Research On Intelligent Prosthetic Socket With Biomechanical Compatibility

With the increasing number of accidents in traffic and work environment,the total number of patients with physical disabilities is also increasing year by year.The most common way for patients with physical disabilities to return to society and fulfill the compensation of motor function is to wear a prosthetic limb.As the interface between the prosthesis and the stump,the design of the receiving socket directly affects the realization of the function of the prosthesis and the choice of whether the patient can continue to use it.However,although the existing design of the prosthetic socket has paid attention to the problems of human physiology and anatomy,it is only a conceptual design without specific design for the biological characteristics of human forearm soft tissue.Therefore,it is of great significance to develop a prosthetic socket with biomechanical compatibility.As a part of the national key research and development plan project "Intelligent Upper Limb Prosthesis with Bidirectional Neural Pathway"(project number:2018YFB1307200),the following work has been carried out in this paper:In this paper,the existing socket technology and the advantages and disadvantages are analyzed and summarized,combined with the artificial limb socket use requirements,explicitly socket need to implement "firm" "soft" switch function,choose a form for acceptance of socket,modular unit modular variable stiffness by design units and adapt to a variety of combination plan to accept the biomechanical compatibility of socket.Firstly,the modular variable stiffness element is designed.Through the institutional design and configuration options,select variable stiffness spring combinations to achieve modular structure,according to the design index of the unit and the application environment,select a brush motor to drive,and USES the cord for transmission,the design variable stiffness unit structure and the potentiometer,unit configuration to accept socket with functions of location-aware.Then,based on the anatomical and physiological characteristics of the human forearm,the biomechanical experiments of the human forearm were carried out to measure the compression pain threshold(applying pressure and depth of compression)and the stiffness curve of the human forearm.The correlation analysis of the experimental data was conducted to determine the correlation between the gender,the morphological size of the left and right arms and the forearm and the forearm pain threshold.According to the data of pain threshold,the affected area of the forearm of the variable stiffness element in the socket was selected and the variation range of the variable stiffness element in different affected area was determined.According to the stiffness curve of the forearm soft tissue,the variation range of the output stiffness of the variable stiffness element was determined.Then the variable stiffness element combination scheme is designed.Firstly,according to the anatomical characteristics of human forearm,the forces of different combinations of variable stiffness elements were analyzed,and the number of variable stiffness elements in the receiving socket was selected according to the principle of force balance and state switching.Then according to the condition of the patient’s stump,the design of short stump and long stump socket frame and unit combination scheme;Combined with the mechanical indexes obtained from the forearm biomechanics experiment,the state of the variable stiffness element was defined according to the output stiffness,and the element combination scheme suitable for different situations was designed.Finally,experimental tests were carried out to verify the results.Structures,test platform,the first output stiffness characteristics of variable stiffness unit measurement and verification,for hardware and software structures,to accept the whole socket after test,the test socket in the time needed for switching between different states and accept socket under different condition of force and motion transmission precision and the effect of prosthesis to socket through the data analysis to evaluate the overall effect.