CubeSat Vehicle

Model CubeSat vehicle

  • Library:
  • Aerospace Blockset / Aerospace Blockset CubeSat Simulation Library

Description

The CubeSat Vehicle block models CubeSat vehicles to provide a high level mission planning/rapid prototyping option to quickly model and propagate satellite orbits. To accommodate constellation planning workflows, you can also use these blocks multiple times in a model. Specify this information for the vehicle:

  • Initial orbital state

  • Attitude control (pointing) mode

The Aerospace Blockset™ CubeSat Simulation Library contains three versions of the CubeSat Vehicle block preconfigured for common attitude control modes:

  • Earth (Nadir) Pointing — Primary alignment vector points towards the center of the Earth

  • Sun Tracking — Primary alignment vector points toward the Sun

  • Custom Pointing — Custom alignment and constraint vectors

To access the Aerospace Blockset CubeSat Simulation Library, type asbCuteSatBlockLib in the MATLAB® Command Window.

Limitations

The CubeSat Vehicle block is available only through the Add-On Explorer.

Ports

Input

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Vehicle gravity accelerations (including gravity) used for orbit propagation, specified as a vector of size 3, in m/s2.

Data Types: single | double

Primary alignment vector, in the Body frame, to align with primary constraint vector.

Data Types: double

Primary constraint vector specifying the direction in which to align the primary alignment vector.

Dependencies

This port is not available when Pointing mode is set to Earth (Nadir) Pointing or Sun Tracking, which have implied primary constraint vectors.

Data Types: double

Primary alignment vector, in the Body frame, to align with primary constraint vector.

Data Types: double

Primary constraint vector specifying the direction in which to align the primary alignment vector.

Dependencies

  • The direction depends on the Constraint coordinate system.

  • This port is not available when Pointing mode is set to Earth (Nadir) Pointing or Sun Tracking, which have implied primary constraint vectors.

Data Types: double

Secondary alignment vector, in the Body frame, to align with secondary constraint vector.

Data Types: double

Secondary constraint vector specifying the direction in which to align the secondary alignment vector.

Dependencies

The direction depends on the Constraint coordinate system.

Data Types: double

Output

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Earth-centered Earth-fixed CubeSat position components, specified as a 3-by-1 array.

Data Types: double

Earth-centered Earth-fixed velocity components, specified as a 3-by-1 array.

Data Types: double

Quaternion rotation from Earth-centered inertial frame to Body frame.

Data Types: double

Quaternion rotation from Earth-centered Earth-fixed frame to Body frame.

Data Types: double

Parameters

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Initial start date of simulation. The block defines initial conditions using this date.

Tip

To calculate the Julian date, use the juliandate function.

Programmatic Use

Block Parameter: sim_t0
Type: character vector
Values: Julian date
Default: '2458488'

CubeSat Orbit

Initial vehicle position and velocity input method.

Dependencies

Selecting the Keplerian Orbital Elements input method enables these parameters:

  • Epoch of ECI frame [Julian date]

  • Semi-major axis [m]

  • Eccentricity

  • Inclination [deg]

  • Right ascension of the ascending node [deg]

  • Argument of periapsis [deg]

  • True anomaly [deg]

  • True longitude [deg] (circular equatorial)

  • Argument of latitude [deg] (circular inclined)

  • Longitude of periapsis [deg] (elliptical equatorial)

Selecting the ECI Position and Velocity input method enables these parameters:

  • Epoch of ECI frame [Julian date]

  • ECI position vector [m]

  • ECI velocity vector [m/s]

Selecting the ECEF Position and Velocity input method enables these parameters:

  • ECEF position vector [m]

  • ECEF velocity vector [m/s]

Selecting the Geodetic LatLonAlt and Velocity in NED input method enables these parameters:

  • Geodetic latitude, longitude, altitude [deg, deg, m]

  • NED velocity vector [m/s]

Programmatic Use

Block Parameter: method
Type: character vector
Values: 'Keplerian Orbital Elements' | 'ECI Postion and Velocit' | 'ECEF Postion and Velocity' | 'Geodetic LatLonAlt and Velocity in NED'
Default: 'Keplerian Orbital Elements'

Epoch of ECI frame, specified as a Julian date.

Tip

To calculate the Julian date for a particular date, use the juliandate function.

Programmatic Use

Block Parameter: epoch
Type: character vector
Values: Julian date format
Default: '2451545'

CubeSat semi-major axis (half of the longest orbit diameter), specified in m.

Programmatic Use

Block Parameter: a
Type: character vector
Values: scalar
Default: '6878137'

Deviation of the CubeSat orbit from a perfect circle.

Programmatic Use

Block Parameter: ecc
Type: character vector
Values: scalar
Default: '0'

Tilt angle of CubeSat orbital plane, specified between 0 and 180 deg.

