Design And Study Of Flexible Manipulator Joints With Variable Stiffness

In recent years,with the continuous improvement of robot technology,the application field of robots is more and more wide,and robots has gradually penetrated into the fields of service and family from the traditional industrial field.In these areas,the interaction between robots and people is more and more frequent,and the working environment of robots is diverse,complex and changeable,which puts forward more stringent requirements for the performance of robots.Flexible variable stiffness joint has a better environmental adaptation,high load weight ratio and good buffering performance.It can not only improve the safety performance of human-computer interaction,but also improve the utilization of energy.Attracting more and more attention from scholars,research on flexible variable stiffness joint is becoming hot on robotics gradually.In this thesis,a flexible variable stiffness manipulator joint was designed based on the principle of joint variable stiffness,and the following works were carried out:(1)The mechanical structure of variable stiffness joint was designed.First,the design parameters of the joint were determined,a principle of variable stiffness based on leaf spring and spring was proposed and the stiffness of the joint was calculated theoretically.The intermediate transmission mechanism was analysis,including the selection of parts,a detailed analysis of the key components of the design,the final 3D model drawing joint.Finally,the range of stiffness of joints was analyzed on the theoretical perspective.(2)A dynamic model of joint was established.Because of the variable stiffness joint series elastic actuator has a certain similarity,therefore,the commonly used dynamic model of series elastic actuator was summarized;Considering the factors of joint modeling deeply,a relatively perfect joint dynamic model of variable stiffness was established and dynamic characteristics of the joint was analyzed by Simulink simulation.The simulation results showed that the response time and bandwidth of joint changes with different stiffness.(3)Using the simulation ability of Adams,simulation test platform of flexible variable stiffness joint was established;through the static stiffness simulation test,the variability of joint stiffness and correctness of variable range of stiffness was verified;through the joint step test and the sinusoidal position following test,the relative rationality of the variable stiffness joint dynamic model was verified.Finally,the character of safety and energy storage of the flexible variable stiffness joints was simulated and analyzed in detail,The differences of the safety and energy storage between the traditional rigid joints and flexible variable stiffness joints with elastic mechanisms were compared.The design of flexible variable stiffness joint mechanical structure,dynamic model and simulation method can provide theoretical basis and reference value for subsequent optimization design and simulation verification.