Research On The Force Feedback Master Manipulator And Time Delay Control Of Teleoperation Orthopaedic Surgery System

The development of teleoperation surgery make remote medical service provide evaluation, diagnosis,treatment and follow-up care patient become possible,which can improve the quality of medical service. Through network communication technology combined with teleoperation surgery, master-slave teleoperation surgical robot system was proposed based on the network operating systems. However, it has lots of disadvantages described as follows. Firstly, the existing master manipulator is extremely expensive and cannot own enough operating space. If doctors use universal master manipulator to accomplish a particular task surgery, they may not adjust appropriately according to their own need because of lack of targeted design so that they feel dicomfortable for long working hour, which limits the existing force feedback master manipulator applications. Secondly, the communication time delays in the process of the master-slave communication exist, which will reduce the control performance of the system. For the sake of security, communication time delay problems during surgery should be considered.Based on the action requirements of the orthopedic surgeon and the characteristics of the robot, the simple structure and posture configuration has been identified the force-feedback master manipulator for orthopedic surgery has been developed. The device was made up of parallel mechanism with three-dimensional force feedback and serial mechanism to get angle information. Based on the analysis of workspace and operation performance, the size optimization design of the master manipulator has been conducted.When the force feedback master manipulator provides force feeling for the operator, self-balancing problems of the master robot should be solved to overcome the influence of gravity and reduce hand fatigue during operation. Therefore, the force feedback model was established and the relationship between the joint output torque and the force was acquired. A model error compensation method was adopted based on BP neural nework, which provided effective control method for the gravity compensation and force feedback.In addition, in order to improve the real-time, research on its own delay has been discussed. Multi-threads and multi-events technology were applied to reduce algorithm time-consuming.Through analyzing network teleoperation system delay, based on network delay range determined and combined with H control method, the system was integrated into a standard form of H control using technology. Mixed sensitivity robust controller design method was proposed to make the network time delay within the range which H robust controller can solve, which can solve the time delay caused by the Internet transmission environment. Since mixed sensitivity weighting function design in robust controller design mostly depends on the designer’s experience, artificial immune algorithm constraint-based was applied to optimize the weighting function, which avoided the disadvantages of traditional method.The self-developed force feedback master manipulator was used as the master force feedback device. The orthopaedic reset robot was considered as the slave controlled object. And a teleoperation orthopaedic reset surgery system experimental platform was built. The reset robot position tracking performance in the free space and force feedback performance in the confined space can be verified through experiments. Finally, the experiment of long bone reduction was built, experimental results showed that the designed controller can guarantee a master-slave system better transparency and stability in the case of time delay occurring and the one-way maximum known no more than 2 seconds, the reduction achieved valuation criteria or orthopaedic reset surgery.