Robot Swarmish LEDs

Each robot has a red, green, and blue LED on top that can be programmed to blink in several patterns. This is the primary behavior-level debugging interface on the robots. Patterns that use one LED alone or all the LEDs together seem to work best, as patterns involving multiple lights communicating independent information can be difficult to read quickly.

It has settled on two intensities, bright and dim, and two wave patterns, a square wave and semi-sinusoidal wave. The two patterns are only distinguishable at lower frequencies, which give us 12 distinct single-LED patterns that can be read by an experienced user. The absolute minimum time to read square patterns is ½ the period of the second-lowest frequencies, which are 533 milliseconds.

The semi-sinusoidal patterns can be read slightly faster because the user can infer the frequency from the slope. Besides the square and semi-sinusoidal patterns from above, the four all-LED patterns also include two patterns that cycle back and forth through all the lights, either with smooth or sharp transitions.

All these variations produce 108 common patterns, each of which can be read in about 1.2 second. In an actual application, similar behaviors and states are grouped into single colors, leaving many patterns unused.