Radius at Geocentric Latitude

Estimate radius of ellipsoid planet at geocentric latitude

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Libraries:
Aerospace Blockset / Flight Parameters

Description

The Radius at Geocentric Latitude block estimates the radius $$(r_s)$$ of an ellipsoid planet at a particular geocentric latitude $$({\lambda }_s)$$.

The following equation estimates the ellipsoid radius $$(r_s)$$ using flattening $$(\overline{f})$$, geocentric latitude $$({\overline{\lambda }}_s)$$, and equatorial radius $$(\overline{R})$$:

$$r_s=\sqrt{\frac{R^2}{1+\left[1/{(1-f)}^2-1\right]{\sin }^2{\lambda }_s}}.$$

Ports

Input

λ_s — Geocentric latitude

scalar | vector

Geocentric latitude, specified as a scalar or vector, in degrees.

Data Types: double

Output

r_s — Radius

scalar | vector

Radius of planet at geocentric latitude, returned as a scalar or vector, in the same units as flattening.

Data Types: double

Parameters

Units — Output units

Metric (MKS) (default) | English

Output units, specified as:

Units	Equatorial Radius	Radius at Geocentric Latitude
Metric (MKS)	Meters	Meters
English	Feet	Feet

Dependencies

To enable this parameter, set Planet model to Earth (WGS84).

Programmatic Use

Block Parameter: units

Type: character vector

Values: 'Metric (MKS)' | 'English'

Default: 'Metric (MKS)'

Planet model — Planet model

Earth (WGS84) (default) | Custom

Planet model to use, Custom or Earth (WGS84).

Programmatic Use

Block Parameter: ptype

Type: character vector

Values: 'Earth (WGS84)' | 'Custom'

Default: 'Earth (WGS84)'

Flattening — Flattening of planet

1/298.257223563 (default) | scalar

Flattening of the planet, specified as a double scalar.

Dependencies

To enable this parameter, set Planet model to Custom.

Programmatic Use

Block Parameter: F

Type: character vector

Values: double scalar

Default: 1/298.257223563

Equatorial radius of planet — Radius of planet at equator

6378137 (default) | scalar

Radius of the planet at its equator, in the same units as the desired units for ECEF position.

Dependencies

To enable this parameter, set Planet model to Custom.

Programmatic Use

Block Parameter: R

Type: character vector

Values: double scalar

Default: 6378137

References

[1] Stevens, Brian L., Frank L. Lewis. Aircraft Control and Simulation, New York, John Wiley & Sons, 1992.

[2] Zipfel, Peter H., Modeling and Simulation of Aerospace Vehicle Dynamics. Second Edition. Reston, VA: AIAA Education Series, 2000.

Extended Capabilities

C/C++ Code Generation
Generate C and C++ code using Simulink® Coder™.

Version History

Introduced before R2006a