Design And Performance Analysis Of Hybrid ALS Cervical Spine Exoskeleton Assist Mechanism

The cervical spine supports the human head,while the neck muscles provide traction for the head.For people with ALS,the atrophy of the neck muscles prevents them from turning and lifting the head like normal people.Indelible impact on the patient’s body and mind.In this paper,aiming at the loss of neck function of ALS patients,based on the pathogenesis and treatment plan of ALS at home and abroad,according to the motion mechanism of cervical vertebra,combined with the joint composition of cervical vertebra,an ALS cervical exoskeleton assist mechanism based on(2-PUR/UPS)&R mixed linkage mechanism is designed,which is mainly used to realize the multi-angle rotation of the patient’s head.To meet the use requirements of neck function in patients’ daily life.Firstly,a simple model of the mechanism was established,and the degree of freedom of2-PUR-UPS of ALS cervical spine exoskeleton assisted mechanism was obtained as 3 by using screw theory analysis,and the calculated degree of freedom was verified by the modified K-G formula.The exoskeleton can achieve multi-angle and all-round traction of the patient’s neck(flexion and extension,left-right flexion and left-right rotation).The closed-loop vector method was used to solve the position inverse solution of 2-PUR/UPS of ALS cervical exoskeleton booster mechanism.Particle swarm optimization(PSO)was used to solve the positive position of the mechanism,and the optimum fitness curve was obtained by Matlab software.On the basis of inverse position solution,Matlab software was used to analyze the working space of the mechanism.The first and second order influence coefficients of the mechanism were obtained by differential method,and the velocity,acceleration and dexterity of the mechanism were analyzed.The results show that the mechanism has good performance.Secondly,virtual prototype of ALS cervical vertebra exoskeleton was established in Adams simulation software,and the model was verified.Through the quality of the virtual prototype,initial velocity,initial setting,such as driving virtual prototype proneness after stretch traction,left and right side of the song,left-right rotating traction and vertical traction is kinematics simulation,measured ALS cervical vertebra displacement of the mass center of moving platform exoskeleton,center of mass velocity and barycenter acceleration curve along with the change of time,The results show that the exoskeleton can realize the rotation and upright function of normal human neck.The inverse kinematics simulation of the angular traction of the prototype was carried out.By setting the rotation Angle,the variation rule of the driving rod length was obtained,and the size of the power mechanism was optimized.Finally,the dynamics analysis of ALS cervical exoskeleton assisted mechanism.The Jacobian matrix of the mechanism force was obtained by means of the first-order and second-order influence coefficients obtained above,and the mapping relationship between the driving force and the output force was obtained.The static equilibrium analysis was carried out by the virtual work principle.In the moving platform on the organization’s and each of the branched chain after stress analysis,using the method of Lagrange and dynamics modeling based on the influence coefficient method and get the pose parameters of the moving platform based on dynamic model,and through the analysis of the Adams cervical exoskeleton steering mechanism in human head initiative role in driving force change curves.