DCCD control

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wrxbart
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Joined: Mon Jun 15, 2009 10:23 pm

DCCD control

Post by wrxbart » Sat Jan 18, 2014 11:29 am

On the S6 what inputs can you use to control the DCCD? TPS, vehicle speed, brake pressure anything else ?

pavlo
Zen Performance
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Re: DCCD control

Post by pavlo » Sat Jan 18, 2014 12:09 pm

you can also use handbrake to turn it off.

wrxbart
Posts: 11
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Re: DCCD control

Post by wrxbart » Sat Jan 18, 2014 1:12 pm

Ok not really needed that one I don't think. Can you log individual wheel speeds? Also how is the traction control function controlled via the S6?

pavlo
Zen Performance
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Re: DCCD control

Post by pavlo » Sat Jan 18, 2014 1:21 pm

The wheel speeds are only used in the DCCD to provide vehicle speed as a single input. It doesn't do slip control but on a proper tarmac/circuit car this is much less of a concern.

Traction on the S6 is done the same as the S8 and it compares vehicle speed with driven speed. Vehicle speed is typically front wheel speed and driven speed is typically the rear wheel speed (either min, average or max for both) which for a full time 4wd is less useful when all 4 wheels start to spin. GPS speed as a input from an external box can be used if you have a nice update rate but currently GPS speed from the GPS module cannot be used (firmware restriction).

You are not going to have enough inputs for a VVT engined car with flatshift and dbw to use 3 wheel speeds (min recommended), it will be tight even with a non dbw car.

pat
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Re: DCCD control

Post by pat » Sun Jan 19, 2014 2:57 pm

Whilst Paul has done a great job answering the question I'll just add the following : At the Autosport show this year one of our dealers told me about a unit which they have made that can accept 4 wheel speed inputs and then outputs them as Bosch M4 Motorsport ABS stream, which the S6 can receive. This could be a lower cost option for someone needing more inputs than an S6 has, where that increased requirement is due to wheel speeds (it isn't as generic as the I/O10). I don't have pricing at present, but I do know it will be considerably less than the I/O10 :)

Cheers,

Pat.

pavlo
Zen Performance
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Re: DCCD control

Post by pavlo » Mon Jan 20, 2014 11:27 am

I was doing to do that, wow, saved me the trouble!

Paul Doyle
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Re: DCCD control

Post by Paul Doyle » Mon Jan 20, 2014 1:29 pm

This is an intresting thread, the availability of a low cost CAN based wheel speed sensor would be a welcome upgrade for the S6 and will make the unit even more attractive than it is currently.

Are there any plans to implement DCCD wheel speed slip control during the forthcoming season? I would welcome its addition, and I'm sure its inclusion would make the S6 package more appealing to many of the rally teams out there who, like me, currently use GEMs/Motec dedicated DCCD controllers (as they both offer slip control).

Off topic a little but also of intrest is the GPS speed sensor, what hardware (if any) is currently available that could feed a reliable GPS speed signal to the ECU such that true 4wd traction control can be achieved. I would think a refresh rate of 10hz minimum would be required (20hz probably better). If such hardware is available how does it deal with loss of GPS signal?

Some of the other new products/gadgets displayed on the Life racing stand also at the Autosport show caught my eye.....hopefully these too will be made available by the Syvecs team in the not to distant future.

pavlo
Zen Performance
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Re: DCCD control

Post by pavlo » Mon Jan 20, 2014 3:35 pm

do you need slip control on a circuit car? I don't think you do.

Paul Doyle
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Re: DCCD control

Post by Paul Doyle » Tue Jan 21, 2014 11:41 am

Do I need DCCD slip control on a circuit car?.....probably not

But maybe a better question would be: Does DCCD slip control improve lap times on a circuit car? I believe it does.

Let's consider a real world example, Clearways and Clarke Curve at Brands Hatch

At corner entry and toward the first apex of the complex most cars (at least 4wd cars that compete in Time Attack) will exhibit understeer characteristics, As the first apex (Clearways) is reached throttle is progressively applied and the car will change and tend toward oversteer. How much oversteer? And more importantly will it be balanced? The ideal being a 4wheel power slide if and when the limit of traction is reached. The answer to the "will it be balanced?" question depends on lots of things such as chassis, diffs and aero setup (and probably lots more). But the balance is also affected by other factors that are (in some cases partly) outside of the drivers control, such as; the camber of the track, the temperature and condition of the tyres, whether the track is wet or dry, fluid on the track etc etc….

In my car (fitted with DCCD slip control) when I drive out of Clearways at full chat toward Clarke I can feel the car start to exhibit oversteer (i.e. back end starts to drift out)…..I keep my foot in and I can sense that the DCCD controller detects that oversteer through the wheel speeds and it applies lock to the centre diff, this all happens in the blink of an eye, the result being the backend no longer wants to step out and I can keep the throttle pinned as apposed to letting off a little (or applying opposite lock if I have any track left)….

Can you achieve this type of control/balance in all conditions at every corner on any track with the current (Syvecs DCCD) strategy? I don’t think so, but at the same time I've not done extensive testing so I can't say its impossible.

I would suggest DCCD slip control can be set-up to deliver closed loop oversteer correction on corner exit when getting on the power and I know, through experience, it does work well on circuit cars. And on gravel rally cars it is (in my opinion at least) an absolute must.

Andrearally
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Re: DCCD control

Post by Andrearally » Mon Mar 03, 2014 9:56 pm

Yes we developed a small unit with 4 wheel speed input and CAN with BOSCH M4 protocol output.
Next week we will start track testing, but on the bench is working ok.

About slip control on DCCD or ACD, I can tell you my experience on rallying, on tarmac I can found nearly 0,3-0,5 sec each km, on gravel depends from drivers but often no difference.
Andrea Maselli
www.am-race.com
Personal Blog www.andreamaselli.com

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