Thread: Discussion ESC Response Testing View Single Post
Dec 09, 2010, 03:06 PM
Registered User
France
Joined Nov 2003
287 Posts
Quote:
Originally Posted by pando14
You right..I completely forget rampdown (stepdown) response
With "rampdown"(up) do you mean stepdown(up)? however rampdown(up) is simply a lot of step one after another so maybe you can simplify your test doing:
-just one shot 10 - 100% ---> wait RPM adjustment (100ms could be too little) ---> just one shot 100 - 10%

-just one shot 50 - 70% ---> wait RPM adjustment (100ms could be too little) ---> just one shot 70 - 50%

Quote:
 I wrote you this things because the final objective is to find the best ESC response (isn't it?) and in your previous graphs i can't understand it clearly because i can't understand time scale (i think because there are too much pulses so time scale become smaller or maybe because I can't read it). So maybe a simply step (up and down) response can show it better.
In previous graph, the X axes was time. Between each PWM change there is 50, 100 or 300 msec depending on the graph. So you don't need much to bother with the time, it is only interesting to know that time between PWM pulse is constant.

[QOUTE]
One measure every 25ms (40Hz) seems to be not enough because time responses in kapteinkuk's graph are:
1) 137ms with big pulse and 50Hz pwm
2) <25ms with big pulse and 400Hz pwm
To clarify what is measured, every 25msec the number of hits (magnet in front of the sensor) is returned. Below 25msec, the number of hits become fairly small, and approximation increase. There are 6 magnets on my motor, the accuracy is 1/6 turn. It may worth trying below 25msec. I looks there is no direct mapping between current consumption and RPM...
Quote:
 With 1measure every 25ms we can capture 5-6 points on rising (falling) edge of the RPM behaviour in first case and no one in the second case. With smaller pulse (like 50-70% ), the rising edge (falling) time response will be even more little!
At highst turn rate, the motor speed approximately 10000 RPM (to simplify). It means 166 rotation per second, so 0.166 per msec. 25 msec is 4.16 turn.
Ok, may be it could be reduced down to 2turns at full speed, which is 1 turn at half speed, so 12msec would be worth trying.

Quote:
 Maybe the motor inertia could help us and delay time response but i'm a little bit doubtful..what do you think about this?
Some people have emit doubts about the fact that no propeller was used during that test. So, "with propeller" is to add to the test list.