Abstract-Multi-vehicle swarms offer the potential for increased performance and robustness in several key robotic and autonomous applications. Emergent swarm behavior demonstrated in biological systems show performance that far outstrips the abilities of the individual members. This paper discusses a lightweight formation control methodology using conservative potential functions to ensure group cohesion, yet requiring very modest communication and control requirements for each individual node. Previous efforts have demonstrated distributed methods to navigate a vehicle swarm through a complex obstacle environment while remaining computationally simple and having low bandwidth requirements. It is shown that arbitrary formation can be held and morphed within the lightweight framework. Simulations of the lightweight framework applied to realistic nonholonomic tricycle vehicles highlight the swarm's ability to form arbitrary formations from random initial vehicle distributions and formation morphing capabilities, as well as navigate complex obstacle fields while maintaining formation. The non-holonomic constraints are used to implement realistic controls.

Abstract-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 − σ). 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 demonstrates the Atlantis is capable of maintaining a cross-track error of less than one meter throughout the path.

An autonomous surface vehicle, based on a Prindle-19 catamaran and substituting a self-trimming vertical wing for the sail, was developed to demonstrate precision guidance and control. This vehicle, the Atlantis, was demonstrated to track straight line segments to better than 0.3 meters (one σ) when already trimmed for sail along the segment. In order to make the Atlantis useful as an autonomous vehicle, however, more complicated paths are required than simple straight line segments. A segmented trajectory is developed based on waypoints, segments, and arcs as the path primitives. A control architecture is also developed which can traverse a segmented trajectory made of linked path primitives, given reachability constraints due to wind direction.For segments where the destination is unreachable due to the wind direction a lane width is established and an on-the-fly tacking mode is used to traverse the segment while remaining within the lane width. A nonlinear model of the catamaran was simulated using Simulink, including realistic wind and current models. The control architecture was applied to the simulated catamaran using Monte Carlo simulations which demonstrated very robust segment traversal while maintaining a crosstrack error of less than one meter throughout the path.

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