427 lines
13 KiB
C++
427 lines
13 KiB
C++
// digitalfilter.cxx - a selection of digital filters
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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 "digitalfilter.hxx"
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#include "functor.hxx"
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#include <deque>
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using std::map;
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using std::string;
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using std::endl;
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using std::cout;
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namespace FGXMLAutopilot {
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/**
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*
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*
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*/
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class DigitalFilterImplementation : public SGReferenced {
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protected:
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virtual bool configure( const std::string & nodeName, SGPropertyNode_ptr configNode) = 0;
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public:
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virtual ~DigitalFilterImplementation() {}
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DigitalFilterImplementation();
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virtual void initialize( double output ) {}
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virtual double compute( double dt, double input ) = 0;
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bool configure( SGPropertyNode_ptr configNode );
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void setDigitalFilter( DigitalFilter * digitalFilter ) { _digitalFilter = digitalFilter; }
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protected:
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DigitalFilter * _digitalFilter;
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};
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/* --------------------------------------------------------------------------------- */
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/* --------------------------------------------------------------------------------- */
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class GainFilterImplementation : public DigitalFilterImplementation {
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protected:
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InputValueList _gainInput;
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bool configure( const std::string & nodeName, SGPropertyNode_ptr configNode );
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public:
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GainFilterImplementation() : _gainInput(1.0) {}
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double compute( double dt, double input );
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};
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class ReciprocalFilterImplementation : public GainFilterImplementation {
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public:
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double compute( double dt, double input );
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};
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class DerivativeFilterImplementation : public GainFilterImplementation {
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InputValueList _TfInput;
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double _input_1;
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bool configure( const std::string & nodeName, SGPropertyNode_ptr configNode );
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public:
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DerivativeFilterImplementation();
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double compute( double dt, double input );
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};
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class ExponentialFilterImplementation : public GainFilterImplementation {
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protected:
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InputValueList _TfInput;
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bool configure( const std::string & nodeName, SGPropertyNode_ptr configNode );
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bool _isSecondOrder;
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double output_1, output_2;
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public:
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ExponentialFilterImplementation();
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double compute( double dt, double input );
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virtual void initialize( double output );
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};
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class MovingAverageFilterImplementation : public DigitalFilterImplementation {
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protected:
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InputValueList _samplesInput;
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double _output_1;
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std::deque <double> _inputQueue;
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bool configure( const std::string & nodeName, SGPropertyNode_ptr configNode );
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public:
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MovingAverageFilterImplementation();
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double compute( double dt, double input );
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virtual void initialize( double output );
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};
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class NoiseSpikeFilterImplementation : public DigitalFilterImplementation {
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protected:
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double _output_1;
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InputValueList _rateOfChangeInput;
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bool configure( const std::string & nodeName, SGPropertyNode_ptr configNode );
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public:
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NoiseSpikeFilterImplementation();
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double compute( double dt, double input );
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virtual void initialize( double output );
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};
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/* --------------------------------------------------------------------------------- */
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/* --------------------------------------------------------------------------------- */
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} // namespace FGXMLAutopilot
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using namespace FGXMLAutopilot;
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/* --------------------------------------------------------------------------------- */
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/* --------------------------------------------------------------------------------- */
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DigitalFilterImplementation::DigitalFilterImplementation() :
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_digitalFilter(NULL)
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{
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}
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bool DigitalFilterImplementation::configure( SGPropertyNode_ptr configNode )
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{
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for (int i = 0; i < configNode->nChildren(); ++i ) {
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SGPropertyNode_ptr prop;
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SGPropertyNode_ptr child = configNode->getChild(i);
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string cname(child->getName());
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if( configure( cname, child ) )
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continue;
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} // for configNode->nChildren()
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return true;
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}
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/* --------------------------------------------------------------------------------- */
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/* --------------------------------------------------------------------------------- */
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double GainFilterImplementation::compute( double dt, double input )
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{
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return _gainInput.get_value() * input;
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}
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bool GainFilterImplementation::configure( const std::string & nodeName, SGPropertyNode_ptr configNode )
