trafficgen.marine_system_simulator

The Marine Systems Simulator (MSS) is a Matlab and Simulink library for marine systems.

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