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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];
// The current position of the tool in absolute steps
long position[4]; //rescaled from extern when axis_steps_per_unit are changed by gcode
static float previous_speed[4]; // Speed of previous path line segment
static float previous_nominal_speed; // Nominal speed of previous path line segment
#ifdef AUTOTEMP
float high_e_speed=0;
#endif
//===========================================================================
//=============================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
// Used for the frequency limit
static unsigned char old_direction_bits = 0; // Old direction bits. Used for speed calculations
static long x_segment_time[3]={0,0,0}; // Segment times (in us). Used for speed calculations
static long y_segment_time[3]={0,0,0};
// Returns the index of the next block in the ring buffer
// NOTE: Removed modulo (%) operator, which uses an expensive divide and multiplication.
static int8_t next_block_index(int8_t block_index) {
block_index++;
if (block_index == BLOCK_BUFFER_SIZE) { block_index = 0; }
return(block_index);
}
// Returns the index of the previous block in the ring buffer
static int8_t prev_block_index(int8_t block_index) {
if (block_index == 0) { block_index = BLOCK_BUFFER_SIZE; }
block_index--;
return(block_index);
}
//===========================================================================
//=============================functions ============================
//===========================================================================
// 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_factor, float exit_factor) {
long initial_rate = ceil(block->nominal_rate*entry_factor); // (step/min)
long final_rate = ceil(block->nominal_rate*exit_factor); // (step/min)
// Limit minimal step rate (Otherwise the timer will overflow.)
if(initial_rate <120) {initial_rate=120; }
if(final_rate < 120) {final_rate=120; }
long acceleration = block->acceleration_st;
int32_t accelerate_steps =
ceil(estimate_acceleration_distance(block->initial_rate, block->nominal_rate, acceleration));
int32_t decelerate_steps =
floor(estimate_acceleration_distance(block->nominal_rate, block->final_rate, -acceleration));
// Calculate the size of Plateau of Nominal Rate.
int32_t 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 = ceil(
intersection_distance(block->initial_rate, block->final_rate, acceleration, block->step_event_count));
accelerate_steps = max(accelerate_steps,0); // Check limits due to numerical round-off
accelerate_steps = min(accelerate_steps,block->step_event_count);
plateau_steps = 0;
}
#ifdef ADVANCE
long initial_advance = block->advance*entry_factor*entry_factor;
long final_advance = block->advance*exit_factor*exit_factor;
#endif // ADVANCE
// block->accelerate_until = accelerate_steps;
// block->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 = accelerate_steps+plateau_steps;
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*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));
//}
// 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; }
if (next) {
// If entry speed is already at the maximum entry speed, no need to recheck. Block is cruising.
// If not, block in state of acceleration or deceleration. Reset entry speed to maximum and
// check for maximum allowable speed reductions to ensure maximum possible planned speed.
if (current->entry_speed != current->max_entry_speed) {
// If nominal length true, max junction speed is guaranteed to be reached. Only compute
// for max allowable speed if block is decelerating and nominal length is false.
if ((!current->nominal_length_flag) && (current->max_entry_speed > next->entry_speed)) {
current->entry_speed = min( current->max_entry_speed,
max_allowable_speed(-current->acceleration,next->entry_speed,current->millimeters));
} else {
current->entry_speed = current->max_entry_speed;
}
current->recalculate_flag = true;
}
} // Skip last block. Already initialized and set for recalculation.
}
// 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[3] = { NULL, NULL, NULL };
while(block_index != block_buffer_tail) {
block_index = prev_block_index(block_index);
block[2]= block[1];
block[1]= block[0];
block[0] = &block_buffer[block_index];
planner_reverse_pass_kernel(block[0], block[1], block[2]);
}
}
}
// 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(!previous) { return; }
// 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 the entry speed accordingly. Entry
// speeds have already been reset, maximized, and reverse planned by reverse planner.