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{
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if (nodeName == "gain" ) {
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_gainInput.push_back( new InputValue( configNode, 1 ) );
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return true;
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}
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return false;
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}
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/* --------------------------------------------------------------------------------- */
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/* --------------------------------------------------------------------------------- */
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double ReciprocalFilterImplementation::compute( double dt, double input )
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{
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if( input >= -SGLimitsd::min() && input <= SGLimitsd::min() )
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return SGLimitsd::max();
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return _gainInput.get_value() / input;
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}
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/* --------------------------------------------------------------------------------- */
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/* --------------------------------------------------------------------------------- */
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DerivativeFilterImplementation::DerivativeFilterImplementation() :
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_input_1(0.0)
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{
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}
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bool DerivativeFilterImplementation::configure( const std::string & nodeName, SGPropertyNode_ptr configNode )
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{
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if( GainFilterImplementation::configure( nodeName, configNode ) )
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return true;
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if (nodeName == "filter-time" ) {
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_TfInput.push_back( new InputValue( configNode, 1 ) );
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return true;
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}
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return false;
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}
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double DerivativeFilterImplementation::compute( double dt, double input )
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{
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double output = (input - _input_1) * _TfInput.get_value() * _gainInput.get_value() / dt;
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_input_1 = input;
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return output;
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}
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/* --------------------------------------------------------------------------------- */
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/* --------------------------------------------------------------------------------- */
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MovingAverageFilterImplementation::MovingAverageFilterImplementation() :
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_output_1(0.0)
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{
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}
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void MovingAverageFilterImplementation::initialize( double output )
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{
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_output_1 = output;
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}
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double MovingAverageFilterImplementation::compute( double dt, double input )
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{
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std::deque<double>::size_type samples = _samplesInput.get_value();
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_inputQueue.resize(samples+1, 0.0);
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double output_0 = _output_1 + (input - _inputQueue.back()) / samples;
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_output_1 = output_0;
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_inputQueue.push_front(input);
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return output_0;
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}
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bool MovingAverageFilterImplementation::configure( const std::string & nodeName, SGPropertyNode_ptr configNode )
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{
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if (nodeName == "samples" ) {
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_samplesInput.push_back( new InputValue( configNode, 1 ) );
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return true;
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}
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return false;
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}
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/* --------------------------------------------------------------------------------- */
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/* --------------------------------------------------------------------------------- */
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NoiseSpikeFilterImplementation::NoiseSpikeFilterImplementation() :
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_output_1(0.0)
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{
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}
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void NoiseSpikeFilterImplementation::initialize( double output )
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{
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_output_1 = output;
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}
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double NoiseSpikeFilterImplementation::compute( double dt, double input )
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{
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double delta = input - _output_1;
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if( fabs(delta) <= SGLimitsd::min() ) return input; // trivial
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double maxChange = _rateOfChangeInput.get_value() * dt;
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const PeriodicalValue * periodical = _digitalFilter->getPeriodicalValue();
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if( periodical ) delta = periodical->normalizeSymmetric( delta );
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if( fabs(delta) <= maxChange )
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return (_output_1 = input);
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else
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return (_output_1 = _output_1 + copysign( maxChange, delta ));
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}
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bool NoiseSpikeFilterImplementation::configure( const std::string & nodeName, SGPropertyNode_ptr configNode )
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{
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if (nodeName == "max-rate-of-change" ) {
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_rateOfChangeInput.push_back( new InputValue( configNode, 1 ) );
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return true;
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}
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return false;
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}
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/* --------------------------------------------------------------------------------- */
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/* --------------------------------------------------------------------------------- */
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ExponentialFilterImplementation::ExponentialFilterImplementation()
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: _isSecondOrder(false),
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output_1(0.0),
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output_2(0.0)
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{
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}
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void ExponentialFilterImplementation::initialize( double output )
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{
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output_1 = output_2 = output;
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}
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double ExponentialFilterImplementation::compute( double dt, double input )
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{
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input = GainFilterImplementation::compute( dt, input );
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double tf = _TfInput.get_value();
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double output_0;
