As in real cities, also in Roobopoli the intersections are managed by traffic lights.
In Roobopoli the traffic lights have only two colors, red and green, and are managed by a control unit.
The control unit is made with a Nucleo F401RE microcontroller board, which by means of a relay animates the traffic light cycle.
A simple implementation of traffic light management is available in the archive at the following link
The traffic light is always preceded by a road sign of the type shown in the following figure.
The blue color strip serves to ensure that the Roobokart is able to recognize the presence of the sign using the front IR sensor.
A black line follows along the entire width of the signal. This black line is used to align the Roobokart on the sign. This serves to make the cartel reading effective .
The passage from white to black of the lines to the right, causes the reading of the band on the left which may be white or black. In the first case it will encode a 0, in the second a 1.
The readings of the white or black bands occur through the side IR sensors.
Road signs, to be printed in color and pasted on the road can be downloaded here