Hi
I like flying fast rc models, can you please tell me the max speed a model can still be stabilized with the Ardupilot mega?
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Hi
I like flying fast rc models, can you please tell me the max speed a model can still be stabilized with the Ardupilot mega?
You need to be a member of diydrones to add comments!
Replies
For what I have learned a fast plane can be stabilized by a 50hz refresh with a simple pid control like the one on apm, at least it is the same refresh of our std radios so you can implement a code to make it do that in the right way. Just don't ask too much (too near waypoints, too small radius, too quick maneuvers).
I'm not aware of a limiter for the gforce induced by the autopilot, so a fast plane with lot of throw control can go into a strong gforce when you are tuning the pid by trial and errors, unless there is a limiter and I don't know about it.
I'm sure that lot of people use the funjet with apm, can someone post his high and avg speeds so we can have some numbers?
I still wonder what is the refresh rate of apm (I'm planning to buy it but actually I run on my own code on arduinopro),
if apm use a standard 25ms ppm frame it can't run (if it does is absolutely useless) over 40hz. even at 40hz in the next frame the servos are only starting to move to the previous sent position so he is calculationg based on a wrong feel by the sensor.
To me this a good reason to think that apm is not suitable for really fast maneuvers and/or corrections (that is different than fast planes).
One simple way to see this is to make a video of the roll resonance induced by the apm, the quicker it is the quicker is the control loop. I really wish too see this! on an easyglider or cularis the best because are my 2 platform.
I really wish to know more about that and have real data because those are speculations that I'm making while choosing if I have to buy or not the apm. His slowness is my main concern because I fight against that a lot with mine. Actually I'm so quick that had to write some code to avoid to burn my aileron servos (It happened, servo was so quick reversing that motor burned even if on 5V only, you can't do this with ppm even if you try because 40hz reversing is accepted by servo, I was reversing it much quicker).
I mounted the imu on the servo arm to see where I can go. in flight is different because you have airframe inertia helping to slow things, with fast reacting planes maybe it could happen with fast code like mine. don' want to terrify anyone, with my easyglider it was impossible to burn it but on a dive I melt some cables when it reached the resonance on roll. Emax 9g digital servos, I melt the long cables in the wing that are not cooled in any way, on the ground I warped the wing and they made a short.. I never read about this with apm so I think that you are not going so fast.
Anyone want to make some try? :)
One thing to note, the navigation control loop in the mega beta processes at a rate that is not high enough to fly real jets with with the default waypoint radius of 30 meters. What this implies is that if your model is going fast enough, it can "miss" the waypoint and will go into an orbit around it due to a roll limit of 30 degrees.