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Pumpkin drop event

Are "expo" settings used with a quadrocopter?

dalaman

Junior Member
#1
I'm in the process of building the electrohub spider quadrocopter and want to know if "expo" settings are used with this build. I've been flying airplanes now for 2 years and using expo but this is my first quad build. I did buy a Blade Nano to practice on but I didn't see anything in the directions about using expo. Just asking...
 

Snarls

Gravity Tester
Mentor
#3
If you do chose to have expo I think it's recommended that you do it through your flight controller's GUI if possible rather than through your TX.
 

joshuabardwell

Senior Member
Mentor
#4
Lots of pilots use expo on a multirotor. Throttle expo especially is nice because you can have lots of resolution around your hover point, where you need to make very precise inputs. If you go with expo, it's better to do it on the FC rather than the transmitter. The FC can apply the expo internally, making for minimal resolution losses. If you apply the expo on the transmitter, you lose resolution. Does it matter? Debatable. There may already be more resolution than you actually need. But it's best practice.

The only time I have used expo on my transmitter was when I wanted to apply negative expo to just the yaw channel. My FC doesn't seem to support this, so I did it on the transmitter.
 

dalaman

Junior Member
#5
Lots of pilots use expo on a multirotor. Throttle expo especially is nice because you can have lots of resolution around your hover point, where you need to make very precise inputs. If you go with expo, it's better to do it on the FC rather than the transmitter. The FC can apply the expo internally, making for minimal resolution losses. If you apply the expo on the transmitter, you lose resolution. Does it matter? Debatable. There may already be more resolution than you actually need. But it's best practice.

The only time I have used expo on my transmitter was when I wanted to apply negative expo to just the yaw channel. My FC doesn't seem to support this, so I did it on the transmitter.
Sorry, but I'm not sure what the "resolution" really means. Could you explain? Thanks!
 

joshuabardwell

Senior Member
Mentor
#6
I'm not sure I can write a concise explanation of resolution without getting into a whole bunch of information theory that is probably too complicated for the actual question that was asked. In short, you want to push your processing as late in the signal chain as you can. So you want the transmitter to send an unmodified signal to the FC, and then have the FC do the processing (expo) on the signal, rather than having the transmitter modify the signal and then send it to the FC.

Honestly, the concern is probably somewhat overblown. I did some basic testing with my transmitter, and the transmitter already has far more resolution than my poor fingers can really use. In other words, if I was looking at the channel monitor screen, I could very carefully move the sticks so as to get a 1 us change in the output value of the channel. But I could never reliably re-create a value with even close to 1 us precision under real-world conditions. So if some resolution is lost, I probably would never notice.