Page 665 - The Mechatronics Handbook

21

The Role of Controls

in Mechatronics

21.1 Introduction
21.2 Key Elements of Controlled
Mechatronic Systems
21.3 Integrated Modeling, Design
and Control Implementation
Modeling • Control System Design Methodologies
• Servo System Design • Design of a Mobile Robot
21.4 Modern Examples of Mechatronic
Systems in Action
Rudder Roll Stabilization of Ships • Compensation
of Nonlinear Effects in a Linear Motor
21.5 Special Requirements of Mechatronics
Job van Amerongen that Differentiate from “Classic”
University of Twente Systems and Control Design
21.1 Introduction

“Mechatronic design deals with the integrated and optimal design of a mechanical system and its
embedded control system.” This definition implies that the mechanical system is enhanced with electronic
components in order to achieve a better performance, a more flexible system, or just reduce the cost of
the system. In many cases the electronics are present in the form of a computer-based embedded (control)
system. This does not imply that every controlled mechanical system is a mechatronic system because
in many cases the control is just an add-on to the mechanical system in a sequential design procedure.
A real mechatronics approach requires that an optimal choice be made with respect to the realization of
the design specifications in the different domains. In control engineering the design of an optimal control
system is well understood and for linear systems standard methods exist. The optimization problem is
formulated as: given a process to be controlled, and given a performance index (cost function), find
optimal controller parameters such that the cost function is minimized. With a state feedback controller
and a quadratic cost function, solutions for the optimal controller gains can be found with standard
1
controller design software, such as Matlab (Fig. 21.1).
Mechatronic design on the contrary requires that not only the controller be optimized. It requires
optimization of the system as a whole. In the ideal case all the components in the system: the process
itself, the controller, as well as the sensors and actuators, should be optimized simultaneously (Fig. 21.2).
In general this is not feasible. The problem is ill defined and has to be split into smaller problems that
can be optimized separately. Later on the partial solutions have to be combined and the performance of
the complete system has to be evaluated. After eventually readjusting some parts of the system this leads
to a sub-optimal solution.

©2002 CRC Press LLC