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399 KiB

Open AccessArticle

A Practical Tuning Method for the Robust PID Controller with Velocity Feed-Back

by Emre Sariyildiz, Haoyong Yu and Kouhei Ohnishi

Machines 2015, 3(3), 208-222; https://doi.org/10.3390/machines3030208 - 20 Aug 2015

Cited by 21 | Viewed by 13127

Proportional-Integral-Derivative (PID) control is the most widely used control method in industrial and academic applications due to its simplicity and efficiency. Several different control methods/algorithms have been proposed to tune the gains of PID controllers. However, the conventional tuning methods do not have [...] Read more.

Proportional-Integral-Derivative (PID) control is the most widely used control method in industrial and academic applications due to its simplicity and efficiency. Several different control methods/algorithms have been proposed to tune the gains of PID controllers. However, the conventional tuning methods do not have sufficient performance and simplicity for practical applications, such as robotics and motion control. The performance of motion control systems may significantly deteriorate by the nonlinear plant uncertainties and unknown external disturbances, such as inertia variations, friction, external loads, etc., i.e., there may be a significant discrepancy between the simulation and experiment if the robustness is not considered in the design of PID controllers. This paper proposes a novel practical tuning method for the robust PID controller with velocity feed-back for motion control systems. The main advantages of the proposed method are the simplicity and efficiency in practical applications, i.e., a high performance robust motion control system can be easily designed by properly tuning conventional PID controllers. The validity of the proposal is verified by giving simulation and experimental results. Full article

(This article belongs to the Special Issue Advances in Control Engineering)

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2010 KiB

Open AccessArticle

A Novel Approach to the Design of Axial-Flux Switched-Reluctance Motors

by Tim Lambert, Mohammad Biglarbegian and Shohel Mahmud

Machines 2015, 3(1), 27-54; https://doi.org/10.3390/machines3010027 - 03 Mar 2015

Cited by 11 | Viewed by 13859

Abstract

This paper presents the design of a new axial-flux switched-reluctance motor (AFSRM) topology for in-wheel drive vehicle applications. The features of the topology include a short flux path and an outer-rotor configuration. The proposed topology also uses a sintered-lamellar soft magnetic composite core [...] Read more.

This paper presents the design of a new axial-flux switched-reluctance motor (AFSRM) topology for in-wheel drive vehicle applications. The features of the topology include a short flux path and an outer-rotor configuration. The proposed topology also uses a sintered-lamellar soft magnetic composite core material, and permits displacement of the rotor along the suspension axis, which reduces damage to the stator caused by impacts and vibrations. The combination of these features makes this new topology competitive with other in-wheel motors in regard to torque density, durability, and cost. To describe the behaviour of the topology, a model of the topology is developed using a new integral inductance function. That model is used to select the design parameters of an 8/6 AFSRM, for which a fuzzy controller is also developed to control the phase current. Several simulations of the 8/6 AFSRM are performed to calculate its energy conversion efficiency, thermal performance, and torque density, and results indicate that the new AFSRM has a higher energy conversion efficiency, and can produce more torque/kg than other switched-reluctance motors used for in-wheel drive vehicle applications. Full article

(This article belongs to the Special Issue Advances in Control Engineering)

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817 KiB

Open AccessArticle

Limit Cycles in Nonlinear Systems with Fractional Order Plants

by Derek P. Atherton, Nusret Tan, Celaleddin Yeroglu, Gürkan Kavuran and Ali Yüce

Machines 2014, 2(3), 176-201; https://doi.org/10.3390/machines2030176 - 17 Jul 2014

Cited by 13 | Viewed by 7815

Abstract

In recent years, there has been considerable interest in the study of feedback systems containing processes whose dynamics are best described by fractional order derivatives. Various situations have been cited for describing heat flow and aspects of bioengineering, where such models are believed [...] Read more.

In recent years, there has been considerable interest in the study of feedback systems containing processes whose dynamics are best described by fractional order derivatives. Various situations have been cited for describing heat flow and aspects of bioengineering, where such models are believed to be superior. In many situations these feedback systems are not linear and information on their stability and the possibility of the existence of limit cycles is required. This paper presents new results for determining limit cycles using the approximate describing function method and an exact method when the nonlinearity is a relay characteristic. Full article

(This article belongs to the Special Issue Advances in Control Engineering)

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498 KiB

Open AccessArticle

Influence of Control Structures and Load Parameters on Performance of a Pseudo Direct Drive

by Mohammed Bouheraoua, Jiabin Wang and Kais Atallah

Machines 2014, 2(3), 158-175; https://doi.org/10.3390/machines2030158 - 04 Jul 2014

Cited by 10 | Viewed by 9967

Abstract

The paper describes an in-depth and systematic analysis of a pseudo direct drive permanent magnet machine in closed loop control. Due to the torque being transmitted from the high-speed rotor (HSR) to the low-speed rotor (LSR), through a relatively low stiffness magnetic gear [...] Read more.

