<<ESC response rate driving motor speed changes that makes the difference and most ESCs currently available are not optimized for fast response>>
Great info. So what is this ESC response rate? Is there a spec. for such thing? Is it the physical hardware or firmware?
I'm tired of not understanding settings etc. that benefit multirotors.
Thanks again for the info.
The ESC response rate is how quickly it can take commands to change speed that come from the flight controller and turn it into an actual speed change at the motor. Multirotors are unique in that they have to be continually making quick adjustments to the speed of each motor to maintain level flight, the faster that occurs the more stable the multi is. Most ESC have some form of filtering built into the firmware to smooth the speed change response in some manner, on many high end ESCs like Castle there are a lot more programming options available to make the response more suitable for helis vs. airplanes but none yet that offer what a multirotor needs.
The closest you can come to a multirotor optimized PWM ESC is to take one of Atmel processer based units and reflash it with SimonK's firmware that removes the features not needed for use on a multi and sets some important parameters to the best settings that the hardware is capable of. There is a noticeable difference when using this code but it's not without issues of it's own, namely it's the efforts of one person and occasionaly a bug turns up in the code that can have serious consequences, like causing a motor to stop while in flight.
So mainly the problem is in the firmware, it is possible to take the current versions of hardware and use modified firmware to get an ESC better suited to use on a multi, however it is very much a "do this at your own risk" proposition. That said, many of the more recent ESCs coming out of China have been built around a Silabs processor which appear to be a bit better for multirotor use but still have the same limitations in the firmware. There is currently no alternative firmware available for these although some people are working on developing code similar to what is available for the Atmel ESCs.
None of this is anything that is published by any of the manufacturers, it's not something that anyone has been particularly interested in until the recent boom in multirotor popularity. There are some efforts underway to develop specialized ESC for our use, most notably the OpenPilot group at the moment, but it won't be until one of the big manufacturing houses starts producing them in large quantities that they will something you'll be able to buy with a few clicks of a mouse. When or if that will happen is anyones guess.
Ken
