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Rupewrecht
11-07-2007, 11:17 AM
here's an idle thought...

For any BA without ABS, you could retrofit the ABS sensors to the front hubs, right?

Would there be some way of triggering it the ABS sensors themselves to work as a traction control system by means of some aftermarket computer trickery?

As in effect, isn't that what traction control basically is? It just brakes that particular wheel until it stops slipping.

I imagine that making an ECU detect wheel slip would be the hard part though. Something to do with load removed from wheel (as it'd be spinning) and the combination of throttle position.

Thoughts?

DavoAust
11-07-2007, 12:03 PM
would you be able to compare wheel speeds?

after all if one wheel is sllipping it would be going faster than the other right.

you could then work out what sort of revolutions the wheel should be doing without slip if it is getting traction and if it breaks from a say 15% margin then its slipping?

however the differing wheel speeds through corners would also trigger this (assuming you dont have an LSD) hence the 15% margin (may need to be greater, this is only an example)

Rupewrecht
11-07-2007, 12:17 PM
Aha, that's a good idea! Apparently that's how the some aftermarket ECUs do it - by picking up that the car is revving quicker than it should.

DavoAust
11-07-2007, 12:37 PM
it would be interesting to see if it can be done.

you'd need an aftermarket ecu for it wouldnt you? and the wheel sensors and a lot of extra time. if you ever get interested i'm good with maths and can probably work out what of equations you'd need to calculate if the wheel/s were slipping.

Rupewrecht
11-07-2007, 12:51 PM
I've got the Aftermarket ECU (Wolf 3D) and some V6 hubs with ABS sensors lying around.

I'll talk to the monkeys that tuned the Wolf last time and see what they say. The Wolf has auxiliary inputs for extra stuff, but it's a matter of being able to get it to interface the ABS sensors (and then programming the Wolf to understand when they're detecting slippage).

I know some of the current Motec and Autronic ECUs will do TC, but i cbf upgrading ECUs just to get this happening!

I'll do a little investigation and report back :)

Dogo
11-07-2007, 01:10 PM
what would apply the brakes ? some kind of electronic piston perhaps ?

Rupewrecht
11-07-2007, 01:17 PM
Oh that's a good point. the ABS releases the brake application doesn't it? Duh.

Hmm...well, there goes that idea, maybe.

But if the ABS can release the brake, then....ah i dunno.

Aaron
11-07-2007, 02:25 PM
Rupe, tell you what I'll give you my 4-stud ABS ring equipped hubs (as I suspect the ABS rings are NOT removeable). I may have spre apir of sensors too, although you may still have those bolted to your knuckles.

The "trick" would be to also use a pair on the rear, and then do a simple PIC program that provides a YES/NO (ON/OFF) output to the Wolf. You then simply make the Wolf retard the timing/fuel to make the power drop off. The little box/PIC setup woudl simply look at the frequency coming off each front wheel and compare it to the average frequency from the rears. The threshold point for slip would be about 20% difference I'm thinking after you allow for the speed differences between wheels when turning on full lock.

On of the old skool handling/drag texts will probably give the exact slip rate that gives best acceleration vs loos of traction.

The electronics is dead simple if you're handy with the PIC stuff...

A.

Rupewrecht
11-07-2007, 02:51 PM
I've been giving it more thought...but the trouble with retarding stuff is that it slows both wheels. And i can do that with my right foot.

I think to individually slow each spinning wheel (which was the aim), i'd have to install the ABS system (with hydraulic lines and different booster etc) to be able for the system to be able to brake the wheels (from what i've read about ABS systems).

Meh, i think i'll just put my LSD in...and get some new engine mounts to stop the axle tramp :rolleyes: :D


edit: Cheers for the offer of the sensors, i just might end up doing it as well once the LSD is in, as it'd still be useful for when i hit the 'ludicrous speed' pedal. Now i just need to work out what the hell a PIC program is!

project.r.racing
11-07-2007, 03:01 PM
yes it can be done, my kc laser had traction control.

you are on the right track, but it would'nt be applying the brake, but limiting power the same way and rev limiter works.

it is easier with a non lsd gearbox, why? cos when the wheels loose traction, it puts all the power into the left hand side wheel.

hence when you in sensors to each wheel/hub, when the on/off thingo aaron spoke about engages, it's noticing a major difference rotation between the both, then sends a signal to the ecu to cut either the ignition or fuel delivery.

from what i remember, when engaged, the fuel was cut but 20%, causing less power, which helped with taction issues.

on a car with an lsd, the varibles would be much tighter.

ryan

jordy
11-07-2007, 03:13 PM
I think only on newer cars the traction control actually applies the brakes. Hence Aaron could be onto something.

