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ompl::geometric::PRM Class Reference
Probabilistic RoadMap planner. More...
#include <ompl/geometric/planners/prm/PRM.h>
Inheritance diagram for ompl::geometric::PRM:
Classes  
struct  vertex_state_t 
struct  vertex_successful_connection_attempts_t 
struct  vertex_total_connection_attempts_t 
Public Types  
using  Graph = boost::adjacency_list< boost::vecS, boost::vecS, boost::undirectedS, boost::property< vertex_state_t, base::State *, boost::property< vertex_total_connection_attempts_t, unsigned long int, boost::property< vertex_successful_connection_attempts_t, unsigned long int, boost::property< boost::vertex_predecessor_t, unsigned long int, boost::property< boost::vertex_rank_t, unsigned long int > >> >>, boost::property< boost::edge_weight_t, base::Cost > > 
The underlying roadmap graph. More...  
using  Vertex = boost::graph_traits< Graph >::vertex_descriptor 
The type for a vertex in the roadmap.  
using  Edge = boost::graph_traits< Graph >::edge_descriptor 
The type for an edge in the roadmap.  
using  RoadmapNeighbors = std::shared_ptr< NearestNeighbors< Vertex > > 
A nearest neighbors data structure for roadmap vertices.  
using  ConnectionStrategy = std::function< const std::vector< Vertex > &(const Vertex)> 
A function returning the milestones that should be attempted to connect to.  
using  ConnectionFilter = std::function< bool(const Vertex &, const Vertex &)> 
A function that can reject connections. More...  
Public Types inherited from ompl::base::Planner  
using  PlannerProgressProperty = std::function< std::string()> 
Definition of a function which returns a property about the planner's progress that can be queried by a benchmarking routine.  
using  PlannerProgressProperties = std::map< std::string, PlannerProgressProperty > 
A dictionary which maps the name of a progress property to the function to be used for querying that property.  
Public Member Functions  
PRM (const base::SpaceInformationPtr &si, bool starStrategy=false)  
Constructor.  
PRM (const base::PlannerData &data, bool starStrategy=false)  
Constructor.  
void  setProblemDefinition (const base::ProblemDefinitionPtr &pdef) override 
void  setConnectionStrategy (const ConnectionStrategy &connectionStrategy) 
Set the connection strategy function that specifies the milestones that connection attempts will be make to for a given milestone. More...  
void  setDefaultConnectionStrategy () 
void  setMaxNearestNeighbors (unsigned int k) 
Convenience function that sets the connection strategy to the default one with k nearest neighbors.  
unsigned int  getMaxNearestNeighbors () const 
return the maximum number of nearest neighbors to connect a sample to More...  
void  setConnectionFilter (const ConnectionFilter &connectionFilter) 
Set the function that can reject a milestone connection. More...  
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  constructRoadmap (const base::PlannerTerminationCondition &ptc) 
While the termination condition allows, this function will construct the roadmap (using growRoadmap() and expandRoadmap(), maintaining a 2:1 ratio for growing/expansion of roadmap)  
void  growRoadmap (double growTime) 
If the user desires, the roadmap can be improved for the given time (seconds). The solve() method will also improve the roadmap, as needed.  
void  growRoadmap (const base::PlannerTerminationCondition &ptc) 
If the user desires, the roadmap can be improved until a given condition is true. The solve() method will also improve the roadmap, as needed.  
void  expandRoadmap (double expandTime) 
Attempt to connect disjoint components in the roadmap using random bouncing motions (the PRM expansion step) for the given time (seconds).  
void  expandRoadmap (const base::PlannerTerminationCondition &ptc) 
Attempt to connect disjoint components in the roadmap using random bouncing motions (the PRM expansion step) until the given condition evaluates true.  
base::PlannerStatus  solve (const base::PlannerTerminationCondition &ptc) override 
Function that can solve the motion planning problem. Grows a roadmap using constructRoadmap(). 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 multiquery planner, the input states should be however cleared, without clearing the roadmap itself. This can be done using the clearQuery() function.  
