Research On Key Theories And Applications Of SMA Spring Actuated Jointless Hand Exoskeletion

With the aging of the population,the incidence of stroke increases year by year,and the postoperative complications such as dysfunction of the hand movement and even the absence of function have seriously affected people’s normal life.The traditional treatment is one-on-one treatment by medical staff,through a large number of repetitive training to restore and improve the patient’s hand motor function,this way of rehabilitation is not only high cost,low efficiency,and the rehabilitation effect is difficult to guarantee.With the continuous development of science and technology,researchers began to apply robotics to the field of rehabilitation medicine to assist patients in rehabilitation training.Hand exoskeleton as an important branch of rehabilitation robot,the main task is to assist the patient’s hand joints and fingers to complete the bending stretch of rehabilitation training.Based on the analysis of the research status at home and abroad,this paper designs a shape-memory alloy spring-driven hand rehabilitation exoskeleton and studies its key technologies.The main contents include:(1)Hand exoskeleton structure design.Based on the theoretical analysis of the physiological structure of the hand and the law of joint movement,the overall structure of the hand exoskeleton is designed,including the configuration of the degree of freedom,the selection of the driving scheme and the design of the joint mechanism.According to the mathematical model of one-way coupling line transmission,the arrangement parameters of the coupling cable of the designed exoskeleton structure are determined,which makes the exoskeleton movement more in line with the movement rule of the real manpower.(2)Kinematics and mechanics analysis of hand exoskeleton.Kinematics and statics analysis of healthy people as a basis for exercise control of exoskeleton.Then according to the structure of the exoskeleton designed by the subject,the kinematics of the exoskeleton is analyzed,and the mathematical model between the change of the main cable and the joint angle of the exoskeleton is established.Finally,the relationship between the cable force and the fingertip force in the grip state is analyzed,and the mathematical model between the two is established.(3)SMA Spring Modeling and Characterization Experiments.Based on the constitutive model of shape memory alloy,the mechanical model of SMA spring is established based on the design theory of common spring,and the required parameters of the model are measured through a series of experiments.Finally,the shape memory alloy spring was simulated by MATLAB software in the phase of austenite phase transformation to verify the correctness of the mechanical model and experimental parameters.(4)Development and experimental study of hand exoskeleton prototype.The control system of the hand exoskeleton is designed as a whole.Prototype and experimental platform of the hand exoskeleton are developed.The hand exoskeleton prototype is experimentally studied to verify the rationality of hand exoskeleton structure design and the correctness of kinematics model and mechanics model.