Switching Time Domain Passivity Control for Multilateral Teleoperation Systems Under Time Varying Delays

Time domain passivity control, a well known control scheme widely used for teleoperation systems, normally works under the constraint of zero division. Small force or velocity signals can cause the occurrence of zero division which ultimately leads the system to be unstable. This paper presents a novel switching time domain passivity control scheme for multilateral teleoperation systems which not only ensures the stability of the system but also avoids zero division. In contrast to bilateral teleoperation systems, the multilateral teleoperation system is much more complex as it involves increased number of master and slave hardware, multiple operators and transmission of multiple signals over the communication network. A new framework for the communication channel has been proposed which incorporates the use of weighting coefficients to give masters and slaves authority depending upon the requirements of the operation. As the switching time domain passivity control keeps the system passive all the time, the stability is guaranteed. The proposed control scheme is valid for n masters and n slaves. Simulations with two masters and two slaves are carried out to verify the effectiveness of the proposed scheme.