Analysis And Design Of Variable Stiffness Principle Of Joint Actuator Based On Permanent Magnetic Spring

Traditional industrial robot joints are mostly driven rigidly.Because the robot joint driver with rigid drive has the characteristics of high motion accuracy,strong load capacity,fast response speed,etc.,but the robot joint stiffness is single and does not have the ability to actively change the stiffness,so the robot may collide with some unforeseen obstacles in the work,causing failure or even damage,The safety of equipment and operators cannot be guaranteed,the safety of human-computer interaction is low,and the environmental adaptability is poor.With the rapid development of robot technology,robots are more widely used in daily production and life,and the working environment is more complex and changeable,which puts forward higher requirements for the flexibility,safety and environmental adaptability of robot joints.Flexible variable stiffness joints have large stiffness adjustment range,good cushioning performance and good environmental adaptability,which greatly improves the safety of human robot interaction.This paper takes the flexible variable stiffness joint driver as the research object,starts from the variable stiffness principle of the joint,and studies the variable stiffness structure inside the robot joint according to the characteristics of nonlinear stiffness changes of the permanent magnet spring when it works.The main research contents of this paper are as follows:1)After consulting relevant literature and analyzing the mechanical structure and principle of the existing variable stiffness flexible joint,the variable stiffness mode adopted in this paper is determined,that is,a variable stiffness joint driver structure based on permanent magnet spring is proposed.2)By analyzing the variable stiffness mechanism,a variable stiffness joint structure based on permanent magnetic spring is designed and the 3D modeling of the joint is completed;According to the principle of variable stiffness,the mechanism is designed in detail and the key components are selected.3)The static analysis of main parts is carried out.According to the working principle of variable stiffness joints,the stiffness variation characteristics of variable stiffness joints and the mapping relationship between joint torsion angle and stiffness are calculated.4)The effect of variable stiffness is simulated and analyzed,and the stiffness variation curve of the joint and the variation range of the elastic force of the permanent magnet spring under the applied load are obtained.5)Through the structural static analysis of the main parts,the stress,strain and deformation of the main parts are calculated,and then compared with the allowable value of the corresponding materials of each part to determine whether the design requirements are met.6)The experiment platform of variable stiffness mechanism was built to verify the feasibility of variable stiffness joint driver.