Machines

Open AccessArticle

Scheme of Operation for Multi-Robot Systems with Decision-Making Based on Markov Chains for Manipulation by Caged Objects

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Daniel Arreguín-Jasso

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Anand Sanchez-Orta

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Hussain Alazki

Machines 2023, 11(4), 442; https://doi.org/10.3390/machines11040442 - 31 Mar 2023

Abstract

This paper presents the design of a new control scheme for a group of omnidirectional robots in a multi-robot system operating in an environment with obstacles. The control scheme uses a decision agent based on discrete-time Markov chains and takes into account the [...] Read more.

This paper presents the design of a new control scheme for a group of omnidirectional robots in a multi-robot system operating in an environment with obstacles. The control scheme uses a decision agent based on discrete-time Markov chains and takes into account the state of the system, obstacle positions, and geometries to manipulate targets, providing robustness against measurement uncertainties. The decision process is dynamic, with state information updating at each time step and tasks being executed based on the hierarchy determined by quadratic hierarchical programming. The system’s stability in the mean-square sense is analyzed through the study of a closed-loop stochastic system, and the effectiveness of the proposed control scheme is demonstrated through numerical simulations, including a comparative analysis with a finite-state machine decision agent. Full article

(This article belongs to the Special Issue Advanced Motion Control of Multiple Robots)

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Open AccessArticle

A Wearable Upper Limb Exoskeleton for Intuitive Teleoperation of Anthropomorphic Manipulators

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Machines 2023, 11(4), 441; https://doi.org/10.3390/machines11040441 - 30 Mar 2023

Abstract

Teleoperation technology combines the strength and accuracy of robots with the perception and cognition abilities of human experts, allowing the robots to work as an avatar of the operator in dangerous environments. The motion compatibility and intuitiveness of the human–machine interface directly affect [...] Read more.

Teleoperation technology combines the strength and accuracy of robots with the perception and cognition abilities of human experts, allowing the robots to work as an avatar of the operator in dangerous environments. The motion compatibility and intuitiveness of the human–machine interface directly affect the quality of teleoperation. However, many motion capture methods require special working environments or need bulky mechanisms. In this research, we proposed a wearable, lightweight, and passive upper limb exoskeleton, which takes intuitiveness and human-machine compatibility as a major concern. The upper limb pose estimation and teleoperation mapping control methods based on the exoskeleton are also discussed. Experimental results showed that by the help of the upper limb exoskeleton, people can achieve most areas of the normal range of motion. The proposed mapping control methods were verified on a 14-DOF anthropomorphic manipulator and showed good performance in teleoperation tasks. Full article

(This article belongs to the Section Mechatronic and Intelligent Machines)

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Open AccessArticle

A Numerical Approach to Characterize the Efficiency of Cyclone Separator

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Yu Rim Kang

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Jae B. Kwak

Machines 2023, 11(4), 440; https://doi.org/10.3390/machines11040440 - 29 Mar 2023

Abstract

Cyclone separators are active filtering devices suitable for a variety of industrial applications from conventional cutting oil pumps to recycling liquids. Since the vortex flow inside cyclones is highly complicated, the performance and flow patterns of these filters should be thoroughly researched. Liquid–solid [...] Read more.

Cyclone separators are active filtering devices suitable for a variety of industrial applications from conventional cutting oil pumps to recycling liquids. Since the vortex flow inside cyclones is highly complicated, the performance and flow patterns of these filters should be thoroughly researched. Liquid–solid cyclones mostly use water. Numerical studies on cyclones using higher-viscosity oils are limited. In this study, a liquid–solid cyclone injected with medium-viscosity cutting oil containing various sized-particles was comprehensively investigated. The reliability of computational fluid dynamics (CFD) methods was verified through a comparison with the experimental results. Three models with different geometries were considered for the analysis. One model was used for CFD verification. The other two models involved adding sockets for hopper length extension and changing the shape of the bottom of the hopper. The models that changed the shape of the hopper, thus directly affecting the cyclone performance, were investigated, and each model was qualitatively compared using a validated method. In addition, particle separation efficiency was evaluated by focusing on the velocity distribution to quantitatively confirm the influence of changing the shape of the hopper. The tangential velocity was determined to be similar across all three models, while the axial velocity was different and the change in the velocity of transport of the particles affected the filter function. Full article

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

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Open AccessArticle

Effect of Coated Composite Micro–Texture Tool on Cutting Shape and Cutting Force during Aluminum Alloy Cutting

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Machines 2023, 11(4), 439; https://doi.org/10.3390/machines11040439 - 29 Mar 2023

Abstract

Aluminum alloy materials are very difficult to break in the processing process; chip accumulation leads to poor processing stability. In this paper, a coated composite micro–textured tool is presented. The influence of coated composite micro–textured tool on chip shape and cutting force under [...] Read more.

