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2015-03-15 15:32:30 -0500	received badge	● Good Answer (source)
2012-10-06 05:43:25 -0500	received badge	● Good Answer (source)
2012-07-24 04:52:49 -0500	received badge	● Good Answer (source)
2011-12-19 00:34:10 -0500	received badge	● Good Answer (source)
2011-12-08 22:14:41 -0500	received badge	● Nice Answer (source)
2011-10-24 20:53:29 -0500	received badge	● Nice Answer (source)
2011-10-11 07:01:00 -0500	answered a question	Pr2 whirling like a dervish Lorenzo, you should try the "base_local_planner", which was default until cturtle. It does not have this spinning problem at all. The DWA local planner can be fun to watch, but you might be bored of this spinning behavior. The default configuration file in pr2_navigation_config/move_base/base_local_planner_params.yaml will work well, but if you add the parameter "min_vel_x" to "0.10", the planner will be slightly more robust.
2011-10-10 10:49:50 -0500	received badge	● Good Answer (source)
2011-10-06 17:26:42 -0500	received badge	● Nice Answer (source)
2011-09-01 04:16:28 -0500	received badge	● Nice Answer (source)
2011-08-24 11:30:47 -0500	answered a question	initialize pr2 posture in gazebo See the gazebo/set_model_configuration service: http://www.ros.org/doc/api/gazebo/html/srv/SetModelConfiguration.html http://www.ros.org/wiki/gazebo
2011-07-28 09:29:03 -0500	answered a question	point cloud height problem Changing the mechanical reduction of the torso is only going to mask other problems. The mechanical reduction numbers for your robot will never change, even after calibration. Recalibrating the robot only changes the offsets of each joint. Thank you for bringing this to my attention. I'm going to investigate this value and make sure the mechanical reduction is correct for the PR2 torso.
2011-06-21 17:42:03 -0500	answered a question	cameracalibrator.py doesn't work with --no-service-check? PRP, can you be sure that the image messages are actually being published? If that doesn't work, I would suggest pressing "ctrl-C" to see where the node is stopped. If you find a bug in the calibration script, file a ticket at code.ros.org/trac/ros-pkg.
2011-06-08 17:26:15 -0500	answered a question	Which database system suits ROS better? Victor, have you seen the "web_bags" package? https://code.ros.org/svn/wg-ros-pkg/branches/trunk_cturtle/stacks/web_bags It is unsupported and unmaintained, but it could give you a starting for a system like you're proposing.
2011-06-06 20:13:40 -0500	received badge	● Critic (source)
2011-05-17 13:47:52 -0500	commented answer	Face Recognition with Kinect Xi, check that the topics are named correctly using "rxgraph". I think the default topic names changed since I posted the code.
2011-04-27 07:47:00 -0500	received badge	● Nice Answer (source)
2011-04-24 19:25:37 -0500	received badge	● Nice Answer (source)
2011-04-23 18:20:08 -0500	answered a question	Can gazebo_ros actually use bullet? According to the Gazebo roadmap, full Bullet support is a long-term goal. http://www.ros.org/wiki/simulator_gazebo/Roadmap
2011-04-23 08:26:57 -0500	answered a question	simulating kinect sensor in Gazebo If you use the SVN branch for "kt2_simulator" (referenced above by Stefan), you can use the "gazebo_ros_wge100" plugin to simulate an RGBD camera. You can look in the package "kt2_pr2_defs" for information on how to configure a URDF/Gazebo model entry for the camera. The camera will publish camera info, images, disparity, and points2. The changes in that branch will be merged in to trunk soon. I don't think the gazebo_ros_wge100 camera plugin follows the same topic name conventions as a Kinect, but it should be easy to solve by remapping.
