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Firmware2/Marlin/planner.cpp

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/*
planner.c - buffers movement commands and manages the acceleration profile plan
Part of Grbl
Copyright (c) 2009-2011 Simen Svale Skogsrud
Grbl is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
Grbl is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with Grbl. If not, see <http://www.gnu.org/licenses/>.
*/
/* The ring buffer implementation gleaned from the wiring_serial library by David A. Mellis. */
/*
Reasoning behind the mathematics in this module (in the key of 'Mathematica'):
s == speed, a == acceleration, t == time, d == distance
Basic definitions:
Speed[s_, a_, t_] := s + (a*t)
Travel[s_, a_, t_] := Integrate[Speed[s, a, t], t]
Distance to reach a specific speed with a constant acceleration:
Solve[{Speed[s, a, t] == m, Travel[s, a, t] == d}, d, t]
d -> (m^2 - s^2)/(2 a) --> estimate_acceleration_distance()
Speed after a given distance of travel with constant acceleration:
Solve[{Speed[s, a, t] == m, Travel[s, a, t] == d}, m, t]
m -> Sqrt[2 a d + s^2]
DestinationSpeed[s_, a_, d_] := Sqrt[2 a d + s^2]
When to start braking (di) to reach a specified destionation speed (s2) after accelerating
from initial speed s1 without ever stopping at a plateau:
Solve[{DestinationSpeed[s1, a, di] == DestinationSpeed[s2, a, d - di]}, di]
di -> (2 a d - s1^2 + s2^2)/(4 a) --> intersection_distance()
IntersectionDistance[s1_, s2_, a_, d_] := (2 a d - s1^2 + s2^2)/(4 a)
*/
//#include <inttypes.h>
//#include <math.h>
//#include <stdlib.h>
#include "Marlin.h"
#include "Configuration.h"
#include "pins.h"
#include "fastio.h"
#include "planner.h"
#include "stepper.h"
#include "temperature.h"
#include "ultralcd.h"
//public variables
unsigned long minsegmenttime;
float max_feedrate[4]; // set the max speeds
float axis_steps_per_unit[4];
long max_acceleration_units_per_sq_second[4]; // Use M201 to override by software
float minimumfeedrate;
float acceleration; // Normal acceleration mm/s^2 THIS IS THE DEFAULT ACCELERATION for all moves. M204 SXXXX
float retract_acceleration; // mm/s^2 filament pull-pack and push-forward while standing still in the other axis M204 TXXXX
float max_xy_jerk; //speed than can be stopped at once, if i understand correctly.
float max_z_jerk;
float mintravelfeedrate;
unsigned long axis_steps_per_sqr_second[NUM_AXIS];
long position[4]; //rescaled from extern when axis_steps_per_unit are changed by gcode
//private variables
static block_t block_buffer[BLOCK_BUFFER_SIZE]; // A ring buffer for motion instfructions
static volatile unsigned char block_buffer_head; // Index of the next block to be pushed
static volatile unsigned char block_buffer_tail; // Index of the block to process now
// The current position of the tool in absolute steps
#define ONE_MINUTE_OF_MICROSECONDS 60000000.0
// Calculates the distance (not time) it takes to accelerate from initial_rate to target_rate using the
// given acceleration:
inline float estimate_acceleration_distance(float initial_rate, float target_rate, float acceleration) {
if (acceleration!=0) {
return((target_rate*target_rate-initial_rate*initial_rate)/
(2.0*acceleration));
}
else {
return 0.0; // acceleration was 0, set acceleration distance to 0
}
}
// This function gives you the point at which you must start braking (at the rate of -acceleration) if
// you started at speed initial_rate and accelerated until this point and want to end at the final_rate after
// a total travel of distance. This can be used to compute the intersection point between acceleration and
// deceleration in the cases where the trapezoid has no plateau (i.e. never reaches maximum speed)
inline float intersection_distance(float initial_rate, float final_rate, float acceleration, float distance) {
if (acceleration!=0) {
return((2.0*acceleration*distance-initial_rate*initial_rate+final_rate*final_rate)/
(4.0*acceleration) );
}
else {
return 0.0; // acceleration was 0, set intersection distance to 0
}
}
// Calculates trapezoid parameters so that the entry- and exit-speed is compensated by the provided factors.
