odom_constraint_node.cpp

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/*
 * Copyright (c) 2008, Willow Garage, Inc.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 *     * Redistributions of source code must retain the above copyright
 *       notice, this list of conditions and the following disclaimer.
 *     * Redistributions in binary form must reproduce the above copyright
 *       notice, this list of conditions and the following disclaimer in the
 *       documentation and/or other materials provided with the distribution.
 *     * Neither the name of the Willow Garage, Inc. nor the names of its
 *       contributors may be used to endorse or promote products derived from
 *       this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 *
 */

#include <pose_graph/diff_subscriber.h>
#include <graph_mapping_utils/utils.h>
#include <graph_mapping_msgs/GraphConstraint.h>
#include <graph_mapping_msgs/ConstraintGraphDiff.h>
#include <ros/ros.h>
#include <boost/optional.hpp>

namespace laser_slam
{

namespace pg=pose_graph;
namespace msg=graph_mapping_msgs;
namespace util=graph_mapping_utils;

using std::string;
using boost::optional;

typedef optional<const msg::ConstraintGraphDiff&> OptionalDiff;

/************************************************************
 * Class
 ***********************************************************/

class OdomConstraints
{
public:
  OdomConstraints (ros::NodeHandle& param_nh);

private:

  tf::Pose fixedFramePose (const ros::Time& t);
  void diffCB (OptionalDiff diff, const pg::ConstraintGraph& g);

  /****************************************
   * Params
   ****************************************/
  
  ros::NodeHandle param_nh_;
  const string base_frame_;
  const string odom_frame_;

  /****************************************
   * State
   ****************************************/
  
  optional<unsigned> last_node_;
  optional<tf::Pose> last_odom_pose_;

  /****************************************
   * Objects
   ****************************************/
  
  ros::NodeHandle nh_;
  tf::TransformListener tf_;
  pg::DiffSubscriber diff_sub_;
  ros::Publisher constraint_pub_;

};

/************************************************************
 * Init
 ***********************************************************/

OdomConstraints::OdomConstraints (ros::NodeHandle& param_nh) :
  param_nh_(param_nh),
  base_frame_(util::getParam<string>(param_nh_, "base_frame")),
  odom_frame_(util::getParam<string>(param_nh_, "fixed_frame")),
  diff_sub_(boost::bind(&OdomConstraints::diffCB, this, _1, _2)),
  constraint_pub_(nh_.advertise<msg::GraphConstraint>("graph_constraints", 10))
{
  ROS_INFO ("odom_constraint_node initialized");
}

/************************************************************
 * Constraints
 ***********************************************************/

tf::Pose OdomConstraints::fixedFramePose (const ros::Time& t) 
{
  tf_.waitForTransform(odom_frame_, base_frame_, t, ros::Duration(1.0));
  tf::StampedTransform tr;
  tf_.lookupTransform(odom_frame_, base_frame_, t, tr);
  return tr;
}

void OdomConstraints::diffCB (OptionalDiff diff,
                              const pg::ConstraintGraph& g)
{
  if (!diff)
  {
    ROS_INFO ("Not adding constraint since got full graph rather than a diff");
  }
  else if (diff->new_nodes.size()!=1)
  {
    ROS_INFO ("Not adding constraint since diff had %zu new nodes",
              diff->new_nodes.size());
  }
  else
  {
    const unsigned n=diff->new_nodes[0].id;
    try
    {
      const tf::Pose odom_pose = fixedFramePose(diff->new_node_timestamps[0]);
      if (last_node_)
      {
        msg::GraphConstraint constraint;
        constraint.src = *last_node_;
        constraint.dest = n;
        constraint.constraint.pose =
          util::toPose(util::relativePose(odom_pose, *last_odom_pose_));
        constraint.constraint.precision =
          util::makePrecisionMatrix(1,1,1,1);
        constraint_pub_.publish(constraint);
        ROS_INFO_STREAM ("Added constraint to " << *last_node_ << 
                         " given new node " << n <<
                         " at " << util::toString(odom_pose));
      }
      else
      {
        ROS_INFO("First node %u seen ", n);
      }

      last_node_ = n;
      last_odom_pose_ = odom_pose;
      ROS_INFO_STREAM ("Last node is now " << *last_node_ << " at "
                       << util::toString(*last_odom_pose_));
    }
    catch (tf::TransformException& e)
    {
      ROS_WARN ("Ignoring new node %u due to tf exception '%s'", n, e.what());
    }
  }
}


} // namespace

int main (int argc, char** argv)
{
  ros::init(argc, argv, "odom_constraint_node");
  ros::NodeHandle param_nh("laser_slam_node");
  laser_slam::OdomConstraints node(param_nh);
  ros::spin();
  return 0;
}

---

laser_slam
Author(s): Bhaskara Marthi
autogenerated on Fri Jan 11 09:53:23 2013