base::DubinsStateSpace Class Reference

An SE(2) state space where distance is measured by the length of Dubins curves. More...

#include <ompl/base/spaces/DubinsStateSpace.h>

Inheritance diagram for base::DubinsStateSpace:

List of all members.

Public Types

enum  DubinsPathSegmentType { DUBINS_LEFT = 0, DUBINS_STRAIGHT = 1, DUBINS_RIGHT = 2 }
 The Dubins path segment type.

Public Member Functions

 DubinsStateSpace (double turningRadius=1.0, bool isSymmetric=false)
virtual bool isMetricSpace () const
 Return true if the distance function associated with the space is a metric.
virtual double distance (const State *state1, const State *state2) const
 Computes distance between two states. This function satisfies the properties of a metric if isMetricSpace() is true, and its return value will always be between 0 and getMaximumExtent()
virtual void interpolate (const State *from, const State *to, const double t, State *state) const
 Computes the state that lies at time t in [0, 1] on the segment that connects from state to to state. The memory location of state is not required to be different from the memory of either from or to.
virtual void interpolate (const State *from, const State *to, const double t, bool &firstTime, DubinsPath &path, State *state) const
virtual bool hasSymmetricDistance () const
 Check if the distance function on this state space is symmetric, i.e. distance(s1,s2) = distance(s2,s1). Default implementation returns true.
virtual bool hasSymmetricInterpolate () const
 Check if the interpolation function on this state space is symmetric, i.e. interpolate(from, to, t, state) = interpolate(to, from, 1-t, state). Default implementation returns true.
virtual void sanityChecks () const
 Convenience function that allows derived state spaces to choose which checks should pass (see SanityChecks flags) and how strict the checks are. This just calls sanityChecks() with some default arguments.
DubinsPath dubins (const State *state1, const State *state2) const
 Return the shortest Dubins path from SE(2) state state1 to SE(2) state state2.

Static Public Attributes

static const DubinsPathSegmentType dubinsPathType [6][3]
 Dubins path types.

Protected Member Functions

virtual void interpolate (const State *from, const DubinsPath &path, const double t, State *state) const

Protected Attributes

double rho_
 Turning radius.
bool isSymmetric_
 Whether the distance is "symmetrized".

Detailed Description

An SE(2) state space where distance is measured by the length of Dubins curves.

Note that this Dubins distance is not a proper distance metric, so nearest neighbor methods that rely on distance() being a metric (such as ompl::NearestNeighborsGNAT) will not always return the true nearest neighbors or get stuck in an infinite loop.

The notation and solutions in the code are taken from:
A.M. Shkel and V. Lumelsky, “Classification of the Dubins set,” Robotics and Autonomous Systems, 34(4):179-202, 2001. DOI: 10.1016/S0921-8890(00)00127-5

The classification scheme described there is not actually used, since it only applies to “long” paths.

Definition at line 65 of file DubinsStateSpace.h.


Member Data Documentation

const ompl::base::DubinsStateSpace::DubinsPathSegmentType base::DubinsStateSpace::dubinsPathType [static]
Initial value:
 {
    { DUBINS_LEFT, DUBINS_STRAIGHT, DUBINS_LEFT },
    { DUBINS_RIGHT, DUBINS_STRAIGHT, DUBINS_RIGHT },
    { DUBINS_RIGHT, DUBINS_STRAIGHT, DUBINS_LEFT },
    { DUBINS_LEFT, DUBINS_STRAIGHT, DUBINS_RIGHT },
    { DUBINS_RIGHT, DUBINS_LEFT, DUBINS_RIGHT },
    { DUBINS_LEFT, DUBINS_RIGHT, DUBINS_LEFT }
}

Dubins path types.

Definition at line 72 of file DubinsStateSpace.h.

Whether the distance is "symmetrized".

If true the distance from state s1 to state s2 is the same as the distance from s2 to s1. This is done by taking the minimum length of the Dubins curves that connect s1 to s2 and s2 to s1. If isSymmetric_ is true, then the distance no longer satisfies the triangle inequality.

Definition at line 155 of file DubinsStateSpace.h.


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