Jan, Based on your topic name it looks like you are using a Sick LMS. There is a ROS driver for it in the sicktoolbox_wrapper which you might find useful to either use or for a reference. It is documented at http://www.ros.org/wiki/sicktoolbox_wrapper Tully On Tue, May 25, 2010 at 3:31 PM, Josh Faust wrote: > Hi Jan, > > It looks like the time_increment field in your laser scans are set to > 0.0924214... this field is meant to be the amount of time between each > reading in the scan, so 90 milliseconds is quite high. rviz multiplies this > by the number of readings in the scan to set the time tolerance on the > filter it uses, to ensure that the entire message can be transformed > correctly, not just the first reading. > > A more reasonable time_increment would be a few orders of magnitude > smaller. An example from our tilting laser is 1.73611115315e-05 > > I've filed a ticket to make rviz warn in cases of unreasonably large > time_increment values: https://code.ros.org/trac/ros-pkg/ticket/4123 > > Josh > > > On Tue, May 25, 2010 at 1:45 AM, Jan Elseberg < > j.elseberg@jacobs-university.de> wrote: > >> Hi, >> >> I uploaded a short bag.file of the robot. You can get it under >> http://plum.eecs.jacobs-university.de/exchange/volksbot.bag . There's >> also >> http://plum.eecs.jacobs-university.de/exchange/only_laser.bag where only >> the laser topic (/volksbotRT/LMS) and /tf is recorded. If you need >> anything else, please let me know. >> >> Jan. >> >> Josh Faust wrote: >> > Can you post a bag file with /tf and the laser scan topic somewhere? >> > >> > Josh >> > >> > On Fri, May 21, 2010 at 5:21 AM, Jan Elseberg >> > > > > wrote: >> > >> > Wim, >> > >> > I have played around with the timestamps of the laser scan message. >> > Neither increasing nor decreasing >> > the timestamp changes the behaviour, except that for large enough >> > offsets either of the following errors >> > is produced: >> > >> > For frame [/front_laser]: No transform to fixed frame >> > [/base_link]. TF >> > error: [You requested a transform that >> > is 2.637 miliseconds in the past, but the most recent transform in >> the >> > tf buffer is 8.092 miliseconds old.] >> > >> > For frame [/front_laser]: No transform to fixed frame >> > [/base_link]. TF >> > error: [You requested a transform that >> > is 3.212 seconds in the past, but the tf buffer only has a history >> of >> > 3.138 seconds.] >> > >> > I have also changed the publishing frequency of the laser scan >> > messages >> > to 5 Hz. Unfortunately, this also had >> > no effect on the error. >> > >> > Jan >> > >> > >> > Wim Meeussen wrote: >> > > Jan, >> > > >> > > When rviz receives laser scan messages, it only keeps the 10 most >> > > recent messages in a buffer. So, if you send laserscans at 50 Hz >> (it >> > > looks like that's the rate you use), that means rviz only stores >> 0.2 >> > > seconds worth of laser scans. So when your laser scans are more >> than >> > > 0.2 seconds ahead of your tf transforms, rviz would be unable to >> > > transform any laser scans. To find out if this is the problem >> > you hare >> > > seeing, you should modify the timestamps of your laser scan >> > messages, >> > > by deducting something like 1 second from each timestamp before >> > > sending out the message from the laser scanner driver. Or you >> could >> > > create a node that takes in laser scanner messages, modifies the >> > > timestamp, and send out the modified laser scans. >> > > >> > > Wim >> > > >> > > >> > > On Thu, May 20, 2010 at 9:33 AM, Jan Elseberg >> > > > > > wrote: >> > > >> > >> Hi, >> > >> >> > >> the issue occurs when using rviz on a seperate computer >> > (synchronized to the >> > >> robot with ntp) as