FGActuator.cpp

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

 Module:       FGActuator.cpp
 Author:       Jon Berndt
 Date started: 21 February 2006

 ------------- Copyright (C) 2007 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.

FUNCTIONAL DESCRIPTION
--------------------------------------------------------------------------------

HISTORY
--------------------------------------------------------------------------------

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

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

#include <stdlib.h>

#include "FGActuator.h"
#include "input_output/FGXMLElement.h"
#include "math/FGRealValue.h"
#include "models/FGFCS.h"

using namespace std;

namespace JSBSim {

IDENT(IdSrc,"$Id: FGActuator.cpp,v 1.38 2015/07/12 19:34:08 bcoconni Exp $");
IDENT(IdHdr,ID_ACTUATOR);

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


FGActuator::FGActuator(FGFCS* fcs, Element* element) : FGFCSComponent(fcs, element)
{
  // inputs are read from the base class constructor

  PreviousOutput = 0.0;
  PreviousHystOutput = 0.0;
  PreviousRateLimOutput = 0.0;
  PreviousLagInput = PreviousLagOutput = 0.0;
  bias = lag = hysteresis_width = deadband_width = 0.0;
  rate_limit_incr = rate_limit_decr = 0; // no limit
  fail_zero = fail_hardover = fail_stuck = false;
  ca = cb = 0.0;
  initialized = 0;
  saturated = false;

  if ( element->FindElement("deadband_width") ) {
    deadband_width = element->FindElementValueAsNumber("deadband_width");
  }
  if ( element->FindElement("hysteresis_width") ) {
    hysteresis_width = element->FindElementValueAsNumber("hysteresis_width");
  }

  // There can be a single rate limit specified, or increasing and 
  // decreasing rate limits specified, and rate limits can be numeric, or
  // a property.
  Element* ratelim_el = element->FindElement("rate_limit");
  while ( ratelim_el ) {
    FGParameter* rate_limit = 0;
    string rate_limit_str = ratelim_el->GetDataLine();

    trim(rate_limit_str);
    if (is_number(rate_limit_str))
      rate_limit = new FGRealValue(fabs(atof(rate_limit_str.c_str())));
    else {
      if (rate_limit_str[0] == '-') rate_limit_str.erase(0,1);
      FGPropertyNode* rate_limit_prop = PropertyManager->GetNode(rate_limit_str, true);
      if (!rate_limit_prop) {
        std::cerr << "No such property, " << rate_limit_str << " for rate limiting" << std::endl;
        ratelim_el = element->FindNextElement("rate_limit");
        continue;
      }
      rate_limit = new FGPropertyValue(rate_limit_prop);
    }

    if (ratelim_el->HasAttribute("sense")) {
      string sense = ratelim_el->GetAttributeValue("sense");
      if (sense.substr(0,4) == "incr")
        rate_limit_incr = rate_limit;
      else if (sense.substr(0,4) == "decr")
        rate_limit_decr = rate_limit;
    } else {
      rate_limit_incr = rate_limit;
      rate_limit_decr = rate_limit;
    }
    ratelim_el = element->FindNextElement("rate_limit");
  }

  if ( element->FindElement("bias") ) {
    bias = element->FindElementValueAsNumber("bias");
  }
  if ( element->FindElement("lag") ) {
    lag = element->FindElementValueAsNumber("lag");
    double denom = 2.00 + dt*lag;
    ca = dt*lag / denom;
    cb = (2.00 - dt*lag) / denom;
  }

  FGFCSComponent::bind();
  bind();

  Debug(0);
}

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

FGActuator::~FGActuator()
{
  delete rate_limit_incr;
  if (rate_limit_decr != rate_limit_incr)
    delete rate_limit_decr;

  Debug(1);
}

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

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

  PreviousOutput = PreviousHystOutput = PreviousRateLimOutput
    = PreviousLagInput = PreviousLagOutput = Output = 0.0; 
}

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

bool FGActuator::Run(void )
{
  Input = InputNodes[0]->getDoubleValue() * InputSigns[0];

  if( fcs->GetTrimStatus() ) initialized = 0;

  if (fail_zero) Input = 0;
  if (fail_hardover) Input =  clipmax*sign(Input);

  Output = Input; // Perfect actuator. At this point, if no failures are present
                  // and no subsequent lag, limiting, etc. is done, the output
                  // is simply the input. If any further processing is done
                  // (below) such as lag, rate limiting, hysteresis, etc., then
                  // the Input will be further processed and the eventual Output
                  // will be overwritten from this perfect value.

  if (fail_stuck) {
    Output = PreviousOutput;
  } else {
    if (lag != 0.0)              Lag();        // models actuator lag
    if (rate_limit_incr != 0 || rate_limit_decr != 0) RateLimit();  // limit the actuator rate
    if (deadband_width != 0.0)   Deadband();
    if (hysteresis_width != 0.0) Hysteresis();
    if (bias != 0.0)             Bias();       // models a finite bias
    if (delay != 0)              Delay();      // Model transport latency
  }

