platform

Platform object belonging to radar scenario

Description

The platform function creates a Platform object belonging to a radarScenario. You can mount senors on a platform that detect or emit signals in the radar scenario. Specify the platform signature as a radar cross section, target strength, or infrared intensity. You can model platforms as points or cuboids by specifying the Dimensions property and use the PoseEstimator property to determine the current platform pose with respect to local scenario coordinates. You can create trajectories for any platform using the kinematicTrajectory, waypointTrajectory, or geoTrajectory System object™.

Use the detect, emit, and receive functions to collect detection, emissions, and receive I/Q signals for all senors mounted on the platform, respectively. You can use pose to update the pose for a platform. targetPoses returns the poses of all targets in a scenario with respect to the observing platform.

Creation

Syntax

plat = platform(scenario)

plat = platform(scenario,PropertyName=Value)

Description

plat = platform(scenario) creates a new Platform object, plat, and adds the platform to the radar scenario, scenario.

plat = platform(scenario,PropertyName=Value) creates a new Platform object, plat, with each specified PropertyName set to the corresponding Value. You can specify additional pairs of arguments in any order as PropertyName1=Value1,...,PropertyNameN=ValueN.

Properties

PlatformID — Scenario-defined platform identifier

Read-only: positive integer

This property is read-only.

Scenario-defined platform identifier, specified as a positive integer. The scenario automatically assigns PlatformID values to each platform, starting with 1 for the first platform and incrementing by 1 for each new platform.

Data Types: double

ClassID — Platform classification identifier

0 (default) | nonnegative integer

Platform classification identifier, specified as a nonnegative integer. You can define your own platform classification scheme and assign ClassID values to platforms according to the scheme. The value of 0 is reserved for an object of unknown or unassigned class.

Example: 5

Data Types: double | single

Position — Current position of platform

Read-only: three-element numeric vector

This property is read-only.

Current position of the platform, specified as a three-element numeric vector.

• When the IsEarthCentered property of the scenario is set to false, the position is expressed as Cartesian coordinates [x, y, z] in meters.

• When the IsEarthCentered property of the scenario is set to true, the position is expressed as geodetic coordinates [latitude, longitude, altitude], where latitude and longitude are in degrees and altitude is in meters.

The position is determined by the platform trajectory defined in the Trajectory property.

Data Types: double

Orientation — Current orientation of platform

Read-only: three-element numeric vector

This property is read-only.

Current orientation of the platform, specified as a three-element numeric vector in degrees. The orientation is expressed as [yaw, pitch, roll] rotation angles from the local reference frame to the body frame of the platform. The orientation is determined by the platform trajectory defined in the Trajectory property.

Data Types: double

Dimensions — Platform dimensions and origin offset

struct('Length',0,'Width',0,'Height',0,'OriginOffset',[0 0 0]) | structure

Platform dimensions and origin offset, specified as a structure. The structure contains the Length, Width, Height, and OriginOffset of a cuboid that approximates the dimensions of the platform. The OriginOffset is the position vector from the center of the cuboid to the origin of the platform coordinate frame. The OriginOffset is expressed in the platform coordinate system. For example, if the platform origin is at the center of the cuboid rear face as shown in the figure, then set OriginOffset as [-L/2, 0, 0]. The default value for Dimensions is a structure with all fields set to zero, which corresponds to a point model.

Fields of Dimensions

Fields	Description	Default
Length	Dimension of a cuboid along the x direction	0
Width	Dimension of a cuboid along the y direction	0
Height	Dimension of a cuboid along the z direction	0
OriginOffset	Position of the platform coordinate frame origin with respect to the cuboid center	[0 0 0 ]

Example: struct('Length',5,'Width',2.5,'Height',3.5,'OriginOffset',[-2.5 0 0])

• For the radarTransceiver platform Length, Width, and Height can be set to any non-negative values when used in a radarScenario.

• For the radarDataGenerator, platform Length, Width, and Height are ignored if set to non-zero values in a radarScenario. All platforms are considered points.

Data Types: struct

Trajectory — Platform motion

kinematicTrajectory object | waypointTrajectory object | geoTrajectory object

Platform motion, specified as a kinematicTrajectory object, a waypointTrajectory object, or a geoTrajectory object. The trajectory object defines the time evolution of the position and velocity of the platform frame origin, as well as the orientation of the platform frame relative to the scenario frame. The SampleRate property of the trajectory object will automatically be set to the UpdateRate property of the radarScenario and the SamplesPerFrame of the trajectory object will be set to 1.

