Research On The Design And Dynamic Characteristics Of The Metamorphic Lower Limb Exoskeleton Robot For The Elderly

In recent years,the senior citizen population in my country has been increasing with each passing year,and the trend of population aging will continue to intensify in the future.The happiness of life of the senior citizen is worthy of attention from every vocation,and products related to the improvement of their quality of life are gradually being valued.Helping the elderly with weak lower limbs when walking,improving the walking safety of the elderly,and improving the lower limb mobility of the elderly have been popular directions in the elderly robot field in recent years,However,most of the current robots for helping the elderly are relatively simple and expensive.Therefore,the elder-aiding robot with various functions and low cost has important practical significance for increasing the utilization rate of elderly-assisting robots and improving their quality of life.The metamorphic mechanism can change its topological structure due to the limiting structure of the mechanism itself and the special size of the rods in accordance with different working conditions,play a role in different working environments and meet the requirements of a variety of tasks.Therefore,applying the principle of metamorphic mechanism to the field of helping the elderly,and carrying out the design of metamorphic robots for helping the elderly and related research work meets the actual needs of the current helping elderly industry and has obvious social benefits.This article first analyzes the state of research on metamorphic robots and exoskeletons at home and abroad,Grasp the current deficiencies and development trends of research on robots for the elderly at home and abroad.Then analyzes the structure of the legs of adults and changes in the properties of the legs during walking,specifying the degree of freedom required for walking in the elderly.Combining graph theory knowledge and kinematic chain synthesis,an optimal configuration was selected based on functional requirements,conditions and configuration constraints,designed a metamorphic lower extremity exoskeleton robot configuration that can flexibly realize three different configurations of walking,sitting and squatting,and proposed the overall design of the exoskeleton robot,and compared each design in detail.The pros and cons of,the most reasonable design plan is selected.According to the D-H parameter method and the analytical method,the forward and inverse kinematics analysis of the first configuration of the model is conducted,and the forward and inverse solutions of the displacement equations of the knee joint,ankle joint and toe are obtained.The displacement equation is derived to obtain the knee,ankle and The velocity solution and acceleration solution of the toe.Use Matlab to obtain the expression of the angle change of the hip,knee,and ankle joints in one gait cycle,combine the relationship between the drive joint angle change and the kinematic parameters of the knee,ankle,and toe to perform kinematics numerical simulation.At the same time,use ADAMS The kinematics simulation of the metamorphic lower limb exoskeleton robot for the elderly is carried out to verify the validity of the numerical results of the Matlab kinematics.The simulation results show that the changes in the kinematic parameters of the lower limb joints in the walking posture conform to the law of human motion.The kinematics simulation lays the foundation for the working space analysis of the walking posture,the parameter design of the joint limit structure and the dynamic analysis.Next,the generalized coordinate system of the metamorphic lower exoskeleton robot in the first configuration in the single-leg support state is established,and the centroid position and centroid velocity expressions of each member are derived,and then calculated according to the position and velocity equations get the kinetic energy and potential energy of each rod.The Lagrange method was used to establish the dynamic equation,and the expression of the torque required by the hip and knee joints during the support period was obtained.The relationship between the angle changes of the hip and knee joints and the active joint torque can lay the foundation for the dynamic numerical simulation,and Provide assistance in the design of control system and drive system.Finally,the dynamics virtual simulation of the entire gait cycle of the exoskeleton robot is carried out.First,the man-machine model established in the 3D software is imported into ADAMS,the driving function,material properties and other parameters are added and the rods are constrained to establish the man-machine coupled walking dynamics model.Through dynamic virtual simulation,the dynamics of the hip and ankle joints of the exoskeleton robot's active joint driving torque changes in a gait cycle are intuitively revealed.The value range of hip joint and knee joint in a gait cycle is determined,which provides strong theoretical support for subsequent prototype production.