Added collision detection for docking (#4752) (#4758)

* Added collision detection for docking

Signed-off-by: Alberto Tudela <ajtudela@gmail.com>

* Minor fixes

Signed-off-by: Alberto Tudela <ajtudela@gmail.com>

* Improve collision  while undocking and test

Signed-off-by: Alberto Tudela <ajtudela@gmail.com>

* Fix smoke testing

Signed-off-by: Alberto Tudela <ajtudela@gmail.com>

* Rename dock_collision_threshold

Signed-off-by: Alberto Tudela <ajtudela@gmail.com>

* Added docs and params

Signed-off-by: Alberto Tudela <ajtudela@gmail.com>

* Minor changes in README

Signed-off-by: Alberto Tudela <ajtudela@gmail.com>

---------

Signed-off-by: Alberto Tudela <ajtudela@gmail.com>
(cherry picked from commit 90a6c8d)

Co-authored-by: Alberto Tudela <ajtudela@gmail.com>

Author: mergify[bot]

nav2_bringup/params/nav2_params.yaml

@@ -421,6 +421,13 @@ docking_server:
       k_delta: 2.0
       v_linear_min: 0.15
       v_linear_max: 0.15
+      use_collision_detection: true
+      costmap_topic: "/local_costmap/costmap_raw"
+      footprint_topic: "/local_costmap/published_footprint"
+      transform_tolerance: 0.1
+      projection_time: 5.0
+      simulation_step: 0.1
+      dock_collision_threshold: 0.3
 
 loopback_simulator:
   ros__parameters:

nav2_docking/README.md

@@ -208,14 +208,21 @@ For debugging purposes, there are several publishers which can be used with RVIZ
 | dock_database  |  The filepath to the dock database to use for this environment | string |  N/A  |
 | docks  |  Instead of `dock_database`, the set of docks specified in the params file itself | vector<string> | N/A     |
 | navigator_bt_xml  | BT XML to use for Navigator, if non-default | string | ""     |
-| controller.k_phi  | TODO | double | 3.0  |
-| controller.k_delta  |  TODO | double | 2.0     |
-| controller.beta  |  TODO | double | 0.4  |
-| controller.lambda  |  TODO | double | 2.0     |
-| controller.v_linear_min  |  TODO | double | 0.1     |
-| controller.v_linear_max |  TODO | double | 0.25    |
-| controller.v_angular_max |  TODO | double | 0.75    |
-| controller.slowdown_radius |  TODO | double | 0.25     |
+| controller.k_phi  | Ratio of the rate of change in phi to the rate of change in r. Controls the convergence of the slow subsystem  | double | 3.0  |
+| controller.k_delta  | Constant factor applied to the heading error feedback. Controls the convergence of the fast subsystem | double | 2.0     |
+| controller.beta  | Constant factor applied to the path curvature. This value must be positive. Determines how fast the velocity drops when the curvature increases | double | 0.4  |
+| controller.lambda  | Constant factor applied to the path curvature. This value must be greater or equal to 1. Determines the sharpness of the curve: higher lambda implies sharper curves | double | 2.0     |
+| controller.v_linear_min | Minimum linear velocity (m/s) | double | 0.1     |
+| controller.v_linear_max | Maximum linear velocity (m/s) | double | 0.25    |
+| controller.v_angular_max | Maximum angular velocity (rad/s) produced by the control law | double | 0.75    |
+| controller.slowdown_radius | Radius (m) around the goal pose in which the robot will start to slow down | double | 0.25     |
+| controller.use_collision_detection | Whether to use collision detection to avoid obstacles | bool | true     |
+| controller.costmap_topic | The topic to use for the costmap | string | "local_costmap/costmap_raw"     |
+| controller.footprint_topic | The topic to use for the robot's footprint | string | "local_costmap/published_footprint"     |
+| controller.transform_tolerance | Time with which to post-date the transform that is published, to indicate that this transform is valid into the future. | double | 0.1     |
+| controller.projection_time | Time to look ahead for collisions (s). | double | 5.0     |
+| controller.simulation_time_step | Time step for projections (s). | double | 0.1     |
+| controller.dock_collision_threshold | Distance (m) from the dock pose to ignore collisions. | double | 0.3     |
 
