Design And Experiment Of Finger Rehabilitation Device Driven Based On Non-circular Pulley And Five-bar Mechanism

At present,most finger rehabilitation mechanisms achieve the expected motion by scale synthesis or using multi-degree-of-freedom mechanisms,which cannot achieve the requirements of posture and trajectory for finger rehabilitation at the same time.In this paper,a single-degree-of-freedom non-circular pulley and five-bar finger rehabilitation mechanism is proposed to meet the requirements of finger motion through motion capture experiments,extracting four important poses and solving the solution domain of the five-bar mechanism with four exact poses based on the solution-region synthesis method,the non-circular pulley is used to constrain two links in the five-bar mechanism to make it a single-degree-of-freedom mechanism.According to the requirements of the finger rehabilitation mechanism and considering the force transmission characteristics of the mechanism,a mechanism parameter optimization model is established and the best parameters are optimized.The calculation model of non-circular pulley transmission is established,and the profile of non-circular pulley is solved according to the obtained turning angle relationship that needs to be satisfied by the finger joint.Based on the obtained parameters of the non-circular pulley and five-bar mechanism,the finger rehabilitation device was designed and developed in combination with the structural requirements of finger rehabilitation,and experimental studies were conducted.The main contents of this paper are as follows:1)The structure and motion form of the finger were analyzed,and the data acquisition experiment of finger flexion and extension motion was carried out based on NOKOV Motion Capture System.The test data were processed to obtain scatter diagrams of the fingertip trajectory in standard form and joint turning angle diagrams with uniform scatter distribution,respectively,to provide a parametric basis for the subsequent mechanism design.2)A single degree-of-freedom non-circular pulley and five-bar mechanism for finger rehabilitation and its integrated design method are proposed for the finger flexion and extension motion requirements.Four important poses on the fingertip trajectory are extracted,and the solution domain of the five-bar mechanism through four exact poses is solved by using the solution-region synthesis method;a joint force analysis model is established,and a force transfer performance index is introduced to preferred the solution domain and achieve the optimization of the mechanism parameters.A calculation model of non-circular pulley transmission was established,the profile of pulley was solved according to the corner relationship between the finger joints,and the design of the non-circular pulley mechanism was improved according to the rehabilitation motion requirements.3)The structural design of the finger rehabilitation device was carried out,the 3D model was drawn using Solid Works software,the main parts of the prototype were processed using 3D printing technology,and the assembly of the prototype rehabilitation device was completed.The digital servo model was determined according to the safety torque of the finger joint,and the control of the servo angle and speed was realized through PWM technology,and the design of the drive module was completed.The pose verification experiment of the finger rehabilitation device was carried out,comparing the actual trajectory of the fingertip with the ideal trajectory,as well as the actual and ideal parameters at the four poses to verify the correctness and feasibility of the finger rehabilitation mechanism design;the finger surface pressure experiment was completed to verify the safety and reliability of the finger rehabilitation device.