Gait Planning And Gait Control Of Lower Extremity Disability Assisted Rehabilitation Exoskeleton Robot

The lower limb exoskeleton robot is a typical human-robot interaction device with broad application prospects in industrial field,military field,and rehabilitation medical field.Its technology involves many aspects such as structure,material,sensor,motion intention recognition,and motion control.In this paper,we propose a wearable exoskeleton robot for lower limb disability assistance rehabilitation,which will be studied from four aspects: human gait acquisition,kinematics and dynamics analysis,gait planning,and control strategy.Gait change is the most typical motion characteristic of human walking,and gait information acquisition is the prerequisite for the realization of gait motion of exoskeleton robot.In this paper,we build a wearable human gait acquisition system and design a plantar pressure acquisition device and a joint motion information acquisition device.In order to ensure the correctness of the collected data,calibration tests and adaptability tests are designed to exclude the influence of different test environments on data acquisition.On this basis,the valid data of human lower limb joint angle motion information and plantar pressure changes are collected.In terms of kinematics and dynamics analysis,the kinematic model of the lower limb assisted rehabilitation exoskeleton robot was established using the D-H parameter method,and the spatial position and posture of the end joints in the absolute coordinate system and the joint angles were obtained by the positive and inverse kinematic analysis.The Lagrangian method was used to establish the single-leg supported walking 7-bar model and the double-leg supported walking 7-bar model of the lower limb assisted rehabilitation exoskeleton robot,and the corresponding Lagrangian functions and Lagrangian equations were obtained.For gait planning,this paper first analyzes the stability of the exoskeleton robot and uses the fuzzy logic gait method to perform gait phasing on the collected plantar pressure change information.Secondly,the motion curves of each joint of the exoskeleton robot are parametrized by using the cubic spline interpolation method and Matlab modeling to verify the rationality and effectiveness of the planning.Finally,the PD control strategy based on model compensation is proposed,the controller is designed,stability analysis and simulation analysis are conducted,and the sliding mode control strategy based on the computational moment method is proposed to address the problems of modeling errors and external disturbances in this method.The Simulink simulation shows that the sliding mode control based on the computational moment method has good robustness and can achieve the tracking control of the gait joint trajectory of the lower limb assistive rehabilitation exoskeleton robot.The test results show that the gait planning is reasonable and the sliding mode control method based on the computational moment method can effectively control the lower limb assisted rehabilitation exoskeleton robot and has good stability.