Rail-guided robotic end-effector position error due to rail compliance and ship motion

A rail-guided robotic system is currently being designed for the inspection of ballast water tanks in ships. This robotic system will manipulate sensors toward the interior walls of the tank. In this paper, the influence of rail compliance on the end-effector position error due to ship movement is investigated. An analytical model of the six degrees-of-freedom (DOF) rail stiffness is presented and implemented in a reduced-order analytical frequency response model. This model describes the transfer function between ship acceleration and end-effector position as a function of rail geometry and material properties. Moreover, the influence of the robot compliance is investigated, resulting in design parameters for the robot. The models and calculations are evaluated and compared with a multibody model and prove to be accurate. The analytic models indicate whether or not a proposed robotic system is feasible and if so, optimize rail dimensions, material and robot design. A use-case scenario has been developed which shows that the proposed design will be unlikely to meet the requirements of this robot system design; therefore an alternative design strategy is recommended.