TPMS, how does it work? Reggie?
12-10-2010, 09:50 AM
#2
AudiWorld Expert
Audi is opting for the indirect route. That's right: indirect TPMS. Although the generation 1 approach didn't work, NIRA Dynamics, which didn't participate in that technology, has developed a software-based system that, explains Forssell, has sufficiently robust algorithms such that it can handle the NHTSA requirement of detecting 25% of tire pressure loss within 20 minutes while driving at a speed of 31 to 62 mph; the detection time is generally much faster than NHTSA's 20-minute requirement. There are no wheel-mounted battery-powered sensors. No radio frequency transmitters or receivers. Rather, the NIRA Dynamics system, designated TPI (for "Tire Pressure Indicator"), makes use of the wheel speed sensors that are part of the antilock braking system (ABS) and electronic stability control system (ESC). A processor is needed as well.
"Wheel speed sensors have been around since the introduction of ABS, and have proven to be mature, stable and reliable," Forssell says. They are used as input to the NIRA Dynamics software. At first, the processor that will make the calculations is a stand-alone system. For example for the '09 Audi A6, there will be what Roscher describes as a "little gray box." That's the processor. "Eventually," he says, "it will be integrated into the ESC processor." It is simply a matter, going forward, of making accommodations for the indirect TPMS system in the controller.
Essentially, the NIRA Dynamics TPI system "learns" the radii and frequency characteristics of properly inflated tires. Then, it is able to detect whether there are deviations from normal, which would be a result of the loss of tire pressure (e.g., when a tire loses pressure, there is a change in the radius as the tire rotates, which has a consequent effect on the measured parameters). The system can detect a change in any or all of the tires (remember that the previous indirect systems measured pairs of tires unlike this one, which has inputs from each of the tires).
Because there aren't additional sensors, there is less cost and complexity with this system, Roscher explains. He goes on to point out that there is a customer benefit because as this is a software-based system, when wheels or tires are changed, all the driver and/or tire dealer needs to do is recalibrate the system (this essentially consists of selecting a reset function, then driving the car with properly inflated tires—period). Forssell adds, "You can change and even supersize your tires and the system will learn about them."
According to Forssell, Audi is the first vehicle manufacturer that is standardizing on this indirect TPMS system. It is anticipated that the full lineup of Audi vehicles will be equipped with the system by the 2011 model year.
12-10-2010, 09:51 AM
#3
12-10-2010, 09:53 AM
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12-10-2010, 10:43 AM
#6
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May I point out that the 2009 and early 2010 Q5 had the direct tire pressure monitoring system. The direct system is still more reliable in my opinion, but it is more costly and less convinient, but the indirect system's technology have advance quite a bit in recent years to the point where Audi and other car manufacturers feel more comfortable installing it their cars.
12-10-2010, 01:01 PM
#7
AudiWorld Senior Member
May I point out that the 2009 and early 2010 Q5 had the direct tire pressure monitoring system. The direct system is still more reliable in my opinion, but it is more costly and less convinient, but the indirect system's technology have advance quite a bit in recent years to the point where Audi and other car manufacturers feel more comfortable installing it their cars.
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02-04-2011, 09:07 AM
#8
AudiWorld Super User
Great insight. Related - In switching over to Winter rims/tires with a different circumference it appears a reset of the ABS-based TPMS is required. Is this automatically accomplished while subsequently driving or must it be done manually (and if the latter how so please). TIA (no manual as yet ...).
Here: http://www.autofieldguide.com/articles/040805.html
Audi is opting for the indirect route. That's right: indirect TPMS. Although the generation 1 approach didn't work, NIRA Dynamics, which didn't participate in that technology, has developed a software-based system that, explains Forssell, has sufficiently robust algorithms such that it can handle the NHTSA requirement of detecting 25% of tire pressure loss within 20 minutes while driving at a speed of 31 to 62 mph; the detection time is generally much faster than NHTSA's 20-minute requirement. There are no wheel-mounted battery-powered sensors. No radio frequency transmitters or receivers. Rather, the NIRA Dynamics system, designated TPI (for "Tire Pressure Indicator"), makes use of the wheel speed sensors that are part of the antilock braking system (ABS) and electronic stability control system (ESC). A processor is needed as well.
