Multioperator Teleoperation of Multirobot Systems with Time Delay: Part IITestbed Description

The Mechanical Engineering Laboratory (MEL)1 has been developing coordinated control technologies for multi-telerobot cooperation in a common environment remotely controlled from multiple operators physically distant from each other. Previously, we learned about how the transmission delay over the network deteriorates the performance of telerobots through simulations. To overcome the operator's delayed visual perception arising from network throughput limitations, we have suggested several coordinated control aids at the local operator site. The testbed facilitates experiments with physical robots for validation beyond simulation. This paper mainly discusses the details of the testbed and investigates the use of an online predictive simulator to assist the operator in coping with time delay over the network. Practically, a common data relay station is suggested to reduce the travel distance of the master data over the network and enable multirobot predictive simulation at one's master station. Operators control their master to get their telerobot to cooperate with the counterpart telerobot using the predictive simulator as well as video image feedback. Specifically, exploiting the audio-visual resources of the simulator, operators can detect a priori the possibility of collision and coordinate conflicting motions between telerobots. We have demonstrated an object rearrangement task by two telerobots and two operators via an ethernet LAN that is subject to simulated delays and evaluated the validity of the online predictive simulator in Multioperator-Multirobot (MOMR) tele-cooperation. On April 1, 2001, MEL merged into the National Institute of Advanced Industrial Science and Technology (AIST).