Dissertation > Industrial Technology > Automation technology,computer technology > Automation technology and equipment > Automation systems > Automatic control,automatic control system

Research on Friction Compensation in the Servo Systems

Author XuHongYang
Tutor WangYi
School Harbin Institute of Technology
Course Control Science and Engineering
Keywords servo system friction compensation LuGre friction model PID control
Type Master's thesis
Year 2012
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With the progress of science and technology, servo systems are becoming widelyused in many industries, such as aeronautic and astronautic industries and others. Andthe requirements for accuracy and performance of servo system are becoming more andmore rigid. However, the accuracy and performance of servo system is affected by thepresence of friction torque in the transmission, especially in the high-precision servosystems. Although it is necessary to eliminate the affect bought by friction torque, theprocessing is limited by economic and technique reason. Therefore, it is theorymeaningful and well application prospects to eliminate the affect bought by frictiontorque by the control method.In this article, the causes of friction are analyzed, and the mathematical modelsbased on friction theory are built, preparing for the following simulation and controlstrategy research. Meanwhile, the performance of servo motor is analyzed by themathematical models of friction, through the simulation plant to simulate the delay andother affect caused by friction.The control strategy for reducing the total harmonic distortion of the high-precisionangular vibration table is designed. At first, a transfer function of simplified controlsystem is built, and to eliminate the distortion the PID control strategy is introduced,and a well-performed control system is obtained.Given the parameters of an actual system, including the electric parameters andmechanical parameters will change when system working, which will affect theperformance of controllers. Therefore, an adaptive control method is used in the system.An adaptive control strategy is analyzed assuming the parameters of the system areknown, and the global asymptotic stability of the closed loop system are proved via aLyapunov-like argument.

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