On the influence of ship motion prediction accuracy on motion planning and control of robotic manipulators on seaborne platforms

Abstract

Abstract-Robotic manipulators on non-inertial platforms, such as ships, have to endure large inertial forces due to the non-inertial motion of the platform. When the non-inertial platform's motion is known, motion planning and control algorithms can eliminate these perturbations-in fact, in some situations the motion planning algorithms can even leverage the inertial forces to more cheaply move to a target point. However, for many non-inertial platforms, the motion is unknown.In this paper we investigate how prediction errors and the choice of the prediction horizon affect the motion planning and control of robots mounted on a non-inertial base with a particular focus on seaborne platforms. We study the following three aspects: (i) We study prediction of ship motion and how prediction errors affect the motion planning and control of the manipulator. (ii) We evaluate the relationship between prediction accuracy and control. In particular, we study what prediction horizon length is useful for motion planning and control. We also consider how uncertainties in the ship motion predictions map to uncertainties in the future state of the robot and how to include the variance in the cost function to increase the optimal horizon length. (iii) Finally, we study a receding horizon approach, which re-solves the optimal control problem on-line over a horizon as determined to be meaningful from (ii). Several simulations are presented and, to our knowledge, for the first time experiments of ship-manipulator systems based on real ship motion data are presented.

Dynamics of Two Active Autonomous Dock Mechanisms for Auv Recovery

“…These are typically used for precision tasks but on a relatively small size scale. Control of ship board robotic manipulators has been explored by From et al [19]. They augment a Proportional-Derivative (PD) controller with a real-time wave prediction model to overcome the non-inertial effects of the manipulator base and optimize joint torques for prescribed trajectories.…”

A Geometric Approach to the Design of Serial and Parallel Manipulators with Passive Joints

“…This is for example the case when the base moves with an angular velocity, for example ships or a moving vehicle (From et al [17]). …”

Tracking and regulation control of a 2-DOF robot arm with unbalance

“…The model obtained is standard and is similar to those one finds in the literature, [5], [6], [15], [16]. The obtained base disturbance model is then represented as an external disturbance and the resulting simplified model is then linearized about a natural operating point.…”

“…In this work, a two degree-offreedom Revolute-Revolute (RR) joint robot arm mounted on a vessel and is influenced by sea disturbances is modeled. The disturbance modeling is the main issue and [15], [5], and [6] focus on this with the objective of compensating the effects of these disturbances on robots. On the other hand, in [11], the authors use a combination of a linear and nonlinear controller and an adaptive algorithm, where the linear agorithm is based on internal model principle to regulate disturbances, to solve the tracking and regulation problem for uncertain mechanical systems.…”