ompl::geometric::SPARStwo Class Reference

SPArse Roadmap Spanner Version 2.0 More...

#include <ompl/geometric/planners/prm/SPARStwo.h>

Inheritance diagram for ompl::geometric::SPARStwo:

## Classes

struct  InterfaceData
Interface information storage class, which does bookkeeping for criterion four. More...

struct  vertex_color_t

struct  vertex_interface_data_t

struct  vertex_state_t

## Public Types

enum  GuardType {
START, GOAL, COVERAGE, CONNECTIVITY,
INTERFACE, QUALITY
}
Enumeration which specifies the reason a guard is added to the spanner.

typedef unsigned long VertexIndexType
The type used internally for representing vertex IDs.

typedef std::pair< VertexIndexType, VertexIndexTypeVertexPair
Pair of vertices which support an interface.

typedef std::unordered_map< VertexPair, InterfaceDataInterfaceHash
the hash which maps pairs of neighbor points to pairs of states

typedef boost::adjacency_list< boost::vecS, boost::vecS, boost::undirectedS, boost::property< vertex_state_t, base::State *, boost::property< boost::vertex_predecessor_t, VertexIndexType, boost::property< boost::vertex_rank_t, VertexIndexType, boost::property< vertex_color_t, GuardType, boost::property< vertex_interface_data_t, InterfaceHash > > > > >, boost::property< boost::edge_weight_t, base::Cost > > Graph

typedef boost::graph_traits< Graph >::vertex_descriptor Vertex
Vertex in Graph.

typedef boost::graph_traits< Graph >::edge_descriptor Edge
Edge in Graph.

Public Types inherited from ompl::base::Planner
typedef std::function< std::string()> PlannerProgressProperty
Definition of a function which returns a property about the planner's progress that can be queried by a benchmarking routine.

typedef std::map< std::string, PlannerProgressPropertyPlannerProgressProperties
A dictionary which maps the name of a progress property to the function to be used for querying that property.

## Public Member Functions

SPARStwo (const base::SpaceInformationPtr &si)
Constructor.

~SPARStwo () override
Destructor.

void setProblemDefinition (const base::ProblemDefinitionPtr &pdef) override
Set the problem definition for the planner. The problem needs to be set before calling solve(). Note: If this problem definition replaces a previous one, it may also be necessary to call clear().

void setStretchFactor (double t)
Sets the stretch factor.

void setSparseDeltaFraction (double D)
Sets vertex visibility range as a fraction of max. extent.

void setDenseDeltaFraction (double d)
Sets interface support tolerance as a fraction of max. extent.

void setMaxFailures (unsigned int m)
Sets the maximum failures until termination.

unsigned int getMaxFailures () const
Retrieve the maximum consecutive failure limit.

double getDenseDeltaFraction () const
Retrieve the dense graph interface support delta.

double getSparseDeltaFraction () const
Retrieve the sparse graph visibility range delta.

double getStretchFactor () const
Retrieve the spanner's set stretch factor.

While the termination condition permits, construct the spanner graph.

void constructRoadmap (const base::PlannerTerminationCondition &ptc, bool stopOnMaxFail)
While the termination condition permits, construct the spanner graph. If stopOnMaxFail is true, the function also terminates when the failure limit set by setMaxFailures() is reached.

base::PlannerStatus solve (const base::PlannerTerminationCondition &ptc) override
Function that can solve the motion planning problem. This function can be called multiple times on the same problem, without calling clear() in between. This allows the planner to continue work for more time on an unsolved problem, for example. Start and goal states from the currently specified ProblemDefinition are cached. This means that between calls to solve(), input states are only added, not removed. When using PRM as a multi-query planner, the input states should be however cleared, without clearing the roadmap itself. This can be done using the clearQuery() function.

void clearQuery ()
Clear the query previously loaded from the ProblemDefinition. Subsequent calls to solve() will reuse the previously computed roadmap, but will clear the set of input states constructed by the previous call to solve(). This enables multi-query functionality for PRM.

