Bilateral feedback control of telemanipulators via computer network

Providing force information do a human operator improves the reality of teleoperation. When the communication block between a master and a slave has a transmission time delay, the bilateral feedback system is easily destabilized. Anderson and Spong (1989) guaranteed passivity in the communication block by using scattering transformation and overcame this instability caused by the time delay. This method can be applied to the communication block with constant time delay. Different from traditional teleoperation systems, the transmission time delay irregularly changes in a computer network. This paper reveals that the variable time delay destabilizes bilateral master slave manipulator with scattering transformation and proposes the virtual time delay method, that keeps the apparent time delay constant. This new compensation method has been implemented in a single axis master slave manipulator system connected to a computer network and experimental results illustrate the validity of the proposed method.