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AC_PID: library update and additional functions 

includes corrections from peer review
This commit is contained in:
Leonard Hall 2020-01-04 16:55:34 +10:30 committed by Randy Mackay
parent bc0da915c4
commit 1d720cc5e9
11 changed files with 660 additions and 246 deletions
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2
libraries/AC_PID/AC_P.h
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@ -1,7 +1,7 @@
#pragma once #pragma once
/// @file AC_PD.h /// @file AC_PD.h
/// @brief Generic PID algorithm, with EEPROM-backed storage of constants. /// @brief Generic P controller with EEPROM-backed storage of constants.
#include <AP_Common/AP_Common.h> #include <AP_Common/AP_Common.h>
#include <AP_Param/AP_Param.h> #include <AP_Param/AP_Param.h>

257
libraries/AC_PID/AC_PID_2D.cpp
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@ -23,13 +23,13 @@ const AP_Param::GroupInfo AC_PID_2D::var_info[] = {
// @Param: IMAX // @Param: IMAX
// @DisplayName: PID Integral Maximum // @DisplayName: PID Integral Maximum
// @Description: The maximum/minimum value that the I term can output // @Description: The maximum/minimum value that the I term can output
AP_GROUPINFO("IMAX", 2, AC_PID_2D, _imax, 0), AP_GROUPINFO("IMAX", 2, AC_PID_2D, _kimax, 0),
// @Param: FILT // @Param: FILT
// @DisplayName: PID Input filter frequency in Hz // @DisplayName: PID Input filter frequency in Hz
// @Description: Input filter frequency in Hz // @Description: Input filter frequency in Hz
// @Units: Hz // @Units: Hz
AP_GROUPINFO("FILT", 3, AC_PID_2D, _filt_hz, AC_PID_2D_FILT_HZ_DEFAULT), AP_GROUPINFO("FILT", 3, AC_PID_2D, _filt_E_hz, AC_PID_2D_FILT_HZ_DEFAULT),
// @Param: D // @Param: D
// @DisplayName: PID Derivative Gain // @DisplayName: PID Derivative Gain
@ -40,173 +40,105 @@ const AP_Param::GroupInfo AC_PID_2D::var_info[] = {
// @DisplayName: D term filter frequency in Hz // @DisplayName: D term filter frequency in Hz
// @Description: D term filter frequency in Hz // @Description: D term filter frequency in Hz
// @Units: Hz // @Units: Hz
AP_GROUPINFO("D_FILT", 5, AC_PID_2D, _filt_d_hz, AC_PID_2D_FILT_D_HZ_DEFAULT), AP_GROUPINFO("D_FILT", 5, AC_PID_2D, _filt_D_hz, AC_PID_2D_FILT_D_HZ_DEFAULT),
// @Param: FF
// @DisplayName: PID Feed Forward Gain
// @Description: FF Gain which produces an output that is proportional to the magnitude of the target
AP_GROUPINFO("FF", 6, AC_PID_2D, _kff, 0),
AP_GROUPEND AP_GROUPEND
}; };
// Constructor // Constructor
AC_PID_2D::AC_PID_2D(float initial_p, float initial_i, float initial_d, float initial_imax, float initial_filt_hz, float initial_filt_d_hz, float dt) : AC_PID_2D::AC_PID_2D(float initial_kP, float initial_kI, float initial_kD, float initial_kFF, float initial_imax, float initial_filt_E_hz, float initial_filt_D_hz, float dt) :
_dt(dt) _dt(dt)
{ {
// load parameter values from eeprom // load parameter values from eeprom
AP_Param::setup_object_defaults(this, var_info); AP_Param::setup_object_defaults(this, var_info);
_kp = initial_p; _kp = initial_kP;
_ki = initial_i; _ki = initial_kI;
_kd = initial_d; _kd = initial_kD;
_imax = fabsf(initial_imax); _kff = initial_kFF;
filt_hz(initial_filt_hz); _kimax = fabsf(initial_imax);
filt_d_hz(initial_filt_d_hz); filt_E_hz(initial_filt_E_hz);
filt_D_hz(initial_filt_D_hz);
// reset input filter to first value received and derivitive to zero // reset input filter to first value received
reset_filter(); _reset_filter = true;
} }
// set_dt - set time step in seconds // update_all - set target and measured inputs to PID controller and calculate outputs
void AC_PID_2D::set_dt(float dt) // target and error are filtered
{ // the derivative is then calculated and filtered
// set dt and calculate the input filter alpha // the integral is then updated based on the setting of the limit flag
_dt = dt; Vector2f AC_PID_2D::update_all(const Vector2f &target, const Vector2f &measurement, bool limit)
calc_filt_alpha();
calc_filt_alpha_d();
}
// filt_hz - set input filter hz
void AC_PID_2D::filt_hz(float hz)
{
_filt_hz.set(fabsf(hz));
// sanity check _filt_hz
_filt_hz = MAX(_filt_hz, AC_PID_2D_FILT_HZ_MIN);
// calculate the input filter alpha
calc_filt_alpha();
}
// filt_d_hz - set input filter hz
void AC_PID_2D::filt_d_hz(float hz)
{
_filt_d_hz.set(fabsf(hz));
// sanity check _filt_hz
_filt_d_hz = MAX(_filt_d_hz, AC_PID_2D_FILT_D_HZ_MIN);
// calculate the input filter alpha
calc_filt_alpha_d();
}
