281 lines
10 KiB
C
281 lines
10 KiB
C
// Iterative solver for kinematic moves
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//
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// Copyright (C) 2018-2020 Kevin O'Connor <kevin@koconnor.net>
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//
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// This file may be distributed under the terms of the GNU GPLv3 license.
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#include <math.h> // fabs
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#include <stddef.h> // offsetof
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#include <string.h> // memset
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#include "compiler.h" // __visible
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#include "itersolve.h" // itersolve_generate_steps
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#include "pyhelper.h" // errorf
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#include "stepcompress.h" // queue_append_start
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#include "trapq.h" // struct move
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/****************************************************************
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* Main iterative solver
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****************************************************************/
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struct timepos {
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double time, position;
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};
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#define SEEK_TIME_RESET 0.000100
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// Generate step times for a portion of a move
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static int32_t
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itersolve_gen_steps_range(struct stepper_kinematics *sk, struct move *m
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, double abs_start, double abs_end)
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{
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sk_calc_callback calc_position_cb = sk->calc_position_cb;
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double half_step = .5 * sk->step_dist;
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double start = abs_start - m->print_time, end = abs_end - m->print_time;
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if (start < 0.)
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start = 0.;
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if (end > m->move_t)
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end = m->move_t;
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struct timepos old_guess = {start, sk->commanded_pos}, guess = old_guess;
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int sdir = stepcompress_get_step_dir(sk->sc);
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int is_dir_change = 0, have_bracket = 0, check_oscillate = 0;
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double target = sk->commanded_pos + (sdir ? half_step : -half_step);
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double last_time=start, low_time=start, high_time=start + SEEK_TIME_RESET;
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if (high_time > end)
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high_time = end;
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for (;;) {
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// Use the "secant method" to guess a new time from previous guesses
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double guess_dist = guess.position - target;
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double og_dist = old_guess.position - target;
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double next_time = ((old_guess.time*guess_dist - guess.time*og_dist)
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/ (guess_dist - og_dist));
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if (!(next_time > low_time && next_time < high_time)) { // or NaN
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// Next guess is outside bounds checks - validate it
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if (have_bracket) {
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// A poor guess - fall back to bisection
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next_time = (low_time + high_time) * .5;
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check_oscillate = 0;
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} else if (guess.time >= end) {
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// No more steps present in requested time range
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break;
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} else {
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// Might be a poor guess - limit to exponential search
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next_time = high_time;
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high_time = 2. * high_time - last_time;
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if (high_time > end)
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high_time = end;
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}
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}
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// Calculate position at next_time guess
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old_guess = guess;
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guess.time = next_time;
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guess.position = calc_position_cb(sk, m, next_time);
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guess_dist = guess.position - target;
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if (fabs(guess_dist) > .000000001) {
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// Guess does not look close enough - update bounds
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double rel_dist = sdir ? guess_dist : -guess_dist;
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if (rel_dist > 0.) {
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// Found position past target, so step is definitely present
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if (have_bracket && old_guess.time <= low_time) {
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if (check_oscillate)
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// Force bisect next to avoid persistent oscillations
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old_guess = guess;
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check_oscillate = 1;
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}
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high_time = guess.time;
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have_bracket = 1;
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} else if (rel_dist < -(half_step + half_step + .000000010)) {
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// Found direction change
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sdir = !sdir;
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target = (sdir ? target + half_step + half_step
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: target - half_step - half_step);
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low_time = last_time;
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high_time = guess.time;
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is_dir_change = have_bracket = 1;
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check_oscillate = 0;
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} else {
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low_time = guess.time;
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}
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if (!have_bracket || high_time - low_time > .000000001) {
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if (!is_dir_change && rel_dist >= -half_step)
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// Avoid rollback if stepper fully reaches step position
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stepcompress_commit(sk->sc);
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// Guess is not close enough - guess again with new time
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continue;
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}
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}
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// Found next step - submit it
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int ret = stepcompress_append(sk->sc, sdir, m->print_time, guess.time);
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if (ret)
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return ret;
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target = sdir ? target+half_step+half_step : target-half_step-half_step;
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// Reset bounds checking
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double seek_time_delta = 1.5 * (guess.time - last_time);
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if (seek_time_delta < .000000001)
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seek_time_delta = .000000001;
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if (is_dir_change && seek_time_delta > SEEK_TIME_RESET)
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seek_time_delta = SEEK_TIME_RESET;
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last_time = low_time = guess.time;
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high_time = guess.time + seek_time_delta;
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if (high_time > end)
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high_time = end;
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is_dir_change = have_bracket = check_oscillate = 0;
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}
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sk->commanded_pos = target - (sdir ? half_step : -half_step);
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if (sk->post_cb)
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sk->post_cb(sk);
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return 0;
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}
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/****************************************************************
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* Interface functions
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****************************************************************/
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// Check if a move is likely to cause movement on a stepper
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static inline int
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check_active(struct stepper_kinematics *sk, struct move *m)
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{
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int af = sk->active_flags;
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return ((af & AF_X && m->axes_r.x != 0.)
