Diff: modules/robot/Planner.cpp

Revision:

0:31e91bb0ef3c

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/modules/robot/Planner.cpp	Tue Jul 31 21:11:18 2012 +0000
@@ -0,0 +1,264 @@
+/*  
+      This file is part of Smoothie (http://smoothieware.org/). The motion control part is heavily based on Grbl (https://github.com/simen/grbl) with additions from Sungeun K. Jeon (https://github.com/chamnit/grbl)
+      Smoothie 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.
+      Smoothie 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 Smoothie. If not, see <http://www.gnu.org/licenses/>. 
+*/
+
+using namespace std;
+#include <vector>
+#include "libs/nuts_bolts.h"
+#include "libs/RingBuffer.h"
+#include "../communication/utils/Gcode.h"
+#include "libs/Module.h"
+#include "libs/Kernel.h"
+#include "Block.h"
+#include "Planner.h"
+#include "Player.h" 
+
+
+Planner::Planner(){
+    clear_vector(this->position);
+    clear_vector_double(this->previous_unit_vec);
+    this->previous_nominal_speed = 0.0;
+    this->has_deleted_block = false;
+}
+
+void Planner::on_module_loaded(){
+    this->on_config_reload(this);
+}
+
+void Planner::on_config_reload(void* argument){
+    this->acceleration =       this->kernel->config->value(acceleration_checksum       )->by_default(100 )->as_number();
+    this->max_jerk =           this->kernel->config->value(max_jerk_checksum           )->by_default(100 )->as_number();
+    this->junction_deviation = this->kernel->config->value(junction_deviation_checksum )->by_default(0.05)->as_number(); 
+}
+
+
+// Append a block to the queue, compute it's speed factors
+void Planner::append_block( int target[], double feed_rate, double distance, double deltas[] ){
+   
+    // Stall here if the queue is ful
+    this->kernel->player->wait_for_queue(2);
+
+    Block* block = this->kernel->player->new_block();
+    block->planner = this;   
+
+    // Direction bits
+    block->direction_bits = 0; 
+    for( int stepper=ALPHA_STEPPER; stepper<=GAMMA_STEPPER; stepper++){ 
+        if( target[stepper] < position[stepper] ){ block->direction_bits |= (1<<stepper); } 
+    }
+    
+    // Number of steps for each stepper
+    for( int stepper=ALPHA_STEPPER; stepper<=GAMMA_STEPPER; stepper++){ block->steps[stepper] = labs(target[stepper] - this->position[stepper]); } 
+    
+    // Max number of steps, for all axes
+    block->steps_event_count = max( block->steps[ALPHA_STEPPER], max( block->steps[BETA_STEPPER], block->steps[GAMMA_STEPPER] ) );
+    //if( block->steps_event_count == 0 ){ this->computing = false; return; }
+
+    block->millimeters = distance;
+    double inverse_millimeters = 0; 
+    if( distance > 0 ){ inverse_millimeters = 1.0/distance; }
+
+    // Calculate speed in mm/minute for each axis. No divide by zero due to previous checks.
+    // NOTE: Minimum stepper speed is limited by MINIMUM_STEPS_PER_MINUTE in stepper.c
+    double inverse_minute = feed_rate * inverse_millimeters;
+    if( distance > 0 ){ 
+        block->nominal_speed = block->millimeters * inverse_minute;           // (mm/min) Always > 0
+        block->nominal_rate = ceil(block->steps_event_count * inverse_minute); // (step/min) Always > 0
+    }else{
+        block->nominal_speed = 0;
+        block->nominal_rate = 0;
+    }
+
+    //this->kernel->serial->printf("nom_speed: %f nom_rate: %u step_event_count: %u block->steps_z: %u \r\n", block->nominal_speed, block->nominal_rate, block->steps_event_count, block->steps[2]  );
+    
+    // Compute the acceleration rate for the trapezoid generator. Depending on the slope of the line
+    // average travel per step event changes. For a line along one axis the travel per step event
+    // is equal to the travel/step in the particular axis. For a 45 degree line the steppers of both
+    // axes might step for every step event. Travel per step event is then sqrt(travel_x^2+travel_y^2).
+    // To generate trapezoids with contant acceleration between blocks the rate_delta must be computed
+    // specifically for each line to compensate for this phenomenon:
+    // Convert universal acceleration for direction-dependent stepper rate change parameter
+    block->rate_delta = ceil( block->steps_event_count*inverse_millimeters * this->acceleration*60.0 / this->kernel->stepper->acceleration_ticks_per_second ); // (step/min/acceleration_tick)
+
+    // Compute path unit vector
+    double unit_vec[3];
+    unit_vec[X_AXIS] = deltas[X_AXIS]*inverse_millimeters;
+    unit_vec[Y_AXIS] = deltas[Y_AXIS]*inverse_millimeters;
+    unit_vec[Z_AXIS] = deltas[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
+
+    if (this->kernel->player->queue.size() > 1 && (this->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 = - this->previous_unit_vec[X_AXIS] * unit_vec[X_AXIS]
+                         - this->previous_unit_vec[Y_AXIS] * unit_vec[Y_AXIS]
