Performance Research Of Target Acquisition For Photoelectrical Theodolite Based On Sliding Mode Control

The target acquisition of photoelectric theodolite system refers to the transient process in responding the position signal of target found in the view field, and acquisition capability depends on dynamic performance of the system.In this paper, sliding mode control (SMC) is proposed for servo system of photoelectric theodolite and target acquisition capability and performance are both improved. Besides, sliding surface with variable coefficient and continuous control law without switching is introduced in the SMC controller design. The improved SMC controller has eliminated system's chattering phenomenon and full-field acquisition with rapid response and non-overshoot is achieved.In simulation, the width of view field is 1.53o, the max angular velocity of theodolite is 78 o/s, and target extraction time is 3 frames. Under these conditions, the system can acquire targets with a max velocity of 12.5 o/s not using memory tracking, while can acquire targets with a max velocity of 23 o/s using memory tracking, when the settling time is limited in 0.8s.In addition, TV tracker usually causes input delay of miss distance, because the sampling frequency is too low and the image processing delays for some time. This paper proposes a method of miss distance prediction based on adaptive LMS filter and successfully overcomes the adverse effects owing to the input delay of miss distance.