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Why is Twist message without timestamp

asked 2012-03-15 21:56:58 -0600

ZdenekM gravatar image

updated 2012-03-15 22:12:16 -0600

Hi,

I'm just wondering - what is the reason for fact, that Twist message has no timestamp?

There is also TwistStamped message type, but as I know it's not commonly used for commanding robots...

Why I'm asking... Because I would like to do some "postprocessing" to data from bag file and because of missing timestamp in cmd_vel topic, I'm not able to precisely compare influence of different commands on robot motion.

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answered 2012-03-15 22:36:40 -0600

this post is marked as community wiki

This post is a wiki. Anyone with karma >75 is welcome to improve it.

The Twist exists separately of the TwistStamped so that you can compose it into larger messages.

If you're logging the cmd_vel topic you do have the time of receipt, which is not quite perfect. However a timestamp on the velocity command does not have inherent meaning. Is it the time the message was sent? When it should be executed? If so what do you do before or after? And on top of all these questions, adding the header significantly increases the bandwidth usage of this high frequency topic.

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Asked: 2012-03-15 21:56:58 -0600

Seen: 688 times

Last updated: Mar 15 '12