  PreviousOutput = Output; // previous value needed for "stuck" malfunction
  
  initialized = 1;

  Clip();

  if (clip) {
    saturated = false;
    if (Output >= clipmax && clipmax != 0) saturated = true;
    else if (Output <= clipmin && clipmin != 0) saturated = true;
  }

  if (IsOutput) SetOutput();

  return true;
}

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

void FGActuator::Bias(void)
{
  Output += bias;
}

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

void FGActuator::Lag(void)
{
  // "Output" on the right side of the "=" is the current frame input
  // for this Lag filter
  double input = Output;

  if ( initialized )
    Output = ca * (input + PreviousLagInput) + PreviousLagOutput * cb;

  PreviousLagInput = input;
  PreviousLagOutput = Output;
}

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

void FGActuator::Hysteresis(void)
{
  // Note: this function acts cumulatively on the "Output" parameter. So, "Output"
  // is - for the purposes of this Hysteresis method - really the input to the
  // method.
  double input = Output;
  
  if ( initialized ) {
    if (input > PreviousHystOutput)
      Output = max(PreviousHystOutput, input-0.5*hysteresis_width);
    else if (input < PreviousHystOutput)
      Output = min(PreviousHystOutput, input+0.5*hysteresis_width);
  }

  PreviousHystOutput = Output;
}

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

void FGActuator::RateLimit(void)
{
  // Note: this function acts cumulatively on the "Output" parameter. So, "Output"
  // is - for the purposes of this RateLimit method - really the input to the
  // method.
  double input = Output;
  if ( initialized ) {
    double delta = input - PreviousRateLimOutput;
    if (rate_limit_incr) {
      double rate_limit = rate_limit_incr->GetValue();
      if (delta > dt * rate_limit)
        Output = PreviousRateLimOutput + rate_limit * dt;
    }
    if (rate_limit_decr) {
      double rate_limit = -rate_limit_decr->GetValue();
      if (delta < dt * rate_limit)
        Output = PreviousRateLimOutput + rate_limit * dt;
    }
  }
  PreviousRateLimOutput = Output;
}

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

void FGActuator::Deadband(void)
{
  // Note: this function acts cumulatively on the "Output" parameter. So, "Output"
  // is - for the purposes of this Deadband method - really the input to the
  // method.
  double input = Output;

  if (input < -deadband_width/2.0) {
    Output = (input + deadband_width/2.0);
  } else if (input > deadband_width/2.0) {
    Output = (input - deadband_width/2.0);
  } else {
    Output = 0.0;
  }
}

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

void FGActuator::bind(void)
{
  string tmp = Name;
  if (Name.find("/") == string::npos) {
    tmp = "fcs/" + PropertyManager->mkPropertyName(Name, true);
  }
  const string tmp_zero = tmp + "/malfunction/fail_zero";
  const string tmp_hardover = tmp + "/malfunction/fail_hardover";
  const string tmp_stuck = tmp + "/malfunction/fail_stuck";
  const string tmp_sat = tmp + "/saturated";

  PropertyManager->Tie( tmp_zero, this, &FGActuator::GetFailZero, &FGActuator::SetFailZero);
  PropertyManager->Tie( tmp_hardover, this, &FGActuator::GetFailHardover, &FGActuator::SetFailHardover);
  PropertyManager->Tie( tmp_stuck, this, &FGActuator::GetFailStuck, &FGActuator::SetFailStuck);
  PropertyManager->Tie( tmp_sat, this, &FGActuator::IsSaturated);
}

//%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
//    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 FGActuator::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: -" << InputNames[0] << endl;
      else
        cout << "      INPUT: " << InputNames[0] << endl;

      if (IsOutput) {
        for (unsigned int i=0; i<OutputNodes.size(); i++)
          cout << "      OUTPUT: " << OutputNodes[i]->getName() << endl;
      }
      if (bias != 0.0) cout << "      Bias: " << bias << endl;
      if (rate_limit_incr != 0) {
        cout << "      Increasing rate limit: " << rate_limit_incr->GetName() << endl;
      }
      if (rate_limit_decr != 0) {
        cout << "      Decreasing rate limit: " << rate_limit_decr->GetName() << endl;
      }
      if (lag != 0) cout << "      Actuator lag: " << lag << endl;
      if (hysteresis_width != 0) cout << "      Hysteresis width: " << hysteresis_width << endl;
      if (deadband_width != 0) cout << "      Deadband width: " << deadband_width << endl;
    }
  }
  if (debug_lvl & 2 ) { // Instantiation/Destruction notification
    if (from == 0) cout << "Instantiated: FGActuator" << endl;
    if (from == 1) cout << "Destroyed:    FGActuator" << 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;
    }
  }
}
}