ROBUST TRACKING FOR UNCERTAIN FLEXIBLE STRUCTURES USING MIXED TIME-OPTIMAL AND SLIDING MODE CONTROL

摘要

An improvement step in robust control is studied foruncertain (linear or nonlinear) systems. The proposed two-stagecontrol scheme first modifies the original desiredtrajectory, and then imposes robustness against uncertainties intracking this modified trajectory. For the trajectorymodification stage, a simple scheme is considered : timeoptimal-rigid body motion (TO). The robustness stage isperformed using Sliding Mode Control with PerturbationEstimation (SMCPE), an advanced form of SMC. This routinebrings some strong features as demonstrated by examples. Arotating hub with flexible beam attachment is taken as the firstexample, and an undercontrolled two-mass system with alinear spring as the second. The comparative studies showsuperior results for the combination of TO-SMCPE over thebasic SMCPE. Moreover, this two-stage control exhibits stableand highly advantages performance even for cases where H ￥ -typeof robust control structure is declared unstable by earlierinvestigations.