Time-delay analysis and estimation of internet-based robot teleoperation system

Time-delay is unavoidable and randomly time-varying for teleoperation robot system based on Internet, and also most difficult obstacle between local operators and remote robots. In the paper, we first analyze RTT (roundtrip time or delay) time sequences collected by large numbers of test, and find that RTT time sequences between any two network nodes are irrelevant, so it is irresponsible to estimate the value of network time-delay by modeling methods. But it is also shown that time-delay at any period of time accords with parallel shift gamma distributing (PSGD) instead of Gauss distributing or white noise distributing, and probability density curves of time-delay can be described by finite kinds of probability density of PSGD. It, mean value estimation of network time-delay, therefore can be obtained by forecasting PSGD of time-delay. Then moment estimation method can be used to estimate mean value of network time-delay by estimating parameters of PSGD.