Gonna get two (you heard that right – two!) Flights in today, and a thought occurred to me: Does the flight controller actively adjust to maintain attitude in manual mode? This would seem necessary, or wind would easily mess up whatever pitch/roll attitude you've set up (think of a dive straight down – might be no stick input at all for a second or two).
Attitude hold in manual?
- Thread starter rktman
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In manual sticks adjust rotation rate around each axis, so with the stick centered the FC actively keeps the current attitude.
Thanks Kilrah... I probably didn't state the question well. I knew that attitude only changed with stick input in manual mode. But I wasn't sure if the flight controller on board the aircraft uses the IMU gyro input to actively hold that attitude i e the pitch angle and roll angle that you have set up.
It would seem critical with such a small aircraft, but I don't know. Experience tells me that that little thing would lose pitch and roll angles almost immediately due to air turbulence if the IMU wasn't holding them.
It's really more of an engineering question, how stability is achieved in manual mode when I'm not giving it in the input.
It would seem critical with such a small aircraft, but I don't know. Experience tells me that that little thing would lose pitch and roll angles almost immediately due to air turbulence if the IMU wasn't holding them.
It's really more of an engineering question, how stability is achieved in manual mode when I'm not giving it in the input.
It's not possible to fly a quad without active stabilisation, so yes it does. As mentioned stick centered -> desired rotation rate around that axis = 0 -> the FC does what it needs for the rotation rate to remain 0, and as such maintains the attitude.
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I figured as much... Kind of like a Heli without a gyro. Try to fly an RC Heli straight without a gyro chuckle chuckle chuckle
droneguy
Well-Known Member
There is no altitude hold in manual. The combination of your throttle position relative to your pitch/roll axis determines if the thrust is sufficient or not to maintain altitude. The IMU provides data on the acceleration and angular velocities (and magnetic field if magnetometer is present). Your stick inputs cause the FC to send commands to all the motors to slow or speed up in order to follow your stick inputs. The PID controller (loops at high frequency) and corrects the error or difference between your set-point and measured value (from the gyro sensor data). There is no process in manual mode that corrects any set-point to maintain altitude as there is no set-point for altitude.
As a pilot, you need to match the necessary throttle position to maintain altitude depending on your angular pitch/roll. Any time you add or remove pitch/roll, you need to readjust the throttle to maintain altitude otherwise you will drop or raise in altitude. This is the challenge and the precision that is manual mode.
droneguy
Well-Known Member
This is not exactly true. The PID controller's job is to use the gyro and accelerometer data to match the set-points you as a pilot input with your sticks. If you are trying to hover in manual mode, as a pilot, you will try to perfectly level you quad (which is almost impossible). Let's say you you're pretty awesome and you end up with forward pitch to 1 degree and roll right to one degree then center your sticks. This is your set-point. if your sticks aren't moving, then your set-point isn't changing. The PID controller will compensate for any deviation (wind, turbulent air etc) and try to keep you at this set-point 1 degree forward and 1 degree roll. If you want to maintain altitude, your throttle position needs to be set manually at the point that the thrust generated by the props equals the opposing forces of gravity. There is no altitude compensation. As you add angular pitch/roll like when you are flying forward quickly for instance, once your set the angle and re-center recenter your pitch/roll sticks your set-points are effectively not changing again because your sticks aren't moving. The thrust required to maintain a constant altitude is greater since not all the thrust is vectored downwards. You need to manually adjust your throttle position to the precise spot where again, you match the downward thrust with the effects of gravity. This is why in manual mode you, throttle control is the most important skill to develop.
The PID controller's job in this case is to hold the exact angle you set as your set-point. Your PID loop affects the throttle to adjust the motors when you have a set-point that isn't being met fast enough or not tracking (this happens thousands of times per second). Every time you move your sticks, the PID controller is working to keep the quad perfectly synchronized with your set-points. This is where the term locked-in comes from. When you have a drone that is very well tuned, the PID controller will do an exceptional job at tracking (following) your set points with very little delay and with no overshoot (over compensation which shows up in the form of oscillations). So technically the PID controller adjusts the motor speed, but not in order to maintain altitude, but only to track to your set-points. Altitude is 100% on the pilot to control with precise throttle control.
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This is also why so many of the youtube posted accidents happened because the Pilot forgot to Throttle up when Looping or Flipping and end up in the Ground in a blink of an eye. Throttle control has to be the Focus as this also explains why so many FPV flyers downplay the Throttle on the DJI as being a little weak, which makes total sense now as having never flown FPV before I would not be aware of a weak throttle.
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Gear to fly FPV in the rain coming Soon.
Yes of course.
It holds every attitude you are in if the sticks are centered. Even upside down.
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I have yet to see any footage of it holding upside down, for how long can you fly it like that ?
About as long as gravity will take to bring you back down from whatever height you're at plus your current vertical speed in freefall, minus a bit for idle thrust, plus a bit for aerodynamic drag 
Sigh... the beauty of variable pitch blades on an RC Heli... could produce as much upward thrust as down.About as long as gravity will take to bring you back down from whatever height you're at plus your current vertical speed in freefall, minus a bit for idle thrust, plus a bit for aerodynamic drag
While I was able to get in a few successful rolls and loops, my helicopter days were pretty short. Just way too too too too expensive to repair, and I didn't have the income 15 years ago that I do now.
After around the 10th crash, I couldn't afford to fix it again, and was frustrated as a blind man with the furniture rearranged.
Eventually fixed them (2) with the intent to give it another go, but never got the nerve.
Nice ornaments on a bookshelf
I was never very good at 3D, but I could hover upside down for a short time and do loops and rolls. Never tried to cut grass like a lot of people do. Definitely had my share of expensive repairs.Sigh... the beauty of variable pitch blades on an RC Heli... could produce as much upward thrust as down.
While I was able to get in a few successful rolls and loops, my helicopter days were pretty short. Just way too too too too expensive to repair, and I didn't have the income 15 years ago that I do now.
After around the 10th crash, I couldn't afford to fix it again, and was frustrated as a blind man with the furniture rearranged.
Eventually fixed them (2) with the intent to give it another go, but never got the nerve.
Nice ornaments on a bookshelf
Sadly, mine too are now ornaments on a shelf. I keep thinking I'll get them back in the air someday. Though I'd probably want to put a new receiver in them, since they are old enough that they used 72MHz FM radios.
EDIT: By the way, Curtis Youngblood made and collective-pitch 3D quad called the Stingray. That thing was crazy maneuverable!
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I started with RC gliders, the Gentle Lady. Man, that was an incredible bird to soar with along Pacific Ocean cliffs. Could stay up as long as I wanted, and made the most beautiful loops.
Anyway, I had my eye on helicopters because the machinery fascinated me. The mechanical linkages, how they work, etc., was so fun to build. I got good enough to fly around pretty well, and like I said, I was able to learn to loop and roll, at great cost ?
A pitch adjustable quad is 4x the linkages -- man, gotta be someone for which "money is no object" to acro that beast!!
Anyway, I had my eye on helicopters because the machinery fascinated me. The mechanical linkages, how they work, etc., was so fun to build. I got good enough to fly around pretty well, and like I said, I was able to learn to loop and roll, at great cost ?
A pitch adjustable quad is 4x the linkages -- man, gotta be someone for which "money is no object" to acro that beast!!
