Research And Implementation Of A Lower-limb Exoskeleton Robot Up And Down Stairs

Paraplegic patients could take care of themselves with the assistance of the lowerlimb exoskeleton robot and it would have great benefits for their physical and mental health.As the indispensable part of independent life,up and down stairs play an important role in daily life.Therefore,the function of exoskeleton up and down stairs is the key function of exoskeleton to adapt to the external environment.Based on the original exoskeleton prototype,this thesis realizes the natural and stable excavation of different sizes of stairs.The main research contents of this thesis are as follows:In order to reduce the complexity of the experiment and provide a theoretical basis for the experiment.This thesis establishes the simulation model of the exoskeleton up and down stairs depended on the original functional prototype;Specifically,the relationship of the joint angle by positive kinematics and the movement track of the connecting rod's terminal is established with the D-H(Denavit-Hartenberg)coordinate system,meanwhile the homogeneous transformation method is used for describing rigid body.Then we combined with the forward and inverse kinematics to analyze the Zero Moment Point(ZMP)of the gait trajectory,which is aim to judge the stability of the model.Besides,for purpose of the natural and stable up and down stairs of the exoskeleton,the study of the overall strategy formulation and gait planning algorithm play important role in the model.Firstly,to deal with stair detection and gait planning,the overall strategy of up and down stairs is analyzed and proposed two different strategies.Combining two gait planning strategies,a cubic spline interpolation algorithm and trajectory planning algorithm based on dynamic movement primitives(DMPs)are proposed.The simulation model is used to compare the simulation results of the two algorithms to determine the trajectory planning algorithm with the smoothness and bionics as the evaluation criteria.Due to the trajectory of the DMPs algorithm exist the trajectory scaling imbalance and energy loss,we apply the truncation method,artificial potential field method and biological obstacle avoidance method to ensure the optimal optimization based on the bionics and energy as the measurement standard.Finally,the stability analysis of ZMP is carried out to verify the stability of DMPs generated trajectories.Finally,to verifies the feasibility and practicability of theoretical strategies and algorithms through experimental prototypes.For the size measurement and pressure detection of stairs,an intelligent sensing shoe is designed to deal with it.The height and width of the stairs are detected by a laser sensor,and the pressure of the sole is detected by an oil pressure sensor.Through experiments to verify the accuracy of the sensor and the accuracy of the detection,combined with the detection strategy and gait trajectory planning algorithm,the exoskeleton physical prototype can naturally and stably up and down the stairs according to the generated target trajectory,and compare the gait before and after the optimized gait.The energy consumption is lower than the original gait.