Design of a dynamic pattern generator based on the linear motion system

Abstract

The dynamic pattern generator of resolution test target is widely used to evaluate the imaging quality of the optical system. The dynamic pattern generator is composed of resolution test target and linear motion device and it can provide uniform motion within 400 millimeters. The resolution test target is photoengraved on the demands of photoelectric detection system and their patterns are different to be replaced. The length of the resolution test targets are specially designed to reduce the difficulty of the time system synchronism. The linear motion device is made of linear motor servo system. It can implement high speed, high precision and reliable motion. The servo system is designed with current loop, speed loop and position loop. The current loop and the speed loop are the inner control loops of the servo system and they can compensate the influence of the power fluctuation and nonlinear, uncertain factors to lessen the burden of the main loop. The inner loop employs proportion and integration (PI) algorithm without derivation feedback. The position loop, which belongs to the outer control loop, adopts proportion, integration and derivation (PID) algorithm and forward feedback algorithm. The Hall sensors are feedbacks of the current loop, the grating rule is the feedback for both the speed loop and position loop. The servo system is designed for the speed stability, so the speed is the control goal. Especially, control of high speed and low speed is implemented by speed and acceleration forward feedback. The servo system can get the precision of 1%.