IMU/Gyro Calibration

[Andrew Jue]

I'm using a VOXL2 (m0054) running SDK 1.6.5 in a custom airframe, and I wanted to confirm somethings about the calibration process. In the past, I thought I was able to use voxl-calibrate-imu to calibrate the IMU and gyros in lieu of running the calibration through PX4. However, recently that doesn't seem to work anymore.

Based on what I've been able to find on the forum, the IMU used by PX4 is separate from the IMU used by ModalAI apps and isn't calibrated by voxl-calibrate-imu. Can you confirm that in order to prepare a vehicle for flight, I'd need to calibrate the imu_apps IMU using voxl-calibrate-imu and then also calibrate the PX4 IMU through QGC (and ignore the pop-up about unreliable calibration over WiFi)?

Also, for other VOXL IMU related commands like voxl-inspect-imu and voxl-calibrate-imu-temp, are these only for imu_apps (i.e. not for the PX4 imu), or is there a way to get these to show information from the PX4 IMU?

[Eric Katzfey]

Yes, your understanding is correct. To see the PX4 IMU values use standard PX4 commands. For example, on voxl2 you can use the PX4 listener commands:

voxl2:/$ px4-listener sensor_accel 

TOPIC: sensor_accel
 sensor_accel
    timestamp: 30123125 (0.006725 seconds ago)
    timestamp_sample: 30122829 (296 us before timestamp)
    device_id: 2490378 (Type: 0x26, SPI:1 (0x00))
    x: -0.05360
    y: 0.01754
    z: -9.68999
    temperature: 34.62560
    error_count: 0
    clip_counter: [0, 0, 0]
    samples: 20

voxl2:/$ px4-listener sensor_gyro 

TOPIC: sensor_gyro
 sensor_gyro
    timestamp: 37716660 (0.003955 seconds ago)
    timestamp_sample: 37716405 (255 us before timestamp)
    device_id: 2490378 (Type: 0x26, SPI:1 (0x00))
    x: -0.00409
    y: 0.00796
    z: -0.01429
    temperature: 34.32669
    error_count: 0
    clip_counter: [0, 0, 0]
    samples: 20