[tomy]

so the best and easiest way is the way you described in post 16

Do this in your encoder intiialization:
distancePerPulse = (wheel_diameter*PI/pulses_per_revolution)*gear_ratio;
leftfrontEncoder->SetDistancePerPulse(distancePerPulse);
leftrearEncoder->SetDistancePerPulse(distancePerPulse);
rightfrontEncoder->SetDistancePerPulse(distancePerPulse);
rightrearEncoder->SetDistancePerPulse(distnacePerPulse);

Then do this in your autonomous loop:
double distanceTraveled = (leftfrontEncoder->GetDistance() +
rightFrontEncoder->GetDistance() +
leftRearEncoder->GetDistance() +
rightRearEncoder->GetDistance())/4.0;
if (distanceTraveled < 60.0)
{
MecaumDrive_Polar(forwardPower, 0.0, 0.0);
}
else
{
MecaumDrive_Polar(0.0, 0.0, 0.0);
}