// set_input - set input to PID controller
// input is filtered before the PID controllers are run
// this should be called before any other calls to get_p, get_i or get_d
void AC_PID_2D::set_input(const Vector2f &input)
{ {
// don't process inf or NaN // don't process inf or NaN
if (!isfinite(input.x) || !isfinite(input.y)) { if (target.is_nan() || target.is_inf() ||
return; measurement.is_nan() || measurement.is_inf()) {
return Vector2f{};
} }
_target = target;
// reset input filter to value received // reset input filter to value received
if (_flags._reset_filter) { if (_reset_filter) {
_flags._reset_filter = false; _reset_filter = false;
_input = input; _error = _target - measurement;
_derivative.zero();
} else {
Vector2f error_last{_error};
_error += ((_target - measurement) - _error) * get_filt_E_alpha();
// calculate and filter derivative
if (_dt > 0.0f) {
const Vector2f derivative{(_error - error_last) / _dt};
_derivative += (derivative - _derivative) * get_filt_D_alpha();
}
} }
// update filter and calculate derivative // update I term
const Vector2f input_delta = (input - _input) * _filt_alpha; update_i(limit);
_input += input_delta;
set_input_filter_d(input_delta); _pid_info_x.target = _target.x;
_pid_info_x.actual = measurement.x;
_pid_info_x.error = _error.x;
_pid_info_x.P = _error.x * _kp;
_pid_info_x.I = _integrator.x;
_pid_info_x.D = _derivative.x * _kd;
_pid_info_x.FF = _target.x * _kff;
_pid_info_y.target = _target.y;
_pid_info_y.actual = measurement.y;
_pid_info_y.error = _error.y;
_pid_info_y.P = _error.y * _kp;
_pid_info_y.I = _integrator.y;
_pid_info_y.D = _derivative.y * _kd;
_pid_info_y.FF = _target.y * _kff;
return _error * _kp + _integrator + _derivative * _kd + _target * _kff;
} }
// set_input_filter_d - set input to PID controller Vector2f AC_PID_2D::update_all(const Vector3f &target, const Vector3f &measurement, bool limit)
// only input to the D portion of the controller is filtered
// this should be called before any other calls to get_p, get_i or get_d
void AC_PID_2D::set_input_filter_d(const Vector2f& input_delta)
{ {
// don't process inf or NaN return update_all(Vector2f{target.x, target.y}, Vector2f{measurement.x, measurement.y}, limit);
if (!isfinite(input_delta.x) && !isfinite(input_delta.y)) {
return;
} }
// update filter and calculate derivative // update_i - update the integral
if (is_positive(_dt)) { // If the limit flag is set the integral is only allowed to shrink
const Vector2f derivative = input_delta / _dt; void AC_PID_2D::update_i(bool limit)
const Vector2f delta_derivative = (derivative - _derivative) * _filt_alpha_d;
_derivative += delta_derivative;
}
}
Vector2f AC_PID_2D::get_p() const
{ {
return (_input * _kp); float integrator_length_orig = _kimax;
if (limit) {
integrator_length_orig = MIN(integrator_length_orig, _integrator.length());
} }
_integrator += (_error * _ki) * _dt;
Vector2f AC_PID_2D::get_i()
{
if (!is_zero(_ki) && !is_zero(_dt)) {
_integrator += (_input * _ki) * _dt;
const float integrator_length = _integrator.length();
if ((integrator_length > _imax) && is_positive(integrator_length)) {
_integrator *= (_imax / integrator_length);
}
return _integrator;
}
return Vector2f();
}
// get_i_shrink - get_i but do not allow integrator to grow in length (it may shrink)
Vector2f AC_PID_2D::get_i_shrink()
{
if (!is_zero(_ki) && !is_zero(_dt)) {
const float integrator_length_orig = MIN(_integrator.length(), _imax);
_integrator += (_input * _ki) * _dt;
const float integrator_length_new = _integrator.length(); const float integrator_length_new = _integrator.length();
if ((integrator_length_new > integrator_length_orig) && is_positive(integrator_length_new)) { if (integrator_length_new > integrator_length_orig) {
_integrator *= (integrator_length_orig / integrator_length_new); _integrator *= (integrator_length_orig / integrator_length_new);
} }
return _integrator;
}
return Vector2f();
}
Vector2f AC_PID_2D::get_d()
{
// derivative component
return Vector2f(_kd * _derivative.x, _kd * _derivative.y);
}
Vector2f AC_PID_2D::get_pid()
{
return get_p() + get_i() + get_d();
}
void AC_PID_2D::reset_I()
{
_integrator.zero();
}
void AC_PID_2D::reset_filter()
{
_flags._reset_filter = true;
_derivative.x = 0.0f;
_derivative.y = 0.0f;
_integrator.zero();
}
void AC_PID_2D::load_gains()
{
_kp.load();
_ki.load();
_kd.load();
_imax.load();
_imax = fabsf(_imax);
_filt_hz.load();
_filt_d_hz.load();
// calculate the input filter alpha
calc_filt_alpha();
calc_filt_alpha_d();
} }
