470a551176
This reverts commit 91ae41f9ef.
We do not need this as outputs already are written to the property
tree and most intermediate values can easily be calculated
manually.
249 lines
7 KiB
C++
249 lines
7 KiB
C++
// pidcontroller.cxx - implementation of PID controller
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//
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// Written by Torsten Dreyer
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// Based heavily on work created by Curtis Olson, started January 2004.
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//
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// Copyright (C) 2004 Curtis L. Olson - http://www.flightgear.org/~curt
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// Copyright (C) 2010 Torsten Dreyer - Torsten (at) t3r (dot) de
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//
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// This program is free software; you can redistribute it and/or
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// modify it under the terms of the GNU General Public License as
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// published by the Free Software Foundation; either version 2 of the
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// License, or (at your option) any later version.
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//
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// This program is distributed in the hope that it will be useful, but
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// WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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// General Public License for more details.
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//
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// You should have received a copy of the GNU General Public License
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// along with this program; if not, write to the Free Software
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// Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
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//
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#include "pidcontroller.hxx"
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using namespace FGXMLAutopilot;
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using std::endl;
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using std::cout;
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PIDController::PIDController():
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AnalogComponent(),
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alpha( 0.1 ),
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beta( 1.0 ),
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gamma( 0.0 ),
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ep_n_1( 0.0 ),
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edf_n_1( 0.0 ),
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edf_n_2( 0.0 ),
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u_n_1( 0.0 ),
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desiredTs( 0.0 ),
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elapsedTime( 0.0 )
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{
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}
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/*
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* Roy Vegard Ovesen:
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*
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* Ok! Here is the PID controller algorithm that I would like to see
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* implemented:
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*
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* delta_u_n = Kp * [ (ep_n - ep_n-1) + ((Ts/Ti)*e_n)
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* + (Td/Ts)*(edf_n - 2*edf_n-1 + edf_n-2) ]
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*
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* u_n = u_n-1 + delta_u_n
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*
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* where:
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*
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* delta_u : The incremental output
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* Kp : Proportional gain
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* ep : Proportional error with reference weighing
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* ep = beta * r - y
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* where:
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* beta : Weighing factor
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* r : Reference (setpoint)
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* y : Process value, measured
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* e : Error
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* e = r - y
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* Ts : Sampling interval
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* Ti : Integrator time
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* Td : Derivator time
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* edf : Derivate error with reference weighing and filtering
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* edf_n = edf_n-1 / ((Ts/Tf) + 1) + ed_n * (Ts/Tf) / ((Ts/Tf) + 1)
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* where:
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* Tf : Filter time
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* Tf = alpha * Td , where alpha usually is set to 0.1
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* ed : Unfiltered derivate error with reference weighing
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* ed = gamma * r - y
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* where:
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* gamma : Weighing factor
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*
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* u : absolute output
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*
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* Index n means the n'th value.
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*
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*
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* Inputs:
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* enabled ,
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* y_n , r_n , beta=1 , gamma=0 , alpha=0.1 ,
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* Kp , Ti , Td , Ts (is the sampling time available?)
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* u_min , u_max
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*
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* Output:
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* u_n
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*/
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void PIDController::update( bool firstTime, double dt )
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{
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double edf_n = 0.0;
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double u_n = 0.0; // absolute output
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double u_min = _minInput.get_value();
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double u_max = _maxInput.get_value();
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elapsedTime += dt;
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if( elapsedTime <= desiredTs ) {
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// do nothing if time step is not positive (i.e. no time has
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// elapsed)
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return;
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}
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double Ts = elapsedTime; // sampling interval (sec)
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elapsedTime = 0.0;
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if( firstTime ) {
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// first time being enabled, seed u_n with current
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// property tree value
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ep_n_1 = 0.0;
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edf_n_2 = edf_n_1 = edf_n = 0.0;
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u_n = get_output_value();
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u_n_1 = u_n;
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}
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if( Ts > SGLimitsd::min()) {
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if( _debug ) cout << "Updating " << get_name()
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<< " Ts " << Ts << endl;
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double y_n = _valueInput.get_value();
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double r_n = _referenceInput.get_value();
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if ( _debug ) cout << " input = " << y_n << " ref = " << r_n << endl;
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// Calculates proportional error:
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double ep_n = beta * r_n - y_n;
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if ( _debug ) cout << " ep_n = " << ep_n;
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if ( _debug ) cout << " ep_n_1 = " << ep_n_1;
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// Calculates error:
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double e_n = r_n - y_n;
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if ( _debug ) cout << " e_n = " << e_n;
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double td = Td.get_value();
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if ( td > 0.0 ) { // do we need to calcluate derivative error?
