gazebo_ros_kobuki_updates.cpp

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/*
 * Copyright (c) 2013, Yujin Robot.
 * 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 Yujin Robot 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 "kobuki_gazebo_plugins/gazebo_ros_kobuki.h"


namespace gazebo {


void GazeboRosKobuki::updateJointState()
{
  /*
   * Joint states
   */
  std::string baselink_frame = gazebo_ros_->resolveTF("base_link");
  joint_state_.header.stamp = ros::Time::now();
  joint_state_.header.frame_id = baselink_frame;
  joint_state_.position[LEFT] = joints_[LEFT]->GetAngle(0).Radian();
  joint_state_.velocity[LEFT] = joints_[LEFT]->GetVelocity(0);
  joint_state_.position[RIGHT] = joints_[RIGHT]->GetAngle(0).Radian();
  joint_state_.velocity[RIGHT] = joints_[RIGHT]->GetVelocity(0);
  joint_state_pub_.publish(joint_state_);
}

/*
 * Odometry (encoders & IMU)
 */
void GazeboRosKobuki::updateOdometry(common::Time& step_time)
{
  std::string odom_frame = gazebo_ros_->resolveTF("odom");
  std::string base_frame = gazebo_ros_->resolveTF("base_footprint");
  odom_.header.stamp = joint_state_.header.stamp;
  odom_.header.frame_id = odom_frame;
  odom_.child_frame_id = base_frame;

  // Distance travelled by main wheels
  double d1, d2;
  double dr, da;
  d1 = d2 = 0;
  dr = da = 0;
  d1 = step_time.Double() * (wheel_diam_ / 2) * joints_[LEFT]->GetVelocity(0);
  d2 = step_time.Double() * (wheel_diam_ / 2) * joints_[RIGHT]->GetVelocity(0);
  // Can see NaN values here, just zero them out if needed
  if (isnan(d1))
  {
    ROS_WARN_STREAM_THROTTLE(0.1, "Gazebo ROS Kobuki plugin: NaN in d1. Step time: " << step_time.Double()
                             << ", WD: " << wheel_diam_ << ", velocity: " << joints_[LEFT]->GetVelocity(0));
    d1 = 0;
  }
  if (isnan(d2))
  {
    ROS_WARN_STREAM_THROTTLE(0.1, "Gazebo ROS Kobuki plugin: NaN in d2. Step time: " << step_time.Double()
                             << ", WD: " << wheel_diam_ << ", velocity: " << joints_[RIGHT]->GetVelocity(0));
    d2 = 0;
  }
  dr = (d1 + d2) / 2;
  da = (d2 - d1) / wheel_sep_; // ignored

  // Just as in the Kobuki driver, the angular velocity is taken directly from the IMU
  vel_angular_ = imu_->GetAngularVelocity();

  // Compute odometric pose
  odom_pose_[0] += dr * cos( odom_pose_[2] );
  odom_pose_[1] += dr * sin( odom_pose_[2] );
  odom_pose_[2] += vel_angular_.z * step_time.Double();
  // Compute odometric instantaneous velocity
  odom_vel_[0] = dr / step_time.Double();
  odom_vel_[1] = 0.0;
  odom_vel_[2] = vel_angular_.z;

  odom_.pose.pose.position.x = odom_pose_[0];
  odom_.pose.pose.position.y = odom_pose_[1];
  odom_.pose.pose.position.z = 0;

  tf::Quaternion qt;
  qt.setEuler(0,0,odom_pose_[2]);
  odom_.pose.pose.orientation.x = qt.getX();
  odom_.pose.pose.orientation.y = qt.getY();
  odom_.pose.pose.orientation.z = qt.getZ();
  odom_.pose.pose.orientation.w = qt.getW();

  odom_.pose.covariance[0]  = 0.1;
  odom_.pose.covariance[7]  = 0.1;
  odom_.pose.covariance[35] = 0.05;
  odom_.pose.covariance[14] = 1e6;
  odom_.pose.covariance[21] = 1e6;
  odom_.pose.covariance[28] = 1e6;

  odom_.twist.twist.linear.x = odom_vel_[0];
  odom_.twist.twist.linear.y = 0;
  odom_.twist.twist.linear.z = 0;
  odom_.twist.twist.angular.x = 0;
  odom_.twist.twist.angular.y = 0;
  odom_.twist.twist.angular.z = odom_vel_[2];
  odom_pub_.publish(odom_); // publish odom message

  if (publish_tf_)
  {
    odom_tf_.header = odom_.header;
    odom_tf_.child_frame_id = odom_.child_frame_id;
    odom_tf_.transform.translation.x = odom_.pose.pose.position.x;
    odom_tf_.transform.translation.y = odom_.pose.pose.position.y;
    odom_tf_.transform.translation.z = odom_.pose.pose.position.z;
    odom_tf_.transform.rotation = odom_.pose.pose.orientation;
    tf_broadcaster_.sendTransform(odom_tf_);
  }
}

