Tangible Swarm: see the unseen

Eduardo Castello 

Tangible Swarm is a tool that displays relevant information about a robotics system (e.g., multi-robot, swarm, etc.) in real time while the system is physically conducting its mission. Information such as robots' IDs, sensor inputs, robot trajectories, distance between robots, battery status, communication patterns, etc. can be easily displayed and customized for different missions and scenarios.

Swarm and multi-robot systems have the potential to revolutionize many industries, from last mile delivery to mobility networks. However, debugging these systems, especially when there is a large number of robots involved remains an extremely complex task. To better understand the behavior of these systems, we built a visualization tool capable of collecting relevant information from the robots in real-time and display it onto the robots’ physical working space.

Tangible Swarm builds upon the idea of creating a closed-loop control between a camera that acts as the sensing part (e.g., performing tag tracking, pattern recognition, etc.),  an agent-based simulator as the computational element, and a projector that fulfills the actuation component.  The proposed tool can be extended to a wide range of use cases ranging from novel robotic art installations to changing urban scenarios.  

System architecture

Fig. 1  shows a bird's eye view of the arena built to conduct the experiments to demonstrate the proposed tool. The arena is a rectangular area of 2.5 x 2.5 m2. This experimental area is divided into a 5 x 5 grid where each cell corresponds to a 0.5 x 0.5 m2 area. 

Fig. 2  shows a diagram of the arrangement of the sensing module; a camera performing the tracking of the robots and of the actuation component; a projector displaying information on the arena. 

Fig. 3 shows the information workflow that takes place during these experiments. First, each robot (e-puck) carries a tag; this tag encodes a specific robot ID used in the system. Second, tags are recognized by a vision-based tracking system using a camera right on top of the arena. Third, (x,y,z) coordinates for each tag are calculated with respect to the bottom-left corner of the arena and sent to a ROS multi-master network where the robots are connected in a decentralized manner.  Robots publish information such as their battery level, neighbor IDs, sensor inputs, etc. into this network. Then, this information is extracted from the network and sent to Gama, an agent-based simulation software. With this information, Gama is able to create a virtual representation of the current state of the arena which is projected on the arena itself by using a short throw projector. 

Finally, Fig. 4 shows a snapshot of an experiment where a rich virtual representation of the arena (e.g., colored cells, communication patterns between the robots, robot's internal variables, etc.) is projected on the arena and robots in real-time. 

Additional information

Tangible Swarm is a tool developed to complement the Blockchain: a new framework for swarm robotic systems research project. Detailed information about the system setup as well as configuration parameters can be found in the supplementary material of the paper titled "Secure and secret cooperation in robotic swarms".