Reynolds flocking in reality with fixed-wing robots: Communication range vs. maximum turning rate

The success of swarm behaviors often depends on the range at which robots can communicate and the speed at which they change their behavior. Challenges arise when the communication range is too small with respect to the dynamics of the robot, preventing interactions from lasting long enough to achieve coherent swarming. To alleviate this dependency, most swarm experiments done in laboratory environments rely on communication hardware that is relatively long range and wheeled robotic platforms that have omnidirectional motion. Instead, we focus on deploying a swarm of small fixed-wing flying robots. Such platforms have limited payload, resulting in the use of short-range communication hardware. Furthermore, they are required to maintain forward motion to avoid stalling and typically adopt low turn rates because of physical or energy constraints. The tradeoff between communication range and flight dynamics is exhaustively studied in simulation in the scope of Reynolds flocking and demonstrated with up to 10 robots in outdoor experiments.

I. Introduction

Swarm behavior is often dependent on the ability of robots to interact. In most swarm experiments, interactions rely on communication hardware to broadcast messages to neighboring robots. However, interactions can be compromised if the robots are not able to communicate at a range that is suitable with respect to the speed at which they can react. As shown in Fig. 1, a robot that has a small communication range will need to aggressively alter its trajectory to prevent communication breaks. Likewise, a robot that is not able to maneuver quickly will need to communicate at longer ranges. Fig. 1. Schematic illustrating the relationship between motion dynamics and communication range on swarm interactions. Here the robot shown in grey attempts to align heading with the black robot by turning as fast as possible. Because the robot has limited turning rate, communication is lost during the maneuver