 Note: `dock_plugins` and either `docks` or `dock_database` are required.
 

nav2_docking/opennav_docking/include/opennav_docking/controller.hpp

@@ -1,4 +1,5 @@
 // Copyright (c) 2024 Open Navigation LLC
+// Copyright (c) 2024 Alberto J. Tudela Roldán
 //
 // Licensed under the Apache License, Version 2.0 (the "License");
 // you may not use this file except in compliance with the License.
@@ -16,11 +17,16 @@
 #define OPENNAV_DOCKING__CONTROLLER_HPP_
 
 #include <memory>
+#include <string>
 #include <vector>
 
 #include "geometry_msgs/msg/pose.hpp"
 #include "geometry_msgs/msg/twist.hpp"
+#include "nav2_costmap_2d/costmap_subscriber.hpp"
+#include "nav2_costmap_2d/footprint_subscriber.hpp"
+#include "nav2_costmap_2d/costmap_topic_collision_checker.hpp"
 #include "nav2_graceful_controller/smooth_control_law.hpp"
+#include "nav_msgs/msg/path.hpp"
 #include "nav2_util/lifecycle_node.hpp"
 
 namespace opennav_docking
@@ -34,36 +40,91 @@ class Controller
 public:
   /**
    * @brief Create a controller instance. Configure ROS 2 parameters.
+   *
+   * @param node Lifecycle node
+   * @param tf tf2_ros TF buffer
+   * @param fixed_frame Fixed frame
+   * @param base_frame Robot base frame
    */
-  explicit Controller(const rclcpp_lifecycle::LifecycleNode::SharedPtr & node);
+  Controller(
+    const rclcpp_lifecycle::LifecycleNode::SharedPtr & node, std::shared_ptr<tf2_ros::Buffer> tf,
+    std::string fixed_frame, std::string base_frame);
+
+  /**
+   * @brief A destructor for opennav_docking::Controller
+   */
+  ~Controller();
 
   /**
    * @brief Compute a velocity command using control law.
    * @param pose Target pose, in robot centric coordinates.
    * @param cmd Command velocity.
+   * @param is_docking If true, robot is docking. If false, robot is undocking.
    * @param backward If true, robot will drive backwards to goal.
    * @returns True if command is valid, false otherwise.
    */
   bool computeVelocityCommand(
-    const geometry_msgs::msg::Pose & pose, geometry_msgs::msg::Twist & cmd,
+    const geometry_msgs::msg::Pose & pose, geometry_msgs::msg::Twist & cmd, bool is_docking,
     bool backward = false);
 
+protected:
+  /**
+   * @brief Check if a trajectory is collision free.
+   *
+   * @param target_pose Target pose, in robot centric coordinates.
+   * @param is_docking If true, robot is docking. If false, robot is undocking.
+   * @param backward If true, robot will drive backwards to goal.
+   * @return True if trajectory is collision free.
+   */
+  bool isTrajectoryCollisionFree(
+    const geometry_msgs::msg::Pose & target_pose, bool is_docking, bool backward = false);
+
   /**
-   * @brief Callback executed when a parameter change is detected
+   * @brief Callback executed when a parameter change is detected.
+   *
    * @param event ParameterEvent message
    */
   rcl_interfaces::msg::SetParametersResult
   dynamicParametersCallback(std::vector<rclcpp::Parameter> parameters);
 
+  /**
+   * @brief Configure the collision checker.
+   *
+   * @param node Lifecycle node
+   * @param costmap_topic Costmap topic
+   * @param footprint_topic Footprint topic
+   * @param transform_tolerance Transform tolerance
+   */
+  void configureCollisionChecker(
+    const rclcpp_lifecycle::LifecycleNode::SharedPtr & node,
+    std::string costmap_topic, std::string footprint_topic, double transform_tolerance);
+
   // Dynamic parameters handler
   rclcpp::node_interfaces::OnSetParametersCallbackHandle::SharedPtr dyn_params_handler_;
   std::mutex dynamic_params_lock_;
 
