I don't have a good answer for maintaining the clocks, but if you want to
check the offset, you can use the `ntp_monitor.py` node in
`pr2_computer_monitor`. Full docs are on the wiki.

Kevin

http://www.ros.org/wiki/pr2_computer_monitor#ntp_monitor.py


On Mon, Apr 19, 2010 at 12:13 PM, Patrick Bouffard <
bouffard@eecs.berkeley.edu> wrote:

> 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
> system.
>
> 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.
>
> Thanks,
> Pat
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