Drive of the Powered Exoskeleton and Driving Compensation with the Human-Machine Coupling Interaction While Squatting

For the existing problem that the powered exoskeleton can't squat smoothly due to unclear characteristics of the joint drive, the joint drive of the powered exoskeleton while squatting and its compensation with the human-machine coupling interaction are investigated to enhance squatting reliability and human-machine interactivity. The kinematic equations of all joints are obtained through a somatic data acquisition experiment and nonlinear data-fitting. A human-machine coupling dynamic model during squatting is established, and the driving features of all joints are analyzed. It is found that the driving features and their volatility at knee joint are significantly greater than those at ankle and hip joints, there is a strong coupling between the driving torque and the angular acceleration at knee joint, and the system centrobaric displacement has significant influence on the drive at knee joint only in the first half phase of squatting. These analyses on the joint driving features show that the double-acting linear hydraulic cylinder can be used to drive the knee joint, and the human-machine interaction force can compensate the partial driving torque at ankle joint and the whole driving torque at hip joint.