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klipper/klippy/chelper/kin_shaper.c

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// Kinematic input shapers to minimize motion vibrations in XY plane
//
// Copyright (C) 2019-2020 Kevin O'Connor <kevin@koconnor.net>
// Copyright (C) 2020 Dmitry Butyugin <dmbutyugin@google.com>
//
// This file may be distributed under the terms of the GNU GPLv3 license.
#include <math.h> // sqrt, exp
#include <stddef.h> // offsetof
#include <stdlib.h> // malloc
#include <string.h> // memset
#include "compiler.h" // __visible
#include "itersolve.h" // struct stepper_kinematics
#include "trapq.h" // struct move
/****************************************************************
* Generic position calculation via shaper convolution
****************************************************************/
static inline double
get_axis_position(struct move *m, int axis, double move_time)
{
double axis_r = m->axes_r.axis[axis - 'x'];
double start_pos = m->start_pos.axis[axis - 'x'];
double move_dist = move_get_distance(m, move_time);
return start_pos + axis_r * move_dist;
}
static inline double
get_axis_position_across_moves(struct move *m, int axis, double time)
{
while (likely(time < 0.)) {
m = list_prev_entry(m, node);
time += m->move_t;
}
while (likely(time > m->move_t)) {
time -= m->move_t;
m = list_next_entry(m, node);
}
return get_axis_position(m, axis, time);
}
struct shaper_pulse {
double t, a;
};
// Calculate the position from the convolution of the shaper with input signal
static inline double
calc_position(struct move *m, int axis, double move_time
, struct shaper_pulse *pulses, int n)
{
double res = 0.;
int i;
for (i = 0; i < n; ++i)
res += pulses[i].a * get_axis_position_across_moves(
m, axis, move_time + pulses[i].t);
return res;
}
/****************************************************************
* Shaper-specific initialization
****************************************************************/
#define EI_SHAPER_VIB_TOL 0.05
enum INPUT_SHAPER_TYPE {
INPUT_SHAPER_ZV = 0,
INPUT_SHAPER_ZVD = 1,
INPUT_SHAPER_MZV = 2,
INPUT_SHAPER_EI = 3,
INPUT_SHAPER_2HUMP_EI = 4,
INPUT_SHAPER_3HUMP_EI = 5,
};
struct input_shaper {
struct stepper_kinematics sk;
struct stepper_kinematics *orig_sk;
struct move m;
struct shaper_pulse *x_pulses, *y_pulses;
int x_n, y_n;
};
typedef void (*is_init_shaper_callback)(double shaper_freq
, double damping_ratio
, struct shaper_pulse **pulses, int *n);
static inline double
calc_ZV_K(double damping_ratio)
{
if (likely(!damping_ratio))
return 1.;
return exp(-damping_ratio * M_PI / sqrt(1. - damping_ratio*damping_ratio));
}
static inline double
calc_half_period(double shaper_freq, double damping_ratio)
{
return .5 / (shaper_freq * sqrt(1. - damping_ratio*damping_ratio));
}
static void
init_shaper_zv(double shaper_freq, double damping_ratio
, struct shaper_pulse **pulses, int *n)
{
*n = 2;
*pulses = malloc(*n * sizeof(struct shaper_pulse));
double half_period = calc_half_period(shaper_freq, damping_ratio);
double K = calc_ZV_K(damping_ratio);
double inv_D = 1. / (1. + K);
(*pulses)[0].t = -half_period;
(*pulses)[1].t = 0.;
(*pulses)[0].a = K * inv_D;
(*pulses)[1].a = inv_D;
}
static void
init_shaper_zvd(double shaper_freq, double damping_ratio
, struct shaper_pulse **pulses, int *n)
{
*n = 3;
*pulses = malloc(*n * sizeof(struct shaper_pulse));
double half_period = calc_half_period(shaper_freq, damping_ratio);
double K = calc_ZV_K(damping_ratio);
double K2 = K * K;
double inv_D = 1. / (K2 + 2. * K + 1.);
(*pulses)[0].t = -2. * half_period;
(*pulses)[1].t = -half_period;
(*pulses)[2].t = 0.;
(*pulses)[0].a = K2 * inv_D;
(*pulses)[1].a = 2. * K * inv_D;
(*pulses)[2].a = inv_D;
}
static void
init_shaper_mzv(double shaper_freq, double damping_ratio
, struct shaper_pulse **pulses, int *n)
{
*n = 3;
*pulses = malloc(*n * sizeof(struct shaper_pulse));
double half_period = calc_half_period(shaper_freq, damping_ratio);
double K = exp(-.75 * damping_ratio * M_PI