The paper describes an in-depth and systematic analysis of a pseudo direct drive permanent magnet machine in closed loop control. Due to the torque being transmitted from the high-speed rotor (HSR) to the low-speed rotor (LSR), through a relatively low stiffness magnetic gear with non-linear characteristics, speed oscillations appear in the drive output with a conventional proportional integral (PI) controller. Therefore two candidate controllers have been proposed as an alternative to the PI control and all controllers have been optimally tuned with a genetic algorithm against a defined criterion. Furthermore, closed loop models are established in the complex frequency domain to determine the system damping and the cause of the oscillations. Consequently, the best controller structure that improves the dynamic behaviour of the system in terms of speed tracking and disturbance rejection could be identified, based on the frequency domain analysis. Experimental results are presented to validate the analysis and the proposed control technique. Full article

(This article belongs to the Special Issue Advances in Control Engineering)

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2233 KiB

Open AccessArticle

Control of Adjustable Compliant Actuators

by Berno J.E. Misgeld, Kurt Gerlach-Hahn, Daniel Rüschen, Anake Pomprapa and Steffen Leonhardt

Machines 2014, 2(2), 134-157; https://doi.org/10.3390/machines2020134 - 20 May 2014

Cited by 5 | Viewed by 5575

Abstract

Adjustable compliance or variable stiffness actuators comprise an additional element to elastically decouple the actuator from the load and are increasingly applied to human-centered robotic systems. The advantages of such actuators are of paramount importance in rehabilitation robotics, where requirements demand safe interaction [...] Read more.

Adjustable compliance or variable stiffness actuators comprise an additional element to elastically decouple the actuator from the load and are increasingly applied to human-centered robotic systems. The advantages of such actuators are of paramount importance in rehabilitation robotics, where requirements demand safe interaction between the therapy system and the patient. Compliant actuator systems enable the minimization of large contact forces arising, for example, from muscular spasticity and have the ability to periodically store and release energy in cyclic movements. In order to overcome the loss of bandwidth introduced by the elastic element and to guarantee a higher range in force/torque generation, new actuator designs consider variable or nonlinear stiffness elements, respectively. These components cannot only be adapted to the walking speed or the patient condition, but also entail additional challenges for feedback control. This paper introduces a novel design method for an impedance-based controller that fulfills the control objectives and compares the performance and robustness to a classical cascaded control approach. The new procedure is developed using a non-standard positive-real Η₂ controller design and is applied to a loop-shaping approach. Robust norm optimal controllers are designed with regard to the passivity of the actuator load-impedance transfer function and the servo control problem. Classical cascaded and positive-real Η₂ controller designs are validated and compared in simulations and in a test bench using a passive elastic element of varying stiffness. Full article

(This article belongs to the Special Issue Advances in Control Engineering)

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1338 KiB

Open AccessArticle

Fuzzy Pattern Classification Based Detection of Faulty Electronic Fuel Control (EFC) Valves Used in Diesel Engines

by Umut Tugsal and Sohel Anwar

Machines 2014, 2(2), 99-119; https://doi.org/10.3390/machines2020099 - 07 May 2014

Cited by 1 | Viewed by 6686

Abstract

In this paper, we develop mathematical models of a rotary Electronic Fuel Control (EFC) valve used in a Diesel engine based on dynamic performance test data and system identification methodology in order to detect the faulty EFC valves. The model takes into account [...] Read more.

In this paper, we develop mathematical models of a rotary Electronic Fuel Control (EFC) valve used in a Diesel engine based on dynamic performance test data and system identification methodology in order to detect the faulty EFC valves. The model takes into account the dynamics of the electrical and mechanical portions of the EFC valves. A recursive least squares (RLS) type system identification methodology has been utilized to determine the transfer functions of the different types of EFC valves that were investigated in this study. Both in frequency domain and time domain methods have been utilized for this purpose. Based on the characteristic patterns exhibited by the EFC valves, a fuzzy logic based pattern classification method was utilized to evaluate the residuals and identify faulty EFC valves from good ones. The developed methodology has been shown to provide robust diagnostics for a wide range of EFC valves. Full article

(This article belongs to the Special Issue Advances in Control Engineering)

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736 KiB

Open AccessArticle

Pollutant Emission Validation of a Heavy-Duty Gas Turbine Burner by CFD Modeling

by Roberto Meloni

Machines 2013, 1(3), 81-97; https://doi.org/10.3390/machines1030081 - 16 Oct 2013

Cited by 11 | Viewed by 7495

Abstract

3D numerical combustion simulation in a can burner fed with methane was carried out in order to evaluate pollutant emissions and the temperature field. As a case study, the General Electric Frame 6001B system was considered. The numerical investigation has been performed using [...] Read more.

