Accurate and Efficient Positioning of Ground Based Telescope Using Tracking Differentiator with an Adaptive Parameter

An accurate and efficient positioning method for the ground based telescope has been proposed in this paper. As the inner control loop, the speed loop can reject the total disturbance timely using a 2nd order extended state observer (ESO). Then the position loop can be easily approximated to be an I type system using the proportional controller. In order to mediate the contradiction between the speediness and overshoot in the position loop, a tracking differentiator with an adaptive parameter (ATD) has been proposed to give the transitional process for the position loop and the speed feed forward information for the speed control loop. Compared with the existing methods, the proposed ATD can easily provide a smooth position transitional process with the speed and acceleration limits which is more consistent with the response ability of the physical system. It is concluded that the proposed control algorithm displays a well control performance in a large range of position step responses of the telescope.