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#1 kapteinkuk May 26, 2010 04:58 AM

ESC Response Testing
 
I have tested a few different ESC's for throttle response time, that is, the time from full throttle given to the ESC gives full motor power.

Note that the test starts a low throttle (running motor), not zero, so the start up delay is not included.


http://static.rcgroups.com/forums/at...G?d=1272643964

This scope screenshot shows a turnigy plush 30a ESC's response to a instaneous increase in throttle from low to full. (1.1 to 2 mS at 50Hz PPM)

Red trace: motor current.
Yellow trace: PPM signal

http://static.rcgroups.com/forums/at...g?d=1272490216
100Hz.

A doubling in PPM frequency halves the ESC's response time, thus makes it possible to use higher gain, and therefore making the quad more stable.

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.

http://static.rcgroups.com/forums/at...g?d=1272490216
200Hz.

http://static.rcgroups.com/forums/at...g?d=1272490216
400Hz.

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

HK 10A: 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


I will update the list as I get my hands on more ESC's

#2 dcaspi May 26, 2010 05:27 AM

I believe the response time, at least for the Plush I have, is programmable. Which setting did you use?

Dror

#3 elossam May 26, 2010 08:22 AM

Are these tests done with the engine loaded with airscrew or not?
This graphics show i.e. the difference in engine response when using a simple ESC conected to a std receiver vs. the use of a ESC based in I2C like the ones of mikrokopter and others or the I2C has nothing to do here?
Any other ref about the Unknown #1: 80mS unit?

#4 rimshotcopter May 26, 2010 10:28 PM

Not sure I am understanding here, of the ESCs tested, which one has the best response time?

thank you.

#5 kapteinkuk May 27, 2010 07:14 AM

Quote:

Originally Posted by dcaspi (Post 15174451)
I believe the response time, at least for the Plush I have, is programmable. Which setting did you use?

Dror

I have tried every setting. Still the same response.

#6 kapteinkuk May 27, 2010 07:21 AM

Quote:

Originally Posted by elossam (Post 15175212)
Are these tests done with the engine loaded with airscrew or not?
This graphics show i.e. the difference in engine response when using a simple ESC conected to a std receiver vs. the use of a ESC based in I2C like the ones of mikrokopter and others or the I2C has nothing to do here?
Any other ref about the Unknown #1: 80mS unit?

Tests is done with propeller. However, the response is the same without.

This has nothing to do with PPM vs I2C. It is simply the time elapsed from the ESC has recieved throttle change, until new power output from ESC is reached.

It also excludes RPM delay due to inertia. This is only the delay internal the ESC.

The unknown unit is a Jeti Advance 8A according to the owner.

#7 kapteinkuk May 27, 2010 07:28 AM

Quote:

Originally Posted by reverendrichie (Post 15180781)
Not sure I am understanding here, of the ESCs tested, which one has the best response time?

thank you.

The shortest time is the best, currently the 80mS unit.

Shorter delay means faster response in the whole system.
System is: gyro -> FC -> ESC -> motor -> propeller -> aircraft inertia

#8 rimshotcopter May 27, 2010 07:31 AM

Quote:

Originally Posted by kapteinkuk (Post 15182598)
The shortest time is the best, currently the 80mS unit.

Shorter delay means faster response in the whole system.
System is: gyro -> FC -> ESC -> motor -> propeller -> aircraft inertia


Thank you

#9 cyborgcnc May 27, 2010 07:40 AM

Thank you very much for doing this testing kaptein!

VERY useful information!

What software are you using, and what PC scope?

#10 jesolins May 27, 2010 07:54 AM

Rolf,
Thanks for sharing this info. Along with the response time you measured, how do the number of steps an ESC has factor into the final quad control smoothness?
HKSS and Mystery ESC's are good PWM performers for quads too as well as being good I2c modification candidates. The Mystery ESC's have the very friendly quad and tricopter feature of being able to completly disable the LVC.
Cheers,
Jim
Quadrocopter and Tricopter Mega Link Index

#11 dcaspi May 27, 2010 08:42 AM

One important conclusion about control loop rates:

There were debates on the Quaduino and other threads that discussed controller software, about what sampling frequency of the control algorithm is required for stability. some even exaggerated and said that 1000Hz is required. My own experience has shown 100Hz to work very well.

Now, if the response times are 80msec or slower, then I would guess you could safely reduce to loop rate to, say, 30Hz with no impact!

Dror

#12 tritan May 27, 2010 11:41 AM

As I have 3 of the Jeti Spin 22 I would very much like to know the response time of these. The manual says it can be programmed down to 200mS.

Tritan

#13 outsider787 May 27, 2010 11:48 AM

Keptein,
Interesting figures you've discovered for full throttle response.

It's not often that full throttle is given from a low rpm.

If only part throttle is given, is it safe to assume an equivalent fraction of the response time is needed?

So if only 1/10 of throttle adjusting is needed, can it be assumed that the response time is 1/10 of full throttle response to achieve the adjustment?

#14 kapteinkuk May 27, 2010 05:28 PM

Quote:

Originally Posted by cyborgcnc (Post 15182648)
Thank you very much for doing this testing kaptein!

VERY useful information!

What software are you using, and what PC scope?

The scope is a Owon PDS 5022, borrowed from a friend.

#15 kapteinkuk May 27, 2010 05:35 PM

Quote:

Originally Posted by jesolins (Post 15182715)
Rolf,
Thanks for sharing this info. Along with the response time you measured, how do the number of steps an ESC has factor into the final quad control smoothness?
HKSS and Mystery ESC's are good PWM performers for quads too as well as being good I2c modification candidates. The Mystery ESC's have the very friendly quad and tricopter feature of being able to completly disable the LVC.
Cheers,
Jim
Quadrocopter and Tricopter Mega Link Index

Are you thinking of number of throttle steps (resolution)?

I was thinking of number of steps (PPM pulses) for the filter to reach final throttle value. It has no impact on smoothness.


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