An improved prescribed performance control approach of trajectory tracking control for six-axis manipulator

As a highly coupled multi-input multi-output nonlinear system, when traditionally prescribed performance control methods are used for robotic manipulator design, control failure may occur if tracking errors exceed preset performance boundary functions. To overcome this critical issue, this study formulates an improved prescribed performance control method. Firstly, the dynamic equations of a six-axis robotic manipulator are established. Then an improved prescribed performance control method is proposed, which is combined with a non-singular fast terminal sliding mode control method to design the robotic manipulator control system. Meanwhile, the convergence of the controller is analysed using the Lyapunov stability theory. Finally, trajectory-tracking control simulations are conducted for the six-axis manipulator under typical working conditions. The results show that the proposed control method can solve the problem of tracking errors exceeding boundaries, significantly improve trajectory tracking accuracy, and demonstrate strong robustness against external disturbances.