Research On Time-delay Robot Network Control System

Robot networked control system can enhance the safety and convenience of human exploration for unknown environment,and use robot to replace human to work in some dangerous environment.Due to the interaction of various components in robot networked control system,there will inevitably be network delay,which will affect the control performance of the system and even destroy the stability of the whole system.Therefore,it is necessary to design effective control strategies to reduce the impact of network delay on the system.In this thesis,the joint position tracking problem of robot networked control system with network delay is studied.The main work is summarized as follows:1)For the problems of random delay and packet loss in robot networked control system,an optimal predictive compensation control method is designed.Firstly,a state observer is designed to obtain the state information of the robot at the current moment,so as to predict the state information of the robot at the future moment.The controller uses the state information of the robot and rolling optimization to calculate a control sequence containing the control input each time.The time delay compensator obtains the current time delay by the time stamp,and selects the appropriate control input from the control sequence to compensate the time delay and control the robot at the same time.The double-joint robot networked control system is simulated.The results show that the proposed method can effectively compensate the random delay and packet loss in the robot networked control system.2)For the problems of time delay and packet loss in robot networked control system,an event-driven feedback control strategy is proposed.The method first determines whether the robot's position tracking trajectory error meets the preset error range.When the error does not meet the preset error range,the controller performs the control action.The convergence of the position tracking trajectory error of the controlled robot is proved,and the double-joint robot networked control system is simulated.The results show that,comparing with the traditional time-driven control method,the event-driven control method not only has better control performance and stability,but also saves network resources,reduces the probability of network blocking,and makes the system more reliable.3)For the problems of disturbance in robot networked control system,an event-driven control method is designed,which combines the disturbance observer and event-triggered mechanism.The random time delay in the network is considered,while the disturbance is compensated.When the controller determines whether the output error of the controlled robot meets the preset event or not,it receives the disturbance observation value from the disturbance observer.When the controller determines whether the output error of the controlled robot meets the preset event or not,it receives the disturbance observation value from the disturbance observer.If the system output error does not meet the preset event,the controller uses the system output error and observed disturbance value to calculate a new control input to replace the original control input signal,otherwise,the controller maintains the control input in the previous time.The stability and convergence of the robot networked control system are proved.Finally,the double-joint robot networked control system is simulated.The results show that the proposed method can make the controlled robot have good position tracking performance under the influence of external disturbance and network delay.