In this paper, four Seaperch HAUVs were considered rigidly connected to a payload via solid plate links. A nonlinear coupled dynamic model was developed using the Newton-Euler formulation including the inertia, Coriolis, hydrodynamic, hydrostatic and thrust terms. The hydrodynamic parameters were calculated using the semiempirical approach. The vehicles and the solid links have their buoyancy greater than weight, however, the payload was selected such that the whole system is neutrally buoyant. Time-domain motion simulation was initially carried out without implementing the control system to verify the motion response. A control system was then designed using the PID controllers. Low PID gains were analysed to be enough to reach the desired location without following a trajectory. A minimum snap trajectory was then generated, and the control system was applied to follow it. At the lower PID gains, the trajectory following had a high time lag and also the thrust forces which were applied to follow the trajectory had slackness. This was not acceptable as this resulted in the failure of the transportation mission. Therefore, the PID gains were increased to a reasonable range and the acceptable trajectory tracking was achieved.
展开▼
