Time-Optimal, Dual-Stage, Output Transition: With Pre/Post Actuation

This article considers the output transition problem, to change the output position, from an initial value to a final value, for dual-stage positioning systems. The main contribution of the article is to show that the use of preand post-actuation input (applied outside the transition interval without changing the output) can reduce the transition time beyond the standard bangbang-type inputs from the optimal state-transition approach. An example, motivated by diskdrives application, is used to illustrate the advantages of using (a) preand post-actuation and (b) the second actuator in dual-stage positioning system.