, efficiency, and productivity improvement. In next-generation manufacturing, the digital twin [...] Read more.

With the rapid development of mobile and wireless networking technologies, data has become more ubiquitous and the IoT (Internet of Things) is attracting much attention due to high expectations for enabling innovative service, efficiency, and productivity improvement. In next-generation manufacturing, the digital twin (DT) has been proposed as a new concept and simulation tool for collecting and synchronizing real-world information in real time in cyber space to cope with the challenges of smart factories. Although the DT is considered a challenging technology, it is still at the conceptual stage and only a few studies have specifically discussed methods for its construction and implementation. In this study, we first explain the concept of DT and important issues involved in developing it within an IoT-aided manufacturing environment. Then, we propose a DT construction framework and scheme for inputting data derived from the IoT into a simulation model. Finally, we describe how we verify the effectiveness of the proposed framework and scheme, by constructing a DT-oriented simulation model for an IoT-aided manufacturing system. Full article

(This article belongs to the Special Issue Smart Manufacturing)

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16 pages, 4281 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Integrated Fault Detection Framework for Classifying Rotating Machine Faults Using Frequency Domain Data Fusion and Artificial Neural Networks

by Kenisuomo C. Luwei, Akilu Yunusa-Kaltungo and Yusuf A. Sha’aban

Machines 2018, 6(4), 59; https://doi.org/10.3390/machines6040059 - 20 Nov 2018

Cited by 45 | Viewed by 5205

Abstract

The availability of complex rotating machines is vital for the prevention of catastrophic failures in a significant number of industrial operations. Reliability engineering theories stipulate that optimising the mean-time-to-repair (MTTR) for failed machines can immensely boost availability. In practice, however, a significant amount [...] Read more.

The availability of complex rotating machines is vital for the prevention of catastrophic failures in a significant number of industrial operations. Reliability engineering theories stipulate that optimising the mean-time-to-repair (MTTR) for failed machines can immensely boost availability. In practice, however, a significant amount of time is taken to accurately detect and classify rotor-related anomalies which often negate the drive to achieve a truly robust maintenance decision-making system. Earlier studies have attempted to address these limitations by classifying the poly coherent composite spectra (pCCS) features generated at different machine speeds using principal components analysis (PCA). As valuable as the observations obtained were, the PCA-based classifications applied are linear which may or may not limit their applicability to some real-life machine vibration data that are often associated with certain degrees of non-linearities due to faults. Additionally, the PCA-based faults classification approach used in earlier studies sometimes lack the capability to self-learn which implies that routine machine health classifications would be done manually. The initial parts of the current paper were presented in the form of a thorough search of the literature related to the general concept of data fusion approaches in condition monitoring (CM) of rotation machines. Based on the potentials of pCCS features, the later parts of the article are concerned with the application of the same features for the exploration of a simplified two-staged artificial neural network (ANN) classification approach that could pave the way for the automatic classification of rotating machines faults. This preliminary examination of the classification accuracies of the networks at both stages of the algorithm offered encouraging results, as well as indicates a promising potential for this enhanced approach during field-based condition monitoring of critical rotating machines. Full article

(This article belongs to the Special Issue Fault Detection, Diagnosis, and Recovery: Concept, Modeling, and Optimization)

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22 pages, 5766 KiB

Open AccessEditor’s ChoiceArticle

Implementing and Visualizing ISO 22400 Key Performance Indicators for Monitoring Discrete Manufacturing Systems

by Borja Ramis Ferrer, Usman Muhammad, Wael M. Mohammed and José L. Martínez Lastra

Machines 2018, 6(3), 39; https://doi.org/10.3390/machines6030039 - 01 Sep 2018

Cited by 33 | Viewed by 8075

Abstract

The employment of tools and techniques for monitoring and supervising the performance of industrial systems has become essential for enterprises that seek to be more competitive in today’s market. The main reason is the need for validating tasks that are executed by systems, [...] Read more.

The employment of tools and techniques for monitoring and supervising the performance of industrial systems has become essential for enterprises that seek to be more competitive in today’s market. The main reason is the need for validating tasks that are executed by systems, such as industrial machines, which are involved in production processes. The early detection of malfunctions and/or improvable system values permits the anticipation to critical issues that may delay or even disallow productivity. Advances on Information and Communication Technologies (ICT)-based technologies allows the collection of data on system runtime. In fact, the data is not only collected but formatted and integrated in computer nodes. Then, the formatted data can be further processed and analyzed. This article focuses on the utilization of standard Key Performance Indicators (KPIs), which are a set of parameters that permit the evaluation of the performance of systems. More precisely, the presented research work demonstrates the implementation and visualization of a set of KPIs defined in the ISO 22400 standard-Automation systems and integration, for manufacturing operations management. The approach is validated within a discrete manufacturing web-based interface that is currently used for monitoring and controlling an assembly line at runtime. The selected ISO 22400 KPIs are described within an ontology, which the description is done according to the data models included in the KPI Markup Language (KPIML), which is an XML implementation developed by the Manufacturing Enterprise Solutions Association (MESA) international organization. Full article

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22 pages, 2176 KiB

Open AccessEditor’s ChoiceArticle

Machine Learning Applications on Agricultural Datasets for Smart Farm Enhancement

by Fabrizio Balducci, Donato Impedovo and Giuseppe Pirlo

Machines 2018, 6(3), 38; https://doi.org/10.3390/machines6030038 - 01 Sep 2018

Cited by 138 | Viewed by 18703

Abstract

This work aims to show how to manage heterogeneous information and data coming from real datasets that collect physical, biological, and sensory values. As productive companies—public or private, large or small—need increasing profitability with costs reduction, discovering appropriate ways to exploit data that [...] Read more.

