Improve 0-60 mph Acceleration Validation#256
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… speed loss during sustained trace-miss events by only applying a minimal epsilon reduction when the solved speed matches the previous step, instead of flooring every step. Updates acceleration test tolerances to reflect improved trace accuracy and faster acceleration behavior.
Introduces a traction-limited speed ceiling, clamping achievable speed based on tire grip rather than power output (after solver). This avoids unrealistic acceleration at low speeds caused by applying traction as a power limit, especially for FWD/RWD vehicles with dynamic weight transfer. Adds a benchmark script to compare simulated 0-60 mph times with published values, supporting validation and regression testing. Improves chassis parameter handling and serialization defaults for better robustness and data compatibility.
Introduces a benchmarking script to analyze the impact of fuel converter ramp lag and wheel friction coefficient on 0-60 mph acceleration times for reference vehicles. Enables systematic exploration of key parameters to support model calibration and validation efforts.
…AWD where necessary and drive axle weight frac = 1.0 if AWD
Reduces maximum power output parameters by 15% for several vehicle configurations to reflect updated performance assumptions or limitations. Also updates .gitignore to exclude workspace, image, and documentation files.
Introduces a benchmarking tool for comparing fuel economy across vehicle models and code revisions, enabling easier impact assessment of model changes. Updates multiple vehicle configurations to restore undereated power figures, revise chassis parameters, and correct drive types for improved modeling accuracy. Refreshes lock file to include new dependencies and updates package versions for compatibility.
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Summary
Systematic validation of FASTSim-3's 0-60 mph acceleration predictions against published test data for 39 US-market vehicles, with corrections to vehicle model parameters and traction-limiting logic.
Changes
Code Changes
fastsim-core/src/simdrive/mod.rs— Added traction-limited speed check toset_ach_speed(). Previously only power was checked to determine if the cycle was met; now the achieved speed is also bounded byspeed_trac_fwd_max(tire grip limit). This prevents vehicles from exceeding physically achievable acceleration based on available traction force.fastsim-core/src/vehicle/chassis.rs— UpdatedTryFrom(fastsim-2 → fastsim-3 conversion) to correctly inferdrive_typeanddrive_axle_weight_fracfor AWD vehicles.Vehicle YAML Corrections
drive_type: AWD,drive_axle_weight_frac: 1.0drive_type: AWD,drive_axle_weight_frac: 1.0drive_type: AWD,drive_axle_weight_frac: 1.0drive_type: AWD,drive_axle_weight_frac: 1.0,drive_axle_weight_frac: 1.0`speed_soc_fc_on_bufferfc_on_soc > max_socparameterization bug that prevented simulation from runningBenchmarking Infrastructure
benchmarks/bench_accel_0_to_60.py(new) — Comprehensive acceleration benchmark script covering 39 vehicles across all powertrain types (Conv, HEV, PHEV, BEV) with:benchmarks/bench_fe_comparison.py(new) — Fuel economy regression script to verify acceleration-related changes do not degrade EPA label fuel economy predictions.Results
Fuel economy impact: ~0.0% change for all vehicles except RAV4 Hybrid (+2.6%) and Audi A3 (−2.4%), both due to corrected drive type parameters.
Known Remaining Issues
pwr_out_max_combined_wattsparameter.