Exoskeleton Man-Machine Interaction And Manipulator Compliance Assembly Using Force Control

Restricted by technologies such as perception and control,as well as by the unstructured environment of the industrial site,it is still difficult for current industrial manipulators to quickly realize fully autonomous planning and obstacle avoidance functions in such industrial environment.In response to the challenges faced by the manipulators in the unstructured industrial environment,the industrial manipulator is guided to the target position through the joint teaching of man and another robot,and then the industrial manipulator should complete the assembly task independently.This thesis takes the assembly problem in the unstructured industrial scene as the background,studies the interaction between human and collaborative exoskeleton and the control problem in the interactive process,how to realize stable human-robot interactive teaching movement,and after the teaching movement,how the industrial manipulator can independently realize the problem of 'compliant assembly' with force/torque sensor in its end.This thesis focuses on the above-mentioned issues and does the following work:(1)A force-controlled cooperative exoskeleton robot based on a series elastic actuator is built.The structure of the plane torsion spring type series elastic actuator is analyzed,and the active compliant joint based on the series elastic actuator is designed.The analytical form of the exoskeleton forward and inverse kinematics is analyzed,and the mechanical model of the cooperative exoskeleton is constructed.Experiments show that active compliant joints have good and stable mechanical properties,which can meet the needs of human-computer interaction.(2)Compliant control of the contact force/torque between the exoskeleton and the user is achieved.A basic torque controller based on motor speed is designed to control the torque output of active joints,and a position controller based on torque controller is designed on the basis to ensure that the joints can accurately move to the target position.Two interactive modes between user and exoskeleton are analyzed,and compliant teaching control in the joint space of the collaborative exoskeleton is realized.Experiments show that the above-mentioned controller can quickly respond to the human-machine interaction torque,the steady-state of torque error is less than 0.3%,the trajectory tracking error is less than 0.5 degree,and the human-machine contact torque during the teaching process is maintained within the range of less than 0.5Nm.(3)For industrial assembly problems,the workpiece-hole deviation model is established to realize autonomous and compliant assembly.A speed-based admittance controller is designed to realize the compliant control of the contact force,and the posture adjustment stage and the hole search stage in the assembly process are modeled and analyzed.The analytical form of the position deviation and the angle deviation is given.Experiments show that the angle deviation model error is less than 3°,and the interaction force between the workpiece and the shaft hole during the entire assembly process is less than 2N,and the assembly task can be successfully completed.