GRASPER: A Multisensory Based Manipulation System for Underwater Operations

• Main Authors: Sanz, P. J., Penalver, A., Sales, J., Fornas, D., Fernandez, J. J., Perez, J., Bernabe, J.
• Format: Conference Proceeding
• Language: English
• Subjects: 3D reconstruction; Grasping; Lasers; semiautonomous grasping; Solid modeling; Tactile sensors; Three-dimensional displays; Underwater intervention mission; underwater object recovery
• ISSN: 1062-922X; 2577-1655
• DOI: 10.1109/SMC.2013.689

This paper presents the progress that has been made recently in the TRITON project. The TRITON project is an on going research project being carried out in Spain which has as principal objective the production of an AUV capable of autonomous underwater interventions. The GRASPER sub-project focuses on developing the necessary manipulation skills. Currently, a lot of research in the underwater robotics context is developing increasing levels of autonomy for all kinds of intervention operations, which always require some kind of physical interaction. However, if autonomous robotic manipulation on land remains a relatively undeveloped field, the situations is at an even more primitive stage in underwater scenarios where currently the systems are tele-operated by an expert user from a surface vessel. Only very few underwater systems have the capacity to carry out manipulation without any kind of umbilical cables teleoperating these actions. In particular, this work introduces a new approach for increasing the autonomy levels of an underwater manipulation system, discussing also preliminary results. In order to test this concept, different objects, without predefined models, are approached and recovered from the bottom in water tank conditions. To achieve this purpose, a scan of the scene is performed using a structured laser beam attached to the forearm of the manipulator. At the same time, a digital video camera is used to capture the scene with the laser beam projected onto the object. The laser stripes are triangulated to obtain a 3D point cloud. Moreover, the underwater robot gripper is provided with strain gauge tactile sensors, which enable the execution of a more reliable grasp. On the other hand, the process is shown inside an underwater simulator previously developed, named UWSim, acting in this case as a virtual representation of the real environment. This virtual representation allows the user to specify the grasp, highlighting how the virtual grasp will be defined for the selected target. The feasibility and reliability of the underwater manipulation system is demonstrated though the experimental results.