Based on all the the "which tire" talk, check out new Mercedes low-pressure software. I am hoping to
05-25-2004, 08:38 AM
#1
AudiWorld Uber User
Thread Starter
Join Date: Jan 2001
Posts: 38,970
Likes: 0
Received 0 Likes
on
0 Posts
Based on all the the "which tire" talk, check out new Mercedes low-pressure software. I am hoping to
get a new SLK. On at least some they are offering an optional low tire pressure warning system. I assumed it was a pressure sensor on the inside of the wheel. But, as more info about the car trickles out, I have found that the low pressure warning system is software only. Sounds wacky, but what it does is use all the speed-yaw-steering input/accelerometer data from the ESP system and if it calculates that a tire is low it shows a warning. My question is, would the parameters change with different tires? Or even different compounds in the same tire? Given always changing friction coefficients on public roads, I just cannot understand how this works. Here is a blurb from Mercedes about the option:
"In the new version of the Mercedes-Benz Roadster, ESP® is also able to offer a further
function as an option which warns drivers of a loss of pressure in the tyres. ESP® constantly monitors the rotation speed of the wheels, which depends mainly on road speed, the vehicle load and the air pressure in the tyres. Because the ESP® Stability Program permanently records the wheel rotation speeds and compares the values with one another, it is able to detect any significant deviations in the readings. The control module also automatically checks other handling dynamics variables, such as lateral acceleration, yaw rate and wheel torque, in order to reliably diagnose a loss of air pressure in any one tyre. The system does not, however, measure the actual tyre air pressure. If the system detects that pressure is being lost in any of the tyres, a red warning appears in the cockpit's central display which reads 'Tyre pressure, check tyres.'"
"In the new version of the Mercedes-Benz Roadster, ESP® is also able to offer a further
function as an option which warns drivers of a loss of pressure in the tyres. ESP® constantly monitors the rotation speed of the wheels, which depends mainly on road speed, the vehicle load and the air pressure in the tyres. Because the ESP® Stability Program permanently records the wheel rotation speeds and compares the values with one another, it is able to detect any significant deviations in the readings. The control module also automatically checks other handling dynamics variables, such as lateral acceleration, yaw rate and wheel torque, in order to reliably diagnose a loss of air pressure in any one tyre. The system does not, however, measure the actual tyre air pressure. If the system detects that pressure is being lost in any of the tyres, a red warning appears in the cockpit's central display which reads 'Tyre pressure, check tyres.'"
05-25-2004, 09:07 AM
#2
AudiWorld Super User
Join Date: Sep 2002
Posts: 14,586
Likes: 0
Received 0 Likes
on
0 Posts
It would be able to detect differential imbalances while cross-checking that to the yaw values. My
guess is that as a tire goes down, it changes the rolling radius vs the tire on the opposite side. So, if the computer is seeing different rates for the 2 front wheels lets say, and it cross check that with the yaw sensor and it doesn't see that you are in a turn -- it would activate the warning lamp.
05-25-2004, 09:16 AM
#3
AudiWorld Uber User
Thread Starter
Join Date: Jan 2001
Posts: 38,970
Likes: 0
Received 0 Likes
on
0 Posts
I think you are correct that that the radius is the dominant data point. Easy to compare in
straight line driving. Perhaps the other inputs are not even needed.
Thread
Thread Starter
Forum
Replies
Last Post
HoustonA5
Audi A5 / S5 / RS5 Coupe & Cabrio (B8)
4
07-07-2019 03:01 PM
snagitseven
A4 (B8 Platform) Discussion
13
09-23-2008 12:45 PM