void clear () override
Clear all internal datastructures. Planner settings are not affected. Subsequent calls to solve() will ignore all previous work.

template<template< typename T > class NN>
void setNearestNeighbors ()
Set a different nearest neighbors datastructure.

void setup () override
Perform extra configuration steps, if needed. This call will also issue a call to ompl::base::SpaceInformation::setup() if needed. This must be called before solving.

unsigned int milestoneCount () const
Get the number of vertices in the sparse roadmap.

void getPlannerData (base::PlannerData &data) const override
Get information about the current run of the motion planner. Repeated calls to this function will update data (only additions are made). This is useful to see what changed in the exploration datastructure, between calls to solve(), for example (without calling clear() in between).

void printDebug (std::ostream &out=std::cout) const

std::string getIterationCount () const

std::string getBestCost () const

Public Member Functions inherited from ompl::base::Planner
Planner (const Planner &)=delete

Planneroperator= (const Planner &)=delete

Planner (SpaceInformationPtr si, std::string name)
Constructor.

virtual ~Planner ()=default
Destructor.

template<class T >
T * as ()
Cast this instance to a desired type. More...

template<class T >
const T * as () const
Cast this instance to a desired type. More...

const SpaceInformationPtrgetSpaceInformation () const
Get the space information this planner is using.

const ProblemDefinitionPtrgetProblemDefinition () const
Get the problem definition the planner is trying to solve.

const PlannerInputStatesgetPlannerInputStates () const
Get the planner input states.

PlannerStatus solve (const PlannerTerminationConditionFn &ptc, double checkInterval)
Same as above except the termination condition is only evaluated at a specified interval.

PlannerStatus solve (double solveTime)
Same as above except the termination condition is solely a time limit: the number of seconds the algorithm is allowed to spend planning.

const std::string & getName () const
Get the name of the planner.

void setName (const std::string &name)
Set the name of the planner.

const PlannerSpecsgetSpecs () const
Return the specifications (capabilities of this planner)

virtual void checkValidity ()
Check to see if the planner is in a working state (setup has been called, a goal was set, the input states seem to be in order). In case of error, this function throws an exception.

bool isSetup () const
Check if setup() was called for this planner.

ParamSetparams ()
Get the parameters for this planner.

const ParamSetparams () const
Get the parameters for this planner.

const PlannerProgressPropertiesgetPlannerProgressProperties () const
Retrieve a planner's planner progress property map.

virtual void printProperties (std::ostream &out) const
Print properties of the motion planner.

virtual void printSettings (std::ostream &out) const
Print information about the motion planner's settings.

## Protected Member Functions

void freeMemory ()
Free all the memory allocated by the planner.

void checkQueryStateInitialization ()
Check that the query vertex is initialized (used for internal nearest neighbor searches)

bool checkAddCoverage (const base::State *qNew, std::vector< Vertex > &visibleNeighborhood)
Checks to see if the sample needs to be added to ensure coverage of the space.

bool checkAddConnectivity (const base::State *qNew, std::vector< Vertex > &visibleNeighborhood)
Checks to see if the sample needs to be added to ensure connectivity.

bool checkAddInterface (const base::State *qNew, std::vector< Vertex > &graphNeighborhood, std::vector< Vertex > &visibleNeighborhood)
Checks to see if the current sample reveals the existence of an interface, and if so, tries to bridge it.

Checks vertex v for short paths through its region and adds when appropriate.

void resetFailures ()
A reset function for resetting the failures count.

void findGraphNeighbors (base::State *st, std::vector< Vertex > &graphNeighborhood, std::vector< Vertex > &visibleNeighborhood)
Finds visible nodes in the graph near st.

void approachGraph (Vertex v)
Approaches the graph from a given vertex.

