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:
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.
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
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?