driving.Path

Planned vehicle path

Description

The driving.Path object represents a vehicle path composed of a sequence of path segments. These segments can be either driving.DubinsPathSegment objects or driving.ReedsSheppPathSegment objects and are stored in the PathSegments property of driving.Path.

To check the validity of the path against a vehicleCostmap object, use the checkPathValidity function. To interpolate poses along the length of the path, use the interpolate function.

Creation

To create a driving.Path object, use the plan function, specifying a pathPlannerRRT object as input.

Properties

StartPose — Initial pose of vehicle

[x, y, Θ] vector

This property is read-only.

Initial pose of the vehicle, specified as an [x, y, Θ] vector. x and y are in world units, such as meters. Θ is in degrees.

GoalPose — Goal pose of vehicle

[x, y, Θ] vector

This property is read-only.

Goal pose of the vehicle, specified as an [x, y, Θ] vector. x and y are in world units, such as meters. Θ is in degrees.

PathSegments — Segments along path

array of driving.DubinsPathSegment objects | array of driving.ReedsSheppPathSegment objects

This property is read-only.

Segments along the path, specified as an array of driving.DubinsPathSegment objects or driving.ReedsSheppPathSegment objects.

Length — Length of path

positive real scalar

This property is read-only.

Length of the path, in world units, specified as a positive real scalar.

Object Functions

interpolate	Interpolate poses along planned vehicle path
plot	Plot planned vehicle path

Examples

Plan Path and Check Its Validity

Plan a vehicle path through a parking lot by using the optimal rapidly exploring random tree (RRT*) algorithm. Check that the path is valid, and then plot the transition poses along the path.

Load a costmap of a parking lot. Plot the costmap to see the parking lot and inflated areas for the vehicle to avoid.

data = load('parkingLotCostmap.mat');
costmap = data.parkingLotCostmap;
plot(costmap)

Define start and goal poses for the vehicle as [x, y, Θ] vectors. World units for the (x,y) locations are in meters. World units for the Θ orientation angles are in degrees.

startPose = [4, 4, 90]; % [meters, meters, degrees]
goalPose = [30, 13, 0];

Use a pathPlannerRRT object to plan a path from the start pose to the goal pose.

planner = pathPlannerRRT(costmap);
refPath = plan(planner,startPose,goalPose);

Check that the path is valid.

isPathValid = checkPathValidity(refPath,costmap)

isPathValid = logical
   1

Interpolate the transition poses along the path.

transitionPoses = interpolate(refPath);

Plot the planned path and the transition poses on the costmap.

hold on
plot(refPath,'DisplayName','Planned Path')
scatter(transitionPoses(:,1),transitionPoses(:,2),[],'filled', ...
    'DisplayName','Transition Poses')
hold off

Plan Path and Interpolate Along Path

Plan a vehicle path through a parking lot by using the rapidly exploring random tree (RRT*) algorithm. Interpolate the poses of the vehicle at points along the path.

Load a costmap of a parking lot. Plot the costmap to see the parking lot and inflated areas for the vehicle to avoid.

data = load('parkingLotCostmap.mat');
costmap = data.parkingLotCostmap;
plot(costmap)

Define start and goal poses for the vehicle as [x, y, Θ] vectors. World units for the (x,y) locations are in meters. World units for the Θ orientation angles are in degrees.

startPose = [4, 4, 90]; % [meters, meters, degrees]
goalPose = [30, 13, 0]; 

Use a pathPlannerRRT object to plan a path from the start pose to the goal pose.

planner = pathPlannerRRT(costmap);
refPath = plan(planner,startPose,goalPose);

Interpolate the vehicle poses every 1 meter along the entire path.

lengths = 0 : 1 : refPath.Length;
poses = interpolate(refPath,lengths);

Plot the interpolated poses on the costmap.

plot(costmap)
hold on
scatter(poses(:,1),poses(:,2),'DisplayName','Interpolated Poses')
hold off

Extended Capabilities

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

Version History

Introduced in R2018a

R2018b: connectingPoses function and driving.Path object properties KeyPoses and NumSegments are not recommended

The connectingPoses function and the KeyPoses and NumSegments properties of the driving.Path object are not recommended. Instead, use the interpolate function, which returns key poses, connecting poses, transition poses, and direction changes. The KeyPoses and NumSegments properties are no longer relevant. KeyPoses, NumSegments, and connectingPoses will be removed in a future release.

In R2018a, connectingPoses enabled you to obtain intermediate poses either along the entire path or along the path segments that are between key poses (as specified by KeyPoses). Using the interpolate function, you can now obtain intermediate poses at any specified point along the path. The interpolate function also provides transition poses at which changes in direction occur.

Update Code

Remove all instances of KeyPoses and NumSegments and replace all instances of connectingPoses with interpolate. The table shows typical usages of connectingPoses and how to update your code to use interpolate instead. Here, path is a driving.Path object returned by pathPlannerRRT.

Discouraged Usage	Recommended Replacement
poses = connectingPoses(path);	poses = interpolate(path);
segID = 1; posesSegment = connectingPoses(path,segID);	interpolate does not have a direct syntax for obtaining segment poses. However, you can sample poses of a segment using a specified step time. For example: step = 0.1; samples = 0 : step : path.PathSegments(1).Length; segmentPoses = interpolate(path,samples);