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// Calculates derivate error:
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double ed_n = gamma * r_n - y_n;
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if ( _debug ) cout << " ed_n = " << ed_n;
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// Calculates filter time:
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double Tf = alpha * td;
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if ( _debug ) cout << " Tf = " << Tf;
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// Filters the derivate error:
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edf_n = edf_n_1 / (Ts/Tf + 1)
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+ ed_n * (Ts/Tf) / (Ts/Tf + 1);
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if ( _debug ) cout << " edf_n = " << edf_n;
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} else {
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edf_n_2 = edf_n_1 = edf_n = 0.0;
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}
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// Calculates the incremental output:
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double ti = Ti.get_value();
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double delta_u_n = 0.0; // incremental output
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if ( ti > 0.0 ) {
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delta_u_n = Kp.get_value() * ( (ep_n - ep_n_1)
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+ ((Ts/ti) * e_n)
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+ ((td/Ts) * (edf_n - 2*edf_n_1 + edf_n_2)) );
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if ( _debug ) {
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cout << " delta_u_n = " << delta_u_n << endl;
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cout << "P:" << Kp.get_value() * (ep_n - ep_n_1)
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<< " I:" << Kp.get_value() * ((Ts/ti) * e_n)
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<< " D:" << Kp.get_value() * ((td/Ts) * (edf_n - 2*edf_n_1 + edf_n_2))
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<< endl;
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}
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}
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// Integrator anti-windup logic:
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if ( delta_u_n > (u_max - u_n_1) ) {
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delta_u_n = u_max - u_n_1;
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if ( _debug ) cout << " max saturation " << endl;
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} else if ( delta_u_n < (u_min - u_n_1) ) {
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delta_u_n = u_min - u_n_1;
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if ( _debug ) cout << " min saturation " << endl;
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}
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// Calculates absolute output:
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u_n = u_n_1 + delta_u_n;
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if ( _debug ) cout << " output = " << u_n << endl;
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// Updates indexed values;
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u_n_1 = u_n;
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ep_n_1 = ep_n;
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edf_n_2 = edf_n_1;
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edf_n_1 = edf_n;
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set_output_value( u_n );
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}
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}
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bool PIDController::configure( const std::string & nodeName, SGPropertyNode_ptr configNode )
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{
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SG_LOG( SG_AUTOPILOT, SG_BULK, "PIDController::configure(" << nodeName << ")" << endl );
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if( AnalogComponent::configure( nodeName, configNode ) )
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return true;
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if( nodeName == "config" ) {
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Component::configure( configNode );
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return true;
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}
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if (nodeName == "Ts") {
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desiredTs = configNode->getDoubleValue();
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return true;
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}
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if (nodeName == "Kp") {
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Kp.push_back( new InputValue(configNode) );
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return true;
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}
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if (nodeName == "Ti") {
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Ti.push_back( new InputValue(configNode) );
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return true;
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}
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if (nodeName == "Td") {
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Td.push_back( new InputValue(configNode) );
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return true;
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}
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if (nodeName == "beta") {
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beta = configNode->getDoubleValue();
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return true;
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}
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if (nodeName == "alpha") {
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alpha = configNode->getDoubleValue();
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return true;
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}
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if (nodeName == "gamma") {
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gamma = configNode->getDoubleValue();
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return true;
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}
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SG_LOG( SG_AUTOPILOT, SG_BULK, "PIDController::configure(" << nodeName << ") [unhandled]" << endl );
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return false;
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}
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