After your first manual controlled flight, you will feel more confident about using the module. This is needed because (for most users) configuring the stabilization will be done in several iterations.
Calibrating the sensors
Calibrating the sensors is easy with the configuration tool:
- Read the settings by clicking the "Read button"
- Make sure your module is flying flat on the table (and make sure your table is perfectly horizontal)
- Click the "Use current" button for the accelerometer part
- Click the "Use current" button for the gyroscope part
In the perfect situation, the Processed value for the accelerometer will be 0g, 0g, -1g for the respective X, Y and Z-axis. The total "g" should always be "1".
When motionless, the gyroscope's processed outputs should be around 0°/s for all axis.
If you want your sensor calibration more perfect, connect the power source you'll use during flight to the module. Before connecting the FTDI cable, you should take the red wired out of the connector. You need to avoid having 2 power sources! (remark: in the modules with a serial number > 10, this will have only a marginal improvement)
The result of the attitude filter can be checked in the "3D cube window" or in the "Dashboard" tab. The graph window can also be used if you are more interested in numbers.
Configuring PID values
The PID-values determine how much the control surfaces should deflect in a certain case. This has to be done for
- Input: Pitch error, output: elevator deflection
- Input: Roll error, output: aileron deflection
- Input: Heading error, output: aileron deflection
- Input: Altitude error, output: pitch angle
In a standard configuration, only the P-values need to be configured. You can leave the others "0".
In the PID-screen, make sure every "P" term has a value of 0.3. The "I" and "D" terms can be "0" for the first flights. Write & Burn to the module.
In the "Control" tab page, you need to program the maximum Pitch and Roll angle. Start with small and safe values. I propose 15 degrees max for pitch, and 35 degrees max for roll. Write & Burn.
Now switch to stabilized mode using your RC-transmitter, and verify that the ailerons, evelons or elevator move to the correct side when you pitch or roll the plane. Is the amount of deflection too small or too big? Then you can change the "P" term of the PID values. It's better to start with a small deflection, people usually make the deflections too big for the first flights. A smaller value = a more gentle flight!
More information about the PID values can be found on the Stabilization PID-loops page.
Now it's time to fly and test the stabilized mode. Keep in mind that several flights will be needed to configure the optimal P-values.
First of all, make sure that the plane flies nice and straight in manual mode (this should be the case if you trimmed it during your first manual flight).
- Power your transmitter, make sure the gas is off and autopilot-mode is manual.
- Power the module and your plane.
- Wait for a GPS lock (LED2 will flash).
- Do a range test.
- Move the stick and verify that manual mode works as expected.
- Go to stabilized mode and verify that the control surfaces move as expected.
- Go back to manual mode for the launch.
Now, launch the plane and fly to a safe(!) altitude. Try not to make any aggressive maneuvers that could saturate the sensors. Fly it gentle. When the plane is flying straight and flat in manual mode, it's time to switch to stabilized mode! When you don't move the sticks, the plane should fly straight. Moving your aileron stick completely to the left or right should give the plane a roll angle of about 35 degrees.
When the plane is oscillating around the roll axis: make the "P" term smaller (half the size). When the plane is not rolling fast enough: make the "P" term bigger (twice the size). The same counts for the pitch axis.