3D numerical combustion simulation in a can burner fed with methane was carried out in order to evaluate pollutant emissions and the temperature field. As a case study, the General Electric Frame 6001B system was considered. The numerical investigation has been performed using the CFD code named ACE+ Multiphysics (by Esi-Group). The model was validated against the experimental data provided by Cofely GDF SUEZ and related to a real power plant. To completely investigate the stability of the model, several operating conditions were taken into account, at both nominal and partial load. In particular, the influence on emissions of some important parameters, such as air temperature at compressor intake and steam to fuel mass ratio, have been evaluated. The flamelet model and Zeldovich’s mechanism were employed for combustion modeling and NO_x emissions, respectively. With regard to CO estimation, an innovative approach was used to compute the Rizk and Mongia relationship through a user-defined function. Numerical results showed good agreement with experimental data in most of the cases: the best results were obtained in the NO_x prediction, while unburned fuel was slightly overestimated. Full article

(This article belongs to the Special Issue Advances in Control Engineering)

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416 KiB

Open AccessArticle

Multiple Estimation Architecture in Discrete-Time Adaptive Mixing Control

by Simone Baldi

Machines 2013, 1(1), 33-49; https://doi.org/10.3390/machines1010033 - 29 May 2013

Cited by 1 | Viewed by 5219

Abstract

Adaptive mixing control (AMC) is a recently developed control scheme for uncertain plants, where the control action coming from a bank of precomputed controller is mixed based on the parameter estimates generated by an on-line parameter estimator. Even if the stability of the [...] Read more.

Adaptive mixing control (AMC) is a recently developed control scheme for uncertain plants, where the control action coming from a bank of precomputed controller is mixed based on the parameter estimates generated by an on-line parameter estimator. Even if the stability of the control scheme, also in the presence of modeling errors and disturbances, has been shown analytically, its transient performance might be sensitive to the initial conditions of the parameter estimator. In particular, for some initial conditions, transient oscillations may not be acceptable in practical applications. In order to account for such a possible phenomenon and to improve the learning capability of the adaptive scheme, in this paper a new mixing architecture is developed, involving the use of parallel parameter estimators, or multi-estimators, each one working on a small subset of the uncertainty set. A supervisory logic, using performance signals based on the past and present estimation error, selects the parameter estimate to determine the mixing of the controllers. The stability and robustness properties of the resulting approach, referred to as multi-estimator adaptive mixing control (Multi-AMC), are analytically established. Besides, extensive simulations demonstrate that the scheme improves the transient performance of the original AMC with a single estimator. The control scheme and the analysis are carried out in a discrete-time framework, for easier implementation of the method in digital control. Full article

(This article belongs to the Special Issue Advances in Control Engineering)

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Review

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19299 KiB

Open AccessReview

The Multiple Unmanned Air Vehicle Persistent Surveillance Problem: A Review

by Nikhil Nigam

Machines 2014, 2(1), 13-72; https://doi.org/10.3390/machines2010013 - 02 Jan 2014

Cited by 79 | Viewed by 10298

Abstract

Control of autonomous vehicles for applications such as surveillance, search, and exploration has been a topic of great interest over the past two decades. In particular, there has been a rising interest in control of multiple vehicles for reasons such as increase in [...] Read more.

Control of autonomous vehicles for applications such as surveillance, search, and exploration has been a topic of great interest over the past two decades. In particular, there has been a rising interest in control of multiple vehicles for reasons such as increase in system reliability, robustness, and efficiency, with a possible reduction in cost. The exploration problem is NP hard even for a single vehicle/agent, and the use of multiple vehicles brings forth a whole new suite of problems associated with communication and cooperation between vehicles. The persistent surveillance problem differs from exploration since it involves continuous/repeated coverage of the target space, minimizing time between re-visits. The use of aerial vehicles demands consideration of vehicle dynamic and endurance constraints as well. Another aspect of the problem that has been investigated to a lesser extent is the design of the vehicles for particular missions. The intent of this paper is to thoroughly review the persistent surveillance problem, with particular focus on multiple Unmanned Air Vehicles (UAVs), and present some of our own work in this area. We investigate the different aspects of the problem and slightly digress into techniques that have been applied to exploration and coverage, but a comprehensive survey of all the work in multiple vehicle control for search, exploration, and coverage is beyond the scope of this paper. Full article

(This article belongs to the Special Issue Advances in Control Engineering)

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