collision_check.cpp

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/*      Title     : collision_check.cpp
 *      Project   : moveit_servo
 *      Created   : 1/11/2019
 *      Author    : Brian O'Neil, Andy Zelenak, Blake Anderson
 */
 
#include <std_msgs/msg/float64.hpp>
 
#include <moveit_servo/collision_check.h>
// #include <moveit_servo/make_shared_from_pool.h>
 
static const rclcpp::Logger LOGGER = rclcpp::get_logger("moveit_servo.collision_check");
static const double MIN_RECOMMENDED_COLLISION_RATE = 10;
constexpr size_t ROS_LOG_THROTTLE_PERIOD = 30 * 1000;  // Milliseconds to throttle logs inside loops
 
namespace moveit_servo
{
// Constructor for the class that handles collision checking
CollisionCheck::CollisionCheck(const rclcpp::Node::SharedPtr& node, const ServoParameters::SharedConstPtr& parameters,
                               const planning_scene_monitor::PlanningSceneMonitorPtr& planning_scene_monitor)
  : node_(node)
  , parameters_(parameters)
  , planning_scene_monitor_(planning_scene_monitor)
  , self_velocity_scale_coefficient_(-log(0.001) / parameters->self_collision_proximity_threshold)
  , scene_velocity_scale_coefficient_(-log(0.001) / parameters->scene_collision_proximity_threshold)
  , period_(1. / parameters->collision_check_rate)
{
  // Init collision request
  collision_request_.group_name = parameters_->move_group_name;
  collision_request_.distance = true;  // enable distance-based collision checking
  collision_request_.contacts = true;  // Record the names of collision pairs
 
  if (parameters_->collision_check_rate < MIN_RECOMMENDED_COLLISION_RATE)
  {
    auto& clk = *node_->get_clock();
    RCLCPP_WARN_STREAM_THROTTLE(LOGGER, clk, ROS_LOG_THROTTLE_PERIOD,
                                "Collision check rate is low, increase it in yaml file if CPU allows");
  }
 
  // ROS pubs/subs
  collision_velocity_scale_pub_ =
      node_->create_publisher<std_msgs::msg::Float64>("~/collision_velocity_scale", rclcpp::SystemDefaultsQoS());
 
  current_state_ = planning_scene_monitor_->getStateMonitor()->getCurrentState();
}
 
void CollisionCheck::start()
{
  timer_ = node_->create_wall_timer(std::chrono::duration<double>(period_), [this]() { return run(); });
}
 
void CollisionCheck::run()
{
  if (paused_)
  {
    return;
  }
 
  // Update to the latest current state
  current_state_ = planning_scene_monitor_->getStateMonitor()->getCurrentState();
  current_state_->updateCollisionBodyTransforms();
  collision_detected_ = false;
 
  // Do a timer-safe distance-based collision detection
  collision_result_.clear();
  auto locked_scene = planning_scene_monitor::LockedPlanningSceneRO(planning_scene_monitor_);
  locked_scene->getCollisionEnv()->checkRobotCollision(collision_request_, collision_result_, *current_state_,
                                                       locked_scene->getAllowedCollisionMatrix());
  scene_collision_distance_ = collision_result_.distance;
  collision_detected_ |= collision_result_.collision;
  collision_result_.print();
 
  collision_result_.clear();
  // Self-collisions and scene collisions are checked separately so different thresholds can be used
  locked_scene->getCollisionEnvUnpadded()->checkSelfCollision(collision_request_, collision_result_, *current_state_,
                                                              locked_scene->getAllowedCollisionMatrix());
  self_collision_distance_ = collision_result_.distance;
  collision_detected_ |= collision_result_.collision;
  collision_result_.print();
 
  velocity_scale_ = 1;
  // If we're definitely in collision, stop immediately
  if (collision_detected_)
  {
    velocity_scale_ = 0;
  }
  else
  {
    // If we are far from a collision, velocity_scale should be 1.
    // If we are very close to a collision, velocity_scale should be ~zero.
    // When scene_collision_proximity_threshold is breached, start decelerating exponentially.
    if (scene_collision_distance_ < parameters_->scene_collision_proximity_threshold)
    {
      // velocity_scale = e ^ k * (collision_distance - threshold)
      // k = - ln(0.001) / collision_proximity_threshold
      // velocity_scale should equal one when collision_distance is at collision_proximity_threshold.
      // velocity_scale should equal 0.001 when collision_distance is at zero.
      velocity_scale_ = std::min(velocity_scale_,
                                 exp(scene_velocity_scale_coefficient_ *
                                     (scene_collision_distance_ - parameters_->scene_collision_proximity_threshold)));
    }
 
    if (self_collision_distance_ < parameters_->self_collision_proximity_threshold)
    {
      velocity_scale_ =
          std::min(velocity_scale_, exp(self_velocity_scale_coefficient_ *
                                        (self_collision_distance_ - parameters_->self_collision_proximity_threshold)));
    }
  }
 
  // publish message
  {
    auto msg = std::make_unique<std_msgs::msg::Float64>();
    msg->data = velocity_scale_;
    collision_velocity_scale_pub_->publish(std::move(msg));
  }
}
 
void CollisionCheck::setPaused(bool paused)
{
  paused_ = paused;
}
 
}  // namespace moveit_servo