[ros-users] Synchronizing computers

Patrick Bouffard bouffard at eecs.berkeley.edu
Mon Apr 19 19:13:06 UTC 2010

I have a setup where my robot is capturing images with an onboard
camera, while its pose is being measured by an external motion capture
system, whose software is running on a different PC. The two machines
talk to each other over a WLAN. I need to have good synchronization of
the timestamps in the camera's images and the poses from the mocap

I plan on using the TF library to do the work of determining which
pose message to pick (or messages to interpolate, perhaps?), but this
assumes that the clocks on the computers are well synchronized. Thus
far, I have one gateway computer on the WLAN with internet access that
keeps its clock up to date with OpenNTP, and the two computers
mentioned above using OpenNTP, with the gateway as their NTP source.
I'm not sure of how to check how well this attempt at synchronization
is working, though.

How have others approached this problem? I have heard that Chrony is a
possible solution and would be interested to hear of any experiences
with it or any other method.


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