Kinodynamic Planning by Interior-Exterior Cell Exploration. More...
#include <KPIECE1.h>
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. | |
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. | |
void | setGoalBias (double goalBias) |
double | getGoalBias (void) 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 (void) 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]. | |
double | getGoodCellScoreFactor (void) const |
Get the factor that is multiplied to a cell's score if extending a motion from that cell succeeded. | |
double | getBadCellScoreFactor (void) const |
Get the factor that is multiplied to a cell's score if extending a motion from that cell failed. | |
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. | |
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 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 GridB< CellData *, OrderCellsByImportance > | Grid |
The datatype for the maintained grid datastructure. | |
Protected Member Functions | |
void | freeMemory (void) |
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. | |
Grid::Cell * | addMotion (Motion *motion, double dist) |
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. | |
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 SpaceInformation * | siC_ |
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_ |
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. | |
double | badScoreFactor_ |
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_ |
double | selectBorderFraction_ |
The fraction of time to focus exploration on the border of the grid. | |
double | goalBias_ |
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. |
Kinodynamic Planning by Interior-Exterior Cell Exploration.
@par 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. @par External documentation I.A. Şucan and L.E. Kavraki, Kinodynamic motion planning by interior-exterior cell exploration, in <em>Workshop on the Algorithmic Foundations of Robotics</em>, Dec. 2008.<br> <a href="http://ioan.sucan.ro/files/pubs/wafr2008.pdf">[PDF]</a>
double ompl::control::KPIECE1::getGoalBias | ( | void | ) | const [inline] |
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.