// If nominal length is true, max junction speed is guaranteed to be reached. No need to recheck.
if (!previous->nominal_length_flag) {
if (previous->entry_speed < current->entry_speed) {
double entry_speed = min( current->entry_speed,
max_allowable_speed(-previous->acceleration,previous->entry_speed,previous->millimeters) );
// Check for junction speed change
if (current->entry_speed != entry_speed) {
current->entry_speed = entry_speed;
current->recalculate_flag = true;
}
}
}
}
// 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 = next_block_index(block_index);
}
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() {
int8_t 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) {
// Recalculate if current block entry or exit junction speed has changed.
if (current->recalculate_flag || next->recalculate_flag) {
// NOTE: Entry and exit factors always > 0 by all previous logic operations.
calculate_trapezoid_for_block(current, current->entry_speed/current->nominal_speed,
next->entry_speed/current->nominal_speed);
current->recalculate_flag = false; // Reset current only to ensure next trapezoid is computed
}
}
block_index = next_block_index( block_index );
}
// Last/newest block in buffer. Exit speed is set with MINIMUM_PLANNER_SPEED. Always recalculated.
if(next != NULL) {
calculate_trapezoid_for_block(next, next->entry_speed/next->nominal_speed,
MINIMUM_PLANNER_SPEED/next->nominal_speed);
next->recalculate_flag = false;
}
}
// 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
previous_speed[0] = 0.0;
previous_speed[1] = 0.0;
previous_speed[2] = 0.0;
previous_speed[3] = 0.0;
previous_nominal_speed = 0.0;
}
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);
}
#ifdef AUTOTEMP
void getHighESpeed()
{
if(degTargetHotend0()+2<AUTOTEMP_MIN) //probably temperature set to zero.
return; //do nothing
float high=0;
char block_index = block_buffer_tail;
while(block_index != block_buffer_head) {
float se=block_buffer[block_index].speed_e;
if(se>high)
{
high=se;
}
block_index = (block_index+1) & (BLOCK_BUFFER_SIZE - 1);
}
high_e_speed=high*axis_steps_per_unit[E_AXIS]/(1000000.0); //so it is independent of the esteps/mm. before
float g=AUTOTEMP_MIN+high_e_speed*AUTOTEMP_FACTOR;
float t=constrain(AUTOTEMP_MIN,g,AUTOTEMP_MAX);
setTargetHotend0(t);
SERIAL_ECHO_START;
SERIAL_ECHOPAIR("highe",high_e_speed);
SERIAL_ECHOPAIR(" t",t);
SERIAL_ECHOLN("");
}
#endif
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();
}
float junction_deviation = 0.1;
// 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 = next_block_index(block_buffer_head);
// 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; };
// 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); }
//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_mm[4];
delta_mm[X_AXIS] = (target[X_AXIS]-position[X_AXIS])/axis_steps_per_unit[X_AXIS];
delta_mm[Y_AXIS] = (target[Y_AXIS]-position[Y_AXIS])/axis_steps_per_unit[Y_AXIS];
delta_mm[Z_AXIS] = (target[Z_AXIS]-position[Z_AXIS])/axis_steps_per_unit[Z_AXIS];
delta_mm[E_AXIS] = (target[E_AXIS]-position[E_AXIS])/axis_steps_per_unit[E_AXIS];
block->millimeters = sqrt(square(delta_mm[X_AXIS]) + square(delta_mm[Y_AXIS]) +
square(delta_mm[Z_AXIS]));
float inverse_millimeters = 1.0/block->millimeters; // Inverse millimeters to remove multiple divides
// Calculate speed in mm/second for each axis. No divide by zero due to previous checks.
float inverse_second = feed_rate * inverse_millimeters;
block->nominal_speed = block->millimeters * inverse_second; // (mm/sec) Always > 0
block->nominal_rate = ceil(block->step_event_count * inverse_second); // (step/sec) Always > 0
// unsigned long microseconds;
#if 0
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
#endif
// Calculate speed in mm/sec for each axis
float current_speed[4];
for(int i=0; i < 4; i++) {
current_speed[i] = delta_mm[i] * inverse_second;
}
// Limit speed per axis
float speed_factor = 1.0; //factor <=1 do decrease speed
for(int i=0; i < 4; i++) {
if(abs(current_speed[i]) > max_feedrate[i])
speed_factor = min(speed_factor, max_feedrate[i] / abs(current_speed[i]));
}
// Max segement time in us.
