qbeslab / MagneticModelApp

MagneticModelApp

This repository holds code that performs simulations and generates figures published in

Gill, J. P., & Taylor, B. K. (2024). Navigation by magnetic signatures in a realistic model of Earth's magnetic field. Bioinspiration & Biomimetics, 19(3), 036006. https://doi.org/10.1088/1748-3190/ad3120

For the version of the code used at time of publication, see the Gill-and-Taylor-2024-Bioinspir-Biomim branch of the repository.

Requirements

Requires MATLAB R2021a or later.

Required add-ons (use MATLAB's Add-On Explorer to install):

• Aerospace Toolbox
• Mapping Toolbox
• getContourLineCoordinates (from MathWorks File Exchange)

Optional add-ons (use MATLAB's Add-On Explorer to install):

• MATLAB Basemap Data - colorterrain (install for offline use)
• Parallel Computing Toolbox (install for potential speed gains)

Example scripts:

• RunAxesmFigure
• RunMagneticModelApp

Instructions

To generate the publication figures, run the MATLAB live script named "Figures.mlx".

To run the simulation interactively, run the MATLAB script named "RunAxesmFigure.m".

The agent is controlled by directly setting its parameter matrix, e.g., agent.A = [1, 0; 0, 1], and with these commands:

• agent.SetStart, without arguments (an interactive targeting reticule will appear), or with arguments lat, lon specifying the precise start location
• agent.SetGoal, without arguments (an interactive targeting reticule will appear), or with arguments lat, lon specifying the precise goal location
• agent.Step, without arguments (one step will be taken), or with argument n specifying the number of steps
• agent.Reset, which clears the trajectory and resets the agent to the start
• agent.Run, which performs a reset and takes steps until a terminating condition is reached

Try these commands to see their effects on the map:

• g.SetLevelCurves(level_curves_type), where level_curves_type is one of

  • "contours"
  • "none"
  • "nullclines"
  • "parallelgradients"

• g.SetSurfaceMesh(surface_mesh_type), where surface_mesh_type is one of

  • "orthogonality"
  • "stability"
  • "terrain"
  • "topography"

• g.SetVectorField(vector_field_type, downsample_factor, gradients_scale), where vector_field_type is one of

  • "flow"
  • "gradients"
  • "none"

  where downsample_factor controls the density of the vector field, and where gradients_scale controls the size of vectors when the type is "gradients"