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StampedTransform getting Position instead of Relative Position

asked 2015-01-30 11:43:26 -0500

choog gravatar image

HI, I am trying to log some data. The code works like intended except I am receiving the Relative Position instead of the Position.

tf::StampedTransform transformOdom;
current_time = ros::Time::now();

try {
        listener.waitForTransform( "odom","base_footprint", ros::Time(0), ros::Duration(10.0));
    listener.lookupTransform( "odom", "base_footprint",ros::Time(0), transformOdom);
    }
    catch (tf::TransformException &ex) {
        ROS_ERROR("%s",ex.what());
    }

//For debugging purposes
ROS_INFO_STREAM("X pose " <<  transformOdom.getOrigin().x() );
ROS_INFO_STREAM("Y pose " << transformOdom.getOrigin().y());

fileToWrite.open ("log.txt", ios_base::app);
fileToWrite << "X: " << transformOdom.getOrigin().x() << " Y: " << transformOdom.getOrigin().y()<< "\n";
fileToWrite.close();

Here is where you can see the two different positions from the visualization software

Does anyone know how to get the position of the robot instead of the relative position?

Thanks, choog

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answered 2015-01-30 11:47:34 -0500

dornhege gravatar image

You need to choose a frame that you consider fixed, e.g., /map.

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listener.waitForTransform( "map","base_footprint", ros::Time(0), ros::Duration(10.0)); listener.lookupTransform( "map", "base_footprint",ros::Time(0), transformOdom);

as such?

choog gravatar imagechoog ( 2015-01-30 11:50:37 -0500 )edit

That worked. I figured that is what you meant and it tried. Thanks a lot.

choog gravatar imagechoog ( 2015-01-30 11:55:42 -0500 )edit

Hi! I met the same problem just like you, I changed "odom" with "map", instead, I got this error "map" passed to lookupTransform argument target_frame does not exist. Can you tell me what should I do ? I don't even know what odom means. CuzI just started to learn ROS ;(,Thx anyway

Henschel.X gravatar imageHenschel.X ( 2016-03-21 20:48:08 -0500 )edit

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Asked: 2015-01-30 11:43:26 -0500

Seen: 638 times

Last updated: Jan 30 '15