speed_density.cpp

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/**
 * @file    speed_density.cpp
 *
 * See http://rusefi.com/wiki/index.php?title=Manual:Software:Fuel_Control#Speed_Density for details
 *
 * @date May 29, 2014
 * @author Andrey Belomutskiy, (c) 2012-2020
 */
 
#include "pch.h"
 
#if defined(HAS_OS_ACCESS)
#error "Unexpected OS ACCESS HERE"
#endif
 
#define rpmMin 500
#define rpmMax 8000
 
ve_Map3D_t veMap{"ve"};
 
#define tpMin 0
#define tpMax 100
 
float IFuelComputer::getTChargeCoefficient(float rpm, float tps) {
    // First, do TPS mode since it doesn't need any of the airflow math.
    if (engineConfiguration->tChargeMode == TCHARGE_MODE_RPM_TPS) {
        float minRpmKcurrentTPS = interpolateMsg("minRpm", tpMin,
                engineConfiguration->tChargeMinRpmMinTps, tpMax,
                engineConfiguration->tChargeMinRpmMaxTps, tps);
        float maxRpmKcurrentTPS = interpolateMsg("maxRpm", tpMin,
                engineConfiguration->tChargeMaxRpmMinTps, tpMax,
                engineConfiguration->tChargeMaxRpmMaxTps, tps);
 
        return interpolateMsg("Kcurr", rpmMin, minRpmKcurrentTPS, rpmMax, maxRpmKcurrentTPS, rpm);
    }
 
    constexpr floatms_t gramsPerMsToKgPerHour = (3600.0f * 1000.0f) / 1000.0f;
    // We're actually using an 'old' airMass calculated for the previous cycle, but it's ok, we're not having any self-excitaton issues
    floatms_t airMassForEngine = sdAirMassInOneCylinder * engineConfiguration->cylindersCount;
    // airMass is in grams per 1 cycle for 1 cyl. Convert it to airFlow in kg/h for the engine.
    // And if the engine is stopped (0 rpm), then airFlow is also zero (avoiding NaN division)
    floatms_t airFlow = (rpm == 0) ? 0 : airMassForEngine * gramsPerMsToKgPerHour / getEngineCycleDuration(rpm);
 
    if (engineConfiguration->tChargeMode == TCHARGE_MODE_AIR_INTERP) {
        // just interpolate between user-specified min and max coefs, based on the max airFlow value
        return interpolateClamped(
            0.0, engineConfiguration->tChargeAirCoefMin,
            engineConfiguration->tChargeAirFlowMax, engineConfiguration->tChargeAirCoefMax,
            airFlow
        );
    } else if (engineConfiguration->tChargeMode == TCHARGE_MODE_AIR_INTERP_TABLE) {
        return interpolate2d(
            airFlow,
            engineConfiguration->tchargeBins,
            engineConfiguration->tchargeValues
        );
    } else {
        criticalError("Unexpected tChargeMode: %d", engineConfiguration->tChargeMode);
        return 0;
    }
}
 
//  http://rusefi.com/math/t_charge.html
/***panel:Charge Temperature*/
temperature_t IFuelComputer::getTCharge(float rpm, float tps) {
    const auto clt = Sensor::get(SensorType::Clt);
    const auto iat = Sensor::get(SensorType::Iat);
 
    float airTemp;
 
    // Without either valid, return 0C.  It's wrong, but it'll pretend to be nice and dense, so at least you won't go lean.
    if (!iat && !clt) {
        return 0;
    } else if (!clt && iat) {
        // Intake temperature will almost always be colder (richer) than CLT - use that
        return iat.Value;
    } else if (!iat && clt) {
        // Without valid intake temperature, assume intake temp is 0C, and interpolate anyway
        airTemp = 0;
    } else {
        // All is well - use real air temp
        airTemp = iat.Value;
    }
 
    float coolantTemp = clt.Value;
 
    sdTcharge_coff = getTChargeCoefficient(rpm, tps);
 
    if (std::isnan(sdTcharge_coff)) {
        warning(ObdCode::CUSTOM_ERR_T2_CHARGE, "t2-getTCharge NaN");
        return coolantTemp;
    }
 
    // Interpolate between CLT and IAT:
    // 0.0 coefficient -> use CLT (full heat transfer)
    // 1.0 coefficient -> use IAT (no heat transfer)
    float Tcharge = interpolateClamped(0.0f, coolantTemp, 1.0f, airTemp, sdTcharge_coff);
 
    if (std::isnan(Tcharge)) {
        // we can probably end up here while resetting engine state - interpolation would fail
        warning(ObdCode::CUSTOM_ERR_TCHARGE_NOT_READY, "getTCharge NaN");
        return coolantTemp;
    }
 
    return Tcharge;
}
 
void initSpeedDensity() {
    veMap.initTable(config->veTable, config->veRpmBins, config->veLoadBins);
}