Bilateral control of teleoperators with time delay

A control law for teleoperators is presented which overcomes the instability caused by time delay. By using passivity and scattering theory, a criterion is developed which shows why existing bilateral control systems are unstable for certain environments, and why the proposed bilateral control law is stable for any environment and any time delay. The control law has been implemented on a single-axis force-reflecting hand controller, and preliminary results are shown. To keep the presentation clear, a single-degree-of-freedom (DOF) linear time-invariant (LTI) teleoperator system is discussed. Nevertheless, results can be extended, without loss of generality, to an n-DOF nonlinear teleoperation system