A Method for Identifying Knee Joint Stiffness During Human Standing.

During human-robot interaction, the robot should react according to the change in the human body state. The stiffness is one of the important information. It is closely related to the stability and comfort in human movement. At present, the auxiliary equipment for standing does not consider the change of human joint stiffness. Therefore, this paper proposes a method that can identify the stiffness of the knee joint during human standing. Firstly, the human body structure is simplified to a three-section inverted pendulum model. The kinetic analysis is performed using Lagrange’s equation. Then the expression of joint stiffness is solved by joint torque. The angles and angular velocities of the joints of the lower limbs of the human body during standing are measured experimentally. The errors in the measurements are modified by geometric relationships. The stiffness of the human body during standing is derived by substituting them into the derived expressions. The result shows that the method can identify the stiffness of the human knee joint during standing.