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 > >