Programmatic Use

Block Parameter: incl
Type: character vector
Values: scalar
Default: '0'

Angular distance in equatorial plane from x-axis to location of the ascending node (point at which the satellite crosses the equator from south to north), specified between 0 and 360 deg.

Programmatic Use

Block Parameter: omega
Type: character vector
Values: scalar
Default: '0'

Angle from the CubeSat body ascending node to the periapsis (closest point of orbit to Earth), specified between 0 and 360 deg.

Programmatic Use

Block Parameter: argp
Type: character vector
Values: scalar
Default: '0'

Angle between the periapsis (closest point of orbit to Earth) and the current position of CubeSat, specified between 0 and 360 deg.

Programmatic Use

Block Parameter: nu
Type: character vector
Values: scalar
Default: '0'

Angle between x-axis of periapsis and position of CubeSat vector, specified between 0 and 360 deg.

Programmatic Use

Block Parameter: truelon
Type: character vector
Values: scalar
Default: '0'

Angle between ascending node and satellite position vector, specified between 0 and 360 deg.

Programmatic Use

Block Parameter: arglat
Type: character vector
Values: scalar
Default: '0'

Angle between the x-axis of the periapsis and the eccentricity vector, specified between 0 and 360 deg.

Programmatic Use

Block Parameter: lonper
Type: character vector
Values: scalar
Default: '0'

Cartesian position vector of satellite in ECI coordinate frame at Start Date.

Programmatic Use

Block Parameter: r_eci
Type: character vector
Values: scalar
Default: '[0 0 0]'

Cartesian velocity vector of satellite in ECI coordinate frame at Start Date.

Programmatic Use

Block Parameter: v_eci
Type: character vector
Values: scalar
Default: '[0 0 0]'

Cartesian position vector of satellite in ECEF coordinate frame at Start Date.

Programmatic Use

Block Parameter: r_ecef
Type: character vector
Values: scalar
Default: '[0 0 0]'

Cartesian velocity vector of satellite in ECEF coordinate frame at Start Date.

Programmatic Use

Block Parameter: v_ecef
Type: character vector
Values: scalar
Default: '[0 0 0]'

Geodetic latitude and longitude, in deg, and altitude above WGS84 ellipsoid, in m.

Programmatic Use

Block Parameter: lla
Type: character vector
Values: scalar
Default: '[0 0 0]'

Body velocity with respect to Earth-centered Earth-fixed (ECEF), expressed in the north-east-down (NED) coordinate frame, specified as a vector, in m/s.

Programmatic Use

Block Parameter: v_ned
Type: character vector
Values: scalar
Default: '[0 0 0]'

CubeSat Attitude

Initial Euler rotation angles (roll, pitch, yaw) between Body and NED coordinate frames, specified in degrees.

Programmatic Use

Block Parameter: euler
Type: character vector
Values: scalar
Default: '[0 0 0]'

Initial angular rates with respect to NED frame, expressed in Body frame, specified as a vector.

Programmatic Use

Block Parameter: pqr
Type: character vector
Values: scalar
Default: '[0 0 0]'

CubeSat vehicle pointing mode, specified as Earth (Nadir) Pointing, Sun Tracking, or Custom Pointing. The CubeSat vehicle uses the pointing mode for precise attitude control. For no attitude control, select Standby (Off).

Programmatic Use

Block Parameter: pointingMode
Type: character vector
Values: 'Earth (Nadir) Pointing' | 'Sun Tracking' | 'Custom Pointing' | 'Standby (Off)'
Default: 'Earth (Nadir) Pointing'

Primary alignment vector, in Body frame, to align with primary constraint vector.

Dependencies

  • Selecting Dialog enables a text box in which you specify the primary alignment vector. The default value is [0 0 1].

  • Selecting Input port enables the 1st AlignmentBody input port, at which you specify the primary alignment vector.

Programmatic Use

Block Parameter: firstAlign
Type: character vector
Values: vector
Default: '[0 0 1]'

Programmatic Use

Block Parameter: firstAlignExt
Type: character vector
Values: 'Input port' | 'Dialog'
Default: 'Dialog'

Secondary alignment vector, in Body frame, to align with secondary constraint vector.

Dependencies

  • Selecting Dialog enables a text box in which you specify the secondary alignment vector. The default value is [0 1 0].

  • Selecting Input port enables the 2nd AlignmentBody input port, at which you specify the secondary alignment vector.

Programmatic Use

Block Parameter: secondAlign
Type: character vector
Values: vector
Default: '[0 1 0]'

Programmatic Use

Block Parameter: secondAlignExt
Type: character vector
Values: 'Input port' | 'Dialog'
Default: 'Dialog'

Constraint coordinate system, specified as ECI Axes, ECEF Axes, NED Axes, or Body-Fixed Axes.

Programmatic Use

Block Parameter: constraintCoord
Type: character vector
Values: 'ECI Axes' | 'ECEF Axes' | 'NED Axes' | 'Body-Fixed Axes'
Default: 'ECI Axes'

Primary constraint vector, in the Body frame, to align with the primary alignment vector.

