Research On Implementation Method Of Robotic Joint Stiffness Based On Magnetorheological Principle

At present,intelligent robot technology is more and more involved in people's work and life.This requires robots to adapt to different working environments and require higher safety during movement.Currently,most of the research on robots is based on traditional rigid The robotic arm is implemented with high-precision sensors and advanced control algorithms,and it has not yet met the current working requirements of the robot in different environments.Therefore,it is of great theoretical significance and application value to develop a variable stiffness robot joint that can adapt to a variety of different working environments.Aiming at the above requirements,a method for realizing the variable stiffness of robot joints based on the principle of magnetorheological is proposed.The main tasks completed are as follows:Firstly,a joint variable stiffness actuator consisting of a rotary magnetorheological damper,a servo motor,and a planetary reducer is proposed.The overall structure of the variable stiffness actuator and the variable stiffness robot joint is studied and designed.The auxiliary force required by the robot joint is analyzed and calculated,and the theoretical parameters are provided for the design and calculation of the damper.Secondly,in order to solve the leakage problem of the magnetorheological fluid in the magnetorheological damper,a magnetorheological fluid sealing device was designed and its sealing characteristics were experimentally studied.Based on this,a new type of rotary magnetorheological damper with a T-shaped rotor is designed.Based on the performance parameters of the magnetorheological fluid and the preliminary configuration of the damper,the magnetic circuit design of the damper was completed.In order to make the joint structure more compact,the damper was optimized and designed without affecting the mechanical properties of the damper,and the structural parameters of each part of the damper were obtained.The finite element analysis method is used to simulate and analyze the mechanical properties of the damper,and to support the theoretical calculation.Thirdly,the acquisition and control system of the variable stiffness robot joint is designed.A static torque sensor was used to obtain the joint torque of the robot in real time,and a closed-loop control system was established with the joint torque as feedback information.The fuzzy PID algorithm was used as the control algorithm of the system.A photoelectric encoder is used to collect the joint movement position and movement speed in real time,and use this to determine the joint movement state.The expected value of the control system is obtained through theoretical calculation.Finally,a test bed for testing the sealing characteristics of the magnetorheological fluid dynamic sealing device and a test bed for the mechanical performance of the variable rigidity actuator were established to verify the sealing characteristics of the designed dynamic sealing device and obtain the mechanical performance parameters of the variable rigidity actuator.Then,a variable stiffness robot joint test platform was established,and the fixed stiffness experiments and adaptive stiffness adjustment experiments of the robot joints were completed.The experimental results verified the feasibility of the proposed method for variable stiffness of robot joints.