src/modules/robot/Planner.cpp

   1 /*
   2       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)
   3       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.
   4       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.
   5       You should have received a copy of the GNU General Public License along with Smoothie. If not, see <http://www.gnu.org/licenses/>.
   6 */
   7
   8 using namespace std;
   9 #include <vector>
  10 #include "libs/nuts_bolts.h"
  11 #include "libs/RingBuffer.h"
  12 #include "../communication/utils/Gcode.h"
  13 #include "libs/Module.h"
  14 #include "libs/Kernel.h"
  15 #include "Block.h"
  16 #include "Planner.h"
  17 #include "Conveyor.h"
  18
  19
  20 Planner::Planner(){
  21     clear_vector(this->position);
  22     clear_vector_double(this->previous_unit_vec);
  23     this->previous_nominal_speed = 0.0;
  24     this->has_deleted_block = false;
  25 }
  26
  27 void Planner::on_module_loaded(){
  28     this->on_config_reload(this);
  29 }
  30
  31 void Planner::on_config_reload(void* argument){
  32     this->acceleration =       this->kernel->config->value(acceleration_checksum       )->by_default(100 )->as_number() * 60 * 60; // Acceleration is in mm/minute^2, see https://github.com/grbl/grbl/commit/9141ad282540eaa50a41283685f901f29c24ddbd#planner.c
  33     this->max_jerk =           this->kernel->config->value(max_jerk_checksum           )->by_default(100 )->as_number();
  34     this->junction_deviation = this->kernel->config->value(junction_deviation_checksum )->by_default(0.05)->as_number();
  35 }
  36
  37
  38 // Append a block to the queue, compute it's speed factors
  39 void Planner::append_block( int target[], double feed_rate, double distance, double deltas[] ){
  40
  41     //printf("new block\r\n");
  42
  43     // Stall here if the queue is ful
  44     this->kernel->conveyor->wait_for_queue(2);
  45
  46     Block* block = this->kernel->conveyor->new_block();
  47     block->planner = this;
  48
  49     // Direction bits
  50     block->direction_bits = 0;
  51     for( int stepper=ALPHA_STEPPER; stepper<=GAMMA_STEPPER; stepper++){
  52         if( target[stepper] < position[stepper] ){ block->direction_bits |= (1<<stepper); }
  53     }
  54
  55     // Number of steps for each stepper
  56     for( int stepper=ALPHA_STEPPER; stepper<=GAMMA_STEPPER; stepper++){ block->steps[stepper] = labs(target[stepper] - this->position[stepper]); }
  57
  58     // Max number of steps, for all axes
  59     block->steps_event_count = max( block->steps[ALPHA_STEPPER], max( block->steps[BETA_STEPPER], block->steps[GAMMA_STEPPER] ) );
  60     //if( block->steps_event_count == 0 ){ this->computing = false; return; }
  61
  62     block->millimeters = distance;
  63     double inverse_millimeters = 0;
  64     if( distance > 0 ){ inverse_millimeters = 1.0/distance; }
  65
  66     // Calculate speed in mm/minute for each axis. No divide by zero due to previous checks.
  67     // NOTE: Minimum stepper speed is limited by MINIMUM_STEPS_PER_MINUTE in stepper.c
  68     double inverse_minute = feed_rate * inverse_millimeters;
  69     if( distance > 0 ){
  70         block->nominal_speed = block->millimeters * inverse_minute;           // (mm/min) Always > 0
  71         block->nominal_rate = ceil(block->steps_event_count * inverse_minute); // (step/min) Always > 0
  72     }else{
  73         block->nominal_speed = 0;
  74         block->nominal_rate = 0;
  75     }
  76
  77     //this->kernel->streams->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]  );
  78
  79     // Compute the acceleration rate for the trapezoid generator. Depending on the slope of the line
  80     // average travel per step event changes. For a line along one axis the travel per step event
  81     // is equal to the travel/step in the particular axis. For a 45 degree line the steppers of both
  82     // axes might step for every step event. Travel per step event is then sqrt(travel_x^2+travel_y^2).
