Design And Development Of A Wheelchair-exoskeleton Hybrid Robot For Lower Limb Motion Assistance

As a traditional sports auxiliary equipment,wheelchair can assist patients with lower extremity motor dysfunction to move for a long distance,but it is powerless to assist patients to stand up and walk.As a new robot technology,lower limb rehabilitation exoskeleton robot provides a new means of motion assistance for lower extremity motor dysfunction patients.It can assist patients in standing up and walking training which can prevent muscle atrophy and joint stiffness of patients.However,exoskeleton has certain limitations in long-distance movement and balance.Therefore,aiming at the various rehabilitation needs of lower extremity motor dysfunction patients and integrating the advantages of wheelchair and lower limb rehabilitation exoskeleton robot,in this paper a multifunctional wheelchair-exoskeleton robot that can assist patients moving,standing up and walking was proposed.The main research contents are as follows:Firstly,according to the physiological structure of human lower limbs and the motion characteristics of standing up and walking,in this paper a new design of mechanism and structure for wheelchair-exoskeleton robot was proposed,including a lifting module,a seat plate adjusting module and an exoskeleton module matching the states of standing,sitting and walking.The strength of the lifting module was evaluated by ANSYS Workbench to verify its reliability.The kinematic simulation of the cable driving system in the seat plate adjusting module was carried out through ADMAS which verifies the feasibility of the cable driving method.Then the construction of the three-dimensional model of the wheelchair-exoskeleton robot was completed in Solid Works.Secondly,according to the characteristics of motor ability of patients with complete disability of lower limbs and patients with incomplete disability of lower limbs,two motion trajectory planning strategies to realize STS process were proposed,and the dynamic analysis of the human model was carried out through Lagrange equation to solve the driving force required for the two motion trajectories,so as to provide a theoretical basis for the construction of the driven system and the selection of control strategy.Finally,the prototype of wheelchair-exoskeleton robot was fabricated,and the control system of the prototype was built,including the hardware system and the control strategy.A method to identify the user’s walking intention through the pressure perception at the left and right wheels of wheelchair-exoskeleton robot was proposed,and the order in which the user tries to start gait was given to improve the friendliness of human-robot interaction.The experimental tests of STS mode,walking mode and manned travel mode of the prototype system were completed.The results verify the effectiveness and feasibility of the wheelchair-exoskeleton robot for movement assistance,standing assistance and walking assistance.