First time posting here after reading quite a bit of your posts here.
We’re a student team from Stockholm who are building a UAV controlled by the PixHawk 4 and have stumbled upon some problems with the different flight modes. Here’s what we’re working with.
- Bicopter configuration with motor mounts capable of tilting in roughly ± 90 deg
- Flight modes set to 1. Fly By Wire B, 2. QHover, 3. Manual
- Q_enable set to 1
- Q_frameclass set to 10
- Q_tiltmask set to 3
- Q_tilttype set to 2
Images of the thing.
The behavior we want:
- Start on ground in QHover, the tilt motors tilt upwards, away from the ground, and we throttle up. The plane gains altitude and behaves as a bicopter.
- After the initial take off, we start to accelerate and switch the flight mode to Fly By Wire B where the plane transitions into horizontal flight. When this mode is selected the plane rotates its motors to a forward facing configuration after the correct airspeed and angle is achieved.
- For landing the planes airspeed is lowered to where the angle of the wing body is high and it is flying close to stall speed. Here we switch back to QHover to land vertically.
Pretty basic! We’ve achieved this stable behavior before with exactly the same parameter as are currently on the Px4. But, before our first test flight of the take off procedure we simple couldn’t get it to behave as before. Instead we got this behavior:
- The plane tilts it’s motors upwards when in QHover as before but now they move from +90 to -90 degrees extremely fast. They seem to react strongly to yaw input.
- In both Fly By Wire B and Manual the motors tilt down towards the ground (-90 deg) and stay there no matter the orientation of the plane.
Any ideas and or tips are greatly appreciated.