ArduCopter motor command and take-off issues
Hello team,
Thanks for all the support thus far on building my first arducopter.
Yesterday, I had finally completed the frame, uploaded the recent ArdupiratesNG code, calibrated my ESCs, checked motor directions, calibrated the TX through configurator, calibrated accel sensors, etc.
It seemed as if all was ready to go, so I prepared for a pre-flight check with no props and armed the motors. (I have Xbees enabled and relaying data back to configurator wirelessly). Immediately, configurator showed the 4 motors jump from "1040" to "1100" (motors not spinning). This seemed correct as the quad was now armed.
Now heres the trick, As I increased the throttle to say around 20%, at first the Front and Rear motors would increase to about 1200 but then drop down to 1100 and stop running. At the same time, the other 2 motors (Left and Right), would continue to gain power until the reach around 1400.
Now I tried increasing throttle to 50%, and a similar situation occured. This time, the Front and Rear motors reached around 1450 before they started dropping back down to around 1200 (Spinning but Low RPM). The other two motors (Left and Right) continued to gain power until they reached around 1750.
My first reaction was to check trims (which were all 0), and recalibrate, but to no avail. It seems as if the quad is trying to overcompensate for a shift in yaw even though there is no movement and the quad is on a flat surface. Maybe this is a PID issue??
Configurator is reporting that all accels and gyros are fluctuating between -1 and 1 on the flat surface (with the exception of Z which is ~408) with no throttle and of course a little more fluctuation when the motors are running bc of vibration.
I am using Turnigy 25A Sentry ESCs and the 880kv 2836/9 Outrunners. I do not want to put the props on until its ready to fly. Thanks in advance :)
Thanks for all the support thus far on building my first arducopter.
Yesterday, I had finally completed the frame, uploaded the recent ArdupiratesNG code, calibrated my ESCs, checked motor directions, calibrated the TX through configurator, calibrated accel sensors, etc.
It seemed as if all was ready to go, so I prepared for a pre-flight check with no props and armed the motors. (I have Xbees enabled and relaying data back to configurator wirelessly). Immediately, configurator showed the 4 motors jump from "1040" to "1100" (motors not spinning). This seemed correct as the quad was now armed.
Now heres the trick, As I increased the throttle to say around 20%, at first the Front and Rear motors would increase to about 1200 but then drop down to 1100 and stop running. At the same time, the other 2 motors (Left and Right), would continue to gain power until the reach around 1400.
Now I tried increasing throttle to 50%, and a similar situation occured. This time, the Front and Rear motors reached around 1450 before they started dropping back down to around 1200 (Spinning but Low RPM). The other two motors (Left and Right) continued to gain power until they reached around 1750.
My first reaction was to check trims (which were all 0), and recalibrate, but to no avail. It seems as if the quad is trying to overcompensate for a shift in yaw even though there is no movement and the quad is on a flat surface. Maybe this is a PID issue??
Configurator is reporting that all accels and gyros are fluctuating between -1 and 1 on the flat surface (with the exception of Z which is ~408) with no throttle and of course a little more fluctuation when the motors are running bc of vibration.
I am using Turnigy 25A Sentry ESCs and the 880kv 2836/9 Outrunners. I do not want to put the props on until its ready to fly. Thanks in advance :)
Tags: PID, arducopter, ardupirate, configurator, motors, problem, takeoff, yaw
Replies to This Discussion
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Permalink Reply by charlie Soppelsa on -
Hi
I think I had the same problem with my first flights yesterday. I think it's a PID issue. I found that if I held the copter above my head for a few seconds after throttling up the motors, then throttled back I could take off okay, but it still takes a couple of second to fully stabilise in the air, did not need to move the trims.
Be interested to see what other people say.
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Permalink Reply by Franco Scipioni on -
Thanks for the reply Charlie, glad you could take off eventually!
I hope it's nothing more serious than a PID issue but we'll see.
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Permalink Reply by Sebastian Gralla on -
it's not a PID problem
go to transmitter adjust screen, check if yaw channel is 1500, if not, trim it to get it there
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Permalink Reply by Christopher Williams on -
I saw the same problem when I first started playing with "stable" mode. In acro mode all 4 motors would ramp up at exactly the same rate, however in stable mode, only 2 motors would spin when the copter was sitting on a flat surface. I went ahead and took it out for a flight anyways and it flew just fine. I think it has to do with the copter being motionless and the code decides it doesn't need to run 2 of the motors until needed. May be worth looking into if nothing else mentioned here works.
-Chris
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Permalink Reply by Sebastian Gralla on
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almost... the code wants to turn the copter (because yaw is not centered), but as the copter sits still and not moving, it tries harder -> two motors slow down
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Permalink Reply by Manor A. on
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Had the same issue today.
The configuration is stable mode w magnetometer and no GPS (indoor).
It feels like the heading/yaw gain is too high AND/OR the heading reading has some drift.
I have verified the trims are set to zero and anyhow it was happening to both yaw direction randomly.
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Permalink Reply by Sebastian Gralla on
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it's not an issue at all
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Permalink Reply by Franco Scipioni on
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Thanks for all the responses. I double checked the yaw on the transmitter and verified that it was at 1500. But what you guys are saying sounds logical, the quad is detecting that yaw is not centered so it tries to correct this. But if the issue is not in the transmitter, where could it be coming from? Yaw sensors perhaps?
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Permalink Reply by Christopher Williams on
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Is this only happening while you are holding it in one place or is it happening while flying as well? If you aren't moving the copter at all, I'm pretty sure this behavior is expected. Try taking it outside and see if you can get it off the ground. Mine did the same thing and once it began to move it was fine.
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Permalink Reply by Sebastian Gralla on
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yes, take it into the air
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Permalink Reply by Franco Scipioni on
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You guys gave me a confidence boost so I put the props on and tried away!
First attempt I slowly crept the throttle up and it seemed like what was happening earlier was happening now, the quad was yawing while trying to take off. Finally, it took off but immediatly tried to dive to one spot so I brought throttle down to 0 and reset.
I kept trying to take off but the same thing occured, quad would get off the ground about a foot, while yawing, and eventually tip over to one side.
Not sure if this issue is related to the previous or if this is a completly unrelated one. Configurator is reporting the same conditions, 2 motors increase while 2 decrease.
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Permalink Reply by Christopher Williams on
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How does your copter fly in acro mode? One other thing, have you calibrated your accelerometers using the CLI? I missed that early on and that made a huge improvement.
-Chris
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