• When the IsEarthCentered property of the scenario is set to false, use the kinematicTrajectory or the waypointTrajectory object. By default, the platform uses a stationary kinematicTrajectory object.

• When the IsEarthCentered property of the scenario is set to true, use the geoTrajectory object. By default, the platform uses a stationary geoTrajectory object.

Signatures — Platform signatures

cell array of signature objects | {}

Platform signatures, specified as a cell array of signature objects or an empty cell array ({}). The default value is a cell array containing an rcsSignature object with default property values. If you have Sensor Fusion and Tracking Toolbox™, then the cell array can also include irSignature (Sensor Fusion and Tracking Toolbox) and tsSignature (Sensor Fusion and Tracking Toolbox) objects. The cell array contains at most one instance of each type of signature object. A signature represents the reflection or emission pattern of a platform, such as its radar cross-section, target strength, or IR intensity.

PoseEstimator — Platform pose estimator

insSensor object (default) | pose estimator object

Platform pose estimator, specified as a pose-estimator object such as an insSensor object. The pose estimator determines the platform pose with respect to the local NED scenario coordinates. The interface of any pose estimator must match the interface of the insSensor object. By default, the pose-estimator accuracy properties are zero.

Emitters — Emitters mounted on platform

cell array of emitter objects

Emitters mounted on the platform, specified as a cell array of emitter objects such as radarEmitter objects. If you have Sensor Fusion and Tracking Toolbox, then the cell array can also include sonarEmitter (Sensor Fusion and Tracking Toolbox) objects.

Sensors — Sensors mounted on platform

cell array of sensor objects

Sensors mounted on the platform, specified as a cell array of sensor objects such as radarDataGenerator or radarTransceiver objects.

Object Functions

detect	Collect detections from all sensors mounted on platform
emit	Collect emissions from all emitters mounted on platform
pose	Update pose for platform
receive	Receive I/Q signal from radars mounted on platform
targetPoses	Target positions and orientations as seen from platform

Examples

Create Radar Scenario with Two Platforms

Create a radar scenario with two platforms that follow different trajectories.

sc = radarScenario('UpdateRate',100,'StopTime',1.2);

Create two platforms.

platfm1 = platform(sc);
platfm2 = platform(sc);

Platform 1 follows a circular path of radius 10 m for one second. This is accomplished by placing waypoints in a circular shape, ensuring that the first and last waypoint are the same.

wpts1 = [0 10 0; 10 0 0; 0 -10 0; -10 0 0; 0 10 0];
time1 = [0; 0.25; .5; .75; 1.0];
platfm1.Trajectory = waypointTrajectory(wpts1,time1);

Platform 2 follows a straight path for one second.

wpts2 = [-8 -8 0; 10 10 0];
time2 = [0; 1.0];
platfm2.Trajectory = waypointTrajectory(wpts2,time2);

Verify the number of platforms in the scenario.

disp(sc.Platforms)

    {1×1 radar.scenario.Platform}    {1×1 radar.scenario.Platform}

Run the simulation and plot the current position of each platform using an animated line.

figure
grid
axis equal
axis([-12 12 -12 12])
line1 = animatedline('DisplayName','Trajectory 1','Color','b','Marker','.');
line2 = animatedline('DisplayName','Trajectory 2','Color','r','Marker','.');
title('Trajectories')
p1 = pose(platfm1);
p2 = pose(platfm2);
addpoints(line1,p1.Position(1),p1.Position(2));
addpoints(line2,p2.Position(2),p2.Position(2));

while advance(sc)
    p1 = pose(platfm1);
    p2 = pose(platfm2);
    addpoints(line1,p1.Position(1),p1.Position(2));
    addpoints(line2,p2.Position(2),p2.Position(2));
    pause(0.1)
end

Plot the waypoints for both platforms.

hold on
plot(wpts1(:,1),wpts1(:,2),' ob')
text(wpts1(:,1),wpts1(:,2),"t = " + string(time1),'HorizontalAlignment','left','VerticalAlignment','bottom')
plot(wpts2(:,1),wpts2(:,2),' or')
text(wpts2(:,1),wpts2(:,2),"t = " + string(time2),'HorizontalAlignment','left','VerticalAlignment','bottom')
hold off

Create Platform with Circular Trajectory

Create a radar scenario.

rs = radarScenario;

Create a platform with default property values and add it to the scenario.

plat = platform(rs);

Specify the trajectory of the platform as a circular path of radius 10 m for one second. This is accomplished by placing waypoints in a circular shape, ensuring that the first and last waypoint are the same.

