Research On Six-DOF Master-Slave Telerobotic System With Force Feedback

Teleoperation system with master-slave robot at the core can be complex manipulated in uncertain or extreme environment (such as space, seabed, radialization, battlefield, etc.). The quality of the operation is correlated with the ability of getting information (such as force, vision, etc.) about the slave side.The dynamic reciprocity between robot and operated object can be felt by teleoperation system on account of the force telepresence and vision telepresence,which can make the operator accomplish complicated and exact operation. Nowdays,the research of technology related with telepresence is gaining more and more attention.Vision telepresence can provide most information for teleoperation, it is of great help for the human operators'cognition the environment being operated.When the robot is contacted with the environment and only has vision telepresence system, operators cannot acquire the real sense. Only with the guidance of force telepresence can operators accomplish these complex tasks well.Experiments on teleoperation systems also indicate that force and tangency senses can greatly enhance the efficiency and the accuracy of teleoperation systems. Thus it can be seen, force telepresence can provide great help for teleoperation systems, and it can greatly enhance manipulation performance.In this paper, combines with the Ministry of Education excellent youth teacher fund " Research on long-distance manipulate engineering robot with force feedback " item, we have set up a telerobot system hydraulic drove with force feedback which is called six-DOF bilateral servo system after analyzing the telerobot systems with telepresence, especially those with force telepresence in home and abroad. In consideration of the force feedback, position follows bad and other problems existing in the current bilateral servo strategy, we apply a new master-slave bilateral servo system and we designed a fuzzy-PD controller to control the tele-robot system.Besides,in order to restrain the disturbance introduced by the dynamic discrepancy between the different hydraulic cylinders,we introduce a state observer for disturbance compensation. We have validated that the new control strategy is feasible and the fuzzy-PD controller is better than common PD controller ,as well as that the state observer can compensate the disturbance well when we did experiment on the six-DOF tele-robot system hydraulically droved with force feedback.Combined the research of theory and experiments, we have accomplished the main research tasks as follows:1. We have set up a six-DOF telerobot system with force feedback based on electron hydraulic servo system. Characteristics are teleoperation, high precision position control, force telepresence. This system has a good sense for setting up and studying more complicated telerobot system. Besides, this system makes it easy to make experiment for bilateral servo theory.2. We have built up the mathematics model of the electricity liquid servo system, analyzed and solved the electron hydraulic servo valve,hydraulic cylinder controlled by servo valve and servo valve's function in detail based on one-DOF electricity liquid servo system.The open loop transfer function provides reference mathematics model for designing controller and for designing state observer.3. We have designed fuzzy-PD controller for electron hydraulic servo system. First, we designed a common PD controller and get its two parameters, then, we designed a fuzzy-PD controller to control the telerobot system. Compared with the common PD controller, the fuzzy-PD controller could change its parameters on line. The result from experiment shows that fuzzy-PD controller is better than common PD controller to control the system.4.We have designed a state observer for disturbance compensation.When analysing the system,state feedback will provide us with more emendation information,which is applied extensively to optimizing control as well as disturbance restraining or eliminating.Because of the dynamic discrepancy between the different hydraulic cylinders and the zero drift caused by manufacturing precision as well as temperature changes, it is hard to control the master robot's position very precisely. As a result, we design a state observer for disturbance compensation based on the state observer principle.5.Based on the telerobot system with force feedback we have done experiments experiments with load and without load respectively, we have validated that that the new control strategy is feasible and the fuzzy-PD controller is better than common PD controller.The researches in this paper are aimed to electron hydraulic servo telerobot system with force feedback, which uses the improvement new bilateral servo control strategy. With high prompts by force telepresence, which can make human operators perceive veritably the dynamic reciprocity between the robots and environment, telerobot systems can accomplish complex tasks under inaccessible environment. The researches on control strategy and experiments in this paper provide experience and key technology for teleorobot systems'utilities, and as a result they will greatly enhance work efficiency in teleoperations.