Bitcraze Forums

Hi
Fly Crazyflie at height lower than 10 cm is sometimes difficult. It is known in aircraft theory that ground can induce specific effects for low altitude flights. It is the "ground effect".
For Crazyflie, low altitude means roughly 10 cm. You can have sometimes the feeling that cf is just like a wet soap in your hand.
I must say for these tests that my PLS25H sensor is not active (it is broken and firmware inhibited).
I experimented this flight with two configurations.
For the first one, it is the standard no deck configuration. Then firmware uses standard estimator. Flight is stable, only the "soap" effect can occur.
For the second one, I add the flow-deck. When flying under 10 cm, large roll and pitch dangerous continuous oscillations can appear, which is not the case in the first configuration.
To go on with this behaviour, my questions are:
1/ is it possible to use flow-deck with standard estimator, and how?
2/ how use no-deck configuration with Kalmann filter for sensors (estimator 2)?
Thanks in advance.
BR
Jean-Claude

1) When flying close tho the ground it will be harder for the flow sensor to track the surface since it is moving faster. Also shading and light condition might come into effect. Currently we have not implemented any support for the complementary filter (estimator 1).
2) You can force the use of the kalman filter by putting "ESTIMATOR=KALMAN" in the config.mk file.

Thanks, I proceed...