Optimal Preview Control of a Dual-Stage Actuator System for Triangular Reference Tracking

This brief proposes an optimal preview control law for a dual-stage actuator (DSA) system to track triangular reference, which is essential in many raster scan motion control applications. The main difficulty of tracking triangular reference is to follow the waveform fast and accurately when its slope switches. For this goal, we first discuss a time-optimal controller (TOC) for the primary stage, which is a double integrator system. The TOC is then proved to achieve the minimum overshoot. This result is a new contribution to DSA control applications because it leads to a reference profile of minimum amplitude for the secondary stage to follow and thus significantly prevents the saturation of the secondary actuator. Subsequently, we propose an optimal preview control with the use of the information of the future reference to further reduce the settling time and overshoot. Finally, the secondary actuator controller is also given. Experimental results are shown to verify the effectiveness of the proposed control design.