9. Recursive Plant Model Identification in Closed Loop

Iterative combination of identification in closed loop and robust control redesign leads to a two time scale adaptive control system very appealing in practice. The chapter is dedicated to the presentation of recursive algorithms for plant identification in closed-loop operation and their application. Two classes of algorithms will be presented, analyzed and evaluated experimentally: closed-loop output error algorithms and filtered open-loop recursive identification algorithms. Specific techniques for model validation in the context of identification in closed loop will also be presented. The performance of the various algorithms will be illustrated by simulation and by their application to the identification in closed loop and controller re-design of a flexible transmission control system.