Quote:
Originally Posted by Jared341
The method of adding the two outputs that you propose will work (and work well once the loops are tuned). The limitation of what happens when one drive side is saturated (e.g. can't go any faster) is a problem - as you noted.
The simplest/best strategy for dealing with this problem in my experience is a function which detects this case and adjusts both outputs (left and right) to ensure that the proper ratio between left and right drive power is maintained, while neither output exceeds +/-1. Note that it helps to have a linear response curve before doing this (e.g. use Jaguars, or write a linearization function for your Victors). If you look at the newly-posted 2011 Team 254 code, you will see code to deal with this scenario.
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Now you're just being mean, digging up linearization from my 14 years ago system class
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I remember the basics - create a function that modifies your input so that the output becomes linear. However I'll be darned if I can remember the process, and every online source starts digging into calculus that I haven't touched in 20 years.
So, I'll turn to practical methods.
Step 1: Plot the labview input (x) versus victor output voltage (y) measured with multimeter to define a non-linear curve.
Step 2: Create two columns: "Labview input to victor" and "Required input to linearize output".
3: Populate columns in excel, by estimating values off my graph, then apply a best fit line to get a polynomial equation that relates the required labview inputs to the actual, such that F(Actual labview input) = Required Labview Input.
Now tell me there's some nice clean mathematical way to do this in fewer steps and more accurately (where's Ether when you need him - this is right up his alley)....
