Syclop.h

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/* Author: Matt Maly */
 
#ifndef OMPL_CONTROL_PLANNERS_SYCLOP_SYCLOP_
#define OMPL_CONTROL_PLANNERS_SYCLOP_SYCLOP_
 
#include <boost/graph/astar_search.hpp>
#include <boost/graph/graph_traits.hpp>
#include <boost/graph/adjacency_list.hpp>
#include <unordered_map>
#include "ompl/control/planners/PlannerIncludes.h"
#include "ompl/control/planners/syclop/Decomposition.h"
#include "ompl/control/planners/syclop/GridDecomposition.h"
#include "ompl/datastructures/PDF.h"
#include "ompl/util/Hash.h"
#include <functional>
#include <map>
#include <utility>
#include <vector>
 
namespace ompl
{
    namespace control
    {

        class Syclop : public base::Planner
        {
        public:
            using EdgeCostFactorFn = std::function<double(int, int)>;

            using LeadComputeFn = std::function<void(int, int, std::vector<int> &)>;

            Syclop(const SpaceInformationPtr &si, DecompositionPtr d, const std::string &plannerName)
              : ompl::base::Planner(si, plannerName)
              , siC_(si.get())
              , decomp_(std::move(d))
              , covGrid_(Defaults::COVGRID_LENGTH, decomp_)
            {
                specs_.approximateSolutions = true;
 
                Planner::declareParam<int>("free_volume_samples", this, &Syclop::setNumFreeVolumeSamples,
                                           &Syclop::getNumFreeVolumeSamples, "10000:10000:500000");
                Planner::declareParam<int>("num_region_expansions", this, &Syclop::setNumRegionExpansions,
                                           &Syclop::getNumRegionExpansions, "10:10:500");
                Planner::declareParam<int>("num_tree_expansions", this, &Syclop::setNumTreeExpansions,
                                           &Syclop::getNumTreeExpansions, "0:1:100");
                Planner::declareParam<double>("prob_abandon_lead_early", this, &Syclop::setProbAbandonLeadEarly,
                                              &Syclop::getProbAbandonLeadEarly, "0.:.05:1.");
                Planner::declareParam<double>("prob_add_available_regions", this,
                                              &Syclop::setProbAddingToAvailableRegions,
                                              &Syclop::getProbAddingToAvailableRegions, "0.:.05:1.");
                Planner::declareParam<double>("prob_shortest_path_lead", this, &Syclop::setProbShortestPathLead,
                                              &Syclop::getProbShortestPathLead, "0.:.05:1.");
            }
 
            ~Syclop() override = default;

 
            void setup() override;
 
            void clear() override;

            base::PlannerStatus solve(const base::PlannerTerminationCondition &ptc) override;


            void setLeadComputeFn(const LeadComputeFn &compute);

            void addEdgeCostFactor(const EdgeCostFactorFn &factor);

            void clearEdgeCostFactors();

            int getNumFreeVolumeSamples() const
            {
                return numFreeVolSamples_;
            }

            void setNumFreeVolumeSamples(int numSamples)
            {
                numFreeVolSamples_ = numSamples;
            }

            double getProbShortestPathLead() const
            {
                return probShortestPath_;
            }

            void setProbShortestPathLead(double probability)
            {
                probShortestPath_ = probability;
            }

            double getProbAddingToAvailableRegions() const
            {
                return probKeepAddingToAvail_;
            }

            void setProbAddingToAvailableRegions(double probability)
            {
                probKeepAddingToAvail_ = probability;
            }

            int getNumRegionExpansions() const
            {
                return numRegionExpansions_;
            }

            void setNumRegionExpansions(int regionExpansions)
            {
                numRegionExpansions_ = regionExpansions;
            }

            int getNumTreeExpansions() const
            {
                return numTreeSelections_;
            }

            void setNumTreeExpansions(int treeExpansions)
            {
                numTreeSelections_ = treeExpansions;
            }

            double getProbAbandonLeadEarly() const
            {
                return probAbandonLeadEarly_;
            }

            void setProbAbandonLeadEarly(double probability)
            {
                probAbandonLeadEarly_ = probability;
            }


            struct Defaults
            {
                static const int NUM_FREEVOL_SAMPLES = 100000;
                static const int COVGRID_LENGTH = 128;
                static const int NUM_REGION_EXPANSIONS = 100;
                static const int NUM_TREE_SELECTIONS = 1;
                // C++ standard prohibits non-integral static const member initialization
                // These constants are set in Syclop.cpp.  C++11 standard changes this
                // with the constexpr keyword, but for compatibility this is not done.
                static const double PROB_ABANDON_LEAD_EARLY /*= 0.25*/;
                static const double PROB_KEEP_ADDING_TO_AVAIL /*= 0.50*/;
                static const double PROB_SHORTEST_PATH /*= 0.95*/;
            };
 
        protected:
            class Motion
            {
            public:
                Motion() = default;

                Motion(const SpaceInformation *si) : state(si->allocState()), control(si->allocControl())
                {
                }
                virtual ~Motion() = default;
                base::State *state{nullptr};
                Control *control{nullptr};
                const Motion *parent{nullptr};
                unsigned int steps{0};
            };

            class Region
            {
            public:
                Region() = default;
                virtual ~Region() = default;
 
