reedsSheppPathSegment

Reeds-Shepp path segment connecting two poses

Description

The reedSheppPathSegment object holds information for a Reeds-Shepp path segment to connect between poses. A Reeds-Shepp path segment connects two poses as a sequence of five motion types. The motion options are:

• Straight

• Left turn at maximum steer

• Right turn at maximum steer

• No movement

Creation

To generate a reedSheppPathSegment object, use the connect function with a reedsSheppConnection object:

reedsPathSegObj = connect(connectionObj,start,goal) connects the start and goal poses using the specified connection type object.

To specifically define a path segment:

reedsPathSegObj = reedsSheppPathSegment(connectionObj,start,goal,motionLengths,motionTypes) specifies the Reeds-Shepp connection type, the start and goal poses, and the corresponding motion lengths and types. These values are set to the corresponding properties in the object.

Properties

MinTurningRadius — Minimum turning radius of vehicle

positive scalar

This property is read-only.

Minimum turning radius of the vehicle, specified as a positive scalar in meters. This value corresponds to the radius of the turning circle at the maximum steering angle of the vehicle.

Data Types: double

StartPose — Initial pose of vehicle

[x, y, Θ] vector

This property is read-only.

Initial pose of the vehicle at the start of the path segment, specified as an [x, y, Θ] vector. x and y are in meters. Θ is in radians.

Data Types: double

GoalPose — Goal pose of vehicle

[x, y, Θ] vector

This property is read-only.

Goal pose of the vehicle at the end of the path segment, specified as an [x, y, Θ] vector. x and y are in meters. Θ is in radians.

Data Types: double

MotionLengths — Length of each motion

five-element numeric vector

This property is read-only.

Length of each motion in the path segment, specified as a five-element numeric vector in meters. Each motion length corresponds to a motion type specified in MotionTypes.

Data Types: double

MotionTypes — Type of each motion

five-element string cell array

This property is read-only.

Type of each motion in the path segment, specified as a five-element string cell array.

Motion Type	Description
"S"	Straight (forward, p or reverse, n)
"L"	Left turn at the maximum steering angle of the vehicle (forward, p or reverse, n)
"R"	Right turn at the maximum steering angle of the vehicle (forward, p or reverse, n)
"N"	No motion

If a path segment has fewer than five motion types, the remaining elements are "N" (no motion).

Example: {"L","S","R","L","R"}

Data Types: cell

MotionDirections — Direction of each motion

five-element vector of 1s (forward motion) and –1s (reverse motion)

This property is read-only.

Direction of each motion in the path segment, specified as a five-element vector of 1s (forward motion) and –1s (reverse motion). Each motion direction corresponds to a motion length specified in MotionLengths and a motion type specified in MotionTypes.

When no motion occurs, that is, when a MotionTypes value is "N", then the corresponding MotionDirections element is 1.

Example: [-1 1 -1 1 1]

Data Types: double

Length — Length of path segment

positive scalar

This property is read-only.

Length of the path segment, specified as a positive scalar in meters. This length is just a sum of the elements in MotionLengths.

Data Types: double

Object Functions

interpolate	Interpolate poses along path segment
show	Visualize path segment

Examples

Connect Poses Using ReedsShepp Connection Path

Create a reedsSheppConnection object.

reedsConnObj = reedsSheppConnection;

Define start and goal poses as [x y theta] vectors.

startPose = [0 0 0];
goalPose = [1 1 pi];

Calculate a valid path segment to connect the poses.

[pathSegObj,pathCosts] = connect(reedsConnObj,startPose,goalPose);

Show the generated path.

show(pathSegObj{1})

References

[1] Reeds, J. A., and L. A. Shepp. "Optimal Paths for a Car That Goes Both Forwards and Backwards." Pacific Journal of Mathematics. Vol. 145, Number 2, 1990, pp. 367–393.

Extended Capabilities

C/C++ Code Generation
Generate C and C++ code using MATLAB® Coder™.

Version History

Introduced in R2019b