adesh's profile - activity

Hi I am working on Turtlebot in Gazebo environment and have questions about the way velocities and the units worki in gazebo. I know that to take a turn we need to give both linear and angular velocities. If I want to turn the turtlebot through 90 degrees (Pi/2 radians) say in 4 sec, can I give (Pi/8)rad/sec as my angular velocity? I tried controlling angle this way but its not turning the robot in the proportion that I want. Also how does the linear velocity play role here.If any body can explain by some example, (like to turn through w degrees in x secs, linear vel should be y m/sec and angular velocity should be z rad/sec ) it will be a great help. - Thanks Anup

I am trying to use '/gazebo/Model_states' topic to get the model states.

shouldn't the include be like

#include gazebo_msgs/ModelStates.h

and callback function be like

void ModelStatecallback(const gazebo_msgs::ModelStates::ConstPtr& msg)
{
}

Is anything wrong in this ? When I tried this I get following error.

/opt/ros/electric/stacks/ros_comm/clients/cpp/roscpp_traits/include/ros/message_traits.h:121: error: ‘__s_getMD5Sum’ is not a member of ‘int’

/opt/ros/electric/stacks/ros_comm/clients/cpp/roscpp_traits/include/ros/message_traits.h:138: error: ‘__s_getDataType’ is not a member of ‘int'

Any help is appreciated.

Hi I am trying to subscribe and publish at the same time. I tried to follow the suggestions given for similar questions but am not able to publish the data that I am getting using the callback function. My publisher is created in the constructor of a class and is stored in a member variable. I am calling the member.publish method in the callback function. Is this right ? Also, do I need to run the publish command in a dedicated loop again inside the callback function or the looping because of callback function is enough ?

Here is the error message that I get

[FATAL] [1320088082. 162199274] : ASSERTION FAILED file = /opt/ros/electric/stacks/ros_comm/clients/cpp/rospp/include/ros/publisher.h line = 101 cond = false message =

drive_base /usr/include/boost/smart_ptr/shared_ptr.hpp:418: T* boost::shared_ptr< <template-parameter-1-1&gt; &gt;::operator-="">() const [with T = ros::Publisher::Impl]: Assertion `px != 0' failed. Aborted

Can anybody help understand what is going wrong ?

Hi I am using openni_kinect with Diamondback on Ubuntu 10.04. Does anyone know if there is a way to capture just depth data for further analysis ?

From the RGBDSLAM tutorials, after running 'roslaunch rgbdslam kinect+rgbdslam.launch ' I could save point cloud data from the rviz screen as a .ply file (which has x,y,z,r,g,b entries for all points) to see it in something like Meshlab. The problem in this is that the file is really large (10-15 MB) and it is difficult to segregate and analyze just x,y,z data from this.

By the way, what I am trying to do is capture the depth info around at certain frequency and estimate the dynamics of the environment progressively from all the frames captured. Any help is really appreciated

Thanks

Hi, I am trying to run 3d_navigation, (which the ros_wiki says is 'unreleased and contains experimental code').

1. When I am trying to rosinstall, it is giving me following errors.

-ahhhhhhhh, yaml parse error: expected '<document start="">', but found '<scalar>' in "<file>", line 6, column 19. Can anybody tell what might be missing ?

The tutorial says 'Use the following rosinstall to overlay your diamondback installation with the development versions of additional stacks and the 3d_navigation code

- svn:
    uri: https://code.ros.org/svn/wg-ros-pkg/branches/trunk_diamondback/sandbox/3d_navigation/
    local-name: stacks/3d_navigation
- svn:
    uri: https://alufr-ros-pkg.googlecode.com/svn/branches/octomap_mapping-experimental/
    local-name: stacks/octomap_mapping
- svn:
    uri: https://code.ros.org/svn/wg-ros-pkg/stacks/motion_planning_common/branches/arm_navigation_metrics
    local-name: stacks/motion_planning_common

How to use this in a rosinstall command? example please.....

-I tried to use it like:

$ rosinstall /opt/ros/diamonback https:/code.ros.org/svn/wg-ros-pkg/branches/trunk_diamondback/sandbox/3d_navigation/

(as the tutrial says: Usage: rosinstall PATH [URI] [options])

-my opt/ros/diamondback/.rosinstall file looks OK too. Here is its content

- other:
    local-name: /opt/ros/diamondback/ros
- other:
    local-name: /opt/ros/diamondback/stacks

Can anybody help me understand what is going wrong ?

Hi, I am new to the ROS community. why is gazebo GUI crashing when you try simulation tutorial instruction 'roslaunch gazebo_worlds empty_world.launch' ?

The error that I get is

[gazebo-2] process has died [pid 32382, exit code -6]. log files: /home/username/.ros/log/ef5ae1c0-9d25-11e0-99ad-001d0900b3d5/gazebo-2*.log

Any idea ? bdw ..I am using ubuntu 10.04

Thanks in advance.

Hello all I got the issue solved. There was a small mismatch in the 'params' between the source file and the launch file. Thank you.

Yes, I see the position and orientation of the robot in the in_odom topic.

Sorry it was a typing mistake. tf was same as _tf. I have corrected it. I am setting 'odom' as the target frame. In the rxconsole, I can see 'method1Callback Test' which is the implementation of my method1Callback.

Hello all, I am trying to use Message filter just like given in the tutorial 'Using Stamped datatypes with tf::MessageFilter'. for two messages. tf and odom . I also have one more subscriber (which is not synchronized) and has its own callback.

Here is what I am doing:

tf::TransformListener tf;
tf::MessageFilter<nav_msgs::Odometry> * tf_filter;
message_filters::Subscriber<nav_msgs::Odometry> odom_sub;
//initialisation
method1_sub = nh_.subscribe( "topic1",1,&ClassA::method1Callback, this);
odom_sub.subscribe(nh_, "in_odom", 10);
tf_filter = new tf::MessageFilter<nav_msgs::Odometry>(odom_sub, tf,target_frame, 10);
tf_filter->registerCallback( boost::bind(&ClassA::callback_odom, this, _1 ));
//callback
void callback_odom( const nav_msgs::Odometry::ConstPtr& msg )
{
ROS_INFO_STREAM("callback_odom Test");
}

void method1Callback( const geometry_msgs::xyz::ConstPtr& msg )
{
 ROS_INFO_STREAM(" method1Callback Test");
}

But my callback_odom callback function is not getting called;However method1Callback does get called. Does anybody know what might be going wrong? What I want to do is process some data in the 'callback_odom' and then use it further.

Thanks