Three Degrees Of Freedom Hydraulic Servo Joint And Its Control Method

Robot joint is one of the most important parts and a basic unit of the robot, for the performance of which will determine the whole function of the robot system. On the basis of summarizing all kinds of latest research achievements on the robot joints, a novel hydraulic servo joint, which has three degree-of-freedom (3dof) and the characteristic of motion decoupling, is proposed and studied.Firstly, according to the idea that the control system of a 3dof robot joint will be greatly simplified if the joint can meet the demand of motion decoupling, the idea of motion decoupling is analyzed, and the concept design of a novel 3dof hydraulic servo joint, which has the characteristic of intersection vertically and motion decoupling, is put forward and discussed. Then the resistance of the inner servo valve core in the 3dof hydraulic servo joint has been tested, which will make a solid foundation for the further structure design.Based on concept design, the basic demand of structure design is analyzed. Modern design, such as optimal design, 3D design and virtual design, are applied to the structure design. Then the assembly drawing is finished.In order to eliminate the position tracking errors caused by the dead zone, the dynamic model of this hydraulic servo joint is established by the Lagrangian method and hydraulic system theory. A control compensation method with adaptive-network-based fuzzy inference system (ANFIS) is presented by comparing the advantages and disadvantages of several control methods in position tracking problem. The results of the simulation show that the dynamic system is steady and the method is effective.After the test prototype of the joint is manufactured, the experiment platform of the joint system has been set up on the basis of the basic demand of test system. Then the function of the joint system has been tested and the results show that the joint has attained many anticipated achievements.The joint has the merits of novel conception, compact structure, reasonable layout, large output torque, convenient to control etc. We think firmly that the manipulator based on the novel joint will play an important role in the technical enhancement and popularization of the industrial robot.