Closed Loop Idle Ignition Timing small improvements (#5635)

* After-start enrichment handling more similar to OEM and other Standalone EFI systems

* Corrections and tidying-up

* Corrected small mistake in TunerStudio definition

* Compatibility fixes

* Readability fix

* Changed to more appropriate cycles instead of seconds, bugfix for TS

* Typo fix...

* Idle Ignition Timing improvements

* Uninitialized variable for Unit Tests?

* Zero value should disable new feature

---------

Co-authored-by: pchmura4 <>

firmware/CHANGELOG.md

@@ -35,6 +35,8 @@ Release template (copy/paste this for new release):
 ### Added
  - DAC with Lua #5601
  - TunerStudio cacerts fix script #5536 
+ - Idle Timing Control - Soft Entry mechanism, in case of aggresive PID tuning this can help when engine enters close loop idle
+ - Idle Timing Control - I factor configurable now
 
 ### Fixed
  - Changing idle stepper settings causes kernel panic

firmware/controllers/actuators/idle_thread.cpp

@@ -187,8 +187,19 @@ float IdleController::getIdleTimingAdjustment(int rpm, int targetRpm, Phase phas
 	if (phase != Phase::Idling) {
 		m_timingPid.reset();
 		return 0;
+	} else {
+		// If we are entering idle, and the PID settings are aggressive, it's good to make a soft entry upon entering closed loop
+		if (m_lastPhase == Phase::CrankToIdleTaper) {
+			m_crankTaperEndTime = engine->fuelComputer.running.timeSinceCrankingInSecs;
+			m_idleTimingSoftEntryEndTime = m_crankTaperEndTime + engineConfiguration->idleTimingSoftEntryTime;
+		}
+		if (engineConfiguration->idleTimingSoftEntryTime > 0.0f) {
+			// Use interpolation for correction taper
+			m_timingPid.setErrorAmplification(interpolateClamped(m_crankTaperEndTime, 0.0f, m_idleTimingSoftEntryEndTime, 1.0f, engine->fuelComputer.running.timeSinceCrankingInSecs));
+		}
 	}
 
+
 	// We're now in the idle mode, and RPM is inside the Timing-PID regulator work zone!
 	return m_timingPid.getOutput(targetRpm, rpm, FAST_CALLBACK_PERIOD_MS / 1000.0f);
 }

firmware/controllers/actuators/idle_thread.h

@@ -95,6 +95,9 @@ private:
 	efitimeus_t restoreAfterPidResetTimeUs = 0;
 	// used by 'dashpot' (hold+decay) logic for iacByTpsTaper
 	efitimeus_t lastTimeRunningUs = 0;
+	// used by "soft" idle entry
+	float m_crankTaperEndTime = 0.0f;
+	float m_idleTimingSoftEntryEndTime = 0.0f;
 
 	// This is stored by getClosedLoop and used in case we want to "do nothing"
 	float m_lastAutomaticPosition = 0;

firmware/integration/rusefi_config.txt

@@ -1355,6 +1355,7 @@ tChargeMode_e tChargeMode;
 	int16_t etb_iTermMax;iTerm max value;"", 1, 0, -30000, 30000, 0
 
 	pid_s idleTimingPid;See useIdleTimingPidControl
+	float idleTimingSoftEntryTime
 
 	int16_t etbRocExpAverageLength;By the way ETB PID runs at 500hz, length in 1/500 of second here.
 

firmware/tunerstudio/rusefi.input

@@ -3465,11 +3465,14 @@ cmd_set_engine_type_default					= "@@TS_IO_TEST_COMMAND_char@@@@ts_command_e_TS_
 		field = "#Gain is in degrees advance per rpm away from target"
 		field = "#A good starting point is 0.1 = 10 deg per 100 rpm"
 		field = "Proportional gain",									idleTimingPid_pFactor, {useIdleTimingPidControl == 1}
+		field = "Integral gain",									idleTimingPid_iFactor, {useIdleTimingPidControl == 1}
 		field = "Derivative gain",									idleTimingPid_dFactor, {useIdleTimingPidControl == 1}
 		field = ""
 		field = "Min adjustment (retard)",								idleTimingPid_minValue, {useIdleTimingPidControl == 1}
 		field = "Max adjustment (advance)",								idleTimingPid_maxValue, {useIdleTimingPidControl == 1}
 		field = ""
+		field = "Soft entry time",								idleTimingSoftEntryTime, {useIdleTimingPidControl == 1}
+		field = ""
 		field = "#Use debug mode 'Timing' to view idle timing adjustment"
 
 ;			Engine->Fan Settings

unit_tests/tests/test_idle_controller.cpp

@@ -26,6 +26,7 @@ TEST(idle_v2, timingPid) {
 	engineConfiguration->idleTimingPid.pFactor = 0.1;
 	engineConfiguration->idleTimingPid.minValue = -10;
 	engineConfiguration->idleTimingPid.maxValue = 10;
+	engineConfiguration->idleTimingSoftEntryTime = 0.0f;
 	dut.init();
 
 	// Check that out of idle mode it doesn't do anything