147 lines
6.6 KiB
C
147 lines
6.6 KiB
C
/*
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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 <stdlib.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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#include "config.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; // Index of the next block to be pushed
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volatile int block_buffer_tail; // Index of the block to process now
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uint8_t acceleration_management; // Acceleration management active?
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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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void mp_enable_acceleration_management() {
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if (!acceleration_management) {
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st_synchronize();
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acceleration_management = TRUE;
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}
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}
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void mp_disable_acceleration_management() {
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if(acceleration_management) {
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st_synchronize();
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acceleration_management = FALSE;
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}
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}
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void mp_init() {
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block_buffer_head = 0;
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block_buffer_tail = 0;
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mp_enable_acceleration_management();
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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 = round(block->nominal_rate*entry_factor);
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int32_t final_rate = round(block->nominal_rate*entry_factor);
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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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// Add a new linear movement to the buffer. steps_x, _y and _z is the signed, relative motion in
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// steps. Microseconds specify how many microseconds the move should take to perform. To aid acceleration
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// calculation the caller must also provide the physical length of the line in millimeters.
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void mp_buffer_line(int32_t steps_x, int32_t steps_y, int32_t steps_z, uint32_t microseconds, double millimeters) {
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// Calculate the buffer head after we push this byte
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int next_buffer_head = (block_buffer_head + 1) % BLOCK_BUFFER_SIZE;
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// If the buffer is full: good! That means we are well ahead of the robot.
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// Rest here until there is room in the buffer.
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while(block_buffer_tail == next_buffer_head) { sleep_mode(); }
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// Prepare to set up new block
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struct Block *block = &block_buffer[block_buffer_head];
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// Number of steps for each axis
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block->steps_x = labs(steps_x);
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block->steps_y = labs(steps_y);
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block->steps_z = labs(steps_z);
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block->step_event_count = max(block->steps_x, max(block->steps_y, block->steps_z));
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// Bail if this is a zero-length block
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if (block->step_event_count == 0) { return; };
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// Calculate speed in mm/minute for each axis
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double multiplier = 60.0*1000000.0/microseconds;
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block->speed_x = block->steps_x*multiplier/settings.steps_per_mm[0];
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block->speed_y = block->steps_y*multiplier/settings.steps_per_mm[1];
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block->speed_z = block->steps_z*multiplier/settings.steps_per_mm[2];
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block->nominal_rate = round(block->step_event_count*multiplier);
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// Compute the acceleration rate for the trapezoid generator. Depending on the slope of the line
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// average travel per step event changes. For a line along one axis the travel per step event
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// is equal to the travel/step in the particular axis. For a 45 degree line the steppers of both
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// axes might step for every step event. Travel per step event is then sqrt(travel_x^2+travel_y^2).
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// To generate trapezoids with contant acceleration between blocks the rate_delta must be computed
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// specifically for each line to compensate for this phenomenon:
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double travel_per_step = (1.0*millimeters)/block->step_event_count;
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block->rate_delta = round(
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(settings.acceleration/(60.0*ACCELERATION_TICKS_PER_SECOND))/ // acceleration mm/min per acceleration_tick
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travel_per_step); // convert to: acceleration steps/min/acceleration_tick
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if (acceleration_management) {
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calculate_trapezoid_for_block(block,0,0); // compute a conservative acceleration trapezoid for now
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} else {
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block->accelerate_ticks = 0;
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block->plateau_ticks = 0;
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block->rate_delta = 0;
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}
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// Compute direction bits for this block
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block->direction_bits = 0;
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if (steps_x < 0) { block->direction_bits |= (1<<X_DIRECTION_BIT); }
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if (steps_y < 0) { block->direction_bits |= (1<<Y_DIRECTION_BIT); }
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if (steps_z < 0) { block->direction_bits |= (1<<Z_DIRECTION_BIT); }
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// Move buffer head
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block_buffer_head = next_buffer_head;
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}
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