segway_rmp400_odom_6dex_alg_node.cpp

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#include "segway_rmp400_odom_6dex_alg_node.h"

SegwayRmp400OdomAlgNode::SegwayRmp400OdomAlgNode(void) :
  algorithm_base::IriBaseAlgorithm<SegwayRmp400OdomAlgorithm>()
{
  //init class attributes if necessary
  loop_rate_ = 100;//in [Hz]

  public_node_handle_.param<std::string>("tf_prefix",    tf_prefix_,    "");
  public_node_handle_.param<std::string>("odom_id",      odom_id_,      "odom" );
  public_node_handle_.param<std::string>("base_link_id", base_link_id_, "base_footprint" );
  public_node_handle_.param<bool>       ("publish_tf",   publish_tf_,   true  );
  
  // push down frame ids if necessary
  if( tf_prefix_.size()!=0 )
  {
    odom_id_      = tf_prefix_ + "/" + odom_id_;
    base_link_id_ = tf_prefix_ + "/" + base_link_id_;
  }

  accum_.translation.x=0.0; accum_.translation.y=0.0; accum_.translation.z=0.0;
  accum_.rotation.x=0.0; accum_.rotation.y=0.0; accum_.rotation.z=0.0; accum_.rotation.w=1.0;

  H.setIdentity();
  ROS_DEBUG("odo3d Hinit: %f %f %f %f", H(0,0), H(0,1), H(0,2), H(0,3));
  ROS_DEBUG("         %f %f %f %f", H(1,0), H(1,1), H(1,2), H(1,3));
  ROS_DEBUG("         %f %f %f %f", H(2,0), H(2,1), H(2,2), H(2,3));
  ROS_DEBUG("         %f %f %f %f", H(3,0), H(3,1), H(3,2), H(3,3));

  // [init publishers]
  odom_publisher_ = public_node_handle_.advertise<nav_msgs::Odometry>("odom", 100);
  
  // [init subscribers]
  segway_status_subscriber_ = public_node_handle_.subscribe("segway_status", 100, &SegwayRmp400OdomAlgNode::segway_status_callback, this);
  
  // [init services]
  
  // [init clients]
  
  // [init action servers]
  
  // [init action clients]
}

SegwayRmp400OdomAlgNode::~SegwayRmp400OdomAlgNode(void)
{
  // [free dynamic memory]
}

void SegwayRmp400OdomAlgNode::mainNodeThread(void)
{
  ros::Time current_time = ros::Time::now();
  geometry_msgs::TransformStamped odom_trans_msg;
  static ros::Time last_time = ros::Time::now();

  //compute differencial
  double dt = (current_time - last_time).toSec();
  // only if dt is less than one second...
  if(dt<1.0) {

    // 3. Form the rotational velocity vector in local coords
    segway_status_mutex_.enter(); 
    w << roll_rate_, pitch_rate_, yaw_rate_;
    segway_status_mutex_.exit(); 
    ROS_DEBUG("odo3D w: %f %f %f", w(0), w(1), w(2));

    // 4. Compute the local rotation
    wt = w*dt;
    ROS_DEBUG("odo3D wt: %f %f %f", wt(0), wt(1), wt(2));

    // 5. Compute norm of rotation vector
    wt_norm = wt.norm();
    ROS_DEBUG("odo3D wtnorm: %f", wt_norm);

    // 6. Compute the unit norm rotation axis
    ww = wt/wt_norm;
     ROS_DEBUG("odo3D ww: %f %f %f", ww(0), ww(1), ww(2));

    // 7. Build the skew symmetric form of ww
    wt_hat << 0.0, -ww(2), ww(1), ww(2), 0.0, -ww(0), -ww(1), ww(0), 0.0;

    // 8. Build the local velocity vector
    segway_status_mutex_.enter(); 
    v << ((left_wheels_velocity_ + right_wheels_velocity_)/2), 0.0, 0.0;
    segway_status_mutex_.exit(); 
    ROS_DEBUG("odo3D v: %f %f %f", v(0), v(1), v(2));

    // 9. Compute exponential map of twist

    epsilon = 1e-9;

