Development of underacuated hybrid mobile robot composed of rotors and wheel

Abstract

The purpose of this research is to develop the combination mobile system composed of coaxial rotors and single driving wheel. A conventional combination mobile system causes increase of the number of actuators, because actuators are never shared by each mobile mechanisms, but are adopted for each mobile mechanism individually. However, the actuators in the proposed mobile system are shared by combined two mechanism. The proposed system minimizes an increase the number of actuators by two methods : First one is dispensing with a steering motor in wheel mechanism and second one is dispensing with a pitch servo motor in rotor mechanism. As the first one, a counter torque generated by rotors changes the orientation of the body, and it becomes substitute of steering function in wheel mechanism. A counter torque, originally, is negative effect disturbing an orientation of a mobile system. However the proposed system actively uses this counter torque to realize steering function as wheel mechanism. By rotating the rotor, the counter torque is applied to the body. And then the orientation of the body is changed. By this manner, it is possible to control the orientation of the body. As the second one, when the robot passes over obstacles, the wheel motor add the initial velocity to the robot, it can be gone forward direction by inertial force. It becomes substitute of pitch control function in rotor mechanism. By this manner, it is possible to control the spatial moving in forward direction. In particular, this paper introduced the prototype, discussed the study on energy efficiency and experimental results of the estimation of horizontal spatial moving.