An adaptive controller for autonomous underwater vehicles

This paper introduces an adaptive tuning method for the controllers of a 4 degrees-of-freedom autonomous underwater vehicle. The proposed scheme consists of two control loops, one for position control and an inner one for velocity control. The gains of the controller are determined on-line, according to the position/velocity errors. Using the proposed adaptive architecture, the uncertainties in the parameters of the system are addressed and the system is able to operate when hydrodynamic disturbances are present. The complexity of the fixed gain tuning procedure is also greatly decreased for underwater vehicles when the algorithm suggested here is used. Experimental results with the Nessie VII AUV show that the adaptive controller is beneficial for underwater vehicles. Finally it is shown that the current approach reduces the energy consumption of the system.