Might not be very effective though, once you've lost traction you'd need a fair bit of power drop to actually regain it. I find if I lose it in 1st in the wet, if I take my foot off then try and put it back on smoothy I usually end up spinning again.

Rupewrecht
11-07-2007, 03:20 PM
Might not be very effective though, once you've lost traction you'd need a fair bit of power drop to actually regain it. I find if I lose it in 1st in the wet, if I take my foot off then try and put it back on smoothy I usually end up spinning again.

Yeah, that was my main problem with the retarding issue.

I think with the LSD in that keeps the same power to both wheels (more or less), then if they both break traction, having the retard thing happening (say up to 20% of the power being applied so it doesn't cut all my power) would be beneficial, i think. At least retarding it by only that much is going to eventually give me back traction, rather than stopping me dead until traction is regained.

Better than a boost controller to limit boost in each gear...just a lot more dicking around :rolleyes:

bourbon
11-07-2007, 03:27 PM
yay for the XR6T had the traction control light on for 10secs while taking off next to a RX7 that wanted to race and he didnt spin any wheels :p hahahahaha

Aaron
11-07-2007, 03:39 PM
You need to look into how the XR6T controls traction. It doesn't apply the brakes, but rather employs torque limiting (which the Wolf probably can't do) through a combo of retard, throttle control (drive-by-wire) and staged spark cuts.

However becuase you have boost controller, you could say bleed of a couple of PSI, back a few degrees out and "voila". You could for example have your tuner find a boost/retard level for say 60% peak power and have those as your targets when in a T/C situation. You'd still be able to break traction but the severity would be reduced, plus you'd more that likely always remain just below the total traction loss point due tot eh speed of the system (see below)

What this does is reduce the power level, without killing it completely off. In the wet it was very possible to have the T/C come on from a standing start and have the car stuttering for 100m up the road sideways before it would finally grip. It's all a matter of tweaking, because the whole thing is computer (PIC is like a computer that does basic computation quickly and cheaply on one chip) controlled it should reduce power output before you get to leaving blackies down the road. If you go LSD then this will become even more useful. The key point is that the computer would be assessing the traction level a lot more times per second with a much higher response time than the drivers body/brain.

Remember T/C and driver aids in F1? Those dudes can drive way better than us, and the computer assists still make them faster!

If you are considering tracking the car you do not want a T/C system that uses brakes trust me on that ;) T/C that activates brakes woudl need a very specialised conversion as a stock Astina ABS unit can only pulse pressure that's in the lines, not raise pressure to a line. I suppose you could achieve this by added a mechanical applicator for the brakes, then hacking the ABS management such that it releases non-spinning wheels and cycles the spinner. Would be hard work though....

A.

DavoAust
11-07-2007, 04:02 PM
wow aaron, where did you learn all this?

hmm, rup if the wolf has a simple on/off input you could have the PIC do all the work and simply send a yes/no single to the wolf where yes is engage traction control and no is normal.. oh, even better, hook a switch up between PIC and the wolf to turn TC on or off

wouldnt be hard to program a PIC to do it either.. but as aaron said you would need the extra abs sensors for the rear.

this style of engine limiting traction control would be more benefical with an LSD. am i right in thinking if one wheel begins to slip with LSD its likely both will as they cant slip independantly like a non-lsd car. so limiting the power and slowing both wheels would work better for a LSD car, as compared to normal where one wheel maybe gripping fine whilst the other is slipping and the power loss will need to be greater to allow the slipping wheel to regain traction.

jordy
11-07-2007, 04:19 PM
It really is the wrong sort of traction control though - it's not distributing drive evenly as well as limiting output, only reducing power to the single wheel that's spinning. It's gonna help, but it certainly wont be ideal.

You should definately install an LSD, and perhaps base the traction loss on front vs. rear wheel speed, then it's as good as any.