Aluminum alloy materials are very difficult to break in the processing process; chip accumulation leads to poor processing stability. In this paper, a coated composite micro–textured tool is presented. The influence of coated composite micro–textured tool on chip shape and cutting force under the same cutting parameters is studied. Firstly, the combination of cutting force and cutting temperature is optimized based on cutting test. Secondly, combined with the finite element simulation technology, three kinds of composite micro–texture tools are tested to determine the same cutting parameters, tools and workpiece materials, and optimize the composite micro–texture combination from the angle of chip shape, cutting temperature and cutting force. Finally, on the basis of optimizing the microstructure combination, the optimization of the cutting performance of aluminum alloy by coating material is studied. It was found that the chip was more easily broken in the composite microstructure when two tools were used. The cutting force decreased by 25% and the cutting temperature decreased by 9.09% compared with the non–micro–texture tools. The cutting temperature and cutting force decreased by 3% and 4.99% compared with those of uncoated composite microstructure. Full article

(This article belongs to the Topic Advanced Manufacturing and Surface Technology)

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Open AccessArticle

Optimization Method of Speed Ratio for Power-Shift Transmission of Agricultural Tractor

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Machines 2023, 11(4), 438; https://doi.org/10.3390/machines11040438 - 29 Mar 2023

Abstract

The speed ratio parameters of transmission are crucial factors that affect a vehicle’s power, economy, and comfort. Due to the complex working conditions, multiple working modes, and wide range of speed ratios of agricultural tractors, designing and optimizing speed ratio parameters in power-shift [...] Read more.

The speed ratio parameters of transmission are crucial factors that affect a vehicle’s power, economy, and comfort. Due to the complex working conditions, multiple working modes, and wide range of speed ratios of agricultural tractors, designing and optimizing speed ratio parameters in power-shift transmissions is a challenging task. This paper proposes a transmission speed ratio optimization method based on the life cycle speed utilization rate of general-purpose agricultural tractors. The speed ratio parameters are optimized and solved using the genetic algorithm, with multi-gear power-shift transmissions in agricultural tractors as the research subject. The optimization results and simulation analysis show that the optimized speed ratio has more and denser gears in the common operating speed range while ensuring the general-purpose agricultural tractors’ use requirements. Compared to commonly used geometric series speed ratios, tractors using the optimized speed ratio parameters in this paper can significantly improve fuel economy. Most importantly, this provides a practical method reference for optimizing speed ratios in multi-gear gearboxes with complex structures. Full article

(This article belongs to the Section Vehicle Engineering)

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Open AccessArticle

Design and Control of an Energy-Efficient Speed Regulating Method for Pump-Controlled Motor System under Negative Loads

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Machines 2023, 11(4), 437; https://doi.org/10.3390/machines11040437 - 29 Mar 2023

Abstract

Pump-controlled motor hydrostatic system (PCMH) is widely applied for rotary driving in heavy industry and construction machinery due to its high-power density and efficient speed regulation performance. However, the contradiction of the PCMH system between energy saving and speed control appears when it [...] Read more.

