Slip/launch control on MoTeC

Original thread from BMWSG forums:

One of the unique features of the Heffner Twin Turbo Vipers is the AEM management system. Heffner is the only Viper tuner to use an engine management system to regulate the boost and fuel for the twin-turbo set up. One main advantage of this is that lower boost can be run at certain times to make the car drivable on the streets. It's one thing to build a 1000 horsepower car, but an entirely different accomplishment to build one you can actually drive on the street. In theory, the more horsepower you have the better, but actually driving a car with this amount of horsepower on the street can be quite difficult and many times dangerous. Here's a helpful hint: if your car can lose traction at 100 mph or more when you give it too much gas, then you should probably stick to the drag strip. With the AEM system, however, boost is regulated until the wheel speed increases enough to make the car drivable at any speed. Heffner has allowed horsepower freaks to have their cake and eat it too.

I would call this a boost/fuel compensation map(s) based on wheel speed which is nothing special. On a turbo car such as this Viper you lose "anti-lag" abilities, since boost is regulated. A better way would be to introduce gradual ignition cut based on calculated wheel slip in conjunction with a rev limit.

Compensation Channel Assignment

Here is how I would implement such a system in a MoTeC setup. First, assign the wheel slip voltage to be a compensation channel for both fuel and ignition. Note the number of possible channel sources; there are more than 50 possible sources to choose from.

Channel Assignment

Next, assign wheel slip voltage to a pin so the ECU knows what it is.

Sensor Calibration Table

Now we need to calibrate the ECU to read the sensor. 0V means no slip, 5V means 100% slip.

Ignition Compensation Table

This is the ignition compensation table. Right now it's set up so that if there's 50% slip, then we introduce a 50% ignition cut. No slip means no ignition cut so the car can continue to put all its available power to the ground. If it's slipping 100%, then just cut ignition totally. Sensible and straight-forward. It's just as easy to set up the fuel compensation table.

Traction Control Function (advanced)

For ECUs with advanced functions enabled, this screen allows a whole lot more parameters to be set up so we can skip all those previous steps.