Cosmo Dude
11-07-2007, 05:25 PM
The Motecs use the wheel sensors for launch control and telemetry. To do a traction control I would monitor both wheels and diff speeds, it may be easier to upgrade an ABS to include traction control but that may require some connection to the ECU or throttle.

project.r.racing
12-07-2007, 08:28 AM
The Motecs use the wheel sensors for launch control and telemetry. To do a traction control I would monitor both wheels and diff speeds, it may be easier to upgrade an ABS to include traction control but that may require some connection to the ECU or throttle.agreed, check earlier posts.

oh and a question dan, what will you be using thistraction control for, rain? 1/4 mile? track?

Rupewrecht
12-07-2007, 08:31 AM
Oh, it was just a random thought, as i was single-spinning up the road a few night ago in the wet.

Nothing will probably ever come of this, but i was interested to see how it would be done.

project.r.racing
12-07-2007, 10:35 AM
Well your LSD and wider tyres should fix that problem, or some what reduce it.

My LSD goes in next week.

Ryan

Bear
12-07-2007, 05:08 PM
Aaron has the right ideas ... pretty much everything i was thinking as I was reading the thread ... something to do with being a similar sort of warped individual ...

I also remember reading of a Pug 205 built by a couple of guys who worked for Williams ... they built it for hillclimbing and they built their own traction control system (this was nearly 15 years ago ... traction control was just feeding into F1) ... I'm not sure how they ran the sensors, but the did use timing retardation and cutting sparks ... the idea being that you're trying to modulate the power at CPU speeds and keep the tyres on the very limit of their traction ... some drivers can manage this on their own ... most can't

RedLineResident
12-07-2007, 07:39 PM
Now Im pretty sure that ive got LSD in mine, is that standard in a V6 model. What gives me the idea is that ive tested it in my street and got 2 15m long black marks. The marks start together, end together. Also the car gets a fair bit of torque steer when taking off with a light left foot or going into second happily when wet.Ive been very clutch happy lately and the tires are even as can be. So am I right to assume that I have LSD.

Cosmo Dude
12-07-2007, 07:57 PM
LSD was an option only in Japan. A previous owner could have swaped out the trans due to some failure and lucked on to one.
Lucky you.

twilightprotege
12-07-2007, 10:28 PM
biggest problem is going to be working out, especially on a self designed system, is at what acceleration does is the wheel considered to be losing traction?

what many people think about abs is that it releases the brakes when the wheel has locked. this is totally untrue. it releases the brakes when the wheel starts to lock. there is an inbuild pre-determined figure into the computer of the abs, the maximum allowable rate of decelaration. basically they get the car onto an uber sticky road with uber sticky rubber and hit the brakes. lets say the the wheels start to lock up at -40m/s/s decelaration. that's the figured used for abs. so when you're on a wet road and you hit the brakes. as soon as the tyres are decelarating faster than -40m/s/s the abs is released until it's below that figure and therefore the wheels dont lock up.

probably doesnt help you in any way shape or form, but it'll be hard to work out.

rodhog
13-07-2007, 12:19 AM
well here is what I remember.

I know of a few guys using - Motec systems and anti-lag.

Along that comes traction control. Most traction control operates on the wheels sensors determining that wheels are going faster then others now.

before we go into this and that.
Let me take along the 4WS systems - they have a direct feed of speed fomr a gearbox to determine when to change from one phase to another or to turn on in the case of Hicas systems in nissans.

ABS sensors most are on all 4 wheels, now if you have enoguh pwoer you find on ABs cars - like my Mx-6 that. it will shut down when one or two sets of wheels are going totally differrent to the other regardless of ABS.
Now here in lies the catch my 4WS shuts down when wheels go bananas ion speed as well. why you may ask because it uses the rear wheels speed in comparisson to the front wheels to compare and vary angle - see 4WS uses it's own direct gearbox speed sensor along with the main virchle speed sensor in the speedo.

What's this got to do with traciton control.

Okay taction control does not see each wheel- Not untill now these top range unit do they. You will also note Most LSD equiped or evne perofrmance cars don't use the brakes as the traciton device. They let ESC or similar individual brake wheels for body control.
Traction is controlled - how it should be by the throttle.
alot of you should know by now it's one reason for electronic throttle body's. A good example is 2JZ's twin setup one for human one for TTC- toyota traction control. Another good one is Opel ( holden) vectra 2.5/2.6L v6 has twin controlls in it again but both electronic stepper motors.

