Robustness studies of a proximate time-optimal controller

Two practical time-optimal controllers for rapid slewing of type-three and type-two third-order plants, PTOS3 and PTOS3 tau , respectively, have been developed. The robustness of the PTOS3 tau and corresponding time-optimal controller is compared to parameter variations and flexible unmodeled dynamics. It is found that the PTOS3 tau controller is much more robust than the time-optimal controller. Simulation results show the increase in settling times of the PTOS3 tau and time-optimal controllers as the parameter tau of the type-two third-order plant, a/s/sup 2/( tau s+1), is varied from the nominal tau used in the controller designs. Simulation studies delineate the range of applicability of the PTOS3 tau when there are flexible unmodeled dynamics. A numerical method to calculate the time-optimal control of higher-order systems is presented and applied to the type-two third-order plant with flexible unmodeled dynamics. The results are compared with those of applying the PTOS3 tau to the same higher-order systems.<
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