Abstract
Human characteristics are supposed to be applied to the control systems of the human-friendly robots. Therefore, it is important to know the human characteristics in human-robot cooperative tasks. In this study, we considered a single rotational degree of freedom experimental system as well as a mass-spring-damper-friction dynamic model for the human arm, measured the torque acting on the armload from subject's forearm and the angular displacement of subject's forearm using the force sensor and the eddy current sensor, analyzed their mutual relation, and attained the characteristics of the human arm with the effect of the gravity load. We compared this cooperative motion to that studied without the gravity load and found that the damping and friction characteristics remained unchanged and the spring characteristics disappeared. In this case, the characteristics of the follower's arm had no relationship with the weight of the load.