Demonstration and Dynamic Model Validation of Underwater Locomotion of a Submersible Screw-Propelled Vehicle

This paper presents the development and experimental validation of a dynamic model to characterize the underwater locomotion of a fully submersible screw-propelled vehicle. The Multi-terrain Amphibious ARCtic explOrer or MAARCO is an amphibious rover that uses a pair of helical drives or Archimedes' screws to move on land, on water, and underwater. The locomotion of the rover depends on the thrust generated by the rotating helical blades and the buoyancy force generated by flooding or emptying the central cylinders or ballasts. A submersible prototype is used to demonstrate the underwater locomotion capabilities of the rover, specifically sinking to different depths followed by resurfacing. The dynamic model, based on the Newton-Euler method, is developed using the generalized underwater vehicle's dynamics equation of motion. Hydrodynamic forces such as added mass, viscous drag, buoy-ancy, and gravity are considered in addition to the thrust and buoyancy forces exerted by the helical drives. Results obtained using the dynamic model and experiments performed using the prototype are compared for model validation and possible improvements to the dynamic model are identified.