Motion planning and control of robotic manipulators on seaborne platforms

Abstract

Robots on ships have to endure large inertial forces due to the non-inertial motion of the ship. The ship motion affects both the motion planning and control of the manipulator, and accurate predictions can improve performance substantially. It is thus important to investigate to what extent it is possible to predict the future motion of a ship. Based on these predictions, this paper presents a new approach to motion planning and control of such manipulators. It is shown that the effects of the non-inertial forces can be eliminated—in fact, the robot can even leverage the inertial forces to improve performance compared to robots on a fixed base. In particular it is shown that by including the inertial forces in the motion planning the wear and tear on the robot due to these forces can be reduced substantially. To perform realistic experiments a 9-DoF robot is used. The first five joints are used to generate the real ship motion, and the last four joints are used for motion planning. The dynamic coupling between the first five and the last four joints is thus exactly the same as the dynamic coupling between a ship and a manipulator, which allows for very realistic experiments.