lanespec

Create road lane specifications

Description

The lanespec object defines the lane specifications of a road that was added to a drivingScenario object using the road function. For more details, see Lane Specifications.

Creation

Syntax

lnspec = lanespec(numlanes)

lnspec = lanespec(numlanes,Name,Value)

Description

lnspec = lanespec(numlanes) creates lane specifications for a road having numlanes lanes. numLanes sets the NumLanes property of the lanespec object. The order for numbering the lanes on a road depend on the orientation of the road. For more details, see Draw Direction of Road and Numbering of Lanes.

lnspec = lanespec(numlanes,Name,Value) sets properties using one or more name-value pairs. For example, lanespec(3,'Width',[2.25 3.5 2.25]) specifies a three-lane road with widths from left to right of 2.25 meters, 3.5 meters, and 2.25 meters. For more information on the geometrical properties of a lane, see Lane Specifications.

Properties

NumLanes — Number of lanes in road

positive integer | two-element vector of positive integers

This property is read-only.

Number of lanes in the road, specified as a positive integer or two-element vector of positive integers, [N_L, N_R]. When NumLanes is a positive integer, all lanes flow in the same direction. When NumLanes is a vector:

• N_L is the number of left lanes, all flowing in one direction.

• N_R is the number of right lanes, all flowing in the opposite direction.

The total number of lanes in the road is the sum of these vector values: N = N_L + N_R.

You can set this property when you create the object. After you create the object, this property is read-only.

Example: [2 2] specifies two left lanes and two right lanes.

Width — Lane widths

3.6 (default) | positive real scalar | 1-by-N vector of positive real scalars

Lane widths, specified as a positive real scalar or 1-by-N vector of positive real scalars, where N is the number of lanes in the road. N must be equal to numlanes and the corresponding value set in the NumLanes property.

When Width is a scalar, the same value is applied to all lanes. When Width is a vector, the vector elements apply to lanes from left to right. Units are in meters.

Example: [3.5 3.7 3.7 3.5]

Data Types: double

Marking — Lane markings

LaneMarking object (default) | SolidMarking object | DashedMarking object | CompoundMarking object | 1-by-M array of lane marking objects

Lane markings of road, specified as one of these values:

• LaneMarking object. This is the default.

• SolidMarking object

• DashedMarking object

• CompoundMarking object

• 1-by-M array of lane marking objects.

M is the number of lane markings. For a road with N lanes, M = N + 1.

To create lane marking objects, use the laneMarking function and specify the type of lane marking.

'Unmarked'	'Solid'	'Dashed'	'DoubleSolid'	'DoubleDashed'	'SolidDashed'	'DashedSolid'
No lane marking	Solid line	Dashed line	Two solid lines	Two dashed lines	Solid line on left, dashed line on right	Dashed line on left, solid line on right

By default, for a one-way road, the rightmost and center lane markings are white and the leftmost lane marking is yellow. For two-way roads, the color of the dividing lane marking is yellow.

Example: [laneMarking('Solid') laneMarking('DoubleDashed') laneMarking('Solid')] specifies lane markings for a two-lane road. The leftmost and rightmost lane markings are solid lines, and the dividing lane marking is a double-dashed line.

Type — Lane types

DrivingLaneType object (default) | RestrictedLaneType object | ShoulderLaneType object | ParkingLaneType object | 1-by-M array of lane type objects

Lane types of road, specified as a homogeneous lane type object or a 1-by-M array of lane type objects. M is the number of lane types.

To create lane type objects, use the laneType function and specify the type of lane.

'Driving'	'Border'	'Restricted'	'Shoulder'	'Parking'

Example: [laneType('Shoulder') laneType('Driving')] specifies the lane types for a two-lane road. The leftmost lane is the shoulder lane and the rightmost lane is the driving lane.

Examples

Create Straight Four-Lane Road

Create a driving scenario and the road centers for a straight, 80-meter road.

scenario = drivingScenario;
roadCenters = [0 0; 80 0];

Create a lanespec object for a four-lane road. Use the laneMarking function to specify its five lane markings. The center line is double-solid and double yellow. The outermost lines are solid and white. The inner lines are dashed and white.

solidW = laneMarking('Solid','Width',0.3);
dashW = laneMarking('Dashed','Space',5);
doubleY = laneMarking('DoubleSolid','Color','yellow');
lspec = lanespec([2 2],'Width',[5 5 5 5], ...
    'Marking',[solidW dashW doubleY dashW solidW]);

Add the road to the driving scenario. Display the road.

road(scenario,roadCenters,'Lanes',lspec);
plot(scenario)

Simulate Car Traveling on S-Curve

Simulate a driving scenario with one car traveling on an S-curve. Create and plot the lane boundaries.

Create the driving scenario with one road having an S-curve.

scenario = drivingScenario('StopTime',3);
roadcenters = [-35 20 0; -20 -20 0; 0 0 0; 20 20 0; 35 -20 0];

Create the lanes and add them to the road.

lm = [laneMarking('Solid','Color','w'); ...
    laneMarking('Dashed','Color','y'); ...
    laneMarking('Dashed','Color','y'); ...
    laneMarking('Solid','Color','w')];
ls = lanespec(3,'Marking',lm);
road(scenario,roadcenters,'Lanes',ls);

Add an ego vehicle and specify its trajectory from its waypoints. By default, the car travels at a speed of 30 meters per second.

car = vehicle(scenario, ...
    'ClassID',1, ...
    'Position',[-35 20 0]);
waypoints = [-35 20 0; -20 -20 0; 0 0 0; 20 20 0; 35 -20 0];
smoothTrajectory(car,waypoints);

Plot the scenario and corresponding chase plot.

plot(scenario)

chasePlot(car)

Run the simulation loop.