-protected:
-  std::unique_ptr<nav2_graceful_controller::SmoothControlLaw> control_law_;
+  rclcpp::Logger logger_{rclcpp::get_logger("Controller")};
+  rclcpp::Clock::SharedPtr clock_;
 
+  // Smooth control law
+  std::unique_ptr<nav2_graceful_controller::SmoothControlLaw> control_law_;
   double k_phi_, k_delta_, beta_, lambda_;
   double slowdown_radius_, v_linear_min_, v_linear_max_, v_angular_max_;
+
+  // The trajectory of the robot while dock / undock for visualization / debug purposes
+  rclcpp::Publisher<nav_msgs::msg::Path>::SharedPtr trajectory_pub_;
+
+  // Used for collision checking
+  bool use_collision_detection_;
+  double projection_time_;
+  double simulation_time_step_;
+  double dock_collision_threshold_;
+  double transform_tolerance_;
+  std::shared_ptr<tf2_ros::Buffer> tf2_buffer_;
+  std::unique_ptr<nav2_costmap_2d::CostmapSubscriber> costmap_sub_;
+  std::unique_ptr<nav2_costmap_2d::FootprintSubscriber> footprint_sub_;
+  std::shared_ptr<nav2_costmap_2d::CostmapTopicCollisionChecker> collision_checker_;
+  std::string fixed_frame_, base_frame_;
 };
 
 }  // namespace opennav_docking

nav2_docking/opennav_docking/include/opennav_docking/docking_server.hpp

@@ -112,12 +112,13 @@ class DockingServer : public nav2_util::LifecycleNode
    * @param pose The pose to command towards.
    * @param linear_tolerance Pose is reached when linear distance is within this tolerance.
    * @param angular_tolerance Pose is reached when angular distance is within this tolerance.
+   * @param is_docking If true, the robot is docking. If false, the robot is undocking.
    * @param backward If true, the robot will drive backwards.
    * @returns True if pose is reached.
    */
   bool getCommandToPose(
     geometry_msgs::msg::Twist & cmd, const geometry_msgs::msg::PoseStamped & pose,
-    double linear_tolerance, double angular_tolerance, bool backward);
+    double linear_tolerance, double angular_tolerance, bool is_docking, bool backward);
 
   /**
    * @brief Get the robot pose (aka base_frame pose) in another frame.

nav2_docking/opennav_docking/src/controller.cpp

@@ -1,4 +1,5 @@
 // Copyright (c) 2024 Open Navigation LLC
+// Copyright (c) 2024 Alberto J. Tudela Roldán
 //
 // Licensed under the Apache License, Version 2.0 (the "License");
 // you may not use this file except in compliance with the License.
@@ -16,13 +17,22 @@
 
 #include "rclcpp/rclcpp.hpp"
 #include "opennav_docking/controller.hpp"
+#include "nav2_util/geometry_utils.hpp"
 #include "nav2_util/node_utils.hpp"
+#include "nav_2d_utils/conversions.hpp"
+#include "tf2/utils.h"
 
