Collocated versus Non-collocated Control

Introduction

In the foregoing chapters, we have seen that the use of collocated actuator and sensor pairs, for a lightly damped flexible structure, always leads to alternating poles and zeros near the imaginary axis, Fig.6.1.a. In this chapter, using the root locus technique, we show that this property guarantees the asymptotic stability of a wide class of single-input single-output (SISO) control systems, even if the system parameters are subject to large perturbations. This is because the root locus plot keeps the same general shape, and remains entirely within the left half plane when the system parameters are changed from their nominal values. Such a control system is said to be robust with respect to stability. The use of collocated actuator/sensor pairs is recommended whenever it is possible.

An Erratum for this chapter can be found at http://dx.doi.org/10.1007/978-94-007-2033-6_18