void calculate_trapezoid_for_block(block_t *block, float entry_speed, float exit_speed) {
if(block->busy == true) return; // If block is busy then bail out.
float entry_factor = entry_speed / block->nominal_speed;
float exit_factor = exit_speed / block->nominal_speed;
long initial_rate = ceil(block->nominal_rate*entry_factor);
long final_rate = ceil(block->nominal_rate*exit_factor);
#ifdef ADVANCE
long initial_advance = block->advance*entry_factor*entry_factor;
long final_advance = block->advance*exit_factor*exit_factor;
#endif // ADVANCE
// Limit minimal step rate (Otherwise the timer will overflow.)
if(initial_rate <120) initial_rate=120;
if(final_rate < 120) final_rate=120;
// Calculate the acceleration steps
long acceleration = block->acceleration_st;
long accelerate_steps = estimate_acceleration_distance(initial_rate, block->nominal_rate, acceleration);
long decelerate_steps = estimate_acceleration_distance(final_rate, block->nominal_rate, acceleration);
// Calculate the size of Plateau of Nominal Rate.
long plateau_steps = block->step_event_count-accelerate_steps-decelerate_steps;
// Is the Plateau of Nominal Rate smaller than nothing? That means no cruising, and we will
// have to use intersection_distance() to calculate when to abort acceleration and start braking
// in order to reach the final_rate exactly at the end of this block.
if (plateau_steps < 0) {
accelerate_steps = intersection_distance(initial_rate, final_rate, acceleration, block->step_event_count);
plateau_steps = 0;
}
long decelerate_after = accelerate_steps+plateau_steps;
CRITICAL_SECTION_START; // Fill variables used by the stepper in a critical section
if(block->busy == false) { // Don't update variables if block is busy.
block->accelerate_until = accelerate_steps;
block->decelerate_after = decelerate_after;
block->initial_rate = initial_rate;
block->final_rate = final_rate;
#ifdef ADVANCE
block->initial_advance = initial_advance;
block->final_advance = final_advance;
#endif //ADVANCE
}
CRITICAL_SECTION_END;
}
// Calculates the maximum allowable speed at this point when you must be able to reach target_velocity using the
// acceleration within the allotted distance.
inline float max_allowable_speed(float acceleration, float target_velocity, float distance) {
return sqrt(target_velocity*target_velocity-2*acceleration*60*60*distance);
}
// "Junction jerk" in this context is the immediate change in speed at the junction of two blocks.
// This method will calculate the junction jerk as the euclidean distance between the nominal
// velocities of the respective blocks.
inline float junction_jerk(block_t *before, block_t *after) {
return sqrt(
pow((before->speed_x-after->speed_x), 2)+pow((before->speed_y-after->speed_y), 2));
}
// Return the safe speed which is max_jerk/2, e.g. the
// speed under which you cannot exceed max_jerk no matter what you do.
float safe_speed(block_t *block) {
float safe_speed;
safe_speed = max_xy_jerk/2;
if(abs(block->speed_z) > max_z_jerk/2)
safe_speed = max_z_jerk/2;
if (safe_speed > block->nominal_speed)
safe_speed = block->nominal_speed;
return safe_speed;
}
// The kernel called by planner_recalculate() when scanning the plan from last to first entry.
void planner_reverse_pass_kernel(block_t *previous, block_t *current, block_t *next) {
if(!current) {
return;
}
float entry_speed = current->nominal_speed;
float exit_factor;
float exit_speed;
if (next) {
exit_speed = next->entry_speed;
}
else {
exit_speed = safe_speed(current);
}
// Calculate the entry_factor for the current block.
