Repeated IMU Timestamp

[KitKat7]

Required Info
Camera Model	D435i
Firmware Version	05.11.01.100
Operating System & Version	Linux (Ubuntu 18.04)
Kernel Version (Linux Only)	4.15.0-47-generic
Platform	PC
SDK Version	2.19.2
Language	N/A
Segment	Robot

Issue Description

I was trying to collect some data from D435i, with both images and IMU data.
But I found the timestamps of IMU data in the collected bag were incorrect (repeated). A figure with acceleration timestamps plotted is shown below. Similar problem existed for gyroscope data.

I tried the realsense-viewer and the ROS wrapper to collect the data. But both provided the same results. I guess the problem might be from librealsense. I'd appreciate any help :).

[dorodnic]

Do you know if you are running on a patched kernel?

[KitKat7]

Hi @dorodnic thanks for your reply. I'm not sure how to check whether I'm running on a patched kernel, but I didn't manually do kernel patching.
The results from cat /etc/os-release is shown as following:

NAME="Ubuntu"
VERSION="18.04.2 LTS (Bionic Beaver)"
ID=ubuntu
ID_LIKE=debian
PRETTY_NAME="Ubuntu 18.04.2 LTS"
VERSION_ID="18.04"
HOME_URL="https://www.ubuntu.com/"
SUPPORT_URL="https://help.ubuntu.com/"
BUG_REPORT_URL="https://bugs.launchpad.net/ubuntu/"
PRIVACY_POLICY_URL="https://www.ubuntu.com/legal/terms-and-policies/privacy-policy"
VERSION_CODENAME=bionic
UBUNTU_CODENAME=bionic

I tried previous SDK with version 2.19.1 as suggested in IntelRealSense/realsense-ros#703. This problem seems not appeared.

[ev-mp]

@KitKat7, thanks for the report.
We confirm that IMU 3-second wraparound is a bug in V2.19.2 and will be fixed in the next release.

[ev-mp]

The fix is available in v2.21.0 release

[KitKat7]

@ev-mp, this bug disappeared in v2.21.0. Thanks for the fix :).