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Old Feb 19, 2013, 02:09 PM
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The ultimate multirotor motor response?

Why is not regenerative braking more widely used in the multirotor community?

The plot below shows a motor response without braking:
Name: No braking open loop.jpg
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And then the same setup, but now the motor control uses regenerative braking. And closed loop rpm control:
Name: Regenerative braking closed loop.jpg
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The difference in speed decrease is significant from regenerative braking. And at least in this testcase greatly accentuated by closed loop rpm control.
Further results and data on the testing can be found here: Regenerative braking and ...

The test also shows that since active freewheeling is a part of the regenerative braking, the motor runs equally efficient whether running braked or nonbraked.
It just responds much faster, which should allow for significantly higher flight controller PID gains and more stable flying, more agile response, better wind tolerance etc.
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Old Feb 19, 2013, 03:24 PM
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pretty sure simonk uses regenerative braking?
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Old Feb 19, 2013, 04:17 PM
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pretty sure simonk uses regenerative braking?
To my knowledge, setting the COMP_PWM option in the SimonK code is the equivalent of using "damped light" mode on damped capable ESCs in BLHeli.
For SimonK also supported for some ESCs, but is it widely used?
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Old Feb 19, 2013, 07:08 PM
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Originally Posted by sskaug View Post
To my knowledge, setting the COMP_PWM option in the SimonK code is the equivalent of using "damped light" mode on damped capable ESCs in BLHeli.
For SimonK also supported for some ESCs, but is it widely used?
While there are probably some people using it in the SimonK code I'm fairly certain the majority aren't, I know I haven't set it on any of the reflashed ESCs I currently have in use.

I am willing to put it to a test though. I have a couple sets of Silabs based ESCs on hand that I was just about to update with BLHeli, just finished and tested the first one before dinner. I have a DJI F450 frame setup with a Multiwii flight controller and older Atmel based Turnigy Plush using SimonK code. I know how it flys and what the power consumption is with this setup, what I'll do is setup 4 of the Silabs based ESCs set to "damped light" if that is the proper setting to use and see how it compares changing nothing else on the quad but the ESCs.

Now its over to the workbench to flash 3 more ESCs...
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Old Feb 21, 2013, 02:24 PM
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Do you use SiLabs ESCs that support "fully damped" mode? The reason I ask is that there are two ways of handling damped light mode, for details see page 17 here: https://github.com/bitdump/BLHeli/bl...x.pdf?raw=true

If your ESCs do not support fully damped mode, then you will not have the benefit of active freewheeling. And also your motor may not run smoothly, especially at high damping force. Here you can see which ESCs support fully damped mode: https://github.com/bitdump/BLHeli/bl...s.pdf?raw=true
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Old Feb 21, 2013, 10:00 PM
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Originally Posted by sskaug View Post
Do you use SiLabs ESCs that support "fully damped" mode? The reason I ask is that there are two ways of handling damped light mode, for details see page 17 here: https://github.com/bitdump/BLHeli/bl...x.pdf?raw=true

If your ESCs do not support fully damped mode, then you will not have the benefit of active freewheeling. And also your motor may not run smoothly, especially at high damping force. Here you can see which ESCs support fully damped mode: https://github.com/bitdump/BLHeli/bl...s.pdf?raw=true
The ESCs I'm testing with are the DJI 18 and 30 amp Opto which are the same as Hobbywing/Turnigy. I have flashed both sets with the corresponding BLHeli Turnigy versions and set the options using the BLheli tool. When I did the original reflash I left an external connection so I can change options or reflash with the ESCs in place. In the limited flight testing I've been able to do so far it does seem to make a noticeable difference in windy conditions.

I need to do a lot more testing but so far it appears to work well set to light damping, at the very least it doesn't seem to have any negative effect that I can see.
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Old May 10, 2015, 11:37 PM
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Quote:
Originally Posted by sskaug View Post
Why is not regenerative braking more widely used in the multirotor community?

The plot below shows a motor response without braking:
Attachment 5550607

And then the same setup, but now the motor control uses regenerative braking. And closed loop rpm control:
Attachment 5550608

The difference in speed decrease is significant from regenerative braking. And at least in this testcase greatly accentuated by closed loop rpm control.
Further results and data on the testing can be found here: Attachment 5550610

The test also shows that since active freewheeling is a part of the regenerative braking, the motor runs equally efficient whether running braked or nonbraked.
It just responds much faster, which should allow for significantly higher flight controller PID gains and more stable flying, more agile response, better wind tolerance etc.
How do you generate the graph? is the rpm measured from a sensor or the esc?
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Old May 10, 2015, 11:41 PM
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Originally Posted by dschafer View Post
How do you generate the graph? is the rpm measured from a sensor or the esc?

You do know the thread is over 2 years old right?
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Old May 10, 2015, 11:57 PM
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You do know the thread is over 2 years old right?
Sorry I'm new, thought it might be monitored.
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