Research On Physical Human-robot Compliance Interaction Control For Lower Limb Rehabilitation Robot

With the development of rehabilitation medicine and related technological advances,lower limb rehabilitation robots were created to reduce the physical exertion of rehabilitation therapists during the rehabilitation training of stroke patients and to improve the duration of rehabilitation training.There are two main modes of lower limb rehabilitation robotic therapy: robot-assisted mode and patient-initiated mode.In the process of active rehabilitation training,the soft control of physical human-machine interaction helps to ensure the safety and comfort of users,enhance the coordination of human-machine interaction movements,and improve the effectiveness of rehabilitation training.In this paper,the active supple control strategy of the lower limb rehabilitation robot utilizes a user-intent based adaptive trajectory generator and a flow field velocity algorithm were designed to achieve human-machine supple control of the subject in the active rehabilitation training mode.The specific work is as follows.The main contributions of this paper are as follows.Firstly,analyzed the structure of the lower limb rehabilitation robot,the two-degree-of-freedom robot model was established to provide the basis for lower limb rehabilitation robots and their physical human-machine soft interaction control.Among them,the kinematics under the Cartesian spatial coordinate system and the dynamics based on the Euler-Lagrange equation method are introduced,and the kinematic and dynamical models of the system are established respectively.Secondly,the human-robot interaction torque observer is designed based on the robot joint electromechanical coupling model to solve the problem that the human-robot interaction force is difficult to obtain.Then,the sum of trajectory deviations caused by human-machine asynchrony is solved optimally using the most rapid descent algorithm to reduce the human-machine interaction moment generated by human-machine asynchrony,and a specific gait reference trajectory based on the current user is obtained.Then,control strategies with adjustable degrees of assistance and guidance are designed based on the reference flow field principle,thereby forming a control scheme with a hierarchical double-loop structure.Finally,in order to verify the proposed torque observer and the designed control algorithm,an experimental system for the flexible interaction control of the lower limb rehabilitation robot was designed and established.In the experiments,using the lower limb rehabilitation robot system,physical flexibility control tests were conducted to verify the effectiveness and feasibility of the proposed method in terms of both human-robot interaction flexibility and joint motion performance.