Nonlinear model based coordinated adaptive robust control of electro-hydraulic robotic arms via overparametrizing method

This paper studies the coordinated motion control of robotic manipulators driven by single-rod hydraulic actuators. We present a physical model based adaptive robust control (ARC) strategy to explicitly take into account the strong coupling among various hydraulic cylinders (or joints). The property that the adjoint matrix and determinant of the inertial matrix could be linearly parametrized by certain suitably selected parameters is fully exploited and the overparametrizing method is used. Furthermore, the proposed ARC controller guarantees a prescribed output tracking transient performance and final tracking accuracy while achieving asymptotic output tracking in the presence of parametric uncertainties only. Simulation and experimental results on a three degree-of-freedom hydraulic robot arm are presented to illustrate the proposed control algorithm.