True. But I think it's reasonable to buttume some nominal value for rolling resistance and brake drag. If the vehicle is, for example, on a long gravel hill or if the brakes are malfunctioning, I wouldn't (as an owner) expect a downshifting algorithm to function flawlessly.
Also, if the surface has high rolling resistance or dragging brakes, the vehicle might not need to downshift (though dragging brakes could quickly lead to the sort of thermal problem a downshift algorithm helps to avoid).
I haven't tried to write one of these routines myself, but if I had to start tomorrow :-), after each start I'd reset the buttumed payload to driver only, then observe.
If the vehicle was heavily laden and the car started downhill, the estimated (downward) grade would be too high and the trans would downshift early. The driver would apply more throttle than my algorithm would expect, and the algorithm would use that information to adjust the mbutt estimate upwards (slowly) until the driver's throttle application was consistent with the grade estimate.
I'm sure it's trickier than I expect, but I'm still pretty sure it can be done with enough fidelity to be more help than hindrance. -- Chuck Tomlinson
Why Manual Transmissions are superior 4335I liked the simplicity of the old Beetles, which is why I owned three of 'em at one point. They were air cooled (actually oil cooled to be precise) which means you never had...
