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Adding new Nav2 Smoother: Savitzky-Golay Smoother (#3264)
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* initial prototype of the Savitzky Golay Filter Path Smoother

* fixed indexing issue - tested working

* updates for filter

* adding unit tests for SG-filter smoother

* adding lifecycle transitions
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SteveMacenski authored Nov 3, 2022
1 parent c53d432 commit b92ea39
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14 changes: 12 additions & 2 deletions nav2_smoother/CMakeLists.txt
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Expand Up @@ -68,8 +68,18 @@ add_library(simple_smoother SHARED
ament_target_dependencies(simple_smoother
${dependencies}
)

# Savitzky Golay Smoother plugin
add_library(savitzky_golay_smoother SHARED
src/savitzky_golay_smoother.cpp
)
ament_target_dependencies(savitzky_golay_smoother
${dependencies}
)

pluginlib_export_plugin_description_file(nav2_core plugins.xml)


if(BUILD_TESTING)
find_package(ament_lint_auto REQUIRED)
# the following line skips the linter which checks for copyrights
Expand All @@ -82,7 +92,7 @@ endif()
rclcpp_components_register_nodes(${library_name} "nav2_smoother::SmootherServer")

install(
TARGETS ${library_name} simple_smoother
TARGETS ${library_name} simple_smoother savitzky_golay_smoother
ARCHIVE DESTINATION lib
LIBRARY DESTINATION lib
RUNTIME DESTINATION bin
Expand All @@ -104,6 +114,6 @@ if(BUILD_TESTING)
endif()

ament_export_include_directories(include)
ament_export_libraries(${library_name} simple_smoother)
ament_export_libraries(${library_name} simple_smoother savitzky_golay_smoother)
ament_export_dependencies(${dependencies})
ament_package()
2 changes: 2 additions & 0 deletions nav2_smoother/README.md
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Expand Up @@ -7,3 +7,5 @@ A smoothing module implementing the `nav2_behavior_tree::SmoothPath` interface i
See the [Navigation Plugin list](https://navigation.ros.org/plugins/index.html) for a list of the currently known and available smoother plugins.

See its [Configuration Guide Page](https://navigation.ros.org/configuration/packages/configuring-smoother-server.html) for additional parameter descriptions.

This package contains the Simple Smoother and Savitzky-Golay Smoother plugins.
108 changes: 108 additions & 0 deletions nav2_smoother/include/nav2_smoother/savitzky_golay_smoother.hpp
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@@ -0,0 +1,108 @@
// Copyright (c) 2022, Samsung Research America
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License. Reserved.

#ifndef NAV2_SMOOTHER__SAVITZKY_GOLAY_SMOOTHER_HPP_
#define NAV2_SMOOTHER__SAVITZKY_GOLAY_SMOOTHER_HPP_

#include <cmath>
#include <vector>
#include <string>
#include <iostream>
#include <memory>
#include <queue>
#include <utility>

#include "nav2_core/smoother.hpp"
#include "nav2_smoother/smoother_utils.hpp"
#include "nav2_costmap_2d/costmap_2d.hpp"
#include "nav2_costmap_2d/cost_values.hpp"
#include "nav2_util/geometry_utils.hpp"
#include "nav2_util/node_utils.hpp"
#include "nav_msgs/msg/path.hpp"
#include "angles/angles.h"
#include "tf2/utils.h"

namespace nav2_smoother
{

/**
* @class nav2_smoother::SavitzkyGolaySmoother
* @brief A path smoother implementation using Savitzky Golay filters
*/
class SavitzkyGolaySmoother : public nav2_core::Smoother
{
public:
/**
* @brief A constructor for nav2_smoother::SavitzkyGolaySmoother
*/
SavitzkyGolaySmoother() = default;

/**
* @brief A destructor for nav2_smoother::SavitzkyGolaySmoother
*/
~SavitzkyGolaySmoother() override = default;

void configure(
const rclcpp_lifecycle::LifecycleNode::WeakPtr &,
std::string name, std::shared_ptr<tf2_ros::Buffer>,
std::shared_ptr<nav2_costmap_2d::CostmapSubscriber>,
std::shared_ptr<nav2_costmap_2d::FootprintSubscriber>) override;

