Occupancy Sensor Capability

[benfrancis]

From WebThingsIO/gateway#3223: As a user I want to see the status of an occupancy sensor so I know whether there is a person in a room, even if they are not moving.

We have a capability schema for motion sensors but occupancy sensors are slightly different. Some motion sensors report motion and occupancy separately.

[benfrancis]

In WebThingsIO/gateway#3223 (comment) @flatsiedatsie mentioned that some presence sensors also provide some kind of range estimate for the distance of a person from the sensor. This could be another property type of a motion or occupancy sensor, or a separate capability. How best to model it?

I think there are various types of sensors out there and some of the names are used interchangeably but may be subtly different:

• Occupancy sensors: Aim to decide whether a room is occupied (e.g. PIR sensor), may miss someone sitting very still
• Presence sensors: Aim to detect a person even when stationary (e.g. ultrasonic, radar (mmWave), or camera)
• Proximity sensors: Binary near/not near for an object which is very close (e.g. capacitive, inductive (for metal), reflective IR)
• Distance sensor: Aims to measure exactly how far away an object is (e.g. Ultrasonic, ToF IR, LiDAR)

I think occupancy/presence sensors basically aim to measure the same thing (whether a person is there), but proximity sensors are a binary state for very close objects and distance sensors aim to measure a distance numerically.

[benfrancis]

Proposal...

Capabilities

OccupancySensor

Properties

Type	Read-only	Required
OccupiedProperty	Yes	Yes

DistanceSensor

Properties

Type	Read-only	Required
DistanceProperty	Yes	Yes

Properties

OccupiedProperty

• type: boolean

DistanceProperty

• type: number
• unit: meter

These two capabilities could be mixed and matched for an occupancy/presence sensor which can also measure distance.

[flatsiedatsie]

Note that the screenshot I showed has the range estimate as a string/enum, and not a number. The particular device allows you to set the range 'areas' and their sensitivy, and based on that the sensor will output if the distance is small, medium or large.

[flatsiedatsie]

Just a quick sketch for a capability that would indicate distance of the detected person. Obviously this design is bad, and would not even fit.