Flexible Joint Design And Performance Analysis Of Robot Variable Stiffness

With the advancement of social science and technology and the development of industrial technology,the application of robots in social production and life has become more and more extensive.The demand for robots is slowly shifting from traditional industrial production to the service industry.The traditional robot joints used for industrial production are almost rigid joints.The robots are operated by various mechanical or mechanical parts.Their operations The accuracy is high,but the safety of the workers around the robot is not guaranteed.However,as service robots continue to flow into people's lives,there is an urgent need for robots to have variable stiffness characteristics,so that when the robot arm hits a person,the variable stiffness flexible joint inside the robot can absorb the external impact energy,thereby reducing Or avoid robot damage to people to achieve safe interaction between robots and people.Based on this application background,this paper designs a variable stiffness flexible robot joint used in the field of service robots.Different from the commonly used rigid joints,on the one hand,the flexible joints of variable stiffness can realize the flexible output of the articulated arm.In the environment of interaction with humans,the mechanical arm can absorb external energy when it touches people,and plays a buffering role.In order to avoid robot damage to people.On the other hand,the stiffness of the joint can be adjusted by the stiffness adjustment motor.In practical applications,we can use the artificial intelligence algorithm to make the joint stiffness automatically adjust online according to the environment used.The variable stiffness joint designed by this subject adjusts the joint stiffness through the built-in permanent magnet and the spring.Compared with the prior art,the mechanical structure is simpler and more compact,the adjustment efficiency is higher,and the response is more rapid.Based on many literature investigations and arguments,the paper designs the working principle of variable stiffness joints,and uses mechanical-magnetic coupling to realize the flexible output of joints and the change of joint stiffness.The flexible output of the joint is mainly realized by the spring group inside the joint.The adjustment of the joint stiffness is mainly realized by the contact area between the inner shell magnet and the inner shell magnet of the joint.The angular displacement and the angular velocity of the joint are controlled by the position control motor,and the axial movement of the magnet housing is controlled by the stiffness adjustment motor,thereby realizing the change of the contact area between the outer casing magnet and the inner casing magnet,so as to achieve the purpose of changing the joint stiffness.According to the principle of joint stiffness,the paper uses Solid Works to design the mechanical structure of the joint,and carries out specific design and analysis for the spring group.Then the ABAQUS software is used to analyze the joint statics,and the key of the joint is made by Fe-safe software.Fatigue analysis was performed on the stressed parts.For the magnetic field inside the joint,the selection of the magnet material and the theoretical calculation of the magnetic force were carried out.The arrangement of the internal magnet and the generated magnetic hysteresis were optimized by Maxwell software.The simulation results of the joint magnetic hysteresis were obtained..Finally,Adams software was used to analyze the joint dynamics,and the stiffness value of the joint,the impact force of the joint arm,the torque and the force of the spring were tested when the articulated arm hit the obstacle.According to the function of the joint to realize the requirements,the electronic control system of the joint was designed,and the electrical components such as the motor,the reducer and the sensor were selected.The electrical hardware structure diagram of the joint and the corresponding circuit diagram are designed,which lays a foundation for the subsequent test of the variable stiffness joint and its application on the robot.In addition,based on the sliding mode control method,the algorithm for suppressing joint buffeting is designed for the chattering phenomenon that joints may appear in actual motion.It is proved by MATLAB simulation that there is better buffeting suppression effect.