70 lines
3.2 KiB
C
70 lines
3.2 KiB
C
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/*
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motion_plan.c - buffers movement commands and manages the acceleration profile plan
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Part of Grbl
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Copyright (c) 2009-2011 Simen Svale Skogsrud
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Grbl 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 3 of the License, or
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(at your option) any later version.
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Grbl 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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You should have received a copy of the GNU General Public License
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along with Grbl. If not, see <http://www.gnu.org/licenses/>.
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*/
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#include <inttypes.h>
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#include <math.h>
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#include "motion_plan.h"
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#include "nuts_bolts.h"
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#include "stepper.h"
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struct Block block_buffer[BLOCK_BUFFER_SIZE]; // A ring buffer for motion instructions
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volatile int block_buffer_head = 0; // Index of the next block to be pushed
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volatile int block_buffer_tail = 0; // Index of the block to process now
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inline uint32_t estimate_acceleration_distance(int32_t current_rate, int32_t target_rate, int32_t acceleration) {
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return((target_rate*target_rate-current_rate*current_rate)/(2*acceleration));
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}
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inline uint32_t estimate_acceleration_ticks(int32_t start_rate, int32_t acceleration_per_tick, int32_t step_events) {
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return(
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round(
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(sqrt(2*acceleration_per_tick*step_events+(start_rate*start_rate))-start_rate)/
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acceleration_per_tick));
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}
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// Calculates trapezoid parameters so that the entry- and exit-speed is compensated by the provided factors.
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// In practice both factors must be in the range 0 ... 1.0
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void calculate_trapezoid_for_block(struct Block *block, double entry_factor, double exit_factor) {
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block->initial_rate = max(round(block->nominal_rate*entry_factor),MINIMAL_STEP_RATE);
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int32_t final_rate = max(round(block->nominal_rate*entry_factor),MINIMAL_STEP_RATE);
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int32_t acceleration_per_second = block->rate_delta*ACCELERATION_TICKS_PER_SECOND;
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int32_t acceleration_steps =
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estimate_acceleration_distance(block->initial_rate, block->nominal_rate, acceleration_per_second);
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int32_t decelleration_steps =
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estimate_acceleration_distance(block->nominal_rate, final_rate, -acceleration_per_second);
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// Check if the acceleration and decelleration periods overlap. In that case nominal_speed will
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// never be reached but that's okay. Just truncate both periods proportionally so that they
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// fit within the allotted step events.
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int32_t plateau_steps = block->step_event_count-acceleration_steps-decelleration_steps;
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if (plateau_steps < 0) {
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int32_t half_overlap_region = fabs(plateau_steps)/2;
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plateau_steps = 0;
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acceleration_steps = max(acceleration_steps-half_overlap_region,0);
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decelleration_steps = max(decelleration_steps-half_overlap_region,0);
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}
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block->accelerate_ticks = estimate_acceleration_ticks(block->initial_rate, block->rate_delta, acceleration_steps);
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if (plateau_steps) {
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block->plateau_ticks = round(1.0*plateau_steps/(block->nominal_rate*ACCELERATION_TICKS_PER_SECOND));
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} else {
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block->plateau_ticks = 0;
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}
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}
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