Research On Compliance Control Of Flexible Joints Based On Series Elastic Actuators

Taking into account the characteristics of robotic arms commonly used in the industry,the current robotic arms not only need to have precise trajectory movements,but also need to achieve more contact tasks on this basis.The end of the robotic arm not only needs to move according to the specified trajectory,but also needs to allow the end of the robotic arm to smoothly capture the target object.Combining the existing conditions and industrial needs,the series elastic actuator(SEA)is introduced as a part of the flexible joint of the robot arm,which can better enable the robot arm to interact with the environment.This article will also design a SEA and design the structure of the flexible joint of the robotic arm based on this SEA,and perform the following analysis work on the flexible joint:First,use the modular idea to make the overall design of the flexible joint.On this basis,a new type of corrugated elastic element is designed as the flexible part inside the joint.Using the method of optimized analysis and design,the relatively most reasonable corrugated elasticity is designed.By comparing with the other two SEAs,the advantages of choosing corrugated SEA are obtained.Due to the good stiffness characteristics of corrugated SEA,SEA is introduced into the joints of the robotic arm,and optimized on the basis of the Spong simple joint model,considering the impact of SEA damping and introducing electrical damping,which makes the dynamic model of flexible joints It has been optimized and analyzed that different SEA parameters will have different effects on the flexible joint system.After that,the model of the flexible joint was simplified,and the virtual prototype of the flexible joint was established using ADAMS software.The parameters of the virtual prototype were set and then combined with Simulink.The PID controller was used to simulate and analyze the torque control and position control.Based on PID control,and considering the contact and interaction with the environment,an impedance controller is introduced to simulate the output control of the end position of the flexible joint under the interference of the external environment,and analyze the change of each impedance parameter to the joint output The influence of changes in shaft position and contact force.Considering that the environment is not static,a fuzzy controller is introduced on the basis of closed-loop PID control and impedance control,and then the flexible joint system is processed with fuzzy,fuzzy inference,and clarification.The simulation analysis is flexible after the fuzzy control is added.The change in the output of the joint system proves that the fuzzy control is very helpful to improve the output effect of the flexible joint.Set up an experimental platform for flexible joints,process three corrugated elastic elements with different thicknesses,and conduct stiffness calibration experiments on three corrugated elastic elements with different stiffnesses,compare with the previous elastic element mechanical performance analysis,and then analyze the source of error.Three kinds of elastic elements with different stiffness are introduced into the joints to provide flexibility for the joints.The flexible joint experiment platform is used to perform the position following experiment of the end of the output shaft of the flexible joint to verify that the designed corrugated elastic element can realize the design in this paper.Ideal position control under indicators.After verifying that the effects of the three elastic elements with different stiffness and the end load on the output position are consistent with the previous simulation analysis.