badrobit's profile - activity

I am currently working on trying to create some form of wheel odometry to be used in our system to help determine the pose of our robot. There are no encoders on the wheels but the motor that is used to drive the wheels does report its RPM. I am wondering if there is anyway to use this as an input to the robot_localization node?

I am trying to validate this basic URDF file:

<?xml version="1.0"?>
<robot xmlns:xacro="http://ros.org/wiki/xacro" name="rover">
</robot>

When using XML Copy Editor I am able to have it pass the well-formed check but when I try to validate it I get the following error:

Error at line 2, column 65: no declaration found for element 'robot'

Is there something anyone can see in this basic URDF file that is invalid or why it is unable to find the element for robot?

I am currently working with PCL and a 360-degree point scanner to create maps. I am currently trying to localize them using PCL's ICP to attempt to register the scans. The scans were taken roughly 15 - 20 meters apart but I am getting transforms that look like this from the pcl::GeneralizedIterativeClosestPoint

The point clouds being aligned are created by aligning a series of scans from a spinning lidar while the robot sits still.

Transform Code:

pcl::GeneralizedIterativeClosestPoint< PointT, PointT > icp;
icp.setTransformationEpsilon( 0.00001 );
icp.setMaxCorrespondenceDistance( 1.0 );
icp.setMaximumIterations( 10 );          
icp.setRANSACIterations(10);              
icp.setMaximumOptimizerIterations( 20 ); 

icp.setInputSource(i_query);
icp.setInputTarget(i_reference);

PointCloud temp;
icp.align( temp );

Transform:

0.999574 0.0244488 -0.015959 -0.0191285
-0.0247078 0.999563 -0.0162421 0.0443592
0.015555 0.0166295 0.999741 0.12248
0 0 0 1

This doesn't look right to me as I would expect a much larger offset in the x and y components of the transform. Any suggestions would be appreciated.

I am writing an RQT plugin and when I attempt to build it there are no warnings but when the system attempts to load the plugin I get the following output:

It seems like it is missing the QWidget in the python_qt_binding

 RosPluginProvider.load(juno_safe_button/juno_safe_button) exception raised in __builtin__.__import__(juno_safe_button.juno_safe_button, [JunoSafeButton]):
Traceback (most recent call last):
  File "/opt/ros/kinetic/lib/python2.7/dist-packages/rqt_gui/ros_plugin_provider.py", line 77, in load
    module = __builtin__.__import__(attributes['module_name'], fromlist=[attributes['class_from_class_type']], level=0)
  File "/home/mroscoe/juno_ws/install/lib/python2.7/dist-packages/juno_safe_button/juno_safe_button.py", line 7, in <module>
    from python_qt_binding.QtGui import QWidget
ImportError: cannot import name QWidget

PluginManager._load_plugin() could not load plugin "juno_safe_button/juno_safe_button":
Traceback (most recent call last):
  File "/opt/ros/kinetic/lib/python2.7/dist-packages/qt_gui/plugin_handler.py", line 99, in load
    self._load()
  File "/opt/ros/kinetic/lib/python2.7/dist-packages/qt_gui/plugin_handler_direct.py", line 54, in _load
    self._plugin = self._plugin_provider.load(self._instance_id.plugin_id, self._context)
  File "/opt/ros/kinetic/lib/python2.7/dist-packages/qt_gui/composite_plugin_provider.py", line 71, in load
    instance = plugin_provider.load(plugin_id, plugin_context)
  File "/opt/ros/kinetic/lib/python2.7/dist-packages/qt_gui/composite_plugin_provider.py", line 71, in load
    instance = plugin_provider.load(plugin_id, plugin_context)
  File "/opt/ros/kinetic/lib/python2.7/dist-packages/rqt_gui_py/ros_py_plugin_provider.py", line 60, in load
    return super(RosPyPluginProvider, self).load(plugin_id, plugin_context)
  File "/opt/ros/kinetic/lib/python2.7/dist-packages/qt_gui/composite_plugin_provider.py", line 71, in load
    instance = plugin_provider.load(plugin_id, plugin_context)
  File "/opt/ros/kinetic/lib/python2.7/dist-packages/rqt_gui/ros_plugin_provider.py", line 83, in load
    raise e
ImportError: cannot import name QWidget

I am looking to determine how to compute odometry for my robot. It is a skid-steer platform with one motor on each side (left/right) and each side reports an RPM which is then turned into a velocity.

I have not been able to find any examples of how to use these two velocities to computer the linear and angular components of the twist portion of my odometry message. I have found a way to compute the change in x & y given an angle theta as shown in the RobotSetup/Odom tutorial but I don't know how to get to the theta value.

Any help would be appreciated!