This paper presents a bilateral robot system, which is driven by the static friction-free drive system and implemented on the real-time network structure. The goal is to realize a force reflecting bilateral teleoperation with haptic impression transmission over computer networks. The paper considers two subjects relating to the bilateral robot. The first is static friction, which degrades the performance of manipulation and results in a poor haptic impression. A new transmission mechanism named twin drive system developed by the authors resolves this problem. The transmission mechanism, which resembles the differential gear of automobiles, is essentially free of static friction. This static-friction-free motion greatly contributes to the broad range of motion control applications. The second subject is the time delay of the network, which may cause serious problems such as instability of the feedback system. To avoid such delay, the authors developed a new real-time network protocol stack (RTNP). The detailed mechanism of the twin drive system and architecture of the RTNP are presented, and the control scheme and experimental results are also shown.
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