"Wheel speed sensors have been around since the introduction of ABS, and have proven to be mature, stable and reliable," Forssell says. They are used as input to the NIRA Dynamics software. At first, the processor that will make the calculations is a stand-alone system. For example for the '09 Audi A6, there will be what Roscher describes as a "little gray box." That's the processor. "Eventually," he says, "it will be integrated into the ESC processor." It is simply a matter, going forward, of making accommodations for the indirect TPMS system in the controller.
Essentially, the NIRA Dynamics TPI system "learns" the radii and frequency characteristics of properly inflated tires. Then, it is able to detect whether there are deviations from normal, which would be a result of the loss of tire pressure (e.g., when a tire loses pressure, there is a change in the radius as the tire rotates, which has a consequent effect on the measured parameters). The system can detect a change in any or all of the tires (remember that the previous indirect systems measured pairs of tires unlike this one, which has inputs from each of the tires).
Because there aren't additional sensors, there is less cost and complexity with this system, Roscher explains. He goes on to point out that there is a customer benefit because as this is a software-based system, when wheels or tires are changed, all the driver and/or tire dealer needs to do is recalibrate the system (this essentially consists of selecting a reset function, then driving the car with properly inflated tires—period). Forssell adds, "You can change and even supersize your tires and the system will learn about them."
According to Forssell, Audi is the first vehicle manufacturer that is standardizing on this indirect TPMS system. It is anticipated that the full lineup of Audi vehicles will be equipped with the system by the 2011 model year.
Audi is opting for the indirect route. That's right: indirect TPMS. Although the generation 1 approach didn't work, NIRA Dynamics, which didn't participate in that technology, has developed a software-based system that, explains Forssell, has sufficiently robust algorithms such that it can handle the NHTSA requirement of detecting 25% of tire pressure loss within 20 minutes while driving at a speed of 31 to 62 mph; the detection time is generally much faster than NHTSA's 20-minute requirement. There are no wheel-mounted battery-powered sensors. No radio frequency transmitters or receivers. Rather, the NIRA Dynamics system, designated TPI (for "Tire Pressure Indicator"), makes use of the wheel speed sensors that are part of the antilock braking system (ABS) and electronic stability control system (ESC). A processor is needed as well.
"Wheel speed sensors have been around since the introduction of ABS, and have proven to be mature, stable and reliable," Forssell says. They are used as input to the NIRA Dynamics software. At first, the processor that will make the calculations is a stand-alone system. For example for the '09 Audi A6, there will be what Roscher describes as a "little gray box." That's the processor. "Eventually," he says, "it will be integrated into the ESC processor." It is simply a matter, going forward, of making accommodations for the indirect TPMS system in the controller.
Essentially, the NIRA Dynamics TPI system "learns" the radii and frequency characteristics of properly inflated tires. Then, it is able to detect whether there are deviations from normal, which would be a result of the loss of tire pressure (e.g., when a tire loses pressure, there is a change in the radius as the tire rotates, which has a consequent effect on the measured parameters). The system can detect a change in any or all of the tires (remember that the previous indirect systems measured pairs of tires unlike this one, which has inputs from each of the tires).
Because there aren't additional sensors, there is less cost and complexity with this system, Roscher explains. He goes on to point out that there is a customer benefit because as this is a software-based system, when wheels or tires are changed, all the driver and/or tire dealer needs to do is recalibrate the system (this essentially consists of selecting a reset function, then driving the car with properly inflated tires—period). Forssell adds, "You can change and even supersize your tires and the system will learn about them."
According to Forssell, Audi is the first vehicle manufacturer that is standardizing on this indirect TPMS system. It is anticipated that the full lineup of Audi vehicles will be equipped with the system by the 2011 model year.
02-04-2011, 10:46 AM
#9
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In the car setup menu there is an option to reset the TPMS. You'd do it once your tires are properly inflated, and once you've driven for x minutes (I forget exactly how long), the system will then know your tires' properly inflated parameters.
02-04-2011, 01:13 PM
#10
AudiWorld Expert
Yep - thanks - and one needs to do this every time you swap wheels and tires.