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Hybrid position-force control of climbing parallel robot using electrohydraulic servo actuators

Abstract:

An Hybrid Position-Force control scheme for hydraulic actuators is proposed for a Climbing Parallel Robot (CPR) based on a Stewart-Gough mechanism. The hydraulics actuators are modeled, and expressed as state-space variables. The parameter identification is based on experimental data and the box-grey identification procedure, using a minimization pbkp_rediction error criterion. A cascade control strategy with feedback linearization and state estimation based on two control loops is used for each hydraulic actuator. The control strategy proposed for the hydraulic actuator is implemented in a real prototype, considering a position tracking task. The model of the actuators are included in the dynamic model of the CPR obtained via the virtual work formulation, which considers the thirteen bodies that composes the Stewart-Gough robot. The proposed controller is simulated and implemented on the CPR to test the limits of its performance and the real effects of friction. The results obtained from simulation and experiments are presented and discussed. Copyright © 2011 by ASME.