Act and Wait Concept in Force Controlled Systems With Discrete Delayed Feedback

Abstract

A 1 DOF model of force control is considered with discrete delayed feedback. The act and wait control concept is introduced as a special case of periodic control: the feedback gain is constant for a sampling period (act), then it is zero for a certain number of periods (wait), then it is constant again, etc. It is shown that by applying the act and wait concept, the stability properties of the system improve and the force error caused by the Coulomb friction decreases. If the period of gain variation is larger than the feedback delay, then the system performance changes radically: the stability properties improve significantly, and the optimal control parameters can provide dead beat control. This way, by using the act and wait concept, the delay effects are eliminated from the system.

Inverting Control, a New Strategy on Time Delayed Systems

“…From the stability analysis angle, earlier investigations provided enormous insight. There is however, very limited control synthesis studies in the literature on time delayed systems, again mainly due to the notoriety of the problem (Niculescu 2001;Filipovic and Olgac 2002;Insperger and Stépán 2005). Author's group has contributed in this field, both from the stability analysis and the control synthesis aspects of the research (Olgac and Sipahi 2002;Olgac, Ergenc and Sipahi 2005;Sipahi and Olgac 2005;Olgac and Sipahi 2006; * Author was affiliated with University of Connecticut when the work was done.…”