if (previous) {
// Reduce speed so that junction_jerk is within the maximum allowed
float jerk = junction_jerk(previous, current);
if((previous->steps_x == 0) && (previous->steps_y == 0)) {
entry_speed = safe_speed(current);
}
else if (jerk > max_xy_jerk) {
entry_speed = (max_xy_jerk/jerk) * entry_speed;
}
if(abs(previous->speed_z - current->speed_z) > max_z_jerk) {
entry_speed = (max_z_jerk/abs(previous->speed_z - current->speed_z)) * entry_speed;
}
// If the required deceleration across the block is too rapid, reduce the entry_factor accordingly.
if (entry_speed > exit_speed) {
float max_entry_speed = max_allowable_speed(-current->acceleration,exit_speed, current->millimeters);
if (max_entry_speed < entry_speed) {
entry_speed = max_entry_speed;
}
}
}
else {
entry_speed = safe_speed(current);
}
// Store result
current->entry_speed = entry_speed;
}
// planner_recalculate() needs to go over the current plan twice. Once in reverse and once forward. This
// implements the reverse pass.
void planner_reverse_pass() {
char block_index = block_buffer_head;
if(((block_buffer_head-block_buffer_tail + BLOCK_BUFFER_SIZE) & (BLOCK_BUFFER_SIZE - 1)) > 3) {
block_index = (block_buffer_head - 3) & (BLOCK_BUFFER_SIZE - 1);
block_t *block[5] = {
NULL, NULL, NULL, NULL, NULL };
while(block_index != block_buffer_tail) {
block_index = (block_index-1) & (BLOCK_BUFFER_SIZE -1);
block[2]= block[1];
block[1]= block[0];
block[0] = &block_buffer[block_index];
planner_reverse_pass_kernel(block[0], block[1], block[2]);
}
planner_reverse_pass_kernel(NULL, block[0], block[1]);
}
}
// The kernel called by planner_recalculate() when scanning the plan from first to last entry.
void planner_forward_pass_kernel(block_t *previous, block_t *current, block_t *next) {
if(!current) {
return;
}
if(previous) {
// If the previous block is an acceleration block, but it is not long enough to
// complete the full speed change within the block, we need to adjust out entry
// speed accordingly. Remember current->entry_factor equals the exit factor of
// the previous block.
if(previous->entry_speed < current->entry_speed) {
float max_entry_speed = max_allowable_speed(-previous->acceleration, previous->entry_speed, previous->millimeters);
if (max_entry_speed < current->entry_speed) {
current->entry_speed = max_entry_speed;
}
}
}
}
// planner_recalculate() needs to go over the current plan twice. Once in reverse and once forward. This
// implements the forward pass.
void planner_forward_pass() {
char block_index = block_buffer_tail;
block_t *block[3] = {
NULL, NULL, NULL };
while(block_index != block_buffer_head) {
block[0] = block[1];
block[1] = block[2];
block[2] = &block_buffer[block_index];
planner_forward_pass_kernel(block[0],block[1],block[2]);
block_index = (block_index+1) & (BLOCK_BUFFER_SIZE - 1);
}
planner_forward_pass_kernel(block[1], block[2], NULL);
}
// Recalculates the trapezoid speed profiles for all blocks in the plan according to the
// entry_factor for each junction. Must be called by planner_recalculate() after
// updating the blocks.
void planner_recalculate_trapezoids() {
char block_index = block_buffer_tail;
block_t *current;
block_t *next = NULL;
while(block_index != block_buffer_head) {
current = next;
next = &block_buffer[block_index];
if (current) {
calculate_trapezoid_for_block(current, current->entry_speed, next->entry_speed);
}
block_index = (block_index+1) & (BLOCK_BUFFER_SIZE - 1);
}
calculate_trapezoid_for_block(next, next->entry_speed, safe_speed(next));
}
// Recalculates the motion plan according to the following algorithm:
//
// 1. Go over every block in reverse order and calculate a junction speed reduction (i.e. block_t.entry_factor)
// so that:
// a. The junction jerk is within the set limit
// b. No speed reduction within one block requires faster deceleration than the one, true constant
// acceleration.
