nkoenig's profile - activity

If you are using the unstable version of gazebo:

<light type="spot" name="spot" cast_shadows="false">
  <origin pose="0 0 3 0 0 0"/>
  <diffuse rgba="0 1 0 1"/>
  <specular rgba=".2 .2 .2 1"/>
  <attenuation range="10" constant="0.2" linear="0.01" quadratic="0.0"/>
  <direction xyz="0 0 -1"/>
  <spot inner_angle="0.1" outer_angle="0.5" falloff="1.2"/>
</light>

if you are using Diamondback or Electric:

<model:renderable name="spot">
  <xyz>0.0 0 3</xyz>
  <static>true</static>

  <light>
    <type>spot</type>
    <direction>0 0 -1</direction>
    <diffuseColor>0.0 0.0 1.0</diffuseColor>
    <specularColor>0.0 0.0 0.1</specularColor>
    <attenuation>.1 0.0 0.0</attenuation>
    <range>5</range>
    <spotCone>8.0 10.0 2.0</spotCone> 
  </light>
</model:renderable>

Work has not begun on NXT in gazebo. What needs to be done is port the NXT meshes to a format readable by Gazebo (Collada or STL are the best), and then write plugins for the various actuators and sensors.

If you want to start work on this, just ask for more help and we can provide you with some more guidance.

Check out this answer: http://answers.ros.org/question/607/rotation-error-in-gazebo-simulation

Ogre has a script to import ogre meshes into blender. Blender can then export collada.

http://www.ogre3d.org/tikiwiki/Tools%3A+Blender#Ogre_Blender_Import_Script

If you are looking for an urdf for a wam arm, then take a look at the arm simulator project http://thearmrobot.com/aboutSimulator.html

Then you can use $ rosrun gazebo gazebo__model -h

To guide you through converting a urdf to gazebo XML format.

Or your can write a launch script to run gazebo with your urdf. Look in gazebo_worlds package for examples.

The documentation in the current version of gazebo is a bit lacking. Example world files is your besst friend.

2) are you trying to calculate the angle at which the wheels slip? If that's the case, then you'll have to write your own controller to look at wheel velocity and model velocity. There is no function to my knowledge in ode that exposes this information.

3) the new gazebo website has more info: gazebo.willowgarage.com

I did a little research into ODE heightfields, and it turns out the collider used for heightfields in ODE is not very efficient: http://groups.google.com/group/ode-users/browse_thread/thread/d883a0e15b1647d5

This has been of the features in Gazebo which has received little use. So, the near term solution is to use triangle meshes, like you have done. It may also be more efficient to break your large terrain into sections. The ODE collision engine uses bounding boxes as a first pass to determine if two object should be checked for collision. So, rather than one large bounding box for the entire terrain mesh, you can have multiple smaller bounding boxes. This will ideally reduce the number of collision checks.

Using a modified camera is definitely a good idea. You should look at the specification of your light sensor, and determine how it behaves in the real world (sensitivity, range, field-of-view, etc).

I would then right a simple shader to attach to the camera (look at the StereoCamera for an example). The shader should fill a texture with light intensity. Right now the StereoCamera has a shader that fills a texture with depth data. You can use this as a starting point, and google should tell you how to compute light intensity in GLSL.

If the above seems overkill, or too much work. Then you can write a sensor that just iterates over all the lights in the world, and computes distance to the sensor. This will have some drawbacks: occlusions and reflections are problematic.

Try these things:

1) Make sure the image type is correct:

$ identify <your_image.png>

The output should look like:

willowMap.png PNG 513x513 513x513+0+0 8-bit PseudoClass 256c 3.41KB 0.000u 0:00.000

2) The location of the willowMap.png that is used by gazebo is:

simulator_gazebo/gazebo/gazebo/share/gazebo/Media/materials/textures

You said that empty_world works. Could you try running other worlds without the PR2? Also try loading the PR2 without the highdef (prosilica) sensor. You can do this by commenting out the appropriate code in the urdf. Go to "pr2_description", and look around for prosilica.

1) you can make things in Gazebo immovable by using the <static> tag. Set this to true in a model, and it won't be movable. Example: <static>true</static>

2) We are working on documentation for creating world files in Gazebo. Currently, the best method is to look at examples in the gazebo sources: roscd gazebo/gazebo/share/gazebo/worlds