IR Interrupt

In an IR interrupt existence sensor, the photo transistor is placed on wings that glide over the top of walls, while the IrED is typically placed at the lower part of the main robot chassis. This way, if a wall exists, it blocks the light path and the robot knows a wall exists.

The best feature of an interrupt existence sensor is the robustness. It is immune to vibration of the sensor banks. Even better, an interrupt sensor has much more time to catch a wall compared to a reflective sensor. This is because a reflective sensor passes the top of a wall (perpendicular to direction of motion) quickly and only has a few samples to it. An interrupt sensor, however, remains interrupted as long as the wall exists.

Interrupt sensors are not with their problems, however. Reflective sensors are easy to interpret because they sense the existence of a wall immediately under them. Interrupt sensors, however, sense the existence of a wall that simple blocks the light path. It takes some more logic to translate the sensor readings to the location of walls.

Interrupt sensors are best suited for detecting a front wall because they are robust for walls that are perpendicular to the direction of motion. Interrupt sensors are typically useless for detection walls that are not immediately around the robot.