    I.setIdentity();


    if (wt_norm < epsilon) {
      R.setIdentity();
      t =v*dt;
      ROS_DEBUG("odo3D: warning rotation < epsilon!");
    }
    else {
      R = I + wt_hat * sin(wt_norm) + wt_hat*wt_hat*(1-cos(wt_norm));
      // t = (I-R)*wt_hat*v  +  ww.transpose()*v*ww*wt_norm;
      //t = (I-R)*wt_hat*v  +  (ww(0)*v(0)+ww(1)*v(1)+ww(2)*v(2))*ww*wt_norm;
      ta=(I-R)*wt_hat*v*dt/wt_norm ;
      tb= (ww(0)*v(0)+ww(1)*v(1)+ww(2)*v(2))*ww*dt;
      t = ta+tb;
      ROS_DEBUG("odo3D: warning rotation > epsilon: t = %f %f %f + %f %f %f",ta(0),ta(1),ta(2),tb(0),tb(1),tb(2));
    }

    ROS_DEBUG("odo3d R: %f %f %f", R(0,0), R(0,1), R(0,2));
    ROS_DEBUG("         %f %f %f", R(1,0), R(1,1), R(1,2));
    ROS_DEBUG("         %f %f %f", R(2,0), R(2,1), R(2,2));
    ROS_DEBUG("odo3D t: %f %f %f", t(0), t(1), t(2));

    g.setIdentity();
    g.block<3,3>(0,0) = R;
    g.block<3,1>(0,3) = t;

    H = H*g;

    ROS_DEBUG("odo3d H: %f %f %f", H(0,0), H(0,1), H(0,2));
    ROS_DEBUG("         %f %f %f", H(1,0), H(1,1), H(1,2));
    ROS_DEBUG("         %f %f %f", H(2,0), H(2,1), H(2,2));

    d(0) = 1 + H(0,0) - H(1,1) - H(2,2);
    d(1) = 1 - H(0,0) + H(1,1) - H(2,2);
    d(2) = 1 - H(0,0) - H(1,1) + H(2,2);
    d(3) = 1 + H(0,0) + H(1,1) + H(2,2);

    int i;
    d.maxCoeff(&i);

    switch (i) {
      case 0:
          q(0) = sqrt(d(0))/2;
          q(1) = (H(1,0) + H(0,1)) / (4 * q(0));
          q(2) = (H(2,0) + H(0,2)) / (4 * q(0));
          q(3) = (H(2,1) - H(1,2)) / (4 * q(0));
      break;
      case 1:
          q(1) = sqrt(d(1))/2;
          q(0) = (H(1,0) + H(0,1)) / (4 * q(1));
          q(2) = (H(2,1) + H(1,2)) / (4 * q(1));
          q(3) = (H(0,2) - H(2,0)) / (4 * q(1));
      break;
      case 2:
          q(2) = sqrt(d(2))/2;
          q(0) = (H(2,0) + H(0,2)) / (4 * q(2));
          q(1) = (H(2,1) + H(1,2)) / (4 * q(2));
          q(3) = (H(1,0) - H(0,1)) / (4 * q(2));
      break;
      case 3:
          q(3)= sqrt(d(3))/2;
          q(0) = (H(2,1) - H(1,2)) / (4 * q(3));
          q(1) = (H(0,2) - H(2,0)) / (4 * q(3));
          q(2) = (H(1,0) - H(0,1)) / (4 * q(3));
      break;
      default:
          ROS_ERROR("Error computing quaternion");
    }

    ROS_DEBUG("odo3D q: %f %f %f %f", q(0), q(1), q(2), q(3));



    // [fill msg structures]
    accum_.translation.x = H(0,3);
    accum_.translation.y = H(1,3);
    accum_.translation.z = H(2,3);
    accum_.rotation.x = q(0);
    accum_.rotation.y = q(1);
    accum_.rotation.z = q(2);
    accum_.rotation.w = q(3);

    transform_.translation =   accum_.translation;
    transform_.rotation       = accum_.rotation;

    pose_.pose.position.x = accum_.translation.x;
    pose_.pose.position.y = accum_.translation.y;
    pose_.pose.position.z  = accum_.translation.z;
    pose_.pose.orientation = accum_.rotation;
    pose_.covariance[0]  =
    pose_.covariance[7]  = 0.01;
    pose_.covariance[14] =
    pose_.covariance[21] =
    pose_.covariance[28] =
    pose_.covariance[35] = 1e10;

