How can I detect whether driver is sitting in car or not?

[rushi121]

I want a device that can either stick on dashboard or like a key fob in driver pocket that will help to detect whether person is in car or not.

Requirements:
- Device must have a detector and siren. When detector detects that person is not in car should buzz siren.
- Can be a device in car or in person's pocket
- Low cost and small form factor

Solutions I can think of (please validate my understanding)
1. PIR Motion Sensor stuck on dashboard
- Cons: The person need to keep moving

2. Accelometer and Gyroscope
- Is it possible to detect whether person is walking using these sensors?

3. RFID?

4. Beacons?
- Cons: Need a phone?

What technology does smart keys for car use?

 

[DrClaude]

My car has pressure sensors in the seat to detect when someone is sitting. It can get very annoying if I put a bag in the passenger seat and get a beeping warning that the passenger seat belt is not buckled

Edit: Before anyone comments, yes, I know that it is dangerous to have heavy objects loose in the car.

 

[gjonesy]

DrClaude has a reasonable solution, a load cell in the seat would work. But you would have connect it to a recording device that would buzz when there is no load/weigh. Most modern cars use a similar technology to turn on and off passenger airbags. The problem would be finding the equipment that would "buzz" I suppose if you could find a recording device it could be rigged to buzz when the circuit on the load cell was open. You just need someone that knows something about electronics to build it.

 

[anorlunda]

Do you know that RFID is already used to detect if the car's key is nearby?

Micro-switches can also be used like load cells. A micro switch can connect 12 v to a buzzer with no additional electronics. But it needs to be in the seat, not on the dashboard.

My favorite was some car in the 90s. It had fingers to feel your fanny to identify who was sitting there. It used that information to set your personal profile suite of settings like radio stations, temperature, and seat position. It would be much simpler to do that today using your phone automatically connects to the car with Bluetooth.

 

[russ_watters]

1. PIR Motion Sensor stuck on dashboard
- Cons: The person need to keep moving

The term "motion sensor" is somewhat obsolete: Google "occupancy sensor". Modern ones use other technologies such as ultrasonics, which can map out a room and detect occupancy without motion.

 

[newjerseyrunner]

An IR camera with facial recognition?