The Effect of Top-End CleanFlight BLHeli Throttle Calibration
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- เผยแพร่เมื่อ 12 เม.ย. 2016
- Is top-end Cleanflight or Betaflight BLHeli throttle calibration worth it? Does it actually improve anything? Yes. In this video, you'll see the actual gyro data that shows how top-end throttle calibration affects multirotor performance.
Cheers Joshua,
Interesting results from your analysis there! I enjoy your videos and how informative and helpful they are. I don't mind you waffling on 👍 keep up the good work on the videos 👌
Excellent work , thanks.
Thanks Joshua! This helped clear my confusion. Do you have any insight as to why raising min_throttle is fixing the uncommanded roll issues? I've solved my issue by help on the Betaflight forum. I had to raise mine up to 1060 (my motors spin at 1030) and it fixed my issue. I'm just not sure why.
+Chris E if min_throttle is too low, the motor will stop spinning in the air and the copter can lose control. Setting min_throttle on the bench doesn't take into account the dynamic loading that can occur in the air. Imagine that you are at idle and falling. The air rushing upwards through the prop is pushing it to slow it down. If that is going fast enough, the prop can stop spinning. When you hit the throttle hard to arrest the fall, the copter destabilizes. Depending on motor startup strength (BLHeli setting) the prop may not get going again, but it shouldn't have stopped in the first place.
If you set min_throttle to the absolute lowest value on the bench, in the air it can be too low.
+Chris E I have a theory that you may be able to set min_throttle lower if you increase the startup power in BLHeli. Increased startup power means that when the motor does briefly stop, it will get going again more decisively. I haven't tested this though.
+Joshua Bardwell Ill have to test that out. Maybe it has something to do with size of motors too? I'm using sunnysky 2207 2100's, 35g each. More mass takes more power to start? I'll have to pay attention to who else is having same issue and what they are using.
Chris E Definitely the motor and prop size plays into the needed power to start the motors. I would expect larger motors to need a higher min_throttle all else being equal.
Joshua Bardwell channel is like 2-4 unwatched "walking dead" series every day :)
+fpvYou I'll take that as a compliment.
+fpvYou It's watched by me. For me it's easily in the 2 channels with the most valuable content on youtube, along with Bruce.
Nice analysis and explanation. One idea if you do this again: instead of using data while throttle is at max, you could us data while one of the motor commanded outputs is over a threshold.
+Chris Mavrakis That's a good idea. If I was really, really clever, I could Excel the data to select when any single motor output was over a threshold.
wonder how much of that peak is also due to a higher step of throttle generating vibration as opposed to oscillation caused by deadband
+Stephen Wright I don't think that's the case because the higher throttle step is not resulting in higher rpms.
how do you know this? Does that mean no rpm difference=no thrust difference? If thats the case I will not bother with that last step...
+Stephen Wright I know this because I used the Motors tab to spin up the motors and determined that above that value there was no increase in rpm. From QuadMcFly's testing, I can see that BLHeli has a similar plateau in thrust at the top of its curve. He also confirms that the plateau in rpm corresponds to a plateau in thrust. Based on all of this, I feel reasonably confident saying that the method I outlined determines the practical top end of the throttle curve.
Your questions are valid, though. I do think that more confirmation that max rpm = max thrust with prop on would be valuable. For example, spin the motor with the prop off and determine the point of max rpm. Then spin the motor with the prop on and do the same. Then measure the point of max thrust with the motor on. Are these values all close to the same, or do they differ. Between myself and QuadMcFly, I think we have done all of these tests, and they seem to agree, but I don't think any one person has done all of these tests, all at once, on the same ESC/motor/prop combination, to be 100% sure that they correspond.
Nice!
Curious if you felt any difference in flight
+Justin-Rey Baltazar (JRey) I think so, but too soon to tell. There was little discernible difference during straight punches, but I think the copter felt more controlled when doing high-throttle maneuvers like sharp turns.
+Joshua Bardwell I just calibrated too. My punch outs feel ever so slightly smoother and acro at full stick position is the same. Might be placebo. But I do feel better knowing I have less oscillations (potentially)