Tracking Control of Constant-Linear-Velocity Spiral Reference by LQG Method

Abstract We report an extension of a recent LQG control method to track reference signals by which a constant-linear-velocity (CLV) spiral scan pattern is generated. In contrast to the constant-angular-velocity (CAV) spiral pattern, the instantaneous frequency of the CLV sinusoidal references considerably varies over the scan period. In addition, the reference amplitude is a nonlinear function of time, making the tracking of a CLV spiral reference a more challenging control objective. Considerable improvement in the tracking performance of the proposed time-varying controller is demonstrated through a reference scaling method. Experimental implementation on a MEMS nanopositioner further illustrates applicability of the proposed control approach.