Closed-loop Identification for Control of Linear Parameter Varying Systems

This paper deals with system identification for control of linear parametervarying systems. In practical applications, it is often important to be ableto identify small plant changes in an incremental manner without shuttingdown the system and/or disconnecting the controller; unfortunately, closed-loop system identification is more difficult than open-loop identification. Inthis paper we prove that the so-called Hansen Scheme, a technique knownfrom linear time-invariant systems theory for transforming closed-loop systemidentification problems into open-loop-like problems, can be extended toaccommodate linear parameter varying systems as well. We investigate theidentified subsystem’s parameter dependency and observe that, under mildassumptions, the identified subsystem is affine in the parameter vector. Various identification methods are compared in direct and Hansen Scheme setups in simulation studies, and the application of the Hansen Scheme is seen to improve the identification performance