well as when used only on the robot. The >> > tf-tree of rviz >> > >> is attached, it is the same as before. >> > >> >> > >> Jan >> > >> >> > >> Tully Foote wrote: >> > >> >> > >>> Jan, Are you running rviz on a seperate machine? If so make >> > sure that the >> > >>> clocks are synced using ntp or similar between the multiple >> > machines. >> > >>> To see the tf tree that rviz is using try running "view_frames >> > >>> --node=rviz_******" where ******* is the UUID of the anonymous >> > rviz process >> > >>> which you can get from rosnode list. >> > >>> Tully >> > >>> >> > >>> On Thu, May 20, 2010 at 9:19 AM, Jan Elseberg >> > >>> > > >> > > > >> >> > >>> wrote: >> > >>> >> > >>> Wim, >> > >>> >> > >>> the timestamps of the laser scans are concurrent to the >> > ones I'm >> > >>> getting >> > >>> with "rostopic echo /tf". >> > >>> I was under the impression that tf would give me an error >> > of some kind >> > >>> in this scenario ? >> > >>> Also, if the issue lies with my tf-tree, shouldn't there be >> > similar >> > >>> problems in my node >> > >>> that transforms the laser scans into the /map frame using the >> > >>> tf::TransformListener ? >> > >>> >> > >>> Regards, >> > >>> >> > >>> Jan >> > >>> >> > >>> >> > >>> >> > >>> Wim Meeussen wrote: >> > >>> > Jan, >> > >>> > >> > >>> > Your tf tree looks fine, but it is possible that the >> > timestamps of >> > >>> > your laser scans are wrong. Your tf buffer keeps a >> > 10-seconds window >> > >>> > of transformations. When the timestamp of your laser scan >> > does >> > >>> not fit >> > >>> > in that 10 seconds window, tf won't be able to transform >> it. >> > >>> From the >> > >>> > data you sent, it looks like your tf buffer is nicely >> > synchronized >> > >>> > with the current time in your system, so I would suspect >> > that your >> > >>> > laser scans have timestamps that are either more than 10 >> > seconds in >> > >>> > the past, or some number of seconds in the future. >> > >>> > >> > >>> > You can check the timestamp of your laser scans using >> > "rostopic echo >> > >>> > laser_scan/header/stamp". >> > >>> > >> > >>> > Wim >> > >>> > >> > >>> > >> > >>> > >> > >>> > >> > >>> >> I've attached the results of view_frames. I have also >> > tried the >> > >>> other stuff >> > >>> >> on the troubleshooting guide. Transformations between >> > the laser >> > >>> frame and >> > >>> >> every other frame work fine. Across the longest tf-chain >> > >>> (/front_laser to >> > >>> >> /map) the average delay is approx 25ms and the maximal >> > delay is >> > >>> approx. >> > >>> >> 55ms. From this it appears to me that the tf-tree is >> > correctly >> > >>> set up, but >> > >>> >> maybe there is something else I can check? >> > >>> >> >> > >>> >> Regards, >> > >>> >> >> > >>> >> Jan Elseberg >> > >>> >> Eitan Marder-Eppstein wrote: >> > >>> >> >> > >>> >>> Jan, >> > >>> >>> >> > >>> >>> It sounds like something may be wrong with your transform >> > >>> tree. Can you >> > >>> >>> try running "rosrun tf view_frames"? This will generate >> > a PDF >> > >>> of the current >> > >>> >>> transform tree structure. You may also want to check the >> > >>> troubleshooting >> > >>> >>> link on the sidebar of this page: http://www >> > .ros.org/wiki/tf >> > >>> >> > >>> >>> for more information on useful >> tf >> > >>> debugging >> > >>> >>> strategies. >> > >>> >>> >> > >>> >>> Hope this helps, >> > >>> >>> >> > >>> >>> Eitan >> > >>> >>> >> > >>> >>> >> > >>> >>>> On May 20, 2010 3:38 AM, "Jan Elseberg" >> > >>> > > >> > >>> > > > >> > >>> >>>> > > >> > >>> > > >>> wrote: >> > >>> >>>> >> > >>> >>>> Hi everyone, >> > >>> >>>> >> > >>> >>>> I am trying to get our robot to work with the navigation >> > >>> stack of ros. >> > >>> >>>> I've been following the tutorial on >> > >>> >>>> http://www.ros.org/wiki/navigation/Tutorials/RobotSetup. >> > >>> After setting >> > >>> >>>> up the robot with a tf-tree and sensor nodes , I have >> > noticed >> > >>> a problem >> > >>> >>>> with rviz. I am unable to display the laserscan >> > messages in >> > >>> any frame >> > >>> >>>> other than the laser coordinate system itself, i.e., >> > whenever >> > >>> I select a >> > >>> >>>> other than /front_laser the status of >> > the laser >> > >>> scan >> > >>> >>>> display shows the error: >> > >>> >>>> >> > >>> >>>> "Unknown reason for transform failure". >> > >>> >>>> >> > >>> >>>> Also, this warning appears in the bash: >> > >>> >>>> >> > >>> >>>> [WARN] 1274341043.701801000: MessageFilter >> > [target=/base_link >> > >>> ]: Dropped >> > >>> >>>> 99.03% of messages so far. Please turn the >> > >>> [ros.rviz.message_notifier] >> > >>> >>>> rosconsole logger to DEBUG for more information. >> > >>> >>>> >> > >>> >>>> Doing so gives me these repeating debug messages: >> > >>> >>>> >> > >>> >>>> MessageFilter [target=/base_link ]: Added message in >> frame >> > >>> /front_laser >> > >>> >>>> at time 1274341252.994, count now 10 >> > >>> >>>> MessageFilter [target=/base_link ]: Removed oldest >> message >> > >>> because >> > >>> >>>> buffer is full, count now 10 (frame_id=/front_laser, >> > >>> >>>> stamp=1274341252.813649). >> > >>> >>>> >> > >>> >>>> This suggests a problem with the tf-tree to me. >> > However, when >> > >>> using the >> > >>> >>>> "transformPoint(...)" function of >> > tf::TransformListener in my >> > >>> own nodes >> > >>> >>>> to transform the laser scan into the global frame >> > everything >> > >>> works as >> > >>> >>>> intended with no errors/warnings. >> > >>> >>>> >> > >>> >>>> Does someone have an idea what I am doing wrong? >> > >>> >>>> >> > >>> >>>> Thank you for any help! >> > >>> >>>> >> > >>> >>>> >> > >>> >>>> Jan Elseberg >> > >>> >>>> >> > >>> >>>> _______________________________________________ >> > >>> >>>> ros-users mailing list >> > >>> >>>> ros-users@code.ros.org >> > > >> > >>> > > > > >> >> > >>> >>>> https://code.ros.org/mailman/listinfo/ros-users >> > >>> >>>> >> > >>> >> _______________________________________________ >> > >>> >> ros-users mailing list >> > >>> >> ros-users@code.ros.org >> > > >> > >>> >> https://code.ros.org/mailman/listinfo/ros-users >> > >>> >> >> > >>> >> >> > >>> >> >> > >>> > >> > >>> > >> > >>> > >> > >>> > >> > >>> >> > >>> _______________________________________________ >> > >>> ros-users mailing list >> > >>> ros-users@code.ros.org >> > > >> > >>> https://code.ros.org/mailman/listinfo/ros-users >> > >>> >> > >>> >> > >>> >> > >>> >> > >>> -- >> > >>> Tully Foote >> > >>> Systems Engineer >> > >>> Willow Garage, Inc. >> > >>> tfoote@willowgarage.com >> > > >> > >>> (650) 475-2827 >> > >>> >> > >> _______________________________________________ >> > >> ros-users mailing list >> > >> ros-users@code.ros.org >> > >> https://code.ros.org/mailman/listinfo/ros-users >> > >> >> > >> >> > >> >> > > >> > > >> > > >> > > >> > >> > _______________________________________________ >> > ros-users mailing list >> > ros-users@code.ros.org >> > https://code.ros.org/mailman/listinfo/ros-users >> > >> > >> >> _______________________________________________ >> ros-users mailing list >> ros-users@code.ros.org >> https://code.ros.org/mailman/listinfo/ros-users >> > > > _______________________________________________ > ros-users mailing list > ros-users@code.ros.org > https://code.ros.org/mailman/listinfo/ros-users > > -- Tully Foote Systems Engineer Willow Garage, Inc. tfoote@willowgarage.com (650) 475-2827