FGPID.cpp

/*%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

 Module:       FGPID.cpp
 Author:       Jon S. Berndt
 Date started: 6/17/2006

 ------------- Copyright (C) 2006 Jon S. Berndt (jon@jsbsim.org) -------------

 This program is free software; you can redistribute it and/or modify it under
 the terms of the GNU Lesser General Public License as published by the Free Software
 Foundation; either version 2 of the License, or (at your option) any later
 version.

 This program is distributed in the hope that it will be useful, but WITHOUT
 ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
 FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public License for more
 details.

 You should have received a copy of the GNU Lesser General Public License along with
 this program; if not, write to the Free Software Foundation, Inc., 59 Temple
 Place - Suite 330, Boston, MA  02111-1307, USA.

 Further information about the GNU Lesser General Public License can also be found on
 the world wide web at http://www.gnu.org.

HISTORY
--------------------------------------------------------------------------------
Initial code 6/17/2006 JSB

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
COMMENTS, REFERENCES,  and NOTES
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
INCLUDES
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%*/

#include "FGPID.h"
#include "input_output/FGXMLElement.h"
#include <string>
#include <iostream>

using namespace std;

namespace JSBSim {

IDENT(IdSrc,"$Id: FGPID.cpp,v 1.24 2014/01/13 10:46:09 ehofman Exp $");
IDENT(IdHdr,ID_PID);

/*%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
CLASS IMPLEMENTATION
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%*/

FGPID::FGPID(FGFCS* fcs, Element* element) : FGFCSComponent(fcs, element)
{
  string kp_string, ki_string, kd_string;

  Kp = Ki = Kd = 0.0;
  KpPropertyNode = 0;
  KiPropertyNode = 0;
  KdPropertyNode = 0;
  KpPropertySign = 1.0;
  KiPropertySign = 1.0;
  KdPropertySign = 1.0;
  I_out_total = 0.0;
  Input_prev = Input_prev2 = 0.0;
  Trigger = 0;
  ProcessVariableDot = 0;
  IsStandard = false;
  IntType = eNone;       // No integrator initially defined.

  string pid_type = element->GetAttributeValue("type");

  if (pid_type == "standard") IsStandard = true;

  if ( element->FindElement("kp") ) {
    kp_string = element->FindElementValue("kp");
    if (!is_number(kp_string)) { // property
      if (kp_string[0] == '-') {
       KpPropertySign = -1.0;
       kp_string.erase(0,1);
      }
      KpPropertyNode = PropertyManager->GetNode(kp_string);
    } else {
      Kp = element->FindElementValueAsNumber("kp");
    }
  }

  if ( element->FindElement("ki") ) {
    ki_string = element->FindElementValue("ki");

    string integ_type = element->FindElement("ki")->GetAttributeValue("type");
    if (integ_type == "rect") {            // Use rectangular integration
      IntType = eRectEuler;
    } else if (integ_type == "trap") {     // Use trapezoidal integration
      IntType = eTrapezoidal;
    } else if (integ_type == "ab2") {      // Use Adams Bashforth 2nd order integration
      IntType = eAdamsBashforth2;
    } else if (integ_type == "ab3") {      // Use Adams Bashforth 3rd order integration
      IntType = eAdamsBashforth3;
    } else {                               // Use default Adams Bashforth 2nd order integration
      IntType = eAdamsBashforth2;
    }

    if (!is_number(ki_string)) { // property
      if (ki_string[0] == '-') {
       KiPropertySign = -1.0;
       ki_string.erase(0,1);
      }
      KiPropertyNode = PropertyManager->GetNode(ki_string);
    } else {
      Ki = element->FindElementValueAsNumber("ki");
    }
  }

  if ( element->FindElement("kd") ) {
    kd_string = element->FindElementValue("kd");
    if (!is_number(kd_string)) { // property
      if (kd_string[0] == '-') {
       KdPropertySign = -1.0;
       kd_string.erase(0,1);
      }
      KdPropertyNode = PropertyManager->GetNode(kd_string);
    } else {
      Kd = element->FindElementValueAsNumber("kd");
    }
  }

  if (element->FindElement("pvdot")) {
    ProcessVariableDot =  PropertyManager->GetNode(element->FindElementValue("pvdot"));
  }

  if (element->FindElement("trigger")) {
    Trigger =  PropertyManager->GetNode(element->FindElementValue("trigger"));
  }

  FGFCSComponent::bind();
  string tmp;
  if (Name.find("/") == string::npos) {
    tmp = "fcs/" + PropertyManager->mkPropertyName(Name, true);
  } else {
    tmp = Name;
  }
  typedef double (FGPID::*PMF)(void) const;
  PropertyManager->Tie(tmp+"/initial-integrator-value", this, (PMF)0, &FGPID::SetInitialOutput);