#ifdef XY_FREQUENCY_LIMIT
#define MAX_FREQ_TIME (1000000.0/XY_FREQUENCY_LIMIT)
// Check and limit the xy direction change frequency
unsigned char direction_change = block->direction_bits ^ old_direction_bits;
old_direction_bits = block->direction_bits;
long segment_time = lround(1000000.0/inverse_second);
if((direction_change & (1<<X_AXIS)) == 0) {
x_segment_time[0] += segment_time;
}
else {
x_segment_time[2] = x_segment_time[1];
x_segment_time[1] = x_segment_time[0];
x_segment_time[0] = segment_time;
}
if((direction_change & (1<<Y_AXIS)) == 0) {
y_segment_time[0] += segment_time;
}
else {
y_segment_time[2] = y_segment_time[1];
y_segment_time[1] = y_segment_time[0];
y_segment_time[0] = segment_time;
}
long max_x_segment_time = max(x_segment_time[0], max(x_segment_time[1], x_segment_time[2]));
long max_y_segment_time = max(y_segment_time[0], max(y_segment_time[1], y_segment_time[2]));
long min_xy_segment_time =min(max_x_segment_time, max_y_segment_time);
if(min_xy_segment_time < MAX_FREQ_TIME) speed_factor = min(speed_factor, (float)min_xy_segment_time / (float)MAX_FREQ_TIME);
#endif
// Correct the speed
if( speed_factor < 1.0) {
// Serial.print("speed factor : "); Serial.println(speed_factor);
for(int i=0; i < 4; i++) {
if(abs(current_speed[i]) > max_feedrate[i])
speed_factor = min(speed_factor, max_feedrate[i] / abs(current_speed[i]));
// Serial.print("current_speed"); Serial.print(i); Serial.print(" : "); Serial.println(current_speed[i]);
}
for(unsigned char i=0; i < 4; i++) {
current_speed[i] *= speed_factor;
}
block->nominal_speed *= speed_factor;
block->nominal_rate *= speed_factor;
}
// Compute and limit the acceleration rate for the trapezoid generator.
float steps_per_mm = block->step_event_count/block->millimeters;
if(block->steps_x == 0 && block->steps_y == 0 && block->steps_z == 0) {
block->acceleration_st = ceil(retract_acceleration * steps_per_mm); // convert to: acceleration steps/sec^2
}
else {
block->acceleration_st = ceil(acceleration * steps_per_mm); // convert to: acceleration steps/sec^2
// Limit acceleration per axis
if(((float)block->acceleration_st * (float)block->steps_x / (float)block->step_event_count) > axis_steps_per_sqr_second[X_AXIS])
block->acceleration_st = axis_steps_per_sqr_second[X_AXIS];
if(((float)block->acceleration_st * (float)block->steps_y / (float)block->step_event_count) > axis_steps_per_sqr_second[Y_AXIS])
block->acceleration_st = axis_steps_per_sqr_second[Y_AXIS];
if(((float)block->acceleration_st * (float)block->steps_e / (float)block->step_event_count) > axis_steps_per_sqr_second[E_AXIS])
block->acceleration_st = axis_steps_per_sqr_second[E_AXIS];
if(((float)block->acceleration_st * (float)block->steps_z / (float)block->step_event_count ) > axis_steps_per_sqr_second[Z_AXIS])
block->acceleration_st = axis_steps_per_sqr_second[Z_AXIS];
}
block->acceleration = block->acceleration_st / steps_per_mm;
block->acceleration_rate = (long)((float)block->acceleration_st * 8.388608);
#if 0 // Use old jerk for now
// Compute path unit vector
double unit_vec[3];
unit_vec[X_AXIS] = delta_mm[X_AXIS]*inverse_millimeters;
unit_vec[Y_AXIS] = delta_mm[Y_AXIS]*inverse_millimeters;
unit_vec[Z_AXIS] = delta_mm[Z_AXIS]*inverse_millimeters;
// Compute maximum allowable entry speed at junction by centripetal acceleration approximation.
// Let a circle be tangent to both previous and current path line segments, where the junction
// deviation is defined as the distance from the junction to the closest edge of the circle,
// colinear with the circle center. The circular segment joining the two paths represents the
// path of centripetal acceleration. Solve for max velocity based on max acceleration about the
// radius of the circle, defined indirectly by junction deviation. This may be also viewed as
// path width or max_jerk in the previous grbl version. This approach does not actually deviate
// from path, but used as a robust way to compute cornering speeds, as it takes into account the
// nonlinearities of both the junction angle and junction velocity.
double vmax_junction = MINIMUM_PLANNER_SPEED; // Set default max junction speed
// Skip first block or when previous_nominal_speed is used as a flag for homing and offset cycles.