Pump-controlled motor hydrostatic system (PCMH) is widely applied for rotary driving in heavy industry and construction machinery due to its high-power density and efficient speed regulation performance. However, the contradiction of the PCMH system between energy saving and speed control appears when it deals with negative loads. To address this contradiction, an energy-efficient speed regulating method based on electro-proportional counterbalance valves (EPCBVs) is designed, along with the corresponding controller. The working principle of the proposed scheme is that under a negative-load operation mode, determined by the supervisory controller according to system states and reference inputs, the speed of the hydraulic motor is controlled by a velocity controller through adjustment of the control signal of the EPCBV, and that the inlet pressure of the hydraulic motor is maintained at a defined low point by a pressure controller through pump displacement control. Comparative experiments between the EPCBV and T-CBV (a PCMH system based on a typical CBV) systems are conducted to verify the superiority of the proposed scheme in energy-efficient speed regulation under negative loads. The results show that, in most of the working conditions, the EPCBV system shows better adaption than the T-CBV system to varying negative loads and maintains higher stability than the T-CBV. Moreover, the speed accuracy of the EPCBV system can be maintained above 95%, which is greater than that of the T-CBV system, varying from 48% to 90%. Furthermore, the maximum power consumption is only about 4 Kw and is far less than that of the T-CBV system, which is about 13.79 Kw. The power-saving ratio changes from 20% to 82%, but it goes beyond 50% in most of the working conditions. The proposed method is easy to implement in practical application and is of great significance to the PCMH system for energy-efficient speed control under negative loads. Full article

(This article belongs to the Section Electrical Machines and Drives)

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Open AccessArticle

Design and Experiment of Apple Foam Net Sleeve Packaging Machine with Posture Adjustment Function

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Machines 2023, 11(4), 436; https://doi.org/10.3390/machines11040436 - 29 Mar 2023

Abstract

Background: In this study, an apple foam net packing machine is designed to improve the efficiency of apple foam net packing, reduce the intensity of manual work, and meet the market demand for diverse forms of apple packing. Methods: Based on the analysis [...] Read more.

Background: In this study, an apple foam net packing machine is designed to improve the efficiency of apple foam net packing, reduce the intensity of manual work, and meet the market demand for diverse forms of apple packing. Methods: Based on the analysis of apple shape characteristics, a secondary posture adjustment method for apples with a vertical posture adjustment mechanism and a side posture adjustment mechanism is proposed. Based on the observation of human hand-set nets and the analysis of the mechanical characteristics of nets, a dual-system net opening method combining a net slackening system and a net opening system is proposed. Results: The experiment shows that: the apple foam net sleeve packing machine can reach 99% of the apple’s posture adjustment rate, the net opening rate can reach 99%, and the packing rate can reach 98.10%. The packing speed is 10 s/pcs, and the packing efficiency is 355–365 pcs/h. The length of the fused mesh net sleeve is mainly distributed between 138 and 143 mm, which accounts for approximately 80% of the total number of samples. Conclusions: The apples packed by this machine are neatly packaged according to specifications. It can improve the efficiency of apple foam net sleeve packing and replace manual work. Full article

(This article belongs to the Special Issue New Trends in Robotics and Automation)

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Open AccessArticle

Integrated Optimization Model for Maintenance Policies and Quality Control Parameters for Multi-Component System

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Emad Hashiem Abualsauod

Machines 2023, 11(4), 435; https://doi.org/10.3390/machines11040435 - 29 Mar 2023

Abstract

The practical applications of integrated maintenance policies and quality for a multi-component system are more complicated, still rare, and incomplete to meet the requirements of Industry 4.0. Therefore, this work aims to extend the integration economic model for optimizing maintenance policies and quality [...] Read more.

The practical applications of integrated maintenance policies and quality for a multi-component system are more complicated, still rare, and incomplete to meet the requirements of Industry 4.0. Therefore, this work aims to extend the integration economic model for optimizing maintenance policies and quality control parameters by incorporating the Taguchi loss function for a multi-component system. An optimization model is developed based on preventive maintenance, corrective maintenance policies, and quality control parameters with the CUSUM (Cumulative Sum) chart, which is widely used for detecting small shifts in the process mean. The model was developed to minimize the expected total cost per unit of time and to obtain the optimal values of decision variables: the size of samples, sample frequency, decision interval, coefficient of the CUSUM chart, and preventive and corrective maintenance intervals. The solution steps were employed by selecting a case study in the Alahlia Mineral Water Company (AMWC). Then, the design of experiments based on one-factor-at-a-time was used to evaluate the effect of selected decision variables on the expected total cost. Finally, sensitivity analysis was performed on the selected decision variables to demonstrate the robustness of the developed model. A predictive maintenance plan was developed based on the optimal value of preventive maintenance interval, and the results showed that the performance of the maintenance plan realizes the full potential of the integrated model. In addition, the case study results indicate that the extended integrated model for multicomponent is the new standard for the quality production of multi-component systems in future works. Full article

