Saturated Prescribed Space-Time Adaptive Sliding Mode Control With its Implementation on Piezo-Actuated Fast Steering Mirror.

This paper presents the design and testing of a novel saturated prescribed space-time adaptive sliding mode control (SPSASMC) strategy dedicated to the disturbed system with input saturation. In comparison with traditional adaptive sliding mode controllers, the reported scheme guarantees the prescribed space-time convergence. Namely, the sliding variable is ensured to converge to a prescribed space within a prescribed time. Moreover, the convergence accuracy and time are capable of being picked in advance, which are not affected by initial condition, lumped disturbance, and input saturation. Besides, the SPSASMC scheme can automatically adjust the control gain according to the lumped disturbance, alleviating overestimation problem. Mean-while, the reported scheme also avoids the segmentation of the control scheme. The stability is verified in theory, and the performance improvement is validated by simulations and experimental studies in a piezo-actuated fast steering mirror.