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Very large delay in ROS image topic between machines in wlan

asked 2021-08-18 13:20:47 -0500

I'm working with a scaled model car which has a realsense SR300 camera, this is the car: It has an odroid XU4 with Ubuntu 16.04 running ROS kinetic.

The car sends the camera image to a ROS topic by a realsense nodelet. The ROS_MASTER is in a laptop, also with Ubuntu 16.04 running ROS kinetic, in a wlan in which the car is too. The problem is that there are tons of delay in the topic that publishes the camera images:

:~$ > rostopic delay /app/camera/rgb/image_raw/compressed
subscribed to [/app/camera/rgb/image_raw/compressed]
average delay: 1359.301
         min: 1358.945s max: 1359.655s std dev: 0.23105s window: 9

And the delay grows and grows even more. This is the ping from the laptop to the car:

:~$ > ping
PING ( 56(84) bytes of data.
64 bytes from icmp_seq=1 ttl=64 time=2.44 ms
64 bytes from icmp_seq=2 ttl=64 time=2.45 ms
64 bytes from icmp_seq=3 ttl=64 time=1.98 ms

This is the bandwidth consumption of the topic:

:~& > rostopic bw /app/camera/rgb/image_color/compressed
subscribed to [/app/camera/rgb/image_color/compressed]
average: 365.30KB/s
       mean: 35.36KB min: 35.29KB max: 35.43KB window: 8

The clock time of the machines is sync with ntp. The delay is similar for the non-compressed image topics. The camera was initially taking images at 30Hz, then I set it at 10Hz but the problem persists. It is worth to mention that the delay is almost zero at starting the realsense nodelet, but it grows along the time.

I would really appreciate if you can tell me what I'm missing. Thanks in advance, kind regards.

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answered 2021-08-27 12:09:45 -0500

Just in case that anybody else has the same problem, I solved it by reinstalling the realsense_camera package. In my case, this package was in a catkin workspace folder, I removed it from there and then I installed it by:

sudo apt install ros-kinetic-realsense-camera
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Asked: 2021-08-18 13:20:47 -0500

Seen: 16 times

Last updated: Aug 27