(This article belongs to the Special Issue Machine Learning for Predictive Maintenance)

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Open AccessArticle

Enhanced Tyre Pressure Monitoring System for Nitrogen Filled Tyres Using Deep Learning

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Arun Balaji Muturatnam

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Naveen Venkatesh Sridharan

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Anoop Prabhakaranpillai Sreelatha

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Sugumaran Vaithiyanathan

Machines 2023, 11(4), 434; https://doi.org/10.3390/machines11040434 - 29 Mar 2023

Abstract

Tyre pressure monitoring systems (TPMS) are electronic devices that monitor tyre pressure in vehicles. Existing systems rely on wheel speed sensors or pressure sensors. They rely on batteries and radio transmitters, which add to the expense and complexity. There are two types of [...] Read more.

Tyre pressure monitoring systems (TPMS) are electronic devices that monitor tyre pressure in vehicles. Existing systems rely on wheel speed sensors or pressure sensors. They rely on batteries and radio transmitters, which add to the expense and complexity. There are two types of basic tyres: non-pneumatic and pneumatic tyres. Non-pneumatic tyres lack air and combine the tyre and wheel into a single unit. When it comes to noise reduction, durability, and shock absorption, pneumatic tyres are more valuable than non-pneumatic tyres. In this study, nitrogen-filled pneumatic tyres were considered due to the uniform pressure management property. Additionally, nitrogen has less of an effect on thermal expansion than regular air-filled tyres. This work aimed to offer a deep learning approach for TPMS. An accelerometer captured vertical vibrations from a moving vehicle’s wheel hub, which were then converted in the form of vibration plots and categorized using pretrained networks. The most popular pretrained networks such as AlexNet, GoogLeNet, ResNet-50 and VGG-16 were employed in this study. From these pretrained networks, the best-performing pretrained network was determined and suggested for TPMS by varying the hyperparameters such as learning rate (LR), batch size (BS), train-test split ratio (TR), and solver (SR). Findings: A higher classification accuracy of 97.20% was obtained while using ResNet-50. Full article

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

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Open AccessArticle

A Space-Time Absolute Nodal Coordinate Formulation Cable Element and the Study of Its Accuracy and Efficiency

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Machines 2023, 11(4), 433; https://doi.org/10.3390/machines11040433 - 29 Mar 2023

Abstract

In this paper, a space-time absolute nodal coordinate formulation cable (SAC) element forming technique based on the Lagrange family of shape functions is proposed. Two distinct SAC elements, each with a distinct spatial shape function, have been generated by this method. Moreover, the [...] Read more.

In this paper, a space-time absolute nodal coordinate formulation cable (SAC) element forming technique based on the Lagrange family of shape functions is proposed. Two distinct SAC elements, each with a distinct spatial shape function, have been generated by this method. Moreover, the external forces such as the bending moment and the air resistance formula have been accounted for. The Lagrange multiplier method, along with the concepts of replacement constraint and supplementary constraint, has been employed to provide a solution for the dynamics of constrained mechanical systems. Additionally, a constraint conversion strategy has been suggested. The solver has been constructed through Hamilton’s law of varying action. The space-time finite element method is used to solve dynamic problems, employing the Newton algorithm and quasi-Newton algorithm. The accuracy and efficiency of the solution has been verified by three simulations and one experiment. The circle-bending static simulation and the double-ended velocity impact dynamic simulation demonstrate the accuracy of the two elements. The correlation between statics and dynamics has been studied for different discretization methods and different solvers’ calculation accuracy and efficiency. Different modeling methods, time steps, order and the application of the quasi-Newton method all have a bearing on the efficiency of the solution. Finally, a comparison with an experiment in the free-pendulum simulation reveals the capability of this model to simulate dynamic problems with air resistance. Full article

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

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Open AccessArticle

Development and Testing of a Self-Propelled Machine for Combined Potato Harvesting and Residual Plastic Film Retrieval

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Petru Aurelian Simionescu

Machines 2023, 11(4), 432; https://doi.org/10.3390/machines11040432 - 28 Mar 2023

Abstract

A self-propelled machine for combined potato harvesting and residual plastic film retrieval is presented in this paper. The machine was designed collaboratively and built at the College of Mechano-Electronic Engineering of Gansu Agricultural University. It is intended for slow slope and horizontal terraces [...] Read more.

