Research On Time-delay Control For Robot-assisted Remote Orthopedic Surgery

In recent years, the technology of teleoperation has developed quickly. Sincetelesurgery can break the geographic restrictio n between patients and doctors andexpand the medical resources to the remote areas, it has application prospect in theremote saving. However, the existence of time-delay through network which isinevitable in telesurgery can make the system unstable and even pose threat topatients’ lives. Therefore, research the control of telesurgery under internet hasgreat significance to the development of telesurgery.In order to research the time-delay control of telesurgery, the experimentplatform is established, which establishes the stable and accurate networkcommunication between master hand and slave hand with different networkingprotocols. Based on the characteristic of the platform, RTT method is used tomeasure the local time-delay and Internet time-delay, as a result, we acquire thefigure of local time-delay under CAN bus and the Internet time-delay based on UDPand TCP/IP protocols and analyze the characteristic of them.According to the relative stable and controllable characteristic of localtime-delay, the strategy of multithread and multi-event driven is taken to reduce thelocal time-delay, which acquires a stable, controllable and small local time-delay.Meanwhile, derivative approximation is used to improve the original gravitycompensation algorithm, which reduces time-consuming, further reduces local delay,guarantee the stability of master hand under local time-delay.In the aspect of Internet time-delay control, considering the time-varying anduncontrollable characteristic, a data loss and disorder processing strategy based ondata label is put forward, which acquire a higher rate of accurate forecasting.Aiming at the influence of Internet time-delay to the stability of the system, PIDand feedback loop is proposed to improve the internal model controller, and theparameters of the system are optimized using an improved particle swarm algorithm.Through simulations, the improved internal model controller is testified to be betterthan the norma l internal model controller in both stability and the ability ofanti-interference, keeping a good stability and following performance under variedtime-delay.At the stage of experiment, the practicability of master-slave teleoperation istestified and the network time-delay is simulated under the condition of local areanetwork, testifying the stability of the system. Through the teleoperationexperiments under the wide area network, which is between Harbin and Beijing, the practicability of remote surgery under the Internet environment is testified.Meanwhile, the data loss and disorder processing strategy based on the data label isalso testified under the real network environment.