Scaling Values in the Control Program

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Posted by Nate Smith.

Other on team #66, GM Powertrain/Willow Run HS, from Eastern Michigan University and GM Powertrain.

Posted on 3/15/2000 6:09 PM MST


In Reply to: please explain more... posted by Joe Johnson on 3/15/2000 10:39 AM MST:



: Nate,

: Please explain more what you are trying to do and what happens when you try doing it.

: It is not clear what 'scale down' means. It is equally unclear what 'lose part of the range completely' means.

: More details will mean better help.

: Joe J.

For those of you who have seen our machine in action, you know about our hook delivery arm for grabbing onto the bar. The extension and positioning functions of that arm are controlled by the X and Y axes of the joystick on port 3. The positioning function was judged to be too quick by our drive team at EMU, so we want to scale the joystick value for that axis down 50% before outputting it to the speed controller.

As for losing part of our range, when I attempted to scale down the drive train output to 50% of the joystick value in order to create our 'turbo boost' function, using the code shown below:
(for forward)
p1_yfilt = (p1_yfilt)/2 min 128 max 254
(for reverse)
p1_yfilt = (p1_yfilt*3)/2 min 0 max 126

in one direction, i would lose all output unless the 'turbo' function was on, and in the other, it would always act as if the turbo was turned on.

Looking at mike's code, that might work...will have to try it and see what happens...

Nate