It's raining it's pouring...

[MartyL]

How does the car know?

 

[Uncle Paul]

It's pretty smart.

Most likely camera sees raindrops on the windshield.

 

[MartyL]

Sounds right.

 

[Travis Denardo]

What about you pre-AP cars?

 

[Derek Kessler]

What about you pre-AP cars?

Pre-AP and AP1 work the same as any older car with rain-sensing wipers: an infrared sensor picks up decreased IR light reflected of the inside of the window because the raindrops defract the light.

 

[Travis Denardo]

Pre-AP and AP1 work the same as any older car with rain-sensing wipers: an infrared sensor picks up decreased IR light reflected of the inside of the window because the raindrops defract the light.

That’s awesome. Where is the IR sensor on those cars? At the top of the windshield?

What is AP2 & higher doing? Using the cameras?

 

[Derek Kessler]

That’s awesome. Where is the IR sensor on those cars? At the top of the windshield?

What is AP2 & higher doing? Using the cameras?

Typically, yes, the sensor was stuck top-center of the windshield by the mirror.

AP2 cars ditched that sensor in favor of using the cameras to gauge how much water is on the window. Hope exactly it determines that isn't clear — both because Tesla hasn't told us and machine learning of this type is by its very nature opaque. I suspect that it's looking for the telltale signs of light distortion, since it seems to fire less often if there's not a strong light source (such as headlights or a street light) hitting the water-covered windshield.