ardupilot/libraries/AP_Controller/AP_Controller.h

/*
 * AP_Controller.h
 * Copyright (C) James Goppert 2010 <james.goppert@gmail.com>
 *
 * This file is free software: you can redistribute it and/or modify it
 * under the terms of the GNU General Public License as published by the
 * Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This file 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 General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License along
 * with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

#ifndef AP_Controller_H
#define AP_Controller_H

#include <AP_Common.h>
#include <AP_Vector.h>
#include <AP_Var.h>
#include <APM_RC.h>
#include "AP_RcChannel.h"

const float one = 1.0;
const float zero = 0.0;
const float negativeOne = -1.0;

/// Controller class
class AP_Controller
{
public:
    class Block
    {
    public:
        Block() :
            _input(), _output()
        {
        }
        virtual void update(const float & dt) = 0;
        virtual void connect( Block * block)
        {
            if (!block) return;
            for (int i=0;i<block->getOutput().getSize();i++)
                _input.push_back(block->getOutput()[i]);
        }
        const Vector < float * > & getOutput() const { return _output; }
        const float & input(int i) { return (*_input[i]);}
        float & output(int i) { return (*_output[i]);}
    protected:
        Vector< const float * > _input;
        Vector< float * > _output;
    };

    void addBlock(Block * block)
    {
        if (!block)
        {
            Serial.println("Attempint to add a null block");
            return;
        }
        if (_blocks.getSize() > 0) 
        {
            if (_blocks[_blocks.getSize()-1] == NULL)
            {
                Serial.println("Attempted to connect to null block");
                return;
            }
            else
            {
                block->connect(_blocks[_blocks.getSize()-1]);
            }
        }
        _blocks.push_back(block);
    }
    virtual void update(const double dt)
    {
        for (int i=0;i<_blocks.getSize();i++)
        {
            if (!_blocks[i]) continue;
            _blocks[i]->update(dt);
        }
    }

  private:
    Vector<Block * > _blocks;   
};


/// Servo Block
class ToServo : public AP_Controller::Block
{
public:
    ToServo(AP_RcChannel * ch) : _ch(ch)
    {
    }
    // doesn't connect
    virtual void connect(Block * block) {};
    virtual void update(const float & dt = 0)
    {
        if (_input.getSize() > 0)
        {
            _ch->setNormalized(input(0));
        }
    }
private:
    float _position;
    AP_RcChannel * _ch;
};

/// SumGain
class SumGain : public AP_Controller::Block
{
public:
    /// Constructor that allows 1-8 sum gain pairs, more
    /// can be added if necessary
    SumGain(
            const float * var1 = NULL, const float * gain1 = NULL,
            const float * var2 = NULL, const float * gain2 = NULL,
            const float * var3 = NULL, const float * gain3 = NULL,
            const float * var4 = NULL, const float * gain4 = NULL,
            const float * var5 = NULL, const float * gain5 = NULL,
            const float * var6 = NULL, const float * gain6 = NULL,
            const float * var7 = NULL, const float * gain7 = NULL,
            const float * var8 = NULL, const float * gain8 = NULL)
    {
        if ( (var1 != NULL) && (gain1 != NULL) ) add(var1,gain1);
        if ( (var2 != NULL) && (gain2 != NULL) ) add(var2,gain2);
        if ( (var3 != NULL) && (gain3 != NULL) ) add(var3,gain3);
        if ( (var4 != NULL) && (gain4 != NULL) ) add(var4,gain4);
        if ( (var5 != NULL) && (gain5 != NULL) ) add(var5,gain5);
        if ( (var6 != NULL) && (gain6 != NULL) ) add(var6,gain6);
        if ( (var7 != NULL) && (gain7 != NULL) ) add(var7,gain7);
        if ( (var8 != NULL) && (gain8 != NULL) ) add(var8,gain8);

