Stand Alone Traction Control Module

[baadgn]

Oh boy - Donnie's going to build his own TC. That should be an interesting 1000 page thread!:tongue:

I agree 100% about the safety aspect. I had considered adding it on my green car just for the safety however I'm not sure any TC unit can save a water leak, oil spill or just plain stupidity.

In this particular case it may help with stupidity, when there is so much of it

 

[Dusty Bradford]

Oh boy - Donnie's going to build his own TC. That should be an interesting 1000 page thread!:tongue:

I agree 100% about the safety aspect. I had considered adding it on my green car just for the safety however I'm not sure any TC unit can save a water leak, oil spill or just plain stupidity.

The brain and the right foot is the 1st line of defense. I see way too many guys at the track that stay in the throttle much longer than they should.

 

[Alky V6]

Oh boy - Donnie's going to build his own TC. That should be an interesting 1000 page thread! (just kidding Donnie) :tongue:

I agree 100% about the safety aspect. I had considered adding it on my green car just for the safety however I'm not sure any TC unit can save a water leak, oil spill or just plain stupidity.

Don't worry. If I decide to do this, I won't be sharing it.
Nothing personal. There are some things I don't bother sharing details about.

 

[Alky V6]

The brain and the right foot is the 1st line of defense. I see way too many guys at the track that stay in the throttle much longer than they should.

I agree. By far that is a common reason. But, I'm also seeing more videos these days where the car gets out of shape so quick, I can't see anyone reacting quick enough to have made a difference.
Davis claims his system can start making tire slip corrections within one quarter turn of the driveshaft. No human being can match that. I don't know if a system that reacts that quick is absolutely necessary, but it sure would make me feel a lot more confident on a pass, and I would hope the fella next to me is also running a similar system.

 

[Alky V6]

Notes from another thread

Good stuff I thought I'd paste here for future reference.

HighPSI - That might work fine for street driving, but I am skeptical of how well it would work on a drag car that can pull the wheels. I suppose, having diferent size tires could be worked around.

DonWG - That would be something that can be programmed into the TC module or sub routine. Front wheels see so many pulses per revolution, rear wheels see so many pulses/rev during normal straight line driving.
Or, front wheel sees so many pulses/rev, driveshaft sees so many pulses/rev during normal straight line driving.
A timer can be programmed off the transbrake to ignore the first 1.xx seconds of the run.
Or, a certain acceptable amount of slip can be programmed for that same time period. That way, you could program in when in the run you want the front tires to touch back down.

HighPSI - Based on my experience with traction control, that won't work very well. Gary Harmon's TSL car get's around one wheel rotation in the 60' where the traction control is most needed. Since they launch softer, the DR cars do get a little more front wheel speed, but nothing that is consistant enough to calculate off of. I personally would consider using another method than comparing wheel speeds.

DonWG - What if front wheel speed was ignored for a time during the launch and only driveshaft acceleration rate was looked at? Then once a certain front wheel speed was seen, then it would convert to front wheel speed vs. rear wheel speed, or driveshaft speed?

If we're going to continue this TC line of thought, how 'bout we move it to the TC thread?

 

[Alky V6]

In a staight line traction control situation, what kinds of different monitoring or methods could be used to affect TC? Lets assume that a spool is being used, so we will only need one rear wheel sensor, or driveshaft speed sensor.

Monitoring
One rear wheel speed sensor
One driveshaft speed sensor
Engine rpm speed sensor
One of two front wheel speed sensors
Ground speed sensor
GPS
Radar

Comparisons of monitored variables
Driveshaft or drive wheel speed relative to ground speed
DS or DWS relative to front wheel speed
DS or DWS acceleration rate relative to time
DS or DWS acceleration rate relative to time relative to particular transmission gear ratio
Engine speed to DS or DWS
Engine speed to DS or DWS to trans gear ratio. Ramping curves.
Many more...

Methods of TC
Throttle control. Stepped or ramped.
Engine ignition timing control. Stepped or ramped retard. Pattern ignition cut.
Boost control. Stepped or ramped.
Fueling control. Pattern fuel cut.
Brake control.

 

[Alky V6]

Types of speed sensors.
Magnetic
Hall Effect
Optical

One of the sensors I'll be dealing with will be a two wire magnetic vehicle speed sensor sensing a 40 tooth reluctor wheel on the output shaft of the transmission.

