Study on the Low Velocity Properties and Jitter Compensation for the Servo System
|School||Changchun Institute of Optics and Fine Mechanics and Physics Institute|
|Keywords||Low speed jitter friction model motor torque wave adaptive repeat control|
Chen Juan (Optic Engineering ) Directed by Chen TaoThe optoelectronic tracking technology takes a key role in the area of aviation and navigation. As a hardware.the gimble servosystem design is very important in the making of the optoelectronic tracking system. The precision of the position.speed and the speed stability are the key indexes. For the optic measurement system in the high space.the minimum stable speed and high precision are needed. So.the low speed jitter problem has been the central task in the servo system research. The improvement of the working precision at low speed is hindered by the disturbances of the friction moment and the motor torque wave,while the decrease of the disturbances is restricted by the making technology. For the reason, the research of the low speed properties and corresponding compensation methods means a lot for the optoelectronic tracking system.Taking the 718 model gimble as an object, the paper focuses on the influences of the nonlinear friction moment and the motor torque wave to the system’precision at low speed first, then, makes the theoretical analysis and simulation. The experimental verification is carried out in the 718 model for the effectiveness and feasibility of the discussed compensation methods.The low speed properties and the main reasons for the jitter are analysed. The measurement of the friction moment and motor torque wave verifies that the Stribeck friction model is accurate and the wave is periodic. The minimun stable speed is given when the disturbances of the friction and the wave are considered. Consequently, the compensation methods are worked out.Basing on the Coulomb friction model, a Model Reference Adaptive Control System is designed first according to Lyarpnov stable theory. Considering the real situation at low speed region, the Stribeck model controller is put into use also. The both regulators are studied through simulation.inIf the parameters of the friction model are unknown or unprecised, and the motor torque wave is periodic, the repeat-study control technique is used. We discuss the stable condition when introducing the technique into the system, and have a low-pass filter to ease the stable condition. The sine is used in the simulation.Being aimed at the compensation methods of both the adaptive control basing on the friction model and the repeat control regulator, some experiments are carred out to verify the effectiveness and feasibility of the compensation. The signals which are introduced into the system are ramp and sine for testing the minimum stable speed and error.