// save_gains - save gains to eeprom // save_gains - save gains to eeprom
@ -215,33 +147,40 @@ void AC_PID_2D::save_gains()
_kp.save(); _kp.save();
_ki.save(); _ki.save();
_kd.save(); _kd.save();
_imax.save(); _kff.save();
_filt_hz.save(); _kimax.save();
_filt_d_hz.save(); _filt_E_hz.save();
_filt_D_hz.save();
} }
// calc_filt_alpha - recalculate the input filter alpha // get the target filter alpha
void AC_PID_2D::calc_filt_alpha() float AC_PID_2D::get_filt_E_alpha() const
{ {
if (is_zero(_filt_hz)) { return calc_lowpass_alpha_dt(_dt, _filt_E_hz);
_filt_alpha = 1.0f;
return;
} }
// calculate alpha // get the derivative filter alpha
const float rc = 1/(M_2PI*_filt_hz); float AC_PID_2D::get_filt_D_alpha() const
_filt_alpha = _dt / (_dt + rc);
}
// calc_filt_alpha - recalculate the input filter alpha
void AC_PID_2D::calc_filt_alpha_d()
{ {
if (is_zero(_filt_d_hz)) { return calc_lowpass_alpha_dt(_dt, _filt_D_hz);
_filt_alpha_d = 1.0f;
return;
} }
// calculate alpha void AC_PID_2D::set_integrator(const Vector2f& target, const Vector2f& measurement, const Vector2f& i)
const float rc = 1/(M_2PI*_filt_d_hz); {
_filt_alpha_d = _dt / (_dt + rc); set_integrator(target - measurement, i);
} }
void AC_PID_2D::set_integrator(const Vector2f& error, const Vector2f& i)
{
set_integrator(i - error * _kp);
}
void AC_PID_2D::set_integrator(const Vector2f& i)
{
_integrator = i;
const float integrator_length = _integrator.length();
if (integrator_length > _kimax) {
_integrator *= (_kimax / integrator_length);
}
}

110
libraries/AC_PID/AC_PID_2D.h
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@ -7,6 +7,7 @@
#include <AP_Param/AP_Param.h> #include <AP_Param/AP_Param.h>
#include <stdlib.h> #include <stdlib.h>
#include <cmath> #include <cmath>
#include <AP_Logger/AP_Logger.h>
/// @class AC_PID_2D /// @class AC_PID_2D
/// @brief Copter PID control class /// @brief Copter PID control class
@ -14,32 +15,33 @@ class AC_PID_2D {
public: public:
// Constructor for PID // Constructor for PID
AC_PID_2D(float initial_p, float initial_i, float initial_d, float initial_imax, float initial_filt_hz, float initial_filt_d_hz, float dt); AC_PID_2D(float initial_kP, float initial_kI, float initial_kD, float initial_kFF, float initial_imax, float initial_filt_hz, float initial_filt_d_hz, float dt);
// set_dt - set time step in seconds // set time step in seconds
void set_dt(float dt); void set_dt(float dt) { _dt = dt; }
// set_input - set input to PID controller // update_all - set target and measured inputs to PID controller and calculate outputs
// input is filtered before the PID controllers are run // target and error are filtered
// this should be called before any other calls to get_p, get_i or get_d // the derivative is then calculated and filtered
void set_input(const Vector2f &input); // the integral is then updated based on the setting of the limit flag
void set_input(const Vector3f &input) { set_input(Vector2f(input.x, input.y)); } Vector2f update_all(const Vector2f &target, const Vector2f &measurement, bool limit = false);
Vector2f update_all(const Vector3f &target, const Vector3f &measurement, bool limit = false);
// get_pi - get results from pid controller // update the integral
Vector2f get_pid(); // if the limit flag is set the integral is only allowed to shrink
void update_i(bool limit);
// get results from pid controller
Vector2f get_p() const; Vector2f get_p() const;
Vector2f get_i(); Vector2f get_i() const;
Vector2f get_i_shrink(); // get_i but do not allow integrator to grow (it may shrink) Vector2f get_d() const;
Vector2f get_d(); Vector2f get_ff();
// reset_I - reset the integrator // reset the integrator
void reset_I(); void reset_I() { _integrator.zero(); };
// reset_filter - input and D term filter will be reset to the next value provided to set_input() // reset_filter - input and D term filter will be reset to the next value provided to set_input()
void reset_filter(); void reset_filter() { _reset_filter = true; }
// load gain from eeprom
void load_gains();
// save gain to eeprom // save gain to eeprom
void save_gains(); void save_gains();
@ -47,58 +49,54 @@ public:
// get accessors // get accessors
AP_Float &kP() { return _kp; } AP_Float &kP() { return _kp; }
AP_Float &kI() { return _ki; } AP_Float &kI() { return _ki; }
float imax() const { return _imax.get(); } AP_Float &kD() { return _kd; }
float filt_hz() const { return _filt_hz.get(); } AP_Float &ff() { return _kff;}
