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Extract robot position from rosbag

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I recorded tf-messages (while driving the robot) into a bagfile and wrote a ros node that should extract the positions (base_link-frame) from that bag file. My idea was to use a tf::Transformer and feed it with all the transforms stored in the tf-messages: rosbag::Bag bag; bag.open("tf.bag", rosbag::bagmode::Read); std::vector topics; topics.push_back("/tf"); rosbag::View view(bag, rosbag::TopicQuery(topics)); tf::Transformer transformer; BOOST_FOREACH(rosbag::MessageInstance const m, view) { //instantiate bag message tf::tfMessage::ConstPtr tfPtr = m.instantiate(); BOOST_FOREACH(geometry_msgs::TransformStamped const tfs, tfPtr->transforms) { tf::StampedTransform stampedTf; tf::transformStampedMsgToTF(tfs, stampedTf); //setTransform returns true! transformer.setTransform(stampedTf); ... } } The method setTransform(...) always returns true, so I thought that it works... Each time I get a transform with child_frame == /robot_1/base_link I want to get the map-base_link-transform at the time of this last transform. But the transformer returns false: if(transformer.canTransform(baseLink, mapFrame, stampedTf.stamp_)==true){ //lookup transform transformer.lookupTransform(baseLink, mapFrame, stampedTf.stamp_, temp); } A few additional facts: The transformer's latest common time is always = 0: transformer.getLatestCommonTime(baseLink, mapFrame, time, NULL) And printing all tf-messages of the bag shows that the tf-tree should be consistent (I'm using stage and used view_frames): /map -> /robot_1/odom -> /robot_1/base_footprint -> /robot_1/base_link -> /robot_1/base_laser_link Is something wrong with my code or idea? Any suggestions for a better solution? Thanks in advance!

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