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/*
* FOPDT.cpp
*
* Created on: 16 Aug 2016
* Author: David
*/
#include "FOPDT.h"
#if HAS_MASS_STORAGE
# include "Storage/FileStore.h"
#endif
#if SUPPORT_CAN_EXPANSION
# include <CanMessageFormats.h>
#endif
#if SUPPORT_OBJECT_MODEL
// Object model table and functions
// Note: if using GCC version 7.3.1 20180622 and lambda functions are used in this table, you must compile this file with option -std=gnu++17.
// Otherwise the table will be allocated in RAM instead of flash, which wastes too much RAM.
// Macro to build a standard lambda function that includes the necessary type conversions
#define OBJECT_MODEL_FUNC(...) OBJECT_MODEL_FUNC_BODY(FopDt, __VA_ARGS__)
#define OBJECT_MODEL_FUNC_IF(...) OBJECT_MODEL_FUNC_IF_BODY(FopDt, __VA_ARGS__)
constexpr ObjectModelTableEntry FopDt::objectModelTable[] =
{
// Within each group, these entries must be in alphabetical order
// 0. FopDt members
{ "deadTime", OBJECT_MODEL_FUNC(self->deadTime, 1), ObjectModelEntryFlags::none },
{ "enabled", OBJECT_MODEL_FUNC(self->enabled), ObjectModelEntryFlags::none },
{ "gain", OBJECT_MODEL_FUNC(self->GetGainFanOff(), 1), ObjectModelEntryFlags::none }, // legacy, to be removed
{ "heatingRate", OBJECT_MODEL_FUNC(self->heatingRate, 3), ObjectModelEntryFlags::none },
{ "inverted", OBJECT_MODEL_FUNC(self->inverted), ObjectModelEntryFlags::none },
{ "maxPwm", OBJECT_MODEL_FUNC(self->maxPwm, 2), ObjectModelEntryFlags::none },
{ "pid", OBJECT_MODEL_FUNC(self, 1), ObjectModelEntryFlags::none },
{ "standardVoltage", OBJECT_MODEL_FUNC(self->standardVoltage, 1), ObjectModelEntryFlags::none },
{ "timeConstant", OBJECT_MODEL_FUNC(self->GetTimeConstantFanOff(), 1), ObjectModelEntryFlags::none },
{ "timeConstantFansOn", OBJECT_MODEL_FUNC(self->GetTimeConstantFanOn(), 1), ObjectModelEntryFlags::none },
// 1. PID members
{ "d", OBJECT_MODEL_FUNC(self->loadChangeParams.tD * self->loadChangeParams.kP, 1), ObjectModelEntryFlags::none },
{ "i", OBJECT_MODEL_FUNC(self->loadChangeParams.recipTi * self->loadChangeParams.kP, 1), ObjectModelEntryFlags::none },
{ "overridden", OBJECT_MODEL_FUNC(self->pidParametersOverridden), ObjectModelEntryFlags::none },
{ "p", OBJECT_MODEL_FUNC(self->loadChangeParams.kP, 1), ObjectModelEntryFlags::none },
{ "used", OBJECT_MODEL_FUNC(self->usePid), ObjectModelEntryFlags::none },
};
constexpr uint8_t FopDt::objectModelTableDescriptor[] = { 2, 10, 5 };
DEFINE_GET_OBJECT_MODEL_TABLE(FopDt)
#endif
// The heater model is disabled until the user declares the heater to be a bed, chamber or tool heater
FopDt::FopDt() noexcept
{
Clear();
}
// Check the model parameters are sensible, if they are then save them and return true.
bool FopDt::SetParameters(float phr, float pcrFanOff, float pcrFanOn, float pdt, float pMaxPwm, float temperatureLimit, float pVoltage, bool pUsePid, bool pInverted) noexcept
{
// DC 2017-06-20: allow S down to 0.01 for one of our OEMs (use > 0.0099 because >= 0.01 doesn't work due to rounding error)
const float maxTempIncrease = max<float>(1500.0, temperatureLimit + 500.0);
if ( phr/pcrFanOff > 10.0 // minimum 10C temperature rise (same as with earlier heater model)
&& phr/pcrFanOff <= maxTempIncrease // max temperature increase within limits
&& pcrFanOn >= pcrFanOff
&& pdt > 0.099
&& 0.5 >= pdt * pcrFanOn // dead time less then cooling time constant
&& pMaxPwm > 0.0099
&& pMaxPwm <= 1.0
)
{
heatingRate = phr;
coolingRateFanOff = pcrFanOff;
coolingRateChangeFanOn = pcrFanOn - pcrFanOff;
deadTime = pdt;
maxPwm = pMaxPwm;
standardVoltage = pVoltage;
usePid = pUsePid;
inverted = pInverted;
enabled = true;
CalcPidConstants();
return true;
}
return false;
}
void FopDt::Clear() noexcept
{
SetDefaultToolParameters(); // set some values so that we don't report rubbish in the OM
enabled = false; // heater is disabled until the parameters are set
}
// Set up default parameters for a tool heater and enable the model
void FopDt::SetDefaultToolParameters() noexcept
{
heatingRate = DefaultHotEndHeaterHeatingRate;
coolingRateFanOff = DefaultHotEndHeaterCoolingRate;
deadTime = DefaultHotEndHeaterDeadTime;
coolingRateChangeFanOn = 0.0;
maxPwm = 1.0;
standardVoltage = 0.0;
usePid = true;
inverted = false;
enabled = true;
CalcPidConstants();
}
// Set up default parameters for a bed/chamber heater and enable the model
void FopDt::SetDefaultBedOrChamberParameters() noexcept
{
heatingRate = DefaultBedHeaterHeatingRate;
coolingRateFanOff = DefaultBedHeaterCoolingRate;
deadTime = DefaultBedHeaterDeadTime;
coolingRateChangeFanOn = 0.0;
maxPwm = 1.0;
standardVoltage = 0.0;
usePid = false;
inverted = false;
enabled = true;
CalcPidConstants();
}
// Get the PID parameters as reported by M301
M301PidParameters FopDt::GetM301PidParameters(bool forLoadChange) const noexcept
{
M301PidParameters rslt;
const PidParameters& pp = GetPidParameters(forLoadChange);
const float reportedKp = pp.kP * 255.0;
rslt.kP = reportedKp;
rslt.kI = pp.recipTi * reportedKp;
rslt.kD = pp.tD * reportedKp;
return rslt;
}
// Override the PID parameters. We set both sets to the same parameters.
