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Establishing Spatially Targeted Communication in a Heterogeneous Robot Swarm |
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Nithin Mathews,
Anders Christensen,
Eliseo Ferrante,
Rehan O'Grady and
Marco Dorigo
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Abstract
We consider a heterogeneous swarm of aerial robots and wheeled robots. We present a system that enables spatially targeted communication
without relying on any form of global information. Our system allows an aerial robot to establish a dedicated communication link with individual
wheeled robots or with selected groups of wheeled robots based on their position in the environment. We show how a spatially targeted one-to-one
communication link can be established using a simple LED and camera based communication modality. We provide a probabilistic model of our approach to
derive an upper bound on the average time required for establishing communication. We show in simulation- based experiments that our approach scales
well. Furthermore, we show how our approach can be extended to establish a spatially targeted one-to-many communication link between an aerial robot
and a specific number of co-located wheeled robots. The heterogeneous swarm robotic hardware is currently under development. We therefore demonstrate
the proposed approach on an existing multirobot system consisting of only wheeled robots by letting one of the wheeled robots assume the role of the
aerial robot.
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One-to-one Communication
Simulation 1: 10 wheeled robots, 2 colors in the selection process, 4
iterations |
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This video footage shows the simulation-based experimental setup discussed in the paper. This particular simulation starts with an aerial robot
placed in the center of a closed, obstacle-free arena (2m x 2m) at a height of 2m. Ten wheeled robots are randomly placed within the visual
range of this aerial robot. The aerial robot is able to perceive all wheeled robots within the arena and vice versa. A total of 3 colors (red,
green and blue) are available to both the aerial robot and the wheeled robots. The color red is used to initiate and confirm the termination of
the process. The colors green and blue are used in the selection process. For the sake of better visibility, the colors displayed on the LEDs
are reinforced on the ground.
In the following, we provide further video footage of the simulation-based experiments carried out to test the scalability of our approach. In
the case of six colors in the selection process, the colors green, blue, yellow, cyan, violet and white are used.
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Experiment 1: 4 wheeled robots, 2 colors in the selection process, 4 iterations |
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This is the video footage of the real robot experiment described in the paper. The s-bot on the bottom assumes the role of the aerial robot and
establishes a one-to-one communication link with the s-bot on the top-left. A total of 3 colors (red, green and blue) are used in the control
program. The color red is used to initiate and confirm the termination of the process. The colors green and blue are used in the selection
process. The selection process is iterated four times before a one-to-one communication link is successfully established.
In the following, we provide further video footage of similar proof-of-concept experiments. The number of wheeled robots is kept constant at 4
and the number of colors in the selection process at constant 2. Also listed is the number of iterations of the selection process.
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One-to-many Communication
Simulation 1: Group size 10, approximate growth, 2 iterations, 14
excess robots |
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This video footage shows the simulation-based experiments explained in the paper. The simulation starts with an aerial robot placed in the
center of a closed, obstacle-free arena (2m x 2m) at a height of 2m. Eighty wheeled robots are randomly placed within the visual range of this
aerial robot. The aerial robot is able to perceive all wheeled robots within the arena and vice versa. Furthermore, the wheeled robots are now
able to perceive neighboring wheeled robots within a radius of 1m. Six colors are used in the selection process while establishing the
one-to-one communication link. For the sake of better visibility, the colors displayed on the LEDs are reinforced on the ground. In a first
phase, the footage shows how a one-to-one communication link is established to a particular wheeled robot. In a second phase, this one-to-one
communication link is extended (or grown) to a one-to-many communication link to include a minimum of 10 robots. This is achieved within 2
iterations including an excess of 14 robots.
In the following, we provide further video footage of the two types of simulation-based experiments we ran on the establishment of one-to-many
communication: (1) an exact group size is required, and (2) the final number of robots in the group is allowed to exceed the number of robots
initially desired. In the second case (approximate growth), also the number of excess robots is listed.
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Experiment 1: Group size 2, exact growth, 1 iteration |
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This is the video footage of the real robot experiment described in the paper. We placed 4 s-bots in the shape of an arch around a
predesignated s-bot which assumes the role of the aerial robot and seeks to grow a group of size 2. In a first phase, a one-to-one
communication link is established to the rightmost s-bot. In a second phase, this communication link is expanded to become a one-to-many
communication link including the second s-bot from the right.
In the following we provide further video footage of similar proof-of-concept experiments, in which the group size is varied between 2 and 3.
Also listed is the number of iteratons.
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