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Old Dec 15, 2010, 02:06 PM
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Solihull, England
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Try using as a dc motor (not a can type) driven as a generator to act as a tacho for speed measurement. Use the best quality you have with a multi-segment commutator.

Peter
Quote:
Originally Posted by obor View Post
I agree with you if the rampup(or rampdown) is reached before the next PWM duty. If not, then the way firmware handle rampup or down may interfere.


Yes, you are right, with small PWM period changes like 50ms, the RPM capture every 25msec is not accurate enough.


I agree with this, with small period like 50msec ,measurement are not accurate enough. But do we need to measure that low ? I did 100 msec measurement, but could try also 150 or 200 msec between PWM changes.

If we consider that it takes approx 4msec for a turn a full speed, then with 6 magnets it gives:
- in 4 msec, Magnet seen vary between 0 - 6
- in 8 msec, it gives 0-12
For RPM varying between 2000 and 3000, that means 0-3 to 0-4/5 in 4 msec, which 1 or 2 magnet more or less per turn, which is not enough.
I'll try to double the number of magnets.
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Old Feb 14, 2011, 01:19 PM
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What happened to all that. żAny news in the last two months?
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Old Feb 15, 2011, 11:08 AM
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No news. Running out of time.
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Old Feb 15, 2011, 12:07 PM
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This is very interesting data. Thank you for taking the time to do the testing.

One thing I would like to see is a real world test. Basically a test to verify the ESC response speed and effect on stability. Someone that has a proven vehicle that they have flown many times could run the test. Fly with the slowest response ESC's and the fastest response ESC's and collect video and accelerometer data. It is important that the only variable be the different ESC.

I think the real world test is important because at some level of response there will be no improvement to flight. I'm sure this will be different for different size vehicles but at least we will have one data point. Hopefully others could test and provide more data for different size vehicles.
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Old Feb 27, 2011, 10:51 AM
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Quote:
Originally Posted by kapteinkuk View Post


This ESC and most other I have tested uses a finite response low pass filter based on the PPM frequency, on the throttle. The filter has 7 steps at the biggest difference in the throttle, less at smaller differences.
Hi, kapteinkuk!

Thanks for sharing the results of yours tests.

The picture above shows that the ESC responds "instantaneously" when throttle is reduced to zero. Does that mean that the ESC only applies the FIR filter when throttle is increased? Or maybe that bringing throttle to zero is a special case for which the ESC just bypasses the FIR altogether?

Thanks!
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Old Jul 05, 2011, 08:48 PM
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I don't have a fancy current measuring setup so I just probed low-side from power supply GND to ESC's GND, so there is a bunch of noise in the measurements, but the pictures confirm what kk had going:

Turnigy Basic 25A:


HKSS 20A reprogrammed with simonk's improved firmware


You see the similar "ramping" as visible in kk's screenshots of Turnigy ESC with default firmware, and a much faster ramp with modified firmware.
I kept time division same in both screenshots, but moved the current measurement a bit up in the 2nd one. Input is throttle channel from FrSky D8R receiver.

Note how original turnigy takes almost 5*20ms periods to finally ramp up to setpoint rpm.

One thing to note, this was done without prop (I don't have a motor test bench so I had to hold it in hand while holding probes and trying to push "stop" on my scope too.

I might repeat this later when I get a current sensor and also try results at 400Hz instead of 50Hz
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Old Aug 26, 2011, 12:01 PM
gr8
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Finland
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obor can you share your arduino code?

I have similar testing hardware with Dueminalove and Hall Effect Sensor taken from old pc cooling fan. Luckily i found this thread as here's some good information and tips to look at!

-Jani-
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Old Sep 26, 2011, 11:04 AM
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Old Jan 05, 2012, 06:49 PM
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Sorry to dig up an old thread, I have only recently become aware of this ESC response issue, for some reason I always thought that the ESC electronics would be way faster than what is required by the FC/motors, that's obviously not the case. My main interest is for getting the best out of twitchy little mini-quad designs. Does anyone have a list of the response times for a variety of popular ESC's people use for quads?
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Old Mar 04, 2012, 06:39 AM
Did you get it on video?
Flying-Monkey's Avatar
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Joined Nov 2005
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The first post listed these...

Tested ESCs response time at 50Hz:

Unknown #1 (99% sure it is a Jeti Advance 8A, according to the owner): 80mS
Notes: very good

Turnigy Plush 30A: 137mS

Turnigy Plush 10A: 137mS

Turnigy Plush 6A: 137mS

TowerPro H40A:: 137mS

HK-HW30A: 137mS

Turnigy K-Force 40A: 175mS

Waypoint 15A: 200mS

Turnigy Super Slow Brain 20A: 200mS
Notes: Response time is constant regardless of PPM frequency. Uses a constant time base for the filter, not the PPM frequency.

Otter BS 40A: 390mS
Notes: Also filters high to low throttle

Hyperion 10A: 490mS

Are you asking for an updated list? (I noticed the first post hasn't been revisited since sometime in 2010.)
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Old Mar 04, 2012, 06:54 AM
Tri-Quad-Hexa-Octo-copters!!
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Joined Feb 2007
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Gents,
Currently the best fast PWM ESC results for multicopters is the Quax/SimonK firmware. From the ESC recommendations and converting ESCs to I2c and to faster PWM in the Quadrocopter and Tricopter Info Mega Link Index:

--TIP 11: For faster ESC PWM update rates for use on most current flight controllers that output ~400Hz update rates, it is recommended to flash Quax/SimonK ESC firmware to take advantage of the higher performance. You can DIY per the Fast PWM links such as Nek's SimonK fast PWM firmware thread, or order the ESC's specifying that you want the fast PWM loaded from Ken in the USA at www.quadroufo.com , or Timecop in Japan at www.abusemark.com , or Dan in China at http://www.multircshop.com/site/inde...product_id=627.

Cheers,
Jim
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Old Apr 05, 2012, 07:04 PM
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I tested 3 versions of the Plush 10A:

Old with AVR micro-controller:


New with SIL micro-controller:


And finally the old with AVR, flashed with Simonk (TGY.HEX):


The last one gives a near instant response, can not get better than this. So now I am going to wade through my old crap, looking for plush'es with an AVR!
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Old Apr 05, 2012, 07:21 PM
Tri-Quad-Hexa-Octo-copters!!
United States, TX, San Antonio
Joined Feb 2007
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Hi Rolf,
Thanks for the great ESC performance data! It is certainly easy to see the differences between the firmwares.
Al from Hoverfly started yet another thread on this here. Your insights and repeatable testing data would be an asset there too. http://www.rcgroups.com/forums/showthread.php?t=1620724
Cheers,
Jim
Quadrocopter and Tricopter Info Mega Link Index

Quote:
Originally Posted by kapteinkuk View Post
I tested 3 versions of the Plush 10A:

Old with AVR micro-controller:


New with SIL micro-controller:


And finally the old with AVR, flashed with Simonk (TGY.HEX):


The last one gives a near instant response, can not get better than this. So now I am going to wade through my old crap, looking for plush'es with an AVR!
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Old Apr 05, 2012, 08:52 PM
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Canada, BC, North Vancouver
Joined Dec 2010
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Quote:
Originally Posted by kapteinkuk View Post
And finally the old with AVR, flashed with Simonk (TGY.HEX):
Hi, kapteinkuk! Incidentally, what is the peak of that current when scaled from shunt voltage to actual Amperes? Cheers
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Old Apr 05, 2012, 09:05 PM
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Joined Feb 2007
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That what I was thinking about... looks like top current is 3 times more then with OEM firmware.
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