Nonlinear Disturbance Observer Based Impedance Control for a Teleoperation System Under Time Delay

In this paper a nonlinear disturbance observer (NDO) based impedance control is proposed for a teleoperation system. The unknown friction and uncertainties will be estimated by the observer and added to the control input for compensation. Although friction will improve the stability, it worsens the transparency of the system which is another major point in teleoperation systems. The stability of the system is guaranteed by Lyapunov stability criterion and selecting the best design parameters. Tracking of force/position is achieved by these parameters. Also a fixed time delay is added to the system because of delays in the cables and other sources, it is then compensated with the designed controller. Performance of the proposed control is validated by experimental results.