Research On Adaptive Trajectory Tracking Control Of Manipulator System With State Constraints

The manipulator system has made outstanding achievements since the simple manipulator development.Combined with computer automation,its application scope involves a wide range.In industrial applications,systems encounter various types of constraint problems.In order to expand the application of the manipulator in actual industry,the corresponding conditions should be met according to different operation requirements.In other words,the uncertainty and inevitable external interference in the system as well as the constraints of different requirements should be solved,so that the end-effector of the manipulator system can operate stably on the preset trajectory.In this paper,the uncertain manipulator system with external disturbance under full state constraint is studied as follows:1)The adaptive control problem of a second-order nonlinear manipulator system with asymmetric time-varying full state constraints is studied.Firstly,a log-type barrier Lyapunov function is constructed because the system has all state constraints and uncertainty.Then a controller which satisfies the asymmetric full state constraint is designed by combining neural network and adaptive control algorithm.Through Lyapunov analysis,the boundness of the system signal is proved,and the error converges to near zero to satisfy the requirement that all states are constrained.Finally,the performance of the designed controller is verified by a double-joint manipulator system.2)Aiming at the uncertainty and interference of the manipulator system with time-varying symmetric constraints,an adaptive controller based on neural network approximation is designed by using the integral barrier Lyapunov function.Firstly,the manipulator system is mapped to a nonlinear system with multiple inputs and multiple outputs.By combining the Lyapunov function of time-varying integral barrier with the model of the manipulator system,this not only overcomes the conservative restriction and the defect that the Lyapunov function of traditional barrier needs to convert the state constraint to the error constraint.It also ensures that each state of the system is within its own constraints.Then we design the appropriate controller and the adaptive law by using the Backstepping method.The derivative of Lyapunov function with integral barrier is calculated by means of the integral mean value theorem.Lyapunov theorem can guarantee the stability of the closed-loop system under the proposed scheme.At the same time,ensure that the output signal can track the predetermined trajectory within a small error range.Finally,a simulation example shows the effectiveness and feasibility of the proposed method.