ompl::control::KPIECE1 Class Reference

Kinodynamic Planning by Interior-Exterior Cell Exploration. More...

#include <ompl/control/planners/kpiece/KPIECE1.h>

Inheritance diagram for ompl::control::KPIECE1:

## Classes

struct  CellData
The data held by a cell in the grid of motions. More...

struct  CloseSample
Information about a known good sample (closer to the goal than others) More...

struct  CloseSamples
Bounded set of good samples. More...

struct  Motion
Representation of a motion for this algorithm. More...

struct  OrderCellsByImportance
Definintion of an operator passed to the Grid structure, to order cells by importance. More...

struct  TreeData
The data defining a tree of motions for this algorithm. More...

## Public Member Functions

KPIECE1 (const SpaceInformationPtr &si)
Constructor.

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.

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

void setGoalBias (double goalBias)

double getGoalBias () const

void setBorderFraction (double bp)
Set the fraction of time for focusing on the border (between 0 and 1). This is the minimum fraction used to select cells that are exterior (minimum because if 95% of cells are on the border, they will be selected with 95% chance, even if this fraction is set to 90%)

double getBorderFraction () const
Get the fraction of time to focus exploration on boundary.

void setCellScoreFactor (double good, double bad)
When extending a motion from a cell, the extension can be successful or it can fail. If the extension is successful, the score of the cell is multiplied by good. If the extension fails, the score of the cell is multiplied by bad. These numbers should be in the range (0, 1].

Set the factor that is to be applied to a cell's score when an expansion from that cell fails.

void setGoodCellScoreFactor (double good)
Set the factor that is to be applied to a cell's score when an expansion from that cell succeedes.

double getGoodCellScoreFactor () const
Get the factor that is multiplied to a cell's score if extending a motion from that cell succeeded.

Get the factor that is multiplied to a cell's score if extending a motion from that cell failed.

void setMaxCloseSamplesCount (unsigned int nCloseSamples)
When motions reach close to the goal, they are stored in a separate queue to allow biasing towards the goal. This function sets the maximum size of that queue.

unsigned int getMaxCloseSamplesCount () const
Get the maximum number of samples to store in the queue of samples that are close to the goal.

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.

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.

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.

ProblemDefinitionPtrgetProblemDefinition ()
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() or clearQuery().

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.

virtual void clearQuery ()
Clears internal datastructures of any query-specific information from the previous query. Planner settings are not affected. The planner, if able, should retain all datastructures generated from previous queries that can be used to help solve the next query. Note that clear() should also clear all query-specific information along with all other datastructures in the planner. By default clearQuery() calls clear().

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

using Grid = GridB< CellData *, OrderCellsByImportance >
The datatype for the maintained grid datastructure.

## Protected Member Functions

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

void freeGridMotions (Grid &grid)
Free the memory for the motions contained in a grid.

void freeCellData (CellData *cdata)
Free the memory for the data contained in a grid cell.

void freeMotion (Motion *motion)
Free the memory for a motion.

Add a motion to the grid containing motions. As a hint, dist specifies the distance to the goal from the state of the motion being added. The function Returns the number of cells created to accommodate the new motion (0 or 1).

bool selectMotion (Motion *&smotion, Grid::Cell *&scell)
Select a motion and the cell it is part of from the grid of motions. This is where preference is given to cells on the boundary of the grid.

unsigned int findNextMotion (const std::vector< Grid::Coord > &coords, unsigned int index, unsigned int count)
When generated motions are to be added to the tree of motions, they often need to be split, so they don't cross cell boundaries. Given that a motion starts out in the cell origin and it crosses the cells in coords[index] through coords[last] (inclusively), return the index of the state to be used in the next part of the motion (that is within a cell). This will be a value between index and last.

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.

## Static Protected Member Functions

static void computeImportance (Grid::Cell *cell, void *)
This function is provided as a calback to the grid datastructure to update the importance of a cell.

## Protected Attributes

ControlSamplerPtr controlSampler_
A control sampler.

TreeData tree_
The tree datastructure.

const SpaceInformationsiC_
The base::SpaceInformation cast as control::SpaceInformation, for convenience.

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 goodScoreFactor_ {0.9}
When extending a motion from a cell, the extension can be successful. If it is, the score of the cell is multiplied by this factor.

When extending a motion from a cell, the extension can fail. If it is, the score of the cell is multiplied by this factor.

unsigned int nCloseSamples_ {30}
When motions reach close to the goal, they are stored in a separate queue to allow biasing towards the goal. This variable specifies the maximum number of samples to keep in that queue.

double selectBorderFraction_ {0.8}
The fraction of time to focus exploration on the border of the grid.

double goalBias_ {0.05}
The fraction of time the goal is picked as the state to expand towards (if such a state is available)

RNG rng_
The random number generator.

MotionlastGoalMotion_ {nullptr}
The most recent goal motion. 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
using PlannerProgressProperty = std::function< std::string()>
Definition of a function which returns a property about the planner's progress that can be queried by a benchmarking routine.

using PlannerProgressProperties = std::map< std::string, PlannerProgressProperty >
A dictionary which maps the name of a progress property to the function to be used for querying that property.

## Detailed Description

Kinodynamic Planning by Interior-Exterior Cell Exploration.

Short description
KPIECE is a tree-based planner that uses a discretization (multiple levels, in general) to guide the exploration of the continuous space. This implementation is a simplified one, using a single level of discretization: one grid. The grid is imposed on a projection of the state space. When exploring the space, preference is given to the boundary of this grid. The boundary is computed to be the set of grid cells that have less than 2n non-diagonal neighbors in an n-dimensional projection space. 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. This implementation is intended for systems with differential constraints.
External documentation
I.A. Şucan and L.E. Kavraki, Kinodynamic motion planning by interior-exterior cell exploration, in Workshop on the Algorithmic Foundations of Robotics, Dec. 2008.
[PDF]

Definition at line 136 of file KPIECE1.h.

## ◆ getGoalBias()

 double ompl::control::KPIECE1::getGoalBias ( ) const
inline

Get the goal bias the planner is using

Definition at line 192 of file KPIECE1.h.

## ◆ setGoalBias()

 void ompl::control::KPIECE1::setGoalBias ( double goalBias )
inline

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 186 of file KPIECE1.h.

The documentation for this class was generated from the following files: