Display Swarm

Paul Beardsley (Disney Research, Zurich)
Javier Alonso Mora (ETH Zurich and Disney Research, Zurich)
Andreas Breitenmoser (ETH Zurich)
Martin Rufli (ETH Zurich)
Prof. Dr. Roland Siegwart (ETH Zurich)

Display Swarm is a new kind of display composed of a mobile robot swarm. Each robot acts as an individual pixel and has controllable color. We use the swarm to make representational images and animated movies.

Our first prototype system had 14 robots, sufficient to generate basic graphics and providing a test-bed for research on robot collision avoidance and localization. This research also addressed the unusual requirement of achieving visually appealing motion of the robots. The latest prototype system has 75 robots, with magnetic wheels for deployment on a vertical surface to provide better visibility.

Swarm images are a novel concept that raises basic questions about how to best represent an image with a finite number of movable pixels, and current research is investigating swarm graphics and interaction.

“Reciprocal Collision Avoidance for Multiple Car-like Robots”, J. Alonso-Mora, A. Breitenmoser, P. Beardsley, R. Siegwart, IEEE International Conference on Robotics and Automation (ICRA), May 2012.

In this paper a method for distributed reciprocal collision avoidance among multiple non-holonomic robots with bike kinematics is presented. The proposed algorithm, bicycle reciprocal collision avoidance (B-ORCA), builds on the concept of optimal reciprocal collision avoidance (ORCA) for holonomic robots but furthermore guarantees collision-free motions under the kinematic constraints of car-like vehicles. The underlying principle of the B-ORCA algorithm applies more generally to other kinematic models, as it combines velocity obstacles with generic tracking control. The theoretical results on collision avoidance are validated by several simulation experiments between multiple car-like robots.

Paper [PDF, 1.2MB] [BiBTeX]
Movie [see embedded link below]

“DisplaySwarm: A robot swarm displaying images”, J. Alonso-Mora, A. Breitenmoser, M. Rufli, S. Haag, G. Caprari, R. Siegwart, P. Beardsley, IEEE/RSJ Int. Conf. on Intelligent Robots and Systems, Symposium: Robot Demonstrations, October 2011.

DisplaySwarm is a swarm of mobile robots that represents images in a novel way and further proves concepts on reciprocal collision avoidance in cluttered environments and complex pattern formation. Each robot pixel is a small circle in shape, with controllable colored illumination using LEDs that glow under the translucent upper surface. The robots change position and color to represent both abstract patterns and representational images. Viewers react in an entirely different way than looking at a screen – our experience has been that people judge the robots to have personality, literally bringing emotion into the picture.

Paper [PDF, 164KB] [BiBTeX]

“Multi-Robot System for Artistic Pattern Formation”, J. Alonso-Mora, A. Breitenmoser, M. Rufli, R. Siegwart, P. Beardsley, Proc. of IEEE Int. Conf. on Robotics and Automation, May 2011.

This paper describes work on multi-robot pattern formation. Arbitrary target patterns are represented with an optimal robot deployment, using a method that is independent of the number of robots. Furthermore, the trajectories are visually appealing in the sense of being smooth, oscillation free, and showing fast convergence. A distributed controller guarantees collision free trajectories while taking into account the kinematics of differentially driven robots. Experimental results are provided for a representative set of patterns, for a swarm of up to ten physical robots, and for fifty virtual robots in simulation.

Paper [PDF, 946KB] [BiBTeX]
Movie [see embedded link below]

“Optimal Reciprocal Collision Avoidance for Multiple Non-Holonomic Robots”, J. Alonso-Mora, A. Breitenmoser, M. Rufli, P. Beardsley, R. Siegwart, Proc. of the 10th Int. Symp. on Distributed Autonomous Robotic Systems, November 2010.

In this paper an optimal method for distributed collision avoidance among multiple non-holonomic robots is presented in theory and experiments. Non-holonomic optimal reciprocal collision avoidance (NH-ORCA) builds on the concepts introduced in [2], but further guarantees smooth and collision-free motions under non-holonomic constraints. Optimal control inputs and constraints in velocity space are formally derived for the non-holonomic robots. The theoretical results are validated in several collision avoidance experiments with up to fourteen e-puck robots set on collision course. Even in scenarios with very crowded situations, NH-ORCA showed to be collision-free for all times.

Paper [PDF, 1.8MB] [BiBTeX]
Movie [see embedded link below]

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