float get_filt_alpha() const { return _filt_alpha; } AP_Float &filt_E_hz() { return _filt_E_hz; }
float filt_d_hz() const { return _filt_d_hz.get(); } AP_Float &filt_D_hz() { return _filt_D_hz; }
float get_filt_alpha_D() const { return _filt_alpha_d; } float imax() const { return _kimax.get(); }
float get_filt_E_alpha() const;
float get_filt_D_alpha() const;
// set accessors // set accessors
void kP(const float v) { _kp.set(v); } void kP(float v) { _kp.set(v); }
void kI(const float v) { _ki.set(v); } void kI(float v) { _ki.set(v); }
void kD(const float v) { _kd.set(v); } void kD(float v) { _kd.set(v); }
void imax(const float v) { _imax.set(fabsf(v)); } void ff(float v) { _kff.set(v); }
void filt_hz(const float v); void imax(float v) { _kimax.set(fabsf(v)); }
void filt_d_hz(const float v); void filt_E_hz(float hz) { _filt_E_hz.set(fabsf(hz)); }
void filt_D_hz(float hz) { _filt_D_hz.set(fabsf(hz)); }
Vector2f get_integrator() const { return _integrator; } // integrator setting functions
void set_integrator(const Vector2f &i) { _integrator = i; } void set_integrator(const Vector2f& target, const Vector2f& measurement, const Vector2f& i);
void set_integrator(const Vector3f &i) { _integrator.x = i.x; _integrator.y = i.y; } void set_integrator(const Vector2f& error, const Vector2f& i);
void set_integrator(const Vector3f& i) { set_integrator(Vector2f(i.x, i.y)); }
void set_integrator(const Vector2f& i);
const AP_Logger::PID_Info& get_pid_info_x(void) const { return _pid_info_x; }
const AP_Logger::PID_Info& get_pid_info_y(void) const { return _pid_info_y; }
// parameter var table // parameter var table
static const struct AP_Param::GroupInfo var_info[]; static const struct AP_Param::GroupInfo var_info[];
protected: protected:
// set_input_filter_d - set input to PID controller
// only input to the D portion of the controller is filtered
// this should be called before any other calls to get_p, get_i or get_d
void set_input_filter_d(const Vector2f& input_delta);
// calc_filt_alpha - recalculate the input filter alpha
void calc_filt_alpha();
// calc_filt_alpha - recalculate the input filter alpha
void calc_filt_alpha_d();
// parameters // parameters
AP_Float _kp; AP_Float _kp;
AP_Float _ki; AP_Float _ki;
AP_Float _kd; AP_Float _kd;
AP_Float _imax; AP_Float _kff;
AP_Float _filt_hz; // PID Input filter frequency in Hz AP_Float _kimax;
AP_Float _filt_d_hz; // D term filter frequency in Hz AP_Float _filt_E_hz; // PID error filter frequency in Hz
AP_Float _filt_D_hz; // PID derivative filter frequency in Hz
// flags
struct ac_pid_flags {
bool _reset_filter : 1; // true when input filter should be reset during next call to set_input
} _flags;
// internal variables // internal variables
float _dt; // timestep in seconds float _dt; // timestep in seconds
float _filt_alpha; // input filter alpha Vector2f _target; // target value to enable filtering
float _filt_alpha_d; // input filter alpha Vector2f _error; // error value to enable filtering
Vector2f _derivative; // last derivative from low-pass filter
Vector2f _integrator; // integrator value Vector2f _integrator; // integrator value
Vector2f _input; // last input for derivative bool _reset_filter; // true when input filter should be reset during next call to update_all
Vector2f _derivative; // last derivative for low-pass filter
AP_Logger::PID_Info _pid_info_x;
AP_Logger::PID_Info _pid_info_y;
}; };

179
libraries/AC_PID/AC_PID_Basic.cpp Normal file
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@ -0,0 +1,179 @@
/// @file AC_PID_Basic.cpp
/// @brief Generic PID algorithm
#include <AP_Math/AP_Math.h>
#include <AP_InternalError/AP_InternalError.h>
#include "AC_PID_Basic.h"
#define AC_PID_Basic_FILT_E_HZ_DEFAULT 20.0f // default input filter frequency
#define AC_PID_Basic_FILT_E_HZ_MIN 0.01f // minimum input filter frequency
#define AC_PID_Basic_FILT_D_HZ_DEFAULT 10.0f // default input filter frequency
#define AC_PID_Basic_FILT_D_HZ_MIN 0.005f // minimum input filter frequency
const AP_Param::GroupInfo AC_PID_Basic::var_info[] = {
// @Param: P
// @DisplayName: PID Proportional Gain
// @Description: P Gain which produces an output value that is proportional to the current error value
AP_GROUPINFO("P", 0, AC_PID_Basic, _kp, 0),
// @Param: I
// @DisplayName: PID Integral Gain
// @Description: I Gain which produces an output that is proportional to both the magnitude and the duration of the error
AP_GROUPINFO("I", 1, AC_PID_Basic, _ki, 0),
// @Param: IMAX
// @DisplayName: PID Integral Maximum
