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// pidcontroller.hxx - implementation of PID controller
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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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// 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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// 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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// 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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// 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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#ifndef __PIDCONTROLLER_HXX
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#define __PIDCONTROLLER_HXX 1
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#include "analogcomponent.hxx"
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#include <simgear/props/props.hxx>
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#include <simgear/structure/subsystem_mgr.hxx>
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namespace FGXMLAutopilot {
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* Roy Ovesen's PID controller
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class PIDController : public AnalogComponent {
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// Configuration values
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InputValueList Kp; // proportional gain
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InputValueList Ti; // Integrator time (sec)
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InputValueList Td; // Derivator time (sec)
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double alpha; // low pass filter weighing factor (usually 0.1)
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double beta; // process value weighing factor for
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// calculating proportional error
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double gamma; // process value weighing factor for
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// calculating derivative error
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// Previous state tracking values
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double ep_n_1; // ep[n-1] (prop error)
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double edf_n_1; // edf[n-1] (derivative error)
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double edf_n_2; // edf[n-2] (derivative error)
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double u_n_1; // u[n-1] (output)
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double desiredTs; // desired sampling interval (sec)
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double elapsedTime; // elapsed time (sec)
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bool configure( const std::string & nodeName, SGPropertyNode_ptr configNode);
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void update( bool firstTime, double dt );
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#endif // __PIDCONTROLLER_HXX