ompl::geometric::LazyPRM Class Reference

Lazy Probabilistic RoadMap planner. More...

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

Inheritance diagram for ompl::geometric::LazyPRM:

List of all members.

Classes

struct  edge_flags_t
struct  vertex_component_t
struct  vertex_flags_t
struct  vertex_state_t

Public Types

typedef
boost::adjacency_list_traits
< boost::vecS, boost::listS,
boost::undirectedS >
::vertex_descriptor 
Vertex
 The type for a vertex in the roadmap.
typedef boost::adjacency_list
< boost::vecS, boost::listS,
boost::undirectedS,
boost::property
< vertex_state_t, base::State
*, boost::property
< boost::vertex_index_t,
unsigned long int,
boost::property
< vertex_flags_t, unsigned int,
boost::property
< vertex_component_t, unsigned
long int, boost::property
< boost::vertex_predecessor_t,
Vertex, boost::property
< boost::vertex_rank_t,
unsigned long int >
> > > > >, boost::property
< boost::edge_weight_t,
base::Cost, boost::property
< edge_flags_t, unsigned int > > > 
Graph
 The underlying roadmap graph.
typedef boost::graph_traits
< Graph >::edge_descriptor 
Edge
 The type for an edge in the roadmap.
typedef boost::shared_ptr
< NearestNeighbors< Vertex > > 
RoadmapNeighbors
 A nearest neighbors data structure for roadmap vertices.
typedef boost::function< const
std::vector< Vertex > &(const
Vertex)> 
ConnectionStrategy
 A function returning the milestones that should be attempted to connect to.
typedef boost::function< bool(const
Vertex &, const Vertex &)> 
ConnectionFilter
 A function that can reject connections.

Public Member Functions

 LazyPRM (const base::SpaceInformationPtr &si, bool starStrategy=false)
 Constructor.
void setRange (double distance)
 Set the maximum length of a motion to be added to the roadmap.
double getRange () const
 Get the range the planner is using.
template<template< typename T > class NN>
void setNearestNeighbors ()
 Set a different nearest neighbors datastructure.
virtual void setProblemDefinition (const base::ProblemDefinitionPtr &pdef)
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.
void setMaxNearestNeighbors (unsigned int k)
 Convenience function that sets the connection strategy to the default one with k nearest neighbors.
void setConnectionFilter (const ConnectionFilter &connectionFilter)
 Set the function that can reject a milestone connection.
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.
virtual void getPlannerData (base::PlannerData &data) const
 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).
virtual void setup ()
 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.
virtual void clear ()
 Clear all internal datastructures. Planner settings are not affected. Subsequent calls to solve() will ignore all previous work.
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 LazyPRM.
virtual base::PlannerStatus solve (const base::PlannerTerminationCondition &ptc)
 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. If this option is used, it is assumed the problem definition is not changed (unpredictable results otherwise). The only change in the problem definition that is accounted for is the addition of starting or goal states (but not changing previously added start/goal states). The function terminates if the call to ptc returns true.

Protected Member Functions

std::string getIterationCount () const
std::string getBestCost () const
std::string getMilestoneCountString () const
std::string getEdgeCountString () const
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 a, Vertex b)
void markComponent (Vertex v, unsigned long int newComponent)
long int solutionComponent (std::pair< std::size_t, std::size_t > *startGoalPair) const
 Check if any pair of a start state and goal state are part of the same connected component. If so, return the id of that component. Otherwise, return -1.
ompl::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.
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 Attributes

