Research On Prescribed Performance Synchronous Control Of Telerobotic System Under Sensor Fault

The networked teleoperation system is widely used in accident rescue,space exploration,deep sea exploration,remote operation and other activities because of its advantages of remote operation,precision operation,human-computer interaction and anti-harsh environment.Considering the unknown,complex and variable operating environment described above,the risk of sensor failures in slave robot of the teleoperation system will increase significantly.The existence of the fault will cause the measurement value to deviate from the actual value,which inevitably endangers the stability,security and reliability of the teleoperation system.Thus,the control task of teleoperation system will be destroyed.In addition,the networked teleoperation system model has strong nonlinearity and it is difficult to obtain accurate system model in practical application.As the requirements of teleoperation system become more and more complex and accurate,it is far from enough to consider the stability of the system.The main control objective of this paper is how to design a control scheme to make the teleoperation system realize synchronous control while ensuring the transient performance of the system meet the prescribed requirements.The main research contents of this paper are as follows:(1)A control scheme of position synchronization and force tracking with prescribed performance is designed for the uncertain networked teleoperation system with sensor faults.Firstly,the position sensors of the slave manipulator are considered to be faulty,and a learning observer is designed to estimate the fault value.Secondly,in order to improve the transparency and flexibility of the master-slave manipulator,an ideal impedance control model is proposed,which divides the teleoperation master-slave system into two independent systems to achieve force and position coordination control.Furthermore,a fuzzy adaptive prescribed performance controller based on impedance framework is proposed to enable the teleoperation system to set the transient performance quantitatively in advance.Fuzzy wavelet neural networks are used to approximate the uncertain system model,and the prescribed performance function presets the position tracking error in a sufficiently small range.Finally,the absolute stability of the teleoperation system with time-varying delay is proved by using the absolute stability criterion.(2)A sliding mode observer based synchronous control scheme with fixed time prescribed performance is proposed for the uncertain networked teleoperation system in which both the position and velocity sensors of the slave manipulator are faulty.Firstly,a sliding mode observer is designed to estimate the faults of the position and velocity sensors of the slave manipulator,and RBF neural network is used to compensate the uncertainties of the system online.At the same time,a sliding mode adaptive law is designed to deal with external disturbances.Secondly,an approximate fixed time prescribed performance controller based on impedance framework is proposed.By combining fixed time control with prescribed performance control,a prescribed performance function with faster convergence rate is obtained.Then,a fixed-time terminal sliding mode control strategy is designed based on the prescribed performance control,which makes the synchronization errors of the teleoperation system converge to the preset range of the prescribed performance function within a fixed time,and further improves the transient performance of the teleoperation system,including overshooting,convergence speed and convergence accuracy.Finally,the convergence of the system is proved strictly by using Lyapunov stability theory.It can be seen from the simulation results that both the learning observer and the sliding mode observer designed in this paper can quickly and accurately estimate the constant or time-varying sensor faults of the slave manipulator.The control strategy in this paper ensures that the teleoperation system can not only achieve good synchronization performance,but also achieve the prescribed transient stability performance under the condition of sensor faults.