A Redundancy Resolution Method for Free-Floating Underwater Manipulation

Underwater manipulation with free-floating autonomous underwater vehicles (AUVs) is an under-explored research area that this paper addresses. The open-source mechanical, electrical, and software designs of an AUV and continuum manipulator system are provided as a platform for performing this research. The underwater robot system has high degrees of freedom including the vehicle body motion and the manipulator joints. Therefore, when performing a manipulation task, the robot has many different potential trajectories which satisfy the task constraints, and this kinematic redundancy needs to be resolved. This paper provides a method for solving the redundancy problem. The relevant kinematic models are derived in order to build an algorithm to calculate desired joint velocities in real time. Different methods to optimize the algorithm for specific tasks are proposed, including a basic weighting method and a gradient projection method to optimize a user-defined objective function. Both simulation and experimental results are analyzed to assess the performance of this algorithm.