Research On Control System Of Spacecraft Scanning Mechanism Driven By Ultrasonic Motor

The scanning mechanism,as an important part of the spacecraft(satellite)remote sensing load,drives the scanning mirror to realize the imaging of the target.With the continuous improvement of the load space resolution requirements,the requirements for the quality and rotation stability of the scanning mechanism have become higher and higher.Achieving high-precision scanning control has become one of the current research hotspots.Due to the large volume and weight of the scanning mechanism driven by traditional electromagnetic motors,this paper addresses the requirements of low speed,high torque and high control accuracy of a scanning mechanism,and constructs an ultrasonic motor driven scanning mechanism.Incremental PI algorithm.The designed scanning mechanism meets the goal of lighter than5 kg and less than 2% rotation stability.The main research contents and work of this article are as follows:1.Aiming at the problems of the existing scanning mechanism,an ultrasonic motor-driven scanning mechanism control system was designed.The prototype of the newly designed scanning mechanism reduced the weight by 87.2% compared with the existing scanning mechanism driven by the electromagnetic motor.2.Designed and implemented the controller with DSP + FPGA as the core.The controller adopts dual PWM structure circuit to realize the hierarchical control of output voltage amplitude and phase,and uses DDS technology to generate high-resolution PWM signals.The experimental results show that the controller has the advantages of high accuracy,wide dynamic adjustment range,flexible control mode,and easy expansion.3.In order to realize the high-precision and high-stability operation of the scanning mechanism,the speed-regulating mechanism,methods and characteristics of the ultrasonic motor are compared and analyzed,and the two-stage control of the drive circuit with dual PWM structure is introduced.Expert rules are designed for the existing incremental PID algorithm to set the control parameters,and an incremental PI algorithm for expert rule tuning is proposed.The experimental platform of the scanning mechanism control system was established,and the speed stability control experiment of the scanning mechanism was completed.The results show that the designed control algorithm can achieve a control effect with a rotation stability of less than 2%.