/ sqrt(1. - damping_ratio*damping_ratio));
double a1 = 1. - 1. / sqrt(2.);
double a2 = (sqrt(2.) - 1.) * K;
double a3 = a1 * K * K;
double inv_D = 1. / (a1 + a2 + a3);
(*pulses)[0].t = -1.5 * half_period;
(*pulses)[1].t = -.75 * half_period;
(*pulses)[2].t = 0.;
(*pulses)[0].a = a3 * inv_D;
(*pulses)[1].a = a2 * inv_D;
(*pulses)[2].a = a1 * inv_D;
}
static void
init_shaper_ei(double shaper_freq, double damping_ratio
, struct shaper_pulse **pulses, int *n)
{
*n = 3;
*pulses = malloc(*n * sizeof(struct shaper_pulse));
double half_period = calc_half_period(shaper_freq, damping_ratio);
double K = calc_ZV_K(damping_ratio);
double a1 = .25 * (1. + EI_SHAPER_VIB_TOL);
double a2 = .5 * (1. - EI_SHAPER_VIB_TOL) * K;
double a3 = a1 * K * K;
double inv_D = 1. / (a1 + a2 + a3);
(*pulses)[0].t = -2. * half_period;
(*pulses)[1].t = -half_period;
(*pulses)[2].t = 0.;
(*pulses)[0].a = a3 * inv_D;
(*pulses)[1].a = a2 * inv_D;
(*pulses)[2].a = a1 * inv_D;
}
static void
init_shaper_2hump_ei(double shaper_freq, double damping_ratio
, struct shaper_pulse **pulses, int *n)
{
*n = 4;
*pulses = malloc(*n * sizeof(struct shaper_pulse));
double half_period = calc_half_period(shaper_freq, damping_ratio);
double K = calc_ZV_K(damping_ratio);
double V2 = EI_SHAPER_VIB_TOL * EI_SHAPER_VIB_TOL;
double X = pow(V2 * (sqrt(1. - V2) + 1.), 1./3.);
double a1 = (3.*X*X + 2.*X + 3.*V2) / (16.*X);
double a2 = (.5 - a1) * K;
double a3 = a2 * K;
double a4 = a1 * K * K * K;
double inv_D = 1. / (a1 + a2 + a3 + a4);
(*pulses)[0].t = -3. * half_period;
(*pulses)[1].t = -2. * half_period;
(*pulses)[2].t = -half_period;
(*pulses)[3].t = 0.;
(*pulses)[0].a = a4 * inv_D;
(*pulses)[1].a = a3 * inv_D;
(*pulses)[2].a = a2 * inv_D;
(*pulses)[3].a = a1 * inv_D;
}
static void
init_shaper_3hump_ei(double shaper_freq, double damping_ratio
, struct shaper_pulse **pulses, int *n)
{
*n = 5;
*pulses = malloc(*n * sizeof(struct shaper_pulse));
double half_period = calc_half_period(shaper_freq, damping_ratio);
double K = calc_ZV_K(damping_ratio);
double K2 = K * K;
double a1 = 0.0625 * (1. + 3. * EI_SHAPER_VIB_TOL
+ 2. * sqrt(2. * (EI_SHAPER_VIB_TOL + 1.) * EI_SHAPER_VIB_TOL));
double a2 = 0.25 * (1. - EI_SHAPER_VIB_TOL) * K;
double a3 = (0.5 * (1. + EI_SHAPER_VIB_TOL) - 2. * a1) * K2;
double a4 = a2 * K2;
double a5 = a1 * K2 * K2;
double inv_D = 1. / (a1 + a2 + a3 + a4 + a5);
(*pulses)[0].t = -4. * half_period;
(*pulses)[1].t = -3. * half_period;
(*pulses)[2].t = -2. * half_period;
(*pulses)[3].t = -half_period;
(*pulses)[4].t = 0.;
(*pulses)[0].a = a5 * inv_D;
(*pulses)[1].a = a4 * inv_D;
(*pulses)[2].a = a3 * inv_D;
(*pulses)[3].a = a2 * inv_D;
(*pulses)[4].a = a1 * inv_D;
}
// Shift pulses around 'mid-point' t=0 so that the input shaper is an identity
// transformation for constant-speed motion (i.e. input_shaper(v * T) = v * T)
static void
shift_pulses(int n, struct shaper_pulse *pulses)
{
int i;
double ts = 0.;
for (i = 0; i < n; ++i)
ts += pulses[i].a * pulses[i].t;
for (i = 0; i < n; ++i)
pulses[i].t -= ts;
}
/****************************************************************
* Kinematics-related shaper code
****************************************************************/
#define DUMMY_T 500.0
// Optimized calc_position when only x axis is needed
static double
shaper_x_calc_position(struct stepper_kinematics *sk, struct move *m
, double move_time)
{
struct input_shaper *is = container_of(sk, struct input_shaper, sk);
if (!is->x_n)
return is->orig_sk->calc_position_cb(is->orig_sk, m, move_time);
is->m.start_pos.x = calc_position(m, 'x', move_time, is->x_pulses, is->x_n);
return is->orig_sk->calc_position_cb(is->orig_sk, &is->m, DUMMY_T);
}
// Optimized calc_position when only y axis is needed
static double
shaper_y_calc_position(struct stepper_kinematics *sk, struct move *m
, double move_time)
{
struct input_shaper *is = container_of(sk, struct input_shaper, sk);
if (!is->y_n)
return is->orig_sk->calc_position_cb(is->orig_sk, m, move_time);
