IMU specifications and VIO performance documentation on VOXL

Jagatpreet Nir

The VOXL documentation shows two IMUs imu1 (ICM-20948) and imu0 (ICM-42688-P). In the documentation, it is recommended to use imu 1 (ICM-20948) as it gives better VIO performance. https://docs.modalai.com/voxl-flight-datasheet-imus/

However, when I looked at the datasheets of these two IMUS - it is IMU0 (ICM-42688) that has lower gyroscopic and accelerometer noise and should perform better VIO for the same camera. The datasheet links are below

IMU1 datasheet

IMU0 datasheet

Please clarify.

Chad Sweet

Early VOXL Flight (M0019) builds had issues with that IMU due to 2nd reflow required for the POP memory. We have since resolved that so it's likely IMU0 performs as well as better as IMU1.

Future versions of the PCB will move the IMU0 to the other side of the board to remove any issue completely.

James Strawson

Hello,

VOXL and VOXL Flight contain different IMU combinations. on VOXL, IMU1 should be preferred, and on VOXL Flight IMU0 should be preferred.

Configuring MPA services with voxl-configure-mpa will automatically select the correct IMU for the VIO service based on board part number.

I've updated the documentation to clarify: https://docs.modalai.com/voxl-flight-datasheet-imus/

Best Regards,
James

m4v3r

@James-Strawson hello there James.
I've been dumbfounded by the "IMUs" page in your documentation for quite some time now so I'm very thankful that you took that on.^^

Can you please clarify a few things for me here:

1:What do you mean by 'likely DNI'd' for Fligh Ccore IMU3?
Sorry, I actually don't know what that means.

2: For now I'm only using the Flight Core -part of the VOXL-Flight so does that mean PX4 by itself is always only using the 20602 and the 42688p?

3: I've tried using the suggested command "voxl-configure-mpa" in an SSH shell, via ADB and in QGC's nutshell CLI but always get an error "command not found".
Where exactly would I use that? Using other "voxl-" related commands usually work no matter where I enter them so could you please maybe point me in the right direction?

Here's the output when checking for present IMUs:

Thanks a lot for all your guys' work and a nice week to everyone. Cheers.