Full State Feedback Foiling Control for America’s Cup Catamarans

Abstract

This article proposes a flight control system for hydrofoiling catamaran sailboats. The main goal was to create a control system that could replace or guide the crew in the tracking of a commanded ride height. The control system exploits the coordination between the main lift source surface, the daggerboard foil, and the stabilization surfaces, the rudder foils. Compared with conventional aircraft, the daggerboard foil is the primary stabilization surface unlike a wing or the flaps of an aircraft. Both the model and the sea trials revealed a high potential sensitivity of the closed-loop systems to wave disturbances. This sensitivity arises from both the hydrodynamic effect of the waves on the foils and the noise in the ride height estimates due to the waves’ random water height variation. We describe the full state feedback (FSF) controller, for which the linear–quadratic regulator (LQR) theory-based gains were initially adopted and then modified with manual tuning, so that the developed system was able to perform almost as well as the highly trained helmsmen. Ancillary components of the control system, such as the ride height estimator, are also described.