    // Fill the twist with the current translational and rotational velocities
    // in the child coordinate frame (local)

    twist_.twist.linear.x  = v(0);
    twist_.twist.linear.y  = 0.0;
    twist_.twist.linear.z  = 0.0;
    twist_.twist.angular.x = w(0);
    twist_.twist.angular.y = w(1);
    twist_.twist.angular.z = w(2);

    // Add the covariances to use with EKF
    // for x velocity , Error ~= +-5%
    twist_.covariance[0]  = 0.0001;//pow(0.0001*vT,2);
    twist_.covariance[7]  = 0.0001;
    twist_.covariance[14] =
    twist_.covariance[21] =
    twist_.covariance[28] =
    // for theta velocity, Error ~= +-90%
    twist_.covariance[35] = 999; //pow(0.9*vyaw,2);
  }

  //update last time
  last_time = current_time;

 //send the transform
  if(publish_tf_)
  {
    //first, we'll publish the transform over tf
    odom_trans_msg.header.stamp    = current_time;
    odom_trans_msg.header.frame_id = odom_id_;
    odom_trans_msg.child_frame_id  = base_link_id_;
    odom_trans_msg.transform       = transform_;

    odom_broadcaster_.sendTransform(odom_trans_msg);
  }

  //next, we'll publish the odometry message over ROS
  Odometry_msg_.header.stamp    = current_time;
  Odometry_msg_.header.frame_id = odom_id_;
  Odometry_msg_.child_frame_id  = base_link_id_;
  Odometry_msg_.pose            = pose_;
  Odometry_msg_.twist           = twist_;

  // [fill msg structures]
  //Odometry_msg_.data = my_var;
  
  // [fill srv structure and make request to the server]
  
  // [fill action structure and make request to the action server]

  // [publish messages]
  odom_publisher_.publish(Odometry_msg_);
}

/*  [subscriber callbacks] */
void SegwayRmp400OdomAlgNode::segway_status_callback(const iri_segway_rmp_msgs::SegwayRMP400Status::ConstPtr& msg) 
{ 
  ROS_DEBUG("SegwayRmp400OdomAlgNode::segway_status_callback: New Message Received"); 

  //use appropiate mutex to shared variables if necessary 
  //alg_.lock(); 
  segway_status_mutex_.enter(); 

  //std::cout << msg->data << std::endl;
  left_wheels_velocity_  = (msg->rmp200[0].left_wheel_velocity  + msg->rmp200[1].left_wheel_velocity)/2;
  right_wheels_velocity_ = (msg->rmp200[0].right_wheel_velocity + msg->rmp200[1].right_wheel_velocity)/2;
  yaw_rate_              = -(msg->rmp200[0].yaw_rate   + msg->rmp200[1].yaw_rate)/2;
  pitch_rate_            = (msg->rmp200[0].pitch_rate + msg->rmp200[1].pitch_rate) / 2;
  roll_rate_             = (msg->rmp200[0].roll_rate  + msg->rmp200[1].roll_rate ) / 2;

  //unlock previously blocked shared variables 
  //alg_.unlock(); 
  segway_status_mutex_.exit(); 
}

/*  [service callbacks] */

/*  [action callbacks] */

/*  [action requests] */

void SegwayRmp400OdomAlgNode::node_config_update(Config &config, uint32_t level)
{
  alg_.lock();

  alg_.unlock();
}

void SegwayRmp400OdomAlgNode::addNodeDiagnostics(void)
{
}

/* main function */
int main(int argc,char *argv[])
{
  return algorithm_base::main<SegwayRmp400OdomAlgNode>(argc, argv, "segway_rmp400_odom_alg_node");
}