Hello everyone ,
Today i start to test the hff filter on my quadrotor. First of all i observe the acceleration inputs for the filter ('b2_hff_xdd_meas' and 'b2_hff_ydd_meas'). The output is 'xdd.jpg' at the attachment(don't care about the label of the data, this is 'b2_hff_xdd_meas'). Here i want to mention the local tangent plane approximation works good. This log is holded while the rotorcraft flying, I believe the main source of noise on this output is the vibration. Secondly i observe there is some noisy effects while the multirotor changes its orientation, due to some errors and delays on Ahrs side, but this effect is little then i expected. In conclusion the real horizontal accelerations can be seperated from the noisy output and i have decided that this acceleration input may be useful with some little healings.
Here i have two options on my mind, what is your opinion?
1) The source for 'b2_hff_xdd_meas' is derived by taking LTP of 'acc_body_mean' which is the arithmetic mean value of the latest 16 acc. values coming from imu. Maybe more sharpener (IIR may be useful) filter with smaller phase delay (4-5 order etc) can be used rather than mean value of 16 inputs?
2) A filter on 'b2_hff_xdd_meas' directly before the input of Hff filter may be useful. I am not sure about this idea, it may cause the loss the meaningful data of horizontal acceleration.
Anyway with this point, i have decided to move a step forward without any modification in the source code. Afternoon, i will try to make deeper tests with position and speed estimates. By the way, i make settings on Hff as;