Attesa Sesnor Operating Current

[ebola]

Hi all.

Now, its not too hard to dig up how the attesa computer uses the output from the G-sensors in the middle of the car.

I want to know how many mA the voltage sensors operate at (or the G-sensors output). I want to grab a coupe of resistors and a potentiometer to wire up my own.

80 mA from an 8V source is easy, Its just with my track record, I don't want to guess... can anyone smell ozone?

I know there is an electronic controller (Duncan's) on the forums, and it looks great... Its just not quite what I am after. It does reduction of the lateral sensor only, and I want to be able to put a preload (even if its static) on the longitudinal sensor (eg - constant 10kg front torque split).

not fancy, but fun... its about time I made some modification to my car.

[mazgtr]

This is an old Autospeed article, hope it helps...

Cheers Matt...

The Japanese manufacturers Blitz, Field and HKS produce torque split controllers for the GT-R. I managed to source a Japanese magazine review of one of the controllers and get the article translated. The translation showed that the device plugged into the centrally-mounted G-sensor and that it certainly altered the handling characteristics! I figured that it must change the output of the G-sensor, perhaps increasing it so that the four wheel drive ECU thought that the car was cornering harder than it really was. Wouldn't this direct more torque to the front wheels?

Armed with a multimeter and an assistant, I measured the output of the G-sensor in all sorts of driving conditions. I soon found that there isn't just one G-sensor - there are three! Two measure longitudinal acceleration (ie acceleration and braking) and the other measures lateral acceleration (ie cornering). All three sensors have a 0-5 volt output signal. When there is no acceleration, the sensors all have about 2.5 volts output. The harder the car is accelerating, the higher the voltage output from the longitudinal G-sensors. When decelerating, the sensor voltage drops to below 2.5. With the lateral G-sensor, the voltage decreases below 2.5 on right turns and increases above 2.5 volts on left turns.

My electronics skills are near to zero so I called on some experts to design an amplifier. This device would boost the output swings of the lateral accelerometer, while at the same time leaving the 2.5 volts 'stationary' output untouched. The amplifier was designed and fitted to the lateral sensor output, but sadly there was absolutely no difference in the car's behaviour. The standard dash-mounted torque split gauge also behaved as standard. Another amplifier design was developed (this time designed and built by my Father), and it was duly fitted. Weeks of experimentation followed. The amp was working - when it was connected to the longitudinal sensors I could boost straight-line acceleration torque going to the front wheels, but with only limited benefits when cornering. But when it was connected to the lateral accelerometer, little changed. Did the lateral accelerometer even work? I wondered.

Stunning

The first breakthrough came when I took the unlikely step of rotating the G-sensor package through 90°. This meant that the lateral G-sensor became the longitudinal, and the longitudinal became the lateral. Sounds terrible, doesn't it! This was done because I realised that the longitudinal sensors had a very powerful influence on the torque split - something that the lateral sensor didn't appear to have.

Turning the G-sensor package through 90° made a stunning difference to the handling. Instead of being a car where every slow corner exit required a gentle foot and/or opposite lock, now full throttle could be used with near-impunity. For the first time it simply felt like a proper four wheel drive car....... But there proved to be some negatives. Firstly, in tight corners taken with a high entrance speed, the car could now understeer excessively. Also, the confused torque split computer allowed some wheelspin high in the rev range in first gear. Still, the handling was so much better than standard that I stuck with this mod for some time. Then it rained. The predictability and stability that the car had in the dry was immediately gone. Not that it was as bad as I'd found it in standard form, but it just didn't feel quite right and straightline wheelspin was even more pronounced.

By this stage two more important things had happened: I'd had a chat to a bloke who had been involved in the Bathurst race GT-R's, and my tame electronic guru (thanks Dad!) had developed the third version of the G-sensor adjustable amplifier. This was being used to slightly reduce the output of what (with the G-sensor rotated) was now the lateral sensor.

The ex-Bathurst race team man said something that immediately caught my attention. "The computer reduces the front torque split the harder you corner. So if you remove the influence of the lateral G-sensor, the car will go into four wheel drive earlier". Gulp! I'd always figured that the computer would increase the front torque split as you cornered harder. That's why I'd initially tried to amplify the signal - I should have been trying to reduce it all along! "One way to do this is to feed a constant 2.5 volt signal to the computer input for the lateral G-sensor" he continued. "Course, it understeers like a pig then" he added.

