StandardSim

StandardSim is BobDyn/BobSim's high-fidelity simulation lane. It runs BobDyn/BobLib Modelica executables through Python workflows that define cases, run the solver, extract signals, compute metrics, and build engineering reports.

The clearest launch surface is the app's Simulation view. Use the CLI targets when you want scripted or Docker-backed runs.

The active StandardSim area lives under:

_3_StandardSim/

Structure

Path	Role
_3_StandardSim/build_vehicle_sim.mos	OpenModelica build script for VehicleSim
_3_StandardSim/build_four_post_sim.mos	OpenModelica build script for FourPostSim
_3_StandardSim/_modelica_runner.py	Shared OpenModelica executable runner
_3_StandardSim/RampSteerEval/	Open-loop ramp-steer workflow
_3_StandardSim/SteadyStateEval/	Settled target lateral-acceleration workflow
_3_StandardSim/TransientEval/	Step and sine transient workflow
_3_StandardSim/FourPostEval/	Heave and roll four-post workflow
_3_StandardSim/BuildBobLib/	OpenModelica executables and generated build artifacts
_3_StandardSim/results/	Public reports and metrics CSVs
_3_StandardSim/generated_results/	App-registered reports and metrics CSVs

App Workflows

Open Simulation in the app after Setup, Save Vehicle, and Write to MBD.

App card	Workflow	Use it for
Ramp Steer	RampSteerEval	Open-loop steering ramp response
Steady State	SteadyStateEval	Settled lateral-acceleration operating points
Transient	TransientEval	Step steer and continuous sine response
Four Post	FourPostEval	Heave, roll, and vertical-force suspension procedures

Each card opens a run modal with editable config fields, saved config controls, Build + Run, and Run Log.

Build Targets

Command	Builds	Output directory
make standard-build	BobLib.Experiments.Standards.VehicleSim	_3_StandardSim/BuildBobLib/VehicleSim/
make standard-build-four-post	BobLib.Experiments.Standards.FourPostSim	_3_StandardSim/BuildBobLib/FourPostSim/

Both targets compile the active generated BobLib Modelica entry point. The build scripts create the target directories before buildModel(...), and the app also ensures the directories exist before invoking OpenModelica.

Run Targets

Command	Workflow	Main config
make standard-eval-ramp-steer	Open-loop ramp-steer characterization	_3_StandardSim/RampSteerEval/ramp_steer_eval_config.yml
make standard-eval-steady-state	Steady-state cornering characterization	_3_StandardSim/SteadyStateEval/steady_state_eval_config.yml
make standard-eval-transient	Step steer and continuous sine response	_3_StandardSim/TransientEval/transient_eval_config.yml
make standard-eval-four-post	Suspension/chassis heave and roll sweeps	_3_StandardSim/FourPostEval/four_post_eval_config.yml
make standard-eval-all	All standard evaluations	All four configs above

Direct Python module entry points are still available for development:

python -m _3_StandardSim.RampSteerEval.ramp_steer_eval_sim
python -m _3_StandardSim.SteadyStateEval.steady_state_eval_sim
python -m _3_StandardSim.TransientEval.transient_eval_sim
python -m _3_StandardSim.FourPostEval.four_post_eval_sim

Prefer the make targets for public workflows because they rebuild missing executables automatically.

Shared Runner

_3_StandardSim/_modelica_runner.py is the shared execution layer.

For each case it:

1. Creates a run directory under the relevant build tree.
2. Writes overrides.txt with Modelica parameter overrides.
3. Runs the compiled OpenModelica executable.
4. Applies solver, time, output, event, log, and extra runtime flags.
5. Reads the generated CSV result file.
6. Extracts raw time histories or final steady values.
7. Preserves case metadata.
8. Removes the run directory when execution.cleanup: true.

The runner expects these files to exist:

<build_dir>/<exec_name>
<build_dir>/<exec_name>_init.xml

If either file is missing, rerun the matching build target.

On Windows the executable may be written with an .exe suffix. BobSim checks for both forms.

RampSteerEval

RampSteerEval characterizes open-loop steering ramp behavior using the unified VehicleSim executable.

Use it when you want a first handling proof path from the app or CLI. It sweeps configured velocity cases, applies a handwheel ramp, records the vehicle response, and writes report metrics from the measured lateral-acceleration path.

Current config highlights:

Key	Current role
simulation.exec_name	BobLib.Experiments.Standards.VehicleSim
simulation.build_dir	_3_StandardSim/BuildBobLib/VehicleSim
simulation.init_parameters.useMode	0, open-loop ramp steer
simulation.init_parameters.enableLinearityTermination	enables the steering-gain-loss ramp cutoff
simulation.init_parameters.linearityNonlinearityFraction	local lateral-gain loss fraction that stops the ramp
simulation.init_parameters.linearityReferenceAy	reference measured lateral acceleration before cutoff evaluation
sweep.testVels	velocity isolines
sweep.maxAy	positive ramp target used to choose the ramp direction and report range
fit.ay_linear_max	linear fit band upper bound

The app exposes the nonlinearity cutoff controls in the Ramp Steer run config modal. If higher-speed ramp-steer runs stop before the desired lateral acceleration, increase the cutoff fraction or disable the cutoff for that run.

Main outputs:

_3_StandardSim/generated_results/ramp_steer_eval_report.pdf
_3_StandardSim/generated_results/ramp_steer_eval_report_metrics.csv

SteadyStateEval

SteadyStateEval characterizes quasi-steady lateral response using the unified VehicleSim executable in closed-loop target lateral-acceleration mode.