// @Description: The maximum/minimum value that the I term can output
AP_GROUPINFO("IMAX", 2, AC_PID_Basic, _kimax, 0),
// @Param: FLTE
// @DisplayName: PID Error filter frequency in Hz
// @Description: Error filter frequency in Hz
// @Units: Hz
AP_GROUPINFO("FLTE", 3, AC_PID_Basic, _filt_E_hz, AC_PID_Basic_FILT_E_HZ_DEFAULT),
// @Param: D
// @DisplayName: PID Derivative Gain
// @Description: D Gain which produces an output that is proportional to the rate of change of the error
AP_GROUPINFO("D", 4, AC_PID_Basic, _kd, 0),
// @Param: FLTD
// @DisplayName: D term filter frequency in Hz
// @Description: D term filter frequency in Hz
// @Units: Hz
AP_GROUPINFO("FLTD", 5, AC_PID_Basic, _filt_D_hz, AC_PID_Basic_FILT_D_HZ_DEFAULT),
// @Param: FF
// @DisplayName: PID Feed Forward Gain
// @Description: FF Gain which produces an output that is proportional to the magnitude of the target
AP_GROUPINFO("FF", 6, AC_PID_Basic, _kff, 0),
AP_GROUPEND
};
// Constructor
AC_PID_Basic::AC_PID_Basic(float initial_p, float initial_i, float initial_d, float initial_ff, float initial_imax, float initial_filt_E_hz, float initial_filt_D_hz, float dt) :
_dt(dt)
{
// load parameter values from eeprom
AP_Param::setup_object_defaults(this, var_info);
_kp = initial_p;
_ki = initial_i;
_kd = initial_d;
_kff = initial_ff;
_kimax = fabsf(initial_imax);
filt_E_hz(initial_filt_E_hz);
filt_D_hz(initial_filt_D_hz);
// reset input filter to first value received
_reset_filter = true;
}
float AC_PID_Basic::update_all(float target, float measurement, bool limit)
{
return update_all(target, measurement, (limit && is_negative(_integrator)), (limit && is_positive(_integrator)));
}
// update_all - set target and measured inputs to PID controller and calculate outputs
// target and error are filtered
// the derivative is then calculated and filtered
// the integral is then updated based on the setting of the limit flag
float AC_PID_Basic::update_all(float target, float measurement, bool limit_neg, bool limit_pos)
{
// don't process inf or NaN
if (!isfinite(target) || isnan(target) ||
!isfinite(measurement) || isnan(measurement)) {
INTERNAL_ERROR(AP_InternalError::error_t::invalid_arg_or_result);
return 0.0f;
}
_target = target;
// reset input filter to value received
if (_reset_filter) {
_reset_filter = false;
_error = _target - measurement;
_derivative = 0.0f;
} else {
float error_last = _error;
_error += get_filt_E_alpha() * ((_target - measurement) - _error);
// calculate and filter derivative
if (is_positive(_dt)) {
float derivative = (_error - error_last) / _dt;
_derivative += get_filt_D_alpha() * (derivative - _derivative);
}
}
// update I term
update_i(limit_neg, limit_pos);
const float P_out = _error * _kp;
const float D_out = _derivative * _kd;
_pid_info.target = _target;
_pid_info.actual = measurement;
_pid_info.error = _error;
_pid_info.P = _error * _kp;
_pid_info.I = _integrator;
_pid_info.D = _derivative * _kd;
_pid_info.FF = _target * _kff;
return P_out + _integrator + D_out + _target * _kff;
}
// update_i - update the integral
// if limit_neg is true, the integral can only increase
// if limit_pos is true, the integral can only decrease
void AC_PID_Basic::update_i(bool limit_neg, bool limit_pos)
{
if (!is_zero(_ki)) {
// Ensure that integrator can only be reduced if the output is saturated
if (!((limit_neg && is_negative(_error)) || (limit_pos && is_positive(_error)))) {
_integrator += ((float)_error * _ki) * _dt;
_integrator = constrain_float(_integrator, -_kimax, _kimax);
}
} else {
_integrator = 0.0f;
}
}
// save_gains - save gains to eeprom
void AC_PID_Basic::save_gains()
{
_kp.save();
_ki.save();
_kd.save();
_kff.save();
_kimax.save();
_filt_E_hz.save();
_filt_D_hz.save();
}
// get_filt_T_alpha - get the target filter alpha
float AC_PID_Basic::get_filt_E_alpha() const
{
return calc_lowpass_alpha_dt(_dt, _filt_E_hz);
}
// get_filt_D_alpha - get the derivative filter alpha
float AC_PID_Basic::get_filt_D_alpha() const
{
return calc_lowpass_alpha_dt(_dt, _filt_D_hz);
}
void AC_PID_Basic::set_integrator(float target, float measurement, float i)
{
set_integrator(target - measurement, i);
}
void AC_PID_Basic::set_integrator(float error, float i)
{
set_integrator(i - error * _kp);
}
void AC_PID_Basic::set_integrator(float i)
{
_integrator = constrain_float(i, -_kimax, _kimax);
}

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#pragma once
/// @file AC_PID_Basic.h
/// @brief Generic PID algorithm, with EEPROM-backed storage of constants.