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// avoid negative filter times
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// and div by zero if -tf == dt
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double alpha = tf > 0.0 ? 1 / ((tf/dt) + 1) : 1.0;
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if(_isSecondOrder) {
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output_0 = alpha * alpha * input +
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2 * (1 - alpha) * output_1 -
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(1 - alpha) * (1 - alpha) * output_2;
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} else {
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output_0 = alpha * input + (1 - alpha) * output_1;
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}
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output_2 = output_1;
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return (output_1 = output_0);
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}
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bool ExponentialFilterImplementation::configure( const std::string & nodeName, SGPropertyNode_ptr configNode )
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{
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if( GainFilterImplementation::configure( nodeName, configNode ) )
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return true;
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if (nodeName == "filter-time" ) {
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_TfInput.push_back( new InputValue( configNode, 1 ) );
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return true;
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}
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if (nodeName == "type" ) {
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string type(configNode->getStringValue());
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_isSecondOrder = type == "double-exponential";
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}
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return false;
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}
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/* --------------------------------------------------------------------------------- */
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/* Digital Filter Component Implementation */
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/* --------------------------------------------------------------------------------- */
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DigitalFilter::DigitalFilter() :
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AnalogComponent(),
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_initializeTo(INITIALIZE_INPUT)
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{
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}
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DigitalFilter::~DigitalFilter()
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{
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}
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static map<string,FunctorBase<DigitalFilterImplementation> *> componentForge;
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bool DigitalFilter::configure(const string& nodeName, SGPropertyNode_ptr configNode)
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{
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if( componentForge.empty() ) {
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componentForge["gain"] = new CreateAndConfigureFunctor<GainFilterImplementation,DigitalFilterImplementation>();
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componentForge["exponential"] = new CreateAndConfigureFunctor<ExponentialFilterImplementation,DigitalFilterImplementation>();
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componentForge["double-exponential"] = new CreateAndConfigureFunctor<ExponentialFilterImplementation,DigitalFilterImplementation>();
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componentForge["moving-average"] = new CreateAndConfigureFunctor<MovingAverageFilterImplementation,DigitalFilterImplementation>();
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componentForge["noise-spike"] = new CreateAndConfigureFunctor<NoiseSpikeFilterImplementation,DigitalFilterImplementation>();
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componentForge["reciprocal"] = new CreateAndConfigureFunctor<ReciprocalFilterImplementation,DigitalFilterImplementation>();
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componentForge["derivative"] = new CreateAndConfigureFunctor<DerivativeFilterImplementation,DigitalFilterImplementation>();
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}
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SG_LOG( SG_AUTOPILOT, SG_BULK, "DigitalFilter::configure(" << nodeName << ")" << endl );
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if( AnalogComponent::configure( nodeName, configNode ) )
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return true;
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if (nodeName == "type" ) {
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string type( configNode->getStringValue() );
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if( componentForge.count(type) == 0 ) {
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SG_LOG( SG_AUTOPILOT, SG_BULK, "unhandled filter type <" << type << ">" << endl );
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return true;
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}
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_implementation = (*componentForge[type])( configNode->getParent() );
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_implementation->setDigitalFilter( this );
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return true;
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}
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if( nodeName == "initialize-to" ) {
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string s( configNode->getStringValue() );
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if( s == "input" ) {
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_initializeTo = INITIALIZE_INPUT;
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} else if( s == "output" ) {
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_initializeTo = INITIALIZE_OUTPUT;
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} else if( s == "none" ) {
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_initializeTo = INITIALIZE_NONE;
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} else {
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SG_LOG( SG_AUTOPILOT, SG_WARN, "unhandled initialize-to value '" << s << "' ignored" );
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}
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return true;
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}
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SG_LOG( SG_AUTOPILOT, SG_BULK, "DigitalFilter::configure(" << nodeName << ") [unhandled]" << endl );
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return false; // not handled by us, let the base class try
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}
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void DigitalFilter::update( bool firstTime, double dt)
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{
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if( _implementation == NULL ) return;
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if( firstTime ) {
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switch( _initializeTo ) {
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case INITIALIZE_INPUT:
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SG_LOG(SG_AUTOPILOT,SG_DEBUG, "First time initialization of " << get_name() << " to " << _valueInput.get_value() );
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_implementation->initialize( _valueInput.get_value() );
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break;
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case INITIALIZE_OUTPUT:
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SG_LOG(SG_AUTOPILOT,SG_DEBUG, "First time initialization of " << get_name() << " to " << get_output_value() );
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_implementation->initialize( get_output_value() );
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break;
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default:
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SG_LOG(SG_AUTOPILOT,SG_DEBUG, "First time initialization of " << get_name() << " to (uninitialized)" );
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break;
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}
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}
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double input = _valueInput.get_value() - _referenceInput.get_value();
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double output = _implementation->compute( dt, input );
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set_output_value( output );
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if(_debug) {
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cout << "input:" << input
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<< "\toutput:" << output << endl;
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}
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}
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