Current config highlights:

Key	Current role
simulation.exec_name	BobLib.Experiments.Standards.VehicleSim
simulation.build_dir	_3_StandardSim/BuildBobLib/VehicleSim
simulation.init_parameters.useMode	3, closed-loop target lateral acceleration
simulation.init_parameters.steadyStateSettleTimeout	timeout after the target ramp reaches its final value
simulation.init_parameters.steadyStateAyTolerance	settled lateral-acceleration tracking tolerance
simulation.init_parameters.steadyStateSpeedTolerance	settled speed tracking tolerance
simulation.extra_args	includes -jacobian=internalNumerical
sweep.testVels	12.5, 15.0, 17.5, 20.0 m/s
sweep.targetAys	available target grid up to 18.0 m/s^2
sweep.maxAyByVelocity	default per-velocity caps for feasible alpha runs
fit.ay_linear_max	linear fit band upper bound
report.metric_target_velocity_mps	velocity used for exported summary metrics

The default target list stays broad, but the default app and workflow configs cap generated steady-state cases by velocity:

Velocity	Default max target
12.5 m/s	16.0 m/s^2
15.0 m/s	10.0 m/s^2
17.5 m/s	6.0 m/s^2
20.0 m/s	4.0 m/s^2

Remove or raise a cap when intentionally exploring higher lateral acceleration targets. The app exposes these caps and the closed-loop settle tolerances in the Steady State run config modal.

The workflow extracts steering, acceleration, roll, sideslip, yaw velocity, wheel loads, handwheel torque, and controller/debug signals. It fits response curves against measured lateral acceleration and exports gradients, ranges, tracking errors, and velocity trends.

Main outputs:

_3_StandardSim/generated_results/steady_state_eval_report.pdf
_3_StandardSim/generated_results/steady_state_eval_report_metrics.csv

_3_StandardSim/results/steady_state_eval_report.pdf
_3_StandardSim/results/steady_state_eval_report_metrics.csv

TransientEval

TransientEval characterizes steering response over time using step-steer and continuous sine cases.

Current config highlights:

Key	Current role
simulation.exec_name	BobLib.Experiments.Standards.VehicleSim
simulation.extra_args	includes -jacobian=internalNumerical
test.testVel	15.0 and 20.0 m/s velocity groups
test.run_step	enables representative step-steer cases
test.run_continuous_sine	enables sustained sine sweeps
test.steerStep_deg	5.0 degree step input
test.sweep_freq_hz	0.5, 0.75, 1.0 Hz
test.sweep_amp_deg	5.0 degree sine amplitude
test.n_cycles	4 cycles per sine run

BobLib's integrated vehicle model uses transient tire slip, with relaxation parameters supplied by each tire record. That matters most here because the workflow is explicitly measuring time-domain steering response.

Main outputs:

_3_StandardSim/generated_results/transient_eval_report.pdf
_3_StandardSim/generated_results/transient_eval_report_metrics.csv

_3_StandardSim/results/transient_eval_report.pdf
_3_StandardSim/results/transient_eval_report_metrics.csv

Representative metrics include lateral acceleration rise time, yaw-rate rise time, overshoot, gain, phase, equivalent lag, and frequency-response trends.

FourPostEval

FourPostEval evaluates suspension and chassis response through heave and roll sweeps using BobLib.Experiments.Standards.FourPostSim.

Current config highlights:

Key	Current role
simulation.exec_name	BobLib.Experiments.Standards.FourPostSim
simulation.build_dir	_3_StandardSim/BuildBobLib/FourPostSim
simulation.extra_args	includes -jacobian=internalNumerical
procedure.heaveMagnitude	0.03 m
procedure.rollMagnitude	0.02181661564992912 rad
procedure.forceMagnitude	1000 N
report.metrics_csv_path	_3_StandardSim/results/four_post_eval_report_metrics.csv
report.raw_time_series_appendix	false by default for focused K&C reports

The workflow extracts front and rear K&C output records and computes summary metrics for camber, toe, caster, KPI, mechanical trail, mechanical scrub, motion ratio, anti/jacking behavior, roll stiffness, anti-roll-bar contribution, and lateral load transfer distribution.

The Geometric Anti-Roll vs Roll report page plots the measured front and rear lateral jacking anti-roll curves across the roll sweep. Raw per-run signal data is still retained in Archive packages when the app saves a run.

Main outputs:

_3_StandardSim/generated_results/four_post_eval_report.pdf
_3_StandardSim/generated_results/four_post_eval_report_metrics.csv

_3_StandardSim/results/four_post_eval_report.pdf
_3_StandardSim/results/four_post_eval_report_metrics.csv

FourPostEval metrics are useful to EnvelopeSim. If available, the envelope loader can use the latest four-post lateral-load-transfer metric; otherwise it falls back to static front mass fraction.

Reports

Standard reports are built by _0_Utils/reporting/report_engine.py.

The report engine:

• reads the workflow config
• creates a title page
• dispatches to workflow-specific summary pages
• renders plots from the plots config
• writes a PDF with Matplotlib PdfPages

Plot pages are handled by _0_Utils/plotting/plot_engine.py.

Debugging

The fastest debugging loop for maneuver studies is:

make standard-build
make standard-eval-steady-state

For four-post work:

make standard-build-four-post
make standard-eval-four-post

If a run fails:

• Confirm the build directory contains the executable and init XML.
• Set execution.cleanup: false in the workflow config.
• Rerun the workflow.
• Inspect the retained run directory.
• Check overrides.txt, run.log, and the generated result CSV.