// 2. Go over every block in chronological order and dial down junction speed reduction values if
// a. The speed increase within one block would require faster accelleration than the one, true
// constant acceleration.
//
// When these stages are complete all blocks have an entry_factor that will allow all speed changes to
// be performed using only the one, true constant acceleration, and where no junction jerk is jerkier than
// the set limit. Finally it will:
//
// 3. Recalculate trapezoids for all blocks.
void planner_recalculate() {
planner_reverse_pass();
planner_forward_pass();
planner_recalculate_trapezoids();
}
void plan_init() {
block_buffer_head = 0;
block_buffer_tail = 0;
memset(position, 0, sizeof(position)); // clear position
}
void plan_discard_current_block() {
if (block_buffer_head != block_buffer_tail) {
block_buffer_tail = (block_buffer_tail + 1) & (BLOCK_BUFFER_SIZE - 1);
}
}
block_t *plan_get_current_block() {
if (block_buffer_head == block_buffer_tail) {
return(NULL);
}
block_t *block = &block_buffer[block_buffer_tail];
block->busy = true;
return(block);
}
void check_axes_activity() {
unsigned char x_active = 0;
unsigned char y_active = 0;
unsigned char z_active = 0;
unsigned char e_active = 0;
block_t *block;
if(block_buffer_tail != block_buffer_head) {
char block_index = block_buffer_tail;
while(block_index != block_buffer_head) {
block = &block_buffer[block_index];
if(block->steps_x != 0) x_active++;
if(block->steps_y != 0) y_active++;
if(block->steps_z != 0) z_active++;
if(block->steps_e != 0) e_active++;
block_index = (block_index+1) & (BLOCK_BUFFER_SIZE - 1);
}
}
if((DISABLE_X) && (x_active == 0)) disable_x();
if((DISABLE_Y) && (y_active == 0)) disable_y();
if((DISABLE_Z) && (z_active == 0)) disable_z();
if((DISABLE_E) && (e_active == 0)) disable_e();
}
// Add a new linear movement to the buffer. steps_x, _y and _z is the absolute position in
// mm. Microseconds specify how many microseconds the move should take to perform. To aid acceleration
// calculation the caller must also provide the physical length of the line in millimeters.
void plan_buffer_line(const float &x, const float &y, const float &z, const float &e, float feed_rate)
{
// Calculate the buffer head after we push this byte
int next_buffer_head = (block_buffer_head + 1) & (BLOCK_BUFFER_SIZE - 1);
// If the buffer is full: good! That means we are well ahead of the robot.
// Rest here until there is room in the buffer.
while(block_buffer_tail == next_buffer_head) {
manage_heater();
manage_inactivity(1);
LCD_STATUS;
}
// The target position of the tool in absolute steps
// Calculate target position in absolute steps
//this should be done after the wait, because otherwise a M92 code within the gcode disrupts this calculation somehow
long target[4];
target[X_AXIS] = lround(x*axis_steps_per_unit[X_AXIS]);
target[Y_AXIS] = lround(y*axis_steps_per_unit[Y_AXIS]);
target[Z_AXIS] = lround(z*axis_steps_per_unit[Z_AXIS]);
target[E_AXIS] = lround(e*axis_steps_per_unit[E_AXIS]);
// Prepare to set up new block
block_t *block = &block_buffer[block_buffer_head];
// Mark block as not busy (Not executed by the stepper interrupt)
block->busy = false;
// Number of steps for each axis
block->steps_x = labs(target[X_AXIS]-position[X_AXIS]);
block->steps_y = labs(target[Y_AXIS]-position[Y_AXIS]);
block->steps_z = labs(target[Z_AXIS]-position[Z_AXIS]);
