1 // pisimplecontroller.cxx - implementation of a simple PI controller
3 // Written by Torsten Dreyer
4 // Based heavily on work created by Curtis Olson, started January 2004.
6 // Copyright (C) 2004 Curtis L. Olson - http://www.flightgear.org/~curt
7 // Copyright (C) 2010 Torsten Dreyer - Torsten (at) t3r (dot) de
9 // This program is free software; you can redistribute it and/or
10 // modify it under the terms of the GNU General Public License as
11 // published by the Free Software Foundation; either version 2 of the
12 // License, or (at your option) any later version.
14 // This program is distributed in the hope that it will be useful, but
15 // WITHOUT ANY WARRANTY; without even the implied warranty of
16 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
17 // General Public License for more details.
19 // You should have received a copy of the GNU General Public License
20 // along with this program; if not, write to the Free Software
21 // Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
24 #include "pisimplecontroller.hxx"
26 using namespace FGXMLAutopilot;
28 //------------------------------------------------------------------------------
29 PISimpleController::PISimpleController() :
35 //------------------------------------------------------------------------------
36 bool PISimpleController::configure( SGPropertyNode& cfg_node,
37 const std::string& cfg_name,
38 SGPropertyNode& prop_root )
40 if( AnalogComponent::configure(cfg_node, cfg_name, prop_root) )
43 if( cfg_name == "config" ) {
44 Component::configure(prop_root, cfg_node);
48 if (cfg_name == "Kp") {
49 _Kp.push_back( new InputValue(prop_root, cfg_node) );
53 if (cfg_name == "Ki") {
54 _Ki.push_back( new InputValue(prop_root, cfg_node) );
61 void PISimpleController::update( bool firstTime, double dt )
64 // we have just been enabled, zero out int_sum
68 if ( _debug ) std::cout << "Updating " << get_name() << std::endl;
69 double y_n = _valueInput.get_value();
70 double r_n = _referenceInput.get_value();
72 double error = r_n - y_n;
73 if ( _debug ) std::cout << "input = " << y_n
74 << " reference = " << r_n
75 << " error = " << error
78 double prop_comp = clamp(error * _Kp.get_value());
79 _int_sum += error * _Ki.get_value() * dt;
82 double output = prop_comp + _int_sum;
83 double clamped_output = clamp( output );
84 if( output != clamped_output ) // anti-windup
85 _int_sum = clamped_output - prop_comp;
87 if ( _debug ) std::cout << "prop_comp = " << prop_comp
88 << " int_sum = " << _int_sum << std::endl;
90 set_output_value( clamped_output );
91 if ( _debug ) std::cout << "output = " << clamped_output << std::endl;