/**
* @brief Method to cleanup resources.
*/
void cleanup() override {}

/**
* @brief Method to activate smoother and any threads involved in execution.
*/
void activate() override {}

/**
* @brief Method to deactivate smoother and any threads involved in execution.
*/
void deactivate() override {}

/**
* @brief Method to smooth given path
*
* @param path In-out path to be smoothed
* @param max_time Maximum duration smoothing should take
* @return If smoothing was completed (true) or interrupted by time limit (false)
*/
bool smooth(
nav_msgs::msg::Path & path,
const rclcpp::Duration & max_time) override;

protected:
/**
* @brief Smoother method - does the smoothing on a segment
* @param path Reference to path
* @param reversing_segment Return if this is a reversing segment
* @param costmap Pointer to minimal costmap
* @param max_time Maximum time to compute, stop early if over limit
* @return If smoothing was successful
*/
bool smoothImpl(
nav_msgs::msg::Path & path,
bool & reversing_segment);

bool do_refinement_;
int refinement_num_;
rclcpp::Logger logger_{rclcpp::get_logger("SGSmoother")};
};

} // namespace nav2_smoother

#endif // NAV2_SMOOTHER__SAVITZKY_GOLAY_SMOOTHER_HPP_
31 changes: 1 addition & 30 deletions nav2_smoother/include/nav2_smoother/simple_smoother.hpp
Original file line number Diff line number Diff line change
Expand Up @@ -24,6 +24,7 @@
#include <utility>

#include "nav2_core/smoother.hpp"
#include "nav2_smoother/smoother_utils.hpp"
#include "nav2_costmap_2d/costmap_2d.hpp"
#include "nav2_costmap_2d/cost_values.hpp"
#include "nav2_util/geometry_utils.hpp"
Expand All @@ -35,19 +36,6 @@
namespace nav2_smoother
{

/**
* @class nav2_smoother::PathSegment
* @brief A segment of a path in start/end indices
*/
struct PathSegment
{
unsigned int start;
unsigned int end;
};

typedef std::vector<geometry_msgs::msg::PoseStamped>::iterator PathIterator;
typedef std::vector<geometry_msgs::msg::PoseStamped>::reverse_iterator ReversePathIterator;

/**
* @class nav2_smoother::SimpleSmoother
* @brief A path smoother implementation
Expand Down Expand Up @@ -132,23 +120,6 @@ class SimpleSmoother : public nav2_core::Smoother
geometry_msgs::msg::PoseStamped & msg, const unsigned int dim,
const double & value);

/**
* @brief Finds the starting and end indices of path segments where
* the robot is traveling in the same direction (e.g. forward vs reverse)
* @param path Path in which to look for cusps
* @return Set of index pairs for each segment of the path in a given direction
*/
std::vector<PathSegment> findDirectionalPathSegments(const nav_msgs::msg::Path & path);

/**
* @brief For a given path, update the path point orientations based on smoothing
* @param path Path to approximate the path orientation in
* @param reversing_segment Return if this is a reversing segment
*/
inline void updateApproximatePathOrientations(
nav_msgs::msg::Path & path,
bool & reversing_segment);

double tolerance_, data_w_, smooth_w_;
int max_its_, refinement_ctr_;
bool do_refinement_;
Expand Down
132 changes: 132 additions & 0 deletions nav2_smoother/include/nav2_smoother/smoother_utils.hpp
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@@ -0,0 +1,132 @@
// Copyright (c) 2022, Samsung Research America
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License. Reserved.

#ifndef NAV2_SMOOTHER__SMOOTHER_UTILS_HPP_
#define NAV2_SMOOTHER__SMOOTHER_UTILS_HPP_

#include <cmath>
#include <vector>
#include <string>
#include <iostream>
#include <memory>
#include <queue>
#include <utility>

#include "nav2_core/smoother.hpp"
#include "nav2_costmap_2d/costmap_2d.hpp"
#include "nav2_costmap_2d/cost_values.hpp"
#include "nav2_util/geometry_utils.hpp"
#include "nav2_util/node_utils.hpp"
#include "nav_msgs/msg/path.hpp"
#include "angles/angles.h"
#include "tf2/utils.h"

namespace smoother_utils
{

/**
* @class nav2_smoother::PathSegment
* @brief A segment of a path in start/end indices
*/
struct PathSegment
{
unsigned int start;
unsigned int end;
};

typedef std::vector<geometry_msgs::msg::PoseStamped>::iterator PathIterator;
typedef std::vector<geometry_msgs::msg::PoseStamped>::reverse_iterator ReversePathIterator;

inline std::vector<PathSegment> findDirectionalPathSegments(
const nav_msgs::msg::Path & path)
{
std::vector<PathSegment> segments;
PathSegment curr_segment;
curr_segment.start = 0;

