Random-I-Am's profile - activity

I have a launchfile in which I want to specify the path to a specific file, e.g. haarcascade_frontalface_alt.xml. Normally, I would just use the <param> tag like this:

<param name="haarcascade_filename" type="string" value="$(env ROS_ROOT)/../OpenCV/haarcascades/haarcascade_frontalface_alt.xml" />

and try to load it during initialization using NodeHandle::param():

ros::NodeHandle local_nh("~");
local_nh.param("haarcascade_filename", name_, std::string(""));

This is the way it is done for example in the face_detector stack. Assume that I now want to specify multiple files using a <rosparam> list:

<rosparam param="haarcascade_filename_list">["$(env ROS_ROOT)/../OpenCV/haarcascades/haarcascade_frontalface_alt.xml", "morestrings.."]</rosparam>

This is the way I'm trying to load all the entries of the list:

    XmlRpc::XmlRpcValue my_xmlrpc_haarlist;
    local_nh.getParam("haarcascade_filename_list", my_xmlrpc_haarlist);
    ROS_ASSERT(my_xmlrpc_haarlist.getType() == XmlRpc::XmlRpcValue::TypeArray);

    for (int32_t i = 0; i < my_xmlrpc_haarlist.size(); ++i) {
        ROS_ASSERT(my_xmlrpc_haarlist[i].getType() == XmlRpc::XmlRpcValue::TypeString);
        haar_filename_list_.push_back(static_cast<std::string> (my_xmlrpc_haarlist[i]));
    }

The problem is if I now do ROS_INFO_STREAM("Filename: " << supername_); and ROS_INFO_STREAM("Filename list: " << haar_filename_list_.at(0)); the results are not the same:

[ INFO] [1354712164.859028413]: Filename: /opt/ros/fuerte/share/ros/../OpenCV/haarcascades/haarcascade_frontalface_alt.xml
[ INFO] [1354712164.859087292]: Filename list: $(env ROS_ROOT)/../OpenCV/haarcascades/haarcascade_frontalface_alt.xml

How do I solve this issue?

I was wondering if there was any way to change the yaw_goal_tolerance and xy_goal_tolerance of e.g. the base_local_planner.

There are several situations where we want to apply a very small tolerance (+decrease accs and vels). But since this should definitely not be the default we want to be capable of 'dynamically reconfigure' those params. Unfortunately, those parameters are missing from the according reconfigure message.

What recently came to my mind was killing and restarting the node and apply a different set of default parameters. In my opinion, that would be a really dirty hack though.

What I ended up doing was to write a LaserFilter plugin which increased the timestamp of the LaserData frames by 200ms. This resolves all the issues I described above!

This is a general problem but espacially painful while rotating. The most problematic result of this is when the LaserData are creating obstacles while rotating, since those might not be removed because the robot now looks to e.g. the opposite direction. I'll look into the timestamp issue!

I recently stumbled upon a strange behavior my robot is showing while rotating. Now, when it rotates I am capable of observing two strange things (visualized using rviz).

• LaserData is always displayed slightly delayed. Meaning, the RobotFootprint is refreshed quick (almost real-time) while the LaserData is not.
• When the rotation of the robot stops the rotation of the visualized RobotFootprint is stopping as well. Unfortunately this is not the case with the LaserData. LaserData will continue to follow the rotation for at least a few frames and then suddenly jump back matching the end pose.

While on first sight this might just seem to be some kind of visualization problem it really affects path planning. For a better understanding assume the robot stands in front of an opened door and rotates to the left. The laser scans representing the right side of the door frame keep moving to the left. In the end they are right in the middle of the door yielding obstacles preventing my robot to plan any path through that door.

The only issue that came to my mind that could lead to such a behavior is the following:

• Some problem with publishing frequencies

Any suggestion is appreciated. I will update my question as soon as someone comes up with any idea and post additional information.

(Our Kinect PointCloud is fine. No delay, no jumps in between two frames)

I tried the second approach before but couldn't get the subscriber to work (for whatever reasons). I did it again and it seems to work now. A different approach seems to send a Reconfigure object with an empty request. The response will then contain the current configuration as a response. Feedback?

Lets say I just created a piece of software which is capable of sending dynamic_reconfigure configs towards the /move_base/local_costmap/set_parameter server.

The only way to send a configuration is to send the whole configuration and therefore one needs to send the values of each member of the configuration object. Since my design allows for manipulating only single or few parameters I need to retrieve the current values of all the other members so they are not set to their datatypes default values.

What I found so far is the following:

• Use the response of the dynamic_reconfigure call (won't help, since that leads to the same problem of creating the first configuration which I would send to get the response)
• Various topics including /move_base/local_costmap/parameter_(descriptions||update) (won't help for the same reason)

Obviously, my question now is how to get a configuration object holding the current values of the server.