Development of Servo-Controller to Compensate Friction Disturbances Automatically by Using Adaptive Control Technique

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To control servo systems in high performance of speed and accuracy, it is important to compensate unknown friction forces in the systems. In this project, several schemes to estimate and compensate the unknown friction forces are proposed.1. Since friction disturbances are periodic in rotating or repeatedly moving servo systems, it is necessary to estimate periodic disturbances for compensating the friction forces. An adaptive observer to estimate such disturbances is proposed. The observer includes a simple scheme to calculate the estimate of the disturbances.2. Two adaptive control schemes to compensate the friction forces are given. The first scheme compensates the forces by using estimated parameters and reduces control errors caused by estimation errors by disturbance decoupling method. In the second method, the unknown friction disturbances are compensated by a scheme of model reference adaptive control systems based on the two-parameter compensation schemes. These schemes are programmed for computer simulations.3. A sufficient condition for control systems to be stable is given. Applying this condition, it is shown that the systems compensating the friction disturbances are stable.4. Two experimental servo control systems are developed. These systems have interfaces to connect computers and they can be controlled by the connected computers. The first system is a servo motor connected with a computer. The second is a manipulator with 6 degrees of freedom, whose axes are controlled by computers. Using these systems, experiments to estimate the unknown friction disturbances are conducted.