ompl::geometric::EST Class Reference

Expansive Space Trees. More...

#include <ompl/geometric/planners/est/EST.h>

Inheritance diagram for ompl::geometric::EST:

List of all members.

Classes

class  Motion
 The definition of a motion. More...
struct  MotionInfo
 A struct containing an array of motions and a corresponding PDF element. More...
struct  TreeData
 The data contained by a tree of exploration. More...

Public Member Functions

 EST (const base::SpaceInformationPtr &si)
 Constructor.
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.
virtual void clear ()
 Clear all internal datastructures. Planner settings are not affected. Subsequent calls to solve() will ignore all previous work.
void setGoalBias (double goalBias)
 In the process of randomly selecting states in the state space to attempt to go towards, the algorithm may in fact choose the actual goal state, if it knows it, with some probability. This probability is a real number between 0.0 and 1.0; its value should usually be around 0.05 and should not be too large. It is probably a good idea to use the default value.
double getGoalBias () const
 Get the goal bias the planner is using.
void setRange (double distance)
 Set the range the planner is supposed to use.
double getRange () const
 Get the range the planner is using.
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::ProjectionEvaluatorPtr
getProjectionEvaluator () const
 Get the projection evaluator.
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 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).

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 this planner.
void addMotion (Motion *motion)
 Add a motion to the exploration tree.
MotionselectMotion ()
 Select a motion to continue the expansion of the tree from.

Protected Attributes

base::ValidStateSamplerPtr sampler_
 Valid state sampler.
TreeData tree_
 The exploration tree constructed by this algorithm.
base::ProjectionEvaluatorPtr projectionEvaluator_
 This algorithm uses a discretization (a grid) to guide the exploration. The exploration is imposed on a projection of the state space.
double goalBias_
 The fraction of time the goal is picked as the state to expand towards (if such a state is available)
double maxDistance_
 The maximum length of a motion to be added to a tree.
RNG rng_
 The random number generator.
CellPDF pdf_
 The PDF used for selecting a cell from which to sample a motion.
MotionlastGoalMotion_
 The most recent goal motion. Used for PlannerData computation.

Detailed Description

Expansive Space Trees.

Short description
EST is a tree-based motion planner that attempts to detect the less explored area of the space through the use of a grid imposed on a projection of the state space. Using this information, EST continues tree expansion primarily from less explored areas. It is important to set the projection the algorithm uses (setProjectionEvaluator() function). 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
D. Hsu, J.-C. Latombe, and R. Motwani, Path planning in expansive configuration spaces, Intl. J. Computational Geometry and Applications, vol. 9, no. 4-5, pp. 495–512, 1999. DOI: [10.1142/S0218195999000285](http://dx.doi.org/10.1142/S0218195999000285)
[[PDF]](http://bigbird.comp.nus.edu.sg/pmwiki/farm/motion/uploads/Site/ijcga96.pdf)

Definition at line 73 of file EST.h.


Member Function Documentation

void ompl::geometric::EST::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 109 of file EST.h.


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