1st Edition

DC Servos Application and Design with MATLAB®

By Stephen M. Tobin Copyright 2010
    220 Pages 126 B/W Illustrations
    by CRC Press

    220 Pages 126 B/W Illustrations
    by CRC Press

    Fundamental to the control of mechatronic devices, the servomechanism applies feedback from the device in question to regulate its position, velocity, or some other physical attribute. Successful mastery of servo control requires an understanding of a wide range of engineering disciplines, making it difficult and time-consuming to master it all—and even harder to find an all-encompassing guide that shows you how.

    DC Servos: Application and Design with MATLAB® is designed and written with this problem in mind. It breaks down the practical knowledge required from the various branches of applied science—electrical and mechanical engineering, analog electronics, mechanics, control theory, digital electronics, embedded computing, and firmware design—into a cohesive and usable framework. Today, DC servos are working around the world in countless applications—CD players, ink-jet printers, robots, machining centers, vending machines, eyeglass manufacturing machines, home appliances, and automotive seat positioners, just to name a few.

    This book balances coverage of theoretical and practical aspects of application and design of DC servomechanisms. It also provides detailed coverage of feedback transducers, particularly the application of optical encoders to real systems. It covers how to use the MATLAB® Control System Toolbox specifically for servo design, to make the design process faster and more interactive. It also presents two complete, bench-tested reference designs that can be duplicated using readily available parts, so you can build your own servo and see it in action.

    Author Stephen M. Tobin is an expert in motion control and electro-optical instrumentation and a respected consultant in the medical device and manufacturing automation communities. In order to instill confidence in the engineers, scientists, students, and hobbyists designing the ever more complex machines of the 21st century, Tobin guides the reader on a short journey through "servo school," imparting his lifelong passion for motion control along the way.

    DC Servo Systems Defined
    Scope and Definition
    The Concept of Feedback Control
    Types of Control
    Comments on Motion Control
    Introduction to a DC Motor Driving a Mechanical Load
    Realization of a Velocity Servo

    Anatomy of a Continuous-Time DC Servo
    Description
    Intended Use
    The Prototype
    Electrical Design and Construction
    Mechanical Design and Construction
    Parts List
    The Prototype as a Control System
    Block Diagram Representations
    Electrical Schematic Walk-Through

    DC Motors in Servo Systems
    Operational Principles
    Basic Classes of DC Motors
    Considerations in Motor Selection
    Procedure for Meeting a Design Goal
    Mathematical Modeling of DC Motors and Transmissions
    Direct-Drive Model
    Motor and Gear Train Model

    Feedback Control Systems
    Mathematical Notation
    Linear, Time-Invariant Systems
    Oscillations, Rotating Vectors, and the Complex Plane
    From Fourier series to Laplace Transform
    Elementary Laplace Transforms
    System Analysis Using Laplace Transforms
    Philosophy of Feedback Control
    Accuracy of Feedback Systems
    Stability Assessment—the Root-Locus Method

    Proportional Control of a Second-Order DC Servo
    Proportional Control
    Second-Order Approximation
    Basic Approach
    Transfer Function Development
    Response to a Step-Input Command
    Response to a Ramp-Input Command
    Response to a Sinusoidal-Input Command

    Compensation of a Continuous-Time DC Servo
    Compensation Using Derivative Control
    Compensation Using Integral Control
    Compensation Using Derivative and Integral Control
    Tools for Predicting Performance
    Overall Compensation Strategy
    Op-Amps and Control Systems
    Compensation by Theoretical Prediction

    DC Servo Amplifiers and Shaft Encoders
    DC Servo Amplifiers
    PWM Switch-Mode Amplifiers
    Sign/Magnitude Control with the LMD18200
    Voltage Source versus Current Source
    Shaft Encoders

    Control of a Position Servo Using a PIC Microcontroller
    Initial Motor Selection
    Setting the Move Requirements
    Hardware and Software Development

    Appendix

     

    Biography

    Stephen M. Tobin is the founder and president of Optical Tools Corporation. He received his B.S. degree in Mechanical Engineering from the University of New Hampshire in 1983. He spent the first five years of his career in the motion control field, working in step motor and optical encoder design engineering with divisions of Allied-Signal and Dresser Industries. He then turned his attention to the development of electro-optical instrumentation. He joined General Eastern Instruments (now a division of General Electric) in 1988, working on closed-loop optical humidity measurement systems. While employed at General Eastern, he earned his M.S. degree in electrical engineering with a concentration in electro-optics from Tufts University in 1994. He later spent six years developing medical devices at Arthur D. Little, a world-renowned consulting firm based in Cambridge, Massachusetts. Motion control continues to be a lifelong passion for Mr. Tobin, who founded Optical Tools Corporation in 2004 and continues to consult for the medical device and manufacturing automation communities. He holds four U.S. patents and is a member of the Tau Beta Pi National Engineering Honor Society.