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Old Mar 26, 2012, 06:16 PM
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Al Ducharme
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Orlando, FL
Joined Jan 2005
735 Posts
Quote:
Originally Posted by Arx View Post
While that's probably true, there are some differences between the reflashed and stock ESCs, and it seems pretty hasty to just dismiss the reflashed ones as no better than stock. If it were that simple, Simon would be kind of a dumbass to be wasting his time writing firmware.

There are differences that go beyond what the test you're doing can resolve, and some of them are quite evident in peoples empirical testing (Definitely not just their imagination).

That's not to say that your measurements are wrong, or useless, just that it's not quite as simple as your original post implies.

Keep up the good work on this stuff, just don't throw away everyone else's testing and experiences as invalid.

With that test with the bouncing motors, I believe the "throttle range" was pretty much just controlled by a servo, I interpreted that bouncing as oscillation due to the lag. Sure, the gain might just need to be tweaked downward to stabilize it as well, but that is undeniably a useful result. That said, I don't really understand what the deal was with the 3rd one.
What I would really like to do is find a solid repeatable test that allows us all to drive the ESC vendors.

I don't disagree that the video is interesting but I would like to figure out a way to measure and document what is really happening.

I agree with your previous comments about TF by definition being applied only to LTI systems. It almost never is actually, typcially assumptions have to be made concerning the regimes where the measurement is linear. I chose 25% based on many other tests. I have done the tests for other values such as 5% and 10%. I'll post more results.

What I would really like to do is find a good test case, two ESCs to compare. I'll measure it with my test stand and others can also measure the same two. Then let's all decide.

My intuition is that the momentum of the propeller limits realistic update to about 50Hz with very very minor corrections up to 100Hz. Changes in RPM greater than 10% can only occur lower than 30Hz.

I don't disagree with comments like "well it just flies better with X brand ESC" I disagree with "feel" being representative of fact which seems to be the prevailing sentiment.
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