Speed Limit Detection
10-20-2020, 04:47 PM
#1
AudiWorld Member
Thread Starter
Speed Limit Detection
My 2019 Prestige has traffic sign (Speed limit) detection. I have not set any limits on overages. However, there is an off ramp on my commute that when buzzing along at 70 mph (the speed limit) the vehicle will suddenly flash that the speed limit is 30 mph (the exit ramp speed) and begin to slow the vehicle, even though I'm not exiting. I have to override the adaptive cruise by pressing the throttle after is applies the brakes, but I'm confused as to why it's even trying to slow me down, given I have no preset "overage" speed to keep me from exceeding. Is there a 'shadow' limit?
Thoughts on why I'm experiencing this?
Thoughts on why I'm experiencing this?
10-20-2020, 08:21 PM
#3
AudiWorld Member
There is a setting in the MMI for whether it will adjust the cruise set speed to speed limit signs. I forget exactly what the option is called, but you might have that enabled. I turned it off because the car would also slow way down for school zones, even if they weren’t activated.
The following users liked this post:
gestalt77 (10-21-2020)
10-21-2020, 07:23 AM
#5
AudiWorld Senior Member
This is definitely confusing. There are two separate settings and it's important to distinguish between them.
1) The first is Predictive Control (efficiency assist). This is a function of Adaptive Cruise. It is found at Driver assistance > Audi adaptive cruise control. There are two sub-functions: (A) Adaption to Route Ahead - this will slow you down as you approach turns and curves, and (B) Set Speed Limit - this will speed or slow the car based on detected speed limit. It is important to note that it ALWAYS uses the exact speed limit. There's no setting to allow it to cruise at, say, 10 mph over the speed limit. The "with tolerance" setting here only allows the Set Speed Limit function to vary a little bit above and below (mostly below) the detected speed limit for efficiency. I have Adaption to Route turned on (I like that how it slows for curves and turns), and Set Speed Limit set to off because I generally cruise a bit above the speed limit and so it doesn't slam on the brakes when it detects a non-applicable speed sign.
2) Traffic Sign Warning. This is NOT a function of (and has nothing to do with) Adaptive Cruise. It is found at Driver Assistance > Speed warning > Traffic sign warning. This lets you set a threshold above the detected speed limit, up to +10 mph. The ONLY thing this does is to cause the displayed speed limit sign on the instrument cluster (and HUD) to FLASH. That's it. That's all it does. I have this set to +10 so I get a visual reminder when I'm well over the speed limit. If you have this turned on and an exit speed limit sign is detected, the only effect will be a flashing indicator on the dash. The car will not automatically slow down.
Although these two systems both use the sign-detected speed limit as input, they really have nothing to do with each other.
1) The first is Predictive Control (efficiency assist). This is a function of Adaptive Cruise. It is found at Driver assistance > Audi adaptive cruise control. There are two sub-functions: (A) Adaption to Route Ahead - this will slow you down as you approach turns and curves, and (B) Set Speed Limit - this will speed or slow the car based on detected speed limit. It is important to note that it ALWAYS uses the exact speed limit. There's no setting to allow it to cruise at, say, 10 mph over the speed limit. The "with tolerance" setting here only allows the Set Speed Limit function to vary a little bit above and below (mostly below) the detected speed limit for efficiency. I have Adaption to Route turned on (I like that how it slows for curves and turns), and Set Speed Limit set to off because I generally cruise a bit above the speed limit and so it doesn't slam on the brakes when it detects a non-applicable speed sign.
2) Traffic Sign Warning. This is NOT a function of (and has nothing to do with) Adaptive Cruise. It is found at Driver Assistance > Speed warning > Traffic sign warning. This lets you set a threshold above the detected speed limit, up to +10 mph. The ONLY thing this does is to cause the displayed speed limit sign on the instrument cluster (and HUD) to FLASH. That's it. That's all it does. I have this set to +10 so I get a visual reminder when I'm well over the speed limit. If you have this turned on and an exit speed limit sign is detected, the only effect will be a flashing indicator on the dash. The car will not automatically slow down.
Although these two systems both use the sign-detected speed limit as input, they really have nothing to do with each other.
Last edited by RickObe; 10-21-2020 at 07:25 AM.
10-21-2020, 08:11 AM
#6
AudiWorld Super User
I found the speed limit setting with the predictive control was turned on by having the car brake hard when it detected a school zone on a rural road. 110 kmh to 30 was almost whiplash territory. It was on a weekend and there was no reason for the car to do that. I found the setting and turned off the speed limit.
10-21-2020, 10:21 AM
#7
That "Predictive Control" is an accident waiting to happen. I've had many instances where the car "sees," or thinks it sees a speed limit much lower than its going and it slams on the brakes. At least if they are going to have it, it needs an option to NOT use brakes. About 50% of the time its correct, some crazy traffic engineer lowered the speed for no reason, people ignore such things but the car doesn't. Another 50% of the time, the car sees a speed limit sign on an adjacent road, and misreads it. After turning the feature off, its so much better.
Trending Topics
10-21-2020, 03:08 PM
#8
AudiWorld Member
Thread Starter
Interesting, the place where this has happened (only place, actually) is on a very gentle turn on the interstate (speed limit 70mph) as it makes one of the 4 curves around the city (straight otherwise). You could go 120 mph through here with no fear (not that I would) but I wonder if the 'predictive control' is what is causing this, as it's seeing it as a turn (it's barely a turn).
10-21-2020, 03:14 PM
#9
Ultimate Keyboard Warrior
Interesting, the place where this has happened (only place, actually) is on a very gentle turn on the interstate (speed limit 70mph) as it makes one of the 4 curves around the city (straight otherwise). You could go 120 mph through here with no fear (not that I would) but I wonder if the 'predictive control' is what is causing this, as it's seeing it as a turn (it's barely a turn).
10-21-2020, 03:16 PM
#10
AudiWorld Member
Thread Starter
That "Predictive Control" is an accident waiting to happen. I've had many instances where the car "sees," or thinks it sees a speed limit much lower than its going and it slams on the brakes. At least if they are going to have it, it needs an option to NOT use brakes. About 50% of the time its correct, some crazy traffic engineer lowered the speed for no reason, people ignore such things but the car doesn't. Another 50% of the time, the car sees a speed limit sign on an adjacent road, and misreads it. After turning the feature off, its so much better.