Distance sensor calibration

[John56]

Recently acquired 2018 Model S 100D.

I'm trying to get to trust the distance sensors on the front of the car. I pull into my garage to park the car. There is a concrete wall straight ahead with a bicycle against the wall. I've put a parking block in to stop the left front tire. As I approach the wall, the sensors show 30" - 25" - 18" - 15" when the tire contacts the block. The display says "STOP".

I measure the distance from the front bumper to the bike and it is about 15" (not including the bike pedal which is about 10" from the front bumper).

So I ran an experiment in my driveway: I lined up 3x cardboard file boxes and approached with the front bumper. The display shows 30" and then goes to the TPMS display showing an overhead view of the car with the tire pressure display next to each tire. I get no other information until the bumper is contacting the boxes.

It also doesn't seem to detect curbs which might be 6" high.

How can I trust the sensors to give accurate information when I pull into a parking space?

Thanks - John - Lafayette, Colorado.

 

[DerbyDave]

On my 2020, it seems to work similarly to yours. It does not detect curb blocks. You need to practice pulling into a parking space and stopping before the curb. Also, since the air suspension may lower over time, you really shouldn't pull up to touch the curb with a tire, you need to stop before the bottom lip of the front bumper goes over the curb block. My driveway entryway/curb is about 4" high, and slopes to allow my car to drive over it across my driveway. I am so happy the sensors do not pick up going over that curb. The sesnors seem to be very accurate for what they are designed to detect, like warning before you hit the garage wall, or another car.

I will say that reversing into a parking spot at walmart, I got now warning (visual, audible, or braking) before hitting the walmart 3" concrete bollard with a Walmart PickUp sign and another sign with phone number. I have learned not to entirely trust the car on any of its automated features. Hopefully it will catch things I do not see.

 

[John56]

I tried the cardboard boxes because if I did hit them - no big deal. But - I think the front bumper sensors may be ultrasonic and the cardboard may be transparent to the sensors. I should try it again with just a bicycle parked crossways in front of the car and see if the inch display corresponds to the actual measured distance.

Thanks

 

[vcor]

Cars with ultrasonic sensors like your 2018 S (and other makes too) have a cone of detection out of each of the 6 sensors (6 in front, 6 in back). They work on sound waves, so things like thin poles and curbs will not be seen. Not sure about cardboard boxes - likely cardboard is good at absorbing the sound and is not seen. Ultrasonic sensors really work best when they have a hard sound-reflective surface such as another car or a wall. Beyond that, you may be expecting way too much trying to detect a bicycle or small items like a pedal sticking out towards the car. You have to use some judgment and not blindly assume the sensors are going to see everything.

There is a calibration process, but I've never heard of anyone needing to do it unless they are replacing a sensor.

 

[vcor]

I didn't really answer your question. You can go into service mode and calibrate the USS sensors. Here's how you get into service mode: Service Mode – TeslaTap

Go to Driver Assist, and Sensors (photos in the article). Select "Program USS". I've not done a program myself, so I don't know what additional items you may need and/or how it might be screwed up if you don't know what you're doing. I tend to leave things that work alone.

 

[John56]

OK - thanks. I think that I will just experiment with it and see if I can determine if 15" is really 15" and under what circumstances.

Thanks for the info.