+                         - this->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(this->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(this->acceleration*60*60 * this->junction_deviation * sin_theta_d2/(1.0-sin_theta_d2)) ); 
+        }
+      }
+    }
+    block->max_entry_speed = vmax_junction;
+   
+    // Initialize block entry speed. Compute based on deceleration to user-defined MINIMUM_PLANNER_SPEED.
+    double v_allowable = this->max_allowable_speed(-this->acceleration,0.0,block->millimeters); //TODO: Get from config
+    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(this->previous_unit_vec, unit_vec, sizeof(unit_vec)); // previous_unit_vec[] = unit_vec[]
+    this->previous_nominal_speed = block->nominal_speed;
+    
+    // Update current position
+    memcpy(this->position, target, sizeof(int)*3);
+
+    // Math-heavy re-computing of the whole queue to take the new 
+    this->recalculate();
+    
+    // The block can now be used 
+    block->ready();
+
+}
+
+
+// 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() {
+   //this->kernel->serial->printf("recalculate last: %p, queue size: %d \r\n", this->kernel->player->queue.get_ref( this->kernel->player->queue.size()-1  ), this->kernel->player->queue.size() );
+   this->reverse_pass();
+   this->forward_pass();
+   this->recalculate_trapezoids();
+}
+
+// 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(){
+    // For each block
+    int block_index = this->kernel->player->queue.tail;
+    Block* blocks[3] = {NULL,NULL,NULL};
+
+    while(block_index!=this->kernel->player->queue.head){
+        block_index = this->kernel->player->queue.prev_block_index( block_index );
+        blocks[2] = blocks[1];
+        blocks[1] = blocks[0];
+        blocks[0] = &this->kernel->player->queue.buffer[block_index];
+        if( blocks[1] == NULL ){ continue; }
+        blocks[1]->reverse_pass(blocks[2], blocks[0]);
+    }
+    
+}
+
+// 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() {
+    // For each block
+    int block_index = this->kernel->player->queue.head; 
+    Block* blocks[3] = {NULL,NULL,NULL};
+
+    while(block_index!=this->kernel->player->queue.tail){
+        blocks[0] = blocks[1];
+        blocks[1] = blocks[2];
+        blocks[2] = &this->kernel->player->queue.buffer[block_index];
+        if( blocks[0] == NULL ){ continue; }
+        blocks[1]->forward_pass(blocks[0],blocks[2]);
+        block_index = this->kernel->player->queue.next_block_index( block_index );
+    } 
+    blocks[2]->forward_pass(blocks[1],NULL);   
+
+}
+
+// Recalculates the trapezoid speed profiles for flagged blocks in the plan according to the
+// entry_speed for each junction and the entry_speed of the next junction. Must be called by
+// planner_recalculate() after updating the blocks. Any recalulate flagged junction will
+// compute the two adjacent trapezoids to the junction, since the junction speed corresponds
+// to exit speed and entry speed of one another.
+void Planner::recalculate_trapezoids() {
+    int block_index = this->kernel->player->queue.head;
+    Block* current;
+    Block* next = NULL;
+
+    while(block_index != this->kernel->player->queue.tail){
+        current = next;
+        next = &this->kernel->player->queue.buffer[block_index];
+        //this->kernel->serial->printf("index:%d current:%p next:%p \r\n", block_index, current, next );
+        if( current ){
+            // Recalculate if current block entry or exit junction speed has changed.
+            if( current->recalculate_flag || next->recalculate_flag ){
+                current->calculate_trapezoid( current->entry_speed/current->nominal_speed, next->entry_speed/current->nominal_speed );
+                current->recalculate_flag = false;
+            }
+        }
+        block_index = this->kernel->player->queue.next_block_index( block_index ); 
+    }
+
+    // Last/newest block in buffer. Exit speed is set with MINIMUM_PLANNER_SPEED. Always recalculated.
+    next->calculate_trapezoid( next->entry_speed/next->nominal_speed, MINIMUM_PLANNER_SPEED/next->nominal_speed); //TODO: Make configuration option
+    next->recalculate_flag = false;
+
+}
+
+// Debug function
+void Planner::dump_queue(){
+    for( int index = 0; index <= this->kernel->player->queue.size()-1; index++ ){
+       if( index > 10 && index < this->kernel->player->queue.size()-10 ){ continue; }
+       this->kernel->serial->printf("block %03d > ", index);
+       this->kernel->player->queue.get_ref(index)->debug(this->kernel); 
+    }
+}
+
+// Calculates the maximum allowable speed at this point when you must be able to reach target_velocity using the
+// acceleration within the allotted distance.
+double Planner::max_allowable_speed(double acceleration, double target_velocity, double distance) {
+  return(
+    sqrt(target_velocity*target_velocity-2L*acceleration*60*60*distance)  //Was acceleration*60*60*distance, in case this breaks, but here we prefer to use seconds instead of minutes
+  );
+}
+
+