Design Of The Modular Joint For Three-Branch Robot

Modular robot is composed of joint units and link units that can be assembled into various robot configurations for a diversity of task. Each modular joint has a standard mechanical and electric interface. The distinguished merit of modular robot is its flexibility, reliability, easy-maintenance and reconfiguration. Therefore, it has wide application foreground. According to the idea of modular design in the "863" National Project, Intra Vehicular Manipulator Comprehensive Service System for Spacelab, a prototype module is to be developed.On the basis of analysis of modular joint at home and abroad, one project is presented and analyzed. According to the tasks of the modular robot, the maximum torques of each joint are gained by taking into account module by module from top to base. Then a model of the relationship between the tolerance and the position error of the robot gripper is built. The maximum position error can be gained by the model with error parameter. The design specification of modular joint is fixed and the type choice of main components is done.According to the technical requirements of three-branch robot, a modular joint with a standard mechanical and electric interface is developed, which includes many systems, such as mechanical system, driver system, sensor system, control system and power system. A new torque sensor which based on strain gauge approach and with four elastic beams in cross distribution is designed in detail, and it has the overload protection ability of joint torque and bending moment. The paper have accomplished the design of modular joint, including material selection, detailed structure design, cabling design, system integration design and multiple linking module design. Three-dimension modeling of the parts and components of modular joint, virtual assemble and motion simulation of modular joint are carried out successfully using Pro/E software. Finally, with ANSYS software, intensity analysis is made under maximum force working conditions, the intensity calculation of and two rolling bearings is also accomplished. The results show that the intensity can meet the design requirements.According to the requirement of the project, a joint control system based on DSP is put forward. The hardware design of the control system is inroduced and the circuit of DSP controller, driver controller, signal feedback unit and CAN communication unit are designed in detail. Based on the working principle and the functional requirements of modular joint, the software design idea of control system is introduced, the design process of main program and subprograms is discussed as well. According to the model of modular joint, an effective system controller is developed. Finally, algorithm analysis and simulation of the multi-loop control method are completed, the results are relative well.