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Refactor PID inner core out

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Ben V. Brown
2021-09-12 20:44:09 +10:00
parent c99d6b731e
commit 416af2ff70
1 changed files with 38 additions and 39 deletions
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77
source/Core/Threads/PIDThread.cpp
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@@ -21,8 +21,9 @@ uint32_t currentTempTargetDegC = 0; // Current temperature target in
int32_t powerSupplyWattageLimit = 0;
bool heaterThermalRunaway = false;
static void detectThermalRunaway(const int16_t currentTipTempInC, const int tError);
static void setOutputx10WattsViaFilters(int32_t x10Watts);
static int32_t getPIDResultX10Watts(int32_t tError);
static void detectThermalRunaway(const int16_t currentTipTempInC, const int tError);
static void setOutputx10WattsViaFilters(int32_t x10Watts);
/* StartPIDTask function */
void startPIDTask(void const *argument __unused) {
@@ -32,9 +33,8 @@ void startPIDTask(void const *argument __unused) {
*/
setTipX10Watts(0); // disable the output at startup
history<int32_t, PID_TIM_HZ> tempError = {{0}, 0, 0};
currentTempTargetDegC = 0; // Force start with no output (off). If in sleep / soldering this will
// be over-ridden rapidly
currentTempTargetDegC = 0; // Force start with no output (off). If in sleep / soldering this will
// be over-ridden rapidly
pidTaskNotification = xTaskGetCurrentTaskHandle();
uint32_t PIDTempTarget = 0;
// Pre-seed the adc filters
@@ -42,12 +42,12 @@ void startPIDTask(void const *argument __unused) {
vTaskDelay(2);
TipThermoModel::getTipInC(true);
}
int32_t x10WattsOut = 0;
for (;;) {
x10WattsOut = 0;
// This is a call to block this thread until the ADC does its samples
if (ulTaskNotifyTake(pdTRUE, 2000)) {
int32_t x10WattsOut = 0;
// Do the reading here to keep the temp calculations churning along
uint32_t currentTipTempInC = TipThermoModel::getTipInC(true);
PIDTempTarget = currentTempTargetDegC;
@@ -61,43 +61,12 @@ void startPIDTask(void const *argument __unused) {
if (PIDTempTarget > TipThermoModel::getTipMaxInC()) {
PIDTempTarget = TipThermoModel::getTipMaxInC();
}
// As we get close to our target, temp noise causes the system
// to be unstable. Use a rolling average to dampen it.
// We overshoot by roughly 1 degree C.
// This helps stabilize the display.
int32_t tError = PIDTempTarget - currentTipTempInC;
tError = tError > INT16_MAX ? INT16_MAX : tError;
tError = tError < INT16_MIN ? INT16_MIN : tError;
tempError.update(tError);
// Now for the PID!
// P term - total power needed to hit target temp next cycle.
// thermal mass = 1690 milliJ/*C for my tip.
// = Watts*Seconds to raise Temp from room temp to +100*C, divided by 100*C.
// we divide milliWattsNeeded by 20 to let the I term dominate near the set point.
// This is necessary because of the temp noise and thermal lag in the system.
// Once we have feed-forward temp estimation we should be able to better tune this.
int32_t x10WattsNeeded = tempToX10Watts(tError);
// note that milliWattsNeeded is sometimes negative, this counters overshoot
// from I term's inertia.
x10WattsOut += x10WattsNeeded;
// I term - energy needed to compensate for heat loss.
// We track energy put into the system over some window.
// Assuming the temp is stable, energy in = energy transfered.
// (If it isn't, P will dominate).
x10WattsOut += x10WattHistory.average();
// D term - use sudden temp change to counter fast cooling/heating.
// In practice, this provides an early boost if temp is dropping
// and counters extra power if the iron is no longer losing temp.
// basically: temp - lastTemp
// Unfortunately, our temp signal is too noisy to really help.
detectThermalRunaway(currentTipTempInC, tError);
x10WattsOut = getPIDResultX10Watts(tError);
} else {
detectThermalRunaway(currentTipTempInC, 0);
}
@@ -109,6 +78,36 @@ void startPIDTask(void const *argument __unused) {
}
}
int32_t getPIDResultX10Watts(int32_t tError) {
// Now for the PID!
// P term - total power needed to hit target temp next cycle.
// thermal mass = 1690 milliJ/*C for my tip.
// = Watts*Seconds to raise Temp from room temp to +100*C, divided by 100*C.
// we divide milliWattsNeeded by 20 to let the I term dominate near the set point.
// This is necessary because of the temp noise and thermal lag in the system.
// Once we have feed-forward temp estimation we should be able to better tune this.
int32_t x10WattsNeeded = tempToX10Watts(tError);
// note that milliWattsNeeded is sometimes negative, this counters overshoot
// from I term's inertia.
int32_t x10WattsOut = x10WattsNeeded;
// I term - energy needed to compensate for heat loss.
// We track energy put into the system over some window.
// Assuming the temp is stable, energy in = energy transfered.
// (If it isn't, P will dominate).
x10WattsOut += x10WattHistory.average();
// D term - use sudden temp change to counter fast cooling/heating.
// In practice, this provides an early boost if temp is dropping
// and counters extra power if the iron is no longer losing temp.
// basically: temp - lastTemp
// Unfortunately, our temp signal is too noisy to really help.
return x10WattsOut;
}
void detectThermalRunaway(const int16_t currentTipTempInC, const int tError) {
static uint16_t tipTempCRunawayTemp = 0;
static TickType_t runawaylastChangeTime = 0;