Engine Simulation

Engine Simulation

The engine and car simulated in the commuter model has the following approximate internal parameters:

    // observed transmission properties for typical turbo-diesel
    private static final double[] MPS_BY_RPM = {
            4.4704 / 2000, 8.9408 / 2000, 13.4112 / 2000, 13.4112 / 1500, 17.8816 / 1500, 22.3520 / 1500, 22.3520 / 1000
    };

    private static final double ZERO_TORQUE_RPM = 3500;

    private static final double LOW_SHIFT = 1000;
    private static final double HIGH_SHIFT = 2000;

    // The throttle has some turbo delay.
    public static final double THROTTLE_TIME_CONSTANT = 0.8;

    // in kg, not a super light car
    private static final double VEHICLE_MASS = 2000;

    // in watts (this is about 200 HP)
    private static final double MAX_POWER = 150e3;
    private static final double TORQUE_AT_ZERO = (4 * MAX_POWER / ZERO_TORQUE_RPM);

    // assuming 150 MPH absolute max speed
    private static final double DRAG_COEFFICIENT = 0.4875334;
    private static final double SHIFT_TIME = 0.1;

These give us about a 7 second 0-60MPH response and seem to give reasonable engine parameter traces.

To get a feel for how the simulated car drives, you can run a visualization which has the vehicle repeating a relatively short trip over and over again while displaying engine and geo traces by using this command

mvn exec:java -Dexec.mainClass="com.mapr.synth.drive.Trails"

Here is an example of such a trace: