Research On High Precision Control Of Torque Motor For Laser Communication Platform

Laser communication uses laser as a carrier for information transmission.It has great potential due to its advantages of large amount of communication information,low power consumption,good confidentiality,small size and light weight of communication terminal.In order to achieve the stable establishment of the communication link between the two ends of the laser communication,high-accuracy acquisition pointing tracking subsystem(APT)is the first problem to be solved.The high-precision motor drive system is the basis for the high-precision APT technology,and it is also the prerequisite and guarantee for laser communication.This thesis takes the permanent magnet torque motor drive system applied to the laser communication platform as the research object,and studies and analyzes the problems of speed ripple suppression,improved anti-disturbance ability and position tracking ability,and improved position detection accuracy.First,the thesis gives the mathematical model of the permanent magnet torque motor and its vector control block diagram.On this basis,the cogging torque,electromagnetic torque ripple,friction torque,dead zone effect,current sampling error are analyzed.The effect of delay on the current,speed and position control performance of the system.It lays a theoretical foundation for the follow-up control strategy research.In order to solve the problem of insufficient accuracy of the position sensor when the system is running at low speed,on the basis of using the sinusoidal encoder as the position sensor,a subdivision method based on highly linearization is proposed to effectively avoid the amplitude deviation on the subdivision accuracy.The effect of improving the position detection accuracy makes the sinusoidal encoder with insufficient resolution able to meet the position detection accuracy of the high-precision control system.In view of the speed ripple caused by sudden load in nonlinear factors,an antidisturbance control strategy based on sliding mode control is proposed,and a new approach law is adopted to improve the contradiction between approach speed and system chattering degree in the traditional approach law.Considering the disturbance of the load torque of the system,when the disturbance is too large,the chattering phenomenon of the system may be aggravated.In view of this situation,a sliding mode disturbance observer based on a new approach law is proposed to further improve the anti-disturbance performance of the system.Aiming at the problem that the friction torque has a great influence on the position control accuracy of the permanent magnet torque motor drive system,the disturbance observer cannot obtain accurate friction torque at extremely low speeds,and a friction compensation control based on the Lu Gre friction model is proposed.Considering the accuracy of Lu Gre friction model identification and mechanical wear,it will cause the actual friction torque to be inconsistent with the friction model.An adaptive friction compensation control based on the Lu Gre model is proposed to further suppress the friction torque and improve the system position control accuracy.