Optimum positioning of an underwater intervention robot to maximise workspace manipulability
Underwater robotic vehicles (URV) are extensively used for inspection and intervention tasks of subsea facilities. To enable dexterous manipulations, the URV is required to be firmly attached to the structure. The choice of docking point is very important. An inappropriate choice would necessitate multiple re-dockings. This significantly increases the duration and cost of the mission. In this paper, we present a method of assisting the URV operator to identify the most appropriate docking position in the context of a desired dexterous workspace. The method draws upon classical procedures developed, predominantly, for industrial robotics. Currently, the operator intuitively determines docking positions. A positioning strategy, based on the type of task to be carried out, is proposed. Inspection of a subsea weld joint, using a compact URV and a specially designed and optimised, dexterous, 7 d.o.f., manipulator, is considered as a test case. Dexterity of manipulator at the target location is taken as the optimisation criterion. As a measure of manipulator dexterity, the condition number of the manipulator is adopted here. Manipulator joint limits and workspace constraints are taken into account. Theoretical analysis and simulation results are presented. (c) 2005 Elsevier Ltd. All rights reserved.
optimum positioning urv dexterity condition number underwater manipulation singularity