Control of Mechatronic Systems
2: Center for Automotive Research, Department of Mechanical and Aerospace Engineering, Ohio State University, Columbus, OH, USA
3: Dept. of Automatic Control (EIM-E), Paderborn University, Paderborn, Germany
4: Department of Mechanical Engineering, Istanbul Okan University, Istanbul, Turkey
This book introduces researchers and advanced students with a basic control systems background to an array of control techniques which they can easily implement and use to meet the required performance specifications for their mechatronic applications. It is the result of close to two decades of work of the authors on modeling, simulating and controlling different mechatronic systems from the motion control, automotive control and micro and nano-mechanical systems control areas. The methods presented in the book have all been tested by the authors and a very large group of researchers, who have produced practically implementable controllers with highly successful results. The approach that is recommended in this book is to first start with a conventional control method which may then be cascaded with a feedforward controller if the input is known or can be measured with a preview; to add a disturbance observer if unknown disturbances are to be rejected and if regulation of the uncertain plant about a nominal model is desired; and to add a repetitive controller to take care of any periodic inputs of fixed and known period. Case studies ranging from road vehicle yaw stability control and automated path following, to decoupling control of piezotube actuators in an atomic force microscope are presented. Parameter space based methods are used in the book for achieving robust controllers. Control of Mechatronic Systems is essential reading for researchers and advanced students who want to be exposed to control methods that have been field tested in a wide variety of mechatronic applications, and for practicing engineers who design and implement feedback control systems.
Inspec keywords: control system synthesis; feedback; robust control; mechatronics
Other keywords: robust controller design; feedback control systems; mechatronic systems
Subjects: Control technology and theory (production); General and management topics; General topics in manufacturing and production engineering; Micromechanics (mechanical engineering); Stability in control theory; Control system analysis and synthesis methods; Mechatronics industry
- Book DOI: 10.1049/PBCE104E
- Chapter DOI: 10.1049/PBCE104E
- ISBN: 9781785611445
- e-ISBN: 9781785611452
- Page count: 250
- Format: PDF
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Front Matter
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1 Introduction
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We begin the article with an introduction to mechatronic systems, the need for controlling them and the control methods that will be presented in this book for this purpose. Today's engineers face truly mechatronic plants and real control design challenges. They are required to do multi-domain modelling and use well-established control methods that have been successfully applied earlier for controlling mechatronic systems. This book concentrates on several of these control methods that have been successfully applied to real-world problems and are embedded in a lot of the products that we use in our everyday life.
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2 Parameter space based robust control methods
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The parameter space approach to robust control is presented in this paper as a pre-requisite to the remaining book chapters. The well-established method of mapping the left-half plane for Hurwitz stability or a smaller bounded subregion of the left-half plane for D-stability are presented first. Mapping of phase and gain margin bounds and different sensitivity bounds to parameter space are introduced later in the paper with illustrative examples.
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3 Classical control
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Conventional control methods, frequently used in the industry, including PID controllers, phase lead and lag compensators, and their variations are treated in this chapter. These are the first control methods that should be applied to a new problem, and if they solve the control design specifications satisfactorily, there is no need to try more advanced control methods or alternative control architectures like two degrees-of-freedom control, for example. These classical techniques that work with Single-Input-Single-Output (SISO) transfer functions and root locus or frequency domain design methods are called conventional (or traditional) control systems here for lack of better terminology. We refrain from the use of classical control systems as techniques like state variable feedback and LQR that used to be known as modern control, and techniques like ℋ∞ control and μ-synthesis that used to be called new approaches. These have now become classical approaches themselves as decades have passed since their introduction to the controls literature. Conventional control techniques work best for SISO, Linear-Time-Invariant (LTI) systems where the required performance specifications are given in the time-domain and/or frequency-domain. Despite the presence of a vast number of advanced control techniques in the literature, conventional control methods are widely used in the control of mechatronic systems because they can easily be implemented as real-time systems and their costs are relatively cheaper as compared to more advanced techniques. In this paper, conventional control methods such as lead, lag, lead-lag compensators, PI, PD and PID controllers are reviewed first. This is followed by analytical solution techniques for their design based on desired phase margin, gain crossover frequency, and error constant combination. The use of existing numerical optimisation based PID and controller parameter tuners in MATLAB® and Simulink® is presented next. The paper ends with the application of the multi-objective parameter space design method of Chapter 2 to PID controller design as a case study. All three of the proportional, integral and derivative gains are plotted in a three-dimensional parameter space in this case study.
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4 Input shaping control
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This chapter is on input shaping, also known as preview control. This is a feedforward control approach that can be applied to reference and disturbance inputs that are known in advance. A discrete-time closed-loop controlled system is considered and its approximate inverse filter that is not causal is designed to achieve desirable inputto-output behaviour. The external input is assumed to be known in advance. Thus, the approximate inverse filter also known as the preview filter as it is not causal. It is applied to the known input offline, resulting in a new input which is applied online to the closed-loop system (hence the name input shaping). This chapter starts with a characterisation of non-minimum phase zeros and approximate inversion methods used to treat them as they cannot be inverted directly. The ZP, ZPG, ZPGE and ZPGO and TSA methods are presented in this chapter as different possible approximate inverse filters for feedforward control.
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5 Disturbance observer control
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The book reviews developments in the following fields: disturbance observer control; continuous-time disturbance observer; SISO disturbance observer; discrete-time disturbance observer; MIMO disturbance observer; and communication disturbance observer.
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6 Repetitive control
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Repetitive control uses a time delay element in a feedback loop to reduce tracking error for systems with periodic reference or disturbance inputs of known period. The SISO continuous-time and discrete-time repetitive control architectures and design methods based on minimising mixed sensitivity at the fundamental periodic frequency and its harmonics are introduced in this chapter. The chapter also has COMES toolbox design examples. The first example is on an AFM application while the second example is on a Quanser QUBE™ servo system application.
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7 Summary and conclusions
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Several different methods that have been successfully applied in the past for controlling mechatronic systems are presented in this book. In this final chapter of the book, the main findings are first summarised and then followed by conclusions.
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Rapid control prototyping and hardware-in-the-loop simulation
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Hardware-in-the-loop simulation and rapid controller prototyping are two techniques that are used frequently in the V-cycle design process of control systems for mechatronic products and are, thus, briefly reviewed in the article.
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Back Matter
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