block->steps_e = labs(target[E_AXIS]-position[E_AXIS]);
block->step_event_count = max(block->steps_x, max(block->steps_y, max(block->steps_z, block->steps_e)));
// Bail if this is a zero-length block
if (block->step_event_count <=dropsegments) {
return;
};
//enable active axes
if(block->steps_x != 0) enable_x();
if(block->steps_y != 0) enable_y();
if(block->steps_z != 0) enable_z();
if(block->steps_e != 0) enable_e();
float delta_x_mm = (target[X_AXIS]-position[X_AXIS])/axis_steps_per_unit[X_AXIS];
float delta_y_mm = (target[Y_AXIS]-position[Y_AXIS])/axis_steps_per_unit[Y_AXIS];
float delta_z_mm = (target[Z_AXIS]-position[Z_AXIS])/axis_steps_per_unit[Z_AXIS];
float delta_e_mm = (target[E_AXIS]-position[E_AXIS])/axis_steps_per_unit[E_AXIS];
block->millimeters = sqrt(square(delta_x_mm) + square(delta_y_mm) + square(delta_z_mm) + square(delta_e_mm));
unsigned long microseconds;
if (block->steps_e == 0) {
if(feed_rate<mintravelfeedrate) feed_rate=mintravelfeedrate;
}
else {
if(feed_rate<minimumfeedrate) feed_rate=minimumfeedrate;
}
microseconds = lround((block->millimeters/feed_rate)*1000000);
// slow down when de buffer starts to empty, rather than wait at the corner for a buffer refill
// reduces/removes corner blobs as the machine won't come to a full stop.
int blockcount=(block_buffer_head-block_buffer_tail + BLOCK_BUFFER_SIZE) & (BLOCK_BUFFER_SIZE - 1);
if ((blockcount>0) && (blockcount < (BLOCK_BUFFER_SIZE - 4))) {
if (microseconds<minsegmenttime) { // buffer is draining, add extra time. The amount of time added increases if the buffer is still emptied more.
microseconds=microseconds+lround(2*(minsegmenttime-microseconds)/blockcount);
}
}
else {
if (microseconds<minsegmenttime) microseconds=minsegmenttime;
}
// END OF SLOW DOWN SECTION
// Calculate speed in mm/minute for each axis
float multiplier = 60.0*1000000.0/microseconds;
block->speed_z = delta_z_mm * multiplier;
block->speed_x = delta_x_mm * multiplier;
block->speed_y = delta_y_mm * multiplier;
block->speed_e = delta_e_mm * multiplier;
// Limit speed per axis
float speed_factor = 1; //factor <=1 do decrease speed
if(abs(block->speed_x) > max_feedrate[X_AXIS]) {
speed_factor = max_feedrate[X_AXIS] / abs(block->speed_x);
//if(speed_factor > tmp_speed_factor) speed_factor = tmp_speed_factor; /is not need here because auf the init above
}
if(abs(block->speed_y) > max_feedrate[Y_AXIS]){
float tmp_speed_factor = max_feedrate[Y_AXIS] / abs(block->speed_y);
if(speed_factor > tmp_speed_factor) speed_factor = tmp_speed_factor;
}
if(abs(block->speed_z) > max_feedrate[Z_AXIS]){
float tmp_speed_factor = max_feedrate[Z_AXIS] / abs(block->speed_z);
if(speed_factor > tmp_speed_factor) speed_factor = tmp_speed_factor;
}
if(abs(block->speed_e) > max_feedrate[E_AXIS]){
float tmp_speed_factor = max_feedrate[E_AXIS] / abs(block->speed_e);
if(speed_factor > tmp_speed_factor) speed_factor = tmp_speed_factor;
}
multiplier = multiplier * speed_factor;
block->speed_z = delta_z_mm * multiplier;
block->speed_x = delta_x_mm * multiplier;
block->speed_y = delta_y_mm * multiplier;
block->speed_e = delta_e_mm * multiplier;
block->nominal_speed = block->millimeters * multiplier;
block->nominal_rate = ceil(block->step_event_count * multiplier / 60);
if(block->nominal_rate < 120)
block->nominal_rate = 120;
block->entry_speed = safe_speed(block);
// Compute the acceleration rate for the trapezoid generator.
