---
toc: false
title: Electronic Stability Control based on FMCSA571.126
...

Overview
========

Initial and informal model based on first reading of the [US Electronic Stability Control](www.fmcsa.dot.gov/rules-regulations/administration/fmcsr/fmcsrruletext.aspx?reg=571.126) standard.


```{.clafer .summary}
```

Detailed Model
==============

```clafer
abstract degree ->> integer
    [ this > 0 && this <= 360 ]
```

```clafer
abstract Vehicle
    `DriveConfiguration
    `ElectronicStabilityControlSystem
    `AntiLockBreakSystem
    `TractionControlSystem
    AckermanSteerAngle : degree
    speed -> integer
    lateralAcceleration -> integer
    sideSlipAngle : degree
    yawRate : degree
    normalYawRate : degree
        givenAckermanSteerAngle
    hasOversteer ?
    [yawRate > normalYawRate <=> hasOversteer ]
    hasUndersteer ?
    [yawRate < normalYawRate <=> hasUndersteer ]
    GVWR -> integer
```

```clafer
abstract xor DriveConfiguration
    twoWheelDrive
    frontWheelDrive
    rearWheelDrive
    allWheelDrive
    xor fourWheelDrive
        highGearWithLockedDifferential
        lowGear
```


```clafer
abstract ElectronicStabilityControlSystem
    vehicle -> Vehicle
    augmentsVehiclesDirectionalStability
        adjustsBrakeTorquesToInduceCorrectingYawMoment
            toEachWheelIndividually
    limits
       understeer
       oversteer
    estimates
        YawRate
        sideSlip 
            derivativeWithRespectToTime
    monitors 
        driverSteeringInputs
        modifiesEngineTorque
    isOperational ?
        [ vehicle.speed > 20 ]
        duringAllPhasesOfDriving
            acceleration
            coasting
            deceleration
            breaking
        withAntiLockBrakeSystem
        withTractionControlSystem
    or isNotOperational
        whenTurnedOffByTheDriver ?
        whenDrivenInReverse ?
        duringSystemInitialization ?
    Mode
        driverSelected ?
        xor type
            standard // (default)
            performance
            snowOrSlipperyRoad
            Off
    entersStandardModeAfterIgnition
    satisfies
        stabilityCriteria
        responsivenessCriterion
    or MalfunctionTelltale ?
        malfunctionDetected
            mustRemainContinuouslyIlluminatedForAsLongAsMalfunctionExists
        ignitionLockInOnPosition
        mustExtinguishAtTheNextIgnitionCycleAfterTheMalfunctionHasBeenCorrected
        flashingWhenInOperation ?
        mustIlluminateWhenIgnitionControlInCheckPosition
    SystemControls
        Off
        xor ignitionControlPosition
            Off
            Check
            On
            Start

abstract AntiLockBreakSystem

abstract TractionControlSystem
```