Motion Platform

Motion platform

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Libraries:
Phased Array System Toolbox / Environment and Target

Description

The Motion Platform block models the motion of multiple platforms such as airplanes, ground vehicles, and/or receiving and transmitting sensors arrays, determining their positions and velocities. The platforms move along trajectories determined by initial positions and velocities, according to which motion model you choose — the velocity or acceleration model. The platform positions and velocities are updated at each simulation step. In addition, you can specify initial orientations for the platforms and obtain orientation updates.

Ports

Input

Ref — Reference time input

scalar

Reference time input, specified as a scalar. Units are in seconds.

Dependencies

To enable this port, set the Source of elapsed simulation time parameter to Derive from reference input port.

Data Types: double

Vel — Platform velocity input

real-valued 3-by-N matrix

Platform velocity, specified as a real-valued 3-by-N matrix where N is the number of platforms to model. Units are meters per second.

Dependencies

To enable this port, set the Model of object motion parameter to Velocity and the Source of velocity parameter to Input port.

Data Types: double

Acl — Platform acceleration input

real-valued 3-by-N matrix

Platform acceleration input, specified as a real-valued 3-by-N matrix where N is the number of platforms to model. Units are meters per second-squared.

Dependencies

To enable this port, set the Model of object motion parameter to Acceleration and the Source of acceleration parameter to Input port.

Data Types: double

Output

Pos — Platform position output

real-valued 3-by-N matrix

Current position of platform, returned as a real-valued 3-by-1 column vector in the form of [x;y;z] or a real-valued 3-by-N matrix where N is the number of platforms to model. Each column takes the form [x;y;z]. Units are meters.

Data Types: double

Vel — Platform velocity output

real-valued 3-by-N matrix

Current velocity of platform, specify as a real-valued 3-by-1 column vector in the form of [vx;vy;vz] or a real-valued 3-by-N matrix where N is the number of platforms to model. Each column taking the form [vx;vy;vz]. Velocity units are meters per second.

Data Types: double

LAxes — Platform orientation output

real-valued 3-by-3-by-N matrix

Current platform orientation axes, returned as real-valued 3-by-3-by-N matrix where N is the number of platforms to model. Each 3-by-3 submatrix is an orthonormal matrix. This output is enabled when you set the OrientationAxesOutputPort property to true. The current platform axes rotate around the normal vector to the path of the platform.

Dependencies

To enable this port, select the Enable orientation axes output check box.

Data Types: double

Parameters

Model of object motion — Object motion model

Velocity (default) | Acceleration | Custom

Specify the object motion model as Velocity, Acceleration, or Custom. When you set this parameter to Velocity, the platform follows a constant velocity trajectory during each simulation step. When you set this parameter to Acceleration, the platform follows a constant acceleration trajectory during each simulation step. When you set the parameter to Custom, the platform motion follows a sequence of waypoints specified by the Custom trajectory waypoints parameter. The object performs a piecewise cubic interpolation on the waypoints to derive the position and velocity at each time step.

Initial position (m) — Initial position of platform

[0;0;0] (default)

Specify the initial position of the platform in meters as a 3-by-N matrix where each column represents the initial position of a platform in the form [x;y;z]. The quantity N is the number of platforms.

Initial velocity (m/s) — Initial velocity of platform

[0;0;0] (default)

Specify the initial velocity of the platform in m/s as a 3-by-N matrix where each column represents the initial velocity of a platform in the form [vx;vy;vz]. The quantity N is the number of platforms.

Dependencies

This parameter appears only when you set the Source of velocity or the Source of acceleration parameters to Input port.

Source of velocity — Source of velocity data

Property (default) | Input port

This parameter appears only when you set the Model of object motion parameter to Velocity. Then, you must supply velocity data for the model. Specify the Source of velocity data as either coming from a Property or an Input port.

Source of velocity	Use these model parameters or ports
Property	Initial position (m) parameter Velocity (m/s) parameter
Input port	Initial position (m) parameter Initial velocity (m/s) parameter Vel input port

Dependencies

This parameter appears only when you set the Model of object motion parameter to Velocity.

Velocity (m/s) — Current velocity of platform

[0;0;0] (default)

Specify the current velocity of the platforms in m/s as a 3-by-N matrix where each column represents the current velocity of a platform in the form [vx;vy;vz].

Dependencies

This parameter appears only when you set the Model of object motion parameter to Velocity and set the Source of velocity parameter to Property.

Source of acceleration — Source of acceleration data

Property (default) | Input port

This parameter appears only when you set the Model of object motion parameter to Acceleration. Then, you must supply acceleration values for the model. Specify the Source of acceleration data as either coming from a Property or an Input port.

Source of acceleration	Use these model parameters or ports
Property	Initial Position (m) parameter Initial Velocity (m/s) parameter Acceleration (m/s^2) parameter
Input port	Initial Position (m) parameter Initial Velocity (m/s) parameter Acl input port

Dependencies

This parameter appears only when you set the Model of object motion parameter to Acceleration.

Acceleration (m/s^2) — Acceleration of platform

[0;0;0] (default)

Specify the current acceleration of the platforms in m/s^2 as a 3-by-N matrix where each column represents the current acceleration of a platform in the form [ax;ay;az].

Dependencies

This parameter appears when you set the Model of object motion parameter to Acceleration and set the Source of acceleration parameter to Property.

