OptSim

OptSim is BobDyn/BobSim's sensitivity and response-surface lane. It creates vehicle variants, runs selected analysis workflows, and aggregates metrics into tables and reports.

Use OptSim when the question is not just "what does this one vehicle do?" but:

• which parameters dominate a metric
• how sensitive the vehicle is to a change
• which regions deserve higher-fidelity simulation
• where a trade-off begins
• which inputs should be used for a refined response surface

Current status

OptSim is useful release infrastructure, but it is intentionally narrower than StandardSim. Treat StandardSim and EnvelopeSim as the primary public baseline workflows, and use OptSim for sensitivity studies around those baselines.

Layout

Path	Role
_4_OptSim/StandardSens/	StandardSim sensitivity and response-surface workflow
_4_OptSim/StandardSens/configs/vehicle_architecture.yaml	Human-edited architecture and sweep source
_4_OptSim/StandardSens/configs/_doe_config.yaml	Generated DOE config
_4_OptSim/StandardSens/configs/compiler_config.yaml	Compile/run settings
_4_OptSim/StandardSens/configs/aggregator_config.yaml	Metric extraction map
_4_OptSim/StandardSens/pipeline/	Sampling, generation, compile/run, aggregation, plotting helpers
_4_OptSim/EnvelopeSens/	Reduced EnvelopeSim sensitivity workflow
_4_OptSim/EnvelopeSens/config.yml	Envelope sensitivity config
_4_OptSim/Build/	Generated variants, intermediate outputs, and private build artifacts
_4_OptSim/results/	Public sensitivity and response-surface outputs

Commands

make opt-standard
make opt-envelope
make opt-refined

Command	Purpose
make opt-standard	Run StandardSim pre-screen sensitivities
make opt-envelope	Run EnvelopeSim sensitivities
make opt-refined	Build refined StandardSim response surfaces from sensitivity results

For interactive work:

make shell-opt

Standard Sensitivities

make opt-standard runs _4_OptSim/StandardSens/pre_screen_sensitivities.py.

The workflow:

1. Samples and generates vehicle variants.
2. Builds and simulates StandardSim variants.
3. Aggregates StandardSim metrics.
4. Writes a public sensitivity table.
5. Plots StandardSim tornado diagrams.

Useful outputs:

_4_OptSim/Build/StandardSens/standard_sensitivity_inputs.csv
_4_OptSim/Build/StandardSens/standard_sensitivity_results.parquet
_4_OptSim/results/standard_sensitivity_results.csv
_4_OptSim/results/standard_sensitivity_report.pdf

The public CSV joins sampled inputs with selected StandardSim metrics so the relationship between design variables and vehicle response remains inspectable.

Envelope Sensitivities

make opt-envelope runs _4_OptSim/EnvelopeSens/sensitivities.py.

The workflow:

1. Generates EnvelopeSim variants.
2. Writes input and scope tables.
3. Runs GGV/YMD-style reduced sensitivity metrics.
4. Computes relative sensitivities.
5. Writes a public report and results CSV.

Useful outputs:

_4_OptSim/Build/EnvelopeSens/envelope_sensitivity_inputs.csv
_4_OptSim/Build/EnvelopeSens/envelope_sensitivity_scope.csv
_4_OptSim/Build/EnvelopeSens/envelope_relative_sensitivities.csv
_4_OptSim/results/envelope_sensitivity_results.csv
_4_OptSim/results/envelope_sensitivity_report.pdf

Refined Response Surfaces

make opt-refined runs _4_OptSim/StandardSens/refined_response_surfaces.py.

The workflow uses StandardSim sensitivity results to select influential inputs, then builds a refined population for response-surface fitting.

Useful outputs:

_4_OptSim/results/refined_response_surface_results.csv

The script can also write selection tables, coefficient tables, and response surface PDFs depending on the configured arguments and available prior results.

Architecture Config

The human-edited StandardSens source is:

_4_OptSim/StandardSens/configs/vehicle_architecture.yaml

It selects the vehicle template, sampling strategy, sample count or interval count, random seed, and sweep variables.

Each variable maps a high-level design path to a parameter inside the variant Modelica record:

Field	Meaning
path	Stable design-variable name used in sampled rows and aggregate output
block	Modelica parameter record block in the baseline .mo file
param	Parameter inside that block
range	Sample range for that variable
label	Optional human-readable label used by sensitivity plots
values	Optional explicit interval values
targets	Optional linked Modelica parameters updated together
scale	Optional scale factor between design variable and Modelica value

Variant 0 is the baseline. Interval-splice studies perturb one input at a time around that baseline, which is what the tornado reports expect.

Generated Variants

StandardSens generated variants live under:

_4_OptSim/Build/StandardSens/population/

Each variant can contain:

variant.mo
build/<standard>/
results/<standard>/
run_error_<standard>.log

These are intentionally inspectable Modelica record artifacts. If a sensitivity result looks suspicious, start by opening the relevant variant.mo, then check the run log and metrics CSV.

Cleanup

If sample counts, variable dimensions, or response-surface selections change, clean OptSim artifacts before rerunning:

make clean-opt

For a full release cleanup:

make clean-all

Failure Modes

Symptom	Likely cause
BobLib not found	Submodule missing; run make init
Population mismatch	Sample count changed without cleaning OptSim build artifacts
Selected architecture mismatch	Standard model imports a different baseline record or template
Compile failure	Variant produced an invalid or difficult Modelica record
Missing metrics CSV	Simulation failed or report wrapper did not finish
Partial metrics CSV	Run crashed during write; rerun after inspecting the failure log