Dependencies

  • This parameter is disabled when Pointing mode is Earth (Nadir) Pointing or Sun Tracking.

  • Selecting Dialog enables a text box in which you specify the primary constraint vector. The default value is [1 0 0].

  • Selecting Input port enables the 1st constraintBody input port, at which you specify the primary constraint vector.

Programmatic Use

Block Parameter: firstRef
Type: character vector
Values: vector
Default: '[1 0 0]'

Programmatic Use

Block Parameter: firstRefExt
Type: character vector
Values: 'Input port' | 'Dialog'
Default: 'Dialog'

Secondary constraint vector, in the Body frame, to align with the secondary alignment vector.

Dependencies

  • Selecting Dialog enables a text box in which you specify the secondary constraint vector. The default value is [0 0 1].

  • Selecting Input port enables the 2nd constraintBody input port, at which you specify the secondary constraint vector.

Programmatic Use

Block Parameter: secondRef
Type: character vector
Values: vector
Default: '[0 0 1]'

Programmatic Use

Block Parameter: secondRefExt
Type: character vector
Values: 'Input port' | 'Dialog'
Default: 'Dialog'

Earth Orientation Parameters

Difference between International Atomic Time (TAI) and Coordinated Universal Time (UTC), specified as a scalar, in sec.

Programmatic Use

Block Parameter: dAT
Type: character vector
Values: scalar
Default: '0'

Scalar value specifying the difference between UTC and UT1, specified as a scalar, in sec.

Programmatic Use

Block Parameter: dUT1
Type: character vector
Values: scalar
Default: '0'

Polar displacements due to the motion of Earth crust along the x- and y-axis, specified as a 1-by-2 array, in deg.

Programmatic Use

Block Parameter: pm
Type: character vector
Values: scalar
Default: '[0 0]'

Adjustments to the location of the Celestial Intermediate Pole (CIP) along the x- and y-axis, specified as a 1-by-2 array, in deg.

Programmatic Use

Block Parameter: dCIP
Type: character vector
Values: scalar
Default: '[0 0]'

Excess length of day (difference between astronomically determined duration of day and 86400 seconds), specified as a scalar, in International System of Units (SI) sec.

Programmatic Use

Block Parameter: lod
Type: character vector
Values: scalar
Default: '0'

Mission Analysis

Source of run time for mission analysis live script, specified as:

  • Dialog — Defined in Run time parameter.

  • Model Stop Time — Defined in model configuration parameter Stop Time.

Programmatic Use

Block Parameter: missionRTSource
Type: character vector
Values: 'Dialog' | 'Model StopTime'
Default: 'Dialog'

Run time for mission analysis live script, specified as a scalar.

Programmatic Use

Block Parameter: missionRT
Type: character vector
Values: scalar
Default: '6*60*60'

Ground station location, specified as a vector, in geodetic latitude and longitude in deg, deg.

Programmatic Use

Block Parameter: missionGS
Type: character vector
Values: vector
Default: '[42, -71]'

Select this check box to enable time of interest analysis in mission analysis.live script

Programmatic Use

Block Parameter: missionTOICheck
Type: character vector
Values: 'on' | 'off'
Default: 'on'

Time of interest mission analysis, specified as a Julian date. To use the simulation start date, enter an empty array ([]).

Tip

To calculate the Julian date, use the juliandate function.

Programmatic Use

Block Parameter: missionTOI
Type: character vector
Values: Julian date
Default: '[]'

Half angle of field of view for nadir on-pointed camera. To exclude from analysis, enter an empty array ([]).

Programmatic Use

Block Parameter: missionEta
Type: character vector
Values: '[]' | scalar
Default: '55'

File name for mission analysis live script report, generated as a live script. To create a default mission analysis report with the format CubeSatMissionReport_currentdate.mlx, leave the parameter blank. To create a live script of the mission analysis report, click the Create Live Script Report button.

Dependencies

To create the live script with the specified file name, click the Create Live Script Report button. If this parameter is blank, the block creates a live script with a default file name.

Programmatic Use

Block Parameter: missionName
Type: character vector
Values: blank entry | file name
Default: blank entry

To analyze mission and create report in live script format, click this button. To create a default mission analysis report with the format CubeSatMissionReport_currentdate.mlx, leave the parameter blank. To create a live script of the mission analysis report, click the Create Live Script Report button.

Dependencies

To create the live script with the file name specified in Live script file name, click the Create Live Script Report button. If Live script file name is blank, the block creates a live script with a default file name.

References

[1] Wertz, James R, David F. Everett, and Jeffery J. Puschell. Space Mission Engineering: The New Smad. Hawthorne, CA: Microcosm Press, 2011. Print.

Extended Capabilities

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Introduced in R2019a