// Iterating through the path to determine the position of the cusp
for (unsigned int idx = 1; idx < path.poses.size() - 1; ++idx) {
// We have two vectors for the dot product OA and AB. Determining the vectors.
double oa_x = path.poses[idx].pose.position.x -
path.poses[idx - 1].pose.position.x;
double oa_y = path.poses[idx].pose.position.y -
path.poses[idx - 1].pose.position.y;
double ab_x = path.poses[idx + 1].pose.position.x -
path.poses[idx].pose.position.x;
double ab_y = path.poses[idx + 1].pose.position.y -
path.poses[idx].pose.position.y;

// Checking for the existance of cusp, in the path, using the dot product.
double dot_product = (oa_x * ab_x) + (oa_y * ab_y);
if (dot_product < 0.0) {
curr_segment.end = idx;
segments.push_back(curr_segment);
curr_segment.start = idx;
}

// Checking for the existance of a differential rotation in place.
double cur_theta = tf2::getYaw(path.poses[idx].pose.orientation);
double next_theta = tf2::getYaw(path.poses[idx + 1].pose.orientation);
double dtheta = angles::shortest_angular_distance(cur_theta, next_theta);
if (fabs(ab_x) < 1e-4 && fabs(ab_y) < 1e-4 && fabs(dtheta) > 1e-4) {
curr_segment.end = idx;
segments.push_back(curr_segment);
curr_segment.start = idx;
}
}

curr_segment.end = path.poses.size() - 1;
segments.push_back(curr_segment);
return segments;
}

inline void updateApproximatePathOrientations(
nav_msgs::msg::Path & path,
bool & reversing_segment)
{
double dx, dy, theta, pt_yaw;
reversing_segment = false;

// Find if this path segment is in reverse
dx = path.poses[2].pose.position.x - path.poses[1].pose.position.x;
dy = path.poses[2].pose.position.y - path.poses[1].pose.position.y;
theta = atan2(dy, dx);
pt_yaw = tf2::getYaw(path.poses[1].pose.orientation);
if (fabs(angles::shortest_angular_distance(pt_yaw, theta)) > M_PI_2) {
reversing_segment = true;
}

// Find the angle relative the path position vectors
for (unsigned int i = 0; i != path.poses.size() - 1; i++) {
dx = path.poses[i + 1].pose.position.x - path.poses[i].pose.position.x;
dy = path.poses[i + 1].pose.position.y - path.poses[i].pose.position.y;
theta = atan2(dy, dx);

// If points are overlapping, pass
if (fabs(dx) < 1e-4 && fabs(dy) < 1e-4) {
continue;
}

// Flip the angle if this path segment is in reverse
if (reversing_segment) {
theta += M_PI; // orientationAroundZAxis will normalize
}

path.poses[i].pose.orientation = nav2_util::geometry_utils::orientationAroundZAxis(theta);
}
}

} // namespace smoother_utils

#endif // NAV2_SMOOTHER__SMOOTHER_UTILS_HPP_
6 changes: 6 additions & 0 deletions nav2_smoother/plugins.xml
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Expand Up @@ -4,4 +4,10 @@
<description>Does a simple smoothing process with collision checking</description>
</class>
</library>

<library path="savitzky_golay_smoother">
<class type="nav2_smoother::SavitzkyGolaySmoother" base_class_type="nav2_core::Smoother">
<description>Does Savitzky-Golay smoothing</description>
</class>
</library>
</class_libraries>
1 change: 1 addition & 0 deletions nav2_smoother/src/nav2_smoother.cpp
Original file line number Diff line number Diff line change
@@ -1,5 +1,6 @@
// Copyright (c) 2019 RoboTech Vision
// Copyright (c) 2019 Intel Corporation
// Copyright (c) 2022 Samsung Research America
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
Expand Down
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