Abstract
Background: As a control strategy of industrial robots, sliding mode control has the advantages of fast response and simple physical implementation, but it still has the problems of chattering and low tracking accuracy caused by chattering. This paper proposes a new sliding mode control strategy for the application of industrial robot control, which effectively solves these problems. Methods: In this paper, a deep deterministic policy gradient–nonlinear nonsingular fast terminal sliding mode control (DDPG–NNFTSMC) strategy is proposed for industrial robot control. In order to improve the tracking control accuracy and anti-interference ability, DDPG is used to approach the uncertainties of the system in real time, which ensures the robustness of the system in various uncertain environments. Lyapunov function is used to prove the stability and finite time convergence of the system. Compared with the nonsingular terminal sliding mode control (NTSMC), the time to reach the equilibrium point is shorter. With the help of MATLAB/Simulink, the tracking accuracy and control effects are compared with traditional terminal sliding mode control (TSMC), NTSMC and radial basis function–sliding mode control (RBF–SMC), the results showed that it had the advantages of nonsingularity, finite time convergence, small tracking error. The motion accuracy and anti-interference ability of the uncertain manipulator system was further improved, and the chattering problem of the system in the motion process is effectively eliminated.
Highlights
In recent years, with the development of industrial robots, nonlinear, external interference, a variety of uncertainty problems appear, and the performance requirements of the control system are more and more strict
We design a new NNFTSMC sliding surface for the manipulator with uncertain dynamic model based on traditional nonsingular terminal sliding mode control (NTSMC), and solve the reaching law and design the controller based on the sliding surface
A DDPG–NNFTSMC control strategy was proposed to solve the problem of chattering and chattering caused by traditional sliding mode control, which is successfully applied to manipulator systems with uncertain dynamic characteristics
Summary
With the development of industrial robots, nonlinear, external interference, a variety of uncertainty problems appear, and the performance requirements of the control system are more and more strict. When the state trajectory reaches the sliding surface, it is difficult to slide strictly into the sliding surface to the equilibrium point, it passes back and forth on both sides of the sliding surface, which is called chattering [5,12], and it needs an accurate dynamic model for the control object To solve these problems, some research effects propose a series of solutions to eliminate the uncertainty, chatter, and error of the system as much as possible [13,14,15,16,17,18,19,20,21]. With the help of MATLAB/Simulink, the tracking accuracy and control effects are compared with traditional terminal sliding mode control (TSMC), NTSMC and radial basis function–sliding mode control (RBF–SMC), the results showed that it had the advantages of nonsingularity, finite time convergence, small tracking error. The motion accuracy and anti-interference ability of the uncertain manipulator system was further improved, and the chattering problem of the system in the motion process is effectively eliminated
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