is->m.start_pos.y = calc_position(m, 'y', move_time, is->y_pulses, is->y_n);
return is->orig_sk->calc_position_cb(is->orig_sk, &is->m, DUMMY_T);
}
// General calc_position for both x and y axes
static double
shaper_xy_calc_position(struct stepper_kinematics *sk, struct move *m
, double move_time)
{
struct input_shaper *is = container_of(sk, struct input_shaper, sk);
if (!is->x_n && !is->y_n)
return is->orig_sk->calc_position_cb(is->orig_sk, m, move_time);
is->m.start_pos = move_get_coord(m, move_time);
if (is->x_n)
is->m.start_pos.x = calc_position(m, 'x', move_time
, is->x_pulses, is->x_n);
if (is->y_n)
is->m.start_pos.y = calc_position(m, 'y', move_time
, is->y_pulses, is->y_n);
return is->orig_sk->calc_position_cb(is->orig_sk, &is->m, DUMMY_T);
}
static void
shaper_note_generation_time(struct input_shaper *is)
{
double pre_active = 0., post_active = 0.;
if ((is->sk.active_flags & AF_X) && is->x_n) {
pre_active = is->x_pulses[is->x_n-1].t;
post_active = -is->x_pulses[0].t;
}
if ((is->sk.active_flags & AF_Y) && is->y_n) {
pre_active = is->y_pulses[is->y_n-1].t > pre_active
? is->y_pulses[is->y_n-1].t : pre_active;
post_active = -is->y_pulses[0].t > post_active
? -is->y_pulses[0].t : post_active;
}
is->sk.gen_steps_pre_active = pre_active;
is->sk.gen_steps_post_active = post_active;
}
int __visible
input_shaper_set_sk(struct stepper_kinematics *sk
, struct stepper_kinematics *orig_sk)
{
struct input_shaper *is = container_of(sk, struct input_shaper, sk);
int af = orig_sk->active_flags & (AF_X | AF_Y);
if (af == (AF_X | AF_Y))
is->sk.calc_position_cb = shaper_xy_calc_position;
else if (af & AF_X)
is->sk.calc_position_cb = shaper_x_calc_position;
else if (af & AF_Y)
is->sk.calc_position_cb = shaper_y_calc_position;
else
return -1;
is->sk.active_flags = orig_sk->active_flags;
is->orig_sk = orig_sk;
return 0;
}
static is_init_shaper_callback init_shaper_callbacks[] = {
[INPUT_SHAPER_ZV] = &init_shaper_zv,
[INPUT_SHAPER_ZVD] = &init_shaper_zvd,
[INPUT_SHAPER_MZV] = &init_shaper_mzv,
[INPUT_SHAPER_EI] = &init_shaper_ei,
[INPUT_SHAPER_2HUMP_EI] = &init_shaper_2hump_ei,
[INPUT_SHAPER_3HUMP_EI] = &init_shaper_3hump_ei,
};
int __visible
input_shaper_set_shaper_params(struct stepper_kinematics *sk
, int shaper_type_x
, int shaper_type_y
, double shaper_freq_x
, double shaper_freq_y
, double damping_ratio_x
, double damping_ratio_y)
{
struct input_shaper *is = container_of(sk, struct input_shaper, sk);
if (shaper_type_x >= ARRAY_SIZE(init_shaper_callbacks) || shaper_type_x < 0)
return -1;
if (shaper_type_y >= ARRAY_SIZE(init_shaper_callbacks) || shaper_type_y < 0)
return -1;
int af = is->orig_sk->active_flags & (AF_X | AF_Y);
free(is->x_pulses);
if ((af & AF_X) && shaper_freq_x > 0.) {
init_shaper_callbacks[shaper_type_x](
shaper_freq_x, damping_ratio_x, &is->x_pulses, &is->x_n);
shift_pulses(is->x_n, is->x_pulses);
} else {
is->x_pulses = NULL;
is->x_n = 0;
}
free(is->y_pulses);
if ((af & AF_Y) && shaper_freq_y > 0.) {
init_shaper_callbacks[shaper_type_y](
shaper_freq_y, damping_ratio_y, &is->y_pulses, &is->y_n);
shift_pulses(is->y_n, is->y_pulses);
} else {
is->y_pulses = NULL;
is->y_n = 0;
}
shaper_note_generation_time(is);
return 0;
}
double __visible
input_shaper_get_step_generation_window(int shaper_type, double shaper_freq
, double damping_ratio)
{
if (shaper_freq <= 0.)
return 0.;
if (shaper_type >= ARRAY_SIZE(init_shaper_callbacks) || shaper_type < 0)
return 0.;
is_init_shaper_callback init_shaper_cb = init_shaper_callbacks[shaper_type];
int n;
struct shaper_pulse *pulses;
init_shaper_cb(shaper_freq, damping_ratio, &pulses, &n);
shift_pulses(n, pulses);
double window = -pulses[0].t;
if (pulses[n-1].t > window)
window = pulses[n-1].t;
free(pulses);
return window;
}
struct stepper_kinematics * __visible
input_shaper_alloc(void)
{
struct input_shaper *is = malloc(sizeof(*is));
memset(is, 0, sizeof(*is));
is->m.move_t = 2. * DUMMY_T;
return &is->sk;
}
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