injector nonlinearity (#2916)

* nonlinear polynomial

* make existing tests work again

* test that nonlinearity is called

* s

* fix enum

* ui

* fix and test

* comment

* changeloggy

firmware/CHANGELOG.md

@@ -30,6 +30,9 @@ All notable user-facing or behavior-altering changes will be documented in this
 ### Breaking Changes
  - vvtOffset field migrated to four vvtOffsets fields. Anyone using VVT would need to manually adjust their configuration.  
 
+### Added
+ - Injector nonlinearity (small pulse) correction - so far just polynomial, but table modes coming soon.
+
 ## June 2021 Release "National Logistics Day"
 
 ### Fixed

firmware/controllers/algo/fuel/injector_model.cpp

@@ -104,14 +104,47 @@ float InjectorModelBase::getInjectionDuration(float fuelMassGram) const {
 	floatms_t baseDuration = fuelMassGram / m_massFlowRate * 1000;
 
 	if (baseDuration <= 0) {
-		// If 0 duration, don't add deadtime, just skip the injection.
+		// If 0 duration, don't correct or add deadtime, just skip the injection.
 		return 0.0f;
-	} else {
-		return baseDuration + m_deadtime;
 	}
+
+	// Correct short pulses (if enabled)
+	baseDuration = correctShortPulse(baseDuration);
+
+	return baseDuration + m_deadtime;
 }
 
 float InjectorModelBase::getFuelMassForDuration(floatms_t duration) const {
 	// Convert from ms -> grams
 	return duration * m_massFlowRate * 0.001f;
 }
+
+float InjectorModel::correctShortPulse(float baseDuration) const {
+	switch (CONFIG(injectorNonlinearMode)) {
+	case INJ_PolynomialAdder:
+		return correctInjectionPolynomial(baseDuration);
+	case INJ_None:
+	default:
+		return baseDuration;
+	}
+}
+
+float InjectorModel::correctInjectionPolynomial(float baseDuration) const {
+	if (baseDuration > CONFIG(applyNonlinearBelowPulse)) {
+		// Large pulse, skip correction.
+		return baseDuration;
+	}
+
+	auto& is = CONFIG(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;
+}

firmware/controllers/algo/fuel/injector_model.h

@@ -19,6 +19,7 @@ public:
 	virtual float getInjectorMassFlowRate() const = 0;
 	virtual float getInjectorFlowRatio() const = 0;
 	virtual expected<float> getAbsoluteRailPressure() const = 0;
+	virtual float correctShortPulse(float baseDuration) const = 0;
 
 	virtual void postState(float deadTime) const { (void)deadTime; };
 
@@ -36,4 +37,8 @@ public:
 	float getInjectorMassFlowRate() const override;
 	float getInjectorFlowRatio() const override;
 	expected<float> getAbsoluteRailPressure() const override;
+
+	// Small pulse correction logic
+	float correctShortPulse(float baseDuration) const override;
+	virtual float correctInjectionPolynomial(float baseDuration) const;
 };

firmware/controllers/algo/rusefi_enums.h

@@ -1059,3 +1059,8 @@ typedef enum __attribute__ ((__packed__)) {
 	ICM_FixedRailPressure = 1,
 	ICM_SensedRailPressure = 2,
 } injector_compensation_mode_e;
+
+typedef enum __attribute__ ((__packed__)) {
+	INJ_None = 0,
+	INJ_PolynomialAdder = 1,
+} InjectorNonlinearMode;

