Research On The Scanning System Of High Control Precision

With the improving requirement of space remote sensing detection, the performance index of the load demand to high resolution and wide field of view. Currently an electrical scanning with mechanical is commonly used on the field of remote sensing detection, the requirements of high spatial resolution of scanning control index requirements are getting higher and higher, especially for scanning mirror pointing movement control precision demand has reached arcsecond level. How to realize the scanning system of high control precision, the research and design of the project is the difficulty problem currently.The control high precision scanning system has the position stability and speed stability requirements. The position stability requires the scanning mirror to the point at the specified position, and the fluctuation of the position can not be exceeded ?1?rad(1?). The velocity stability requires the wave amplitude of the scanning mirror below 1% when move at a speed of 5 / s.In order to achieve the high accuracy of the index requirements, current loop, speed loop and position loop were adopted in this paper as the servo control system. On the basis of the full investigation, the permanent magnet synchronous motor(PMSM) was chosed as the motor, SVPWM and 0di ? vector control mode were used in order to reduce the torque fluctuation. The paper used MATLAB and Simulink to build the mathematical module of the servo control system. Through the scanning and the pointing control experiments, the simulation results show that the high precision control target can be achieved from the theory.According to the requirement of the index and the theory analysis, the accuracy of the feedback sensor was the key factor to achieve the high precision pointing control. In this paper, we selected the small resistance sampling as the current sensor, and the high precision of the inductosyn of 720 poles as the axis angle sensor and speed sensor. In order to realize the absolute angle measurement, the encoder and the inductosyn were used as the rough/fine channel for the first time, and the data fusion was used to obtain the high precision absolute shaft angle position information.Then, in order to resist the noise, the control algorithm based on the model reference adaptive control method was achieved in the position loop, compared with the PID control algorithm it can significantly reduce the control deviation. According to the fluctuation of the velocity in the actual system, generated by the motor equaled the load consumption, the refinement motion equation of the system was obtained, while using the system identification method friction torque model had been identfied. The mathematical model of servo control system with friction disturbance and torque ripple was established. For periodic fluctuation in the speed loop, through the comparison of simulation model and reality judgment it was caused by cogging torque. The mathematical model of the cogging torque was analyzed, and instruction current injected into the compensation method was proposed, the simulation and practical control results showed that it significantly reduced the system effects of the cogging torque.Because of the actual demand of the system, the hardware in loop simulation platform of HiGale was used to simulate the scanning system. Final pointing control system reached an accuracy of 0.27?rad(1?).