Developing a Framework for Modeling Underwater Vehicles in Modelica

Abstract

When developing Remotely Operated Vehicles (ROVs), models prove extremely useful in determining design parameters and control strategies. This paper's goal is to develop a modeling framework for underwater ROVs in Modelica, with integration with the Robotic Operating System (ROS), allowing for quicker prototyping and testing of ROV design and control. Named the Underwater Rigid Body Library (URBL), the modeling framework treats the effect of water on submerged bodies as interactions with a "field" of water to capture the effects of buoyancy and drag. Its usage is demonstrated by applying it to the BlueROV2, a commercially available ROV from Blue Robotics. Using controller signals to the propellers as system inputs, the model was tested with various motor command profiles to achieve different composite motions. Constant motor commands were provided both from within Modelica and from ROS; the simulation results indicated that the model responded appropriately.