Encoder count changes due to wheel diameter

[leitmotif]

Let us ensure we quote all the facts
"Another option is to install an indirect tire pressure monitoring system that would warn the driver when a single tire has lost at least 25% of its inflation pressure compared to other tires on the vehicle. While direct systems could offer more precise warning thresholds, indirect systems cannot offer the same information or accuracy"

At 75% inflated (25% loss) that correlates to 24 psi on a 32 psi tire. Not only is that tire going to run hot I would not be surprised if it did not have a change in circumferance. Would not be surprised at it catching fire possibly

I think all the previous discussions assumed correct inflation pressure - for sure the research did - they ran the tires to warm them before they did the testing to check for differance in circumferance.
Dan Bentler

 

[iant]

This Under Inflated talk is now confusing

if you cut any tire or what ever in half and measure the length is not going to alter..

The Height from the Centre of the shaft to the ground will change if the tire is underinflated.
If the rotary encoder calculations are based on the measurement of the diameter when the wheel is touching or on the ground then all the circumferance issues become true.
BUT
If the calculation is done with 'NO LOAD' on the tire then there can be NO variation on the actual circumferance.

Accuracey of rotary encoders will be going to be correct, with the exception of slippage or Homing errors.

I think (not Sure) the antilock braking will be checking every wheel independantly, so 4 rotary encoders, not one.

I have worked in the car industry (press Plant) for many years, encoders or even Chopped Disks are used to a counter. The homing and reset is the major problem.

In Fairness we used steel wheels.