void  clearQuery () override 
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 multiquery 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.  
const Graph &  getRoadmap () const 
unsigned long int  milestoneCount () const 
Return the number of milestones currently in the graph.  
unsigned long int  edgeCount () const 
Return the number of edges currently in the graph.  
const RoadmapNeighbors &  getNearestNeighbors () 
Public Member Functions inherited from ompl::base::Planner  
Planner (const Planner &)=delete  
Planner &  operator= (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 SpaceInformationPtr &  getSpaceInformation () const 
Get the space information this planner is using.  
const ProblemDefinitionPtr &  getProblemDefinition () const 
Get the problem definition the planner is trying to solve.  
ProblemDefinitionPtr &  getProblemDefinition () 
Get the problem definition the planner is trying to solve.  
const PlannerInputStates &  getPlannerInputStates () const 
Get the planner input states.  
virtual void  setProblemDefinition (const ProblemDefinitionPtr &pdef) 
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() or clearQuery().  
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 PlannerSpecs &  getSpecs () 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.  
ParamSet &  params () 
Get the parameters for this planner.  
const ParamSet &  params () const 
Get the parameters for this planner.  
const PlannerProgressProperties &  getPlannerProgressProperties () 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.  
Vertex  addMilestone (base::State *state) 
Construct a milestone for a given state (state), store it in the nearest neighbors data structure and then connect it to the roadmap in accordance to the connection strategy.  
void  uniteComponents (Vertex m1, Vertex m2) 
Make two milestones (m1 and m2) be part of the same connected component. The component with fewer elements will get the id of the component with more elements.  
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.  
void  growRoadmap (const base::PlannerTerminationCondition &ptc, base::State *workState) 
Randomly sample the state space, add and connect milestones in the roadmap. Stop this process when the termination condition ptc returns true. Use workState as temporary memory.  
void  expandRoadmap (const base::PlannerTerminationCondition &ptc, std::vector< base::State * > &workStates) 
Attempt to connect disjoint components in the roadmap using random bounding motions (the PRM expansion step)  
void  checkForSolution (const base::PlannerTerminationCondition &ptc, base::PathPtr &solution) 
bool  maybeConstructSolution (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, it is constructed in the solution argument.  
ompl::base::Cost  constructApproximateSolution (const std::vector< Vertex > &starts, const std::vector< Vertex > &goals, base::PathPtr &solution) 
(Assuming that there is always an approximate solution), finds an approximate solution.  
bool  addedNewSolution () const 
Returns the value of the addedNewSolution_ member.  
base::PathPtr  constructSolution (const Vertex &start, const Vertex &goal) 
Given two milestones from the same connected component, construct a path connecting them and set it as the solution.  
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.  
double  distanceFunction (const Vertex a, const Vertex b) const 
Compute distance between two milestones (this is simply distance between the states of the milestones)  
std::string  getIterationCount () const 
std::string  getBestCost () const 
std::string  getMilestoneCountString () const 
std::string  getEdgeCountString () const 
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  
bool  starStrategy_ 
Flag indicating whether the default connection strategy is the Star strategy.  
base::ValidStateSamplerPtr  sampler_ 
Sampler user for generating valid samples in the state space.  
base::StateSamplerPtr  simpleSampler_ 
Sampler user for generating random in the state space.  
RoadmapNeighbors  nn_ 
Nearest neighbors data structure.  
Graph  g_ 
Connectivity graph.  
std::vector< Vertex >  startM_ 
Array of start milestones.  
std::vector< Vertex >  goalM_ 
Array of goal milestones.  
boost::property_map< Graph, vertex_state_t >::type  stateProperty_ 
Access to the internal base::state at each Vertex.  
