Underwater Dynamics, Controls and Trajectory Tracking of an Amphibious Screw-propelled Vehicle for Arctic Exploration

The Multi-terrain Amphibious ARCtic explOrer (MAARCO) rover is an amphibious screw-propelled vehicle designed to traverse Arctic terrains seamlessly. The propulsion system consists of two helical drives, similar to Archimedes’ screw, that consist of hollow cylindrical ballasts wrapped in auger or screw-shaped blades. In addition to moving on land and on water, the rover is also able to move underwater. The variable buoyancy offered by the ballasts, which can be flooded or emptied, and the thrust offered by the rotating helical blades enable the rover to operate underwater. In this paper, a dynamic model based on the Newton-Euler method is developed using the generalized underwater vehicle’s dynamics equation of motion. The hydrodynamic forces considered on the underwater rover include added mass, viscous drag, buoyancy, and gravity. In addition to the hydrodynamic forces, the rover also experiences the thrust and buoyancy forces exerted by the helical drives. The dynamic model is used to test a control design for 3-dimensional trajectory tracking underwater. The errors in position and velocity are used to create a reference velocity error and a composite error as feedback to the controller. The results of the simulations show that the rover can accurately track several 1-, 2-, and 3-dimensional trajectories using the controller in conjunction with the dynamic model.