A modified model, simulation, and tests of a full-scale sailing yacht

Abstract

Sailing yachts have great potential to act as future long-term oceanic observing platforms, yet to date there have not been complete autonomous sailing systems robust enough to handle long term operation in the harsh and continually changing ocean environment. The basis of control system design is a mathematical model capable of describing and capturing the physics based dynamics of the sailboat. The mathematical model represents the system to be controlled, however, a sailing yacht is a very difficult system to model from a controls perspective because of its heavy reliance on the uncontrolled spatial and temporal distribution of the wind. Presented in this paper is a modified aerodynamic force model which includes the sail angle as a control input to the sailing yacht system. The new model has been incorporated into a 4 degree of freedom (DOF) rigid body dynamic yacht model, and implemented in MATLAB/Simulink. The simulations shows model exhibits similar behavior to that observed in full scale sailing yacht sea trial data. Data taken aboard a Precision 23 day-sailer is analyzed, and it is found that the model is a likely candidate for including sail input to a physics based dynamic model for identification and control system design.

Optimal sail angle computation for an autonomous sailboat robot

“…From 3b, we can note that, when wind speed is low, the relation between δ s and Θ V can be approximated by a linear function (as in [13]). In case of high wind speed, the curve begin to be saturated.…”

“…Sailors can also use VPP programs to correct their sailing configurations (VPP are commercial products that give the theoretical maximum velocity of a sailboat for each wind condition [12]). Sailors' skills and experience have been adapted to the case of autonomous sailboats using either a linear relationship between the sail's angle of attack and the sail angle (including or not saturation and hysteresis [3], [13]) or by using fuzzy logic controller [14] [15]. None of these methods is focused on the computation of a sail angle to maximize the longitudinal speed (surge) of a sailboat.…”