Design And Research Of Ultrasonic Motor For Controlling Torque Gyro

The control torque gyro is a device that realizes the attitude control of the spacecraft through the gyro principle to realize the momentum exchange,and is widely used in various spacecraft such as artificial satellites and space stations.The control torque gyro is mainly composed of a high-speed component that generates angular momentum,a low-speed component that implements momentum exchange,and related control circuits.The low speed components of the existing control torque gyro generally consist of an electromagnetic motor and a reduction gear.The system has the disadvantages of complex structure,large volume,weak anti-electromagnetic interference capability,slow mechanical response,and difficulty in achieving high-precision control.Ultrasonic motor has the advantages of low speed,higher torque,self-locking of power failure,strong anti-electromagnetic interference capability,faster transient response and high positioning accuracy.In order to realize the attitude control of micro-satellite to complete the fast and accurate scanning and observation of the target area,this paper studies the ultrasonic motor used to drive the control moment gyro with the single-frame moment gyro in the background of the attitude control application of the micro-satellite.The main research contents and results of this paper are as follows:1.Based on the introduction of the working principle of single-frame torque gyro,the application status of the existing control torque gyro is analyzed.The existing electromagnetic motor drive control gyro can be analyzed for the extreme working environment of space.Driving the control torque gyro may be one of the ways to solve the problem.2.A single-frame torque gyro driven by traveling wave is designed.According to the mechanical structure of the control torque gyro,a hollow rotating traveling wave ultrasonic motor is designed.The stator size of the ultrasonic motor is optimized by the finite element method.The prototype was machined and tested.3.For the high vacuum demand of aerospace,a special-mode ultrasonic motor is proposed.The working mechanism of the special-mode ultrasonic motor is analyzed from the perspective of dynamics.The solving equations and nonlinear contact problems of the special-shaped linear motor are studied and analyzed.The modal analysis,modal identification,grid node trajectory calculation and load response calculation of the ultrasonic motor stator were carried out by using finite element software.Based on the stator structure size,the dynamics of the ultrasonic motor's operating frequency,modal aliasing and vibration amplitude were optimized.The prototype was made based on the optimization results.4.A three-dimensional model of the hetero-linear ultrasonic motor drive control torque gyro is designed.The modal analysis and stress distribution analysis of the momentum wheel offset of the momentum wheel are completed by the finite element method.The strength of the momentum wheel bearing was checked.The prototype was finally processed according to the optimization and calibration results.5.According to the system requirements,relevant experimental verification and partial parameter optimization were carried out on the designed prototype.The experimental results show that the optimized load performance and speed performance of the special-shaped ultrasonic motor are greatly improved.The coupling experiment between ultrasonic motor and control torque gyro shows that the rotational speed of the momentum wheel has a great influence on the rotational speed of the frame at low speed;when the rotational speed of the momentum wheel increases,the rotational speed of the momentum wheel has little effect on the rotational speed of the frame.