The magnetic speed sensor is also known as an analog AC signal generator. As speed increases, the amplitude and frequency of the signal from the sensor both increase.

The magnetic speed sensor is sensitive to electromagnetic interference (EMI) or RF (radio frequency).

 

[HighPSI]

What if front wheel speed was ignored for a time during the launch and only driveshaft acceleration rate was looked at? Then once a certain front wheel speed was seen, then it would convert to front wheel speed vs. rear wheel speed, or driveshaft speed??

If you are going to ignore front wheel speed at the most critical time traction control is needed (first 100'), why even bother using a front speed sensor down track? Just use the same method all the time.

I am geting the impression you are wanting to use the traction control as a safety item more than a performance advantage.

 

[Alky V6]

The analog signal from the output speed sensor will need to be converted to a digital signal so that a microprocessor can use it.

 

[Alky V6]

If you are going to ignore front wheel speed at the most critical time traction control is needed (first 100'), why even bother using a front speed sensor down track? Just use the same method all the time.

I am geting the impression you are wanting to use the traction control as a safety item more than a performance advantage.

There's no reason TC can't be used for both. It may involve a mix of different strategies to accomplish that goal.

 

[Alky V6]

Jumping to the end process. In my particular case, engine ignition timing retard would be used to control driving torque. The TEC unit has a GPI that will accept a 0-5V or 0-12V. The amount of timing retard can be varied by a ramping 0-5V signal. Anything past the 5V up to 12V will just give the max timing retard specified in the parameter. The input range of the timing retard parameter is 0 through -30 degrees. If -20 degrees is input, then the timing retard will ramp from 0 degrees at 0V to -20 degrees at 5V on the GPI.

 

[Alky V6]

I should be able to supply an adjustable ramping voltage signal from the TC module to the TEC unit using a potentiometer and capacitor on the ouput side in the TC module.

 

[Alky V6]

Pros and cons of the different control strategies.

It's been presented to me that retarding the ignition timing on a turbo car might not be the most effective or safe way to get TC. If timing had to be retarded too much, it might create dangerously high exhaust temps (exhaust valve temps). I'm burning alcohol, so I wonder how that would play out.
I agree that high exhaust temps should be avoided, but if the degree of needed retard to affect TC could be controlled, I wonder how effective just small amounts of timing retard would be.

 

[Alky V6]

I'm not sure how cutting fuel to cylinders using a batch injection system would work. What if you only cut half the amount of fueling to a cylinder? Would the danger of lean backfiring be possible? Burning alcohol?

 

[Alky V6]

Ignition cut with large amounts of fuel could results in some fantastic exhaust side backfires or high exhaust temps.

 

[Alky V6]

I think I'll stick with timing retard for now.

 

[Alky V6]

Building the module

First problem.
Converting the analog speed sensor signal to a digital signal.
http://www.allaboutcircuits.com/vol_4/chpt_13/1.html

 

[hiboom]

tc

I know on my late model cars both rear wheel and front wheel drive the tc tries to correct tire spin by applying the brake to the wheel thats spinning I have a 06 Monte SS with the 303 hp ls4 fwd when the tc kicks in it kills the ignition and tries to put the brakes on if you don't have your seat belt on it about throws you into the front windshield LOL!

 

[Dusty Bradford]

Pros and cons of the different control strategies.

It's been presented to me that retarding the ignition timing on a turbo car might not be the most effective or safe way to get TC. If timing had to be retarded too much, it might create dangerously high exhaust temps (exhaust valve temps). I'm burning alcohol, so I wonder how that would play out.
I agree that high exhaust temps should be avoided, but if the degree of needed retard to affect TC could be controlled, I wonder how effective just small amounts of timing retard would be.

Use the timing retard. If the car is having to pull dangerous amounts of timing out to control wheel spin, the boost curve needs to be changed.

For example. You can't have 35psi of boost in .5 seconds and let the tc do all the work. If the tc is having to pull it down to less than 10*, pull some boost out of it.

 

[Alky V6]

Use the timing retard. If the car is having to pull dangerous amounts of timing out to control wheel spin, the boost curve needs to be changed.

For example. You can't have 35psi of boost in .5 seconds and let the tc do all the work. If the tc is having to pull it down to less than 10*, pull some boost out of it.

I agree, Dusty. TC should be used more as a fine tuning tool. Not a crutch because someone didn't bother to build a proper boost control curve.