BNR34 AWD traction control (atesa + ABS sensors), who has done it ?

[Dose Pipe Sutututu]

On 25/03/2022 at 12:21 PM, bcozican said:

assuming not by the details in the discussion bit does Haltech upgraded software allow traction control through DBW?

Sure can  

Here's another mock up I've done for you (you can add more dimensions to it, such as a rotary trim switch position OR canbus keypad selection)

Note I do not work for Haltech, I just like their products as it's affordable and user friendly for the enthusiast tuner such as myself.

[bigboss59400]

Thanks a lot for your answers!

So basically it will be for a setup around 800bhp, street use and some track days.

It's not meant for racing so I don't think I will have a lot of traction control scenarios as I want to keep it as simple as possible. Less effort for max performance.

So basically if the aftermarket ECU can deal with the quite high speed ABS wheel sensors (and maybe some circuitry in between to feed ECU with square wave) then it's just a matter of creating/tuning a map. This doesn't look too complicated or am I missing something ?

Then finally I'm considering keeping the ATTESA system as it's taking into account much more parameter that I thought.

I'm just concerned on how these 2 systems would work together :
exemple, low friction on straight line full power, the rear wheels start to spin then the ATTESA will send some power to the front until the rear stop.
But the aftermarket control see it too so it will reduce power ? or should it reduce power only when the front spin ? or should the aftermarket trigger only when the attesa system can't manage anymore: ie when the rear/front wheels are still spinning when the F/R torque ratio is 50/50 ?

/cdn-cgi/image/format=auto,onerror=redirect,width=1920,height=1920,fit=scale-down/https://www.gtr.co.uk/attachments/1648330759137-png.272474/ It looks like there is a front torque meter, can someone point me out what is it and where it's located ?Also is 30kg.m maximum measurable value ?

Thanks again for your advice

[joshuaho96]

On 3/26/2022 at 3:27 PM, bigboss59400 said:

Thanks a lot for your answers!

So basically it will be for a setup around 800bhp, street use and some track days.

It's not meant for racing so I don't think I will have a lot of traction control scenarios as I want to keep it as simple as possible. Less effort for max performance.

So basically if the aftermarket ECU can deal with the quite high speed ABS wheel sensors (and maybe some circuitry in between to feed ECU with square wave) then it's just a matter of creating/tuning a map. This doesn't look too complicated or am I missing something ?

Then finally I'm considering keeping the ATTESA system as it's taking into account much more parameter that I thought.

I'm just concerned on how these 2 systems would work together :
exemple, low friction on straight line full power, the rear wheels start to spin then the ATTESA will send some power to the front until the rear stop.
But the aftermarket control see it too so it will reduce power ? or should it reduce power only when the front spin ? or should the aftermarket trigger only when the attesa system can't manage anymore: ie when the rear/front wheels are still spinning when the F/R torque ratio is 50/50 ?

/cdn-cgi/image/format=auto,onerror=redirect,width=1920,height=1920,fit=scale-down/https://www.gtr.co.uk/attachments/1648330759137-png.272474/ It looks like there is a front torque meter, can someone point me out what is it and where it's located ?Also is 30kg.m maximum measurable value ?

Thanks again for your advice

It's not too complicated but you will need to test it in the real world with ECU logs to refine it. As you have correctly identified you have to be careful about how you implement your strategy because reducing throttle input can cause the ATTESA system to reduce transfer case pressure, which is probably the opposite of what you want to happen when the car is losing traction. Also, if you're going to be building this thing to output 800 hp consider the impact of both soft fuel cut and ignition timing retard on the engine. Soft fuel cut will need some work to make sure AFRs don't go too wonky and some work to make sure the harmonics generated by running only 4 or 5 cylinders doesn't cause problems, ignition timing retard make cause EGTs to skyrocket past safe levels. The "front torque meter" in an R34 GTR is in the MFD. It is a number that exists, but is not particularly useful. It is not measuring anything. It is basically just an internal conversion table that takes the duty cycle target from the main torque split routine and converts it to a "kg-m front torque" value based upon whatever conversion they had from testing a prototype. The actual state of your transfer case clutch pack including the age and order/orientation of the clutch plates, the fluid used, the state of the fluid, the state of the pump's ability to produce pressure, the actual grip of the front tires, the actual torque output by your engine, etc all impacts how much torque actually gets sent to the front wheels especially because the factory front diff is open.

