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

#include <SBL.h>

Inheritance diagram for ompl::geometric::SBL:

List of all members.

Classes

class  Motion
 Representation of a motion. 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::ProjectionEvaluatorPtr
getProjectionEvaluator (void) const
 Get the projection evaluator.
void setRange (double distance)
 Set the range the planner is supposed to use.
double getRange (void) const
 Get the range the planner is using.
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 void clear (void)
 Clear all internal datastructures. Planner settings are not affected. Subsequent calls to solve() will ignore all previous work.
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 std::vector< Motion * > MotionSet
 An array of motions.

Protected Member Functions

void freeMemory (void)
 Free the memory allocated by the planner.
void freeGridMotions (Grid< MotionSet > &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 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_
 The maximum length of a motion to be added in the tree.
RNG rng_
 The random number generator to be used.

Detailed Description

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

      @par 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 \ref gEST "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.

      @par External documentation
      G. Sánchez and J.-C. Latombe, A single-query bi-directional probabilistic roadmap planner with lazy collision checking, in <em>The Tenth International Symposium on Robotics Research</em>, pp. 403–417, 2001.
      DOI: <a href="http://dx.doi.org/10.1007/3-540-36460-9_27">10.1007/3-540-36460-9_27</a><br>
      <a href="http://www.springerlink.com/content/9843341054386hh6/fulltext.pdf">[PDF]</a>

Definition at line 86 of file SBL.h.


Member Function Documentation

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 127 of file SBL.h.


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