Kinematic performances evaluation of a hydraulic underwater manipulator

Underwater manipulation is an essential operation for performing a diverse range of applications in the submerged environment that, in spite of the hostile and unstructured environment, it requires high precision and reliability of the robotic arm. The paper presents the evaluation and characterization of the kinematic performances of an underwater robotic arm mounted on a light work class ROV. The arm analyzed in the study is a re-engineered version of a commercial hydraulic manipulator whose geometry and end-effector have been modified. Moreover, the arm has been equipped with a set of encoders in order to provide the positioning feedback. The test conducted in laboratory focused on the measurement of accuracy and repeatability in order to evaluate the limits of the arm architecture. This work has been carried out in the context of the CoMAS (In situ conservation planning of Underwater Archaeological Artifacts — http://www.comasproject.eu) project in which the possibility to develop a ROV able to perform maintenance operations in underwater archeological sites has been investigated.