butterworth_filter.h

Go to the documentation of this file.

/*********************************************************************
 * Software License Agreement (BSD License)
 *
 *  Copyright (c) 2021, PickNik 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 PickNik 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.
 *********************************************************************/
 
/* Author: Andy Zelenak
   Description: A first-order Butterworth low-pass filter. There is only one parameter to tune.
 */
 
#pragma once
 
#include <cstddef>
 
// Auto-generated
#include <moveit_core/moveit_butterworth_parameters.hpp>
#include <moveit/robot_model/robot_model.h>
#include <moveit/online_signal_smoothing/smoothing_base_class.h>
 
namespace online_signal_smoothing
{
class ButterworthFilter
{
public:
  ButterworthFilter(double low_pass_filter_coeff);
  ButterworthFilter() = delete;
 
  double filter(double new_measurement);
 
  void reset(const double data);
 
private:
  static constexpr std::size_t FILTER_LENGTH = 2;
  std::array<double, FILTER_LENGTH> previous_measurements_;
  double previous_filtered_measurement_;
  // Scale and feedback term are calculated from supplied filter coefficient
  double scale_term_;
  double feedback_term_;
};
 
// Plugin
class ButterworthFilterPlugin : public SmoothingBaseClass
{
public:
  bool initialize(rclcpp::Node::SharedPtr node, moveit::core::RobotModelConstPtr robot_model,
                  size_t num_joints) override;
 
  bool doSmoothing(std::vector<double>& position_vector) override;
 
  bool reset(const std::vector<double>& joint_positions) override;
 
private:
  rclcpp::Node::SharedPtr node_;
  std::vector<ButterworthFilter> position_filters_;
  size_t num_joints_;
};
}  // namespace online_signal_smoothing