Design Of Direct Torque Control System Based On Flexible Joint

People have not satisfied to the robot which only can complete a simple, repetitivework with the development of robot technology. People are beginning to pursue to achievethe robot technology which can assist human to complete a variety of complex task. Therobots need to physical interactionwith people or unstructured environment in the processof cooperation. The above demand need for special design from the aspects of jointmechanism and control etc, because the design idea of using traditional industrial robots ishard to realize.Nowadays, it becomes an important development direction of robot technology thatrobots able to complete different tasks and in harmony with people or environment. Robotresearch institutions were carried out research in the directionand obtained many researchachievementsboth at home and abroad. Researchers show great interesting in the study ofthe flexible joint, which is based on the serial elastic actuator (abbreviation: SEA). SinceSEA has elastic element, it can buffer the external impact and provides the passivecompliance such that manipulator can contact safely with both human and environment. Inaddition, we can use the inside elastic element to measure the torque exerted on this joint.The torque feedback loop is established and the joint torque is controlled accurately.FPGA-based control system is built on the SEA developed by ourselves. Then directtorque control technique, which uses phase currents to calculate the joint output torque andforms the motor torque feedback, is adopted to improve the SEA’s dynamic performanceand to implement joint torque fast tracking. Its feasibility is validated by computersimulation. Furthermore, velocity-, position-and torque-loop can be formed by two built-inposition sensors placed behind and before the elastic element respectively so that highdynamics, safety and high performance are fulfilled.