Experimental evaluation of adaptive model-based control for underwater vehicles in the presence of unmodeled actuator dynamics

This paper reports a comparative experimental evaluation of proportional derivative and adaptive model-based control for underwater vehicles. To the best of the authors´ knowledge, this is the first such evaluation of model-based adaptive tracking control for underwater vehicles during simultaneous dynamic motion in all 6 degrees-of-freedom. This experimental evaluation revealed the presence of unmodeled thruster dynamics arising during reversals of the vehicle´s thrusters, and that the unmodeled thruster dynamics can destabilize parameter adaptation. The three major contributions of this paper are: an experimental analysis of how unmodeled thruster dynamics can destabilize parameter adaptation, a two-step adaptive model-based control algorithm which is robust to the thruster modeling errors present, and a comparative experimental evaluation of adaptive model-based control and proportional derivative control for fully-actuated underwater vehicles preforming simultaneous 6 degree-of-freedom trajectory tracking.