Platform

Platform object belonging to tracking scenario

Description

Platform defines a platform object belonging to a tracking scenario. Platforms represent the moving objects in a scenario and are modeled as points or cuboids with aspect-dependent properties.

Creation

You can create Platform objects using the platform method of trackingScenario.

Properties

PlatformID — Scenario-defined platform identifier

1 (default) | 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.

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

3-element vector of scalar

This property is read-only.

Current position of the platform, specified as a 3-element vector of scalars.

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

• When the IsEarthCentered property of the scenario is set to true, the position is expressed as a three element geodetic state: latitude in degrees, longitude in degrees, and altitude in meters.

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

Data Types: double

Orientation — Current orientation of platform

3-element vector of scalar

This property is read-only.

Current orientation of the platform, specified as a 3-element vector of scalars in degrees. The three scalars are the [yaw, pitch, roll] rotation angles from the local reference frame to the platform's body frame. The orientation is determined by the platform trajectory defined in the Trajectory property.

Data Types: double

Dimensions — Platform dimensions and origin offset

struct

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 following 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])

Data Types: struct

Trajectory — Platform motion

kinematicTrajectory object | waypointTrajectory object | geoTrajectory object

Platform motion, specified as either 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.

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

• When the IsEarthCentered property of the scenario is set to true, you can only use the geoTrajectory object. By default, a stationary geoTrajectory object is used.

Signatures — Platform signatures

{rcsSignature irSignature tsSignature} (default) | cell array of signature objects

Platform signatures, specified as a cell array of irSignature, rcsSignature, and tsSignature objects or an empty cell array. The cell array contains at most only one instance for each type of signature objects listed. 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

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

Emitters — Emitters mounted on platform

cell array of emitter objects

Emitters mounted on platform, specified as a cell array of emitter objects, such as radarEmitter or sonarEmitter.

Sensors — Sensors mounted on platform

cell array of sensor objects

Sensors mounted on platform, specified as a cell array of sensor objects such as irSensor, fusionRadarSensor, monostaticLidarSensor, or sonarSensor.

Mesh — Mesh of platform

extendedObjectMesh object (default)

Mesh of platform, specified as an extendedObjectMesh object. The object represents the mesh as vertices and faces. The monostaticLidarSensor object uses the platform mesh information to generate cloud data.

Object Functions

detect	Detect signals using platform-mounted sensors
lidarDetect	Report point cloud detections from all lidar sensor on platform
emit	Radiate signals from emitters mounted on platform
pose	Pose of platform
targetPoses	Target positions and orientations as seen from platform
targetMeshes	Target meshes as seen from platform

Examples

Platform Follows Circular Trajectory

Create a tracking scenario and a platform following a circular path.

scene = trackingScenario('UpdateRate',1/50);

% Create a platform
plat = platform(scene);

% Follow a circular trajectory 1 km in radius completing in 400 hundred seconds.
plat.Trajectory = waypointTrajectory('Waypoints', [0 1000 0; 1000 0 0; 0 -1000 0; -1000 0 0; 0 1000 0], ...
    'TimeOfArrival', [0; 100; 200; 300; 400]);

% Perform the simulation
while scene.advance
    p = pose(plat);
    fprintf('Time = %f ', scene.SimulationTime);
    fprintf('Position = [');
    fprintf('%f ', p.Position);
    fprintf('] Velocity = [');
    fprintf('%f ', p.Velocity);
    fprintf(']\n');
end

Time = 0.000000 

Position = [

0.000000 1000.000000 0.000000 

] Velocity = [

15.707701 -0.000493 0.000000 

]

Time = 50.000000 

Position = [

707.095476 707.100019 0.000000 

] Velocity = [

11.107152 -11.107075 0.000000 

]

Time = 100.000000 

Position = [

1000.000000 0.000000 0.000000 

] Velocity = [

0.000476 -15.707961 0.000000 

]

Time = 150.000000 

Position = [

707.115558 -707.115461 0.000000 

] Velocity = [

-11.107346 -11.107341 0.000000 

]

Time = 200.000000 

Position = [

0.000000 -1000.000000 0.000000 

] Velocity = [

-15.707963 0.000460 0.000000 

]

Time = 250.000000 

Position = [

-707.098004 -707.098102 0.000000 

] Velocity = [

-11.107069 11.107074 0.000000 

]

Time = 300.000000 

Position = [

-1000.000000 0.000000 0.000000 

] Velocity = [

-0.000476 15.707966 0.000000 

]

Time = 350.000000 

Position = [

-707.118086 707.113543 0.000000 

] Velocity = [

11.107262 11.107340 0.000000 

]

Time = 400.000000 

Position = [

-0.000000 1000.000000 0.000000 

] Velocity = [

15.708226 -0.000493 0.000000 

]

Cuboid Platforms Follow Circular Trajectories

Create a tracking scenario with two cuboid platforms following circular trajectories.

sc = trackingScenario;

% Create the platform for a truck with dimension 5 x 2.5 x 3.5 (m). 
p1 = platform(sc);
p1.Dimensions = struct('Length',5,'Width',2.5,'Height',3.5,'OriginOffset',[0 0 0]);

% Specify the truck's trajectory as a circle with radius 20 meters.
p1.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 dimension .3 x .3 x .1 (m).
p2 = platform(sc);
p2.Dimensions = struct('Length',.3,'Width',.3,'Height',.1,'OriginOffset',[0 0 0]);

% The quadcopter follows the truck at 10 meteres above with small angular delay.
% Note that the negative z coordinates correspond to positive elevation.
p2.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 animate.
view(-28,37);
set(gca,'Zdir','reverse');

while advance(sc)
    poses = platformPoses(sc);
    plotPlatform(pp1, poses(1).Position, p1.Dimensions, poses(1).Orientation);
    plotPlatform(pp2, poses(2).Position, p2.Dimensions, poses(2).Orientation);
end

Version History

Introduced in R2018b