Traction Control Addition

Testing and development of Megasquirt 3

Moderators: jsmcortina, muythaibxr

Traction Control Addition

Postby wes kiser » Sat Oct 07, 2017 7:13 pm

It has been a while since I have paid attention here, so forgive me if this has been discussed.

I think it would be useful to add a "rate of rise" traction control scheme for drag applications. The "perfect run" implementation certainly works ok until slip gets bad enough to truly be "behind" but after that point wheel speed is so low relatively to the timing curve it is effectively "all over." The true physical thing we are controlling is at any given wheel speed there is a maximum "rate of rise," and above that it is slip.

This would obviously require a new calculated parameter for wheel speed rate of change. Then also a calculated "% slip vs. rate of change." The user would need to input max allowable rate of change vs. wheel speed. For simplicity purposes %slip could simply be calculated as "rate of change/allowable rate of change." This could then easily be fed into existing perfect run traction control reactions. I am sure the curve would look slightly different, but the same reactions could be used.

In general, at slip onset their is a relatively large change in rate of change. Advantages to doing this in this manner in addition to what is discussed above is you completely remove the dependence on the launch timer.
86 Rx-7, swapped to 2.3 ford turbo (BW EFR 6758), ms3/ms3x sequential fuel /waste spark, ls2 coils
88 Tbird 2.3t, Microsquirt Module (PIMP), TFI ignition
wes kiser
Super MS/Extra'er
 
Posts: 1318
Joined: Tue Jan 03, 2006 2:49 pm
Location: Charlotte, NC

Re: Traction Control Addition

Postby jeffmarsh750 » Sat Oct 07, 2017 11:00 pm

Yes I agree. It would be a simple traction control but very effective. Make it self learning and make big $
jeffmarsh750
Experienced MS/Extra'er
 
Posts: 266
Joined: Fri Nov 23, 2012 3:17 pm

Re: Traction Control Addition

Postby samh » Sun Oct 08, 2017 3:43 pm

I agree Wes
samh
Helpful MS/Extra'er
 
Posts: 60
Joined: Mon Nov 07, 2011 5:27 am

Re: Traction Control Addition

Postby Matt Cramer » Tue Oct 10, 2017 7:08 am

I like this idea as well. A maximum rate of acceleration vs speed could work in quite a few situations, including (at least theoretically) an all wheel drive rally car where it could possibly spin all four tires and a launch timer would not be applicable.
Matt Cramer
Super MS/Extra'er
 
Posts: 13646
Joined: Thu Apr 16, 2009 8:08 pm

Re: Traction Control Addition

Postby cj.surr » Thu Oct 12, 2017 5:07 am

I think this could definitely be a better way around traction control for cars without speed sensors on undriven wheels.
cj.surr
Helpful MS/Extra'er
 
Posts: 39
Joined: Fri Jul 29, 2016 4:28 am

Re: Traction Control Addition

Postby jsmcortina » Thu Oct 12, 2017 5:29 am

There's a technical challenge to this. Very frequently you can blow the tyres away on an initial launch. Measuring the VSS and rate of change of VSS from rest is the most difficult time. If you aren't able to achieve this fast enough, you can be spinning away at a near constant VSS. i.e. getting the balance right between smoothing and response time is not easy.

James
I can supply, repair or upgrade Megasquirts in UK. http://www.jamesmurrayengineering.co.uk

My Success story: viewtopic.php?f=104&t=34277
MSEXTRA documentation at: http://www.msextra.com/doc/index.html
jsmcortina
Site Admin
 
Posts: 33911
Joined: Mon May 03, 2004 1:34 am
Location: Birmingham, UK

Re: Traction Control Addition

Postby whittlebeast » Thu Oct 12, 2017 9:09 am

We thought about this years ago. I wanted to use the gear ratio in the calc and watch the teeth of the crank rate of change (RPMdot) to get the resolution you need to to effectively do traction control. The problem get into this when you account for automatic transmissions.

Andy
User avatar
whittlebeast
Super MS/Extra'er
 
Posts: 2132
Joined: Tue May 04, 2004 8:20 pm
Location: St Louis

Re: Traction Control Addition

Postby wes kiser » Thu Oct 12, 2017 9:10 am

That is certainly true to a point James, but functionally the same "issue" applies in the current strategy. I think applying instantly from zero speed likely is a loosing proposition anyway when dealing with a "driven" only scheme. I think the only way this works is to begin performing the calculation "speedot" from zero, but don't start applying corrections until you exceed the "minimum speed for VSS" number.

When I am looking at a wheelspeed graph, their is almost always a drastic increase in wheelspeed when spin is present, and it is very easy to spot. I am quite confident this would be a useful traction control addition, particularly for radial tire automatic drag cars. I can provide you with logs of spin vs. no spin for a typical car, it makes this quite obvious. There almost always is some necessary slip "on the hit" even on a good run, but the wheels don't "come off" until 10-15mph generally. At that point on a bad track wheelspeed may increase at 80 mph/s instead of say 35mph/s for a good run. If you would like to give it a shot, I also have a customer car currently in testing that would be available to provide feedback (at least until racing season is over in the southeast US).

