Structure Analysis And Load-bearing Mechanism Research Of Asymmetric Lower Limb Exoskeleton Robot

With the continuous development of science and technology,lower limb amputation patients are increasingly eager to work and live like healthy people.However,intelligent artificial limb is mainly passive/semi-active,which can only assist the normal walking of lower limb amputation patients and cannot meet their load-bearing needs of daily life.The lower limb load-bearing exoskeleton robot is a device that is worn on human body to assist human to withstand the load and provide assistance for the human body at any time.At present,the lower limb exoskeleton robot is mainly used in healthy people.There is no research on exoskeleton robots used in amputation patients.The asymmetric lower limb exoskeleton robot proposed in this thesis is a new type of exoskeleton robot for patients with upper knee amputation combined with intelligent artificial limb technology.Because of the complexity of its structure and the particularity of its users,we need to focus on the safety and reliability and the load-bearing effect of the exoskeleton.The main contents include:(1)Based on the finite element analysis method,the structural strength of each component of the exoskeleton is studied by structural static analysis,and the structural safety factor is checked.The modal analysis is used to study the virbration mode and natural frequency of each component of the exoskeleton,obtaining its overall stiffness.Analysis of the safety and reliability of exoskeleton robots based on the strength and stiffness of the exoskeleton structure and the amount of deformation of the exoskeleton.(2)The dynamic model of the lower limb support period was established,and the working mechanism of the lower limbs under the load-bearing state was analyzed from the perspective of energy and dynamics.Based on the working mechanism of human lower limbs under the load-bearing state,the coupled dynamics equations of asymmetric lower limb exoskeleton are established.Study the assistance mode of asymmetric lower limb exoskeleton robot,and the main factors affecting exoskeleton boosting effect in human-machine coupling movement.(3)Combining the existing structure of asymmetric lower limb exoskeleton robot,the closed-chain model of human-machine restraint system is established.Through the calculation of the degree of freedom of spatial closed-chain mechanism,the motion compatibility of human-machine closed-chain model is analyzed,and the human-machine constraint model is optimized.A flexible human-machine coupled kinematic chain is designed,reduce the influence of man-machine pose deviation on human-machine coordination movement.Analyze and calculate the binding force of the strap-type human-machine coupling mechanism and the binding torque generated by the binding force in the lower limb joint of the human body.(4)Aiming at the structural characteristics of asymmetric lower limb exoskeleton robot,a new flexible human-machine connection mechanism is designed.The mechanical force equation is used to solve the binding force of the flexible human-machine restraint mechanism and the binding torque generated by the binding force in the lower limb joint.Compared with strap-type human-machine restraint system,analysze the effectiveness of flexible human-machine connection mechanism to reduce human-machine binding force.Finally,the performance of the asymmetric lower limb exoskeleton robot is evaluated comprehensively from the perspectives of structural safety and reliability,load assist effect and wearing comfort.