ACC/Pilot Assist Modification precautions

[afranke]

Sorry if this has been covered (I searched and couldn't find), but when it comes to ACC do we actually know what the "levels" mean?  I'll admit at one point I just upped all the PA/ACC stuff (on my '23 V60 PE) to whatever the highest level is for awhile.  It worked just fine, no errors and hundreds of miles without incident.  I recently reverted the config to stock to get service and used the ACC on the way, and it felt "better". I can't really describe how, just more situated.  I think there was less hunting between the lines, it seemed to actually follow closer, and the braking seemed smoother.

That got me thinking of possible reasons.  One idea that stuck out in my head is that maybe the "levels" are related to the size of the vehicle for PA/ACC calculations.  I wonder if by changing to a higher level I made the system think it was a different sized model.  This could cause issues with lane hunting as the software doesn't know the car isn't as wide as it thinks it is, so it's constantly trying to "fill" the middle of the lane with the wrong sized car.  On top, the following distance would probably be increased for a heavier vehicle as it would take longer to come to a complete stop.

I wish I could browse all of the default config data Orbit has pulled from cars to compare and see if there is a trend or "default" collection of settings for certain features or models.

I think you raise some very good questions and I would be interested to learn more on the lane keep and ACC values as well. Not sure about the theory on lane centering as the center of the lane doesn't change with the size of the vehicle but braking and following distance certainly could. I have played with the different levels of Pilot Assist and have not found a difference, they all want to bias to the left for whatever reason; so I always feel too close to the center in heavy traffic.

It's obviously all just made up in my head without seeing any code, but I've been debugging/troubleshooting software for 20+ years so I don't mind making some guesses about the logic they used.  Its possible they aren't actually looking to find the center of the lane, but to keep the car a certain distance from the lines on the edges (probably trying to keep the gap on each side about the same).  If this is the case, the system would need to "know" how wide the car is supposed to be in order to determine that gap.  If it has the wrong size, it'll end up in the wrong spot over and over, thus the hunting between lines. 

The systems these days use data from many sensors such as the camera, LIDAR, radar, as well as computer vision.  I do believe this is how the Volvo system works, and as with every other system they have in place, it must be modular to work across model lines.  Therefore, there must be some value passed to the ACC system that tells it how big the car is and where the sensors are in relation to each other.  This would definitely cause a problem as most ACC systems first use the camera to do edge detection for lines, which factors in camera perspective, which is different for vehicles of different heights.  Here's a basic outline from Wikipedia: https://commons.wikimedia.org/wiki/File:...orithm.jpg

And as I mentioned before, things like weight distribution and power are important details when automating a car.  How do we know there isn't some value here changing the maximum brake force applied or estimated stopping time/distance for an XC90 vs C40?  I wouldn't want to be behind the wheel (or driving in front of) an XC90 in ACC that thinks it's a C40 in ACC.

I dunno, just seems not worth the changes unless you know for sure they are adding a benefit.  I'll keep the Curve Speed Assist because I have actually seen it work and add benefit compared to what it was before.