Internet-based Teleoperation System Delay Control Study

Teleoperation systems especially the ones with force telepresence extend the perceptional and operational ability of operators significantly. They have been applied to many areas, such as space projects, deep ocean detecting, nucleus industry, medical treatment, and so on. While teleoperation systems provide a great help for the operator's security and work efficiency, they suffer from serious problems resulting from inherent time delay in themselves. When the time delay is big enough or varying, the system will fall into instable and will not work normally. Nowadays, with the fast development of the network technique and the use of the Internet all over the world, teleoperation systems based on Internet have been paid a great attention by scholars. They put their focuses on the system's instability, deterioration of the transparency and loss of the force telepresence brought by random time delay, infinite, package loss and misorder in network.In order to solve the problems above, this paper presents a novel control method-building an internal model control structure for the teleoperation system with force feedback: a) For invariant delay systems, slave manipulator local feedback controller and internal model controller were designed to achieve velocity and force tracks of the two manipulators. Because of the predictive internal structure, force teleprecence went well. b) For variable delay systems, velocity tracking control loop was not changed and force tracking employed robust control. While the transmitting time delay with definite bounds was regarded as uncertainty (or perturbation) of controlled plants' parameters, H_∞ -optimal control theory was applied to the control system and determined the bounds of the controllers' parameters, which can guarantee the robust stability and optimal robust tracking performance under arbitrary bounded time delays. Effects on the stability and transparency brought by varying time delay have been reduced as much as possible. c) Based on the analysis of the Internet time delay characters, this paper discussed the case how to use the H_∞ -control method to Internet teleoperation systems. New data receiving-sending algorithm and delay control algorithm were given to handle the network delay's infinity, packet loss and misorder, by which the Internet time delay were normalized to the range of H_∞ -control. In this way, the robust control method based on internal model given before must be an efficient scheme to keep the stability and good transparency even under Internet time delay circumstance.The above three parts are presented step by step and the first two is the basis of the last one. They can also be used solely. The whole control system is built on the internal...