The IR Sensor serves as a safety mechanism to ensure that the door does not close when anything is in the doorway.

This relatively simple system is comprised of an IR LED and IR receiver. The two are oriented such that the emergency state will be triggered when objects break the line of sight between the LED and receiver.

The line of sight is oriented just in front of the door panel, parallel to the seam the doors make as they close. Given this orientation of the sensor, any object that is in the path of the closing doors will be pushed into the sight line before the doors ultimately close, automatically re-opening them until another input re-initiates the closing process.

A more detailed circuit diagram is represented in the electronics page

The black channel that surrounds the IR receiver sensor serves to limit what the sensor actually can see. A longer and narrower channel necessitates a precise alignment between the receiver and emitter, and a shorter, wider channel allows the receiver to view a broader channel of IR light, enabling a broader sensing zone in the doorway. The ideal configuration of sensor and emitter will be critical to the effectiveness of this sensor setup.

Currently, we need to recalibrate the sensor threshold for each room that we test the door in, because room lights emit varying wavelengths of IR light, which must be accounted for. In the case of 5Wits, we could see room lighting conditions during the transition between rooms as a potential challenge to work with while calibrating an IR system. With a more robust sensor, though, it seems like a feasible alternative for a tape switch, the current standard at 5Wits.

Given the fact that we successfully calibrated and recalibrated a simple configuration of a line of sight sensor, it seems like a feasible method for a safety mechanism to develop upon.