Biomechanical Simulation Of Human And A Soft Robotic Arm Interaction:Imitating Taiji Pushing Hands

Nowadays safe and confortable human-robot interaction-HRI has become one of the important problems in the field of service robot and has aroused general interests.Aiming at researching the soft robotic arm's HRI issue,the biomechanical measurement and analysis is conducted on the basic form of Taiji pushing hands which has the compliant interaction feature,and the biomechanical simulation of tester performing Taiji push-hand movement alone is conducted.Besides,the kinematic model of tester's right upper limbs is established and and the kinematics of human's upper arm during Taiji pushing hands is analyzed.Besides,the human-soft robotic arm co-exsiting model is builded in LifeMOD software and the the biomechanical simulation of human and a soft robotic arm interaction which intimates Taiji pushing hands is achieved.Main contents and achievement of this paper are as follows:The biomechanical measurement experiment on the basic motion of the Taiji push-hand which is called fixed-step push-hand using single hand is carried out through FAB motion capture system and MYO armband.The results of this measurement which consists of kinematic data,the foot pressure data and the surface electromyography data of the right forearm muscles are processed and analysed.Using the LifeMOD biomechanical modeling and simulation software,the virtual body model of the tester is established,including 19 basic segments,18 joints and 118 soft tissues.The motion captured data are processed,transformed and imported into the human body model in LifeMOD.Then the biomechanical simulation of the human model performing the Taiji fixed-step pushing hands alone is carried out,and through the simulation,kinematic data of segments,joint torque,muscle contracts and muscle forces of the human model are acquired and analysed.Through robotics theory,the kinematic model of the human right upper limbs is established,which includes six degrees of freedom:flexion/extension and abduction/adduction of shoulder joint,flexion/extension and spinning insides/outsides of elbow joint,flexion/extension and abduction/adduction of wrist joint.The posterior coordinate system of the model is established through the D-H method and the positive kinematic solution of the palm is obtained through the coordinate transformation.The reciprocal workspace of the palm is determined by the traversal algorithm.Through the differential varying method the Jacobian matrix of the kinematic model is solved and the flexibility of the right upper limb model during the Taiji push-hand is analyzed with the manipulability as evaluation index.The virtual model of 6-DOF soft robotic arm is established in ADAMS and the compliance is achieved by adding torso spring-dampers to each joints.The human-soft robotic arm co-exisiting model is acquired in LifeMOD.Besides,the human-soft robtic arm interaction's simulation while human playing the active role is achieved,so as the human-soft robotic arm interaction's simulation:intimating the Taiji pushing hands.Through comparing the joint torques of the human alone Taiji push-hand simulation and of the simulation of human-soft robotic arm interaction of Taiji pushing hands(which is referred to as Taiji push-hand HRI simulation),conclusion is drawn that the joint stiffness of human body can vary depending on the affected load.Besides,this paper conducts the different soft robotic arms which had five different joint stiffnesses performing Taiji push-hand HRI simulation.Then analyzing the contact forces of these five HRI simulations,and conclusion is drawn that lower joint stiffness of soft robotic arms can lead to lower contact forces,thus improving the safety of the physical human-robot interaction.