Programming for a Shifting Gearbox

[apalrd]

Since it's in the code release anyway, I guess I'll write out the shift conditions we used. Assume that we Abs all of the inputs first so there's no directionality differences.

Any shift auto shift:
-No shift in last 500ms
-Stick differential threshold limit to prevent shifting while turning (for tank drive skid steer). This is pre-Abs of throttles.

Upshift (power-on upshift):
-Throttles min (already in ft/sec) 20% greater than shift point FPS
-Acceleration of throttles not negative (with some deadband for noise)
-Wheel acceleration rate greater than constant
-Output speed greater than shift point

Downshift (kickdown):
-Gearbox output speed < 8fps or so (slightly higher than or equal to our peak speed in the lower gear)
-Throttles > 80%
-Wheel acceleration rate is negative and below a constant (vehicle is rapidly decelerating)

Downshift (coastdown):
-Gearbox output speed < 2fps

We don't do any special execution of the shift. Once we have decided to shift, we set the pneumatic solenoids and are done for at least 500ms.