This work aims to show how to manage heterogeneous information and data coming from real datasets that collect physical, biological, and sensory values. As productive companies—public or private, large or small—need increasing profitability with costs reduction, discovering appropriate ways to exploit data that are continuously recorded and made available can be the right choice to achieve these goals. The agricultural field is only apparently refractory to the digital technology and the “smart farm” model is increasingly widespread by exploiting the Internet of Things (IoT) paradigm applied to environmental and historical information through time-series. The focus of this study is the design and deployment of practical tasks, ranging from crop harvest forecasting to missing or wrong sensors data reconstruction, exploiting and comparing various machine learning techniques to suggest toward which direction to employ efforts and investments. The results show how there are ample margins for innovation while supporting requests and needs coming from companies that wish to employ a sustainable and optimized agriculture industrial business, investing not only in technology, but also in the knowledge and in skilled workforce required to take the best out of it. Full article

(This article belongs to the Special Issue Multi-Body System Dynamics: Monitoring, Simulation and Control)

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19 pages, 1186 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Development of a Methodology for Condition-Based Maintenance in a Large-Scale Application Field

by Marco Cocconcelli, Luca Capelli, Jacopo Cavalaglio Camargo Molano and Davide Borghi

Machines 2018, 6(2), 17; https://doi.org/10.3390/machines6020017 - 16 Apr 2018

Cited by 12 | Viewed by 6153

Abstract

This paper describes a methodology, developed by the authors, for condition monitoring and diagnostics of several critical components in the large-scale applications with machines. For industry, the main target of condition monitoring is to prevent the machine stopping suddenly and thus avoid economic [...] Read more.

This paper describes a methodology, developed by the authors, for condition monitoring and diagnostics of several critical components in the large-scale applications with machines. For industry, the main target of condition monitoring is to prevent the machine stopping suddenly and thus avoid economic losses due to lack of production. Once the target is reached at a local level, usually through an R&D project, the extension to a large-scale market gives rise to new goals, such as low computational costs for analysis, easily interpretable results by local technicians, collection of data from worldwide machine installations, and the development of historical datasets to improve methodology, etc. This paper details an approach to condition monitoring, developed together with a multinational corporation, that covers all the critical points mentioned above. Full article

(This article belongs to the Special Issue Machinery Condition Monitoring and Industrial Analytics)

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17 pages, 4950 KiB

Open AccessEditor’s ChoiceArticle

The Setup Design for Selective Laser Sintering of High-Temperature Polymer Materials with the Alignment Control System of Layer Deposition

by Alexey Nazarov, Innokentiy Skornyakov and Igor Shishkovsky

Machines 2018, 6(1), 11; https://doi.org/10.3390/machines6010011 - 05 Mar 2018

Cited by 10 | Viewed by 7250

Abstract

This paper presents the design of an additive setup for the selective laser sintering (SLS) of high-temperature polymeric materials, which is distinguished by an original control system for aligning the device for depositing layers of polyether ether ketone (PEEK) powder. The kinematic and [...] Read more.

This paper presents the design of an additive setup for the selective laser sintering (SLS) of high-temperature polymeric materials, which is distinguished by an original control system for aligning the device for depositing layers of polyether ether ketone (PEEK) powder. The kinematic and laser-optical schemes are given. The main cooling circuits are described. The proposed technical and design solutions enable conducting the SLS process in different types of high-temperature polymer powders. The principles of the device adjustment for depositing powder layers based on an integral thermal analysis are disclosed. The PEEK sinterability was shown on the designed installation. The physic-mechanical properties of the tested 3D parts were evaluated in comparison with the known data and showed an acceptable quality. Full article

(This article belongs to the Special Issue Process Innovation in Digital Manufacturing)

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17 pages, 5261 KiB

Open AccessEditor’s ChoiceArticle

Design Procedure for High-Speed PM Motors Aided by Optimization Algorithms

by Francesco Cupertino, Riccardo Leuzzi, Vito Giuseppe Monopoli and Giuseppe Leonardo Cascella

Machines 2018, 6(1), 5; https://doi.org/10.3390/machines6010005 - 11 Feb 2018

Cited by 10 | Viewed by 4628

Abstract

This paper considers the electromagnetic and structural co-design of superficial permanent magnet synchronous machines for high-speed applications, with the aid of a Pareto optimization procedure. The aim of this work is to present a design procedure for the afore-mentioned machines that relies on [...] Read more.

This paper considers the electromagnetic and structural co-design of superficial permanent magnet synchronous machines for high-speed applications, with the aid of a Pareto optimization procedure. The aim of this work is to present a design procedure for the afore-mentioned machines that relies on the combined used of optimization algorithms and finite element analysis. The proposed approach allows easy analysis of the results and a lowering of the computational burden. The proposed design method is presented through a practical example starting from the specifications of an aeronautical actuator. The design procedure is based on static finite element simulations for electromagnetic analysis and on analytical formulas for structural design. The final results are validated through detailed transient finite element analysis to verify both electromagnetic and structural performance. The step-by-step presentation of the proposed design methodology allows the reader to easily adapt it to different specifications. Finally, a comparison between a distributed-winding (24 slots) and a concentrated-winding (6 slots) machine is presented demonstrating the advantages of the former winding arrangement for high-speed applications. Full article

(This article belongs to the Special Issue High Speed Motors and Drives: Design, Challenges and Applications)

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