Study On Fuzzy Control Method Of Underactuated 2R Manipulator

Underactuated manipulator is a kind of multi-rods mechanical system with one or more passive joints. It has less input than DOF of system in number and can finish complicated task with less driving devices. Underactuated robot has light weight, low cost and needs less work energy because of reducing several drivers. However, it also has second order nonholonomic constraint character, the control method become much more difficult than full-actuated robot. It has become a new hotspot in the robot study field.In this paper, our study object is a underactuated 2R horizontal robot. Based on fuzzy control method which is a kind of intelligent control, we study the control problems of underactuated robot. And we also finished the control experiments of a underactuated 2R horizontal robot. Therefore, the feasibility and validity of this control method are validated.Firstly, the dynamic model in joint space of underactuated 2R robot is established with Lagrange equation. The dynamic coupling character between joints is analysed when passive joint is is fixed in two kinds of position. And two dynamic coupling indexs are compared in numerical value. The nonholonomic constraint character of system is proved in theory by analyzing the dynamic equation of passive joint.Secondly, based on fuzzy control theory, the problem of controlling passive joint position and tip path tracking is studyed. The fuzzy control rules are described by analysing the dynamic coupling character between joints. Then fuzzy controllers are designed respectively for two kinds of control problem. And the initial velocity of manipulator tip before path tracking are discussed.Thirdly, based on PMAC and DSP controller, two kinds of control systems are developed for the experimental study of underactuated robot. Several problems during developing system are solved, such as communication between devices, high precise timer and so on. Experiment control interface and data analyse software are also exploited. The whole control system provides software and hardware qualification for more experimental study of underactuated robot.Finally, the experiments of controlling passive joint position and several paths tracking of manipulator tip are finished by developed control systems. The experimental data indicates that fuzzy control method presented in this paper has high precision and good robust character for a underactuated 2R horizontal robot. And this control method don't rely on the dynamic model. It has good real-time character because of its simple arithmetic.