Structure Design And Analysis Of Intelligent Wheelchair Auxiliary Standing For Patients With Lower Limb Dysfunction

With the intensification of the population aging process and the increasing number of patients with lower limb dysfunction caused by diseases and other factors,the nursing pressure of rehabilitation institutions,nursing institutions and family members has increased.It is a social need to solve the life problems of patients with lower limb dysfunction and improve their happiness in life.In response to the patient’s needs for posture transformation and comfort,this paper designs a intelligent wheelchair with auxiliary standing function.The auxiliary standing mechanism adopts the form of the exoskeleton of the lower limbs,and it takes 21 s to complete the stand-up action.The saddle-shaped support seat is designed in the crotch to reduce the interaction force of the human-machine contact when the patient is in a standing posture to improve the comfort of the patient.First of all,according to the physiological knowledge of human lower limb anatomy,determine the freedom of movement of the lower limb joints and the corresponding physiological range.Determine the sitting and standing state of the human body according to the sitting posture theory.According to the standing process of the human body,for the purpose of reducing the driving torque of the joints,preliminary motion planning of the human standing process is carried out.According to the inertial parameters of the human body,the calculation of the human body center of mass and the static torque of the joints is given formula.Secondly,according to the relevant design requirements of Ergonomics,the structure design of the intelligent wheelchair is carried out according to the national standard of electric wheelchair.The chassis is designed for the purpose of preventing the wheelchair from toppling during operation,and the form of the lower extremity exoskeleton is used as the basis for the design of the auxiliary standing mechanism for the purpose of streamlining the mechanism.This form makes the human-machine coordination better.The non-linear optimization method is used to optimize the design of the drive system of the auxiliary standing mechanism,so that the stroke and the installation position of the linear actuator are coordinated with each other.The installation of the drive system considers the size adjustability of the mechanism.Even if the relevant dimensions are adjusted in order to match the mechanism with the user,the drive system can still work normally.A three-dimensional model of the intelligent wheelchair was established using Solid Works,and its corresponding performance parameters were calculated.Then,the kinematics modeling of the wheelchair chassis was carried out to establish a connection between the rotational velocity of the driving wheel and the motion state of the wheelchair.The relationship between the kinematic parameters of the joint and the linear actuator is deduced,and the motion planning for the standing process is carried out for the purpose of reducing the impact.The kinematics model of the auxiliary standing mechanism is established,and the coordinate change of the rotation center of the hip joint during the standing process is calculated.Newton-Euler equations are used to establish a dynamic model of the auxiliary standing mechanism.The velocity and acceleration parameters of each component are derived from the forward direction,and the driving torque of each joint and the thrust required by the linear actuator are derived from the reverse direction,and Matlab is used for theoretical calculations.Finally,the human body model is established based on the corresponding parameters of the human body,and Adams is used to simulate and analyze the coupling model of the human body and the auxiliary standing mechanism.The comparison between the simulation results and the theoretical calculation results verifies the correctness of the model established in this paper.Use Simulation to analyze the static strength of the auxiliary standing mechanism,check the strength of each key component,and verify the safety of the intelligent wheelchair structure.Therefore,the auxiliary standing intelligent wheelchair designed in this paper satisfies the design requirements in terms of manmachine coordination,safety,and functionality.