Even Better

I raced out to the car and effectively returned it to standard, but for feeding a constant 2.5 volt input lateral signal to the computer. He was right - with this mod the car did understeer excessively. But that was in the dry. In wet conditions this modification made the car just ballistic - unbelievably good, with so much traction and cornering prowess that it was uncanny. The difference was so immense that in the wet conditions I found myself ABS'ing up to roundabouts, so good was the car's grip in every other situation.

Okay - if holding the lateral G-sensor input fixed at 2.5 volts gave too much front wheel drive in the dry but was perfect in the wet, why not use the amplifier to vary the lateral G-sensor signal from 1:1 (ie signal unchanged from the standard voltage swings) right through to 0:1 (ie signal fixed at 2.5 volts input)? In other words, be able to change the influence of the lateral G-sensor all the way from factory standard to none! That way I'd be able to dial up any cornering torque split from huge oversteer right through to heaps of FWD for wet conditions.

And that's just what the final configuration is like. A knob on the dash allows variable selection across the whole range. The knob is calibrated from 0-10, with 0 being standard and 10 being for full wet weather. Generally I'm around '7' in dry conditions, with '6' being used in really tight low speed corners when I want the tail to come out a bit to turn the car in. When the road gets wet '8' or '9' is selected, and when it's streaming with water I'm a '10' man!

Set up in this way the handling is absolutely fantastic. It's hard to believe, but the electronic mods have made more difference to the handling of the GT-R than any other suspension modifications I have ever made to a car. And that includes the changing on previous cars of wheels, tyres, sway bars, springs, dampers, bushes - the lot. The difference simply cannot be overstated. And I might add that now the cat's out of the bag, a number of GT-R owners who had previously told me how wonderfully their cars handled have modified their torque split control system...

Now with the car handling as well as it does I reckon I could do with a bit more power..... stay tuned!

Tech Summary:

Skyline GT-R R32 Torque Controller Modifications

Some R32 GT-R Skylines have pronounced power oversteer. The degree of oversteer varies from car to car. If the driver has driven only rear wheel drive cars previously they are less likely to recognise a problem. The oversteer is at its greatest in wet conditions.

Modification to the electronic torque split control system can make a massive difference to the degree of power oversteer or understeer.

There are several ways in which the system can be modified. Quite different results can be achieved by the different modifications.

Simplest is to rotate the G-sensor module through 90°. The G-sensor is the gold coloured box located under the centre console, in the very middle of the car. Rotate it by 90° and fix it in its new position. Advantages: results in a far higher degree of front wheel drive torque split in cornering conditions; is the easiest of all modifications. Disadvantages: results in some wheelspin in straight-line acceleration at high revs; power understeer can occur; in wet conditions the car is still a little unpredictable. Summary: Gives an easier car to drive but isn't the ultimate mod.

With the G-sensor orientated as factory, disable the output of the lateral (cornering) G-sensor. This G-sensor input actually reduces the front wheel torque split as cornering loads increase. Cutting the wire results in a fault condition and the disabling of the four wheel drive and ABS systems. Instead, 2.5 volts needs to be constantly fed to this ECU input. This can be achieved by using a voltage divider (pot) as shown here. The pot should be carefully adjusted until 2.5 volts output occurs when it is connected up. Advantages: very large amount of front torque split in cornering; simple mod; superb in wet conditions; excellent straight-line traction. Disadvantages: excessive power understeer in dry conditions. Summary: great "wet weather over-ride" if switched in and out appropriately.

With the G-sensor orientated as factory, use an amplifier circuit that allows variation of the magnitude of output swing of the lateral G-sensor. This involves feeding the output of the lateral G-sensor into the amp and then the output of the amp into the ECU input. A dash-mounted potentiometer allows adjustment of the gain. As shown, the circuit allows a gain of 1 times (ie factory output signal retained) right through to 0 times (ie output stays at 2.5 volts irrespective of input voltage swings). Advantages: best of all worlds - with knob adjustment, excellent dry road handling, excellent wet weather handling, excellent straight-line traction. Disadvantages: requires extensive knowledge of electronics to build and calibrate amp. Figure 2 shows a suggested amp circuit. Note that the designer of this amplifier has stated "This circuit cannot be employed as the basis of replication with randomly chosen LF411 ICs because the voltages shown are optimum for the particular op amps used." Also note that the designer is not interested in producing any more amplifiers. Summary: just superb!

G-sensor Pin-Outs With G-sensor in Standard Orientation

Note: initial colour code refers to wiring on the sensor side of plugs; after semi-colon refers to colour code on the ECU side of plugs.