Custom trajectory waypoints — Custom trajectory waypoints

[ 0, 0, 0, 0, 0, 0, 0; 1, 0, 0, 0, 0, 0, 0 ] (default)

Custom trajectory waypoints, specified as a real-valued M-by-L matrix, or M-by-L-by-N array. M is the number of waypoints. L is either 4 or 7.

• When L is 4, the first column indicates the times at which the platform position is measured. Columns 2 - 4 are position measurements in x, y, and z coordinates. The velocity is derived from the position measurements.

• When L is 7, columns 5 - 7 in the matrix are velocity measurements in x, y, and z coordinates.

When you set the Custom trajectory waypoints parameter to a three-dimensional array, the number of pages, N, represent the number of platforms. Time units are in seconds, position units are in meters, and velocity units are in meters per second.

Dependencies

To enable this property, set the Model of object motion property to Custom.

Mechanical scanning mode — Mechanical scanning mode

None (default) | Circular | Sector

Mechanical scan mode for platform, specified as None, Circular, or Sector, where None is the default. When you set the Mechanical scanning mode parameter to Circular, the platform scan clockwise 360 degrees continuously in the azimuthal direction of the platform orientation axes. When you set the Mechanical scanning mode parameter to Sector, the platform scans clockwise in the azimuthal direction in the platform orientation axes within a range specified by the Azimuth scan angle span (deg) parameter. When the platform scan reaches the span limits, the scan reverses direction and scans back to the other scan limit. Scanning happens within the orientation axes of the platform.

Initial scan angle (deg) — Initial scan angle of platform

0 (default)

Initial scan angle of platform, specified as a 1-by-N vector where N is the number of platforms. The scanning occurs in the local coordinate system of the platform. The Initial orientation axes parameter specifies the original local coordinate system. At the start of the simulation, the orientation axes specified by the Initial orientation axes are rotated by the angle specified in the InitialScanAngleInitial scan angle (deg) parameter. The default value is zero. Units are in degrees.

Dependencies

This parameter applies when you set the Mechanical scanning mode parameter to Circular or Sector.

Azimuth scan angle span (deg) — Azimuth span

[-60,60] (default)

Specify the azimuth angle span as an N-by-2 matrix where N is the number of platforms. Each row of the matrix specifies the scan range of the corresponding platform in the form [ScanAngleLowerBound ScanAngleHigherBound]. The default value is [-60 60]. Units are in degrees.

Dependencies

To enable this parameter, set the Mechanical scanning mode parameter to Sector.

Azimuth scan rate (deg/s) — Azimuth scan rate

10 (default)

Specify the azimuth scan rate as a 1-by-N vector where N is the number of platforms. Each entry in the vector is the azimuth scan rate for the corresponding platform. The default value is 10 degrees/second. Units are in degrees/second.

Dependencies

To enable this parameter, set the Mechanical scanning mode parameter to Circular or Sector.

Initial orientation axes — Initial orientation axes of platform

eye(3) (default)

Specify the three axes that define the initial local (x,y,z) coordinate system at the platform as a 3-by-3-by-N matrix. Each column of the matrix represents an axis of the local coordinate system. The three axes must be orthonormal.

Enable orientation axes output — Output orientation axes

off (default) | on

Select this check box to obtain the instantaneous orientation axes of the platform via the output port LAxes. The port appears only when the check box is selected.

Source of elapsed simulation time — Source of elapsed simulation time

Auto (default) | Derive from reference input port

Specify the source for elapsed simulation time as Auto or Derive from reference input port. When you choose Auto, the block computes the elapsed time. When you choose Derive from reference input port, the block uses the time duration of a reference signal passed into the Ref input port.

Inherit sample rate — Inherit sample rate from upstream blocks

on (default) | off

Select this parameter to inherit the sample rate from upstream blocks. Otherwise, specify the sample rate using the Sample rate (Hz) parameter.

Data Types: Boolean

Sample rate (Hz) — Sampling rate of signal

1e6 (default) | positive real-valued scalar

Specify the signal sampling rate as a positive scalar. Units are in Hz.

Dependencies

To enable this parameter, clear the Inherit sample rate check box.

Data Types: double

Simulate using — Block simulation method

Interpreted Execution (default) | Code Generation

Block simulation, specified as Interpreted Execution or Code Generation. If you want your block to use the MATLAB^® interpreter, choose Interpreted Execution. If you want your block to run as compiled code, choose Code Generation. Compiled code requires time to compile but usually runs faster.

Interpreted execution is useful when you are developing and tuning a model. The block runs the underlying System object™ in MATLAB. You can change and execute your model quickly. When you are satisfied with your results, you can then run the block using Code Generation. Long simulations run faster with generated code than in interpreted execution. You can run repeated executions without recompiling, but if you change any block parameters, then the block automatically recompiles before execution.

This table shows how the Simulate using parameter affects the overall simulation behavior.

When the Simulink^® model is in Accelerator mode, the block mode specified using Simulate using overrides the simulation mode.

Acceleration Modes

Block Simulation	Simulation Behavior
	Normal	Accelerator	Rapid Accelerator
Interpreted Execution	The block executes using the MATLAB interpreter.	The block executes using the MATLAB interpreter.	Creates a standalone executable from the model.
Code Generation	The block is compiled.	All blocks in the model are compiled.

For more information, see Choosing a Simulation Mode (Simulink).

Programmatic Use

Block Parameter:SimulateUsing

Type:enum

Values:Interpreted Execution, Code Generation

Default:Interpreted Execution

Version History

Introduced in R2014b