About TC in corners

[bernif2003]

I've been watching some laps onboard on difrent drivers and cars, of the 3 first races of the season. And last friday I went to the Barcelona tests.
And hearing the sound of this videos, and the test specialy the TC, you can see how the TC helps to steer in the exit of the corners.
I would like to know how the software knows how it has to actuate on the wheels. By measering the position of steering, the lateral/long acceleration,...?¿?¿ Does anybody knows how does the TC works exactly?
Maybe the driver just push the trottle and turns the steering wheel, and the TC does the hard work.
thanx

[Guest]

From what I know, TC applies the maximum amount of power available to the wheels, according to grip levels. It becomes easier to accelerate out of corners because the chances of spinning out are significantly less. Look at what FA did with his Renault in Monza 2003 - TC shut off, he spun quite unceremoniously.

TC doesn't give you more grip, but makes sure you can apply the right amount of power at a given level of grip, to make sure it's not too much.

[Becker4]

how does it know what is too much though? sensors in the wheels? when does the software know that a lack of traction is imenent, and how does it find this out, and how does it stop it?

[SimplyFast]

the software has been developed with the latest mathematical figures of how many g's a car can pull into/out of the corners. it has meters to read the g force applied, corrects accordingly.
this is from what i understand anyway.

[marcush.]

it is quite easy,sort of ...you just compare wheelrevolutions front and rear ,as in areas where you need tractioncontrol you woul´d not necesssaryly apply the brakesso if the rear wheels accelerate above a certain level faster than the front wheels you cut back on torque available by giving less preignition,
(if you have a tough engine)or cut out some sparks.The level of cutback can be easily dialed in .
Would a good traction control lead to different setups?I´m not really sure about that one you could go more on a knife edge that is for sure and the TC lets you live better with a understeary/oversteary car,as in the first you just reduce the engine cutback and in the second you give more tc,so it is a vital tool to trim the car in the race on corner exit.
If you see cars using lots of TC it doesn´t speak well of the rest of the car in my opinion.It would be much better if they produced enough grip to handle the loads without such a device,but that is an oversimplification.

[bernif2003]

I meant that the TC can be set up for each corner. It may help you to exit of that corner, not only reducing the spin of rear wheels, but giving a little level of spin, and making the car oversteer.
And I think that it can't be done with measuring the speed of the front wheels.... It must be so much dificutl and complex.

[scarbs]

There are two types of TC, the usual sort we expect the limit wheel slip which works by detecting the differential speed between the front and rear axles, These wheels speeds are picked up by sensors on the front uprights reading the revolutions of the brake disc carrier and at the rear by a toothed sprocket on the driveshaft output flange. When the management unit detects more a specific percentage of slip over a specific speed then an algorithm decides whether to limit the ignition, fuelling, throttle opening or whatever parameter to control wheelspin. A specific percentage (round 5%) of slip is required as the tyres work best in that region, and the TC only cuts in over a certain speed (over only a few miles an hour).
This basic TC only takes into account the limit of longitudinal grip, if the car is cornering then lateral grip (going back to the friction circle concept) can beaten up by slip and the oversteer spin out of a corner. To counter this TC-LAT (for lateral TC) is used, this detects over steer via accelerometers front and rear, detecting a slide and limiting power output with a similar algorithm to basic TC. Using TC-Lat effectively allows the driver to open the throttle past the optimum position (they don’t just floor it) and the electronics keep the car at a set level of oversteer. It is this type of TC that is most often heard out of a corner. Adjustment for both types is often on the steering wheel, and allows the driver to dial in the level of oversteer they prefer. From this position the teams can set up an idealised map of TC setting for around the lap.

[Racer-X]

It can also be done measuring how quick the engine revolution increases. If it increases to quick it means you loose traction. It is the engine acceleration derivative.

The cars also have a pitot tube over the car in front of the drive to measure the real speed of the car which can be compared to the wheels speed and identify if there is a loss of traction.

[bernif2003]

Thanx Scarbs! Good explanation!
Do you know if they have a diferent set up of TC for each corner, memorised in the software, and it goes changing the set of TC automaticaly?

[scarbs]

I beleive via either GSM positioning or the telemtry memory that adjustments per corner are in use for some teams, but I have also heard it not always used in the race..!

[Guest]

one stupid question guys,

what about coordination between TC and differential ?
anyone has an idea ?

thanks

thejhn

[marcush.]

I do not see where the difficulty is to use the the difference in acceleration of the wheels as an indicator of wheelspin.
As soon as you have lateral accelaration at the back you had oversteer ,no grip available and positive acceleration of the wheel.
As scarbs stated ,if you are at the edge of maximum grip ,the tyre cannot transmit more force so if i have maxim7um forward accelarion the car will have no grip left to tackle the carnering forces,the car will oversteer .
So of course the easy system measuring the difference in gain of wheelspeed front to rear is able to control oversteer characteristic as if you would not allow for the max slip longitudinalthere is some grip potential left to cornering the car,and less oversteer.

[scarbs]

I wouldnt doubt that the diff may be used as part of the TC strategy, but I was once told that F1 cars tend to spin both wheels rather than just one, removing the need for alot of diff control. Also the rules do not allow the diff to be altered from steering inputs, whether it can react to lateral accelleromter readings is debatable

[marcush.]

if you ban using the brakes to help steer the car (what they did)then you obviously have to ban traction control as a help to steer the car two....so tc is illegal except when you go straight forward.

[Reca]

The cars also have a pitot tube over the car in front of the drive to measure the real speed of the car which can be compared to the wheels speed and identify if there is a loss of traction.

I always had a doubt about that. Pitot measures speed relative to air, the difference with speed relative to ground could be enough to make the measure useless for the TC. Furthermore Pitot tube was there also when TC wasn’t legal, so it’s probably used for something else, or at least, also for something else, maybe to measure density or maybe the degree of yaw relative to air.
I never was close enough to a Pitot tube on a F1 car to see how many holes there are on the lateral surface (to measure static pressure), someone knows ? Scarbs ?