I do concede I am fairly ignorant as to how quickly this calculation can be updated and applied to a correction within the ecu. I do know the existing systems that do it certainly talk up how quickly they perform the calculation/corrections.

I certainly understand every one thinks "their' proposed updates/strategies are "must haves" and you can't spend time on every one. I can think of no "con" compared to the current perfect run, and if it did nothing but remove the dependency on the launch timer this alone would be beneficial (then you don't have to account for transbrake release delay, which in and of itself varies slightly).
86 Rx-7, swapped to 2.3 ford turbo (BW EFR 6758), ms3/ms3x sequential fuel /waste spark, ls2 coils
88 Tbird 2.3t, Microsquirt Module (PIMP), TFI ignition
wes kiser
Super MS/Extra'er
 
Posts: 1318
Joined: Tue Jan 03, 2006 2:49 pm
Location: Charlotte, NC

Re: Traction Control Addition

Postby NiceMan » Thu Oct 12, 2017 9:50 am

There has any mind why traction control spark retard is max 30 ? Can it make to like 40 ?
Motor still make too much power =) Not want use Spark Cut because make noise, some place too much..
Boost duty is too slow ..
Last edited by NiceMan on Tue Oct 24, 2017 7:47 am, edited 1 time in total.
http://www.theniceman.com/
Ford Taunus Coupe 1975 2.0i Turbo
Ms3 + MS3x
NiceMan
Helpful MS/Extra'er
 
Posts: 107
Joined: Fri Mar 25, 2011 11:51 am
Location: Finland

Re: Traction Control Addition

Postby jsmcortina » Thu Oct 12, 2017 10:02 am

wes kiser wrote: I can provide you with logs of spin vs. no spin for a typical car, it makes this quite obvious.

If it is 'obvious' in a datalog, then there's a good chance that the data can be used.

James
I can supply, repair or upgrade Megasquirts in UK. http://www.jamesmurrayengineering.co.uk

My Success story: viewtopic.php?f=104&t=34277
MSEXTRA documentation at: http://www.msextra.com/doc/index.html
jsmcortina
Site Admin
 
Posts: 33911
Joined: Mon May 03, 2004 1:34 am
Location: Birmingham, UK

Re: Traction Control Addition

Postby 93supercoupe » Tue Oct 24, 2017 7:35 am

Rather then wheel speed, could accelerometer input be used?

Ive been thinking about something like that for a while. Something that adds or subtracts power based off accelerometer feed back. Havent been able to fully wrap my head around so i havent made a thread.
1988 BMW 325, m52, s52 cams, HX35/HX40 hybrid, MS3x, 537whp/509wtq on 22PSI, pump gas, stock engine
1998 BMW M3 Sedan, Lq4 6.0, twin ebay 66's, Ms3 Gold box, 770whp/750wtq 19psi
1998 BMW 328i Sedan, forged lq4, twin Borg s366's, built th400, MS3 Ultimate, 9.2 at 150 on 22psi
93supercoupe
Experienced MS/Extra'er
 
Posts: 368
Joined: Sat May 10, 2014 4:57 am
Location: Haddam, Ct, USA

Re: Traction Control Addition

Postby Laminar » Tue Oct 24, 2017 3:00 pm

93supercoupe wrote:Rather then wheel speed, could accelerometer input be used?

Ive been thinking about something like that for a while. Something that adds or subtracts power based off accelerometer feed back. Havent been able to fully wrap my head around so i havent made a thread.


In a straight line, an accelerometer wouldn't be able to tell the difference between part throttle and wheelspin.

You could maybe use an accelerometer to maintain a specific drift angle.
Laminar
Experienced MS/Extra'er
 
Posts: 287
Joined: Wed Aug 06, 2014 7:45 am

Re: Traction Control Addition

Postby jeffmarsh750 » Sat Nov 25, 2017 10:22 am

Base it against time after launch. And fix the timers so they actually match real time.
jeffmarsh750
Experienced MS/Extra'er
 
Posts: 266
Joined: Fri Nov 23, 2012 3:17 pm

Re: Traction Control Addition

Postby wes kiser » Tue Nov 28, 2017 8:45 am

jeffmarsh750 wrote:Base it against time after launch. And fix the timers so they actually match real time.


The existing method is already explicitly tied to time after launch, as is already an entire host of "from launch timers" (boost, timing, nitrous, fuel, etc....). The advantage of what I am suggesting, is linking it to allowable acceleration vs. wheel speed completely removes the time from launch dependency, and is the basis of how the current better standalone TC systems handle driven wheel speed only traction control. The problem with linking anything about traction control to launch, is by definition if the run gets slowed down at any point (excessive wheel spin, pedaling it, random issue) it can no longer work at all.
86 Rx-7, swapped to 2.3 ford turbo (BW EFR 6758), ms3/ms3x sequential fuel /waste spark, ls2 coils
88 Tbird 2.3t, Microsquirt Module (PIMP), TFI ignition
wes kiser
Super MS/Extra'er
 
Posts: 1318
Joined: Tue Jan 03, 2006 2:49 pm
Location: Charlotte, NC


Return to MS3 Development

Who is online

Users browsing this forum: No registered users and 1 guest