Hello, I am using an OAK-D Pro W PoE camera and have noticed a drift of 2m/s^2 in the linear acceleration in the x-direction. I have used the imu_extrinsics_update.py file from depthai-calibration (https://github.com/luxonis/depthai-calibration/blob/main/imu_extrinsics_update.py) to update my IMU, however my offset has not changed. is there any calibration files i can run to fix this error? any help is appreciated, thanks!

Hey @"dr_king_crawford"#p33858 - yes in `depthai-ros` this is controlled by ROS parameters, not directly in `imu.cpp`. The files to look at are: [imu_param_handler.cpp](https://github.com/luxonis/depthai-ros/blob/kilted/depthai_ros_driver/src/param_handlers/imu_param_handler.cpp) [config YAML](https://github.com/luxonis/depthai-ros/blob/kilted/depthai_ros_driver/config/vio.yaml) The params you want are `i_acc_mode` and `i_gyro_mode` under the `imu:` section. For your case, try `i_acc_mode: ACCELEROMETER` rather than `LINEAR_ACCELERATION`. The key params are: - `i_acc_mode` - `i_gyro_mode` For your case, try setting: - `i_acc_mode: ACCELEROMETER` - not `LINEAR_ACCELERATION` You’ll usually set that in your launch YAML under the `imu:` section. Best, Oskar

OAK-D Pro W PoE camera x-axis linear acceleration drift

dr_king_crawford

Hello, I am using an OAK-D Pro W PoE camera and have noticed a drift of 2m/s² in the linear acceleration in the x-direction. I have used the imu_extrinsics_update.py file from depthai-calibration (luxonis/depthai-calibrationblob/main/imu_extrinsics_update.py) to update my IMU, however my offset has not changed. is there any calibration files i can run to fix this error? any help is appreciated, thanks!

OskarSonc

Hey dr_king_crawford - imu_extrinsics_update.py only updates the IMU-to-camera extrinsics, so it won’t fix a steady accel bias or LINEAR_ACCELERATION offset by itself.

The first thing I’d check is which IMU stream you’re using. If it’s LINEAR_ACCELERATION, avoid that one for now and test with ACCELEROMETER_CALIBRATED instead. Recent DepthAI builds added separate RAW / UNCALIBRATED / CALIBRATED IMU outputs, but LINEAR_ACCELERATION is known to be problematic, so a 2 m/s² residual there would not be surprising.

So the practical next step is:

keep the camera completely still
log ACCELEROMETER_CALIBRATED and GYROSCOPE_CALIBRATED
check whether accel magnitude is near 9.81 m/s² and gyro is near 0

Best,
Oskar

dr_king_crawford

Hi Oskar,

Thanks a lot for your reply! It is really helpful to know that there are multiple IMU streams. Could you direct me to the node/launch file wherein I can change the IMU stream? I currently have depthai-core and depthai-ros added into my humble workspace and am looking through depthai-ros > depthai _ros_driver > src > dai nodes > sensors > imu.cpp and I cannot find a method to change the stream.

Thanks for your help!

OskarSonc

Hey dr_king_crawford - yes in depthai-ros this is controlled by ROS parameters, not directly in imu.cpp.

The files to look at are:
imu_param_handler.cpp
config YAML

The params you want are i_acc_mode and i_gyro_mode under the imu: section. For your case, try i_acc_mode: ACCELEROMETER rather than LINEAR_ACCELERATION.

The key params are:

i_acc_mode
i_gyro_mode

For your case, try setting:

i_acc_mode: ACCELEROMETER
not LINEAR_ACCELERATION

You’ll usually set that in your launch YAML under the imu: section.

Best,
Oskar

dr_king_crawford

Hi Oskar,

Thanks for your help. I am using version humble-v3 of depthai-ros and have updated vio.yaml as well as the imu param handler node, however after building the package the offset is still present. I've attached a screenshot of our values if this makes my situation clearer. Thanks again for your help, let me know if there is anything else I can mention which could help!

OskarSonc

dr_king_crawford - the screenshot is actually helpful. One important detail is that in ROS the field is always printed as linear_acceleration, even if the underlying DepthAI stream is just the normal accelerometer. So that label by itself does not confirm you are still using the LINEAR_ACCELERATION mode.

In humble-v3, the actual stream is controlled by i_acc_mode, and if it is not explicitly overridden it defaults to ACCELEROMETER_UNCALIBRATED. So the next thing I’d check is whether your edited vio.yaml is actually the file being loaded at launch. Also check that you are on the latest Humble v3 release v3.2.1-humble.

Best,
Oskar