Analysis and Design of Manipulator/Vehicle System on Water Based on Translatability and Rotatability

This paper discusses design issues of a manipulator/vehicle system floating on water, which consists of a vehicle controlled by thrusters and a manipulator mounted on it. The design of the system is very important for the control of such a system, because the controllability of the system is largely affected by the design of the system. In this paper, we propose a method to design the location of thrusters based on the concept of Translatability and Rotatability of the vehicle by actuators. The translatability (rotatability) of the vehicle represents the relationship between the output forces of thrusters and the equivalent force (moment) evaluated at the centroid of the vehicle. We first derive the relationship and then reveal that the equivalent force (moment) forms an ellipsoid. The method is natural in the sense that the force and the moment, which have dfferent dimensions, are dealt with independently. Examples illustrate the effectiveness of the proposed method.