The Phoenix Documentation says that to tune kF, we need to measure the maximal velocity of the mechanism. However, we fear doing so will break the mechanism because it does not have a lot of room to move. Is there a way to tune kF without reaching the peak velocity of the mechanism?
Thank you!
Detach the chain, remove a gear, unhook a belt. Decouple the motors from the mechanism. Check the max speed of just the motors. Take half of that and start there. Create a variable that records the speed of the motors while you are moving your mechanism after you have put you gains in place. If you are hitting that top speed, then you set your value low. Increase it a little bit at a time until you don’t hit it, then you know you’ve found your top speed. Of course - this is related to your acceleration value. Start low and work your way up.
This is exactly how we are doing it.
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The best thing to do is to slowly ramp up the voltage while logging voltage and velocity. Perform a linear regression of velocity versus voltage, the resulting slope is your kF gain.
You’ll also notice that the intercept of said linear regression is nonzero - alas, there is no way to properly account for this with only a kF gain - you’d have to use arbitrary feedforward.
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