Impedance control of a teleoperated mini excavator

A position-based impedance controller for excavator-type manipulators has been developed in our laboratory. This paper describes the proposed impedance controller and presents supporting experimental results. First, the problem of impedance control for a single hydraulic actuator is addressed and a method is presented for stability analysis. Steady-state position and force tracking of the closed loop system is also studied. Then, the desired impedance of the end-effector (bucket of the excavator) is mapped onto the hydraulic cylinders using the arm Jacobian and accurate estimates of the arm inertial and gravity terms. A nonconservative method is presented for predicting stability of the multivariable closed loop system. Experiments with an instrumented mini excavator (for the single cylinder case) show that the designed impedance controller has a good performance.