I have a powerful quad and I have a major problem in tuning the altitude controller. Due to the high thrust to weight ratio, the MOT_HOER_LEARN parameter is unable to calculate the MOT_THST_HOVER value correctly. I set the MOT_THST_HOVER value from CTUN>>ThO and used it to set the MOT_THST_HOVER values and the PSC_ACCZ_P, PSC_ACCZ_I values, but with this setting the quad was unable to maintain altitude. Then I manually selected a higher value for these parameters (0.1 for MOT_THST_HOVER) but there were a lot of fluctuations in altitude. I also significantly reduced the PSC_VELZ_P and PSC_POSZ_P values, but the altitude controller is still not good. what should I do?
The problem is that due to the high thrust-to-weight ratio, setting MOT_HOVER_LEARN=2 sets the MOT_THST_HOVER value to its minimum value of 0.125, which does not seem to be the correct number according to the log. According to the posts I saw from other people, they also mentioned this issue.
I am not sure, but if you have set it to 1, and the system does not allow for the thrust value go below 0.125 then possibly you should disable learning completely, i.e. set it to 0, and manually try out hover thrust values.
I don’t know where to start with my settings. Should I start with the current values and adjust them, or should I reset everything to the defaults and start over?
Also, should I adjust the MOT_THST_HOVER value first, or the altitude controller values? Finally, when tuning the altitude controller, should I tune the acceleration values (PSC_ACCZ_P and PSC_ACCZ_I) first, or is the issue actually rooted in the velocity and position values (PSC_VELZ_P and PSC_POSZ_P)
In previous flights, looking at the flight logs and the CTUN.ThO value, the average hover thrust appeared to be 0.07, so I set MOT_THST_HOVER to this value. Based on that, I set PSC_ACCZ_P to 0.07 and PSC_ACCZ_I to 0.14, while leaving PSC_VELZ_P and PSC_POSZ_P at their default values. However, when I switched to ALT_HOLD mode, the drone suddenly dropped toward the ground. I immediately switched back to STABILIZE mode, but it was a bit late, and the drone hit the ground and bounced back into the air.
The parameter MOT_HOVER_LEARN was set to 1. Could the cause of this drop be that this parameter wasn’t set to 0, or is it possible that the ThO value was reported incorrectly in the log?
I think I should set a higher MOT_THST_HOVER value, something like 0.08.
As @LupusTheCanine suggested the log is full of EKF errors. When it dropped to the ground the Optical Flow quality went to hell. I don’t know if it’s related or not. Choose a better Flight Controller.
