Development of a simulation platform for underwater transportation using two hovering autonomous underwater vehicles (HAUVs)

Abstract

This paper considers two HAUVs undertaking underwater transportation of a spherical payload via cylindrical manipulators. The rigid body connection method of transportation is explored. In this analysis, the nonlinear coupled dynamic model is developed to get an accurate representation of the actual system. Hydrodynamic parameters for all the part bodies are calculated about the centre of the combined system. The hydrostatic terms of the HAUVs and manipulators are selected such that their weight is slightly less than the buoyancy, in order to bring the entire system to surface in case of an emergency. The weight of the payload is selected such that the difference between weight and buoyancy is within the thrust limit of the vertical thrusters on the two HAUVs. The propulsion model is developed taking the effect of all the thrusters on the two HAUVs about the combined centre of body. The simulation platform is developed to observe the response of the entire system and of the individual HAUVs in the system at different revolutions of the thrusters. The stability of the entire system is ensured by maintaining the connection between the vehicles and payload. The simulation results show that stability and motion accuracy are compromised in the axial direction due to the opposite revolutions of the axial thrusters on the two HAUVs.