Conventional Vehicle Demo

This demo simulates a conventional vehicle over a drive cycle and visualizes the fuel converter and road load behavior.

import os
from pathlib import Path

import matplotlib.pyplot as plt
import seaborn as sns

import fastsim as fsim

sns.set_theme()

# if environment var `SHOW_PLOTS=false` is set, no plots are shown
SHOW_PLOTS = os.environ.get("SHOW_PLOTS", "true").lower() == "true"
# if environment var `SAVE_FIGS=true` is set, save plots
SAVE_FIGS = os.environ.get("SAVE_FIGS", "false").lower() == "true"

Setup and Simulation¶

Load a vehicle and drive cycle, configure per-step state recording, run the simulation, and extract the results.

# load 2012 Ford Fusion from file
veh = fsim.Vehicle.from_resource("2012_Ford_Fusion.yaml")

# Set `save_interval` at vehicle level -- cascades to all sub-components with time-varying states
veh.set_save_interval(1)

# load cycle from file
cyc = fsim.Cycle.from_resource("udds.csv")

# instantiate `SimDrive` simulation object
sd = fsim.SimDrive(veh, cyc)
sd.walk()

df = sd.to_dataframe()
sd_dict = sd.to_pydict(flatten=True)

Visualize Results¶

The following plots show fuel converter and road load behavior over the drive cycle.

def plot_fc_pwr():
    """Plot fuel converter powers"""
    fig, ax = plt.subplots(2, 1, sharex=True, figsize=(10, 6))
    plt.suptitle("Fuel Converter Power")

    ax[0].plot(
        df["cyc.time_seconds"],
        (
            df["veh.pt_type.Conv.fc.history.pwr_prop_watts"]
            + df["veh.pt_type.Conv.fc.history.pwr_aux_watts"]
        )
        / 1e3,
        label="shaft",
    )
    ax[0].plot(
        df["cyc.time_seconds"],
        df["veh.pt_type.Conv.fc.history.pwr_fuel_watts"] / 1e3,
        label="fuel",
    )
    ax[0].set_ylabel("FC Power [kW]")
    ax[0].legend()

    ax[1].plot(
        df["cyc.time_seconds"],
        df["veh.history.speed_ach_meters_per_second"],
    )
    ax[1].set_xlabel("Time [s]")
    ax[1].set_ylabel("Ach Speed [m/s]")

    plt.tight_layout()
    if SAVE_FIGS:
        plt.savefig(Path("./plots/fc_pwr.svg"))
    if SHOW_PLOTS:
        plt.show()

    return fig, ax

Fuel converter output power (drivetrain + auxiliary) and fuel input power over the drive cycle.

fig, ax = plot_fc_pwr()

def plot_fc_energy():
    """Plot fuel converter energies"""
    fig, ax = plt.subplots(2, 1, sharex=True, figsize=(10, 6))
    plt.suptitle("Fuel Converter Energy")

    ax[0].plot(
        df["cyc.time_seconds"],
        (
            df["veh.pt_type.Conv.fc.history.energy_prop_joules"]
            + df["veh.pt_type.Conv.fc.history.energy_aux_joules"]
        )
        / 1e6,
        label="shaft",
    )
    ax[0].plot(
        df["cyc.time_seconds"],
        df["veh.pt_type.Conv.fc.history.energy_fuel_joules"] / 1e6,
        label="fuel",
    )
    ax[0].set_ylabel("FC Energy [MJ]")
    ax[0].legend()

    ax[1].plot(
        df["cyc.time_seconds"],
        df["veh.history.speed_ach_meters_per_second"],
    )
    ax[1].set_xlabel("Time [s]")
    ax[1].set_ylabel("Ach Speed [m/s]")

    plt.tight_layout()
    if SAVE_FIGS:
        plt.savefig(Path("./plots/fc_energy.svg"))
    if SHOW_PLOTS:
        plt.show()

    return fig, ax

Cumulative fuel converter output energy (drivetrain + auxiliary) and fuel input energy over the drive cycle.

fig, ax = plot_fc_energy()

def plot_road_loads():
    """Plot road loads"""
    fig, ax = plt.subplots(2, 1, sharex=True, figsize=(10, 6))
    plt.suptitle("Road Loads")

    ax[0].plot(
        df["cyc.time_seconds"],
        df["veh.history.pwr_drag_watts"] / 1e3,
        label="drag",
    )
    ax[0].plot(
        df["cyc.time_seconds"],
        df["veh.history.pwr_rr_watts"] / 1e3,
        label="rolling resistance",
    )
    ax[0].set_ylabel("Power [kW]")
    ax[0].legend()

    ax[1].plot(
        df["cyc.time_seconds"],
        df["veh.history.speed_ach_meters_per_second"],
    )
    ax[1].set_xlabel("Time [s]")
    ax[1].set_ylabel("Ach. Speed [m/s]")

    plt.tight_layout()
    if SAVE_FIGS:
        plt.savefig(Path("./plots/road_loads.svg"))
    if SHOW_PLOTS:
        plt.show()

    return fig, ax

Aerodynamic drag power and rolling resistance power over the drive cycle.

fig, ax = plot_road_loads()

Source: fastsim/docs/demo_scripts/powertrains/demo_conv.py