#include <AP_Common/AP_Common.h>
#include <AP_Param/AP_Param.h>
#include <AP_Logger/AP_Logger.h>
/// @class AC_PID_Basic
/// @brief Copter PID control class
class AC_PID_Basic {
public:
// Constructor for PID
AC_PID_Basic(float initial_p, float initial_i, float initial_d, float initial_ff, float initial_imax, float initial_filt_E_hz, float initial_filt_D_hz, float dt);
// set time step in seconds
void set_dt(float dt) { _dt = dt; }
// set target and measured inputs to PID controller and calculate outputs
// target and error are filtered
// the derivative is then calculated and filtered
// the integral is then updated based on the setting of the limit flag
float update_all(float target, float measurement, bool limit = false) WARN_IF_UNUSED;
float update_all(float target, float measurement, bool limit_neg, bool limit_pos) WARN_IF_UNUSED;
// update the integral
// if the limit flags are set the integral is only allowed to shrink
void update_i(bool limit_neg, bool limit_pos);
// get results from pid controller
float get_p() const WARN_IF_UNUSED { return _error * _kp; }
float get_i() const WARN_IF_UNUSED { return _integrator; }
float get_d() const WARN_IF_UNUSED { return _derivative * _kd; }
float get_ff() const WARN_IF_UNUSED { return _target * _kff; }
// reset the integrator
void reset_I() { _integrator = 0.0f; }
// input and D term filter will be reset to the next value provided to set_input()
void reset_filter() { _reset_filter = true; }
// save gain to eeprom
void save_gains();
// get accessors
AP_Float &kP() WARN_IF_UNUSED { return _kp; }
AP_Float &kI() WARN_IF_UNUSED { return _ki; }
AP_Float &kD() WARN_IF_UNUSED { return _kd; }
AP_Float &ff() WARN_IF_UNUSED { return _kff;}
AP_Float &filt_E_hz() WARN_IF_UNUSED { return _filt_E_hz; }
AP_Float &filt_D_hz() WARN_IF_UNUSED { return _filt_D_hz; }
float imax() const WARN_IF_UNUSED { return _kimax.get(); }
float get_filt_E_alpha() const WARN_IF_UNUSED;
float get_filt_D_alpha() const WARN_IF_UNUSED;
// set accessors
void kP(float v) { _kp.set(v); }
void kI(float v) { _ki.set(v); }
void kD(float v) { _kd.set(v); }
void ff(float v) { _kff.set(v); }
void imax(float v) { _kimax.set(fabsf(v)); }
void filt_E_hz(float hz) { _filt_E_hz.set(fabsf(hz)); }
void filt_D_hz(float hz) { _filt_D_hz.set(fabsf(hz)); }
// integrator setting functions
void set_integrator(float target, float measurement, float i);
void set_integrator(float error, float i);
void set_integrator(float i);
const AP_Logger::PID_Info& get_pid_info(void) const WARN_IF_UNUSED { return _pid_info; }
// parameter var table
static const struct AP_Param::GroupInfo var_info[];
protected:
// parameters
AP_Float _kp;
AP_Float _ki;
AP_Float _kd;
AP_Float _kff;
AP_Float _kimax;
AP_Float _filt_E_hz; // PID error filter frequency in Hz
AP_Float _filt_D_hz; // PID derivative filter frequency in Hz
// internal variables
float _dt; // timestep in seconds
float _target; // target value to enable filtering
float _error; // error value to enable filtering
float _derivative; // last derivative for low-pass filter
float _integrator; // integrator value
bool _reset_filter; // true when input filter should be reset during next call to set_input
AP_Logger::PID_Info _pid_info;
};

14
libraries/AC_PID/AC_PI_2D.cpp
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@ -1,27 +1,27 @@
/// @file AC_PI_2D.cpp /// @file AC_PI_2D.cpp
/// @brief Generic PID algorithm /// @brief 2-axis PI controller
#include <AP_Math/AP_Math.h> #include <AP_Math/AP_Math.h>
#include "AC_PI_2D.h" #include "AC_PI_2D.h"
const AP_Param::GroupInfo AC_PI_2D::var_info[] = { const AP_Param::GroupInfo AC_PI_2D::var_info[] = {
// @Param: P // @Param: P
// @DisplayName: PID Proportional Gain // @DisplayName: PI Proportional Gain
// @Description: P Gain which produces an output value that is proportional to the current error value // @Description: P Gain which produces an output value that is proportional to the current error value
AP_GROUPINFO("P", 0, AC_PI_2D, _kp, 0), AP_GROUPINFO("P", 0, AC_PI_2D, _kp, 0),
// @Param: I // @Param: I
// @DisplayName: PID Integral Gain // @DisplayName: PI Integral Gain
// @Description: I Gain which produces an output that is proportional to both the magnitude and the duration of the error // @Description: I Gain which produces an output that is proportional to both the magnitude and the duration of the error
AP_GROUPINFO("I", 1, AC_PI_2D, _ki, 0), AP_GROUPINFO("I", 1, AC_PI_2D, _ki, 0),
// @Param: IMAX // @Param: IMAX
// @DisplayName: PID Integral Maximum // @DisplayName: PI Integral Maximum
// @Description: The maximum/minimum value that the I term can output // @Description: The maximum/minimum value that the I term can output
AP_GROUPINFO("IMAX", 2, AC_PI_2D, _imax, 0), AP_GROUPINFO("IMAX", 2, AC_PI_2D, _imax, 0),
// @Param: FILT_HZ // @Param: FILT_HZ
// @DisplayName: PID Input filter frequency in Hz // @DisplayName: PI Input filter frequency in Hz
// @Description: Input filter frequency in Hz // @Description: Input filter frequency in Hz
// @Units: Hz // @Units: Hz
AP_GROUPINFO("FILT_HZ", 3, AC_PI_2D, _filt_hz, AC_PI_2D_FILT_HZ_DEFAULT), AP_GROUPINFO("FILT_HZ", 3, AC_PI_2D, _filt_hz, AC_PI_2D_FILT_HZ_DEFAULT),
@ -101,7 +101,7 @@ Vector2f AC_PI_2D::get_i()
} }
return _integrator; return _integrator;
} }
return Vector2f(); return Vector2f{};
} }
// get_i_shrink - get_i but do not allow integrator to grow in length (it may shrink) // get_i_shrink - get_i but do not allow integrator to grow in length (it may shrink)
@ -116,7 +116,7 @@ Vector2f AC_PI_2D::get_i_shrink()
} }
return _integrator; return _integrator;
} }
return Vector2f(); return Vector2f{};
} }
Vector2f AC_PI_2D::get_pi() Vector2f AC_PI_2D::get_pi()

12
libraries/AC_PID/AC_PI_2D.h
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@ -1,7 +1,7 @@
#pragma once #pragma once
/// @file AC_PI_2D.h /// @file AC_PI_2D.h
/// @brief Generic PID algorithm, with EEPROM-backed storage of constants. /// @brief 2-axis PI controller with EEPROM-backed storage of constants.
