Structure And Posture Analysis Of Hydraulic Lower Limb Assisted Exoskeleton Robot

The lower limb assisted exoskeleton robot needs to be worn on the human body to realize human-computer interaction,provide assistance for the wearer and assist the wearer to achieve certain movement.However,due to the flexibility and complexity of the wearer's motion,many degrees of freedom and randomness,the difficulty of exoskeleton robot body structure design and human motion intention capture is increased,resulting in poor effect of stable cooperative motion.Therefore,it is of great significance to study the gait characteristics of exoskeleton and assist robot.In this paper,a lower limb assisted exoskeleton robot is proposed.The humanoid design criteria are used to study the structural characteristics of human lower limbs.A 7-DOF robot body structure with one leg is designed to better meet the needs of human motion.At the same time,the legs are designed to be retractable,which can be used for wearers of different heights.Based on the study of the mechanical body of the lower limb assisted exoskeleton robot,the gait change law of the walking cycle is analyzed,the mathematical model of forward and lateral gait motion is established,the forward and lateral motion gait in the walking process is planned,and the change law of each joint angle in the forward and lateral motion is obtained.Through the gait planning,the human-computer system can be realized more accurately Integrated collaborative gait control.In this paper,the active hydraulic drive system of hip joint flexion and extension motion and the passive auxiliary drive system of pneumatic balance bar are established.The parameters such as cylinder diameter and pressure of hydraulic cylinder are designed and calculated.The hydraulic control system is analyzed and simulated,and the motion parameters such as displacement of hydraulic cylinder are obtained It can provide more kinetic energy for the wearer,realize the smooth transition of speed in the movement process,at the same time,it can realize the overload protection,and provide safety protection for the wearer;the movement process of the pneumatic balance bar is simulated,and the assist performance of the pneumatic balance bar under different loads is simulated.The results show that:in a certain range,with the increase of the load,the pneumatic balance bar can help The effect is more obvious.Based on the zero moment point(ZMP)stability judgment theory,the instability mechanism in the walking cycle is analyzed,and the coordinated control strategy of stable polygon is proposed.The motion stability characteristics of human-machine system are obtained through the shape change of stable polygon and the position relationship between ZMP and the centroid point of stable polygon.The analysis shows that the smaller the absolute value of the difference between the projection position and the centroid of ZMP in the stable polygon,the more stable the man-machine system is.In this paper,the ZMP of the human-machine system and the change law of the stable polygon in the process of walking posture movement are obtained by building the experimental platform of the lower limb assisted exoskeleton robot,which provides the experimental basis for the stability characteristics of the human-machine system cooperative motion.The correctness of the theoretical analysis results is verified by comparing the experimental results with the theoretical analysis results,which provides a reference for the coordinated motion control strategy of the human-machine system New ideas and methods are provided.The experimental results show that the lower limb assisted exoskeleton robot proposed in this paper can assist the work,and ensure the safety and stability of human-computer cooperative movement.