Design And Research Of A Lower Limb Climbing Exoskeleton Robot

The lower extremity exoskeleton robot is a device that assists the human body to perform synchronous movements.The device can assist elderly people or patients to complete independent walking and rehabilitation exercises.In daily life,ascending and descending stairs is an indispensable part.To this end,for the elderly and some patients with lower limbs to move upstairs,this article designs a lower limb climbing exoskeleton robot,from the kinematics and dynamic characteristics,Analysis and research on gait cycle planning,stability assessment,motion control,etc.First,according to the movement form and range of human joints,the lower extremity climbing exoskeleton robot is designed,and the movement process of its execution structure is analyzed.In order to facilitate analysis and data calculation,the exoskeleton robot is simplified,and the corresponding D-H model is established.The spatial analytic geometry method and the vector method are used to derive the positive kinematics and inverse kinematics respectively,and the relationship between the joint rotation angle and the end position.According to the Lagrangian dynamics equation,the corresponding exoskeleton robot dynamics model is established,and the expressions of the moments of the joints of the lower limbs are obtained through analysis and deduction.Secondly,according to the cycle of the lower extremity exoskeleton going upstairs,the gait planning precautions are assumed,and the parameters of the robot's bar information and the height and width of the stairs are set.Based on the developed lower extremity exoskeleton robot-assisted human climbing strategy,the three-dimensional spline interpolation method was finally selected by analyzing and comparing the advantages and disadvantages of several trajectory planning methods.According to the special key points of the robot's starting,intermediate and stopping steps when going up the stairs,Interpolation are performed to obtain the upstairs motion trajectory of the lower limb joints.Thirdly,for the stability of the planned motion trajectory,the ZMP zero moment point is used to evaluate the stability of the lower extremity exoskeleton robot.According to the definition and concept of ZMP,the stability formula of the lower limbs was derived,and the stability area of the one-foot support and two-foot support of the robot required for stability was planned,and its stability margin was determined.Combining kinematics and the ZMP online adjustment formula,the planned trajectory is stably optimized,and converted into the motion angle of the lower joints by kinematics inverse equations.Finally,the motion control method of the lower extremity exoskeleton robot is studied,and a sliding mode control method of nonlinear disturbance observer is proposed.In order to prove the accuracy and stability of its trajectory tracking,a Lyapunov function was constructed for determination.At the same time,this method was also applied to the simulation of extremity exoskeleton robots using MATLAB software,and the results performed better.In order to further verify the applicability of the method,an operating platform for the lower extremity exoskeleton robot was set up,and the uploaded data was basically consistent with the expected trajectory,indicating that the method of trajectory tracking is effective.