#include <AP_Common/AP_Common.h> #include <AP_Common/AP_Common.h>
#include <AP_Param/AP_Param.h> #include <AP_Param/AP_Param.h>
@ -12,18 +12,18 @@
#define AC_PI_2D_FILT_HZ_MIN 0.01f // minimum input filter frequency #define AC_PI_2D_FILT_HZ_MIN 0.01f // minimum input filter frequency
/// @class AC_PI_2D /// @class AC_PI_2D
/// @brief Copter PID control class /// @brief 2-axis PI controller
class AC_PI_2D { class AC_PI_2D {
public: public:
// Constructor for PID // constructor
AC_PI_2D(float initial_p, float initial_i, float initial_imax, float initial_filt_hz, float dt); AC_PI_2D(float initial_p, float initial_i, float initial_imax, float initial_filt_hz, float dt);
// set time step in seconds // set time step in seconds
void set_dt(float dt); void set_dt(float dt);
// set_input - set input to PID controller // set_input - set input to PI controller
// input is filtered before the PID controllers are run // input is filtered before the PI controllers are run
// this should be called before any other calls to get_p, get_i or get_d // this should be called before any other calls to get_p, get_i or get_d
void set_input(const Vector2f &input); void set_input(const Vector2f &input);
void set_input(const Vector3f &input) { set_input(Vector2f(input.x, input.y)); } void set_input(const Vector3f &input) { set_input(Vector2f(input.x, input.y)); }
@ -78,7 +78,7 @@ private:
AP_Float _kp; AP_Float _kp;
AP_Float _ki; AP_Float _ki;
AP_Float _imax; AP_Float _imax;
AP_Float _filt_hz; // PID Input filter frequency in Hz AP_Float _filt_hz; // PI Input filter frequency in Hz
// flags // flags
struct ac_pid_flags { struct ac_pid_flags {

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/// @file AC_P_1D.cpp
/// @brief Generic P algorithm
#include <AP_Math/AP_Math.h>
#include "AC_P_1D.h"
const AP_Param::GroupInfo AC_P_1D::var_info[] = {
// @Param: P
// @DisplayName: P Proportional Gain
// @Description: P Gain which produces an output value that is proportional to the current error value
AP_GROUPINFO("P", 0, AC_P_1D, _kp, 0),
AP_GROUPEND
};
// Constructor
AC_P_1D::AC_P_1D(float initial_p, float dt) :
_dt(dt)
{
// load parameter values from eeprom
AP_Param::setup_object_defaults(this, var_info);
_kp = initial_p;
_lim_D_Out = 10.0f; // maximum first differential of output
}
// update_all - set target and measured inputs to P controller and calculate outputs
// target and measurement are filtered
// if measurement is further than error_min or error_max (see set_limits_error method)
// the target is moved closer to the measurement and limit_min or limit_max will be set true
float AC_P_1D::update_all(float &target, float measurement, bool &limit_min, bool &limit_max)
{
limit_min = false;
limit_max = false;
// calculate distance _error
float error = target - measurement;
if (error < _lim_err_min) {
error = _lim_err_min;
target = measurement + error;
limit_min = true;
} else if (error > _lim_err_max) {
error = _lim_err_max;
target = measurement + error;
limit_max = true;
}
// ToDo: Replace sqrt_controller with optimal acceleration and jerk limited curve
// MIN(_Dxy_max, _D2xy_max / _kxy_P) limits the max accel to the point where max jerk is exceeded
return sqrt_controller(error, _kp, _lim_D_Out, _dt);
}
// set limits on error, output and output from D term
// in normal use the lim_err_min and lim_out_min will be negative
// when using for a position controller, lim_err will be position error, lim_out will be correction velocity, lim_D will be acceleration, lim_D2 will be jerk
void AC_P_1D::set_limits_error(float lim_err_min, float lim_err_max, float lim_out_min, float lim_out_max, float lim_D_Out, float lim_D2_Out)
{
_lim_D_Out = lim_D_Out;
if (is_positive(lim_D2_Out)) {
// limit the first derivative so as not to exceed the second derivative
_lim_D_Out = MIN(_lim_D_Out, lim_D2_Out / _kp);
}
_lim_err_min = MAX(inv_sqrt_controller(lim_out_min, _kp, _lim_D_Out), lim_err_min);
_lim_err_max = MAX(inv_sqrt_controller(lim_out_max, _kp, _lim_D_Out), lim_err_max);
}

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#pragma once
/// @file AC_P_1D.h
/// @brief Generic P controller, with EEPROM-backed storage of constants.
