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I'm wondering what timestamp in hokuyo's sensor_msgs::LaserScan does mean. Is the time at first scan ray is measured? Or is the time at last scan ray is measured?
I know there is calibration function of latency between hokuyo and host PC in hokuyo node. But I cannot understand how the function works. Could you explain to me? Thanks in advance.
The timestamp is the the time of the first ray/distance measurement in a scan. Note this is also stated in the comments of the sensors_msgs/LaserScan message definition.
The time calibration performs some sending of messages back and forth between scanner and host similar to NTP time synchronization. There is some more info here on page 27 of the UTM-30LX-EW protocol documentation.
Yes, the driver node should take care of publishing the proper ROS timestamp for the message, based on the preceding time calibration. For details you have to look at the code.
Don't know, you'll have to look at the code. But just taking ros::Time::now() is an approach that's commonly taken if no complicated sync as with the hokuyo is done.
Asked: 2016-01-12 04:53:03 -0500
Seen: 850 times
Last updated: Jan 12 '16
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