if ((block_buffer_head != block_buffer_tail) && (previous_nominal_speed > 0.0)) {
// Compute cosine of angle between previous and current path. (prev_unit_vec is negative)
// NOTE: Max junction velocity is computed without sin() or acos() by trig half angle identity.
double cos_theta = - previous_unit_vec[X_AXIS] * unit_vec[X_AXIS]
- previous_unit_vec[Y_AXIS] * unit_vec[Y_AXIS]
- previous_unit_vec[Z_AXIS] * unit_vec[Z_AXIS] ;
// Skip and use default max junction speed for 0 degree acute junction.
if (cos_theta < 0.95) {
vmax_junction = min(previous_nominal_speed,block->nominal_speed);
// Skip and avoid divide by zero for straight junctions at 180 degrees. Limit to min() of nominal speeds.
if (cos_theta > -0.95) {
// Compute maximum junction velocity based on maximum acceleration and junction deviation
double sin_theta_d2 = sqrt(0.5*(1.0-cos_theta)); // Trig half angle identity. Always positive.
vmax_junction = min(vmax_junction,
sqrt(block->acceleration * junction_deviation * sin_theta_d2/(1.0-sin_theta_d2)) );
}
}
}
#endif
// Start with a safe speed
float vmax_junction = max_xy_jerk/2;
if(abs(current_speed[Z_AXIS]) > max_z_jerk/2)
vmax_junction = max_z_jerk/2;
vmax_junction = min(vmax_junction, block->nominal_speed);
if ((block_buffer_head != block_buffer_tail) && (previous_nominal_speed > 0.0)) {
float jerk = sqrt(pow((current_speed[X_AXIS]-previous_speed[X_AXIS]), 2)+pow((current_speed[Y_AXIS]-previous_speed[Y_AXIS]), 2));
if((previous_speed[X_AXIS] != 0.0) || (previous_speed[Y_AXIS] != 0.0)) {
vmax_junction = block->nominal_speed;
}
if (jerk > max_xy_jerk) {
vmax_junction *= (max_xy_jerk/jerk);
}
if(abs(current_speed[Z_AXIS] - previous_speed[Z_AXIS]) > max_z_jerk) {
vmax_junction *= (max_z_jerk/abs(current_speed[Z_AXIS] - previous_speed[Z_AXIS]));
}
}
block->max_entry_speed = vmax_junction;
// Initialize block entry speed. Compute based on deceleration to user-defined MINIMUM_PLANNER_SPEED.
double v_allowable = max_allowable_speed(-block->acceleration,MINIMUM_PLANNER_SPEED,block->millimeters);
block->entry_speed = min(vmax_junction, v_allowable);
// Initialize planner efficiency flags
// Set flag if block will always reach maximum junction speed regardless of entry/exit speeds.
// If a block can de/ac-celerate from nominal speed to zero within the length of the block, then
// the current block and next block junction speeds are guaranteed to always be at their maximum
// junction speeds in deceleration and acceleration, respectively. This is due to how the current
// block nominal speed limits both the current and next maximum junction speeds. Hence, in both
// the reverse and forward planners, the corresponding block junction speed will always be at the
// the maximum junction speed and may always be ignored for any speed reduction checks.
if (block->nominal_speed <= v_allowable) { block->nominal_length_flag = true; }
else { block->nominal_length_flag = false; }
block->recalculate_flag = true; // Always calculate trapezoid for new block
// Update previous path unit_vector and nominal speed
memcpy(previous_speed, current_speed, sizeof(previous_speed)); // previous_speed[] = current_speed[]
previous_nominal_speed = block->nominal_speed;
#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
calculate_trapezoid_for_block(block, block->entry_speed/block->nominal_speed,
MINIMUM_PLANNER_SPEED/block->nominal_speed);
// Move buffer head
block_buffer_head = next_buffer_head;
// Update position
memcpy(position, target, sizeof(target)); // position[] = target[]
planner_recalculate();
#ifdef AUTOTEMP
getHighESpeed();
#endif
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]);
previous_nominal_speed = 0.0; // Resets planner junction speeds. Assumes start from rest.
previous_speed[0] = 0.0;
previous_speed[1] = 0.0;
previous_speed[2] = 0.0;
previous_speed[3] = 0.0;
}
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