bool starStrategy_
 Flag indicating whether the default connection strategy is the Star strategy.
ConnectionStrategy connectionStrategy_
 Function that returns the milestones to attempt connections with.
ConnectionFilter connectionFilter_
 Function that can reject a milestone connection.
bool userSetConnectionStrategy_
 Flag indicating whether the employed connection strategy was set by the user (or defaults are assumed)
double maxDistance_
 The maximum length of a motion to be added to a tree.
base::StateSamplerPtr sampler_
 Sampler user for generating random in the state space.
RoadmapNeighbors nn_
 Nearest neighbors data structure.
Graph g_
 Connectivity graph.
std::vector< VertexstartM_
 Array of start milestones.
std::vector< VertexgoalM_
 Array of goal milestones.
boost::property_map< Graph,
boost::vertex_index_t >::type 
indexProperty_
 Access to the internal base::state at each Vertex.
boost::property_map< Graph,
vertex_state_t >::type 
stateProperty_
 Access to the internal base::state at each Vertex.
boost::property_map< Graph,
boost::edge_weight_t >::type 
weightProperty_
 Access to the weights of each Edge.
boost::property_map< Graph,
vertex_component_t >::type 
vertexComponentProperty_
 Access the connected component of a vertex.
boost::property_map< Graph,
vertex_flags_t >::type 
vertexValidityProperty_
 Access the validity state of a vertex.
boost::property_map< Graph,
edge_flags_t >::type 
edgeValidityProperty_
 Access the validity state of an edge.
unsigned long int componentCount_
 Number of connected components created so far. This is used as an ID only, does not represent the actual number of components currently in the graph.
std::map< unsigned long int,
unsigned long int > 
componentSize_
 The number of elements in each component in the LazyPRM roadmap.
base::OptimizationObjectivePtr opt_
 Objective cost function for PRM graph edges.
base::Cost bestCost_
unsigned long int iterations_

Static Protected Attributes

static const unsigned int VALIDITY_UNKNOWN = 0
 Flag indicating validity of an edge of a vertex.
static const unsigned int VALIDITY_TRUE = 1
 Flag indicating validity of an edge of a vertex.

Detailed Description

Lazy Probabilistic RoadMap planner.

Short description
LazyPRM is a planner that constructs a roadmap of milestones that approximate the connectivity of the state space, just like PRM does. The difference is that the planner uses lazy collision checking.
External documentation
R. Bohlin and L.E. Kavraki Path Planning Using Lazy PRM IEEE International Conference on Robotics and Automation, San Francisco, pp. 521–528, 2000. DOI: [10.1109/ROBOT.2000.844107](http://dx.doi.org/10.1109/ROBOT.2000.844107)
[[more]](http://www.kavrakilab.org/robotics/lazyprm.html)

Definition at line 75 of file LazyPRM.h.


Member Typedef Documentation

typedef boost::function<bool(const Vertex&, const Vertex&)> ompl::geometric::LazyPRM::ConnectionFilter

A function that can reject connections.

This is called after previous connections from the neighbor list have been added to the roadmap.

Definition at line 141 of file LazyPRM.h.

typedef boost::adjacency_list< boost::vecS, boost::listS, boost::undirectedS, boost::property < vertex_state_t, base::State*, boost::property < boost::vertex_index_t, unsigned long int, boost::property < vertex_flags_t, unsigned int, boost::property < vertex_component_t, unsigned long int, boost::property < boost::vertex_predecessor_t, Vertex, boost::property < boost::vertex_rank_t, unsigned long int > > > > > >, boost::property < boost::edge_weight_t, base::Cost, boost::property < edge_flags_t, unsigned int > > > ompl::geometric::LazyPRM::Graph

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. We use listS for the vertex list because vertex descriptors are invalidated by remove operations if using vecS.
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 124 of file LazyPRM.h.


Member Function Documentation

void ompl::geometric::LazyPRM::setConnectionFilter ( const ConnectionFilter connectionFilter) [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:
connectionFilterA function that takes the new milestone, a neighboring milestone and returns whether a connection should be attempted.

Definition at line 207 of file LazyPRM.h.

void ompl::geometric::LazyPRM::setConnectionStrategy ( const ConnectionStrategy connectionStrategy) [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:
pdefA 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.

Definition at line 183 of file LazyPRM.h.


The documentation for this class was generated from the following files:
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