odometry.cpp

Go to the documentation of this file.

/*********************************************************************
 * Software License Agreement (BSD License)
 *
 *  Copyright (c) 2013, PAL Robotics, S.L.
 *  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 PAL Robotics 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.
 *********************************************************************/
 
/*
 * Author: Luca Marchionni
 * Author: Bence Magyar
 * Author: Enrique Fernández
 * Author: Paul Mathieu
 * Author: Masaru Morita
 */
 
#include <ackermann_steering_controller/odometry.h>
 
namespace ackermann_steering_controller
{
  namespace bacc = boost::accumulators;
 
  Odometry::Odometry(size_t velocity_rolling_window_size)
  : timestamp_(0.0)
  , x_(0.0)
  , y_(0.0)
  , heading_(0.0)
  , linear_(0.0)
  , angular_(0.0)
  , wheel_separation_h_(0.0)
  , wheel_radius_(0.0)
  , rear_wheel_old_pos_(0.0)
  , velocity_rolling_window_size_(velocity_rolling_window_size)
  , linear_acc_(RollingWindow::window_size = velocity_rolling_window_size)
  , angular_acc_(RollingWindow::window_size = velocity_rolling_window_size)
  , integrate_fun_(std::bind(&Odometry::integrateExact, this, std::placeholders::_1, std::placeholders::_2))
  {
  }
 
  void Odometry::init(const ros::Time& time)
  {
    // Reset accumulators and timestamp:
    resetAccumulators();
    timestamp_ = time;
  }
 
  bool Odometry::update(double rear_wheel_pos, double front_steer_pos, const ros::Time &time)
  {
    const double rear_wheel_cur_pos = rear_wheel_pos * wheel_radius_;
 
    //const double left_wheel_est_vel  = left_wheel_cur_pos  - left_wheel_old_pos_;
    //const double right_wheel_est_vel = right_wheel_cur_pos - right_wheel_old_pos_;
 
    const double rear_wheel_est_vel = rear_wheel_cur_pos - rear_wheel_old_pos_;
 
    rear_wheel_old_pos_ = rear_wheel_cur_pos;
 
    const double linear  = rear_wheel_est_vel;//(right_wheel_est_vel + left_wheel_est_vel) * 0.5;
    //const double angular = (right_wheel_est_vel - left_wheel_est_vel) / wheel_separation_w_;
    const double angular = tan(front_steer_pos) * linear / wheel_separation_h_;
 
    integrate_fun_(linear, angular);
 
    const double dt = (time - timestamp_).toSec();
    if (dt < 0.0001)
      return false; // Interval too small to integrate with
 
    timestamp_ = time;
 
    linear_acc_(linear/dt);
    angular_acc_(angular/dt);
 
    linear_ = bacc::rolling_mean(linear_acc_);
    angular_ = bacc::rolling_mean(angular_acc_);
 
    return true;
  }
 
  void Odometry::updateOpenLoop(double linear, double angular, const ros::Time &time)
  {
    linear_ = linear;
    angular_ = angular;
 
    const double dt = (time - timestamp_).toSec();
    timestamp_ = time;
    integrate_fun_(linear * dt, angular * dt);
  }
 
  void Odometry::setWheelParams(double wheel_separation_h, double wheel_radius)
  {
    wheel_separation_h_ = wheel_separation_h;
    wheel_radius_     = wheel_radius;
  }
 
  void Odometry::setVelocityRollingWindowSize(size_t velocity_rolling_window_size)
  {
    velocity_rolling_window_size_ = velocity_rolling_window_size;
 
    resetAccumulators();
  }
 
  void Odometry::integrateRungeKutta2(double linear, double angular)
  {
    const double direction = heading_ + angular * 0.5;
 
    x_       += linear * cos(direction);
    y_       += linear * sin(direction);
    heading_ += angular;
  }
 
  void Odometry::integrateExact(double linear, double angular)
  {
    if (fabs(angular) < 1e-6)
      integrateRungeKutta2(linear, angular);
    else
    {
      const double heading_old = heading_;
      const double r = linear/angular;
      heading_ += angular;
      x_       +=  r * (sin(heading_) - sin(heading_old));
      y_       += -r * (cos(heading_) - cos(heading_old));
    }
  }
 
  void Odometry::resetAccumulators()
  {
    linear_acc_ = RollingMeanAcc(RollingWindow::window_size = velocity_rolling_window_size_);
    angular_acc_ = RollingMeanAcc(RollingWindow::window_size = velocity_rolling_window_size_);
  }
 
} // namespace diff_drive_controller