The Research On Joint Drive And Motion Stability Of Lower Limb Augmentation Exoskeleton Robot

With the continuous updating of military technology,the frequent occurrence of natural disasters,the increasingly serious problem of aging population and the continuous improvement of intelligent manufacturing requirements,the exoskeleton robot as an intelligent augmentation equipment has been focused on in various fields.The breakthrough of key technologies of force-boosting exoskeleton robot can effectively promote the development of national defense security,people’s life safety,social operation efficiency and industrial production level.In the process of actual research,in the face of complex usage scenarios and variable load conditions,ensuring the stability of lower limb force-enhancing exoskeleton robot movement is the difficulty of current research,and is also the key premise for realizing other functions.To achieve good force-enhancing effect,joint drive control technology needs to be improved.Therefore,in order to achieve stable walking and load-bearing after human body wearing,this paper carries out research on motion stability and joint drive control of the lower extremity force-enhancing exoskeleton robot.The main research contents are as follows:(1)Mechanism design and analysis of lower limb force-enhancing exoskeleton robot.The main mechanical structure of the lower limb augmentation exoskeleton was designed according to the dimension parameters of the lower limb structure,the human movement gait,especially the process of climbing the stairs and the CGA gait data.According to the design size of the main structure and the mapping relationship between the robot joint Angle and the displacement of the joint driver,the maximum working pressure,cylinder diameter,piston stroke and other main parameters of the hydraulic joint driver were determined.(2)Kinematics and dynamics modeling of lower limb augmentation exoskeleton robot.Aiming at the two main gaits of the robot,walking on the ground and climbing the building,the D-H model method was used to complete the kinematics analysis and modeling of the main structure,and the Lagrange equation was used to carry out the dynamic analysis and modeling,and the joint torques were defined.According to the basic principle of joint drive system,a reasonable and accurate dynamic model of joint drive system was established.(3)Study on the motion stability of the climbing process.Aiming at the more difficult process of climbing,the zero moment theory was used to analyze the stability,and the ZMP coordinates,stability region and stability margin were derived.The virtual prototype model was established,and the simulation verified that the lower limb augmentation exoskeleton robot could maintain good coordination during the climbing process.The stability of the robot was evaluated through the centroid trajectory diagram to verify its motion stability.The simulated data such as the joint Angle of the exoskeleton robot can provide support for subsequent joint drive control research and experiments.(4)Research on joint drive control of lower limb force-enhancing exoskeleton robot.Aiming at the problem that joint control is difficult when the control object is a typical nonlinear and time-varying system with variable load,a force control algorithm based on sliding mode variable structure control and radial basis neural network control is proposed,and the control law is designed.The force tracking simulation of sinusoidal and variable load signals can achieve better control effect compared with PID control.The joint driving force control experiment platform was built,and the step response force control experiment was carried out.The corresponding force tracking curve was obtained,and the effectiveness of the simulation results and the followability and adaptability of the control algorithm were verified by further experiments.