UBC Theses and Dissertations

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UBC Theses and Dissertations

Robotic manipulator modelling and control Shi, Pingnan


In this thesis, a special control strategy is proposed which treats manipulators as a unique class of systems with their own unique characteristics. The objectives of proposing the control strategy are to obtain 1) no or tolerable overshoot; 2) smaller settling time; and 3) higher accuracy. Two two-link manipulators and one three-link manipulator were simulated and controlled by the proposed control strategy. The results are provided in the thesis. The proposed control strategy has the structure of local and global control. The local control takes care of the links. Its objective is to drive the links to the desired positions, disregarding the effects caused by gravity torques and the coupling and the interaction between links. The objective of the global control is to compensate for the effects ignored by the local control. The local control law has the feature of variable structure control. The decision concerning the control to be switched to depends on the region in the phase-plane the trajectory of the subsystem (link) is in. The switching time is determined by the state of the subsystem in the phase-plane via a simple criterion. A simplified model is also proposed and used to construct the control strategy. The model is built up with emphasis on the effective moment of inertia and gravity torques.

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