Prediction Control Algorithm for Close-loop Adaptive Optical System

To reduce the effect of servo lag error in the close-loop adaptive optics system (AOS), a prediction control algorithm (PCA) is proposed in this paper. We describe a linear predictive controller that uses the historical voltages of deformable mirror to predict their future voltages in advance. The parameters of the predictor are optimized in real time by a modified Recursive Least-Square (RLS) algorithm. Numerical simulations are carried out to show the significant improvements brought by the predictor. The close-loop Strehl Ratio of the residual wave-front error and the power spectrum density of the residual voltages of deformable mirror are calculated as the evaluation criterions. The comparison results between the PCA and the classical proportional integral (PI) control algorithm show that the residual errors caused by servo lag in the system could be more effectively reduced by using the PCA than using the classical PI control algorithm. In addition, the control bandwidth of AOS is improved by using the PCA.