| Flexible robotic arm has good bending characteristics and low weight,so it can achieve higher physical human-machine interaction safety in unstructured environment than rigid robotic arm.To meet the intrinsic safety requirements of physical humanmachine interaction in unstructured environment,a design scheme of notched variablesection flexible manipulator is proposed.Based on head impact safety standard,the structural design,kinematics analysis and contact dynamics analysis of notched variable-section flexible manipulator are completed.The details are as follows.To meet the intrinsic safety requirements of physical human-machine interaction in unstructured environment,a design scheme of notched flexible manipulator with variable cross-section is proposed.Based on the safety standard of head impact,the structural optimization design method of the notched variable cross-section flexible manipulator is established.Comparisons between numerical calculation and software simulation show that the notched variable cross-section flexible arm can effectively change the rigidity of the arm and improve the intrinsic safety of physical man-machine collision.With the optimized design of the flexible arm cut,the impact index HIC at the end position of the arm is reduced by 67% and the width is increased by 58%.Kinematic analysis of the notched variable cross-section flexible manipulator is completed based on Bernoulli-Euler equation.Kinematic analysis of the notched variable cross-section flexible manipulator is completed based on 3R pseudo-rigid body model method.Finite element simulation analysis and numerical calculation results by finite element software Abaqus and numerical calculation software MATLAB show that the maximum error of the end trajectory is 0.58%,which verifies the correctness and validity of the proposed kinematic algorithm.Dynamic modeling and analysis of the collision process between flexible manipulator and human body are studied.Based on 3R pseudo-rigid body model,the dynamic mathematical model of flexible arm is established,the dynamic response of notched variable-section flexible arm is analyzed,and the modal dynamic response of notched variable-section flexible arm is analyzed.The comparison between numerical calculation and CAE simulation shows that the proposed dynamic model can simulate the dynamic characteristics of the end of the notched variable-section flexible manipulator under periodic load.The simplified dynamic impact model and finite element impact model are analyzed,and the displacement,speed,acceleration and head damage coefficient of physical human-machine interaction crash system are obtained.The calculation results show that the head damage coefficient of physical humanmachine interaction is lower than the crash safety threshold. |
