## Distributed Control

The video clips above demonstrate a distributed coverage control
algorithm. The robots are meant to maintain coverage of the whole region
while collecting in greater concentration over areas where the light is
brighter. Robots in the left clip have been adjusted to be less sensitive
to the light than those in the right clip.

## Distributed Algorithm Design

The video clips below demonstrate dynamic task assignment on a small group of robots. The goal distribution is specified in terms of the percentage of red, green, and blue robots. This goal distribution is relayed to the swarm at run-time. All of the algorithms are robust to the removal or addition of robots at any time, which is critical for implementation in any real multi-robot system.

We considered four algorithms: Algorithm **Random-Choice** selects tasks randomly, but runs in constant time. Algorithm **Extreme-Comm** compiles a complete inventory of all the robots on every robot, runs quickly, but uses a great deal of communication. The **Card-Dealer's** algorithm assigns tasks to individual robots sequentially, using minimal communications but a great deal of time. The **Tree-Recolor** algorithm is a compromise between **Extreme-Comm** and **Card-Dealer's**, balancing communications use and running time.

#### Random-Choice Algorithm

DTA-RandomChoice.mpg

Algorithm **Random-Choice** is the simplest solution: robots choose a given task with probability equal to the relative size of that task subgroup in the target distribution. This algorithm requires no communication and completes immediately. However, there is a high probability that it will fail to achieve the target distribution in small to medium-sized swarms (10-50 robots).

#### Extreme-Comm Algorithm

DTA-ExtremeComms.mpg

In the **Extreme-Comm** Algorithm, each robot uses local interactions to build a complete list of all other robots in the swarm, and uses this list to determine its task. Though fast and accurate, the algorithm requires a large amount of inter-robot communications, and is impractical in all but the smallest groups.

#### The Card-Dealer's Algorithm

DTA-CardDealers.mpg

DTA-CardDealers (with physical sorting)

The **Card-Dealer's** algorithm uses minimal communications by sequentializing the task-assignment problem into a series of stages. The robots "count-off" to allocate tasks, and the algorithm requires a long execution time.

#### The Tree-Recolor Algorithm

DTA-TreeRecolor-01.mpg

Finally, the **Tree-Recolor** algorithm is a compromise between Extreme-Comm and Card-Dealer's, balancing communications use and running time by using gradient trees.

Research sponsored by Boeing