 namespace opennav_docking
 {
 
-Controller::Controller(const rclcpp_lifecycle::LifecycleNode::SharedPtr & node)
+Controller::Controller(
+  const rclcpp_lifecycle::LifecycleNode::SharedPtr & node, std::shared_ptr<tf2_ros::Buffer> tf,
+  std::string fixed_frame, std::string base_frame)
+: tf2_buffer_(tf), fixed_frame_(fixed_frame), base_frame_(base_frame)
 {
+  logger_ = node->get_logger();
+  clock_ = node->get_clock();
+
   nav2_util::declare_parameter_if_not_declared(
     node, "controller.k_phi", rclcpp::ParameterValue(3.0));
   nav2_util::declare_parameter_if_not_declared(
@@ -39,6 +49,22 @@ Controller::Controller(const rclcpp_lifecycle::LifecycleNode::SharedPtr & node)
     node, "controller.v_angular_max", rclcpp::ParameterValue(0.75));
   nav2_util::declare_parameter_if_not_declared(
     node, "controller.slowdown_radius", rclcpp::ParameterValue(0.25));
+  nav2_util::declare_parameter_if_not_declared(
+    node, "controller.use_collision_detection", rclcpp::ParameterValue(true));
+  nav2_util::declare_parameter_if_not_declared(
+    node, "controller.costmap_topic",
+    rclcpp::ParameterValue(std::string("local_costmap/costmap_raw")));
+  nav2_util::declare_parameter_if_not_declared(
+    node, "controller.footprint_topic", rclcpp::ParameterValue(
+      std::string("local_costmap/published_footprint")));
+  nav2_util::declare_parameter_if_not_declared(
+    node, "controller.transform_tolerance", rclcpp::ParameterValue(0.1));
+  nav2_util::declare_parameter_if_not_declared(
+    node, "controller.projection_time", rclcpp::ParameterValue(5.0));
+  nav2_util::declare_parameter_if_not_declared(
+    node, "controller.simulation_time_step", rclcpp::ParameterValue(0.1));
+  nav2_util::declare_parameter_if_not_declared(
+    node, "controller.dock_collision_threshold", rclcpp::ParameterValue(0.3));
 
   node->get_parameter("controller.k_phi", k_phi_);
   node->get_parameter("controller.k_delta", k_delta_);
@@ -55,16 +81,120 @@ Controller::Controller(const rclcpp_lifecycle::LifecycleNode::SharedPtr & node)
   // Add callback for dynamic parameters
   dyn_params_handler_ = node->add_on_set_parameters_callback(
     std::bind(&Controller::dynamicParametersCallback, this, std::placeholders::_1));
+
+  node->get_parameter("controller.use_collision_detection", use_collision_detection_);
+  node->get_parameter("controller.projection_time", projection_time_);
+  node->get_parameter("controller.simulation_time_step", simulation_time_step_);
+  node->get_parameter("controller.transform_tolerance", transform_tolerance_);
+
+  if (use_collision_detection_) {
+    std::string costmap_topic, footprint_topic;
+    node->get_parameter("controller.costmap_topic", costmap_topic);
+    node->get_parameter("controller.footprint_topic", footprint_topic);
+    node->get_parameter("controller.dock_collision_threshold", dock_collision_threshold_);
+    configureCollisionChecker(node, costmap_topic, footprint_topic, transform_tolerance_);
+  }
+
+  trajectory_pub_ =
+    node->create_publisher<nav_msgs::msg::Path>("docking_trajectory", 1);
+}
+
+Controller::~Controller()
+{
+  control_law_.reset();
+  trajectory_pub_.reset();
+  collision_checker_.reset();
+  costmap_sub_.reset();
+  footprint_sub_.reset();
 }
 
