Research On Sliding Mode Impedance Control Method For Upper Limb Exoskeleton

In this thesis,the research object is upper limb exoskeleton,the research goal is not only to make the upper limb exoskeleton can accurately track the movement of the upper limbs,but also make the wearer can exercise with upper limb exoskeleton safely,free and comfortably.In order to achieve the control requirements in this thesis,the movement of the upper limbs of the human body is firstly analyzed to obtain the basic form of motion of the upper limbs,which is the basis of the follow-up study;then the kinematics and dynamics of the upper limb exoskeleton are analyzed and the corresponding model are established in this thesis also;Then,according to the model established in this thesis,the sliding mode control method and the sliding mode impedance control method are analyzed respectively,under the upper limb exoskeleton model,the co-simulation of individual control methods are carried out,and the advantages and disadvantages of each method are analyzed.Combined with the actual control requirements,the control method that meets the control requirements of this subject is designed.(1)Firstly,the basic structure of the upper limbs of the human body is analyzed,and then the structure and the movement form of each joint are analyzed.In the actual design of the upper limb exoskeleton,the main principle is simply the model and the control method under the premise of meeting the control requirements,also make the control method easy to realize.In this paper,three degrees of freedom are selected for the shoulder joint,one degrees of freedom are selected for the elbow joint,a brief analysis of the shoulder and elbow joint movements is also performed.(2)The position of the end effector of upper limb exoskeleton is analyzed by D-H method,the mutual transformation between the coordinate system and the base coordinate system of the end effector is analyzed,and the corresponding coordinate transformation matrix is obtained in order to establishing the kinematic model of the upper limb exoskeleton.Based on the commonly used method of robot dynamics analysis(Lagrange method),the dynamic model of upper limb exoskeleton is established,and the driving torque required by each joint during the motion is obtained,also a prototype of the upper limb exoskeleton in ADAMS is established.(3)Based on the ADAMS dynamics model,The MATLAB-ADAMS joint simulation of the control method is realized in this thesis.By analyzing the sliding mode control method of upper limb exoskeleton,it can be known that although the sliding mode control method has better robustness and achieve a good tracking effect,however,it does not reflect the human-machine coupling of the exoskeleton.Then the human interaction model is analyzed,and a sliding mode impedance control method is proposed based on the sliding mode control.Under the premise of satisfying the man-machine coupling,the whole control system can be better robust.