        // create output
        _output.push_back(new float(0.0));
    }
    void add(const float * var, const float * gain)
    {
        _input.push_back(var);
        _gain.push_back(gain);
    }
    virtual void update(const float & dt = 0)
    {
        if (_output.getSize() < 1) return;
        float sum =0;
        for (int i=0;i<_input.getSize();i++) sum += input(i) * gain(i);
        output(0) = sum;
    }
    float gain(int i) { return *(_gain[i]); }
private:
    Vector<const float *> _gain;
};


/// PID block
class Pid : public AP_Controller::Block
{
public:
    Pid(AP_Var::Key key, const prog_char_t * name,
            float kP = 0.0,
            float kI = 0.0,
            float kD = 0.0,
            float iMax = 0.0,
            uint8_t dFcut = 20.0
            ) :
        _group(key,name),
        _eP(0),
        _eI(0),
        _eD(0),
        _kP(&_group,1,kP,PSTR("P")), 
        _kI(&_group,2,kI,PSTR("I")), 
        _kD(&_group,3,kD,PSTR("D")), 
        _iMax(&_group,4,iMax,PSTR("IMAX")), 
        _fCut(&_group,5,dFcut,PSTR("FCUT"))
    {
        // create output
        _output.push_back(new float(0.0));
    }
    
    virtual void update(const float & dt)
    {
        if (_output.getSize() < 1 || (!_input[0]) || (!_output[0]) ) return;

        // derivative with low pass
        float RC = 1/(2*M_PI*_fCut); // low pass filter
        _eD =  _eD + ( ( _eP - input(0) )/dt - _eD ) * (dt / (dt + RC));

        // proportional, note must come after derivative
        // because derivatve uses _eP as previous value
        _eP = input(0);

        // integral
        _eI += _eP*dt;

        // wind up guard
        if (_eI > _iMax) _eI = _iMax;
        else if (_eI < -_iMax) _eI = -_iMax;

        // pid sum
        output(0) = _kP*_eP + _kI*_eI +  _kD*_eD;

        // debug output
        /*
        Serial.println("kP, kI, kD: ");
        Serial.print(_kP,5); Serial.print(" ");
        Serial.print(_kI,5); Serial.print(" ");
        Serial.println(_kD,5);
        Serial.print("eP, eI, eD: ");
        Serial.print(_eP,5); Serial.print(" ");
        Serial.print(_eI,5); Serial.print(" ");
        Serial.println(_eD,5);
        Serial.print("input: ");
        Serial.println(input(0),5);
        Serial.print("output: ");
        Serial.println(output(0),5);
        */
    }
private:
    AP_Var_group _group; /// helps with parameter management
    AP_Float _eP; /// input
    AP_Float _eI; /// integral of input
    AP_Float _eD; /// derivative of input
    AP_Float _kP; /// proportional gain
    AP_Float _kI; /// integral gain
    AP_Float _kD; /// derivative gain
    AP_Float _iMax; /// integrator saturation
    AP_Uint8 _fCut; /// derivative low-pass cut freq (Hz)
};

/// Sink block
/// saves input port to variable
class Sink : public AP_Controller::Block
{
public:
    Sink(float & var, uint8_t port=0) :
        _var(var), _port(port)
    {
    }
    virtual void update(const float & dt)
    {
        _var = input(_port); 
    }
    // doesn't connect
    virtual void connect(Block * block) {}
private:
    float & _var;
    uint8_t _port;
};

/// Saturate block
/// Constrains output to a range
class Saturate : public AP_Controller::Block
{
public:
    Saturate(float & min, float & max, uint8_t port=0) :
        _min(min), _max(max), _port(port)
    {
        // create output
        _output.push_back(new float(0.0));
    }
    virtual void update(const float & dt)
    {
        float u = input(_port); 
        if (u>_max) u = _max;
        if (u<_min) u = _min;
        output(_port) = u;
    }
private:
    uint8_t _port;
    float & _min;
    float & _max;
};

#endif // AP_Controller_H

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