firmware/integration/rusefi_config.txt

@@ -1357,9 +1357,12 @@ tle8888_mode_e tle8888mode;
 	float unused2432;;"units", 1, 0, -20, 100, 0
 	float postCrankingFactor;+Fuel multiplier (enrichment) immediately after engine start;"mult", 1, 0, 1, 3, 2
 	float postCrankingDurationSec;+Time over which to taper out after start enrichment;"seconds", 1, 0, 0, 30, 0
-	ThermistorConf auxTempSensor1;todo: finish implementation #332
+	ThermistorConf auxTempSensor1
-	ThermistorConf auxTempSensor2;todo: finish implementation #332
+	ThermistorConf auxTempSensor2
-	uint8_t[6] unused2508;;"units", 1, 0, -20, 100, 0
+	uint16_t applyNonlinearBelowPulse;+Apply nonlinearity correction below a pulse of this duration. Pulses longer than this duration will receive no adjustment.;"ms", {1/1000}, 0, 0, 30, 3
+	custom InjectorNonlinearMode 1 bits, U08, @OFFSET@, [0:0], "None", "Polynomial"
+	InjectorNonlinearMode injectorNonlinearMode
+	uint8_t[3] unused2508;;"units", 1, 0, -20, 100, 0
 	int16_t etbFreq;;"Hz", 1, 0, 0, @@ETB_HW_MAX_FREQUENCY@@, 0
 	pid_s etbWastegatePid;
 	uint8_t[4] unused2536;;"units", 1, 0, -20, 100, 0
@@ -1395,7 +1398,8 @@ tle8888_mode_e tle8888mode;
 
 
 	pid_s[CAMS_PER_BANK iterate] auxPid;
-	uint8_t[40] unused1366;;"units", 1, 0, -20, 100, 0
+	float[8 iterate] injectorCorrectionPolynomial;;"", 1, 0, -1000, 1000, 4
+	uint8_t[8] unused1366;;"units", 1, 0, -20, 100, 0
 
 	linear_sensor_s oilPressure;
 

firmware/tunerstudio/rusefi.input

@@ -1403,7 +1403,8 @@ menuDialog = main
 		# basic
 		subMenu = injectorConfig,			"Injection configuration"
 		subMenu = injectionSettings,		"Injection hardware", 0, {isInjectionEnabled == 1}
-		subMenu = cylinderBankSelect,		"Cylinder bank selection"
+		subMenu = cylinderBankSelect,		"Cylinder bank selection", 0, {isInjectionEnabled == 1}
+		subMenu = injectorNonlinear,		"Injector small-pulse correction", 0, {isInjectionEnabled == 1}
 		subMenu = std_separator
 
 		# Air mass model
@@ -1940,6 +1941,21 @@ cmd_set_engine_type_default					= "@@TS_IO_TEST_COMMAND_char@@\x00\x31\x00\x00"
 		field = "Cylinder 11 ",						cylinderBankSelect11, {isInjectionEnabled == 1 && cylindersCount > 10}
 		field = "Cylinder 12 ",						cylinderBankSelect12, {isInjectionEnabled == 1 && cylindersCount > 11}
 
+	dialog = injectorNonlinearPolynomial, "Polynomial Adder", yAxis
+		field = "Add nonlinearity below pulse",		applyNonlinearBelowPulse
+		field = "constant",							injectorCorrectionPolynomial1
+		field = "x^1",								injectorCorrectionPolynomial2
+		field = "x^2",								injectorCorrectionPolynomial3
+		field = "x^3",								injectorCorrectionPolynomial4
+		field = "x^4",								injectorCorrectionPolynomial5
+		field = "x^5",								injectorCorrectionPolynomial6
+		field = "x^6",								injectorCorrectionPolynomial7
+		field = "x^7",								injectorCorrectionPolynomial8
+
+	dialog = injectorNonlinear
+		field = "Small pulse correction mode",		injectorNonlinearMode
+		panel = injectorNonlinearPolynomial, {1}, { injectorNonlinearMode != 0 }
+
 	dialog = testFsio, "FSIO Test"
 		commandButton = "FSIO#1",	cmd_test_fsio1
 		commandButton = "FSIO#2",	cmd_test_fsio2

unit_tests/tests/ignition_injection/test_injector_model.cpp

@@ -5,6 +5,7 @@
 
 #include "gtest/gtest.h"
 