                Region(const Region &) = default;
                Region &operator=(const Region &) = default;
                Region(Region &&) = default;
                Region &operator=(Region &&) = default;

                void clear()
                {
                    motions.clear();
                    covGridCells.clear();
                    pdfElem = nullptr;
                }

                std::set<int> covGridCells;
                std::vector<Motion *> motions;
                double volume;
                double freeVolume;
                double percentValidCells;
                double weight;
                double alpha;
                int index;
                unsigned int numSelections;
                PDF<int>::Element *pdfElem;
            };

            class Adjacency
            {
            public:
                Adjacency() = default;
                virtual ~Adjacency() = default;
                void clear()
                {
                    covGridCells.clear();
                }

                std::set<int> covGridCells = {};
                const Region *source = {nullptr};
                const Region *target = {nullptr};
                double cost = {0.};
                int numLeadInclusions = {0};
                int numSelections = {0};
                bool empty = {false};
            };

            virtual Motion *addRoot(const base::State *s) = 0;

            virtual void selectAndExtend(Region &region, std::vector<Motion *> &newMotions) = 0;

            inline const Region &getRegionFromIndex(const int rid) const
            {
                return graph_[boost::vertex(rid, graph_)];
            }

            int numFreeVolSamples_{Defaults::NUM_FREEVOL_SAMPLES};

            double probShortestPath_{Defaults::PROB_SHORTEST_PATH};

            double probKeepAddingToAvail_{Defaults::PROB_KEEP_ADDING_TO_AVAIL};

            int numRegionExpansions_{Defaults::NUM_REGION_EXPANSIONS};

            int numTreeSelections_{Defaults::NUM_TREE_SELECTIONS};

            double probAbandonLeadEarly_{Defaults::PROB_ABANDON_LEAD_EARLY};

            const SpaceInformation *siC_;

            DecompositionPtr decomp_;

            RNG rng_;
 
        private:

            struct HashRegionPair
            {
                size_t operator()(const std::pair<int, int> &p) const
                {
                    std::size_t hash = std::hash<int>()(p.first);
                    hash_combine(hash, p.second);
                    return hash;
                }
            };

            class CoverageGrid : public GridDecomposition
            {
            public:
                CoverageGrid(const int len, const DecompositionPtr &d)
                  : GridDecomposition(len, d->getDimension(), d->getBounds()), decomp(d)
                {
                }
 
                ~CoverageGrid() override = default;

                void project(const base::State *s, std::vector<double> &coord) const override
                {
                    decomp->project(s, coord);
                }

                void sampleFullState(const base::StateSamplerPtr & /*sampler*/, const std::vector<double> & /*coord*/,
                                     base::State * /*s*/) const override
                {
                }
 
            protected:
                const DecompositionPtr &decomp;
            };
 
            using RegionGraph = boost::adjacency_list<boost::vecS, boost::vecS, boost::directedS, Region, Adjacency>;
            using Vertex = boost::graph_traits<RegionGraph>::vertex_descriptor;
            using VertexIter = boost::graph_traits<RegionGraph>::vertex_iterator;
            using VertexIndexMap = boost::property_map<RegionGraph, boost::vertex_index_t>::type;
            using EdgeIter = boost::graph_traits<RegionGraph>::edge_iterator;

            friend class DecompositionHeuristic;
 
            class DecompositionHeuristic : public boost::astar_heuristic<RegionGraph, double>
            {
            public:
                DecompositionHeuristic(const Syclop *s, const Region &goal) : syclop(s), goalRegion(goal)
                {
                }
 
                double operator()(Vertex v)
                {
                    const Region &region = syclop->getRegionFromIndex(v);
                    return region.alpha * goalRegion.alpha;
                }
 
            private:
                const Syclop *syclop;
                const Region &goalRegion;
            };
 
            struct found_goal
            {
            };
 
            class GoalVisitor : public boost::default_astar_visitor
            {
            public:
                GoalVisitor(const int goal) : goalRegion(goal)
                {
                }
                void examine_vertex(Vertex v, const RegionGraph & /*g*/)
                {
                    if (static_cast<int>(v) == goalRegion)
                        throw found_goal();
                }
 
            private:
                const int goalRegion;
            };

            class RegionSet
            {
            public:
                int sampleUniform()
                {
                    if (empty())
                        return -1;
                    return regions.sample(rng.uniform01());
                }
                void insert(const int r)
                {
                    if (regToElem.count(r) == 0)
                        regToElem[r] = regions.add(r, 1);
                    else
                    {
                        PDF<int>::Element *elem = regToElem[r];
                        regions.update(elem, regions.getWeight(elem) + 1);
                    }
                }
                void clear()
                {
                    regions.clear();
                    regToElem.clear();
                }
                std::size_t size() const
                {
                    return regions.size();
                }
                bool empty() const
                {
                    return regions.empty();
                }
 
            private:
                RNG rng;
                PDF<int> regions;
                std::unordered_map<int, PDF<int>::Element *> regToElem;
            };

            void initRegion(Region &r);

            void setupRegionEstimates();

            void updateRegion(Region &r);

            void initEdge(Adjacency &adj, const Region *source, const Region *target);

            void setupEdgeEstimates();

            void updateEdge(Adjacency &a);

            bool updateCoverageEstimate(Region &r, const base::State *s);

            bool updateConnectionEstimate(const Region &c, const Region &d, const base::State *s);

            void buildGraph();

            void clearGraphDetails();

            int selectRegion();

            void computeAvailableRegions();

            void defaultComputeLead(int startRegion, int goalRegion, std::vector<int> &lead);

            double defaultEdgeCost(int r, int s);

            LeadComputeFn leadComputeFn;
            std::vector<int> lead_;
            PDF<int> availDist_;
            std::vector<EdgeCostFactorFn> edgeCostFactors_;
            CoverageGrid covGrid_;
            RegionGraph graph_;
            bool graphReady_{false};
            std::unordered_map<std::pair<int, int>, Adjacency *, HashRegionPair> regionsToEdge_;
            unsigned int numMotions_{0};
            RegionSet startRegions_;
            RegionSet goalRegions_;
        };
    }  // namespace control
}  // namespace ompl
 
#endif