The type you seem ot favour - of abs controlled - you have to go back. Bakc ot when ABS pumps were hmm - bigger.
ABs pumps from eighties onward went from 50KG units ( I got one on my floor don't try and pick it up keeps the lid on the monsters down stair) to current bosch units of about 5Kg's or less. New audi types for total brake control are not heavy but bigger and control more. They do pump the brakes control pressure and control the brakes. AS noted by R&D people don't hit brakes hard enoguh often so they now do it for use in emergency. they od it with correct sized pistons etc.
How to make this traction control, well you need ot A have ABS = B have alot of money. that's if you wanti t like factory.

the type I've always seen useing the abs just applies the brakes on each individual wheel.

Wolf - will not be enough.

you need to the PLC to know what wheel speed is across all 4 it comapres it then apllies force to the wheel with east traction spinning most. it needs to get it to a tolerable value. Now in 2WD yes you only need to control the two brake calipers. But here is the other problem - Some brake calipers don't take it well. Especially alloy types. One problem mazda had with the GD ABS was it would over time bend the calipers due to the force. If abs is used excessivly yanks worked it out first.

Now there is an advantage in this typw you cna eep the engine revs in the torque zone until you get to traction which is great in staying on boost.

one thing to note is older car abs is alot courser - - alot better on gravel then mid 90's super quick.

the other thing is you will need rear sensor speed to compare so not just front sensors. why because you need a speed not related to the actual driveline. It's why my ABS and 4WS knows when to shut down. I have 6 speed sensors effectively but in tern two car speed 4 wheel.

IMO traction is in the right foot.

Aaron
13-07-2007, 10:26 AM
I think we've already killed the ABS derived solution ;)

My idea of using a some embed device (PIC seems most logical) to compare 4 wheel speeds, and then trigger a "cut mode" in the Wolf is pretty straight forward, the Wolf can react to a single input, and if the Boost controller has enough smarts it can also do that. The Wolf couldn't do alternate spark cuts but by backing out timing it will drop power.

What people are forgetting is that the "trigger" occurs before there's true tyre frying traction loss, the electronics reacts quicker than Rupes foot and cuts power while also advising him (via a dash light) to maintain throttle position rather than increase it (or back off). All T/C systems can be overpowered if the driver does not respond because they all have an "allowable" level of measured slip. However becuase we're gettign early discovery we only need to loose say 20hp to drop below the slip threshold - something that is quite easy to do with timing.

As for the threshhold point where slip is exccessive, it's pretty well documented by the drag fraternity, and for the most part is considered to be 10-30% range with the commonest rule of thumb being 20% and most off-the-shelf systems will be adjustable between 20-50% slip. So there's no black art there.

In all honesty this implementation of this at a crude level is dead easy - ABS sensors feeding into the T/C controller will tell us wheel speeds. The Wolf can be configured to do "something" basic when given a switched input and Dan can be trained to respond to the big light etc. Where the Motec systems come into their own is the complete control of power or rather torque output for a given condition. If the car had ABS then it woudlbe more difficult becuase we'd have to buffer the wheel sensors correctly and likewise if there was another system runing off the same senor arrays.

To do that you need the electronic throttles, dropped spark, AND timing/fueling changes all working together and that costs $$$ in configuration and tuning time.

Naturally we could expand our system to do a few more things.
* 10-30% slip it pulls timing out of the Wolf.
* 30-50% slip it pulls timing from Wolf and forces the Electronic Boost controller to cycle the wastegate to reduce the generation of boost.
* 50% + we cycle the wastegate and the BOV to essentially remove all boost, or force the throttle closed which could be done with an extra (Big) throttle body and a small actuator to close it.

Suddenly we've got a very advanced system using mostly ghetto parts and not need to invest $3000 in a new ECU and wiring. Costf or the system for a well connected dude liek Dan? Maybe $200 in sundry used junk and beer fro the PIC guru.

A.

Rupewrecht
13-07-2007, 10:55 AM
and Dan can be trained to respond to the big light

:p

Damn you make it sound so easy...and tempting. Once the LSD gets put in, i'll see how necessary it is. Wolf make an EBC, as i've just got a bleed valve atm, but that's easy.

And you're dobbing yourself in as the PIC guru ;)

Aaron
13-07-2007, 11:37 AM
:p
And you're dobbing yourself in as the PIC guru ;)


Erm I did mention somewhere earlier that I know about what they can do but I've actually not worked with them... Yet.....

Was actually thinking of picking up a DEV kit and giving it a go in the coming months...

A.