Better hygiene through better sensing (TM).

Passive infrared motion sensor array for automatic flush with contraband and terrorist activity detection

EXISTech's Passive InfraRed (PIR) motion sensor may be used to automate multiple fixtures, such as multiple automatic doors, lighting, HVAC, or plumbing fixtures.

This application note describes the automation of two toilets, for conversion to sensor operated automatic flush.

A single sensor can control multiple toilets. In this application note, one sensor is used to control two toilets. The sensor is ceiling-mounted, directly above the partition between the two stalls. One sensor is needed for each two toilets. One sensor can also control several urinals.

CFAR (Constant False Alarm Rate) triggering

Moreover, the use of EXISTech's PIR array (160 by 120) allows for an intelligent control system that will not be falsely triggered by, for example, a person changing clothes in the toilet stall:

Half flush versus full flush (water savings)

It can also distinguish the difference between urination:

and defecation:

so that it can use the appropriate amount of water to flush waste from the bowl (e.g. only a half-flush is required when only liquid waste is present).

The passive infrared (PIR) sensor can distinguish waste left in the bowl (e.g. note the bright areas in the bowl at left, from the warm urine) from other heat sources, such as thermal buttprints on the seat, and thermal footprints on the floor (at right) left by a barefoot user:

The PIR temperature sensor can also be used to prevent terrorism. Here the thermal signature of contraband being passed beneath the stall divider is detected automatically:
(Frame 2848)
(Frame 2850)
(Frame 2876)

You can download a short time-lapse video (approx. 1.2 megabytes) showing the EXISTech passive infrared sensor in operation for the detection of contraband being passed beneath the stall divider (including the extracted frames from above).

Other criminal activity, such as failure to flush the toilet after use, can also be detected automatically. Here is a high speed capture of toilet usage with failure to flush. The temperature sensor can be used to either automate the flushing of the toilet ("automatic flush") or to simply detect failure to flush and notify the appropriate authorities.

EXISTech also has an intelligent sensor operated handwash faucet, as well as a sensor operated decontamination shower for processing victims of a terrorist attack.

Privacy (if such a concept is compatible with security, hygiene, and efficiency)...

See also ``Intelligent fixtures and systems'', S. Mann, ISAST LEONARDO, Vol. 36, No. 3, pp. 199-210, June 2003.