/*
 * Publish IMU data
 */
void GazeboRosKobuki::updateIMU()
{
  imu_msg_.header = joint_state_.header;
  math::Quaternion quat = imu_->GetOrientation();
  imu_msg_.orientation.x = quat.x;
  imu_msg_.orientation.y = quat.y;
  imu_msg_.orientation.z = quat.z;
  imu_msg_.orientation.w = quat.w;
  imu_msg_.orientation_covariance[0] = 1e6;
  imu_msg_.orientation_covariance[4] = 1e6;
  imu_msg_.orientation_covariance[8] = 0.05;
  imu_msg_.angular_velocity.x = vel_angular_.x;
  imu_msg_.angular_velocity.y = vel_angular_.y;
  imu_msg_.angular_velocity.z = vel_angular_.z;
  imu_msg_.angular_velocity_covariance[0] = 1e6;
  imu_msg_.angular_velocity_covariance[4] = 1e6;
  imu_msg_.angular_velocity_covariance[8] = 0.05;
  math::Vector3 lin_acc = imu_->GetLinearAcceleration();
  imu_msg_.linear_acceleration.x = lin_acc.x;
  imu_msg_.linear_acceleration.y = lin_acc.y;
  imu_msg_.linear_acceleration.z = lin_acc.z;
  imu_pub_.publish(imu_msg_); // publish odom message
}

/*
 * Propagate velocity commands
 * TODO: Check how to simulate disabled motors, e.g. set MaxForce to zero, but then damping is important!
 */
void GazeboRosKobuki::propagateVelocityCommands()
{
  if (((prev_update_time_- last_cmd_vel_time_).Double() > cmd_vel_timeout_) || !motors_enabled_)
  {
    wheel_speed_cmd_[LEFT] = 0.0;
    wheel_speed_cmd_[RIGHT] = 0.0;
  }
  joints_[LEFT]->SetVelocity(0, wheel_speed_cmd_[LEFT] / (wheel_diam_ / 2.0));
  joints_[RIGHT]->SetVelocity(0, wheel_speed_cmd_[RIGHT] / (wheel_diam_ / 2.0));
  joints_[LEFT]->SetMaxForce(0, torque_);
  joints_[RIGHT]->SetMaxForce(0, torque_);
}

/*
 * Cliff sensors
 * Check each sensor separately
 */
void GazeboRosKobuki::updateCliffSensor()
{
  // Left cliff sensor
  if ((cliff_detected_left_ == false) &&
      (cliff_sensor_left_->GetRange(0) >= cliff_detection_threshold_))
  {
    cliff_detected_left_ = true;
    cliff_event_.sensor = kobuki_msgs::CliffEvent::LEFT;
    cliff_event_.state = kobuki_msgs::CliffEvent::CLIFF;
    // convert distance back to an AD reading
    cliff_event_.bottom = (int)(76123.0f * atan2(0.995f, cliff_sensor_left_->GetRange(0)));
    cliff_event_pub_.publish(cliff_event_);
  }
  else if ((cliff_detected_left_ == true) &&
            (cliff_sensor_left_->GetRange(0) < cliff_detection_threshold_))
  {
    cliff_detected_left_ = false;
    cliff_event_.sensor = kobuki_msgs::CliffEvent::LEFT;
    cliff_event_.state = kobuki_msgs::CliffEvent::FLOOR;
    // convert distance back to an AD reading
    cliff_event_.bottom = (int)(76123.0f * atan2(0.995f, cliff_sensor_left_->GetRange(0)));
    cliff_event_pub_.publish(cliff_event_);
  }
  // Centre cliff sensor
  if ((cliff_detected_center_ == false) &&
      (cliff_sensor_center_->GetRange(0) >= cliff_detection_threshold_))
  {
    cliff_detected_center_ = true;
    cliff_event_.sensor = kobuki_msgs::CliffEvent::CENTER;
    cliff_event_.state = kobuki_msgs::CliffEvent::CLIFF;
    // convert distance back to an AD reading
    cliff_event_.bottom = (int)(76123.0f * atan2(0.995f, cliff_sensor_center_->GetRange(0)));
    cliff_event_pub_.publish(cliff_event_);
  }
  else if ((cliff_detected_center_ == true) &&
            (cliff_sensor_center_->GetRange(0) < cliff_detection_threshold_))
  {
    cliff_detected_center_ = false;
    cliff_event_.sensor = kobuki_msgs::CliffEvent::CENTER;
    cliff_event_.state = kobuki_msgs::CliffEvent::FLOOR;
    // convert distance back to an AD reading
    cliff_event_.bottom = (int)(76123.0f * atan2(0.995f, cliff_sensor_center_->GetRange(0)));
    cliff_event_pub_.publish(cliff_event_);
  }
  // Right cliff sensor
  if ((cliff_detected_right_ == false) &&
      (cliff_sensor_right_->GetRange(0) >= cliff_detection_threshold_))
  {
    cliff_detected_right_ = true;
    cliff_event_.sensor = kobuki_msgs::CliffEvent::RIGHT;
    cliff_event_.state = kobuki_msgs::CliffEvent::CLIFF;
    // convert distance back to an AD reading
    cliff_event_.bottom = (int)(76123.0f * atan2(0.995f, cliff_sensor_right_->GetRange(0)));
    cliff_event_pub_.publish(cliff_event_);
  }
  else if ((cliff_detected_right_ == true) &&
            (cliff_sensor_right_->GetRange(0) < cliff_detection_threshold_))
  {
    cliff_detected_right_ = false;
    cliff_event_.sensor = kobuki_msgs::CliffEvent::RIGHT;
    cliff_event_.state = kobuki_msgs::CliffEvent::FLOOR;
    // convert distance back to an AD reading
    cliff_event_.bottom = (int)(76123.0f * atan2(0.995f, cliff_sensor_right_->GetRange(0)));
    cliff_event_pub_.publish(cliff_event_);
  }
}

/*
 * Bumpers
 */
// In order to simulate the three bumper sensors, a contact is assigned to one of the bumpers
// depending on its position. Each sensor covers a range of 60 degrees.
// +90 ... +30: left bumper
// +30 ... -30: centre bumper
// -30 ... -90: right bumper
void GazeboRosKobuki::updateBumper()
{
  // reset flags
  bumper_left_is_pressed_ = false;
  bumper_center_is_pressed_ = false;
  bumper_right_is_pressed_ = false;
                                                                                                                        
  // parse contacts
  msgs::Contacts contacts;
  contacts = bumper_->GetContacts();
  math::Pose current_pose = model_->GetWorldPose();
  double robot_heading = current_pose.rot.GetYaw();
                                                                                                                        
  for (int i = 0; i < contacts.contact_size(); ++i)
  {
    double rel_contact_pos =  contacts.contact(i).position(0).z() - current_pose.pos.z;
    // Actually, only contacts at the height of the bumper should be considered, but since we use a simplified collision model
    // contacts further below and above need to be consider as well to identify "bumps" reliably.
    if ((rel_contact_pos >= 0.01)
        && (rel_contact_pos <= 0.13))
    {
      // using the force normals below, since the contact position is given in world coordinates
      // also negating the normal, because it points from contact to robot centre
      double global_contact_angle = std::atan2(-contacts.contact(i).normal(0).y(), -contacts.contact(i).normal(0).x());
      double relative_contact_angle = global_contact_angle - robot_heading;
                                                                                                                        
      if ((relative_contact_angle <= (M_PI/2)) && (relative_contact_angle > (M_PI/6)))
      {
        bumper_left_is_pressed_ = true;
      }
      else if ((relative_contact_angle <= (M_PI/6)) && (relative_contact_angle >= (-M_PI/6)))
      {
        bumper_center_is_pressed_ = true;
      }
      else if ((relative_contact_angle < (-M_PI/6)) && (relative_contact_angle >= (-M_PI/2)))
      {
        bumper_right_is_pressed_ = true;
      }
    }
  }
                                                                                                                        
  // check for bumper state change
  if (bumper_left_is_pressed_ && !bumper_left_was_pressed_)
  {
    bumper_left_was_pressed_ = true;
    bumper_event_.state = kobuki_msgs::BumperEvent::PRESSED;
    bumper_event_.bumper = kobuki_msgs::BumperEvent::LEFT;
    bumper_event_pub_.publish(bumper_event_);
  }
  else if (!bumper_left_is_pressed_ && bumper_left_was_pressed_)
  {
    bumper_left_was_pressed_ = false;
    bumper_event_.state = kobuki_msgs::BumperEvent::RELEASED;
    bumper_event_.bumper = kobuki_msgs::BumperEvent::LEFT;
    bumper_event_pub_.publish(bumper_event_);
  }
  if (bumper_center_is_pressed_ && !bumper_center_was_pressed_)
  {
    bumper_center_was_pressed_ = true;
    bumper_event_.state = kobuki_msgs::BumperEvent::PRESSED;
    bumper_event_.bumper = kobuki_msgs::BumperEvent::CENTER;
    bumper_event_pub_.publish(bumper_event_);
  }
  else if (!bumper_center_is_pressed_ && bumper_center_was_pressed_)
  {
    bumper_center_was_pressed_ = false;
    bumper_event_.state = kobuki_msgs::BumperEvent::RELEASED;
    bumper_event_.bumper = kobuki_msgs::BumperEvent::CENTER;
    bumper_event_pub_.publish(bumper_event_);
  }
  if (bumper_right_is_pressed_ && !bumper_right_was_pressed_)
  {
    bumper_right_was_pressed_ = true;
    bumper_event_.state = kobuki_msgs::BumperEvent::PRESSED;
    bumper_event_.bumper = kobuki_msgs::BumperEvent::RIGHT;
    bumper_event_pub_.publish(bumper_event_);
  }
  else if (!bumper_right_is_pressed_ && bumper_right_was_pressed_)
  {
    bumper_right_was_pressed_ = false;
    bumper_event_.state = kobuki_msgs::BumperEvent::RELEASED;
    bumper_event_.bumper = kobuki_msgs::BumperEvent::RIGHT;
    bumper_event_pub_.publish(bumper_event_);
  }
}
}