Realsense-ros: d435i accel and gyro have really diffrent time stamp

[Dunkem]

when I use the d435i for vio application, but the time stamp is really untrusted between accel and gyro.
the gyro time stamp is below:
header:
seq: 425
stamp:
secs: 3101275587
nsecs: 883002758
frame_id: "camera_gyro_frame"
while the accel tiem stamp is:
header:
seq: 424
stamp:
secs: 1550637828
nsecs: 963475704
frame_id: "camera_accel_frame"
could anyone tell me why cause this huge time differences between accel and gyro

[Shashika007]

@Dunkem They are totally independent and also not synchronized. I'm testing D435i for VIO also. I saw the discontinuity after select the unite_imu_method as linear_interpolation (https://github.com/intel-ros/realsense/issues/577). I think the topics are not published with the same timestamp. I'm using the latest firmware and ros wrapper. But, still they have not fixed the problem i guess.

[Dunkem]

@Shashika007 I know this two sensor is not synchronized. but actually the time stamp's secs should be the same or just a little difference, but the gyro time stamp's secs seems twice accel time stamp's secs.

[RigerLee]

I'm not sure if setting "initial_reset" in your launch file to true works.
But I've ever encountered such problem between IMU and color image and solved it this way.

[Shashika007]

@RigerLee I already set the initial_reset, I did not noticed any difference.
@Dunkem have you noticed this ? the gyro and accel do not publish the topics continuously with same time delay. Like there are some big gaps between two readings.


@RigerLee @Dunkem Do you guys have any idea about this issue ?

[Dunkem]

@RigerLee I also already set the initial_reset=true,but it seems not work.
@Shashika007 I don't know why cause this big gaps.And can you tell me how do you get this image.

[Shashika007]

@Dunkem you can record a bag file that includes imu data and check it using rqt.

[doronhi]

Hi @Dunkem
The gyro and accel topic are not synchronized but the both have the same clock therefor their timestamps should be very close.
Your gyro timestamp seems almost exactly twice the accel timestamp.
What firmware do you have? librealsense version? realsense2_wrapper version?
What machine do you run it on?
Can you reproduce this phenomena?

[Dunkem]

@doronhi Thank you for your reply！My tun it in my laptop Latitude 7380，the librealsense version is 2.18.1，and I clone the ros wrapp from https://github.com/intel-ros/realsense just 6 days ago.I don’t know what the firmware version is.

[Dunkem]

@doronhi and the gyro timestamp is twice of the accel timestamp whenever I run it

[Shashika007]

@Dunkem you can check your firmware version by intel-realsense-dfu –p (if you don't have dfu install by sudo apt-get install intel-realsense-dfu*). Also, you can update new firmware by following below mentioned guide,
https://www.intel.com/content/dam/support/us/en/documents/emerging-technologies/intel-realsense-technology/Linux-RealSense-D400-DFU-Guide.pdf

[Dunkem]

@Shashika007 Very thanks for your guiding,and my firmware version is 5.10.13.0 @doronhi

[doronhi]

@Dunkem
Can you copy here the command you use to start the realsense2_camera node? what launch file and additional parameters?
What command do you type to print the results you get?

[Dunkem]

@doronhi I run it with command “roslaunch realsense2_camera rs_camera.launch” and I set the parameter "enable_sync=true","unite_imu_method=copy"

[RealSenseCustomerSupport]

[Please Ignore - RealSense system comment]

[bednarhonza]

Hi,
I have the same problem as @Dunkem has. Have you already fixed the issue, or is it still pending?
My firmware version is 5.11.1.100

Thank you,
Jan

[Dunkem]

@Jwenda I sorry but this problem still exist in my device but I replace my computer with jetson tx2 this problem disappear, I don't know why. And because the gap between two readings vio doesn't work well.

[bednarhonza]

@Dunkem Hmm.. interesting. We were running on Intel NUC which doesn't work, but the normal PC works. I will have to do some modification because I have to run on Intel NUC due to our hardware. If anybody finds the reason, please let me know.

Thanks,
Jan

[bednarhonza]

@Dunkem I managed to get rid of different timestamp by compiling the librealsense by myself, but it was on Lenovo PC with dual boot. But now I face another issue, with cycled timestamp, I will have to create a new issue.

[doronhi]

@Jwenda , check out issue 703 about repeating time stamps.

[bednarhonza]

@doronhi Yes, thank you. I have already found it while creating a new issue. Glad it has been solved.

[Dunkem]

it also works on my computer， Thank you @Jwenda

[bednarhonza]

@doronhi @Dunkem I have to correct my answer. I also had to run my Ubuntu on lower kernel version(4.15.0.47) instead of (4.18.0.20) to have a correct timestamp. I know that Intel Realsense SDK does not support the higher kernel than 4.16., so it might be the issue also.