Research On Finite-time Trajectory Tracking Of Rigid Manipulator Based On Sliding Mode Control

As a classic method, finite-time tracking exists in various practical applications including engineering, agriculture, medicine and etc. Both efficiency and accuracy should be considered in this problem. Due to its practical significance, this problem attracts attentions world widely and makes a big progress in control application. However in the early days of control study, there still exist two key problems in dealing with finite-time problems. On one hand, the design of controller usually relies on the initial information, which makes the controller lack of anti-interference and robustness. On the other hand, in practical applications, the uncertainty of system will result in chattering phenomenon, which could lead to an inferior performance or even destroy the system stability. To solve the mentioned two problems, terminal sliding mode control, which is a famous robust control method, has been imported in this thesis and achieves a great success in the finite-time trajectory tracking control of a manipulator.Here considers a manipulator as objective and studies several categories trajectory tracking control problems based on finite-time terminal sliding mode. The contributions and work are given as follows:First, for the conventional sliding mode variable structure, linear sliding mode surfaces and several kinds of laws are investigated in trajectory tracking control.Once the system states are in the sliding mode surfaces, they will achieve the control objectives quickly. Numerical simulations show that the sliding mode control can be applied to a variety of systems with uncertainty parameter, but cannot guarantee the convergence in finite time.Second, for the requirements of efficiency take the use of methods like transform trajectory tracking control into chained form or construct Lyapunov function to give the corresponding implementation like local or global tracking for some of the tracks who meet the conditions. Compared finite-time closed-loop control system with non-finite-time closed-loop control system, finite-time closed-loop control system has better robustness and disturbance rejection performance. Numerical simulations show that the terminal sliding mode control makes the system converges to stable-state in finite time, which breaks the limitation of asymptotic convergence of conventional sliding mode control under the conditions of linear sliding mode, and terminal sliding mode control can effectively eliminate chattering when solving nonlinear system control problems.Third, a novel sliding model surface is imported into design of controller, which not only guarantee the established requirements but also optimized the system performance. The novel controller makes system meet the target of finite-time tracking and the numerical simulation shows that the chattering phenomenon has been eliminated dramatically, which strengthen the tracking control accuracy.Finally, after compared the results, advantages and disadvantages of proposed methods are summarized. Based on the analysis of the performance, future work has been proposed.