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|| (af & AF_Y && m->axes_r.y != 0.)
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|| (af & AF_Z && m->axes_r.z != 0.));
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}
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// Generate step times for a range of moves on the trapq
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int32_t __visible
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itersolve_generate_steps(struct stepper_kinematics *sk, double flush_time)
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{
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double last_flush_time = sk->last_flush_time;
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sk->last_flush_time = flush_time;
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if (!sk->tq)
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return 0;
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trapq_check_sentinels(sk->tq);
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struct move *m = list_first_entry(&sk->tq->moves, struct move, node);
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while (last_flush_time >= m->print_time + m->move_t)
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m = list_next_entry(m, node);
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double force_steps_time = sk->last_move_time + sk->gen_steps_post_active;
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int skip_count = 0;
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for (;;) {
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double move_start = m->print_time, move_end = move_start + m->move_t;
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if (check_active(sk, m)) {
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if (skip_count && sk->gen_steps_pre_active) {
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// Must generate steps leading up to stepper activity
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double abs_start = move_start - sk->gen_steps_pre_active;
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if (abs_start < last_flush_time)
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abs_start = last_flush_time;
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if (abs_start < force_steps_time)
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abs_start = force_steps_time;
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struct move *pm = list_prev_entry(m, node);
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while (--skip_count && pm->print_time > abs_start)
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pm = list_prev_entry(pm, node);
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do {
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int32_t ret = itersolve_gen_steps_range(sk, pm, abs_start
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, flush_time);
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if (ret)
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return ret;
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pm = list_next_entry(pm, node);
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} while (pm != m);
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}
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// Generate steps for this move
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int32_t ret = itersolve_gen_steps_range(sk, m, last_flush_time
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, flush_time);
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if (ret)
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return ret;
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if (move_end >= flush_time) {
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sk->last_move_time = flush_time;
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return 0;
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}
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skip_count = 0;
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sk->last_move_time = move_end;
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force_steps_time = sk->last_move_time + sk->gen_steps_post_active;
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} else {
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if (move_start < force_steps_time) {
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// Must generates steps just past stepper activity
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double abs_end = force_steps_time;
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if (abs_end > flush_time)
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abs_end = flush_time;
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int32_t ret = itersolve_gen_steps_range(sk, m, last_flush_time
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, abs_end);
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if (ret)
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return ret;
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skip_count = 1;
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} else {
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// This move doesn't impact this stepper - skip it
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skip_count++;
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}
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if (flush_time + sk->gen_steps_pre_active <= move_end)
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return 0;
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}
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m = list_next_entry(m, node);
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}
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}
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// Check if the given stepper is likely to be active in the given time range
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double __visible
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itersolve_check_active(struct stepper_kinematics *sk, double flush_time)
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{
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if (!sk->tq)
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return 0.;
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trapq_check_sentinels(sk->tq);
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struct move *m = list_first_entry(&sk->tq->moves, struct move, node);
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while (sk->last_flush_time >= m->print_time + m->move_t)
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m = list_next_entry(m, node);
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for (;;) {
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if (check_active(sk, m))
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return m->print_time;
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if (flush_time <= m->print_time + m->move_t)
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return 0.;
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m = list_next_entry(m, node);
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}
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}
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// Report if the given stepper is registered for the given axis
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int32_t __visible
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itersolve_is_active_axis(struct stepper_kinematics *sk, char axis)
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{
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if (axis < 'x' || axis > 'z')
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return 0;
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return (sk->active_flags & (AF_X << (axis - 'x'))) != 0;
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}
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void __visible
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itersolve_set_trapq(struct stepper_kinematics *sk, struct trapq *tq)
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{
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sk->tq = tq;
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}
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void __visible
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itersolve_set_stepcompress(struct stepper_kinematics *sk
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, struct stepcompress *sc, double step_dist)
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{
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sk->sc = sc;
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sk->step_dist = step_dist;
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}
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double __visible
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itersolve_calc_position_from_coord(struct stepper_kinematics *sk
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, double x, double y, double z)
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{
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struct move m;
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memset(&m, 0, sizeof(m));
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m.start_pos.x = x;
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m.start_pos.y = y;
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m.start_pos.z = z;
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m.move_t = 1000.;
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return sk->calc_position_cb(sk, &m, 500.);
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}
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void __visible
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itersolve_set_position(struct stepper_kinematics *sk
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, double x, double y, double z)
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{
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sk->commanded_pos = itersolve_calc_position_from_coord(sk, x, y, z);
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}
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double __visible
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itersolve_get_commanded_pos(struct stepper_kinematics *sk)
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{
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return sk->commanded_pos;
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}
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