Large Plug

Yellow; blue/green longitudinal sensor output (2.5 volts at rest)

Blue; blue/yellow lateral sensor output (2.5 volts at rest)

Red; white/blue regulated supply (8 volts)

Black; orange/blue earth

Brown; black braided earth

Small Plug

White; red longitudinal sensor output (2.5 volts at rest)

Red; white regulated supply (8 volts)

Black; black earth

Brown; black braided earth

All three G-sensors have a 2.5 volt output at rest. Under acceleration conditions, the voltage swings at least as high as 4 volts or at least as low as 1 volt (depending on the direction of acceleration).

http://us1.webpublications.com.au/static/i...0/0060_10mg.jpg

http://us1.webpublications.com.au/static/i...0/0060_09mg.jpg

Edited June 16, 2006 by mazgtr

[Duncan]

Hi ebloa, I'll be interested to see your results Its always good to see new ideas in the area.

The guy who puts our ones together has done a heap of development over the years, which is how we ended up with a microprocessor instead of direct reduction of the output.

Also you should be aware ATTESA is not designed to give constant front torque you will definately have trouble, the clutch packs will give out within an hour

[mazgtr]

Yeah Duncans right, most of the aftermarket Attesa controllers simply adjust the speed and time front torque is apllied and when.

I think the old HKS drag controller used to be able to "pre-load the front wheels, but this was only every intended for drag aplication IMO.

[ebola]

I have read the autospeed article - which is how I knew it was powered from an 8v source. Thanks though, mazgtr.

I don't see how the broad minded personch packs would wear out if there is no slip (though there would be in the snow, which is why I had the idea). I guess when turning there would be a difference, though.

Duncan's attesa controller appears to be the same solution as the autospeed article (op-amp based), but controlled by a microcontroller (with a few extras thrown in as well).

What I was thinking of was not just a variable resistor in line with the sensors, but replacing the sensor output alltogether (to begin with), and then (If can be bothered pulling my car apart) seeing if I can give a 'voltage preload'.

Though as has been pointed out, this would be pretty hard on the clutch packs (Is the attesa hydraulic pump able to stand long periods, as it wasn't designed for it).

I'll upload a circuit diagram when a) it works, or b) it smokes.

Thanks for the help though.

nK

nicholas Krul

[Duncan]

We have never had a problem with the pump even when running a lot of front torque for a long time, eg wet targa stages, instead the clutches in the case overheat and fail first. Good luck with the development.

[ebola]

Development - I wish. Better with ideas than execution, like so many people in life.

The only reading I got was 30 mA - I should have been doing it with a printout of that article next to me.

The package was neater than I thought.

I should have know to expect something more like a package and less like I do things in a production car.

I was a little concerned to find that the abs seems to want the G-sensor output as well. pulled the plug, and, well, abs light went on. A little dodgy to me - and it puts the risk factor back up.

How hard is it to get a hold of a set of (full - large and small, male & female) plugs, so that I can interface b/n the computer and sensors and not risk stupid slips with my precious car?

for that matter duncan, how does your (professional) unit interface - does it use plugs, or is it a case of wire and solder. I'll check the fs thread again tomorrow. not tonight.

I think I'll wire up a DPDT switch into the 10K pot circuit for now, and go back to the drawing board.

========================================

related issue - now that I have found that the G-sensors are needed for ABS, I don't want to disable the attesa that way anymore. There is the tried and true method of a switch inline with the engine bay fuse (pulled it for drifting - attesa only), but you have to stop the car for that.

Has anyone considered putting a switch inline with the solenoid for the attesa pump? The theory being that you won't have to come to a complete stop to turn it back on.

Thanks again. I am sure that most of my ideas will have already been 'had' (and chucked out), but there are some odd ones too, that just might work. or at least I think (and hope) so.

nK

[Duncan]

Yeah we just cut the signal wire and either solder or use crimp connectors - we supply connectors with the kit for ease but personally I prefer the solder. Narva or whoever they are do sell plugs now, ina whole heap of different wire numbers but thats more relevent if yo uhave to keep plugging and unplugging not a one off install....if you've ever seen an alarm install you will see they have no magic in their connections either.

BTW its not my unit, I can just get hold of them for SAU at a good price, I have used them for years and the guy I race with helped with the development, but all the real work was done by someone else - so I am not sure of all the detail or trial and errors.

Re the ABS there is at least 1 signal that comes via the ATTESA unit, may have been wheel speed I am not sure off the top of my head - but every way I have seen of disabling ATTESA also kills ABS on a GTR. The switch on the pump power is interesting, let us know how it goes if you try it.