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Roof racks and ESP

6K views 28 replies 12 participants last post by  BigBang 
#1 ·
With the original roof racks and the roof box (Thule Motion XT) , is there a change in the operating mode of the ESP system due to the raised center of gravity of the vehicle?
I not found this information anywhere
 
#3 ·
Esp should work as it should regardless of the car's condition, it will intervene according to the parameters set into it such as steering angle vs. Slide/yaw...
Thanks for the answer, I know how the ESP works, but how ESP can detect that it has a cargo box on the roof
There must be some sensor that gives this information
 
#5 ·
Audi uses it in its Q models since 2009

Roof Rack Detection System

The roof rack detection system in the Audi Q5 is directly linked to the Electronic Stabilization Program (ESP®) control unit. When the crossbars are installed, a signal is sent that adjusts driving-dynamic relevant parameters according to the center of gravity. When the crossbars are not installed, the ESP® program adjusts dynamics to allow for more enthusiastic driving.
 

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#14 ·
Accelerometers and accelerator sensors are different things. Accelerometers measure things like pitch, roll, and yaw rates, and are most definitely used in the stability control system. When it comes to measuring roll rate, the onboard computers don't care where the CG is. It is simply too variable and quite literally changes as you drive (fuel burn). Thus, the stability control system only cares about the rate at which the vehicle is rolling, yawing, etc... and then it seeks to correct that. As for the Audi system, when it detects load bars, it reverts to an ultra conservative setting, thus allowing lower roll rates prior to intervention. Without knowing the parameters and baselines for each company's systems it would be impossible to say which was "safer" as Volvo's baseline could be more conservative than Audi's from the beginning.
 
#22 ·
No one has made the perfect car in the world, but in the category of expensive cars so many problems and stupid solutions is really a lot
For more than a year, Volvo's programmers are working to solve the problem, is that normal for you?
 
#23 · (Edited)
It's likely that the added mass on the roof will have only minimal impact on the handling characteristics of such a large/heavy car. It is limited to 100Kg I think anyway.

Sure, Audi went crazy and decided to add in a calculation based on roof racks being used. Great. Does any other manufacturer do that? Is there proven evidence it helps?

Just because Audi went down some rabbit hole for a 2% difference is some variable doesn't mean that it's worth it or that it matters much.

Most of the digital systems shouldn't care too much about where the weight of the car is.
Things like vehicle yaw/pitch/roll (which are measured by several accelerometers) may be affected by the additional weight (minimally), but the final result as measured by the sensor, is still accurate.

Or to put it another way... an accelerometer in a Miata or school bus, still measures the final resultant force on the whole system. The measured value may vary, but it's still accurate as a measure of the forces acting on the overall system it's physically attached to.

Even things like the roll-over prevention system shouldn't much care about the weight on the roof. Yes, it's more likely to roll with a higher center of gravity, but if the sensor is looking for X% of movement in X plane as an indication to a roll-over event, that reading won't be changed by the mass of the vehicle.

I'm sure there's a slight difference, mostly due to the added wind resistance I'd guess, but it's not really something I'd worry about, especially as you should be driving more slowly and careful with a roof-mounted load regardless.
 
#29 · (Edited)
Roof racks for the model 2009-2016 were part of the serial equipment of all models, now it's only for the SQ5 series and for others model Q5 is extras equipment

The price is 258 EUR in Germany or 218 EUR without tax , it's not 3-4 times as expensive as you write, price for Volvo is 230 EUR

Yes, I bought it for the new Q5 2018, and in 2010 I got it as standard equipment

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