This paper describes the testbed telesurgery system that was developed in MIT's Human Machine Systems Laboratory. This system was used to investigate the effects of communication time delays on controller stability and on the performance of surgical tasks. The system includes a bilateral force-reflecting teleoperator system, interchangeable surgical tools, audio and video communication between the master and slave sites, and methods to generate time delays between the sites. To compensate for the time delays, various control schemes were investigated, leading to the development and selection of fuzzy sliding control (FSC). With a stable teleoperator system, experiments in performing a variety of surgical exercises were conducted. These looked at the performance of a team of a telesurgeon and local assistant given a number of different time-delay scenarios, including synchronous and asynchronous force and audio/video feedback. The results of the research project include the development of the novel FSC algorithm, data on how time delays degrade performance of surgical tasks, and recommendations on how telesurgery should be performed to accommodate telecommunication time delays.

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The robustness of bipedal walking robots can be enhanced by the use of adaptive control techniques. In this paper, we extend a previous control approach. "Virtual Model Control" (VMC) [6] to create "Adaptive Virtual Model Control" (AVMC). The adaptation compensates for external disturbances and unmodelled dynamics, enhancing robustness in the control of height, pitch, and forward speed. The state machine used to modulate the virtual model components and to select the appropriate virtual to physical transformations (as in traditional VMC) is also used to inform the adaptation about the robot's changing configuration. The design procedure for AVMC is described in this paper and simulation results are presented for a planar walking biped.

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A master-slave telerobotic surgery system has been developed in Human Machine Systems Lab. at MIT. This system is composed of a master-slave telerobotic system, a two-way video/audio transmission link, a control data un/c and a laparscopic surgery simulation platform. With video, audio andforcefeedback a surgeon can conduct telelaparoscopic surgery for a remote 'patient' by means of the master-slave telerobotic system. However, the force feedback can go unstable when the communication time delay of the control data link is larger than roughly 0.2 seconds. Therefore designing a stable force feedback control becomes an important issue for a telerobotic surgery system.This paperproposes a new approach to achieve stableforce reflecting teleoperation control under time delay Fuzzy Sliding Control (FSC). FSC is based on the conventional fuzzy control and sliding mode control both of which have been proven robust and stable. The design methodology of FSC includes the following major parts: a fuzzy sliding control law, rule tuning in the phase plane, and soft boundary layer tuning. FSC can easily be modfled and applied to deal with the uncertainties and human interactions in teleoperation. In our research, a novel control structure which consists of FSC and a frzzy super'isor has been implemented in our high bandwidth master-slave telerobotic system. It has been shown that this approach has stableforce reflection and good tracking accuracy for loop delays up to 2 seconds. Experiment results are described in the paper.