+using ::testing::_;
 using ::testing::StrictMock;
 
 class MockInjectorModel : public InjectorModelBase {
@@ -13,6 +14,7 @@ public:
 	MOCK_METHOD(float, getInjectorMassFlowRate, (), (const, override));
 	MOCK_METHOD(float, getInjectorFlowRatio, (), (const, override));
 	MOCK_METHOD(expected<float>, getAbsoluteRailPressure, (), (const, override));
+	MOCK_METHOD(float, correctShortPulse, (float baseDuration), (const, override));
 };
 
 TEST(InjectorModel, Prepare) {
@@ -28,9 +30,12 @@ TEST(InjectorModel, getInjectionDuration) {
 	StrictMock<MockInjectorModel> dut;
 
 	EXPECT_CALL(dut, getDeadtime())
-		.WillRepeatedly(Return(2.0f));
+		.WillOnce(Return(2.0f));
 	EXPECT_CALL(dut, getInjectorMassFlowRate())
-		.WillRepeatedly(Return(4.8f)); // 400cc/min
+		.WillOnce(Return(4.8f)); // 400cc/min
+	EXPECT_CALL(dut, correctShortPulse(_))
+		.Times(2)
+		.WillRepeatedly([](float b) { return b; });
 
 	dut.prepare();
 
@@ -38,6 +43,46 @@ TEST(InjectorModel, getInjectionDuration) {
 	EXPECT_NEAR(dut.getInjectionDuration(0.02f), 20 / 4.8f + 2.0f, EPS4D);
 }
 
+TEST(InjectorModel, getInjectionDurationNonlinear) {
+	StrictMock<MockInjectorModel> dut;
+
+	EXPECT_CALL(dut, getDeadtime())
+		.WillOnce(Return(2.0f));
+	EXPECT_CALL(dut, getInjectorMassFlowRate())
+		.WillOnce(Return(4.8f)); // 400cc/min
+
+	// Dummy nonlinearity correction: just doubles the pulse
+	EXPECT_CALL(dut, correctShortPulse(_))
+		.Times(2)
+		.WillRepeatedly([](float b) { return 2 * b; });
+
+	dut.prepare();
+
+	EXPECT_NEAR(dut.getInjectionDuration(0.01f), 2 * 10 / 4.8f + 2.0f, EPS4D);
+	EXPECT_NEAR(dut.getInjectionDuration(0.02f), 2 * 20 / 4.8f + 2.0f, EPS4D);
+}
+
+TEST(InjectorModel, nonlinearPolynomial) {
+	WITH_ENGINE_TEST_HELPER(TEST_ENGINE);
+	InjectorModel dut;
+	INJECT_ENGINE_REFERENCE(&dut);
+
+	CONFIG(applyNonlinearBelowPulse) = 10;
+
+	for (int i = 0; i < 8; i++) {
+		CONFIG(injectorCorrectionPolynomial)[i] = i + 1;
+	}
+
+	// expect return of the original value, plus polynomial f(x)
+	EXPECT_NEAR(dut.correctInjectionPolynomial(-3), -3 + -13532, EPS4D);
+	EXPECT_NEAR(dut.correctInjectionPolynomial(-2), -2 +   -711, EPS4D);
+	EXPECT_NEAR(dut.correctInjectionPolynomial(-1), -1 +     -4, EPS4D);
+	EXPECT_NEAR(dut.correctInjectionPolynomial(0),   0 +      1, EPS4D);
+	EXPECT_NEAR(dut.correctInjectionPolynomial(1),   1 +     36, EPS4D);
+	EXPECT_NEAR(dut.correctInjectionPolynomial(2),   2 +   1793, EPS4D);
+	EXPECT_NEAR(dut.correctInjectionPolynomial(3),   3 +  24604, EPS4D);
+}
+
 TEST(InjectorModel, Deadtime) {
 	WITH_ENGINE_TEST_HELPER(TEST_ENGINE);