SL Remy's profile - activity

Hello, I've noticed that on my install (fuerte from debs, quadrotor from svn -r 403), according to the "ground truth state", the quadrotor slowly drifts when not provided with a control input.

The onboard camera confirms this motion as well.

Is this something that others have observed, or can repeat?

 roslaunch hector_quadrotor_demo outdoor_flight_gazebo.launch & 
 rostopic echo -p /ground_truth/state/pose/pose/position/z

To be clear, so far, publishing '[0.0,0.0,0.0]' '[0.0,0.0,0.0]' doesn't appear to change the outcome for me, but other non-zero control do. (still trying to clear this up)

The first seven seconds of the position data also have some interesting dynamics, which I assume are because the odom messages have not yet been published. If this is the case, is this an example of how numerical uncertainty grows in the physics engine?

Not sure how long this has been in the "stack" but does the existence of pantilt.inc and the ModelCamera definition in stage.hh mean that there is now hope for subscribing to camera images in stage?

If so, should this be some sort of plugin ala gazebo, or a new addition to stageros.cpp?

The issue also has code, so you can patch yourself if you're in a hurry.

I have gotten this message regularly when running in VirtualBox on one particular machine I use. I regularly use VMs on

It may be significant that your ros_master_uri is different from your ros_hostname.. the ros_master_uri is saying where

Hello all, I observe the following when trying to test out the new version of the most excellent hector_quad_rotor sudo apt-get install ros-hydro-hector-quadrotor-demo.

user@happyplace:~$ roslaunch hector_quadrotor_demo outdoor_flight_gazebo.launch 
... logging to /home/ubuntu/.ros/log/297f0af6-c010-11e3-8a21-fa163eaa4736/roslaunch-10-100-16-5-23452.log
Checking log directory for disk usage. This may take awhile.
Press Ctrl-C to interrupt
Done checking log file disk usage. Usage is <1GB.

Invalid <arg> tag: hector_quadrotor_description
ROS path [0]=/opt/ros/hydro/share/ros
ROS path [1]=/opt/ros/hydro/share
ROS path [2]=/opt/ros/hydro/stacks. 

Arg xml is <arg name="model" value="$(find hector_quadrotor_description)/urdf/quadrotor_hokuyo_utm30lx.gazebo.xacro"/>

It seems that ros-hydro-hector-quadrotor-description should be a dependency. Can anyone else confirm this experience?

I just installed ros-hydro-stage-ros, but I can't seem to find roscd.

What do you see when you type apt-get install ros<\tab> (i.e. press the tab key)?

You might want to take a look a the venerable rosbridge. It provides a "a JSON API to ROS functionality for non-ROS programs".

Roughly translated, this means that you can monitor your robot through the internet.. That said.. I hope that latency isn't a concern. Security and privacy would also be issues at various points in the application as well, but it can be done.

Rosbridge Quick App: iPhone Control https://www.youtube.com/watch?v=fUNF2...

Henry Evans and Chad Jenkins: Meet the robots for humanity https://www.youtube.com/watch?v=aCIuk...

I'd suggest using plain old roslaunch xml.. You can create launch files for the modules, and then you can create a launch file that includes in a "large" launch file. This way you can compose your application as needed. You can also run the launch files for the individual modules yourself at the command prompt, if you'd like to "hotswap" functionality.

You can also have multiple launch files for the different use cases.. take a look at the hector_quadrotor project for some really cool examples.

Hope this helps!

I also notice that on my machine, python2 and python2.7 somehow do different things.... So python -c "import rospkg" works, but python2.7 -c "import rospkg" does not... (just in case this isn't weird enough!)

I've had a case where I was not able to read some of the directories in dist-packages so when I did an import of that module, python was unable to do so. This is the reason why I was asking about the permissions.

Can you explain a little more about the motivation for the request? For example, if a node is already running, will you want the "launch file" do something different?

What are the permissions on /usr/lib/python2.7/dist-packages/rospkg ?

Hello! This answer doesn't really make it clear what was done to address the problem. Is it possible to provide greater detail?

Hello all, I've noticed that cmvision is a package listed on the ROS wiki, but there seems to be no "current" instructions on how to install the code.

I did come across an older clone of the wiki which lists the package, but that code didn't build:

  In file included from /.../ros-stacks/cmvision/src/color_gui.cpp:34:0:
  /.../ros-stacks/cmvision/src/cmvision_color_blob_finder.h:31:32: fatal error: cv_bridge/CvBridge.h: No such file or directory
  compilation terminated.
  In file included from /.../ros-stacks/cmvision/src/main.cpp:24:0:
  /home/ubuntu/ros-stacks/cmvision/src/cmvision_color_blob_finder.h:31:32: fatal error: cv_bridge/CvBridge.h: No such file or directory
  compilation terminated.
  In file included from /.../ros-stacks/cmvision/src/color_gui.cpp:34:0:
  /.../ros-stacks/cmvision/src/color_gui.h:34:32: fatal error: cv_bridge/CvBridge.h: No such file or directory
  compilation terminated.

It looks like opencv has changed a smidge since this package was written so it would need to be updated... Is there an updated repo somewhere else? Has the package been made obsolete by something else? Any pointers?

(And yes I did see the homebrew post, but the instructions aren't current either.

Hi there, the two listed packages include the publishers (you'd just need to point to the right device..). As far as the subscriber/client goes, take a look at http://wiki.ros.org/cv_bridge

Topics are an essential communications resource in ROS. I'm assuming that you mean that you'd like to save/store the data from odom not just "look" at it with rostopic? (Can you clarify what you need?)

Hello! Did a MORSE implementation ever get implemented? (and did you have to install MORSE from source to get this done?)

For completeness sake, what version of ROS/Gazebo are you using? How did you install the hector_quadrotor_gazebo package (e.g. apt-get, source etc.)? Were you successful and did the answer below help you?

Just in case anyone in the present is checking, stageros does have a camera sensor these days.

The code is:

ros::NodeHandle nh_private("~");     
bool state=false;

nh_private.param<bool>("state", state, "false");

It turns out the "state" is "true". Why???

If you issue a Twist message with a non-zero velocity and the observed velocity is zero (your robot isn't moving), then you can infer that you've hit an obstacle. For willow-four-erratics.world, /robot_0/odom provides information about robot_0. Subscribe to it and compare with the desired value.

You might need to post this question on http://answers.gazebosim.org/questions

Was this question every resolved?

Your robot controller could subscribe to the odom topic (it's already publishing to the the cmd_vel topic). Since it knows what the robot should be doing, it can detect that the commanded velocities are not being observed. rostopic list should let you know all the topics that you can use.

As a general note, the best source for Stage details is github, but it's embedded in model_draw.cc. stageros doesn't publish this information. The condition is identified in model_position.cc.

You could modify stageros.cpp to detect when a model is stalled (collisions) and to publish a message on a topic.

As a final note, you could also just evaluate the /robot_X/odom message and compare the observed velocity to the intended velocity of the robot. (Compare the embedded twist message to the twist command that you issued.)

Setting the voltages and (possibly even) getting feedback from the Integrated dual quadrature decoders are tasks that make sense using topics (publishing and subscribing). If there are configuration changes (control options?) this seems to be a task that is reasonable for service calls.

This seems like it would be really fun in our community!

The Leap technology is 200 times more accurate than anything else on the market — at any price point. Just about the size of a flash drive, the Leap can distinguish your individual fingers and track your movements down to a 1/100th of a millimeter.

Company website