Class BiEST

Nested Relationships

Nested Types

Inheritance Relationships

Base Type

Class Documentation

class BiEST : public ompl::base::Planner

Bi-directional Expansive Space Trees.

Short description

EST is a tree-based motion planner that attempts to detect the less explored area of the space by measuring the density of the explored space, biasing exploration toward parts of the space with lowest density.

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[PDF]

Public Functions

BiEST(const base::SpaceInformationPtr &si)

Constructor.

~BiEST() override
virtual 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). If clearQuery() is called, the planner may retain prior datastructures generated from a previous query on a new problem definition. The function terminates if the call to ptc returns true.

virtual void clear() override

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

inline void setRange(double distance)

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.

inline double getRange() const

Get the range the planner is using.

virtual 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.

virtual 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).

Protected Functions

inline double distanceFunction(const Motion *a, const Motion *b) const

Compute distance between motions (actually distance between contained states)

void freeMemory()

Free the memory allocated by this planner.

void addMotion(Motion *motion, std::vector<Motion*> &motions, PDF<Motion*> &pdf, const std::shared_ptr<NearestNeighbors<Motion*>> &nn, const std::vector<Motion*> &neighbors)

Add a motion to the exploration tree.

Protected Attributes

std::shared_ptr<NearestNeighbors<Motion*>> nnStart_

A nearest-neighbors datastructure containing the tree of motions.

std::shared_ptr<NearestNeighbors<Motion*>> nnGoal_
std::vector<Motion*> startMotions_

The set of all states in the start tree.

std::vector<Motion*> goalMotions_
PDF<Motion*> startPdf_

The probability distribution function over states in each tree.

PDF<Motion*> goalPdf_
base::ValidStateSamplerPtr sampler_

Valid state sampler.

double maxDistance_ = {0.0}

The maximum length of a motion to be added to a tree.

double nbrhoodRadius_

The radius considered for neighborhood.

RNG rng_

The random number generator.

std::pair<base::State*, base::State*> connectionPoint_ = {nullptr, nullptr}

The pair of states in each tree connected during planning. Used for PlannerData computation.

class Motion

The definition of a motion.

Public Functions

Motion() = default
inline Motion(const base::SpaceInformationPtr &si)

Constructor that allocates memory for the state.

~Motion() = default

Public Members

base::State *state = {nullptr}

The state contained by the motion.

Motion *parent = {nullptr}

The parent motion in the exploration tree.

PDF<Motion*>::Element *element = {nullptr}

A pointer to the corresponding element in the probability distribution function.

const base::State *root = {nullptr}

The root node of the tree this motion is in.