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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 | |
typedef 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 > > | Graph |
The underlying roadmap graph. | |
typedef boost::graph_traits < Graph >::vertex_descriptor | Vertex |
The type for a vertex in the roadmap. | |
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 | |
PRM (const base::SpaceInformationPtr &si, bool starStrategy=false) | |
Constructor. | |
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. | |
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). | |
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. | |
virtual base::PlannerStatus | solve (const base::PlannerTerminationCondition &ptc) |
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 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. | |
virtual void | clear () |
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. | |
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. | |
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 () |
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. | |
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 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_ |
Flag indicating whether the employed connection strategy was set by the user (or defaults are assumed) | |
RNG | rng_ |
Random number generator. | |
bool | addedNewSolution_ |
A flag indicating that a solution has been added during solve() | |
boost::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_ |
Number of iterations the algorithm performed. | |
base::Cost | bestCost_ |
Best cost found so far by algorithm. |
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. Near-by 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 high-dimensional configuration spaces, IEEE Trans. on Robotics and Automation, vol. 12, pp. 566–580, Aug. 1996. DOI: [10.1109/70.508439](http://dx.doi.org/10.1109/70.508439)
[[PDF]](http://ieeexplore.ieee.org/ielx4/70/11078/00508439.pdf?tp=&arnumber=508439&isnumber=11078) [[more]](http://www.kavrakilab.org/robotics/prm.html)
Member Typedef Documentation
typedef boost::function<bool(const Vertex&, const Vertex&)> ompl::geometric::PRM::ConnectionFilter |
typedef 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 > > ompl::geometric::PRM::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.
- 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
void ompl::geometric::PRM::checkForSolution | ( | const base::PlannerTerminationCondition & | ptc, |
base::PathPtr & | solution | ||
) | [protected] |
void ompl::geometric::PRM::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:
-
connectionFilter A function that takes the new milestone, a neighboring milestone and returns whether a connection should be attempted.
void ompl::geometric::PRM::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:
-
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.
The documentation for this class was generated from the following files: