node_lattice.hpp

// Copyright (c) 2020, 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_SMAC_PLANNER__NODE_LATTICE_HPP_
#define NAV2_SMAC_PLANNER__NODE_LATTICE_HPP_
 
#include <functional>
#include <memory>
#include <string>
#include <vector>
 
#include "ompl/base/StateSpace.h"
 
#include "nav2_smac_planner/constants.hpp"
#include "nav2_smac_planner/types.hpp"
#include "nav2_smac_planner/collision_checker.hpp"
#include "nav2_smac_planner/node_hybrid.hpp"
#include "nav2_smac_planner/utils.hpp"
 
namespace nav2_smac_planner
{
 
// forward declare
class NodeLattice;
class NodeHybrid;
 
struct LatticeMotionTable
{
  LatticeMotionTable() {}
 
  void initMotionModel(
    unsigned int & size_x_in,
    SearchInfo & search_info);
 
  MotionPrimitivePtrs getMotionPrimitives(
    const NodeLattice * node,
    unsigned int & direction_change_index);
 
  static LatticeMetadata getLatticeMetadata(const std::string & lattice_filepath);
 
  unsigned int getClosestAngularBin(const double & theta);
 
  float & getAngleFromBin(const unsigned int & bin_idx);
 
  double getAngle(const double & theta);
 
  unsigned int size_x;
  unsigned int num_angle_quantization;
  float change_penalty;
  float non_straight_penalty;
  float cost_penalty;
  float reverse_penalty;
  float travel_distance_reward;
  float rotation_penalty;
  float min_turning_radius;
  bool allow_reverse_expansion;
  std::vector<std::vector<MotionPrimitive>> motion_primitives;
  ompl::base::StateSpacePtr state_space;
  std::vector<TrigValues> trig_values;
  std::string current_lattice_filepath;
  LatticeMetadata lattice_metadata;
  MotionModel motion_model = MotionModel::UNKNOWN;
};
 
class NodeLattice
{
public:
  typedef NodeLattice * NodePtr;
  typedef std::unique_ptr<std::vector<NodeLattice>> Graph;
  typedef std::vector<NodePtr> NodeVector;
  typedef NodeHybrid::Coordinates Coordinates;
  typedef NodeHybrid::CoordinateVector CoordinateVector;
 
  explicit NodeLattice(const uint64_t index);
 
  ~NodeLattice();
 
  bool operator==(const NodeLattice & rhs)
  {
    return this->_index == rhs._index;
  }
 
  inline void setPose(const Coordinates & pose_in)
  {
    pose = pose_in;
  }
 
  void reset();
 
  inline void setMotionPrimitive(MotionPrimitive * prim)
  {
    _motion_primitive = prim;
  }
 
  inline MotionPrimitive * & getMotionPrimitive()
  {
    return _motion_primitive;
  }
 
  inline float getAccumulatedCost()
  {
    return _accumulated_cost;
  }
 
  inline void setAccumulatedCost(const float & cost_in)
  {
    _accumulated_cost = cost_in;
  }
 
  inline float getCost()
  {
    return _cell_cost;
  }
 
  inline bool wasVisited()
  {
    return _was_visited;
  }
 
  inline void visited()
  {
    _was_visited = true;
  }
 
  inline uint64_t getIndex()
  {
    return _index;
  }
 
  inline void backwards(bool back = true)
  {
    _backwards = back;
  }
 
  inline bool isBackward()
  {
    return _backwards;
  }
 
  bool isNodeValid(
    const bool & traverse_unknown,
    GridCollisionChecker * collision_checker,
    MotionPrimitive * primitive = nullptr,
    bool is_backwards = false);
 
  float getTraversalCost(const NodePtr & child);
 
  static inline uint64_t getIndex(
    const unsigned int & x, const unsigned int & y, const unsigned int & angle)
  {
    // Hybrid-A* and State Lattice share a coordinate system
    return NodeHybrid::getIndex(
      x, y, angle, motion_table.size_x,
      motion_table.num_angle_quantization);
  }
 
  static inline Coordinates getCoords(
    const uint64_t & index,
    const unsigned int & width, const unsigned int & angle_quantization)
  {
    // Hybrid-A* and State Lattice share a coordinate system
    return NodeHybrid::Coordinates(
      (index / angle_quantization) % width,    // x
      index / (angle_quantization * width),    // y
      index % angle_quantization);    // theta
  }
 
  static float getHeuristicCost(
    const Coordinates & node_coords,
    const CoordinateVector & goals_coords);
 
  static void initMotionModel(
    const MotionModel & motion_model,
    unsigned int & size_x,
    unsigned int & size_y,
    unsigned int & angle_quantization,
    SearchInfo & search_info);
 
  static void precomputeDistanceHeuristic(
    const float & lookup_table_dim,
    const MotionModel & motion_model,
    const unsigned int & dim_3_size,
    const SearchInfo & search_info);
 
  static void resetObstacleHeuristic(
    std::shared_ptr<nav2_costmap_2d::Costmap2DROS> costmap_ros,
    const unsigned int & start_x, const unsigned int & start_y,
    const unsigned int & goal_x, const unsigned int & goal_y)
  {
    // State Lattice and Hybrid-A* share this heuristics
    NodeHybrid::resetObstacleHeuristic(costmap_ros, start_x, start_y, goal_x, goal_y);
  }
 
  static float getObstacleHeuristic(
    const Coordinates & node_coords,
    const Coordinates & goal_coords,
    const double & cost_penalty)
  {
    return NodeHybrid::getObstacleHeuristic(node_coords, goal_coords, cost_penalty);
  }
 
  static float getDistanceHeuristic(
    const Coordinates & node_coords,
    const Coordinates & goal_coords,
    const float & obstacle_heuristic);
 
  void getNeighbors(
    std::function<bool(const uint64_t &,
    nav2_smac_planner::NodeLattice * &)> & validity_checker,
    GridCollisionChecker * collision_checker,
    const bool & traverse_unknown,
    NodeVector & neighbors);
 
  bool backtracePath(CoordinateVector & path);
 
  void addNodeToPath(NodePtr current_node, CoordinateVector & path);
 
  NodeLattice * parent;
  Coordinates pose;
  static LatticeMotionTable motion_table;
  // Dubin / Reeds-Shepp lookup and size for dereferencing
  static LookupTable dist_heuristic_lookup_table;
  static float size_lookup;
 
private:
  float _cell_cost;
  float _accumulated_cost;
  uint64_t _index;
  bool _was_visited;
  MotionPrimitive * _motion_primitive;
  bool _backwards;
  bool _is_node_valid{false};
};
 
}  // namespace nav2_smac_planner
 
#endif  // NAV2_SMAC_PLANNER__NODE_LATTICE_HPP_