Traction control with 4 wheel speed inputs?

[Reverant]

Hi,

I have a car that doesn't have a gearbox sensor, only ABS sensors on each wheel. I have connected them successfully to the MS3 and getting proper wheel speeds, but now I want to enable traction control.

The current code assumes that VSS1 is the driven wheel and VSS2 is the undriven wheel.

The problem is my case is that VSS1 is one of the TWO driven wheels, so it may not be the spinning wheel (ie maybe its the outer wheel in a tight turn, and only the inner wheel is spinning).

So, when enabling 4 wheel speed sensors, it should be so that VSS1 and VSS2 are the driven left and right wheels, and VSS3 and VSS4 are the undriven left and right wheels.

Then, VSS1 and VSS2 are compared against VSS3 and VSS4.

Like this:

if ((vss1 > vss3) || (vss2 > vss4))
do_traction();

Thoughts?

[jsmcortina]

Or might it be better to use the average of VSS1 and VSS3 vs. the average of VSS2 and VSS4 or something similar? Or compare all wheels? Ideas welcome.

James

[nathaninwa]

A friend of mine with an LS powered sand rail with a Pro has talked about wanting to average each rear wheel speed for boost by gear capability. These cars use rear turning brakes so using a single sensor just won't work. We understand that calcs won't be exact during those sitatiions but sure will get us closer

[mazdaspeed]

I am going through the same as you i hooked up all the wheels and it will only detect slip on vss1 so now ive ordered a inline speedo cable adapter/tranducer for vss1and will have to rewire my speed inputs. I guess I assumed that if they have the option for 4 vss's the code would use it for traction control also


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[mazdaspeed]

If either vss1 or 3 read higher than vss2 or 4 traction control activates would be mint

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[Reverant]

Or might it be better to use the average of VSS1 and VSS3 vs. the average of VSS2 and VSS4 or something similar? Or compare all wheels? Ideas welcome.

James

What I recommended above will work in both straight line acceleration as well during turning.

I don't see how averaging will help in this case.

[thokes82]

On the non driven axle it should be the faster wheel to compare too. This is to prevent issues when you have a locked up inner wheel while breaking into corners.

[tpsretard2]

Traction control and active diff control are calculated very similarly.

The should both be mapped based off the slip angle.
Slip is the difference between average front wheel RPM and Average rear wheel RPM (Fastest - Slowest). Doing it this way makes it easy to map vs having a bunch of tables and modifiers.

This allows you to have a small (or large) 3d map. This is not much of an advantage for a staging/launch traction, how ever when actually driving around, like going around a corner or changing surface under hard accell. It is amazing being able to control it on a 3d map.

Jason

[thokes82]

Averaging the non-driven wheels is bullshit. You need to compare to the faster one. And what shall the 3D Map be for? Describe what you want the x and y to represent and what is the response (z-axis)?

[tpsretard2]

as it is bullshit i will graciously bow out here.

[nathaninwa]

as it is bullshit i will graciously bow out here.

Don't take one repsonce and quit. It's brain storming ideas like this that may help develop or inspire more ideas and get coding into place

[motthomas]

as it is bullshit i will graciously bow out here.

Don't take one repsonce and quit. It's brain storming ideas like this that may help develop or inspire more ideas and get coding into place

I think he may be referring to the aggressive nature of the reply rather than the fact it was suggested his ideas will not work. I for one felt the reply was unnecessary and did not contribute to the discussion.

[jsmcortina]

Perhaps it was a language or culture difference, but it sounded harsh to me too.

I'm interested to hear different strategies and their perceived advantages.

James

[aidandj]

Does anyone know if there are any good OEM white papers out there on traction control.

Or how the race logic box does it?

[Reverant]

There are no good white papers on TC my friend. (sorry, I just had to use the movie reference).

Since (probably) no one here is a traction control expert, I would suggest adding a few options to suit with everyone's idea of how it should be done. Ie compare average of front to rear axle, compare front left with rear left and front right with rear right, compare highest of driven wheels to lowest of non-driven wheels, compare each wheel to GPS VSS (for 4wd cars) etc. Just like we have different algorithms for fuel control and for acceleration enrichment I guess.

These 4 options would be a nice start. Then we can compare datalog results.

James?

[MS2tester]

maybe add compare un-driven wheel versus un-driven wheel
if difference gets higher than specified number traction control is disengaged
thinking off high speed corners where an un-driven wheel is lift off the ground

[whittlebeast]

There are no good white papers on TC my friend. (sorry, I just had to use the movie reference).

Since (probably) no one here is a traction control expert, I would suggest adding a few options to suit with everyone's idea of how it should be done. Ie compare average of front to rear axle, compare front left with rear left and front right with rear right, compare highest of driven wheels to lowest of non-driven wheels, compare each wheel to GPS VSS (for 4wd cars) etc. Just like we have different algorithms for fuel control and for acceleration enrichment I guess.

These 4 options would be a nice start. Then we can compare datalog results.

James?

see http://www.racelogic.co.uk/_downloads/t ... Manual.pdf

Andy

[MS2tester]

hondata system maybe for some idea,s?
https://www.hondata.com/traction-control-help

[jsmcortina]

On the non driven axle it should be the faster wheel to compare too. This is to prevent issues when you have a locked up inner wheel while breaking into corners.

But are you braking into a corner while also trying to accelerate and spin the wheels?

The traction code is only designed to work when you are on the throttle accelerating.

James

[jsmcortina]

I've implemented some new options for the next pre-1.5 alpha code.

James