Delay-Compound-Compensation Control for Photoelectric Tracking System Based on Improved Smith Predictor Scheme

Abstract

High control bandwidth is usually restricted in a photoelectric tracking system (PTS) based on a Charge-Couple Device(CCD) with time delay, which hinders a good tracking performance. Generally, a model-based delay-compensation controller called Smith predictor (SP) can help increase the controller gain to promote the bandwidth by separating delay from the control loop. However, the performance promotion is insufficient because the delay still stays in the forward channel which causes errors between output and input. And the increase of the controller gain is still limited due to the effect of model mismatch on stability. In this paper, to solve the problems, a delay-compound-compensation control (DCCC) based on improved SP by trajectory prediction and velocity feedforward is proposed. The additional trajectory prediction is used to further eliminate the effect of delay existing in the forward channel. The additional velocity feedforward is used to further reform the transfer characteristics limited by the controller gain. A Kalman filter-based design method of trajectory prediction is presented and the optimal design principle of feedback and feedforward controllers is given in the face of model mismatch. Experiments demonstrate that the DCCC is valid and could greatly promote the tracking performance in the low frequency.

The RSLQR Control Method Based on the Linear Extended State Observer in the Electro-Optical Tracking System

“…The electro-optical tracking platform is a kind of complex high-precision directional tracking system integrating light, machine and electricity. It is widely used in the fields of sea, land and air [1,2,3]. And it is mainly used for realtime accurate tracking and measurement of moving targets [4,5].…”

Line of Sight Tracking Method Based on Feedback Linearization and Command Planning

“…Furthermore, to reduce the harm of delay on the control system, a delay reparation method based on fractional feedback control was put forward in [11], which improved the closed-loop capability by using fractional-order phase and gain balance. Reference [13] proposed an improved Smith predictor delay composite compensation control based on trajectory prediction and velocity feedforward. The trajectory prediction can remove the delay existing in the forward channel, and the velocity feedforward can reduce controller gain limits.…”

Objective Prediction Tracking Control Technology Assisted by Inertial Information

“…The second category comprises commonly used methods for compensating delay characteristics, involving the application of Smith predictors and their enhanced versions [10][11][12]. For instance, Ren et al [10] applied the Smith predictor to the velocity loop of an electro-optical tracking system to compensate for the delay in the gyroscope measurement signal.…”

“…They estimated disturbance effects within the frequency band of interest based on a model-free approach and employed a method similar to the Smith predictor for disturbance feedforward compensation, thereby enhancing the disturbance rejection capabilities of optical components. Luo et al [12] combined the Smith predictor with velocity feedforward control to improve control system stability while providing feedforward compensation for delay. Despite the considerable benefits of these typical delay compensation methods based on the Smith predictor, they still exhibit some flaws.…”