Precision PI Controller

Precision PI Controller. More...

Data Structures
struct	precision_pi
	State of an independent proportional-integral controller. More...

Functions
void	precision_pi_init (struct precision_pi *pi, double kp, double ki)
	Initialize a PI controller.
void	precision_pi_reset (struct precision_pi *pi)
	Reset the accumulated integral term.
void	precision_pi_set_limits (struct precision_pi *pi, double integral_limit, double output_limit)
	Set the limits of a PI controller.
double	precision_pi_update (struct precision_pi *pi, double error)
	Update a PI controller from an error sample.
double	precision_pi_update_interval (struct precision_pi *pi, double error, double interval)
	Update a PI controller from an error sample taken after an interval.

Detailed Description

Precision PI Controller.

Since

4.5

Version

0.2.0

Function Documentation

precision_pi_init()

void precision_pi_init	(	struct precision_pi *	pi,
		double	kp,
		double	ki )

#include <zephyr/precision_timing/precision_pi.h>

Initialize a PI controller.

Parameters

pi	Controller instance.
kp	Proportional gain.
ki	Integral gain.

precision_pi_reset()

void precision_pi_reset

(

struct precision_pi *

pi

)

#include <zephyr/precision_timing/precision_pi.h>

Reset the accumulated integral term.

The configured gains are preserved.

Parameters

pi	Controller instance.

precision_pi_set_limits()

void precision_pi_set_limits	(	struct precision_pi *	pi,
		double	integral_limit,
		double	output_limit )

#include <zephyr/precision_timing/precision_pi.h>

Set the limits of a PI controller.

The integral term is held within +-integral_limit, so it cannot wind up while a large error lasts. The output is held within +-output_limit, and while the output is at that limit the integral term does not move further towards it. A limit of 0 disables it, which is the state after precision_pi_init().

Parameters

pi	Controller instance.
integral_limit	Largest magnitude of the integral term, 0 for no limit.
output_limit	Largest magnitude of the output, 0 for no limit.

precision_pi_update()

double precision_pi_update	(	struct precision_pi *	pi,
		double	error )

#include <zephyr/precision_timing/precision_pi.h>

Update a PI controller from an error sample.

Same as precision_pi_update_interval() with an interval of 1.

Parameters

pi	Controller instance.
error	Current control error.

Returns

Controller output.

precision_pi_update_interval()

double precision_pi_update_interval	(	struct precision_pi *	pi,
		double	error,
		double	interval )

#include <zephyr/precision_timing/precision_pi.h>

Update a PI controller from an error sample taken after an interval.

The gains are given for an interval of 1 and are divided by interval. When the plant integrates the output over the interval, as a clock does with a rate correction, the loop gains per sample are then kp and ki for any interval, so the loop keeps its stability and damping when the sample rate changes.

Parameters

pi	Controller instance.
error	Current control error.
interval	Time since the previous sample, in the unit the gains are given for. Must be greater than 0.

Returns

Controller output.