View Full Version : Launch Control

12-30-2003, 03:30 PM
Hey, like to thank everyone again for the input regarding the TCS. Looks like i've got a winning module right now, BUT I'm trying to integrated a launch control into it, primarily so I don't wind up with fifteen little black boxes duct taped to the frame! Anyone have any advice on how to rig the launch control, and how to hook up a gearshift indicator? I know how to run a display, but i'm not sure how to sense what gear the tranny is in...

any input would be appreciated. Thanks,

"They say time is of the essence... give me some and maybe i'll get the essence!"

12-30-2003, 06:05 PM
how are you planning on implementing all these controlers? if you are using a microcomputer, then sensing the position of the "gear barrel" (sorry, dont know the correct term/mental blank. the barrel with the grooves in it that swaps the gear cogs) would be a good way of determining what gear you are in. a potentiometer would work, but i dont know if your microcomputer can take resistance as an input. maybe a rotating switch?

btw, if you are using a microcomputer, what sort and what language do you use to program it? just curious.

- the problem with the world is stupidity. i'm not saying there should be a capital punishment for stupidity, but why don't we just take the safety lables off of everything and let the problem solve itself?

B Lewis @ PE Engine Management
12-30-2003, 06:50 PM
Hi Axle_Greese,

How are things going at ODU?

If you have TCS working than launch control is just a subset of that. The only other piece that you need is to be able to run up against a secondary rev limit when at the line and the clutch is dis-engaged. You can use a digital output and digital input in tandem with the PE-ECU-1 ECU to do that.

As far as the gear indicator, try using a pot as the last post suggested. If you are building your own display that will be able to take a serial data stream, we can provide the protocol to you for the ECU. Then you can just use one of our analog inputs with your gear select pot and then that data will be also be sent back and forth along with temps, RPM, pressures, etc. Let me know if you need any help.

Brian Lewis
Performance Electronics, Ltd.
www.pe-ltd.com (http://www.pe-ltd.com)
"Complete Engine Management Systems for $798"

01-06-2004, 08:51 AM
I think i have everything under control now as far as the launch control goes, and I found a specific circuit online for a gearshift indicator that reads the stock sensor, so that should be easy enough to build up. (I just got a chance to talk with our engine guy yesterday after the holiday) BTW, we are REALLY happy with the ECU ;-)

Insofar as the TCS and the Launch control go, I am using only one digital chip in the entire system, which is roughly the size of a keyless entry remote. The remainder of the system is completely analog, allowing for infinite adjustment for slip, as well as drop-in upgradeability to StabiliTrack-style braking systems. There are no microcontrollers, no analog to digital converters, just six IC's on a board with some adjustment potentiometers and a power supply. If anyone is interested in implementing the system, I'd be happy to provide it to you for a small fee! (Hey, a guy's gotta eat, right?)

"They say time is of the essence... give me some and maybe i'll get the essence!"

B Lewis @ PE Engine Management
01-06-2004, 08:49 PM
Glad to hear you are happy with the ECU. I am interested to see your setup in action at Pontiac. Hopefully for you guys it WILL rain.

Brian Lewis
Performance Electronics, Ltd.
www.pe-ltd.com (http://www.pe-ltd.com)
"Complete Engine Management Systems for $798"

Cement Legs
08-16-2004, 09:58 AM
For our gear indicator we are just counting up and down with successfully recorded shifts, but it seems you have found a better way! In one of your earlier posts you mentioned that there is a built in gear position sensor, does this sense all gears or just neutral? What type of signal comes from this sensor?

Daygo Nighthawk
08-17-2004, 10:53 PM
If you look at the very bottom/middle of the picture, you can see half of the end of the shifter cam. You can see the ball end screw (looks like MIG splatter) that is our shift toggler. I believe the engine comes like this in stock form, to trigger the bike's neutral switch. We simply made a piece that goes over the end of the shifter cam, and has 7 microswitches instead of 1. Voila, triggeredness. http://fsae.com/groupee_common/emoticons/icon_smile.gif
We use a single digit LED to display the gear number.
Hope this helps.

Launch/Traction control is still a dream for us right now.. maybe a project I can research later, when I have time.

08-23-2004, 01:55 PM
Mouser electronics carries digital selector switches. You rotate the switch through say 3, 10, or 20 positions and four wires coming out of the switch provide a binary number (paralell). You can hook this up directly to a BCD display driver, and you've got yourself a gearshift indicator. There are various versions of the switch, but essentially it's a really stripped down shaft encoder. Probbably mechanical, as opposed to optical like old-school mice. (pop out the ball and see the little wagon wheel with an led next to it)

08-24-2004, 04:07 PM
we're using a rotary pot that we have added to the shifter drum and then used an AtoD converter to display gear. Another way, not as good, is the way MOTEC does it by using the gear speed, driven wheel speed and known ratios. It works OK and doesn't require any internal engine mods to get the pot on the shifter drum.

12-14-2005, 11:19 PM
I have a few questions concerning timing and frequency error.

How often do you update your wheel speeds? Do you do it fast enough to detect slip within the span of one engine rev? With my specifications, I would like to update the percentage wheel slip every 4 milliseconds but that doesn't seem like an option at low speeds.

What are the uncertainties in your tooth frequency measurements? +- 1Hz etc.?

Homemade WRX
01-09-2006, 11:17 AM
don't ask us we are still forced to use our feet...let's just say axle greece fell through

07-03-2006, 06:35 PM
good launch control is a lot more than just a secondary rev limiter

10-09-2006, 05:49 AM

So who as a working launch control and how did you do it.

We are thinking about building one too http://fsae.com/groupee_common/emoticons/icon_smile.gif