trafficgen.marine_system_simulator

The Marine Systems Simulator (MSS) is a Matlab and Simulink library for marine systems publicly available at https://github.com/cybergalactic/MSS.

It includes models for ships, underwater vehicles, unmanned surface vehicles, and floating structures. The library also contains guidance, navigation, and control (GNC) blocks for real-time simulation. The algorithms are described in:

T. I. Fossen (2021). Handbook of Marine Craft Hydrodynamics and Motion Control. 2nd. Edition, Wiley. ISBN-13: 978-1119575054

Parts of the library have been re-implemented in Python and are found below.

Functions

flat2llh(x_n, y_n, lat_0, lon_0[, z_n, ...])

Compute lon lon (rad), lat lat (rad) and height h (m) for the NED coordinates (xn,yn,zn).

llh2flat(lat, lon, lat_0, lon_0[, height, ...])

Compute (north, east) for a flat Earth coordinate system from lon lon (rad) and lat lat (rad).

ssa(angle)

Return the "smallest signed angle" (SSA) or the smallest difference between two angles.
trafficgen.marine_system_simulator.flat2llh(x_n: float, y_n: float, lat_0: float, lon_0: float, z_n: float = 0.0, height_ref: float = 0.0) → tuple[float, float, float]

Compute lon lon (rad), lat lat (rad) and height h (m) for the NED coordinates (xn,yn,zn).

Method taken from the MSS (Marine System Simulator) toolbox which is a Matlab/Simulink library for marine systems.

The method computes lon lon (rad), lat lat (rad) and height h (m) for the NED coordinates (xn,yn,zn) using a flat Earth coordinate system defined by the WGS-84 ellipsoid. The flat Earth coordinate origin is located at (lon_0, lat_0) with reference height h_ref in meters above the surface of the ellipsoid. Both height and h_ref are positive upwards, while zn is positive downwards (NED). Author: Thor I. Fossen Date: 20 July 2018 Revisions: 2023-02-04 updates the formulas for lat and lon

Parameters:

  • x_n (float) – Ship position, north [m]

  • y_n (float) – Ship position, east [m]

  • lat_0 (float) – Flat earth coordinate located at (lon_0, lat_0)

  • lon_0 (float) – Flat earth coordinate located at (lon_0, lat_0)

  • z_n (float) – Ship position, down [m], default is 0.0

  • h_ref (float) – Flat earth coordinate with reference h_ref in meters above the surface of the ellipsoid, default is 0.0

Returns:

  • lat (float) – Ship position in lat [rad]

  • lon (float) – Ship position in lon [rad]

  • h (float) – Ship height in meters above the surface of the ellipsoid [m]

trafficgen.marine_system_simulator.llh2flat(lat: float, lon: float, lat_0: float, lon_0: float, height: float = 0.0, height_ref: float = 0.0) → tuple[float, float, float]

Compute (north, east) for a flat Earth coordinate system from lon lon (rad) and lat lat (rad).

Method taken from the MSS (Marine System Simulator) toolbox which is a Matlab/Simulink library for marine systems.

The method computes (north, east) for a flat Earth coordinate system from lon lon (rad) and lat lat (rad) of the WGS-84 elipsoid. The flat Earth coordinate origin is located at (lon_0, lat_0). Author: Thor I. Fossen Date: 20 July 2018 Revisions: 2023-02-04 updates the formulas for lat and lon

Parameters:

  • lat (float) – Ship position in lat [rad]

  • lon (float) – Ship position in lon [rad]

  • lat_0 (float) – Flat earth coordinate located at (lon_0, lat_0)

  • lon_0 (float) – Flat earth coordinate located at (lon_0, lat_0)

  • h (float) – Ship height in meters above the surface of the ellipsoid, default is 0.0

  • h_ref (float) – Flat earth coordinate with reference h_ref in meters above the surface of the ellipsoid

Returns:

  • x_n (float) – Ship position, north [m]

  • y_n (float) – Ship position, east [m]

  • z_n (float) – Ship position, down [m]

trafficgen.marine_system_simulator.ssa(angle: float) → float

Return the “smallest signed angle” (SSA) or the smallest difference between two angles.

Method taken from the MSS (Marine System Simulator) toolbox which is a Matlab/Simulink library for marine systems.

Examples

angle = ssa(angle) maps an angle in rad to the interval [-pi pi)

Author: Thor I. Fossen Date: 2018-09-21

Parameters:

angle (float) – Angle given in radius

Returns:

smallest_angle – “smallest signed angle” or the smallest difference between two angles

Return type:

float