injector_model.cpp

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#include "pch.h"
 
#include "injector_model.h"
#include "fuel_computer.h"
 
void InjectorModelBase::prepare() {
    float flowRatio = getInjectorFlowRatio();
 
    // "large pulse" flow rate
    m_massFlowRate = flowRatio * getBaseFlowRate();
    m_deadtime = getDeadtime();
 
    if (getNonlinearMode() == INJ_FordModel) {
        m_smallPulseFlowRate = flowRatio * getSmallPulseFlowRate();
        m_smallPulseBreakPoint = getSmallPulseBreakPoint();
 
        // amount added to small pulses to correct for the "kink" from low flow region
        m_smallPulseOffset = 1000 * ((m_smallPulseBreakPoint / m_massFlowRate) - (m_smallPulseBreakPoint / m_smallPulseFlowRate));
    }
}
 
constexpr float convertToGramsPerSecond(float ccPerMinute) {
    return ccPerMinute * (fuelDensity / 60.f);
}
 
// returns: grams per second flow
float InjectorModelWithConfig::getBaseFlowRate() const {
    if (engineConfiguration->injectorFlowAsMassFlow) {
        return m_cfg->flow;
    } else {
        return convertToGramsPerSecond(m_cfg->flow);
    }
}
 
float InjectorModelPrimary::getSmallPulseFlowRate() const {
    return engineConfiguration->fordInjectorSmallPulseSlope;
}
 
float InjectorModelPrimary::getSmallPulseBreakPoint() const {
    // convert milligrams -> grams
    // todo: make UI deal with scaling?!
    return 0.001f * engineConfiguration->fordInjectorSmallPulseBreakPoint;
}
 
InjectorNonlinearMode InjectorModelPrimary::getNonlinearMode() const {
    return engineConfiguration->injectorNonlinearMode;
}
 
injector_compensation_mode_e InjectorModelPrimary::getInjectorCompensationMode() const {
    return engineConfiguration->injectorCompensationMode;
}
 
float InjectorModelPrimary::getFuelReferencePressure() const {
    return engineConfiguration->fuelReferencePressure;
}
 
float InjectorModelSecondary::getSmallPulseFlowRate() const {
    // not supported on second bank
    return 0;
}
 
float InjectorModelSecondary::getSmallPulseBreakPoint() const {
    // not supported on second bank
    return 0;
}
 
injector_compensation_mode_e InjectorModelSecondary::getInjectorCompensationMode() const {
    return engineConfiguration->secondaryInjectorCompensationMode;
}
 
float InjectorModelSecondary::getFuelReferencePressure() const {
    return engineConfiguration->secondaryInjectorFuelReferencePressure;
}
 
InjectorNonlinearMode InjectorModelSecondary::getNonlinearMode() const {
    // nonlinear not supported on second bank
    return InjectorNonlinearMode::INJ_None;
}
 
void InjectorModelWithConfig::updateState() {
    // TODO: remove at the end of 2025
    // hack not to break tunes before 2779925f54f5c2d23499cbb2797f71508c652f54 "injector lag lookup should be done based on differential pressure"
    if (engineConfiguration->useAbsolutePressureForLagTime) {
        pressureCorrectionReference = getFuelPressure().Value;
    } else {
        pressureCorrectionReference = getFuelDifferentialPressure().Value;
    }
}
 
expected<float> InjectorModelWithConfig::getFuelPressure() const {
  return getFuelDifferentialPressure().Value + Sensor::get(SensorType::Map).value_or(STD_ATMOSPHERE);
}
 
expected<float> InjectorModelWithConfig::getFuelDifferentialPressure() const {
    auto map = Sensor::get(SensorType::Map);
    auto baro = Sensor::get(SensorType::BarometricPressure);
 
    float baroKpa = baro.Value;
    // todo: extract baro sensor validation logic
    if (!baro || baro.Value > 120 || baro.Value < 50) {
        baroKpa = STD_ATMOSPHERE;
    }
 
    switch (getInjectorCompensationMode()) {
        case ICM_FixedRailPressure:
            // Add barometric pressure, as "fixed" really means "fixed pressure above atmosphere"
            return getFuelReferencePressure()
                + baroKpa
                - map.value_or(STD_ATMOSPHERE);
        case ICM_SensedRailPressure: {
            if (!Sensor::hasSensor(SensorType::FuelPressureInjector)) {
                warning(ObdCode::OBD_Fuel_Pressure_Sensor_Missing, "Fuel pressure compensation is set to use a pressure sensor, but none is configured.");
                return unexpected;
            }
 
            auto fps = Sensor::get(SensorType::FuelPressureInjector);
 
            // TODO: what happens when the sensor fails?
            if (!fps) {
                return unexpected;
            }
 
            switch (engineConfiguration->fuelPressureSensorMode) {
                case FPM_Differential:
                    // This sensor directly measures delta-P, no math needed!
                    return fps.Value;
                case FPM_Gauge:
                    if (!map) {
                        return unexpected;
                    }
 
                    return fps.Value + baroKpa - map.Value;
                case FPM_Absolute:
                default:
                    if (!map) {
                        return unexpected;
                    }
 
                    return fps.Value - map.Value;
            }
        } default: return unexpected;
    }
}
 
float InjectorModelWithConfig::getInjectorFlowRatio() {
    // Compensation disabled, use reference flow.
    auto compensationMode = getInjectorCompensationMode();
    if (compensationMode == ICM_None || compensationMode == ICM_HPFP_Manual_Compensation) {
        return 1.0f;
    }
 
    const float referencePressure = getFuelReferencePressure();
 
    if (referencePressure < 50) {
        // impossibly low fuel ref pressure
        criticalError("Impossible fuel reference pressure: %f", referencePressure);
 
        return 1.0f;
    }
 
    expected<float> diffPressure = getFuelDifferentialPressure();
 