A self-propelled machine for combined potato harvesting and residual plastic film retrieval is presented in this paper. The machine was designed collaboratively and built at the College of Mechano-Electronic Engineering of Gansu Agricultural University. It is intended for slow slope and horizontal terraces in hilly and mountainous areas of Northwest China, where regular-size harvesters cannot operate. The machine can realize the combined operations of potato digging, potato separation from soil and plastic film, potato collection and bagging, and residual plastic film retrieval. Through engineering analyses, the main systems of the machine were calculated, and their operating parameters were estimated. These include the digging and lifting device, the potato–plastic-film separation device, and the residual plastic film retrieval device. Field tests were performed at a 0.5 m/s driving speed of the machine, while the linear speed of the lifting chain of the digging and lifting device was 1.5 m/s, the tilting angle of the conveying chain of the potato and plastic film separation device was 50°, its linear speed was 0.6 m/s, and the linear speed of the lifting screen of the circulating lifting device was 0.7 m/s. With these settings, the average productivity of the machine was 0.12 ha/h. The loss rate, damage rate, and potato bruising rate were 1.8%, 1.4%, and 2.8%, respectively; the potato impurity rate was 3.6%; and the residual plastic film retrieval rate was 83%—all above industry standards. This research provides a solution to the problem of mechanized potato harvesting and plastic mulch retrieval on small, slopped plots of land in Northwest China and in other parts of the world where similar conditions exist. Full article

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

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Open AccessArticle

Multi-Robot Task Scheduling for Consensus-Based Fault-Resilient Intelligent Behavior in Smart Factories

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Vivian Cremer Kalempa

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Luis Piardi

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Marcelo Limeira

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Andre Schneider de Oliveira

Machines 2023, 11(4), 431; https://doi.org/10.3390/machines11040431 - 28 Mar 2023

Abstract

In smart factories, several mobile and autonomous robots are being utilized in warehouses to reduce overhead and operating costs. In this context, this paper presents a consensus-based fault-resilient intelligent mechanism called Consensual Fault-Resilient Behavior (CFRB). The proposed approach is based on three hierarchical [...] Read more.

In smart factories, several mobile and autonomous robots are being utilized in warehouses to reduce overhead and operating costs. In this context, this paper presents a consensus-based fault-resilient intelligent mechanism called Consensual Fault-Resilient Behavior (CFRB). The proposed approach is based on three hierarchical plans: imposition, negotiation, and consensus. Fault resilience is achieved using the collective behavior of a multi-robot system that applies ternary decisions based on these plans. The difference between this paper and our previous work is on the consensual level. As it is suitable for the analysis and design of coordinated behavior between autonomous robots, the consensus plan is restructured and enhanced. The proposed approach is tested and evaluated in a virtual warehouse based on a real environment. In addition, it is compared with other current approaches, and the results are presented, demonstrating its efficiency. Full article

(This article belongs to the Special Issue Recent Advances in Mobile Robots)

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Open AccessArticle

A Genetic Algorithm-Controlled Solar Tracker Robot with Increased Precision Due to Evolution

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Roland Szabo

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Radu-Stefan Ricman

Machines 2023, 11(4), 430; https://doi.org/10.3390/machines11040430 - 28 Mar 2023

Abstract

The aim of this paper is to present the genetic algorithm used in programming a solar tracker robot. The solar tracker robot can be used to increase the efficiency of solar panels by rotating them toward the Sun. When the efficiency of solar [...] Read more.

