Sagnik's profile - activity

Hi,

I am trying to initialize a costmap_2d with a static map which is being published by map_server. Could someone point me to how this would be done?

I understand that I need to run a map_server node which publishes /map and /map_metadata topics. Also I realise that I need to use a tf::TranformListener to get the map data to the costmap. Is that correct ? Any help would be appreciated.

Thanks, Sagnik

Hi,

I was trying to use sbpl_lattice_planner path planning on a 4-wheeled car-like robot. I was testing it using the example simulation given in Sec 2.2.1 at this URL. I have a few questions regarding that.

• It seems to me that the planner re-plans during the actual execution of motion from start to goal. Is that correct ? If it is, is there a way to switch off that feature and have it generate only one plan in the beginning ?
• Is there a way to get the plan (in terms of (x,y,theta)) without actually having the robot move from start position to goal ?
• Finally, I did not find a .mprim file (or a .m mprim generation file) for a 4 wheeled robot (Ackerman Steering/Bicycle model). Could someone point me to one that exists ?

Thanks, Sagnik

Hi,

I was looking for a ROS package which I could use as a Controller for a 4-wheeled indoor car-like robot.

We have a system which integrates a path planner, localizer, controller and other modules needed for navigation. However, the Controller doesn't work too well. Hence I was thinking if i could use another Controller and maybe modify that to the project's needs, it might work better.

In that regard, how feasible is it to use the art_nav package (which was built for the ART autonomous vehicle) for a generic 4-wheeled robot ? Is there some Documentation for the design of the algorithm ?

Are there any other Controllers ROS packages that I should take a look at ?

Thanks, Sagnik

Hi,

I would like to use Stage to simulate a robot with a camera (or a blob-finder) as a sensor. I have added a camera in the world file but I am not able to get camera data published on the /camera/image_raw and other camera sensor topics. With a real-life camera on a robot, I would assume one would have to install the necessary driver for the camera and start it get data published on /camera/image_raw. Do I need to install any camera driver for this arbitrary camera ? What am I missing here ?

Thanks, Sagnik

Hi,

I tried out the Erratic simulation using Stage and it works fine. But for some reason the visualization of the laser beams (as shown in the sample Stage output on SimulatingOneRobot ) don't show up. That seems to be a nice feature to have for a simulation. Has the feature been removed in CTurtle or do I need to make some changes to the .world file to see this.

Thanks, Sagnik

Hi Guys,

I wanted to modify stageros.cpp in a very minor way. I wanted the /odom topic to be published with a different name, so I went ahead and changed the string at the top of the file to "canbus". After rosmaking stage, it seg faults at startup. Even when I change the string "canbus" back to "odom" and rosmake it once again, it still seg faults.

I checked the seg fault issue of stage listed on the stage page on the ros site, but thats not the problem in my case.

Where am I going wrong ?

The backtrace is as follows,

Core was generated by `./stageros ../world/try.world'.
Program terminated with signal 11, Segmentation fault.
#0  boost::shared_ptr<ros::Publisher::Impl>::operator! (this=0x0, message=...) at /usr/include/boost/smart_ptr/detail/operator_bool.hpp:55
55          return px == 0;
(gdb) bt
#0  boost::shared_ptr<ros::Publisher::Impl>::operator! (this=0x0, message=...) at /usr/include/boost/smart_ptr/detail/operator_bool.hpp:55
#1  ros::Publisher::publish<nav_msgs::Odometry_<std::allocator<void> > > (this=0x0, message=...) at /opt/ros/cturtle/ros/core/roscpp/include/ros/publisher.h:95
#2  0x000000000040e7f1 in StageNode::WorldCallback (this=0x7fff89629870) at /opt/ros/cturtle/stacks/simulator_stage/stage/src/stageros.cpp:355
#3  0x000000000041c2ac in StageNode::s_update (world=<value optimized out>, node=0x1fae778) at /opt/ros/cturtle/stacks/simulator_stage/stage/src/stageros.cpp:88
#4  0x00007f38f712322e in Stg::World::CallUpdateCallbacks (this=0x13ca4d0) at /opt/ros/cturtle/stacks/simulator_stage/stage/build/Stage-3.2.2-Source/libstage/world.cc:481
#5  0x00007f38f7123604 in Stg::World::Update (this=0x13ca4d0) at /opt/ros/cturtle/stacks/simulator_stage/stage/build/Stage-3.2.2-Source/libstage/world.cc:552
#6  0x00007f38f713c501 in Stg::WorldGui::Update (this=0x13ca4d0) at /opt/ros/cturtle/stacks/simulator_stage/stage/build/Stage-3.2.2-Source/libstage/worldgui.cc:364
#7  0x00007f38f6a2f008 in Fl::wait(double) () from /usr/lib/libfltk.so.1.1
#8  0x0000000000414984 in main (argc=2, argv=<value optimized out>) at /opt/ros/cturtle/stacks/simulator_stage/stage/src/stageros.cpp:440

Thanks, Sagnik

Hi,

I want to simulate a custom robot using ROS Diamondback. I figured that Stage is the package I should be using for simulation. I have read up the documentation on setting up a .world file for my simulation and have a world file with a robot and the intended simulation arena. However I am stuck as to how to proceed further. I have some code which does controlling/path planning for my robot, but how do I integrate the code with Stage ?

Could someone point me to some documentation / How-tos on this ?

