Acquisition

trackingand pointing（ ATP） system is the core of high speed and large capacity of laser communication in atmosphere

spot jitter generated by the disturbances among long distance laser communication has seriously affects precise alignment between laser communication terminals

and greatly reduces the stability of communication link and quality. In order to suppress the facula dithering

improve precision of target tracking

an improved fast steering mirror（ FSM） control method is proposed. Features of self-adaptive control and conventional PID control are analyzed

and advantage of composite control with the two algorithms is discussed

reference model self-adaptive control algorithm of PID is proposed according to Lyapunov theory

and simulation analysis on the conventional PID and reference model self-adaptive and PID compound control algorithm is carried out and closedloop tracking experiment of actual facula dithering is conducted. Experimental results show that

overshoot adaptive PID controller obtained is 2 %

rising time is 3 ms

tracking precision is prior to 2 μrad

overall better than the conventional PID control algorithm. Compared with the traditional PID control

control algorithm which is proposed in this paper has better inhibition of spot jitter.