BobSim App

The BobSim app is the primary user interface for local vehicle setup, simulation launch, result review, and saved run organization.

There are two normal launch paths.

For the released desktop app, download the BobSim asset for your operating system from the GitHub Release, extract it, and run BobSim. The desktop app bundles the Python backend and frontend in an embedded desktop window. It does not bundle OpenModelica or prebuilt simulation executables; those are selected and built locally on the user's machine.

For a source checkout, start it from the BobSim root:

make app

Then open:

http://127.0.0.1:8765

Use a direct command when you need a different host or port:

python -m _5_App.app --host 127.0.0.1 --port 8766

Desktop Runtime Data

The desktop app seeds a writable BobSim runtime workspace on first launch. User vehicles, generated Modelica definitions, local OpenModelica builds, saved configs, and saved results live there instead of inside the downloaded executable.

Default runtime roots:

Platform	Default runtime root
Windows	%LOCALAPPDATA%\BobDyn\BobSim
macOS	~/Library/Application Support/BobDyn/BobSim
Linux	${XDG_DATA_HOME:-~/.local/share}/BobDyn/BobSim

Set BOBSIM_HOME to choose a different runtime root. BOBDYN_HOME is still honored for compatibility with earlier local builds.

On launch, the desktop app refreshes app-owned runtime resources from the bundle, including BobLib resources, report helpers, build scripts, and default run configs. User-owned files such as saved vehicles, active workspaces, saved results, saved configs, and imported templates are preserved.

What The App Owns

The app wraps the existing BobSim workflow code. It does not replace the CLI targets; it gives the normal setup and run path a guided browser surface.

Area	App responsibility
Vehicle setup	Load, create, import, edit, preview, save, and write vehicle definitions
Modelica stack status	Show BobLib, generated vehicle definition, VehicleSim, and FourPostSim readiness
Simulation launch	Configure workflows, apply edits, build, run, and stream job logs
Result review	Preview registered outputs and download archived run packages
Local libraries	Manage saved vehicles, saved run configs, local run archives, and vehicle workspaces

Setup

Setup is the first stop. The startup dialog offers:

Option	Source
Load Vehicle	Saved vehicles in _5_App/vehicle_configs/
Create Vehicle	Architecture templates from _0_Utils/vehicle_templates/
Import YAML	A user-selected .yml or .yaml file
Continue Active File	The currently active vehicle data

After a vehicle opens, the guided setup path is:

Architecture -> Geometry -> Mass -> Suspension -> Compliances -> Tires -> Aero -> Powertrain

The editor pane exposes the active fields. The preview pane shows the vehicle geometry, hardpoints, mass properties, tire curves, aero maps, suspension linkage behavior, and powertrain layout. The ? button opens the active step's short reference panel.

Before running simulations:

1. Click Save Vehicle.
2. Click Write to MBD.
3. Confirm the top status strip shows the vehicle definition as current.

Write to MBD generates the Modelica stack that the standard simulation workflows build and run.

Simulation

Simulation is the StandardSim launch surface.

Workflow	What it runs
Ramp Steer	RampSteerEval using the active VehicleSim definition
Steady State	SteadyStateEval settled target lateral-acceleration cases
Transient	TransientEval step and sine steering cases
Four Post	FourPostEval heave, roll, and vertical-force procedures

Each workflow card opens a configuration modal. The modal has:

Control	Use
Configure tab	Edit the workflow's supported run fields
Run config picker	Load saved or default run configs
Save Config	Store a reusable app-side run config
Apply Edits	Apply in-browser changes before running
Build + Run or Run	Launch the workflow actions
Run Log tab	Follow job output and inspect recent jobs

Standard workflows that need a Modelica executable will build it when launched from the card. The run log is the first place to look for OpenModelica, dependency, or simulation failures.

The Ramp Steer config exposes the nonlinear steering-gain-loss cutoff used to stop open-loop ramps before the response becomes strongly nonlinear. The Steady State config exposes velocity-specific lateral-acceleration caps and the main closed-loop settle tolerances. The default caps are intentionally conservative for alpha releases so the public run grid completes cleanly; users can raise or remove caps for exploratory runs.

OpenModelica Toolchain

Simulation is available after BobSim verifies an OpenModelica toolchain. The app auto-detects common installs, then exposes a toolchain selector when manual selection is needed.

Select:

Field	Use
omc executable	The OpenModelica compiler executable, or its bin directory
Library directory	Directory containing packages such as Modelica and VehicleInterfaces

BobSim only requires a verified omc executable and an OpenModelica library directory. Linux system installs usually do not need an OpenModelica home path.

Common library defaults:

Platform	Typical library directory
Windows	%APPDATA%\.openmodelica\libraries
macOS	~/.openmodelica/libraries
Linux	~/.openmodelica/libraries

The selector verifies omc --version and checks that required libraries are present before Simulation unlocks.

Archive

Archive is the local history of completed Simulation runs. It is focused on downloadable artifacts instead of in-app plotting.

After a Simulation job succeeds, BobSim automatically creates a local archive package for that vehicle/workflow. Each package includes:

• the generated PDF report
• the metrics CSV
• a signal archive zip organized by run
• a run description manifest
• vehicle and run-config snapshots

The report includes the configured summary/plot pages. FourPostEval omits the raw time-series appendix by default so the K&C report stays focused; workflows can still opt into raw appendix pages through their report config. The signal archive contains per-run signals.csv, overrides.txt, run.log, and description.json files when those run artifacts are available.

Archive cards include Delete for removing local runs. Deleting an archive removes both the global saved package and the mirrored vehicle workspace copy.

Local App Paths

Path	Contents
_5_App/static/	Browser UI assets
_5_App/app.py	Local Python web server and API
_5_App/vehicle_configs/	Saved app vehicle YAML files
_5_App/sim_configs/	Default and saved app run configs
_5_App/vehicle_workspaces/	Per-vehicle generated config and result workspaces
_5_App/saved_results/	Local archive packages saved from the app
_3_StandardSim/generated_results/	Standard outputs registered by the app

Older CLI outputs remain available on disk, but the alpha app UI focuses on local archive packages instead of the full CSV explorer.

CLI Compatibility

Everything the app runs is still backed by repository code and files. Use the CLI when you need automation:

make standard-eval-ramp-steer
make standard-eval-steady-state
make standard-eval-transient
make standard-eval-four-post

Use the app when you want the guided path:

Setup -> Save Vehicle -> Write to MBD -> Simulation -> Archive

Troubleshooting

Simulation is disabled

Save the vehicle, click Write to MBD, and verify the OpenModelica toolchain. Simulation is locked until the saved vehicle definition is current and the external toolchain is ready.

Write to MBD is disabled

Hover the button for the reason. Common causes are missing BobLib submodule, unsaved vehicle edits, or no active vehicle.

No module named yaml

Install BobSim Python requirements in the environment that launches the app:

python -m pip install -r requirements.txt

omc: command not found

Open Simulation's OpenModelica toolchain selector and choose the omc executable plus the library directory. If you are using the source checkout, scripted CLI workflows can also run from the Docker environment.

No output appears in Archive

Open Run Log first. A failed build or simulation usually leaves the useful message there. Also check that the workflow's report and metrics output paths match the files written by the active config.