Research On Modular Compliant Jointof Light Weight Robotic Arm

Modular robotics is an important research aspect in the field of robotics in the future. It has the advantages of good flexibility, short design period, low cost and it is easy to maintain. This dissertation is mainly focused on the joint modular design of the automatic assembly light weight manipulator that has the force perception and the compliant control function to meet the need of the rapid development of the assembly work.Modular design idea is adopted in the light weight robot design, which helps improving the interchangeability and maintainability of the mechanical arm. According to assembly task requirements, main functions and technical indexes of the modular joint can be gotten and the overall scheme of the modular joint has been designed, in which mechanical components, drive components, sensor components and control components are integrated into one joint. Then, the selection of the key parts has been finished, including DC permanent magnet servo motors, harmonic reduction devices, encoders, brakes and bearings etc. Finally, by combining key components into a whole, the modular joint has been constituted. Its transmission is stable and reliable. It has high degree of integration and the standard mechanical and electrical interface to walk lines internally.According to the designed joint, the dynamic model of the flexible joint has deduced and the closed-loop simulation system has been established, including the current, speed and position loop. Based on this system, the verification of the joint control law has been finished, providing the basis for the actual controller design. By analyzing the load capacity and operation condition of the mechanical arm, the conclusion that the id=0 magnetic field oriented control strategy and SVPWM is suitable for the PMSM, has been drawn.In order to meet the real-time, open and flexible control requirements of the integrated joints, a servo control system based on FPGA has been developed, which involves the timing planning module, the current sampling circuit and its driver module, the current regulating module, the vector transformation module, the PI regulator, the trigonometric function calculation module, the space vector pulse width modulation module, the encoder SSI bus interface circuit and its acquisition module, integrated sensor signal acquisition and integration, servo control, motor drive etc. This system can realize the sensor signal acquisition and integration, servo control, motor drive and other functions.Finally, the experimental prototype has been finished. The SVPWM and the permanent magnet synchronous motor vector control has been verified and tested on the experimental prototype. The experimental results have shown that the designed flexible joint controller has a good current, speed and position following performance, achieving the expected goal.