A unified mathematical model for synchronisation and swarming has recently been proposed. Each system entity, called a "swarmalator", coordinates its internal phase and location with the other entities in a way that these two attributes are mutually coupled. This paper realises and studies, for the first time, the concept of swarmalators in a technical system. We adapt and extend the original model for its use with mobile robots and implement it in the Robot Operating System 2 (ROS 2). Simulations and experiments with small robots demonstrate the feasibility of the model and show its potential to be applied to real-world systems. All types of space-time patterns achieved in theory can be reproduced in practice. Applications can be found in monitoring, exploration, entertainment and art, among other domains.
The miniaturization of microrobots is accompanied by limitations of signaling, sensing and agility. Control of a swarm of simple microrobots has to cope with such constraints in a way which still guarantees the accomplishment of a task. A recently proposed communication method, which is based on the coupling of signal oscillators of individual agents [13], may provide a basis for a distributed control of a simulated swarm of simple microrobots (similar to I-Swarm microrobots) engaged in a cleaning scenario. This self-organized communication method was biologically inspired from males of chorusing insects which are known for the rapid synchronization of their acoustic signals in a chorus. Signal oscillator properties were used to generate waves of synchronized signaling (s-waves) among a swarm of agents. In a simulation of a cleaning scenario, agents on the dump initiated concentrically spreading s-waves by shortening their intrinsic signal period. Dirt-carrying agents localized the dump by heading against the wave front. After optimization of certain control parameters the properties of this distributed control strategy were investigated in different variants of a cleaning scenario. These include a second dump, obstacles, different agent densities, agent drop-out and a second signal oscillator. One of the essential benefits of swarm robotic systems is redundancy. In case one robot breaks down, another robot can take steps to repair the failed robot or take over the failed robot's task. Although fault tolerance and robustness to individual failures have often been central arguments in favor of swarm robotic systems, few studies have been dedicated to the subject. In this paper, we take inspiration from the synchronized flashing behavior observed in some species of fireflies. We derive a completely decentralized algorithm to detect non-operational robots in a swarm robotic system. Each robot flashes by lighting up its on-board light-emitting diodes (LEDs), and neighboring robots are driven to flash in synchrony. Since robots that are suffering catastrophic failures do not flash periodically, they can be detected by operational robots. We explore the performance of the proposed algorithm both on a real-world swarm robotic system and in simulation. We show that failed robots are detected correctly and in a timely manner, and we show that a system composed of robots with simulated self-repair capabilities can survive relatively high failure rates.