A Multi-DOF Human-Powered Robot Using Regenerative Clutches and Constant-Force Springs

In this paper, the development of a two-degrees-of-freedom (DOF) human-powered robot using regenerative clutches and constant-force springs is described. A regenerative clutch can control a transmitted torque precisely and it includes a regenerative brake and a differential gear mechanism. The single-clutch human-powered joint-drive mechanism developed in this study is a system that can output forward and reverse torques and, to control the joint angle, performs servo control of the joint with one regenerative clutch by offsetting the torque using a constant-force spring. A crank-speed-sensitive spring-locking system has also been developed to implement a safe emergency stop function when the operator stops supplying power. The two-DOF human-powered robot using our systems realized planar trajectory tracking, suggesting that the position control of the end point of a multi-DOF human-powered robot is possible.