Research On Coarse Tracking Mirror Control System Based On Planetary Gear

In the space optical communication system,acquisition,tracking,pointing(ATP for short)techniques are usually used to achieve precise alignment between two parties in order to establish a good communication link and maintain the link.The coarse tracking technology is an indispensable part of the ATP technology,and it is an important subsystem for implementing the ATP function.The traditional coarse tracking equipment is bulky and consumes high power.However,with the development of science and technology,especially the development of cutting-edge technologies,the application of coarse tracking has also been developed from a static platform to a moving platform such as a car,an airborne,a spaceborne,etc.It is required that the coarse tracking device be developed towards the trend of miniaturization and intelligence,and the device must have high tracking accuracy and low power consumption.Planetary gears have the advantages of low power consumption,small size,etc.Therefore,this paper mainly studies the two-dimensional tracking mirror control system based on planetary gear transmission with the background of space optical communication.This paper first outlines the development of planetary gear control system at home and abroad,analyzes the main factors that affect the accuracy of planetary gear-driven coarse tracking mirror: friction disturbance and gear gap of planetary gear.The effects of these two disturbances on the coarse tracking control are analyzed.The motor,planetary gear and tracking mirror in the planetary gear drive coarse tracking mirror control system are respectively modeled to provide a theoretical basis for the design of the control system.On the basis of consulting a large number of documents and related theories,this paper analyzes and compares the existing friction in the system and the backlash problem existing in the planetary gear,introduces several commonly used models of friction and backlash,and illustrates the current domestic and international friction and Gaps often usesome of thecompensation control methods.In order to accomplish the high precision tracking of the coarse tracking mirror driven by a planetary gear and to suppress some nonlinear deadzone characteristics such as the friction disturbance and the backlash of the planetary gear in the coarse tracking system,a non-dependent model based on multi-sensor fusion control(DOB)control method.The method uses the motor side encoder to measure the motor speed and the load speed measured by the encoder at the load speed measurement component,and then utilizes the measured speed deviation To implement this DOB interference.Through the simulation analysis of the planetary gear transmission model,it is confirmed that the model-independent DOB control method of multi-sensor fusion control has a good inhibitory effect on the existence of dead-zone characteristics in the system,enabling the system to achieve high-precision tracking.The mechanical design of the coarse tracking mirror,the selection of the motor,the planetary gears and the encoder are described.Finally,an experimental platform for the planetary gear driving coarse tracking mirror is established,and a model-independent disturbance observer control method for multi-sensor fusion control is performed.The experimental verification shows that this method can realize the suppression of the nonlinear disturbance in the planetary gear transmission system and realize the high-precision tracking of the system.