ompl::geometric::LazyRRT Class Reference

#include <LazyRRT.h>

Inheritance diagram for ompl::geometric::LazyRRT:

Classes
class	Motion
	Representation of a motion. More...
Public Member Functions
virtual void	clear (void)
	Clear all internal datastructures. Planner settings are not affected. Subsequent calls to solve() will ignore all previous work.
double	getGoalBias (void) const
	Get the goal bias the planner is using.
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).
double	getRange (void) const
	Get the range the planner is using.
	LazyRRT (const base::SpaceInformationPtr &si)
	Constructor.
void	setGoalBias (double goalBias)
	Set the goal biasing.
template<template< typename T > class NN>
void	setNearestNeighbors (void)
	Set a different nearest neighbors datastructure.
void	setRange (double distance)
	Set the range the planner is supposed to use.
virtual void	setup (void)
	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 bool	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 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	~LazyRRT (void)
Protected Member Functions
double	distanceFunction (const Motion a, const Motion b) const
	Compute distance between motions (actually distance between contained states).
void	freeMemory (void)
	Free the memory allocated by this planner.
void	removeMotion (Motion *motion)
	Remove a motion from the tree datastructure.
Protected Attributes
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.
boost::shared_ptr < NearestNeighbors< Motion * > >	nn_
	A nearest-neighbors datastructure containing the tree of motions.
RNG	rng_
	The random number generator.
base::StateSamplerPtr	sampler_
	State sampler.

Detailed Description

Lazy RRT.

Short description: RRT is a tree-based motion planner that uses the following idea: RRT samples a random state qr in the state space, then finds the state qc among the previously seen states that is closest to qr and expands from qc towards qr, until a state qm is reached. qm is then added to the exploration tree. The difference between RRT and LazyRRT is that when moving towards the new state qm, LazyRRT does not check to make sure the path is valid. Instead, it is optimistic and attempts to find a path as soon as possible. Once a path is found, it is checked for collision. If collisions are found, the invalid path segments are removed and the search process is continued.

External documentation

J. Kuffner and S.M. LaValle, RRT-connect: An efficient approach to single-query path planning, in Proc. 2000 IEEE Intl. Conf. on Robotics and Automation, pp. 995–1001, Apr. 2000. DOI: 10.1109/ROBOT.2000.844730
[PDF] [more]
R. Bohlin and L.E. Kavraki, A Randomized Algorithm for Robot Path Planning Based on Lazy Evaluation, in Handbook on Randomized Computing, pp. 221–249, 2001.
[PDF]
R. Bohlin and L.E. Kavraki, Path planning using lazy PRM, in Proc. 2000 IEEE Intl. Conf. on Robotics and Automation, pp. 521–528, 2000. DOI: 10.1109/ROBOT.2000.844107
[PDF]

Definition at line 81 of file LazyRRT.h.

Constructor & Destructor Documentation

ompl::geometric::LazyRRT::LazyRRT ( const base::SpaceInformationPtr & si ) [inline]

Constructor.

Definition at line 86 of file LazyRRT.h.

virtual ompl::geometric::LazyRRT::~LazyRRT ( void ) [inline, virtual]

Definition at line 94 of file LazyRRT.h.

Member Function Documentation

virtual void ompl::geometric::LazyRRT::clear ( void ) [virtual]

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

Reimplemented from ompl::base::Planner.

double ompl::geometric::LazyRRT::distanceFunction	(	const Motion *	a,
		const Motion *	b
	)			const `[inline, protected]`

Compute distance between motions (actually distance between contained states).

Definition at line 190 of file LazyRRT.h.

void ompl::geometric::LazyRRT::freeMemory ( void ) [protected]

Free the memory allocated by this planner.

double ompl::geometric::LazyRRT::getGoalBias ( void ) const [inline]

Get the goal bias the planner is using.

Definition at line 120 of file LazyRRT.h.

virtual void ompl::geometric::LazyRRT::getPlannerData ( base::PlannerData & data ) const [virtual]

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).

Reimplemented from ompl::base::Planner.

double ompl::geometric::LazyRRT::getRange ( void ) const [inline]

Get the range the planner is using.

Definition at line 136 of file LazyRRT.h.

void ompl::geometric::LazyRRT::removeMotion ( Motion * motion ) [protected]

Remove a motion from the tree datastructure.

void ompl::geometric::LazyRRT::setGoalBias ( double goalBias ) [inline]

Set the goal biasing.

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.

Definition at line 114 of file LazyRRT.h.

template<template< typename T > class NN>

void ompl::geometric::LazyRRT::setNearestNeighbors ( void ) [inline]

Set a different nearest neighbors datastructure.

Definition at line 143 of file LazyRRT.h.

void ompl::geometric::LazyRRT::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 130 of file LazyRRT.h.

virtual void ompl::geometric::LazyRRT::setup ( void ) [virtual]

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.

Reimplemented from ompl::base::Planner.

virtual bool ompl::geometric::LazyRRT::solve ( const base::PlannerTerminationCondition & ptc ) [virtual]

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 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.

Implements ompl::base::Planner.