My first thought would be DBW to let the ECU be able to close the throttle and in the ECU output to ATTESA instead of sending it something related to TPS voltage I would instead take accelerator pedal position. Do some experiments to figure out how the factory TPS voltage is related to accelerator pedal position so you can get close to stock behavior at first. Also you should know that the TPS voltage is not sent exactly as-is to the ATTESA controller, instead it's some percentage of the TPS voltage.

[bigboss59400]

Thanks for your detailed answer !

By soft fuel cut you meant lower injector duty cycle ?

My question might be stupid : why not stop the ignition for all cylinders but still opening a bit the injector to not rise the temperature too much ?

I never noticed such front torque caracteristic on the MFD, I will have a look next time

your thought looks very good ! thank you for the strategy !

[joshuaho96]

On 3/29/2022 at 9:53 AM, bigboss59400 said:

Thanks for your detailed answer !

By soft fuel cut you meant lower injector duty cycle ?

My question might be stupid : why not stop the ignition for all cylinders but still opening a bit the injector to not rise the temperature too much ?

I never noticed such front torque caracteristic on the MFD, I will have a look next time

your thought looks very good ! thank you for the strategy !

By soft fuel cut I mean what was discussed before, cutting fuel to cylinders in a random fashion. So maybe every engine cycle (720 crank degrees) you are cutting fuel to one of the six cylinders. Or maybe two of the six cylinders. You cannot reduce injector duty cycle because that will just cause a lean-out that blows up your engine. Stopping ignition to all cylinders while still injecting fuel is a hard ignition cut limiter. Continuing to inject fuel like this without ignition is a very dangerous game to play, the air and fuel will be mixed properly and any spark or sufficient heat will cause it to ignite, possibly in the exhaust which can damage the cylinder head and turbine. As a general rule if you need to hard cut rev limit you should cut all fuel injection to all cylinders. OEMs do this not just for emissions reasons but also because it's a lot safer. Just the air pumping through the engine with no fuel will cool things down. The only danger as I mentioned is if your transient fuel control is not good, then constantly cutting fuel injection and resuming may cause lean-out. DBW is easier for this reason, just force the throttle to close to reduce torque instead.

[bigboss59400]

Just a confirmation, since my front and rear are LSDs

I can connect only one rear and one front wheel speed sensor ?

[Dose Pipe Sutututu]

On 09/04/2022 at 12:48 AM, bigboss59400 said:

Just a confirmation, since my front and rear are LSDs

I can connect only one rear and one front wheel speed sensor ?

Yes you can, however your traction control won't work where you are spinning all 4 wheels.

You need a GPS sensor to make the traction strategy work with a 4WD car work properly.

[bigboss59400]

If the 4 wheels are spinning,

Do you mean the traction control will not work if I connect only 2 over the 4 wheel speed sensor even if I have LSDs ?

Or do you mean I need a GPS to get the actual speed of the vehicule ? If so then yes I thought of adding a sensor like this but thanks for pointing this out again

 

Instead of a GPS which is quite slow, I'm looking in ground speed sensor type (radar at 24Ghz) but there are not a lot of brand and looks like it's not cheap too !

Edited April 8, 2022 by bigboss59400

[Duncan]

If you want good quality traction control you need 4 wheels speed sensors. There is a mile of time (in traction control terms) between one wheel slipping, the slack being taken up, the diff locking, slack to the other wheel taken off and grip being delivered. No modern system is OK with that, single sensor ABS was obsolete about 30 years ago.

Also, I would never use just GPS for traction control. It is way to slow and inaccurate, particularly for rally use with large trees around. If it can be a 5th input to a system I would add it but you almost never have to deal with a situation with all 4 wheels slipping, at the same time, at the same speed unless you are doing it on purpose...