Station Keeping and Segmented Trajectory Control of a Wind-Propelled Autonomous Catamaran

Precision guidance and control of an autonomous, wind-propelled catamaran has been demonstrated by the Atlantis, a modified Prindle-19 catamaran, to be experimentally capable of tracking straight line segments to better than 0.3 meters (1 - sigma). This paper extends Atlantis´s guidance and navigation system to provide precision control while traversing a series of way-points and adds station keeping functionality that is the ability for Atlantis to maintain her position at a given way-point in the presence of unknown water currents while motor powered. To achieve this, segmented trajectories are developed using the specified way-points forming line segments and arcs as path primitives. If a segment is unreachable directly due to the wind direction, a real-time tacking control mode is enabled and the Atlantis tacks within a given lane width until its destination is reached. For simulation a nonlinear model of the Atlantis was developed that includes realistic wind and water current models. Monte Carlo simulations of this new guidance and control system on the nonlinear model demonstrate the Atlantis is capable of maintaining a cross-track error of less than one meter throughout the path