  Debug(0);
}

//%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

FGPID::~FGPID()
{
  Debug(1);
}

//%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

void FGPID::ResetPastStates(void)
{
  FGFCSComponent::ResetPastStates();

  Input_prev = Input_prev2 = Output = I_out_total = 0.0;
}

//%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

bool FGPID::Run(void )
{
  double I_out_delta = 0.0;
  double Dval = 0;

  Input = InputNodes[0]->getDoubleValue() * InputSigns[0];

  if (KpPropertyNode != 0) Kp = KpPropertyNode->getDoubleValue() * KpPropertySign;
  if (KiPropertyNode != 0) Ki = KiPropertyNode->getDoubleValue() * KiPropertySign;
  if (KdPropertyNode != 0) Kd = KdPropertyNode->getDoubleValue() * KdPropertySign;

  if (ProcessVariableDot) {
    Dval = ProcessVariableDot->getDoubleValue();
  } else {
    Dval = (Input - Input_prev)/dt;
  }

  // Do not continue to integrate the input to the integrator if a wind-up
  // condition is sensed - that is, if the property pointed to by the trigger
  // element is non-zero. Reset the integrator to 0.0 if the Trigger value
  // is negative.

  double test = 0.0;
  if (Trigger != 0) test = Trigger->getDoubleValue();

  if (fabs(test) < 0.000001) {
    switch(IntType) {
    case eRectEuler:
      I_out_delta = Ki * dt * Input;                         // Normal rectangular integrator
      break;
    case eTrapezoidal:
      I_out_delta = (Ki/2.0) * dt * (Input + Input_prev);    // Trapezoidal integrator
      break;
    case eAdamsBashforth2:
      I_out_delta = Ki * dt * (1.5*Input - 0.5*Input_prev);  // 2nd order Adams Bashforth integrator
      break;
    case eAdamsBashforth3:                                   // 3rd order Adams Bashforth integrator
      I_out_delta = (Ki/12.0) * dt * (23.0*Input - 16.0*Input_prev + 5.0*Input_prev2);
      break;
    case eNone:
      // No integator is defined or used.
      I_out_delta = 0.0;
      break;
    }
  }

  if (test < 0.0) I_out_total = 0.0;  // Reset integrator to 0.0
  
  I_out_total += I_out_delta;

  if (IsStandard) {
    Output = Kp * (Input + I_out_total + Kd*Dval);
  } else {
    Output = Kp*Input + I_out_total + Kd*Dval;
  }

  Input_prev = Input;
  Input_prev2 = Input_prev;

  Clip();
  if (IsOutput) SetOutput();

  return true;
}

//%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
//    The bitmasked value choices are as follows:
//    unset: In this case (the default) JSBSim would only print
//       out the normally expected messages, essentially echoing
//       the config files as they are read. If the environment
//       variable is not set, debug_lvl is set to 1 internally
//    0: This requests JSBSim not to output any messages
//       whatsoever.
//    1: This value explicity requests the normal JSBSim
//       startup messages
//    2: This value asks for a message to be printed out when
//       a class is instantiated
//    4: When this value is set, a message is displayed when a
//       FGModel object executes its Run() method
//    8: When this value is set, various runtime state variables
//       are printed out periodically
//    16: When set various parameters are sanity checked and
//       a message is printed out when they go out of bounds

void FGPID::Debug(int from)
{
  if (debug_lvl <= 0) return;

  if (debug_lvl & 1) { // Standard console startup message output
    if (from == 0) { // Constructor
      if (InputSigns[0] < 0)
        cout << "      INPUT: -" << InputNodes[0]->GetName() << endl;
      else
        cout << "      INPUT: " << InputNodes[0]->GetName() << endl;

      if (IsOutput) {
        for (unsigned int i=0; i<OutputNodes.size(); i++)
          cout << "      OUTPUT: " << OutputNodes[i]->getName() << endl;
      }
    }
  }
  if (debug_lvl & 2 ) { // Instantiation/Destruction notification
    if (from == 0) cout << "Instantiated: FGPID" << endl;
    if (from == 1) cout << "Destroyed:    FGPID" << endl;
  }
  if (debug_lvl & 4 ) { // Run() method entry print for FGModel-derived objects
  }
  if (debug_lvl & 8 ) { // Runtime state variables
  }
  if (debug_lvl & 16) { // Sanity checking
  }
  if (debug_lvl & 64) {
    if (from == 0) { // Constructor
      cout << IdSrc << endl;
      cout << IdHdr << endl;
    }
  }
}
}