Balancing control algorithm for a 3D under-actuated robot

This paper presents an angular momentum based controller to control the balancing motion of a spatial underactuated robot with three degrees of under-actuation. The control algorithm is based on the idea of decoupling the robot´s motion instantaneously into bending and swivelling motions. This property of the robot is obtained by using a constant velocity joint as the 2-DoF active joint of the robot. Simulation results show the performance of the controller during some interesting motions of the robot such as straightening, crouching and reorienting motions. The last two motions, which are the results of decoupling the robot´s motion, are demonstrated here for the first time.