    // If sensor failed, best we can do is disable correction
    if (!diffPressure) {
        return 1.0f;
    }
 
    pressureDelta = diffPressure.Value;
 
    // Somehow pressure delta is less than 0, assume failed sensor and return default flow
    if (pressureDelta <= 0) {
        return 1.0f;
    }
 
    pressureRatio = pressureDelta / referencePressure;
    // todo: live data model?
    float flowRatio = sqrtf(pressureRatio);
 
    // TODO: should the flow ratio be clamped?
    return flowRatio;
}
 
float InjectorModelWithConfig::getDeadtime() const {
    return interpolate3d(
        m_cfg->battLagCorrTable,
        m_cfg->battLagCorrPressBins, pressureCorrectionReference,
        m_cfg->battLagCorrBattBins, Sensor::get(SensorType::BatteryVoltage).value_or(VBAT_FALLBACK_VALUE)
    );
}
 
//TODO: only used in the tests, refactor pending to InjectorModelWithConfig
floatms_t InjectorModelBase::getInjectionDuration(float fuelMassGram) const {
    if (fuelMassGram <= 0) {
        // If 0 mass, don't do any math, just skip the injection.
        return 0.0f;
    }
 
    // Get the no-offset duration
    floatms_t baseDuration = getBaseDurationImpl(fuelMassGram);
 
    return baseDuration + m_deadtime;
}
 
floatms_t InjectorModelWithConfig::getInjectionDuration(float fuelMassGram) const {
    if (fuelMassGram <= 0) {
        // If 0 mass, don't do any math, just skip the injection.
        return 0.0f;
    }
 
  // hopefully one day we pick between useInjectorFlowLinearizationTable and ICM_HPFP_Manual_Compensation approaches
  // and not more than one of these would stay
    if (engineConfiguration->useInjectorFlowLinearizationTable) {
      auto fps = Sensor::get(SensorType::FuelPressureInjector);
    // todo: KPA vs BAR mess?!
    return interpolate3d(config->injectorFlowLinearization,
            config->injectorFlowLinearizationPressureBins, KPA2BAR(fps.Value),// array values are on bar
            config->injectorFlowLinearizationFuelMassBins, fuelMassGram * 1000);  // array values are on mg
    }
 
    // Get the no-offset duration
    floatms_t baseDuration = getBaseDurationImpl(fuelMassGram);
 
    // default non GDI case
    if (getInjectorCompensationMode() != ICM_HPFP_Manual_Compensation) {
        // Add deadtime offset
        return baseDuration + m_deadtime;
    }
 
    if (!Sensor::hasSensor(SensorType::FuelPressureHigh)) {
        return baseDuration + m_deadtime;
    }
 
    auto fps = Sensor::get(SensorType::FuelPressureHigh);
    // todo: KPA vs BAR mess in code and UI?!
    float fuelMassCompensation = interpolate3d(config->hpfpFuelMassCompensation,
            config->hpfpFuelMassCompensationFuelPressure, KPA2BAR(fps.Value),// array values are on bar
            config->hpfpFuelMassCompensationFuelMass, fuelMassGram * 1000);  // array values are on mg
 
    // recalculate base duration with fuel mass compensation
    baseDuration =  getBaseDurationImpl(fuelMassGram * fuelMassCompensation);
    return baseDuration + m_deadtime;
}
 
float InjectorModelBase::getFuelMassForDuration(floatms_t duration) const {
    // Convert from ms -> grams
    return duration * m_massFlowRate * 0.001f;
}
 
// todo: all that *1000 and *0.001f is pretty annoying, we need a cleaner approach for units!
floatms_t InjectorModelBase::getBaseDurationImpl(float fuelMassGram) const {
    floatms_t baseDuration = fuelMassGram / m_massFlowRate * 1000;
 
    switch (getNonlinearMode()) {
    case INJ_FordModel:
        if (fuelMassGram < m_smallPulseBreakPoint) {
            // Small pulse uses a different slope, and adds the "zero fuel pulse" offset
            return (fuelMassGram / m_smallPulseFlowRate * 1000) + m_smallPulseOffset;
        } else {
            // Large pulse
            return baseDuration;
        }
    case INJ_PolynomialAdder:
        return correctInjectionPolynomial(baseDuration);
    case INJ_None:
    default:
        return baseDuration;
    }
}
 
floatms_t InjectorModelBase::correctInjectionPolynomial(floatms_t baseDuration) const {
    if (baseDuration > engineConfiguration->applyNonlinearBelowPulse) {
        // Large pulse, skip correction.
        return baseDuration;
    }
 
    auto& is = engineConfiguration->injectorCorrectionPolynomial;
    float xi = 1;
 
    float adder = 0;
 
    // Add polynomial terms, starting with x^0
    for (size_t i = 0; i < efi::size(is); i++) {
        adder += is[i] * xi;
        xi *= baseDuration;
    }
 
    return baseDuration + adder;
}
 
InjectorModelWithConfig::InjectorModelWithConfig(const injector_s* const cfg)
    : m_cfg(cfg)
{
}
 
InjectorModelPrimary::InjectorModelPrimary()
    : InjectorModelWithConfig(&engineConfiguration->injector)
{
}
 
// TODO: actual separate config for second bank!
InjectorModelSecondary::InjectorModelSecondary()
    : InjectorModelWithConfig(&engineConfiguration->injectorSecondary)
{
}