Structure Design And Research Of Automatic Folding Electric Wheelchair

The advancement of science and technology and the improvement of medical standards have prolonged the life span of human beings,which has also caused the problem of population aging.On the other hand,tens of millions of people with lower limbs have been disabled due to various accidents.They have lost the ability to walk,and their lives are extremely inconvenient.At the same time,the intelligentization and electrification of products have greatly improved the lifestyles of these people.In order to provide the elderly and the disabled with a humanized transportation tool with simple structure,good stability and simple operation,in view of the large volume,complex folding and unsatisfactory effects of electric wheelchairs currently on the market,this article intends to develop a The electric wheelchair can be automatically folded and unfolded without disassembling any parts.The specific research work is as follows:（1）Analyze the structural characteristics of two mainstream manual folding and one automatic folding electric wheelchairs on the market,find out their advantages and disadvantages,and provide ideas for the structural design of electric wheelchairs.According to the design requirements of the automatic folding electric wheelchair project and the relevant national standards,the wheelchair is conceptually designed,and three automatic folding electric wheelchair structure schemes based on the plane hinge linkage mechanism are proposed.The feasibility and rationality of the three schemes are compared and analyzed,the final wheelchair structure design scheme is determined and comprehensively evaluated,and the structure diagram is drawn to provide a basis for subsequent analysis.（2）Based on the theory of ergonomics,combined with the measurement data of adult body size in my country and the relevant national standards for electric wheelchairs,the relevant dimensions of the wheelchair are designed,including seat height,seat width,seat depth,seat inclination,backrest height,backrest width,and backrest Dimensional parameters such as angle of inclination,height and spacing of armrests,height of pedals,front and rear wheel assemblies.The wheelchair mechanism is equivalently simplified and split into three rod groups.Based on the closed-loop vector method,the kinematics modeling of the three rod group mechanisms is carried out to solve the angular displacement,angular velocity,angular acceleration of each rod in the mechanism,and the velocity and acceleration of each joint point.Based on the size design of the wheelchair,the size of each member of the mechanism is calculated by Matlab programming,and the kinematics simulation results are obtained,and the change curve of the mechanism’s motion parameters is observed,and the kinematic characteristics of the mechanism during the folding process are analyzed to verify the rationality of the plan.Analyze the force of each member of the wheelchair mechanism in a static state,and establish a static balance equation to obtain the force and reaction force of each member.On the basis of kinematics analysis,dynamic static analysis of the wheelchair mechanism is carried out,the balance equations of force and moment are established,and the motion of the mechanism is discretized in the period,and the force analysis results of each kinematic pair at t（28）5 s are obtained.（3）Based on the basic size parameters of the wheelchair design,the Solidworks software is used to carry out specific structural modeling and three-dimensional modeling of the wheelchair components,complete the assembly of the wheelchair,and observe whether the components interfere in the folding process.The results show that the structure of the wheelchair is reasonable and there is no interference in the folding process.（4）The kinematics simulation of the virtual prototype of the wheelchair is carried out by using Adams software.The Angular Displacement,angular velocity,angular acceleration of every member and the velocity and acceleration of every joint in the folding process are measured,and the change curve is output.The maximum error of angular displacement is 8.4×10-3 rad,the maximum error of angular velocity is 12.09×10-4 rad/s,and the maximum error of angular acceleration is 2.02×10-3rad/s2,the maximum error of joint velocity is 2.6×10-4 m/s,and the maximum error of joint acceleration is 3.82×10-4 m/s2,which verifies the correctness of the kinematics model of the wheelchair mechanism.The finite element analysis of the key parts of the Automatic folding electric wheelchair is carried out based on Ansys.The results show that the structure strength and stiffness meet the design requirements.（5）The driving motor and electric push rod of automatic folding electric wheel chair are analyzed and selected.According to the design requirements of the project and the relevant national standards,the motion parameters of the electric wheelchairs were checked.The minimum radius of rotation of the wheelchair was 905 mm,the climbing ability was17.2°,and the limit roll Angle of the wheelchair was 25.1°.When the starting distance is0.5 m,the theoretical barrier height can exceed0.04 m.