Thanks, Sagnik

I am trying to install rviz on ROS Diamondback (on a 64 bit Mac Snowleopard). I get this link error related to Ogre::Rectancle2D when I run,

"rosmake rviz"

Error mesg:

Undefined symbols:

"Ogre::Rectangle2D::Rectangle2D(bool)", referenced from: rviz::SelectionManager::initialize() in selection_manager.o

Any idea why it cant find the Rectangle2D symbol (specifically) in Ogre ?

When I comment all the occurrences of Rectangle2D (jus to see it build completely! ) and run it using,

"rosrun rviz rviz"

It complains that it cant find the Ogre library.

Error msg:

dyld: Library not loaded: @executable_path/../Frameworks/Ogre.framework/Versions/1.7.2/Ogre

I have built Ogre 1.7.2 manually (as the 1.7.1 version which comes with ROS does not build on 64 bit).

Can anyone tell me where exactly do I need to put the Ogre libraries for rviz to work ?

Hi,

I was trying to install the nav_view package on ROS Diamondback on a 64 bit mac Snowleopard. However this is what I see,

j0813563:~ sagnikdhar$ rospack find nav_view [rospack] couldn't find package [nav_view]

Has nav_view been deprecated ? If yes, what is the alternative package for Visualization applications ?

Thank you.

~ Sagnik

Hi,

I am trying to build ogre_tools using the source present in ROS Diamondback on a 64bit Mac SnowLeopard. I have successfully installed Ogre (after fetching the latest version from their repo) and have placed the Ogre.framework where the ogre_tools build process looks for it. However, I am stuck with this error now,

..... Some output from the make command.... make -f CMakeFiles/python_ogre_tools.dir/build.make CMakeFiles/python_ogre_tools.dir/depend /opt/local/bin/cmake -E cmake_progress_report /Users/sagnikdhar/ros/visualization_common/ogre_tools/CMakeFiles 20 [ 94%] Generating src/ogre_tools/ogre_tools_swig_generated.cpp, lib/ogre_tools.py /opt/local/bin -c++ -Wall -python -modern -new_repr -keyword -fastdispatch -fvirtual -fastinit -fastunpack -I/opt/local/lib/wx/include/gtk2-unicode-release-2.8 -I/opt/local/include/wx-2.8 -D_FILE_OFFSET_BITS=64 -D_LARGE_FILES -D__WXGTK__ -DSWIG_TYPE_TABLE=_wxPython_table -DWXP_USE_THREAD=1 -o /Users/sagnikdhar/ros/visualization_common/ogre_tools/src/ogre_tools/ogre_tools_swig_generated.cpp -outdir ../lib -module ogre_tools /Users/sagnikdhar/ros/visualization_common/ogre_tools/src/ogre_tools/ogre_tools.i

make[2]: /opt/local/bin: Permission denied

make[2]: * [src/ogre_tools/ogre_tools_swig_generated.cpp] Error 1

make[1]: * [CMakeFiles/python_ogre_tools.dir/all] Error 2

make: * [all] Error 2

Any idea what is going wrong ?

I found a discussion thread which discusses a similar problem, however the solution points to a ticket (Ticket ID 818) on the WillowGarage site, but the link seems broken. Any idea how I could track an older ticket on the Willow Garage site ?

Thanks a lot !

~ Sagnik

Hi,

I am trying to simulate a car-like robot using Stage. I have a .world file which sets up the environment and the robot. I also have some Controller code which publishes commands to a topic for moving forward and/or turning at some velocity. Finally I have some interface code which subscribes to these commands and publishes to /cmd_vel to make the robot move inside the Stage window. My questions regarding this are:

• Is /cmd_vel the topic I should be publishing messages to , for moving the robot around ? Or is it some other topic ? (I assumed it was /cmd_vel as that is the only topic Stage subscribes to.)

• Assuming /cmd_vel is the topic I should publish to, I notice that I need to keep publishing (in a loop) to /cmd_vel for the robot to move. I would assume that if I set the velocity to be X, it would keep moving at X, and then stop when I set it to 0. But that is not the case. Is there something I am not understanding here ? (Publishing a velocity to the /cmd_vel once moves it only for a small distance and then stops )

• Finally, I did not find enough documentation which would explain what exactly is "angular" velocity in /cmd_vel for a car-like robot ? Is it the Steering angle or the actual angle of the robot ?

Follow-up questions:

In my Car-like robot simulation, I would like to specify different velocities to cmd_vel to move my robot around. So after specifying a velocity V1, I would like the robot to keep moving at V1 till I explicitly specify it to change to velocity V2.

I understand ~/base_watchdog_timeout parameter is a way to specify how long I want my last command to be effective. But setting this parameter would affect other messages published on other topics too.

I was looking for some way to specify in the 'roscpp::publish()' api to specify the rate at which a message should be published, (in a way similar to the '-r' option of the "rostopic pub" command). Any ideas ?

I had a another question regarding /cmd_vel. What is the unit of the linear velocity in /cmd_vel that Stage expects ? Is it meters per sec ?

Hi,

I am developing a path-planner for a 4 wheeled car-like robot. I have a 2D map of the environment with the initial coordinates of the robot and the final coordinates known. A straight-forward solution would be to use A* or any general path planning algorithm like it, but the challenge I see is in ensuring that the curvature in the path is achievable by a 4 wheeled (non-holonomic) robot.

Also, as a second step, the robot uses a visual marker (hung on a wall in front of it) to localize itself. So the path planned should ensure that the robot's heading is such that the marker is always in view.

Does ROS have packages that I could use or take ideas out of ?

Thanks, Sagnik