The Research On Bionic ARM Based On Series Elastic Actuator

In recent years,with the expansion of robot application fields and the diversity of work tasks,traditional robots are difficult to achieve softening motion and safe human-machine interaction due to the large rigidity of the joint structure.Based on the series elastic actuator technology,this paper designs a three-degree-of-freedom bionic robot arm for the softening motion of the mechanical arm,which is based on the human arm muscle-tendon tissue form and motion mechanism.The flexible joints adopt an elastic drive transmission structure of an antagonistic spring combination with soft rope tensioning,which has human-machine interaction and impact resistance.The main contents of this paper are as follows:Firstly,a three-degree-of-freedom bionic robot arm with shoulder roll joint,shoulder pitch joint and elbow pitch joint is designed with reference to the human arm size and motion characteristics and a three-dimensional model is constructed by CATIA.The design scheme of flexible joint "reduction motor + elastic component + load" is proposed.According to the human muscle-tendon "Hill-Type" simplified model and the working principle of the arm antagonist muscle,an active spring-driven and passive spring-constrained antagonist spring combination is designed for the flexible joint to achieve the passive compliance of the joint.The selection and design of key components such as control board,geared motor and sensor are completed and an experimental prototype is built.Secondly,the simplified coordinate system of the three-degree-of-freedom bionic robot arm is established and the DH parameter table is determined.Through the matrix transformation,the pose matrix and the Jacobian matrix of the execution end of the manipulator are calculated.The kinematics modeling of the manipulator and the kinematics analysis of the bionic robot arm is completed.Then,the virtual prototype of the compliant mechanical arm is constructed in ADAMS and the spring parameter is selected by the control variable method to complete the stiffness design of the flexible joint.Based on the established virtual prototype,the simulation experiment of the bionic robot arm is carried out.By analyzing the joint position,angular velocity and angular acceleration curve,it is verified that the bionic robot arm has good adaptability to different forms of driving signals.Static and dynamic impact simulation experiments are carried out on the flexible joints to verify the impact resistance of the bionic robot arm joints.Finally,the control strategy of the bionic robot arm is determined and the experimental study on the three-degree-of-freedom bionic robot arm is experimentally studied with the experimental prototype platform.The human-machine push experiment is carried out on the smooth performance.The results show that the robot arm can achieve a certain degree of motion softening and maintain a safe interaction with human.Static and dynamic impact tests are carried out on the impact resistance of flexible joints.The results show that the antagonistic spring group of the joint can produce large flexible deformation when impacting at the output end of the joint,has the ability to absorb vibration quickly and has a certain protective effect on the internal structure of the joint.