c7c675852e
Instead of using fixed constants, set them by the following formula from the current sync to allow good performance of the servo even when the sync interval changes in runtime and to avoid instability. kp = min(kp_scale * sync^kp_exponent, kp_norm_max / sync) ki = min(ki_scale * sync^ki_exponent, ki_norm_max / sync) The scale, exponent and norm_max constants are configurable. The defaults are chosen so there is no change to the previous default constants of the servo with one second sync interval. The automatic adjustment can be disabled by setting the pi_proportional_const and pi_integral_const options to a non-zero value, but stability of the servo is always enforced. Signed-off-by: Miroslav Lichvar <mlichvar@redhat.com>
107 lines
3.5 KiB
C
107 lines
3.5 KiB
C
/**
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* @file pi.h
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* @note Copyright (C) 2011 Richard Cochran <richardcochran@gmail.com>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (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,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU 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 along
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* with this program; if not, write to the Free Software Foundation, Inc.,
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* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
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*/
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#ifndef HAVE_PI_H
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#define HAVE_PI_H
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#include "servo.h"
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/**
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* When set to a non-zero value, this variable determines the
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* proportional constant for the PI controller.
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*/
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extern double configured_pi_kp;
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/**
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* When set to a non-zero value, this variable determines the
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* integral constant for the PI controller.
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*/
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extern double configured_pi_ki;
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/**
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* When set to a non-zero value, this variable determines the scale in the
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* formula used to set the proportional constant of the PI controller from the
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* sync interval.
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* kp = min(kp_scale * sync^kp_exponent, kp_norm_max / sync)
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*/
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extern double configured_pi_kp_scale;
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/**
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* This variable determines the exponent in the formula used to set the
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* proportional constant of the PI controller from the sync interval.
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* kp = min(kp_scale * sync^kp_exponent, kp_norm_max / sync)
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*/
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extern double configured_pi_kp_exponent;
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/**
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* This variable determines the normalized maximum in the formula used to set
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* the proportional constant of the PI controller from the sync interval.
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* kp = min(kp_scale * sync^kp_exponent, kp_norm_max / sync)
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*/
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extern double configured_pi_kp_norm_max;
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/**
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* When set to a non-zero value, this variable determines the scale in the
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* formula used to set the integral constant of the PI controller from the
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* sync interval.
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* ki = min(ki_scale * sync^ki_exponent, ki_norm_max / sync)
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*/
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extern double configured_pi_ki_scale;
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/**
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* This variable determines the exponent in the formula used to set the
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* integral constant of the PI controller from the sync interval.
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* ki = min(ki_scale * sync^ki_exponent, ki_norm_max / sync)
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*/
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extern double configured_pi_ki_exponent;
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/**
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* This variable determines the normalized maximum in the formula used to set
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* the integral constant of the PI controller from the sync interval.
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* ki = min(ki_scale * sync^ki_exponent, ki_norm_max / sync)
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*/
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extern double configured_pi_ki_norm_max;
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/**
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* When set to a non-zero value, this variable controls the maximum allowed
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* offset before a clock jump occurs instead of the default clock-slewing
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* mechanism.
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*
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* Note that this variable is measured in seconds, and allows fractional values.
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*/
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extern double configured_pi_offset;
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/**
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* When set to zero, the clock is not stepped on start. When set to a non-zero
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* value, the value bahaves as a threshold and the clock is stepped on start if
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* the offset is bigger than the threshold.
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*
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* Note that this variable is measured in seconds, and allows fractional values.
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*/
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extern double configured_pi_f_offset;
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/**
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* When set to a non-zero value, this variable sets an additional limit for
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* the frequency adjustment of the clock. It's in ppb.
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*/
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extern int configured_pi_max_freq;
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struct servo *pi_servo_create(int fadj, int max_ppb, int sw_ts);
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#endif
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