The aim of this paper is to present the genetic algorithm used in programming a solar tracker robot. The solar tracker robot can be used to increase the efficiency of solar panels by rotating them toward the Sun. When the efficiency of solar panels is increased, they can reduce the space occupied by them. Efficiency can also be increased by genetic algorithms, where a solar panel can evolve and thus track the Sun more precisely. The genetic algorithm implemented in the solar tracker is the main focus of this paper. The genetic algorithm is presented with a flow chart and formulas. After this, the system is implemented on a solar tracker robot and validated with real experiments. The solar tracker robot algorithm is implemented in the C language on a microcontroller built on an FPGA platform. Full article

(This article belongs to the Section Mechatronic and Intelligent Machines)

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Open AccessArticle

Aerodynamic Performance of V8 Octorotor MAV with Different Rotor Configurations in Hover

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Yao Lei

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Zhicheng Feng

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Chensong Ma

Machines 2023, 11(4), 429; https://doi.org/10.3390/machines11040429 - 27 Mar 2023

Abstract

A new multirotor aerial vehicle with two rotor arms formed in a V-shape configuration is introduced in this paper. To figure out the aerodynamic interference effects between rotors as an implication of the control method, this paper discusses the aerodynamic performance of the [...] Read more.

A new multirotor aerial vehicle with two rotor arms formed in a V-shape configuration is introduced in this paper. To figure out the aerodynamic interference effects between rotors as an implication of the control method, this paper discusses the aerodynamic performance of the V8 Octorotor MAV with different rotor spacing using both experiments and simulations. A hovering experiment platform is applied to obtain the thrust, power consumption and rotational speed. PL (power loading) is promoted to characterize the aerodynamic performance of the V8 Octorotor MAV. The velocity vector, streamline and turbulent vortices’ distribution of the V8 Octorotor MAV are presented as the simulation results, which indicates that turbulence intensity generated by the MAV dissipates faster in a large rotor spacing. Therefore, rotor vibration is reduced with an increased hovering stability, and the power loading is much improved at G3 (1.2D–1.4D–1.6D–1.8D) with a better aerodynamic performance both with a thrust increment and power decrement. Full article

(This article belongs to the Special Issue Optimal Design of Aircraft)

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Open AccessArticle

Conical Grinding Wheel Ultrasonic-Assisted Grinding Micro-Texture Surface Formation Mechanism

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Machines 2023, 11(4), 428; https://doi.org/10.3390/machines11040428 - 27 Mar 2023

Abstract

The rotating ultrasonic-assisted grinding (RUAG) experiment of the conical grinding wheel generated the intermittent pit-shaped micro-texture on the surface of the workpiece, reducing thermal damage and improving the lubrication characteristics compared with conventional grinding (CG). To further optimize the surface properties, this paper [...] Read more.

The rotating ultrasonic-assisted grinding (RUAG) experiment of the conical grinding wheel generated the intermittent pit-shaped micro-texture on the surface of the workpiece, reducing thermal damage and improving the lubrication characteristics compared with conventional grinding (CG). To further optimize the surface properties, this paper studied the formation mechanism of micro-texture. This study used as basis the theory that micro-debris volume equals the macroscopic material removal one to establish the mathematical equation of grinding depth. Thereafter, formulas of micro-texture feature parameters, including pit length, pit depth, and texture spacing were deduced. The solved microscopic grinding depth was alternatingly positive and negative, indicating that the alternating separation between the grinding grain and workpiece caused intermittent pits in the grinding. Through response surface analysis (RSA), this paper analyzed the relationships among macroscopic grinding depth, micro-texture feature parameters, and machining parameters (i.e., amplitude, feed rate, and rotational speed). Single-factor experiments of machining parameters, with finite element simulation and experiment methods, were performed to verify the theoretical micro-texture features. The simulated program formed three-dimensional surfaces with micro-textures. Their measurement results were consistent with the theoretical ones. Experimental results proved that the range of pit length covers the theoretical ones, further verifying the accuracy of the grinding depth model. For this grinding wheel, the 8–10 μm amplitude was optimal for better roughness, lubrication, and thermal damage. Roughness was improved when increasing the rotational speed or reducing the feed rate based on the experiment. If the rotational speed and feed rate exceed the limiting values, then continuous grinding will break down the abrasive grains and even damage the cubic boron nitride (CBN) coating. Experimental results likewise showed that the pit shape was closely related to the surface properties, which deserves further investigation. Full article

(This article belongs to the Topic Advanced Manufacturing and Surface Technology)

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Open AccessArticle

Dynamic Simulation of Multiple Launch Rocket System Marching Fire Based on the Fuzzy Adaptive Sliding Mode Control

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Machines 2023, 11(4), 427; https://doi.org/10.3390/machines11040427 - 27 Mar 2023

Abstract

This paper presents a servo control method for the multiple launch rocket system (MLRS) launcher during marching fire operations. The MLRS, being a complex nonlinear system, presents challenges in designing its servo controller. To address this, we introduce the fuzzy adaptive sliding mode [...] Read more.

