Acceleration based on position

[Ether]

Let XU be the upper position limit.

Let XL be the lower position limit.

Let X be the current position, between those limits.

Let K be the size of the "speed zone" near either limit, where speed gets reduced.

Let J be the joystick command, between -1 and +1, where +1 commands a speed toward the upper limit.

Then:

if ( (X>XU-K) && (J>(XU-X)/K) ) J=(XU-X)/K;
else
if ( (X<XL+K) && (J<(XL-X)/K) ) J=(XL-X)/K;

[Greg McKaskle]

If you reverse your decision and want to use PIDs, you may want to consider joystick control where some input takes the elevator between a few known height set points -- say floor, lower peg, feed slot, middle peg, upper peg.

For more control, if the driver presses and holds a button, the joystick value is sent directly to the motor. OR you can make it to where this mode changes the set point.

Greg McKaskle