| Since the 1960s,the research on exoskeleton technology has been carried out at home and abroad,and it is still a research hotspot at home and abroad.The term "exoskeleton" comes from the biological exoskeleton,which provides protection and support for shell-like creatures such as turtles and crabs.Inspired by biological exoskeletons,exoskeletons are designed to improve individual combat ability and protect the joints and ligaments of workers who perform long-term repetitive or weight-bearing tasks.When doctors resuscitate a patient,the exoskeleton helps the patient to meet the pressure required for strength in ample time.Exoskeletons could also increase the likelihood of outdoor travel and increase resistance to risk.Therefore,the application field of exoskeleton technology covers a wide range,including aviation,military,engineering,medical and health fields.Taking the upper extremity exoskeleton as the research object,this thesis develops from its kinematics,mechanical structure design,dynamics and joint position tracking control.The relationship between the four is progressive and content-coupled.Firstly,kinematic modeling of upper extremity exoskeleton is carried out in this thesis.The upper extremity exoskeleton is modeled as a rigid two-link based on the anatomical analysis of the physiological structure of the upper limb.Kin ematic modeling includes spatial coordinate rotation,homogenous transformation matrix of rigid motion,establishment of connecting rod coordinate system,D-H(Denavit-Hartenberg)and MD-H(Modifed-Denavit-Hartenberg)modeling methods,as well as calculation implementation based on MATALAB,and modeling of diff erent postures of shoulder joint and elbow joint of upper extremity exoskeleton.Secondly,in terms of kinematic modeling results,the upper extremity exos keleton is dynamically modeled in this thesis.The derivative of the homogeneous transformation matrix of the exoskeleton of the upper extremity is obtained acc ording to the properties of the antisymmetric matrix,and the Jacobian matrix of the upper extremity exoskeleton is obtained.In combination with the Euler-Lagra nge equation of motion,the dynamic modeling of the upper extremity exoskeleto n is completed,and the dynamic simulation of the single-arm mechanical structur e is carried out in ADAMS.Finally,in terms of dynamic modeling results,motion control simulation of the upper extremity exoskeleton was carried out in this thesis.Trajectory tracking control of the shoulder joint from 26° to 61° and the elbow joint from 20° to 49° was completed in this thesis.Combined with the actual mechanical structure of the upper extremity exoskeleton,some mass properties of the connecting rod,such as inertia,were not known,so the upper extremity exoskeleton was controlled by robust adaptive PD control.In order to solve the problem that the error increases with the increase of the motion period in the robust adaptive PD control,the adaptive robust iterative learning method is further proposed to reduce the tracking error of the shoulder and elbow of the upper extremity exoskeleton by increasing the number of iterations. |
