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2015-02-02 18:21:25 -0500 answered a question Cartesian velocity control of robot arm

I actually found a good solution to this in the code for pr2_teleop_general. The basic idea is to:

  1. Grab the current robot state using RobotCommander.get_current_state()
  2. Call the GetPositionFK service of your move_group to get the the end effector position using this state as input.
  3. Scale your Cartesian velocity by a constant and add it onto this position. Call the GetPositionIK service of your move_group to get an inverse kinematics solution for this.
  4. Subtract your current joint angles from the IK joint angles, and multiply by some constant to get a velocity for every joint.
2015-02-01 20:23:05 -0500 asked a question Cartesian velocity control of robot arm

I have a 6DOF robot arm, and would like to start driving the end effector around with a joystick. I think the most natural way to do this would be to map my joystick axes to Cartesian velocities of the end effector. I have tried executing very small paths in the desired directions using MoveGroupCommander.compute_cartesian_path(), but I end up getting very jumpy results. Are there any facilities built into MoveIt or otherwise to help me do this?

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2015-01-21 14:10:02 -0500 answered a question rviz black background in menu

I had the same problem running Cinnamon on Ubuntu 14.04 with my GeForce GT 650M (Mac Edition). I fixed it by running:

  gtk-theme-config

and then turning "Custom Panel Colors" to on.

Theme Configuration Panel

2014-02-19 11:50:13 -0500 commented answer hydro + kinect + Ubuntu 12.04 library issue?

I had the exact same problem as bchr, and this solved it. I think this should be the accepted answer.

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2013-10-11 10:34:22 -0500 commented answer Installing Stacks in Hydro

The --exclude RPP argument gets me a "rosinstall_generator: error: too few arguments" As a larger question, is installing each new package in its own separate workspace the recommended way to organize things? If not, how do I add new packages to an existing workspace?

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2013-10-11 09:38:26 -0500 asked a question Installing Stacks in Hydro

Sorry if this is a total noob question, but I can't seem to find a straightforward answer anywhere. I have ROS install on my mac, and I'm trying to get some new stacks. What is the correct way to check out and build stacks using ROS Hydro? I have a ros_catkin_ws setup in my home directory as described in the hydro/Installation/OSX/Homebrew/Source documentation.

For example, I want to grab the camera1394 stack so I did the following

cd ~/ros_catkin_ws/src
rosws set camera1394 --git https: //github.com/ros-drivers/camera1394.git
rosws update camera1394
cd ~/ros_catkin_ws
catkin_make camera1394

(There's an extra space in the git repo address b/c this site won't let me post links)

The final catkin_make command spits out the following error

CMake Error at catkin/cmake/catkin_workspace.cmake:88 (message): This workspace contains non-catkin packages in it, and catkin cannot build a non-homogeneous workspace without isolation.

If I instead try to rosmake camera1394 I get the following:

[ rosmake ] WARNING: The following args could not be parsed as stacks or packages: ['camera1394']
[ rosmake ] ERROR: No arguments could be parsed into valid package or stack names.

Interestingly, if I just try to roscd camera1394 I get the following error

roscd: No such package/stack 'camera1394

even though ls ~/ros_catkin_ws/camera1394 shows that the package is there.

My $ROS_PACKAGE_PATH variable is currently set to /Users/rand/ros_catkin_ws/install_isolated/share:/Users/rand/ros_catkin_ws/install_isolated/stacks by the ~/ros_catkin_ws/install_isolated/setup.bash script.

2013-10-09 08:19:41 -0500 commented question malloc error when running roscd and rospack

I'm having the same issue - did you ever find a solution?

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