Research Of Trajectory Tracking Control Method For Manipulator Based On Fuzzy Torque Control

Along with the rapid development of science and technology, robot technology has been widely used in industry productions and daily life, especially playing an important role in the military and the outer space exploration fields. As one of the most used robots, the MIMO control system has the characteristics of coupling nonlinearity, time variation and so on. The trajectory tracking control robot arm as the research focus of the manipulator, the desired trajectory of each joints are required to track the desired trajectory. When the dynamics model of the manipulator is known, the existing control algorithm can solve the tracking control problem of the robot arm; however, in practice, the dynamics model of the robot is impossible to obtain accurately. There are some uncertainties such as random disturbances, nonlinear frictions and load changes. Therefore, it is valuable to study the control method manipulator with more adaptability.In this paper, the robot system with uncertainties is regarded as controlled object, and focused on the control algorithm research of the robot trajectory tracking control.Firstly, in this paper, the method of D-H is used to analysis the kinematics model of the robot arm. On this basis, the Lagrange method is used to establish the dynamic model of the robot arm, then simplified the dynamic model to build the model of the manipulator. Secondly, the dissertation gives a description about PD control for manipulator pointing tracking control and the computed torque control for time varying trajectory. It can be seen from the simulation results that the precision of the control of the manipulator trajectory tracking is not high. This paper, the fuzzy control is added to the calculation of the torque control, combining the advantages of fuzzy control and the method of computed torque can reduce the manipulator trajectory tracking error and improve the adaptability.Finally considering the uncertainty of the control of the dynamic model of the manipulator, on the basis of fuzzy torque control proposed two kinds of control method, that is fuzzy torque control based on the sliding mode variable structure control (SMVSC) and fuzzy torque control based on the fuzzy sliding mode variable structure control (FSMVSC). In this paper the dynamic model of robot arm is divided into two parts, this article will adopt the thought of "divide and conquer". The fuzzy torque controller is used to control the nominal parameter part of the robot arm. The SMVSC is applied to compensate the effects of the nonlinear friction of robot arm and the dynamic model error. Simulation results show that the controller can achieve a high accuracy in tracking performance in the case of model uncertainty and unknown parametric changes in the system. In order to further weaken the chatting, the fuzzy torque control method based on fuzzy variable structure compensation is proposed. The new hybrid compensation controller can make the manipulator to achieve asymptotic stability, and the position tracking error is small, and it can also reduce the chattering of variable structure control.