@Chad-Sweet actually what I meant was when I moved the aircraft purely in the X direction, the Z estimates decreases.

Sorry if I wasn't clear

Switching between imu0 and imu1 in voxl-qvio-server.conf does not seem to have any effect.

And just so that i'm sure that i've configured the extrinsics correctly; assuming that the new position and orientation of the tracking camera is as follows (and at same Z-height as the IMU):

Would the relationship be:

                    "parent":       "imu1",
                    "child":        "tracking",
                    "T_child_wrt_parent":   [a, -b, 0],
                    "RPY_parent_to_child":  [0, 90, 90]

Hi devs,

Im stumped and really need help.
I've shifted all the hardware from a Seeker into my own airframe, and have done the following:
-configured the extrinsics
-re-calibrated IMU
-re-calibrated tracking camera
-the new airframe flies well in Manual/Stabilized mode

I have yet to switch to Position mode because - while on the ground (motors not spinning; no vibration etc), when i move the aircraft in the positive x-direction (reference frame where the VIO initializes - pointing fwd towards the nose of the aircraft), the z-position estimate decreases (ie it thinks it is gaining altitude).

The same phenomenon happens regardless of the aircraft's orientation/heading as long as i move towards the x-direction. The Z position estimate moves by -0.3m for approximately 5m moved in X direction. X and Y positions are estimated correctly

As i move back towards the starting pt (negative x-direction), the change in z-position estimate reverses and it goes back to 0 (almost) at the starting point. Again, this is regardless of the aircraft orientation.

Im stuck... help needed and appreciated.

Thanks

@Alex-Kushleyev

When using RPM control, the mapping between thrust and RPM is usually an almost perfect quadratic, so you should probably use THR_MDL_FAC = 1 to make it quadratic. However, let me double check that last point.. The value of this parameter should not change when you change motor / propeller, since thrust is almost always a pure quadratic vs rpm.

Hi @Alex-Kushleyev , did you manage to find out if THR_MDL_FAC should be set to 1 or should i calibrate the thrust curve?

PX4's docs specified in https://docs.px4.io/v1.12/en/config_mc/pid_tuning_guide_multicopter_basic.html that if the ESC is a RPM-controlled one, no tuning is required:
For PWM controllers, 0.3 is a good default (which may benefit from further tuning).
For RPM-based controllers, use 1 (no further tuning is required as these have a quadratic thrust curve).

But i noticed from ModalAI's reference params (eg Seeker's https://gitlab.com/voxl-public/flight-core-px4/px4-parameters/-/blob/master/platforms/v1.12/Seeker/Seeker_v1_param_rev_A.params) that the you guys did a calibration regardless

# Dyno test shows this model should be 0.90
1	1	THR_MDL_FAC	0.90	9

Hi devs

Referring to the following statement from Seeker's and Sentinel's docs and with EFK2_AID_MASK == 280, EKF2_HGT_MODE == 3,

If VIO data is not being transmitted, the system will fall back to altitude mode and you will hear “position mode rejected, altitude flight mode”.

I understand that when VIO fails, the 2D x-y position hold obviously fails, but how about the altitude holding capability in Altitude Mode? Does it also go out of the window or does it somehow revert back to fusion of barometric pressure sensor and z-accelerometer?

@Chad-Sweet does that apply to the hires as well or just the tracking?
My brand new hires seems abit blurry..

@Sam-Armstrong awesome!