float travel_per_step = block->millimeters/block->step_event_count;
if(block->steps_x == 0 && block->steps_y == 0 && block->steps_z == 0) {
block->acceleration_st = ceil( (retract_acceleration)/travel_per_step); // convert to: acceleration steps/sec^2
}
else {
block->acceleration_st = ceil( (acceleration)/travel_per_step); // convert to: acceleration steps/sec^2
float tmp_acceleration = (float)block->acceleration_st / (float)block->step_event_count;
// Limit acceleration per axis
if((tmp_acceleration * block->steps_x) > axis_steps_per_sqr_second[X_AXIS]) {
block->acceleration_st = axis_steps_per_sqr_second[X_AXIS];
tmp_acceleration = (float)block->acceleration_st / (float)block->step_event_count;
}
if((tmp_acceleration * block->steps_y) > axis_steps_per_sqr_second[Y_AXIS]) {
block->acceleration_st = axis_steps_per_sqr_second[Y_AXIS];
tmp_acceleration = (float)block->acceleration_st / (float)block->step_event_count;
}
if((tmp_acceleration * block->steps_e) > axis_steps_per_sqr_second[E_AXIS]) {
block->acceleration_st = axis_steps_per_sqr_second[E_AXIS];
tmp_acceleration = (float)block->acceleration_st / (float)block->step_event_count;
}
if((tmp_acceleration * block->steps_z) > axis_steps_per_sqr_second[Z_AXIS]) {
block->acceleration_st = axis_steps_per_sqr_second[Z_AXIS];
tmp_acceleration = (float)block->acceleration_st / (float)block->step_event_count;
}
}
block->acceleration = block->acceleration_st * travel_per_step;
block->acceleration_rate = (long)((float)block->acceleration_st * 8.388608);
#ifdef ADVANCE
// Calculate advance rate
if((block->steps_e == 0) || (block->steps_x == 0 && block->steps_y == 0 && block->steps_z == 0)) {
block->advance_rate = 0;
block->advance = 0;
}
else {
long acc_dist = estimate_acceleration_distance(0, block->nominal_rate, block->acceleration_st);
float advance = (STEPS_PER_CUBIC_MM_E * EXTRUDER_ADVANCE_K) *
(block->speed_e * block->speed_e * EXTRUTION_AREA * EXTRUTION_AREA / 3600.0)*65536;
block->advance = advance;
if(acc_dist == 0) {
block->advance_rate = 0;
}
else {
block->advance_rate = advance / (float)acc_dist;
}
}
#endif // ADVANCE
// compute a preliminary conservative acceleration trapezoid
float safespeed = safe_speed(block);
calculate_trapezoid_for_block(block, safespeed, safespeed);
// Compute direction bits for this block
block->direction_bits = 0;
if (target[X_AXIS] < position[X_AXIS]) {
block->direction_bits |= (1<<X_AXIS);
}
if (target[Y_AXIS] < position[Y_AXIS]) {
block->direction_bits |= (1<<Y_AXIS);
}
if (target[Z_AXIS] < position[Z_AXIS]) {
block->direction_bits |= (1<<Z_AXIS);
}
if (target[E_AXIS] < position[E_AXIS]) {
block->direction_bits |= (1<<E_AXIS);
}
// Move buffer head
block_buffer_head = next_buffer_head;
// Update position
memcpy(position, target, sizeof(target)); // position[] = target[]
planner_recalculate();
st_wake_up();
}
void plan_set_position(const float &x, const float &y, const float &z, const float &e)
{
position[X_AXIS] = lround(x*axis_steps_per_unit[X_AXIS]);
position[Y_AXIS] = lround(y*axis_steps_per_unit[Y_AXIS]);
position[Z_AXIS] = lround(z*axis_steps_per_unit[Z_AXIS]);
position[E_AXIS] = lround(e*axis_steps_per_unit[E_AXIS]);
}
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