1. Initialize a bird's-eye plot and create an outline plotter, left-lane and right-lane boundary plotters, and a road boundary plotter.

2. Obtain the road boundaries and rectangular outlines.

3. Obtain the lane boundaries to the left and right of the vehicle.

4. Advance the simulation and update the plotters.

bep = birdsEyePlot('XLim',[-40 40],'YLim',[-30 30]);
olPlotter = outlinePlotter(bep);
lblPlotter = laneBoundaryPlotter(bep,'Color','r','LineStyle','-');
lbrPlotter = laneBoundaryPlotter(bep,'Color','g','LineStyle','-');
rbsEdgePlotter = laneBoundaryPlotter(bep);
legend('off');
while advance(scenario)
    rbs = roadBoundaries(car);
    [position,yaw,length,width,originOffset,color] = targetOutlines(car);
    lb = laneBoundaries(car,'XDistance',0:5:30,'LocationType','Center', ...
        'AllBoundaries',false);
    plotLaneBoundary(rbsEdgePlotter,rbs)
    plotLaneBoundary(lblPlotter,{lb(1).Coordinates})
    plotLaneBoundary(lbrPlotter,{lb(2).Coordinates})
    plotOutline(olPlotter,position,yaw,length,width, ...
        'OriginOffset',originOffset,'Color',color)
end

Limitations

• Lane markings in intersections are not supported.

• The number of lanes for a road is fixed. You cannot change lane specifications for a road during a simulation.

More About

Draw Direction of Road and Numbering of Lanes

To create a road by using the road function, specify the road centers as a matrix input. The function creates a directed line that traverses the road centers, starting from the coordinates in the first row of the matrix and ending at the coordinates in the last row of the matrix. The coordinates in the first two rows of the matrix specify the draw direction of the road. These coordinates correspond to the first two consecutive road centers. The draw direction is the direction in which the roads render in the scenario plot.

To create a road by using the Driving Scenario Designer app, you can either specify the Road Centers parameter or interactively draw on the Scenario Canvas. For a detailed example, see Create a Driving Scenario. In this case, the draw direction is the direction in which roads render in the Scenario Canvas.

• For a road with a top-to-bottom draw direction, the difference between the x-coordinates of the first two consecutive road centers is positive.

• For a road with a bottom-to-top draw direction, the difference between the x-coordinates of the first two consecutive road centers is negative.

• For a road with a left-to-right draw direction, the difference between the y-coordinates of the first two consecutive road centers is positive.

• For a road with a right-to-left draw direction, the difference between the y-coordinates of the first two consecutive road centers is negative.

Numbering Lanes

Lanes must be numbered from left to right, with the left edge of the road defined relative to the draw direction of the road. For a one-way road, by default, the left edge of the road is a solid yellow marking which indicates the end of the road in transverse direction (direction perpendicular to draw direction). For a two-way road, by default, both edges are marked with solid white lines.

For example, these diagrams show how the lanes are numbered in a one-way and two-way road with a draw direction from top-to-bottom.

Numbering Lanes in a One-Way Road

Numbering Lanes in a Two-Way Road

Specify the number of lanes as a positive integer for a one-way road. If you set the integer value as 3, then the road has three lanes that travel in the same direction. The lanes are numbered starting from the left edge of the road. 1, 2, 3 denote the first, second, and third lanes of the road, respectively.

Specify the number of lanes as a two-element vector of positive integer for a two-way road. If you set the vector as [1 2], then the road has three lanes: two lanes traveling in one direction and one lane traveling in the opposite direction. Because of the draw direction, the road has one left lane and two right lanes. The lanes are numbered starting from the left edge of the road. 1L denote the only left lane of the road. 1R and 2R denote the first and second right lanes of the road, respectively.

The lane specifications apply by the order in which the lanes are numbered.

Lane Specifications

The diagram shows the components and geometric properties of roads, lanes, and lane markings.

The lane specification object, lanespec, defines the road lanes.

• The NumLanes property specifies the number of lanes. You must specify the number of lanes when you create this object.

• The Width property specifies the width of each lane.

• The Marking property contains the specifications of each lane marking in the road. Marking is an array of lane marking objects, with one object per lane. To create these objects, use the laneMarking function. Lane marking specifications include:

  • Type — Type of lane marking (solid, dashed, and so on)

  • Width — Lane marking width

  • Color — Lane marking color

  • Strength — Saturation value for lane marking color

  • Length — For dashed lanes, the length of each dashed line

  • Space — For dashed lanes, the spacing between dashes

  • SegmentRange — For composite lane marking, the normalized length of each marker segment

• The Type property contains the lane type specifications of each lane in the road. Type can be a homogeneous lane type object or a heterogeneous lane type array.

  • Homogeneous lane type object contains the lane type specifications of all the lanes in the road.

  • Heterogeneous lane type array contains an array of lane type objects, with one object per lane.

  To create these objects, use the laneType function. Lane type specifications include:

  • Type — Type of lane (driving, border, and so on)

  • Color — Lane color

  • Strength — Strength of the lane color

Version History

Introduced in R2018a