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2016-08-08 01:40:51 -0500 marked best answer ROS-enabled golf-car?

Hello,

I am quite interested to build a ROS-enabled golf-car, perhaps this is one step towards autonomous vehicle. I did a search and only found Grizzly from clearpath robotics is quite similar to an autonomous vehicle, but Husky can't carry passengers. My question is, is there any ros-enabled golf-car available in the market, or sth. similar? Ideas are welcome.. Thanks a Lot.

2016-08-08 01:38:51 -0500 marked best answer rviz increase network traffic on lo interface

Hi, there,

I have a robot with Velodyn 32E installed. This laser outputs data at around 18Mbps. In my configuration, the robot is configured as ROS master, a base station computer is configured as a client. When I start the launch file to launch the velodyne laser driver node at the robot side, I also run the rviz at my base station side. Now, I have an interesting observation, once I start rviz, even without subscribe to anything, the loopback (lo) network interface at my base station computer shoots up to 18Mbps. What happened here? Thanks a lot.

UPDATE:

<launch> 
  <arg name="pcap" default=""/> 
  <arg name="calibration" default="$(find velodyne_pointcloud)/params/32db.yaml"/> 
  <include file="$(find velodyne_driver)/launch/nodelet_manager.launch"> 
    <arg name="model" value="32E"/> 
    <arg name="pcap" value="$(arg pcap)"/> 
  </include> 
  <include file="$(find velodyne_pointcloud)/launch/cloud_nodelet.launch"> 
    <arg name="calibration" value="$(arg calibration)"/> 
  </include> 
</launch>
2016-08-08 00:36:48 -0500 marked best answer Large-Scale SLAM?

Hello, all,

I have been testing various SLAM packages in ROS. I am just wondering is there any "large-scale" SLAM packages available? By large-scale I mean the map produced can be as large as a few kilometer^2 and the occupany grid map can be overlaid on a GIS software. Currently it seems to me that all packages can only produce a relatively small map, for example, 50 meters x 50 meters. I understand that large map construction will increase memory and cpu usage. So, is there any efficient way to do that?

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2014-01-28 17:31:45 -0500 marked best answer octomap in dynamic environment

Hi,All,

I am using a 3D lidar together with octomap package to build a 3D map for an indoor environment. Since my lidar is stationary, I actually don't need any transform between lidar frame and map frame. Everything works fine except that when there are moving objects, the 3D map produced seems to be messy. Those occupied cells are not cleared even when the moving objects moved away. I know this has sth to do with the update rule of the octomap and I have been trying to play around with the octomap parameters but no success. What am I missing here? Thanks a lot!

My platform: Ubuntu 12.04, ROS Fuerte, Octomap is the one checked out from ROS wiki page.

2014-01-28 17:31:29 -0500 marked best answer RGBDSLAM map recording

Hi, All,

I am able to run rgbdslam (with openni camera) on fuerte. My question is how can I save the 3d map (as a video?) that is been built. I thought about using rosbag to record all published topics, but how can I visualize the 3D map? I know I can visualize octomap related topics in rviz, what about the 3D map with the image overlay (the map on the rgbdslam GUI)? Thanks a lot for the help.

2014-01-28 17:26:49 -0500 marked best answer Setting up tf for Hector SLAM

Hi, all,

I am trying to get my hokuyo laser node to work with hector_slam to produce realtime SLAM. I have installed hokuyo_node and the laser seems working properly. I also completed the hector_slam tutorial using the "Team_Hector_..bag" file. However, when I rosrun hokuyo_node and hector_slam(through a launch file), I just can't get it right. My launch file settings are as follows:

Then I went back to rerun the hector_slam tutorial, I use rxgraph to check what the nodes/topics are. Then, I found that a "/play node" (play back of the *.bag file in the tutorial) publish a '/tf' topic and "/hector_mapping" node subscribe to it. If I just rosrun hokuyo_node, then the "/hokuyo_node" just publish the '/scan' topic. I guess the problem is here. Can anyone elaborate a little more on this '/tf' and how to resolve it when using real laser scanners? THANKS A LOT.

