Composite adaptive control of astable UUVs

Unmanned underwater vehicles (UUVs) typically operate in uncertain and changing environments. Globally convergent Lyapunov-based parameter-adaptive controllers for six-degree-of-freedom position and attitude trajectory-tracking control of astable UUVs have been successfully derived and applied. We propose an efficient adaptive-control scheme for UUVs based on existing parameter-adaptation schemes popular in the robotics literature. Specifically, we customize bounded-gain-forgetting composite adaptation, which utilizes information about both the tracking and model-prediction errors to yield faster parameter convergence than the traditional tracking-error-based (TEB) adaptation. Hence, better transient behavior of tracking errors is achieved by using fewer control efforts in most cases. We show the effectiveness of applying the suggested adaptation scheme on UUVs through simulation.