2011-04-21 06:42:37 -0500	received badge	● Great Answer (source)
2011-04-21 06:42:37 -0500	received badge	● Guru (source)
2011-04-19 18:22:36 -0500	answered a question	diamondback stereo_image_proc and GPU Sean- Victor from OpenCV and I set up that package for benchmarking. If you look at the code, that package uses a modified version of stereo image proc that runs on the GPU with CUDA. That package was never designed to be released. I believe OpenCV has released GPU implementations of several algorithms, including stereo block matching (or they may be scheduled to release them soon). I don't think these algorithms have been integrated with ROS's stereo_image_proc, but you could probably patch it fairly easily since they probably have identical API's. If you create any patches, open a ticket in ros-pkg. Kevin
2011-04-18 07:34:12 -0500	received badge	● Good Answer (source)
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2011-04-17 22:36:44 -0500	received badge	● Nice Answer (source)
2011-04-17 20:21:34 -0500	answered a question	How can I speed up simulation in Gazebo? Stefan- I spent some time early this year working configurating Gazebo to run faster with the PR2 model. Basically, my approach was to downsample sensors as much as possible, downsample physics, and then patch Gazebo as needed where the profile showed huge hits. Like you, my application is teleoperation. With a powerful machine, Gazebo can run at real time or faster (I run at 1.4x real-time using an Intel i7 2600K with a GT 560 Ti GPU). I would guesstimate it to run about 5x faster with the PR2 model. If you use the "kt2_simulator" branch of Gazebo, (https://code.ros.org/svn/wg-ros-pkg/branches/trunk_electric/kt2_simulator), you'll find the changes to the URDF of the PR2, controller gains, and the world file. A rosinstall file will allow you pull down the branch of Gazebo we're using. These changes should go out in Electric. The biggest gains I found found were from lowering the physics update rate from 1KHz to 250Hz. Even if you have to increase the number of quick step iterations per physics loop, decreasing the update rate is still a win because you don't have to do collision checks as often. Obviously, this can cause problems in physics quality, and objects/robots can "explode". You'll have to tune controller gains for a lower update rate. The modified gains for the PR2 are in the "kt2_pr2_defs" package in the above stack. One major improvement to PR2 physics to a "fixed joint reduction" which John put in place. The PR2 URDF calls out over 40 fixed joints (usually to connect a sensor to a body). In Diamondback, Gazebo models these joints as revolute joints. In the branch, the URDF is reduced to only bodies that are connected by revolute or prismatic joints. This increases physics-only simulation by about 50%. If you run the "urdf2model" or "spawn_model" utilities, fixed joints in your URDF will be reduced. A large performance hit to the simulator is laser scan generation. The laser data is generated with ODE collision checking, and you can see a very noticeable difference in speed when you are subscribing to the laser data. For the PR2, I cut the update rate for the lasers in half, and reduced the number of rays from 640 to 180 for each laser. These are changes to the URDF, but ideally they will be dynamically reconfigurable at some point. Camera rendering is also expensive. In the branch, I implemented a reconfigurable update rate for each camera to allow you to throttle down the render rate (this feature exists in Diamondback, but does not actually change the render rate of the camera, so does not affect the simulation speed). Slow down the camera update rates as much as you can. If you don't subscribe to a camera topic, the data won't be generated, so make sure you have lazy subscription in your pipeline. In the new branch, Gazebo cameras can generate depth data, like a Kinect. In ... (more)
2011-04-03 17:36:31 -0500	answered a question	rxbag_plugins commandline API The plugins are only for use in rxbag. You could write your own CSV export script for bag files, or just use rostopic. There is a command line option for rostopic that allows echoing a bagfile in a machine-readable format.
2011-03-21 13:33:23 -0500	received badge	● Teacher (source)
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2011-03-21 12:04:15 -0500	answered a question	How can I create robot model and simulate with ROS? You can use the Gazebo simulator with ROS: http://www.ros.org/wiki/simulator_gazebo The "Tutorials" link on that webpage has instructions for creating a robot in simulation and running it.
2011-03-21 12:02:09 -0500	answered a question	what realtime patch should I use with ROS? The PR2 kernel uses a linux-rt kernel, version 2.6.31-10-rt. We have patched it to resolve a iptables problem. We have noticed occasional kernel panics when running on the PR2, but this is the best RT kernel we have found. You can download the kernel, with headers, from the PR2 repo: http://packages.ros.org/pr2/ubuntu/ A related package in the same repo, "pr2-grant", has a set capability program to allow non-root users to run realtime programs. pr2-grant ./my_realtime_prog arg1 arg2 ... Outside the PR2, these packages are completely unsupported, but you may find them useful.
2011-02-27 07:49:00 -0500	answered a question	Face Recognition with Kinect Scott, I've been keeping an eye on your thread on ros-users. I've written a small package "face_builder" to detect faces using OpenCV and return a clustered point cloud of the face. It works as a stand-alone node, but it should also work as a library. It publishes clustered faces on the "faces" topic (type: sensor_msgs/PointCloud2) and publishes a "detected_faces" image for debugging. It builds against trunk of PCL right now and ROS Diamondback. If you need to patch it to get it to build, let me know. Not having a great place to put it, I uploaded it to the "PR" wiki: http://pr.willowgarage.com/wiki/Useful_general_references Look for "face_builder.tar" Let me know what you find with face recognition.