boost::property_map< Graph, vertex_total_connection_attempts_t >::type  totalConnectionAttemptsProperty_ 
Access to the number of total connection attempts for a vertex.  
boost::property_map< Graph, vertex_successful_connection_attempts_t >::type  successfulConnectionAttemptsProperty_ 
Access to the number of successful connection attempts for a vertex.  
boost::property_map< Graph, boost::edge_weight_t >::type  weightProperty_ 
Access to the weights of each Edge.  
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.  
ConnectionStrategy  connectionStrategy_ 
Function that returns the milestones to attempt connections with.  
ConnectionFilter  connectionFilter_ 
Function that can reject a milestone connection.  
bool  userSetConnectionStrategy_ {false} 
Flag indicating whether the employed connection strategy was set by the user (or defaults are assumed)  
RNG  rng_ 
Random number generator.  
bool  addedNewSolution_ {false} 
A flag indicating that a solution has been added during solve()  
std::mutex  graphMutex_ 
Mutex to guard access to the Graph member (g_)  
base::OptimizationObjectivePtr  opt_ 
Objective cost function for PRM graph edges.  
unsigned long int  iterations_ {0} 
Number of iterations the algorithm performed.  
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
Probabilistic RoadMap planner.
 Short description
 PRM is a planner that constructs a roadmap of milestones that approximate the connectivity of the state space. The milestones are valid states in the state space. Nearby milestones are connected by valid motions. Finding a motion plan that connects two given states is reduced to a discrete search (this implementation uses A*) in the roadmap.
 External documentation
 L.E. Kavraki, P.Švestka, J.C. Latombe, and M.H. Overmars, Probabilistic roadmaps for path planning in highdimensional configuration spaces, IEEE Trans. on Robotics and Automation, vol. 12, pp. 566–580, Aug. 1996. DOI: 10.1109/70.508439
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Member Typedef Documentation
◆ ConnectionFilter
using ompl::geometric::PRM::ConnectionFilter = std::function<bool(const Vertex &, const Vertex &)> 
◆ Graph
using ompl::geometric::PRM::Graph = boost::adjacency_list< boost::vecS, boost::vecS, boost::undirectedS, boost::property< vertex_state_t, base::State *, boost::property< vertex_total_connection_attempts_t, unsigned long int, boost::property<vertex_successful_connection_attempts_t, unsigned long int, boost::property<boost::vertex_predecessor_t, unsigned long int, boost::property<boost::vertex_rank_t, unsigned long int> >> >>, boost::property<boost::edge_weight_t, base::Cost> > 
The underlying roadmap graph.
 Any BGL graph representation could be used here. Because we
 expect the roadmap to be sparse (m<n^2), an adjacency_list is more appropriate than an adjacency_matrix.
 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.
Member Function Documentation
◆ checkForSolution()

protected 
◆ getMaxNearestNeighbors()
unsigned int ompl::geometric::PRM::getMaxNearestNeighbors  (  )  const 
◆ setConnectionFilter()

inline 
Set the function that can reject a milestone connection.
 The given function is called immediately before a connection
 is checked for collision and added to the roadmap. Other neighbors may have already been connected before this function is called. This allows certain heuristics that use the structure of the roadmap (like connected components or useful cycles) to be implemented by changing this function.
 Parameters

connectionFilter A function that takes the new milestone, a neighboring milestone and returns whether a connection should be attempted.
◆ setConnectionStrategy()

inline 
Set the connection strategy function that specifies the milestones that connection attempts will be make to for a given milestone.
 The behavior and performance of PRM can be changed drastically
 by varying the number and properties if the milestones that are connected to each other.
 Parameters

pdef A function that takes a milestone as an argument and returns a collection of other milestones to which a connection attempt must be made. The default connection strategy is to connect a milestone's 10 closest neighbors.
◆ setDefaultConnectionStrategy()
void ompl::geometric::PRM::setDefaultConnectionStrategy  (  ) 
The documentation for this class was generated from the following files: