Equilibrium Point Control of a Robot Arm with a Double Actuator Joint

This paper presents the Double Actuator Joint Mechanism, a novel mechanism for robots to generate human-like motion. The mechanism is based on the idea of the equilibrium trajectory hypothesis, a hypothesis that multi-joint limb movements are achieved by shifting the limbs equilibrium positions defined by neuromuscular activity. The magnitude of force exerted on the arm depends on the difference between the actual and equilibrium positions, and the stiffness and viscosity about the equilibrium position. Two actuators will be placed on each joint of a twolinked manipulator, one to control position, and the other to control stiffness of the joint. By so creating human arm-like behavior, this mechanism allows robot limbs to execute stable motion in an unknown environment, owing to its ability to tolerate shock upon contact using a very simple control scheme. The underlying theory and implementation issues of the proposed mechanism are discussed, and experimental results show the potential of our approach.