Robust adaptive control of Underwater Vehicles for precision operations

Using an Autonomous Underwater Vehicle (AUV) for close-proximity operations (e.g., close to the seafloor, a vessel, or divers) requires robust, precise vehicle control. When performing joint human-robot operations, a Robotic Diver Assistant can perform tasks such as tool carrying, worksite illumination, or other tasks that a dive buddy might perform. Precise control of the AUV normally requires accurate knowledge of the vehicle´s dynamics; however, such models are difficult to obtain. Furthermore, the utility of the resulting model is diminished if, for example, the vehicle configuration changes intentionally or unexpectedly. An ideal control system allows the AUV to handle uncertain environmental conditions, varying payload configurations, and actuator failures. Adaptive control can give an agile AUV the necessary robustness for close-proximity operations, including joint robot-diver operations. Model Reference Adaptive Controls is investigated here for heave control of an agile, tethered, hovering-capable AUV, ACQUAS.