ompl::geometric::SBL Class Reference

Single-Query Bi-Directional Probabilistic Roadmap Planner with Lazy Collision Checking. More...

#include <ompl/geometric/planners/sbl/SBL.h>

Inheritance diagram for ompl::geometric::SBL:

## Classes

class  Motion
Representation of a motion. More...

struct  MotionInfo
A struct containing an array of motions and a corresponding PDF element. More...

struct  TreeData
Representation of a search tree. Two instances will be used. One for start and one for goal. More...

## Public Member Functions

SBL (const base::SpaceInformationPtr &si)
The constructor needs the instance of the space information.

void setProjectionEvaluator (const base::ProjectionEvaluatorPtr &projectionEvaluator)
Set the projection evaluator. This class is able to compute the projection of a given state.

void setProjectionEvaluator (const std::string &name)
Set the projection evaluator (select one from the ones registered with the state space).

const base::ProjectionEvaluatorPtrgetProjectionEvaluator () const
Get the projection evaluator.

void setRange (double distance)
Set the range the planner is supposed to use. More...

double getRange () const
Get the range the planner is using.

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.

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. 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.

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

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).

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.

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().

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 Types

typedef Grid< MotionInfo >::Cell GridCell
A grid cell.

typedef PDF< GridCell * > CellPDF
A PDF of grid cells.

## Protected Member Functions

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

void freeGridMotions (Grid< MotionInfo > &grid)
Free the memory used by the motions contained in a grid.

void addMotion (TreeData &tree, Motion *motion)
Add a motion to a tree.

MotionselectMotion (TreeData &tree)
Select a motion from a tree.

void removeMotion (TreeData &tree, Motion *motion)
Remove a motion from a tree.

bool isPathValid (TreeData &tree, Motion *motion)
Since solutions are computed in a lazy fashion, once trees are connected, the solution found needs to be checked for validity. This function checks whether the reverse path from a given motion to a root is valid. If this is not the case, invalid motions are removed.

bool checkSolution (bool start, TreeData &tree, TreeData &otherTree, Motion *motion, std::vector< Motion *> &solution)
Check if a solution can be obtained by connecting two trees using a specified motion.

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_
The employed state sampler.

base::ProjectionEvaluatorPtr projectionEvaluator_
The employed projection evaluator.

TreeData tStart_
The start tree.

TreeData tGoal_
The goal tree.

double maxDistance_ {0.}
The maximum length of a motion to be added in the tree.

RNG rng_
The random number generator to be used.

std::pair< base::State *, base::State * > connectionPoint_ {nullptr, nullptr}
The pair of states in each tree connected during planning. Used for PlannerData computation.

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.

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.

## Detailed Description

Single-Query Bi-Directional Probabilistic Roadmap Planner with Lazy Collision Checking.

Short description
SBL is a tree-based motion planner that attempts to grow two trees at once: one grows from the starting state and the other from the goal state. The tree expansion strategy is the same as for EST. Attempts are made to connect these trees at every step of the expansion. If they are connected, a solution path is obtained. However, this solution path is not certain to be valid (the lazy part of the algorithm) so it is checked for validity. If invalid parts are found, they are removed from the tree and exploration of the state space continues until a solution is found. To guide the exploration, an additional grid data structure is maintained. Grid cells contain states that have been previously visited. When deciding which state to use for further expansion, this grid is used; least-filled grid cells have most chances of being selected. The grid is usually imposed on a projection of the state space. This projection needs to be set before using the planner (setProjectionEvaluator() function). Connection of states in different trees is attempted if they fall in the same grid cell. If no projection is set, the planner will attempt to use the default projection associated to the state space. An exception is thrown if no default projection is available either.
External documentation
G. Sánchez and J.-C. Latombe, A single-query bi-directional probabilistic roadmap planner with lazy collision checking, in The Tenth International Symposium on Robotics Research, pp. 403–417, 2001. DOI: 10.1007/3-540-36460-9_27
[PDF]

Definition at line 84 of file SBL.h.

## ◆ setRange()

 void ompl::geometric::SBL::setRange ( double distance )
inline

Set the range the planner is supposed to use.

This parameter greatly influences the runtime of the algorithm. It represents the maximum length of a motion to be added in the tree of motions.

Definition at line 117 of file SBL.h.

The documentation for this class was generated from the following files:
• ompl/geometric/planners/sbl/SBL.h
• ompl/geometric/planners/sbl/src/SBL.cpp