Trajectory control of multi-link elastic robot manipulators via a nonlinear feedback controller and a robust servo controller

This paper investigates the control problem for multi-link elastic robot manipulators tracking desired trajectories with suppressed vibrations due to the elasticity of links. By using the virtual rigid link coordinate system, the finite-dimensional model is obtained. Then the controller is constructed by the nonlinear feedback controller and the robust servo controller. The nonlinear feedback controller compensating for the nonlinear terms contains not only rigid modes but also elastic modes estimated on the basis of the asymptotic perturbation techniques. The robust servo controller is designed for the low-dimensional model as it suppresses the elastic vibrations and eliminates the control and observation spillover. Some results of numerical simulations are presented to show the effectiveness of the design procedure proposed in this paper. In particular, it is shown that the proposed controller is robust against the model errors with the linearization, the modal truncation, and the parameter uncertainties.

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