void FopDt::SetM301PidParameters(const M301PidParameters& pp) noexcept
{
loadChangeParams.kP = setpointChangeParams.kP = pp.kP * (1.0/255.0);
loadChangeParams.recipTi = setpointChangeParams.recipTi = pp.kI/pp.kP;
loadChangeParams.tD = setpointChangeParams.tD = pp.kD/pp.kP;
pidParametersOverridden = true;
}
#if HAS_MASS_STORAGE
// Write the model parameters to file returning true if no error
bool FopDt::WriteParameters(FileStore *f, size_t heater) const noexcept
{
String<StringLength256> scratchString;
scratchString.printf("M307 H%u R%.3f C%.3f:%.3f D%.2f S%.2f V%.1f B%d I%d\n",
heater,
(double)heatingRate,
(double)GetTimeConstantFanOff(),
(double)GetTimeConstantFanOn(),
(double)deadTime,
(double)maxPwm,
(double)standardVoltage,
(usePid) ? 0 : 1,
(inverted) ? 1 : 0);
bool ok = f->Write(scratchString.c_str());
if (ok && pidParametersOverridden)
{
const M301PidParameters pp = GetM301PidParameters(false);
scratchString.printf("M301 H%u P%.1f I%.3f D%.1f\n", heater, (double)pp.kP, (double)pp.kI, (double)pp.kD);
ok = f->Write(scratchString.c_str());
}
return ok;
}
#endif
/* Re-calculate the PID parameters.
* For some possible formulas, see "Comparison of some well-known PID tuning formulas", Computers and Chemical Engineering 30 (2006) 1416�1423,
* available at http://www.ece.ualberta.ca/~marquez/journal_publications_files/papers/tan_cce_06.pdf
* Here are some examples, where r = td/tc:
* Cohen-Coon (modified to use half the original Kc value):
* Kc = (0.67/G) * (r + 0.185)
* Ti = 2.5 * td * (tc + 0.185 * td)/(tc + 0.611 * td)
* Td = 0.37 * td * tc/(tc + 0.185 * td)
* Ho et al, best response to setpoint changes:
* Kc = (1.086/G) * (r^-0.869
* Ti = tc/(0.74 - 0.13 * r)
* Td = 0.348 * tc * r^0.914
* IAE-setpoint:
* Kc = (0.65/G) * r^-1.04432
* Ti = tc/(0.9895 + 0.09539 * r)
* Td = 0.50814 * tc * r^1.08433
* Ho et al, best response to load changes:
* Kc = (1.435/G) * r^-0.921
* Ti = 1.14 * tc * r^0.749
* Td = 0.482 * tc * r^1.137
* ITAE-load:
* Kc = (0.77902/G) * r^-1.06401
* Ti = (tc/1.14311) * r^0.70949
* Td = 0.57137 * tc * r^1.03826
* However, none of these works well in this application. The setpoint-based methods have integral times comparable to the process time
* constant. This makes them very slow to reach that target temperature. Typically, the power is reduced too soon, so the temperature
* flattens out too soon it and then it takes a very long time for the integral term to accumulate to the required value. The load-based
* ones tend to have massive overshoot when the setpoint is changed, and even in the steady state some of them have marginal stability.
*/
void FopDt::CalcPidConstants() noexcept
{
const float averageCoolingRate = coolingRateFanOff + 0.5 * coolingRateChangeFanOn;
loadChangeParams.kP = 0.7/(heatingRate * deadTime);
loadChangeParams.recipTi = powf(averageCoolingRate, 0.25)/(1.14 * powf(deadTime, 0.75)); // Ti = 1.14 * timeConstant^0.25 * deadTime^0.75 (Ho et al)
loadChangeParams.tD = deadTime * 0.7;
setpointChangeParams.kP = 0.7/(heatingRate * deadTime);
setpointChangeParams.recipTi = powf(coolingRateFanOff, 0.5)/powf(deadTime, 0.5); // Ti = timeConstant^0.5 * deadTime^0.5
setpointChangeParams.tD = deadTime * 0.7;
pidParametersOverridden = false;
}
#if SUPPORT_CAN_EXPANSION
void FopDt::SetupCanMessage(unsigned int heater, CanMessageUpdateHeaterModelNew& msg) const noexcept
{
msg.heater = heater;
msg.heatingRate = heatingRate;
msg.coolingRate = coolingRateFanOff;
msg.coolingRateChangeFanOn = coolingRateChangeFanOn;
msg.coolingRateChangeExtruding = 0.0;
msg.zero2 = 0.0;
msg.deadTime = deadTime;
msg.maxPwm = maxPwm;
msg.standardVoltage = standardVoltage;
msg.enabled = enabled;
msg.usePid = usePid;
msg.inverted = inverted;
msg.pidParametersOverridden = pidParametersOverridden;
msg.kP = setpointChangeParams.kP;
msg.recipTi = setpointChangeParams.recipTi;
msg.tD = setpointChangeParams.tD;
}
#endif
// End
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