A PRACTICALLY IMPLEMENTABLE DISCRETE TIME SLIDING MODE CONTROLLER FOR FLEXIBLE MANIPULATOR

S. Thomas and Mija S. J.

Keywords

Discrete sliding mode control, fast output sampling, flexible manipulator, tip position control

Abstract

Tip position controller designs for flexible manipulator using state variables (position, vibrating modes and their velocities) have been reported in the literature. But these methods need all states for feedback and hence have the associated difficulties in implementation as the vibratory modes will have to be measured or estimated. In a flexible one-link manipulator, the sensor and actuator are located at the two ends of the arm. They are thus noncollocated. Any sensor measurement at the tip will have with it some associated time delay in transferring it to the actuator. Hence from the practical view point of implementation one will have to think of discrete control. This paper proposes the application of fast output sampling feedback for control of tip position, which requires measurement of only the output (tip position) for synthesizing a discrete sliding mode controller. In this control method, the switching function and the control law are directly obtained from output samples. Thus the methodology adopted is simple and most suitable for practical implementation.

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