Discussion and questions related to the course Launch Control
How would you be able to properly set up ground speed launch control on an AWD vehicle?
Unfortunately you can't since there is no reference for ground speed. This is discussed in the body of the course. It's possible to potentially use a high speed (50Hz minimum) GPS sensor but there aren't too many ECUs that are compatible with this option for a launch control strategy unfortunately.
As Andre said use GPS or dont use speed based and use a time based strategy from your launch switch release.
To follow on from this, what sort of sensors are you guys using for this? Racegrade (Motec USA i am told) make it seems a 20hz sensor, but samples at 50Hz? not being an expert in GPS it is hard to understand. This is the sensor that Shane T uses on his 4wd custom firmware kits. A bit of back ground I have this going a circa 2000hp 4wd vr38 240Z I am currently completing, it is a bit off but I have most of my electronics package on a 500kw S15 to play with all the traction control and anti lag strategies and would like to set it up on this to play first.
Is the Racegrade the fastest known kit right now at 20hz?
I've done Traction Control on 4wd using the Race Technology SpeedBox, It uses inertial sensors to calculate speed, and offsets the drift with a GPS signal.
The real problem with GPS isn't the update rate, it's the calculation delay. In other words, GPS speed calculation tell you how fast you were going 50ms ago. A little late for many traction control strategies -- but better than nothing. By using inertial data (integrating accelerations to determine velocity), you can get a faster response.
There is a 50hz and soon 100 hz GPS from eTesta that you might consider: http://etesta.com/new/etesta-gps7.html