I don't see a datasheet from an original manufacture stating it's designed to work at other then 'standard' servo update/pulse width control.
Many of the servos are analog: it takes the pwm pulse train through a low-pass filter to derive at a voltage signal (to be compared with a position sensor's output). Because of such, a higher pwm frequency will always work - but a lower frequency may not.
I take such statements as not understanding the question. The site said one must first test a servo for higher framing rates, why would they state such if higher pwm frequecies 'always work'?
I don't see a datasheet from an original manufacture stating it's designed to work at other then 'standard' servo update/pulse width control.
I was suprised when I started looking for datasheets for ESC's that I couldn't find any specification of the update/pulse width. The only thing I could find was Castle Creation (one of the top brands of ESC's) has announced an upgrade to their firmware that should make their ESC suitable for multirotors.
So I could ask the same question to retrolefty:
How do you know that the standard servo update/pulse is within the specifikations when there is none. ? <- smiley
I think (I presume) that this standard servo specification goes back to the good old happy days of ppm TX/RX.
AFter we have got all the pcm/spcm/spread spectrum technic it seems like vendors are more relaxed about the specifications.
I don't see a datasheet from an original manufacture stating it's designed to work at other then 'standard' servo update/pulse width control.
I was suprised when I started looking for datasheets for ESC's that I couldn't find any specification of the update/pulse width. The only thing I could find was Castle Creation (one of the top brands of ESC's) has announced an upgrade to their firmware that should make their ESC suitable for multirotors.
So I could ask the same question to retrolefty:
How do you know that the standard servo update/pulse is within the specifikations when there is none. ? <- smiley
Because a ESC sold with a standard servo control connector strongly implies that it is suitable for the 'standard' variable pulse width and frame rate specifications that the R/C hobby has been using for many decades now, unless they stated otherwise in their datasheet. As such I would not assume any operation far from that 'standard' timings unless also documented in their datasheet.
I think (I presume) that this standard servo specification goes back to the good old happy days of ppm TX/RX.
Of course, that's my point. This thread is about using R/C type ESCs at frame rates well above that 'R/C standard' which seems to be possible via hand testing of some units from some manufactures. I question was really about OEMs documenting/verifying operation at other faster framing rates.
AFter we have got all the pcm/spcm/spread spectrum technic it seems like vendors are more relaxed about the specifications.
That's a start, that would mean they are rating their device able to support up to twice the framing rate, maybe other OEMs will also start documenting such specifications.
And although there has been numerous complaints with this system, if have not heard of any having trouble with their standard ESC.
maybe other OEMs will also start documenting such specifications.
Or maybe this is one of those cases that you are presumed to have known that. Turning on a computer is vital to you programming your arduino yet you see no mentioning of turning on your computer in any arduino book.
That's a start, that would mean they are rating their device able to support up to twice the framing rate, maybe other OEMs will also start documenting such specifications.
No that is the output framerate from the receiver. My point is that you connect this to a standard ESC !
I have found these X-BLDC Brushless motors and ESC's.
These motors are made by an exclusive team, from what I have heard, in Germany, and have ESC's on I2C working at 1Khz, and 14-pole brushless motors.
Here's the link:
What do you think about this? Is curious, because I see no datasheet, they don't write anything about their products, and somehow they are selling them. (From what I have heard, these systems are custom made, and by this, their products are so expensive).
This I was asking you.
I don't know nothing but the interface speed. Nothing more.
Yes, they are exaggeratedly high priced, from my point of view, and even I don't know if they are good at something.
My goal is to make something like those from the MIT, or if it is possible, even better. I know that their quadcopters (from the MIT) have ESC's running at 1Khz, and I believe that the only way of reaching their performances is to match their physical quadcopter's characteristics, thus I need this type of ESC's and motors.
My goal is to make something like those from the MIT, or if it is possible, even better.
It is possible and likely.
The avr based esc is practically in the public domain and you can find everywhere. Many firms offer public domain mcu-based BLDC controller code that you can adapted to AVR, or any other chips you wish to use.
Having said that, bldc control is actually quite complicated. Without good understanding of analog / digital electronics, I suggest that you don't set too high of an expectation for yourself.
Because bldc controller is such a huge market and one that is naturally gifted for mcus, all MCU manufacturers have numerous app notes on them. Atmel has quite a few, ST has a fairly well written and documented library on BLDC control for its stm8 and stm32 chips. That would be where I start.
The undisputed king here is Freestyle but unfortunately they write cryptic app notes on this.
And because ESC's are mass produced and therefor relatively cheap, and many are based on Atmega8, there are many tutorials to reprogram an existing ESC to do what you want.
Now regarding the BLDC motors.
What is more efficient in terms of performances, responsiveness and torque? The 2-pole motors or having 3 (to 8 poles)?
From I think, having more poles, you'll need higher frequencies between the ESC and the motor, therefore more precision at controlling the motor. IS that right?
<- smiley