#include <AP_Common/AP_Common.h>
#include <AP_Param/AP_Param.h>
/// @class AC_P_1D
/// @brief Object managing one P controller
class AC_P_1D {
public:
// constructor
AC_P_1D(float initial_p, float dt);
// set time step in seconds
void set_dt(float dt) { _dt = dt; }
// update_all - set target and measured inputs to P controller and calculate outputs
// target and measurement are filtered
// if measurement is further than error_min or error_max (see set_limits_error method)
// the target is moved closer to the measurement and limit_min or limit_max will be set true
float update_all(float &target, float measurement, bool &limit_min, bool &limit_max) WARN_IF_UNUSED;
// save gain to eeprom
void save_gains() { _kp.save(); }
// set limits on error, output and output from D term
void set_limits_error(float error_min, float error_max, float output_min, float output_max, float D_Out_max = 0.0f, float D2_Out_max = 0.0f);
// accessors
AP_Float &kP() WARN_IF_UNUSED { return _kp; }
const AP_Float &kP() const WARN_IF_UNUSED { return _kp; }
void kP(float v) { _kp.set(v); }
// parameter var table
static const struct AP_Param::GroupInfo var_info[];
private:
// parameters
AP_Float _kp;
// internal variables
float _dt; // time step in seconds
float _lim_err_min; // error limit in negative direction
float _lim_err_max; // error limit in positive direction
float _lim_D_Out; // maximum first differential of output
};

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/// @file AC_P_2D.cpp
/// @brief 2-axis P controller
#include <AP_Math/AP_Math.h>
#include "AC_P_2D.h"
const AP_Param::GroupInfo AC_P_2D::var_info[] = {
// @Param: P
// @DisplayName: Proportional Gain
// @Description: P Gain which produces an output value that is proportional to the current error value
AP_GROUPINFO("P", 0, AC_P_2D, _kp, 0),
AP_GROUPEND
};
// Constructor
AC_P_2D::AC_P_2D(float initial_p, float dt) :
_dt(dt)
{
// load parameter values from eeprom
AP_Param::setup_object_defaults(this, var_info);
_kp = initial_p;
}
// set target and measured inputs to P controller and calculate outputs
Vector2f AC_P_2D::update_all(float &target_x, float &target_y, const Vector2f &measurement, float error_max, float D2_max)
{
// calculate distance _error
Vector2f error = Vector2f(target_x, target_y) - measurement;
// Constrain _error and target position
// Constrain the maximum length of _vel_target to the maximum position correction velocity
if (error.limit_length(error_max)) {
target_x = measurement.x + error.x;
target_y = measurement.y + error.y;
}
// MIN(_Dmax, _D2max / _kp) limits the max accel to the point where max jerk is exceeded
// return sqrt_controller(Vector2f(_error.x, _error.y), _kp, MIN(_D_max, _D2_max / _kp), _dt);
return sqrt_controller(error, _kp, D2_max, _dt);
}

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@ -0,0 +1,45 @@
#pragma once
/// @file AC_P_2D.h
/// @brief 2-axis P controller with EEPROM-backed storage of constants.
#include <AP_Common/AP_Common.h>
#include <AP_Param/AP_Param.h>
/// @class AC_P_2D
/// @brief 2-axis P controller
class AC_P_2D {
public:
// constructor
AC_P_2D(float initial_p, float dt);
// set time step in seconds
void set_dt(float dt) { _dt = dt; }
// set target and measured inputs to P controller and calculate outputs
Vector2f update_all(float &target_x, float &target_y, const Vector2f &measurement, float error_max, float D2_max) WARN_IF_UNUSED;
// set target and measured inputs to P controller and calculate outputs
// measurement is provided as 3-axis vector but only x and y are used
Vector2f update_all(float &target_x, float &target_y, const Vector3f &measurement, float error_max, float D2_max) WARN_IF_UNUSED {
return update_all(target_x, target_y, Vector2f(measurement.x, measurement.y), error_max, D2_max);
}
// get accessors
AP_Float &kP() WARN_IF_UNUSED { return _kp; }
const AP_Float &kP() const WARN_IF_UNUSED { return _kp; }
// set accessor
void kP(float v) { _kp.set(v); }
// parameter var table
static const struct AP_Param::GroupInfo var_info[];
private:
// parameters
AP_Float _kp;
// internal variables
float _dt; // time step in seconds
};