 bool Controller::computeVelocityCommand(
-  const geometry_msgs::msg::Pose & pose, geometry_msgs::msg::Twist & cmd, bool backward)
+  const geometry_msgs::msg::Pose & pose, geometry_msgs::msg::Twist & cmd, bool is_docking,
+  bool backward)
 {
   std::lock_guard<std::mutex> lock(dynamic_params_lock_);
   cmd = control_law_->calculateRegularVelocity(pose, backward);
+  return isTrajectoryCollisionFree(pose, is_docking, backward);
+}
+
+bool Controller::isTrajectoryCollisionFree(
+  const geometry_msgs::msg::Pose & target_pose, bool is_docking, bool backward)
+{
+  // Visualization of the trajectory
+  nav_msgs::msg::Path trajectory;
+  trajectory.header.frame_id = base_frame_;
+  trajectory.header.stamp = clock_->now();
+
+  // First pose
+  geometry_msgs::msg::PoseStamped next_pose;
+  next_pose.header.frame_id = base_frame_;
+  trajectory.poses.push_back(next_pose);
+
+  // Get the transform from base_frame to fixed_frame
+  geometry_msgs::msg::TransformStamped base_to_fixed_transform;
+  try {
+    base_to_fixed_transform = tf2_buffer_->lookupTransform(
+      fixed_frame_, base_frame_, trajectory.header.stamp,
+      tf2::durationFromSec(transform_tolerance_));
+  } catch (tf2::TransformException & ex) {
+    RCLCPP_ERROR(
+      logger_, "Could not get transform from %s to %s: %s",
+      base_frame_.c_str(), fixed_frame_.c_str(), ex.what());
+    return false;
+  }
+
+  // Generate path
+  for (double t = 0; t < projection_time_; t += simulation_time_step_) {
+    // Apply velocities to calculate next pose
+    next_pose.pose = control_law_->calculateNextPose(
+      simulation_time_step_, target_pose, next_pose.pose, backward);
+
+    // Add the pose to the trajectory for visualization
+    trajectory.poses.push_back(next_pose);
+
+    // Transform pose from base_frame into fixed_frame
+    geometry_msgs::msg::PoseStamped local_pose = next_pose;
+    local_pose.header.stamp = trajectory.header.stamp;
+    tf2::doTransform(local_pose, local_pose, base_to_fixed_transform);
+
+    // Determine the distance at which to check for collisions
+    // Skip the final segment of the trajectory for docking
+    // and the initial segment for undocking
+    // This avoids false positives when the robot is at the dock
+    double dock_collision_distance = is_docking ?
+      nav2_util::geometry_utils::euclidean_distance(target_pose, next_pose.pose) :
+      std::hypot(next_pose.pose.position.x, next_pose.pose.position.y);
+
+    // If this distance is greater than the dock_collision_threshold, check for collisions
+    if (use_collision_detection_ &&
+      dock_collision_distance > dock_collision_threshold_ &&
+      !collision_checker_->isCollisionFree(nav_2d_utils::poseToPose2D(local_pose.pose)))
+    {
+      RCLCPP_WARN(
+        logger_, "Collision detected at pose: (%.2f, %.2f, %.2f) in frame %s",
+        local_pose.pose.position.x, local_pose.pose.position.y, local_pose.pose.position.z,
+        local_pose.header.frame_id.c_str());
+      trajectory_pub_->publish(trajectory);
+      return false;
+    }
+  }
+
+  trajectory_pub_->publish(trajectory);
+
   return true;
 }
 
+void Controller::configureCollisionChecker(
+  const rclcpp_lifecycle::LifecycleNode::SharedPtr & node,
+  std::string costmap_topic, std::string footprint_topic, double transform_tolerance)
+{
+  costmap_sub_ = std::make_unique<nav2_costmap_2d::CostmapSubscriber>(node, costmap_topic);
+  footprint_sub_ = std::make_unique<nav2_costmap_2d::FootprintSubscriber>(
+    node, footprint_topic, *tf2_buffer_, base_frame_, transform_tolerance);
+  collision_checker_ = std::make_shared<nav2_costmap_2d::CostmapTopicCollisionChecker>(
+    *costmap_sub_, *footprint_sub_, node->get_name());
+}
+
 rcl_interfaces::msg::SetParametersResult
 Controller::dynamicParametersCallback(std::vector<rclcpp::Parameter> parameters)
 {
@@ -92,6 +222,12 @@ Controller::dynamicParametersCallback(std::vector<rclcpp::Parameter> parameters)
         v_angular_max_ = parameter.as_double();
       } else if (name == "controller.slowdown_radius") {
         slowdown_radius_ = parameter.as_double();
+      } else if (name == "controller.projection_time") {
+        projection_time_ = parameter.as_double();
+      } else if (name == "controller.simulation_time_step") {
+        simulation_time_step_ = parameter.as_double();
+      } else if (name == "controller.dock_collision_threshold") {
+        dock_collision_threshold_ = parameter.as_double();
       }
 
       // Update the smooth control law with the new params