Vertex findGraphRepresentative (base::State *st)
Finds the representative of the input state, st.

void findCloseRepresentatives (base::State *workArea, const base::State *qNew, Vertex qRep, std::map< Vertex, base::State *> &closeRepresentatives, const base::PlannerTerminationCondition &ptc)
Finds representatives of samples near qNew_ which are not his representative.

void updatePairPoints (Vertex rep, const base::State *q, Vertex r, const base::State *s)
High-level method which updates pair point information for repV_ with neighbor r.

void computeVPP (Vertex v, Vertex vp, std::vector< Vertex > &VPPs)
Computes all nodes which qualify as a candidate v" for v and vp.

void computeX (Vertex v, Vertex vp, Vertex vpp, std::vector< Vertex > &Xs)
Computes all nodes which qualify as a candidate x for v, v', and v".

VertexPair index (Vertex vp, Vertex vpp)
Rectifies indexing order for accessing the vertex data.

InterfaceDatagetData (Vertex v, Vertex vp, Vertex vpp)
Retrieves the Vertex data associated with v,vp,vpp.

void distanceCheck (Vertex rep, const base::State *q, Vertex r, const base::State *s, Vertex rp)
Performs distance checking for the candidate new state, q against the current information.

void abandonLists (base::State *st)
When a new guard is added at state st, finds all guards who must abandon their interface information and deletes that information.

Vertex addGuard (base::State *state, GuardType type)
Construct a guard for a given state (state) and store it in the nearest neighbors data structure.

void connectGuards (Vertex v, Vertex vp)
Connect two guards in the roadmap.

bool haveSolution (const std::vector< Vertex > &starts, const std::vector< Vertex > &goals, base::PathPtr &solution)
Check if there exists a solution, i.e., there exists a pair of milestones such that the first is in start and the second is in goal, and the two milestones are in the same connected component. If a solution is found, the path is saved.

void checkForSolution (const base::PlannerTerminationCondition &ptc, base::PathPtr &solution)

bool reachedTerminationCriterion () const
Returns true if we have reached the iteration failures limit, maxFailures_ or if a solution was added.

bool reachedFailureLimit () const
Returns whether we have reached the iteration failures limit, maxFailures_.

base::PathPtr constructSolution (Vertex start, Vertex goal) const
Given two milestones from the same connected component, construct a path connecting them and set it as the solution.

bool sameComponent (Vertex m1, Vertex m2)
Check if two milestones (m1 and m2) are part of the same connected component. This is not a const function since we use incremental connected components from boost.

double distanceFunction (const Vertex a, const Vertex b) const
Compute distance between two milestones (this is simply distance between the states of the milestones)

base::Cost costHeuristic (Vertex u, Vertex v) const
Given two vertices, returns a heuristic on the cost of the path connecting them. This method wraps OptimizationObjective::motionCostHeuristic.

Protected Member Functions inherited from ompl::base::Planner
template<typename T , typename PlannerType , typename SetterType , typename GetterType >
void declareParam (const std::string &name, const PlannerType &planner, const SetterType &setter, const GetterType &getter, const std::string &rangeSuggestion="")
This function declares a parameter for this planner instance, and specifies the setter and getter functions.

template<typename T , typename PlannerType , typename SetterType >
void declareParam (const std::string &name, const PlannerType &planner, const SetterType &setter, const std::string &rangeSuggestion="")
This function declares a parameter for this planner instance, and specifies the setter function.

void addPlannerProgressProperty (const std::string &progressPropertyName, const PlannerProgressProperty &prop)
Add a planner progress property called progressPropertyName with a property querying function prop to this planner's progress property map.

## Protected Attributes

base::ValidStateSamplerPtr sampler_
Sampler user for generating valid samples in the state space.

std::shared_ptr< NearestNeighbors< Vertex > > nn_
Nearest neighbors data structure.

Graph g_
Connectivity graph.

std::vector< VertexstartM_
Array of start milestones.

std::vector< VertexgoalM_
Array of goal milestones.

