The Study Of Fuzzy Logic Sliding Mode Control On 2-DOF Parallel Mechanism Control

Parallel robot is a new kind of robot which has the features of big toughness,high bearing capacity, small error, high precision, good dynamical capacity and so on. It has the complementarity with serial robot which has been applied widely and expands the applied field of robot. With the robot technology developing, robot has already entered into every corner of our life. However,the kernel of robot is the control system.The degree of the development and the power of the function usually have direct mutuality with the performance of the controlling system.The robot dynamics equation is highly nonlinear, mutual coupling,for such complex nonlinear control system, the traditional method is difficult to recruit effective control, the sliding mode variable structure control has been applied to parallel mechanism widely because it has distinct and ideal robustness and holds the invariance for the change of system parameters,outside disturbance and uncertainty of the system ,and its algorithm is very simple. But for the sliding mode variable structure control system, it will produce high frequency chattering around the sliding plane after the system state getting to the sliding plane , and the control variable of the system will also produce high frequency chattering so that the system would not be put into practice. The chattering phenomenon is a big barrier for the sliding mode control to apply to engineering practice, therefore, the chattering phenomenon becomes a research focus of VSC.In this paper, for the GPM series 2-DOF parallel mechanism maded by The Googol Technology (HK) Ltd in Shenzhen, based on the theory of variable structure control and fuzzy control, a fuzzy sliding mode variable structure control strategy is designed, using the variable structure control system to ensure stability and good dynamic performance in sliding phase and the fuzzy controller adjust the character in fuzzy phase to weaken the chattering bringed by the uncertainty and the external interference so as to achieve better control results.At the last, the simulations of the control system and the test on parallel mechanism drived by ACservo are performed by the computer language MATLAB/SIMULINK6.0 and the control software based on the VC++ respectively. The results demonstrate that the control scheme designed is feasible and effective.