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2016-06-28 22:17:21 -0500 marked best answer Conversion between world and occupancy grid msg

Hi all,

I have a map of the environment my robot has to move in. The map is stored in the standard way as an occupancy grid map and served via map_server service. I want to implement a PRM on top of this map so I need to access the value of the occupancy grid from the world coordinate. To be more precise, given a point in the map frame (say [x0,y0]), I need to access the value of the occupancy grid of [x0,y0], that is, I need a conversion from the world coordinate to the index of the vector that represents the occupancy grid.

Do I have to implement everything from scratch or there are already some api that perform this conversion?

Regards

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2016-02-04 18:25:00 -0500 asked a question Replanning using move_base

Hi all,

in the documentation page of move_base, it is reported that the parameter planner_frequency set "The rate in Hz at which to run the global planning loop. If the frequency is set to 0.0, the global planner will only run when a new goal is received or the local planner reports that its path is blocked."

How can I trigger a planning loop from the local planner?

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2016-01-21 05:55:08 -0500 asked a question sbpl_lattice_planner map resolution

Hi all,

I'm using the sbpl_lattice_planner package and I noticed that whereas it works fine when the map resolution is 0.025 (2.5cm), it always fail to find a solution when the resolution is 0.05 (5cm). So far, I just modified the resolution parameters in the motion primitive generator to have them consistent with the map. It seems that the performance of the planner are affected by the resolution of the map, which shouldn't be the case if the motion primitives are changed accordingly.

Should I modify some other paramters?

Best

2016-01-12 08:26:23 -0500 asked a question nested metapackages

Hi All,

I know that packages can be nested using metapackages so that a metapackage can contain multiple packages. Is it possible to nest metapackages (metapackages within a metapackage).

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2015-02-03 15:52:14 -0500 commented answer move_base - missed desired rate

Thanks David. Actually the update rate was too slow

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2015-01-27 06:23:54 -0500 asked a question move_base - missed desired rate

Hi all,

I have a quite high level question. I'm currently trying to unplug the amcl node from the navigation stack and substitute it with a custom localization algorithm. Although I'm able to broadcast the transformation /map -> /odom with a high frequency (40Hz), I'm getting lots of errors such as

[ WARN] [1422360986.992858074, 13.073000000]: Control loop missed its desired rate of 10.0000Hz... the loop actually  took 0.8180 seconds

[ WARN] [1422360986.993048443, 13.073000000]: Map update loop missed its desired rate of 5.0000Hz... the loop actually  took 0.7770 seconds

as well as

[ERROR] [1422360988.321754058, 14.389000000]: Extrapolation Error: Lookup would require extrapolation into the future.  Requested time 13.881000000 but the latest data is at time 13.871000000, when looking up transform from frame [map] to frame [odom]

I was wondering what can cause such an error. The parameters in move_base are set so that the /amcl is not popping any of those warnings/errors.

Thanks and regards.

2014-11-25 03:03:25 -0500 commented answer costmap_2d::VoxelLayer not clearing

Thanks for your suggestion. I'll try it but I think that the VoxelLayer now treats each observation independently so that clearing and marking are applied to each observation source without affecting the others. Anyway, I can be wrong.

2014-11-20 10:43:12 -0500 answered a question costmap_2d::VoxelLayer not clearing

Hello,

After studying the code of costmap_2d::VoxelLayer I found the reason why.

Apparently, the clearing strategy implemented in the VoxelLayer works fine, however, when the points in the clouds that don't lie in the range min/max_obstacle_range are removed from the observation set so, for instance, if you set a min_obstacle_height to filter the floor, the observation of the floor are removed and no clearing is applied.

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2014-11-18 08:05:48 -0500 asked a question costmap_2d::VoxelLayer not clearing

Hello there,

I'm using the move_base navigation stack. I'm realizing that the costmap_2d::VoxelLayer doesn't seem to clear up the costmap when the data are fed from and rgbd sensor. I'm using the following costmap configuration (I omit the local_costmap and global_costmap parameters, I report only the common parameters)

robot_radius: 0.16
plugins:
  - {name: static_layer, type: 'costmap_2d::StaticLayer'}
  - {name: obstacles_layer, type: "costmap_2d::VoxelLayer"}
  - {name: inflation_layer, type: "costmap_2d::InflationLayer"}

obstacles_layer:
  obstacle_range: 1.5
  raytrace_range: 3.0
  observation_sources: rgbd_scan laser_scan 
  rgbd_scan: {sensor_frame: camera_rgb_optical_frame, data_type: PointCloud2, topic: rgbdscan, marking: true, clearing: true, min_obstacle_height: 0.03, max_obstacle_height: 1.00, mark_threshold: 3}
  laser_scan: {sensor_frame: laser_link, data_type: LaserScan, topic: scan, marking: true, clearing: true} 

inflation_layer: 
  inflation_radius: 0.7
  cost_scaling_factor: 20.0

Clearing doesn't work!

Regards, Federico

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2014-11-05 10:26:27 -0500 commented answer Problem with subscriber within costmap layer

Probably you're looking the wrong branch. pedestrian-layer should be the right branch to check.

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2014-11-04 07:37:17 -0500 commented answer Problem with subscriber within costmap layer

As far as I remember, the solution I found was to run the node with the publisher first. Once the topic is published, run the move_base node (eventually with your plugin). Take a look at my github account (federico-b), the pedestrian_layer repository, there should still be the whole source code.

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