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2013-11-27 13:53:27 -0500 commented answer hector exploration error msgs

I know what went wrong. In the costmap file of the hector explore, there is one parameter called update frequency. The default is set to 0.5. When I use 0.5 HZ, I always get a warning : Map update loop missed its desired rate of 0.5000Hz... the loop actually took 3.6498 seconds That's why I changed to 0.2 and the robot can't start to explore (above mentioned error messages). When I change to back to 0.5, the robot can start to explore, but with this warning message.

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2013-11-25 20:03:55 -0500 asked a question hector exploration error msgs

Hi, All,

A while ago I asked a question on using move base and hector exploration together here. Now, I get some error messages when I run SLAM, hector exploration, movebase together

[ INFO] [1385448000.186189169]: Exploration Service called [ INFO] [1385448000.186304532]: [hector_exploration_planner] exploration: starting exploration [ INFO] [1385448000.669314882]: [hector_exploration_planner] exploration: found 4802 frontiers! [ WARN] [1385448000.799343886]: [hector_exploration_planner] No path to the goal could be found by following gradient! [ INFO] [1385448000.799741182]: [hector_exploration_planner] exploration: could not plan to frontier, starting inner-exploration [ INFO] [1385448000.799854087]: [hector_exploration_planner] inner-exploration: starting exploration [ WARN] [1385448000.952170236]: [hector_exploration_planner] inner-exploration: no inner-frontiers have been found! exploration failed! [INFO] [WallTime: 1385448000.952932] No frontiers left.

The strange thing is that these warnings and error messages only appear when I start my robot, they will remain there as long as the robot is not moving (teleoped, my robot can be teleoped and explore by itself ). Once I teleop my robot for a while (a few seconds), the error messages disappeared and the robot starts to explore by itself. I am really curious what do these messages mean and how can I get rid of them. Thanks!

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2013-11-13 22:49:23 -0500 asked a question display quadrotor yaw/pitch/roll in rviz

Hi guys, I am working on a GUI that shows the yaw/pitch/roll angles of a quadrotor in rviz. I have a few questions: 1) How do I create a customized shape that represents my quadrotor using basic elements such as cube, cylinder, etc? Is it through urdf file? 2) After I created my quadrotor, how to I make it yaw/pitch/roll in rviz, I do have another node that publish yaw/pitch/roll data.

Thanks a lot

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2013-11-12 18:00:51 -0500 commented answer hector exploration with move base

Thanks Stefan. I also noticed that there is a hector_path_follower node in the package and it is used together with the navigation_experimental package. If I were to use these two, do I still need move_base?

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2013-11-11 21:20:44 -0500 asked a question hector exploration with move base

Hi, there,

I am trying out hector exploration on my robot and I have a few questions regarding the configuration. I have used the explore package before and the result is ok. The hector exploration, on the other hand, appears better on paper (though not confirmed). My specific questions are:

In order to use hector exploration, another node need to call the service provided by the hector_exploration_node and feeds the provided goals to move_base. However, when I dig out the hector_exploration_node source code, I don't see a "goal" message published, instead it is the trajectory (hector navigation msg) message. How do I pass this trajectory msg to move base as a goal? Thanks a lot

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2013-09-23 00:27:44 -0500 asked a question Velodyne 32E GPS driver

Hi, All,

I remember there was a discussion on GPS driver of Velodyne 32E sometimes ago. I am just wandering what the status of that driver is. Is there anyone developing this driver? If it is already in progress, how can I contribute?

2013-09-23 00:22:15 -0500 answered a question Setting up ROS network with Velodyne 32e

I was trying to do something similar and even had long discussion with Velodyne engineers. They are still investigating the issue. The conclusion is that home used router/AP might not be able to support large traffic required by the velodyne. Anyway Here is a list of known configuration that will/will not work:

1) Host connected to a wireless router, lidar connected to the same router, client connect to the router wirelessly. Your ROS client will not be able to communicate with host, nor receive velodyne packets.

2) Host, lidar, client are all connected to the router through RJ45 cable. It will work as long as your network setup is correct.

3) Host connected to the lidar through RJ45 cable, then connect to the router wirelessly, client also connect to the router wirelessly. You will loss velodyne packets, but it might "appears" working.

Hope that helps...

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