This paper presents a servo control method for the multiple launch rocket system (MLRS) launcher during marching fire operations. The MLRS, being a complex nonlinear system, presents challenges in designing its servo controller. To address this, we introduce the fuzzy adaptive sliding mode control (FASMC) approach. The permanent magnet synchronous motor (PMSM) and controller of the MLRS were simulated in the MATLAB/Simulink environment. The dynamic model of the MLRS during marching fire was established using multi-body system theory, vehicle mechanics, and launch dynamics. The dynamic model was then integrated with the FASMC-based controller using the Adams/View module. Numerical calculations were performed to demonstrate the control performance and the effectiveness and applicability of the proposed approach were validated through a comparison experiment between FASMC and other common control methods. Full article

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Open AccessArticle

Boundary Scenario Generation for HAVs Based on Classification and Local Sampling

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Machines 2023, 11(4), 426; https://doi.org/10.3390/machines11040426 - 27 Mar 2023

Abstract

High-level Automated Vehicles (HAVs) are expected to improve traffic safety significantly. However, verifying and evaluating HAVs remains an open problem. Scenario-based testing is a promising method for HAV testing. Boundary scenarios exist around the performance boundary between critical and non-critical scenarios. Testing HAVs [...] Read more.

High-level Automated Vehicles (HAVs) are expected to improve traffic safety significantly. However, verifying and evaluating HAVs remains an open problem. Scenario-based testing is a promising method for HAV testing. Boundary scenarios exist around the performance boundary between critical and non-critical scenarios. Testing HAVs in these boundary scenarios is crucial to investigate why collisions cannot be avoided due to small changes in scenario parameters. This study proposes a methodology to generate diverse boundary scenarios to test HAVs. First, an approach is proposed to obtain at least one High-Performance Classifier (HPC) based on two classification algorithms that iteratively guide each other to find uncertain scenarios to improve their performance. Then, the HPC is exploited to find candidate scenarios highly likely to be boundary scenarios. To increase the efficiency of candidate scenario generation, a strategy based on local sampling is presented to find more diverse candidate scenarios based on a small number of them. Numerical experiments show that the HPCs acquired by the method proposed in this study can achieve a classification accuracy of 98% and 99% for random car-following and cut-in scenarios, respectively. Moreover, more than 86% of 271,744 candidate cut-in scenarios derived by local sampling are near the performance boundary. Full article

(This article belongs to the Section Vehicle Engineering)

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Open AccessArticle

Implementing Digital Twins That Learn: AI and Simulation Are at the Core

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Bahar Biller

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Stephan Biller

Machines 2023, 11(4), 425; https://doi.org/10.3390/machines11040425 - 27 Mar 2023

Abstract

As companies are trying to build more resilient supply chains using digital twins created by smart manufacturing technologies, it is imperative that senior executives and technology providers understand the crucial role of process simulation and AI in quantifying the uncertainties of these complex [...] Read more.

As companies are trying to build more resilient supply chains using digital twins created by smart manufacturing technologies, it is imperative that senior executives and technology providers understand the crucial role of process simulation and AI in quantifying the uncertainties of these complex systems. The resulting digital twins enable users to replay history, gain predictive visibility into the future, and identify corrective actions to optimize future performance. In this article, we define process digital twins and their four foundational elements. We discuss how key digital twin functions and enabling AI and simulation technologies integrate to describe, predict, and optimize supply chains for Industry 4.0 implementations. Full article

(This article belongs to the Special Issue Advances in Digital Twins for Manufacturing)

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Open AccessEditorial

Fault Diagnosis and Health Management of Power Machinery

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Machines 2023, 11(4), 424; https://doi.org/10.3390/machines11040424 - 27 Mar 2023

Abstract

Power-machinery systems are widely used in various industries, including manu-facturing, energy production, transportation, and infrastructure [...] Full article

(This article belongs to the Special Issue Fault Diagnosis and Health Management of Power Machinery)

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