Research On Control Of Compliant Robot With Nonlinear Stiffness Actuators

With the beginning of the industrial revolution,the robots that liberated the labor force began to flourish.In the 21 st century,people's living standards have greatly improved.People are paying more attention to entertainment,service,medical care and exploring the needs of the unknown world.Therefore,new robots for HRI,such as service robots,cleaning robots,entertainment robots,medical surgical robots,and rehabilitation robots,are in demand.The early research of these robots is mainly concentrated in developed regions such as the United States,Europe,and Japan,China's investment in robots for human-computer interaction is relatively small,and our research path is very long.Facing the development needs of our country “Made in China 2025” and “Chinese dream”,HRI robots for various fields will have more and more use value.Therefore,research and development of flexible interactive robots with independent intellectual property rights and core competitiveness has great and farreaching significance.Compared with traditional industrial robots,supple interactivity and safety play an important role in the research of new robots.To achieve this goal,the research and design of compliant drives is becoming more and more important.This paper compares the design methods and performance advantages of the compliant drive at home and abroad,starting from the load-selecting stiffness mechanism of the universal interaction law "small load,low stiffness,large load,high stiffness",design the LDNSA which is applied to a 3-DOF compliant robot.For the designed LDNSA,the actuator step and sinusoidal response experiments were carried out to analyze the control performance of LDNSA.The optimization of the trajectory tracking control of the compliant robot with a nonlinear stiffness driver is mainly divided into two parts.Firstly,the robot system relies too much on sensor data acquisition,and the accuracy of sensor data acquisition is susceptible to external influences,which affects the accuracy of the end output.This paper uses the PD controller based on EKF state observer to solve.Secondly,in view of the problem of driver torque loss caused by the deformation of the original part and the variation of the small moment of inertia,the TSM control is used to solve the problem,and the stability based on Lyapunov and the robustness of the system under interference are analyzed.Through the optimization of the above two aspects,the compliant robot with nonlinear stiffness drive achieves accurate position output,which lays a good foundation for the development of subsequent compliant robot functions.