FUZZY-LOGIC CONTROLLER FOR A SCARA ROBOT WITH SYNCHRONOUS NETWORK

A prototype SCARA robot with synchronous network control interface has been designed and constructed. This hardware structure can be employe d and extended to simultaneously control multi-targets with a distribu ted local controller by the monitoring of a centralized controller thr ough a synchronous network. Here a centralized controller is designed to control a SCARA robot without local controllers for each degree of freedom. Since the robotic manipulator has a complicated mathematical model, it is difficult to design a control system based on the multi-v ariable nonlinear coupling dynamic model. The model-free fuzzy logic c ontrol approach has gained much attention. The traditional fuzzy logic controller does not have a learning capability. It needs a lot of eff ort to search the optimal control rules and the shapes of membership f unctions. Due to the system's time-varying behaviour, the required tra cking accuracy is difficult to achieve by adjusting the fuzzy rules on ly. To simplify the implementation problems of fuzzy control, the conc ept of pre-correction of the system output deviation is added to the f uzzy control structure using a grey predictor. The experimental result s show that this fuzzy controller has improved the trajectory tracking accuracy and simplified the searching effort of fuzzy rules and membe rship functions obviously.