wpts = [0 10 0; 10 0 0; 0 -10 0; -10 0 0; 0 10 0];
times = [0; 0.25; .5; .75; 1.0];
plat.Trajectory = waypointTrajectory(wpts,times);

Display the properties of the platform object.

plat

plat = 
  Platform with properties:

       PlatformID: 1
          ClassID: 0
         Position: [0 10 0]
      Orientation: [-1.7180e-05 0 0]
       Dimensions: [1×1 struct]
       Trajectory: [1×1 waypointTrajectory]
    PoseEstimator: [1×1 insSensor]
         Emitters: {}
          Sensors: {}
       Signatures: {[1×1 rcsSignature]}

Perform the simulation, advancing one time step at a time. Display the simulation time and the position and velocity of the platform at each time step.

while advance(rs)  
    p = pose(plat);
    disp(strcat("Time = ",num2str(rs.SimulationTime)))
    disp(strcat("  Position = [",num2str(p.Position),"]"))
    disp(strcat("  Velocity = [",num2str(p.Velocity),"]"))
end

Time = 0

  Position = [0  10   0]

  Velocity = [62.8318 -1.88403e-05            0]

Time = 0.1

  Position = [5.8779      8.0902           0]

  Velocity = [50.832     -36.9316            0]

Time = 0.2

  Position = [9.5106      3.0902           0]

  Velocity = [19.4161     -59.7566            0]

Time = 0.3

  Position = [9.5106     -3.0902           0]

  Velocity = [-19.4161     -59.7567            0]

Time = 0.4

  Position = [5.8779     -8.0902           0]

  Velocity = [-50.832     -36.9316            0]

Time = 0.5

  Position = [0 -10   0]

  Velocity = [-62.8319  1.88181e-05            0]

Time = 0.6

  Position = [-5.8779     -8.0902           0]

  Velocity = [-50.832      36.9316            0]

Time = 0.7

  Position = [-9.5106     -3.0902           0]

  Velocity = [-19.4161      59.7566            0]

Time = 0.8

  Position = [-9.5106      3.0902           0]

  Velocity = [19.4161      59.7566            0]

Time = 0.9

  Position = [-5.8779      8.0902           0]

  Velocity = [50.832      36.9316            0]

Time = 1

  Position = [-7.10543e-15           10            0]

  Velocity = [62.8319 -1.88404e-05            0]

Create Cuboid Platforms with Circular Trajectory

Create a radar scenario.

rs = radarScenario;

Create a cuboid platform for a truck with dimensions 5 m by 2.5 m by 3.5 m.

dim1 = struct('Length',5,'Width',2.5,'Height',3.5,'OriginOffset',[0 0 0]);
truck = platform(rs,'Dimension',dim1);

Specify the trajectory of the truck as a circle with radius 20 m.

truck.Trajectory = waypointTrajectory('Waypoints', ...
    [20*cos(2*pi*(0:10)'/10) 20*sin(2*pi*(0:10)'/10) -1.75*ones(11,1)], ...
    'TimeOfArrival',linspace(0,50,11)');

Create the platform for a small quadcopter with dimensions 0.3 m by 0.3 m by 0.1 m.

dim2 = struct('Length',.3,'Width',.3,'Height',.1,'OriginOffset',[0 0 0]);
quad = platform(rs,'Dimension',dim2);

Specify the trajectory of the quadcopter as a circle 10 m above the truck with a small angular delay. Note that the negative z coordinates correspond to positive elevation.

quad.Trajectory = waypointTrajectory('Waypoints', ...
    [20*cos(2*pi*((0:10)'-.6)/10) 20*sin(2*pi*((0:10)'-.6)/10) -11.80*ones(11,1)], ...
    'TimeOfArrival',linspace(0,50,11)');

Visualize the results using theaterPlot.

tp = theaterPlot('XLim',[-30 30],'YLim',[-30 30],'Zlim',[-12 5]);
pp1 = platformPlotter(tp,'DisplayName','truck','Marker','s');
pp2 = platformPlotter(tp,'DisplayName','quadcopter','Marker','o');

Specify a view direction and run the simulation.

view(-28,37);
set(gca,'Zdir','reverse');

while advance(rs)
    poses = platformPoses(rs);
    plotPlatform(pp1,poses(1).Position,truck.Dimensions,poses(1).Orientation);
    plotPlatform(pp2,poses(2).Position,quad.Dimensions,poses(2).Orientation);
end

Version History

Introduced in R2021a