Embodiment of an Aquatic Surface Vehicle in an Omnidirectional Ground Robot

Abstract

The use of unmanned aquatic surface vehicles as a tool for exploring and inspecting bodies of water, such as lakes and ponds is a research area of growing interest. However, using real aquatic vehicles to test and develop software and control systems is often not feasible for many researchers, due to the limited access to testing pools and the lack of availability of low-cost, off-the-shelf surface vehicles. An alternative is to utilise software simulations, but these can fail to test important system features, such as error characteristics of real sensors, on-board processing and the effect of external disturbances on the performance of positional control systems. The contribution of the present paper is a third method that allows the robot's full software system including real world sensors to be tested without the need for pool facilities. This is achieved by mapping the physics of an omnidirectional aquatic surface robot onto an omnidirectional ground vehicle. A dynamic model of the aquatic surface vehicle is deployed within an embedded control system on the ground vehicle, meaning that for a given command signal (applied force) the motion of the ground vehicle mimics the motion that would occur if it were a surface vehicle floating on a body of water. Validation tests demonstrate that the ground vehicle's dynamic behaviour matches well with that of a specific aquatic surface vehicle that was utilised in this study. However, by changing the dynamic model within the embedded control system, the ground vehicle is able to approximate the motion of any aquatic surface vehicle. The newly constructed ground robot is now an open-source and open-hardware platform.