2018-02-23 22:51:51 +00:00
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/*-
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* SPDX-License-Identifier: BSD-2-Clause-FreeBSD
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*
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* Copyright (c) 2017, Jeffrey Roberson <jeff@freebsd.org>
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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2018-05-15 00:50:09 +00:00
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* notice, this list of conditions and the following disclaimer.
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2018-02-23 22:51:51 +00:00
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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2018-05-15 00:50:09 +00:00
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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2018-02-23 22:51:51 +00:00
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*/
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#include <sys/cdefs.h>
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__FBSDID("$FreeBSD$");
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#include <sys/param.h>
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#include <sys/kernel.h>
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#include <sys/systm.h>
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#include <sys/sysctl.h>
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#include <sys/pidctrl.h>
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void
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pidctrl_init(struct pidctrl *pc, int interval, int setpoint, int bound,
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int Kpd, int Kid, int Kdd)
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{
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bzero(pc, sizeof(*pc));
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pc->pc_setpoint = setpoint;
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pc->pc_interval = interval;
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pc->pc_bound = bound * setpoint * Kid;
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pc->pc_Kpd = Kpd;
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pc->pc_Kid = Kid;
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pc->pc_Kdd = Kdd;
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}
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void
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pidctrl_init_sysctl(struct pidctrl *pc, struct sysctl_oid_list *parent)
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{
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SYSCTL_ADD_INT(NULL, parent, OID_AUTO, "error", CTLFLAG_RD,
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&pc->pc_error, 0, "Current difference from setpoint value (P)");
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SYSCTL_ADD_INT(NULL, parent, OID_AUTO, "olderror", CTLFLAG_RD,
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&pc->pc_olderror, 0, "Error value from last interval");
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SYSCTL_ADD_INT(NULL, parent, OID_AUTO, "integral", CTLFLAG_RD,
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&pc->pc_integral, 0, "Accumulated error integral (I)");
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SYSCTL_ADD_INT(NULL, parent, OID_AUTO, "derivative",
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CTLFLAG_RD, &pc->pc_derivative, 0, "Error derivative (I)");
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SYSCTL_ADD_INT(NULL, parent, OID_AUTO, "input", CTLFLAG_RD,
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&pc->pc_input, 0, "Last controller process variable input");
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SYSCTL_ADD_INT(NULL, parent, OID_AUTO, "output", CTLFLAG_RD,
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&pc->pc_output, 0, "Last controller output");
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SYSCTL_ADD_INT(NULL, parent, OID_AUTO, "ticks", CTLFLAG_RD,
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&pc->pc_ticks, 0, "Last controler runtime");
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SYSCTL_ADD_INT(NULL, parent, OID_AUTO, "setpoint", CTLFLAG_RW,
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&pc->pc_setpoint, 0, "Desired level for process variable");
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SYSCTL_ADD_INT(NULL, parent, OID_AUTO, "interval", CTLFLAG_RD,
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&pc->pc_interval, 0, "Interval between calculations (ticks)");
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SYSCTL_ADD_INT(NULL, parent, OID_AUTO, "bound", CTLFLAG_RW,
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&pc->pc_bound, 0, "Integral wind-up limit");
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SYSCTL_ADD_INT(NULL, parent, OID_AUTO, "kpd", CTLFLAG_RW,
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&pc->pc_Kpd, 0, "Inverse of proportional gain");
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SYSCTL_ADD_INT(NULL, parent, OID_AUTO, "kid", CTLFLAG_RW,
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&pc->pc_Kid, 0, "Inverse of integral gain");
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SYSCTL_ADD_INT(NULL, parent, OID_AUTO, "kdd", CTLFLAG_RW,
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&pc->pc_Kdd, 0, "Inverse of derivative gain");
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}
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int
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pidctrl_classic(struct pidctrl *pc, int input)
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{
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int output, error;
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int Kpd, Kid, Kdd;
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error = pc->pc_setpoint - input;
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pc->pc_ticks = ticks;
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pc->pc_olderror = pc->pc_error;
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/* Fetch gains and prevent divide by zero. */
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Kpd = MAX(pc->pc_Kpd, 1);
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Kid = MAX(pc->pc_Kid, 1);
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Kdd = MAX(pc->pc_Kdd, 1);
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/* Compute P (proportional error), I (integral), D (derivative) */
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pc->pc_error = error;
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pc->pc_integral =
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MAX(MIN(pc->pc_integral + error, pc->pc_bound), -pc->pc_bound);
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pc->pc_derivative = error - pc->pc_olderror;
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/* Divide by inverse gain values to produce output. */
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output = ((pc->pc_error / pc->pc_Kpd) +
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(pc->pc_integral / pc->pc_Kid)) +
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(pc->pc_derivative / pc->pc_Kdd);
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/* Save for sysctl. */
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pc->pc_output = output;
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pc->pc_input = input;
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return output;
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}
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int
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pidctrl_daemon(struct pidctrl *pc, int input)
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{
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int output, error;
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int Kpd, Kid, Kdd;
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error = pc->pc_setpoint - input;
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/*
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* When ticks expired we reset our variables and start a new
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* interval. If we're called multiple times during one interval
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* we attempt to report a target as if the entire error came at
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* the interval boundary.
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*/
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if ((u_int)(ticks - pc->pc_ticks) >= pc->pc_interval) {
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pc->pc_ticks = ticks;
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pc->pc_olderror = pc->pc_error;
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pc->pc_output = pc->pc_error = 0;
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} else {
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error = MAX(error + pc->pc_error, 0);
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}
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/* Fetch gains and prevent divide by zero. */
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Kpd = MAX(pc->pc_Kpd, 1);
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Kid = MAX(pc->pc_Kid, 1);
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Kdd = MAX(pc->pc_Kdd, 1);
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/* Compute P (proportional error), I (integral), D (derivative) */
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pc->pc_error = error;
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pc->pc_integral =
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MAX(MIN(pc->pc_integral + error, pc->pc_bound), 0);
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pc->pc_derivative = error - pc->pc_olderror;
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/* Divide by inverse gain values to produce output. */
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output = ((error / pc->pc_Kpd) +
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(pc->pc_integral / pc->pc_Kid)) +
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(pc->pc_derivative / pc->pc_Kdd);
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output = MAX(output - pc->pc_output, 0);
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pc->pc_output += output;
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pc->pc_input = input;
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return output;
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}
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