How to detect if a nearby parked car has started engine?

Question

We have a project with a machine servicing a car parked next to it. It's comparable to a car washning machine.

Before the machine is started, we need to be 100% sure that the engine is off. Also, if we detect that the engine is turned on during the process (which takes severa minutes), the machine should withdraw its operation immediall, to avoid damages.

The machine is supposed to refuel the car without any manual action by the driver.

Electrical cars are not a part of our current plan. But it certainly is relevant that some cars stop the engine when the brake is down.

Our problem is to detect whether the car parked at the machine is running or not. We have already been thinking of these solutions:

1. Microphone listening for engine sound. Problem: In a noisy environment, we might have too many false alerts, when a big truck is parking close nearby.

2. IR camera looking for hot exhaust gas. Problem: We have tried that and can't see any significant changes whether the engine is on or not

3. Camera detecting whether the engine lights are on. Problem: Not all cars have lights on when engine is running. Not all cars require the driver to push the brake to start the engine.

What other options do you see for us?

Answer 1

This sounds like an XY problem.

Your problem is you need to prevent damage to your equipment. Your rabbit-hole solution is to assume that you need to retract your equipment when the vehicle begins to drive. You are myopically focused on detecting when the vehicle begins moving.

Instead, I propose you prevent the vehicle from moving. An electric or hydraulic bollard is cheap ($2000-3000) and designed from both a mechanical and visual perspective that a car needs to stay put.

Give the user a flashy screen, like a car wash. Show them the status, gallons filled, estimated time remaining. Retract the bollard after your robot's sensitive bits have tucked themselves away, then change the screen to a big friendly "you're done!".

Answer 2

Definitely sounds like an XY problem, you don't need to detect whether the engine is running, you need the car not to move.

Bryan's idea made me think of one that I think is even better, as there is no risk of damage to the car, if someone were to run into the bollard when it is up.

Mount rollers in the ground (parallel to the direction of travel) that are normally locked (preventing them from rolling), allowing them to be driven on. When your apparatus is engaged, unlock the rollers, thus preventing the car from driving away even if the engine is started and the driver attempts to drive. When done, and the device is retracted, lock the rollers again.

Answer 3

Most Petrol Cars can be heard on a sensitive AM radio .Most of the electrical noise comes from the spark plugs .You can try using a regular MW AM radio to start experimenting with .If you are close to the car like feet away you should hear something .Better would be a SW radio if you can get your hands on one .It has been said that car ignition noise has a very broad peak around 20 to 40 MHz .If you can hear something from your experiments then you could process the Audio with a DSP .Electric cars do make engine noise too .I can hear my Nissan leaf on my experimental MW AM car radios when I use an external test Antenna and plug them into the Standard 12V Cig lighter plug .The sensitivity of these test car radios is good but not excellent .This means that you wont need some really expensive comms radio to achieve this . I was told in 1974 by my father who was a Civil Engineer who worked for the city council that the traffic light signalling in Dunedin where I grew up detected cars by antenna wires buried under the road .Diesel cars were rare then but large trucks were diesel .I do not know how well thier system worked .

Answer 4

Laser "microphone" vibration detection. Can be done invisibly with IR lasers. All you need to do is point it at a piece of bodywork and look for vibrations in the range of engine RPM with suitable magnitude. You'll need to calibrate it so the vibrations of passengers moving around or loud sound systems don't trigger it.

You can also detect vibration at a distance with doppler ultrasound, but I think this is harder. http://ieeexplore.ieee.org/document/1293292/

With electric cars I think this may be impossible; but there may also be ways of wirelessly contacting the car's control electronics to monitor this.

Note that existing fuelling stations handle the risk of people driving off with the hose attached - if this does happen it breaks off in a safe-ish manner and you charge the driver's insurance.

Answer 5

Exhaust pipe detection requires a Flir or IR THERMAL camera, not an IR security camera. Thermal cameras are far more pricey, use exotic lenses (germanium, chalcogenide, etc.) and they see IR longwave, not the shorter near-visible wavelengths.

There are even thermal cameras with narrow filters tuned to CO2, and can see the gas itself rather than the high-temp emissions. "Gas FindIR" product from Flir corp.

Cheaper might be a handful of IR thermometers, pointed to various locations where you'd expect to find the exhaust outlet. Experiment with those $12 Harbor Freight keychain thermal IR detectors.

Answer 6

OBD

You should be able to find ready to use hardware and possibly software libraries too, or you could write your own.

Make it a prerequisite to have your OBD hardware plugged into your Vehicle. Only when you have established that Vehicle engine is dead, should you start remainder of service process. OBD will also allow you to sense if/when engine comes to life.

And it will cover a vast majority of current vehicles.

Answer 7

I would go with a nitrogen and carbon dioxide detector on the exhaust pipe. The gas will start coming out the pipe the moment the engine starts. Don't count on heat as it might take a couple of second for the whole area to heat up especially on a cold day, same goes for the hat of the gas. If you have a system that finds the fuel opening you wont have any difficulties finding the exhaust pipe.