Driving control for mounting rack of slant axis astronomical telescopes

The non-vertical structure in traditional mounting rack of a slant axis astronomical telescope may cause an image field rotation, which will effect the pointing and tracking of the telescope. There fore, a mounting rack with a slant axis of 45° is developed. By selecting the sun as the tracking target, a hardware driving control system for the mounting rack is designed. Capturing the target by a camera in real time, the system uses Digital Signal Processors (DSPs) here for analyzing exactly the centroid position of target image and decouples the deviation between the two directions by image despun scheme. Combined the fuzzy control and neural network, a self-adaptive fuzzy PID approach with a single neuron is proposed for regulating the position errors of the slant and azimuth respectively to achieve tracking and positioning. The experimental results show that the horizontal and slant axis azimuth tracking bias errors are within 2 pixels, and the average tracking error is 0.123 2° for the horizontal orientation and 0.155° for the vertical direction respectively. Experimental results indicate that the driving system is very robust. It solves the control problem caused by image rotations and can meet the precision requirement. ©, 2015, Chinese Academy of Sciences. All right reserved.