Vertex queryVertex_
Vertex for performing nearest neighbor queries.

double stretchFactor_ {3.}
Stretch Factor as per graph spanner literature (multiplicative bound on path quality)

double sparseDeltaFraction_ {.25}
Maximum visibility range for nodes in the graph as a fraction of maximum extent.

double denseDeltaFraction_ {.001}
Maximum range for allowing two samples to support an interface as a fraction of maximum extent.

unsigned int maxFailures_ {5000}
The number of consecutive failures to add to the graph before termination.

unsigned int nearSamplePoints_
Number of sample points to use when trying to detect interfaces.

boost::property_map< Graph, vertex_state_t >::type stateProperty_

PathSimplifierPtr psimp_
A path simplifier used to simplify dense paths added to the graph.

boost::property_map< Graph, boost::edge_weight_t >::type weightProperty_

boost::property_map< Graph, vertex_color_t >::type colorProperty_

boost::property_map< Graph, vertex_interface_data_t >::type interfaceDataProperty_

boost::disjoint_sets< boost::property_map< Graph, boost::vertex_rank_t >::type, boost::property_map< Graph, boost::vertex_predecessor_t >::type > disjointSets_
Data structure that maintains the connected components.

RNG rng_
Random number generator.

A flag indicating that a solution has been added during solve()

unsigned int consecutiveFailures_ {0}
A counter for the number of consecutive failed iterations of the algorithm.

double sparseDelta_ {0.}
Maximum visibility range for nodes in the graph.

double denseDelta_ {0.}
Maximum range for allowing two samples to support an interface.

std::mutex graphMutex_

base::OptimizationObjectivePtr opt_
Objective cost function for PRM graph edges.

long unsigned int iterations_ {0ul}
A counter for the number of iterations of the algorithm.

base::Cost bestCost_ {std::numeric_limits<double>::quiet_NaN()}
Best cost found so far by algorithm.

Protected Attributes inherited from ompl::base::Planner
SpaceInformationPtr si_
The space information for which planning is done.

ProblemDefinitionPtr pdef_
The user set problem definition.

PlannerInputStates pis_
Utility class to extract valid input states.

std::string name_
The name of this planner.

PlannerSpecs specs_
The specifications of the planner (its capabilities)

ParamSet params_
A map from parameter names to parameter instances for this planner. This field is populated by the declareParam() function.

PlannerProgressProperties plannerProgressProperties_
A mapping between this planner's progress property names and the functions used for querying those progress properties.

bool setup_
Flag indicating whether setup() has been called.

## Detailed Description

Short description
SPARStwo is a variant of the SPARS algorithm which removes the dependency on having the dense graph, D. It works through similar mechanics, but uses a different approach to identifying interfaces and computing shortest paths through said interfaces.
External documentation
A. Dobson, K. Bekris, Improving Sparse Roadmap Spanners, IEEE International Conference on Robotics and Automation (ICRA) May 2013. [PDF]

Definition at line 77 of file SPARStwo.h.

## ◆ Graph

 typedef boost::adjacency_list< boost::vecS, boost::vecS, boost::undirectedS, boost::property< vertex_state_t, base::State *, boost::property< boost::vertex_predecessor_t, VertexIndexType, boost::property > > > >, boost::property > ompl::geometric::SPARStwo::Graph

Any BGL graph representation could be used here. Because we
Obviously, a ompl::base::State* vertex property is required.
The incremental connected components algorithm requires vertex_predecessor_t and vertex_rank_t properties. If boost::vecS is not used for vertex storage, then there must also be a boost:vertex_index_t property manually added.
Edges should be undirected and have a weight property.

Definition at line 214 of file SPARStwo.h.

## ◆ checkForSolution()

 void ompl::geometric::SPARStwo::checkForSolution ( const base::PlannerTerminationCondition & ptc, base::PathPtr & solution )
protected