  83     // To generate trapezoids with contant acceleration between blocks the rate_delta must be computed
  84     // specifically for each line to compensate for this phenomenon:
  85     // Convert universal acceleration for direction-dependent stepper rate change parameter
  86     block->rate_delta = (float)( ( block->steps_event_count*inverse_millimeters * this->acceleration ) / ( this->kernel->stepper->acceleration_ticks_per_second * 60 ) ); // (step/min/acceleration_tick)
  87
  88
  89     // Compute path unit vector
  90     double unit_vec[3];
  91     unit_vec[X_AXIS] = deltas[X_AXIS]*inverse_millimeters;
  92     unit_vec[Y_AXIS] = deltas[Y_AXIS]*inverse_millimeters;
  93     unit_vec[Z_AXIS] = deltas[Z_AXIS]*inverse_millimeters;
  94
  95     // Compute maximum allowable entry speed at junction by centripetal acceleration approximation.
  96     // Let a circle be tangent to both previous and current path line segments, where the junction
  97     // deviation is defined as the distance from the junction to the closest edge of the circle,
  98     // colinear with the circle center. The circular segment joining the two paths represents the
  99     // path of centripetal acceleration. Solve for max velocity based on max acceleration about the
 100     // radius of the circle, defined indirectly by junction deviation. This may be also viewed as
 101     // path width or max_jerk in the previous grbl version. This approach does not actually deviate
 102     // from path, but used as a robust way to compute cornering speeds, as it takes into account the
 103     // nonlinearities of both the junction angle and junction velocity.
 104     double vmax_junction = MINIMUM_PLANNER_SPEED; // Set default max junction speed
 105
 106     if (this->kernel->conveyor->queue.size() > 1 && (this->previous_nominal_speed > 0.0)) {
 107       // Compute cosine of angle between previous and current path. (prev_unit_vec is negative)
 108       // NOTE: Max junction velocity is computed without sin() or acos() by trig half angle identity.
 109       double cos_theta = - this->previous_unit_vec[X_AXIS] * unit_vec[X_AXIS]
 110                          - this->previous_unit_vec[Y_AXIS] * unit_vec[Y_AXIS]
 111                          - this->previous_unit_vec[Z_AXIS] * unit_vec[Z_AXIS] ;
 112
 113       // Skip and use default max junction speed for 0 degree acute junction.
 114       if (cos_theta < 0.95) {
 115         vmax_junction = min(this->previous_nominal_speed,block->nominal_speed);
 116         // Skip and avoid divide by zero for straight junctions at 180 degrees. Limit to min() of nominal speeds.
 117         if (cos_theta > -0.95) {
 118           // Compute maximum junction velocity based on maximum acceleration and junction deviation
 119           double sin_theta_d2 = sqrt(0.5*(1.0-cos_theta)); // Trig half angle identity. Always positive.
 120           vmax_junction = min(vmax_junction,
 121             sqrt(this->acceleration * this->junction_deviation * sin_theta_d2/(1.0-sin_theta_d2)) );
 122         }
 123       }
 124     }
 125     block->max_entry_speed = vmax_junction;
 126
 127     // Initialize block entry speed. Compute based on deceleration to user-defined MINIMUM_PLANNER_SPEED.
 128     double v_allowable = this->max_allowable_speed(-this->acceleration,0.0,block->millimeters); //TODO: Get from config
 129     block->entry_speed = min(vmax_junction, v_allowable);
 130
 131     // Initialize planner efficiency flags
 132     // Set flag if block will always reach maximum junction speed regardless of entry/exit speeds.
 133     // If a block can de/ac-celerate from nominal speed to zero within the length of the block, then
 134     // the current block and next block junction speeds are guaranteed to always be at their maximum
 135     // junction speeds in deceleration and acceleration, respectively. This is due to how the current
 136     // block nominal speed limits both the current and next maximum junction speeds. Hence, in both
 137     // the reverse and forward planners, the corresponding block junction speed will always be at the
 138     // the maximum junction speed and may always be ignored for any speed reduction checks.
 139     if (block->nominal_speed <= v_allowable) { block->nominal_length_flag = true; }
 140     else { block->nominal_length_flag = false; }
 141     block->recalculate_flag = true; // Always calculate trapezoid for new block
 142
 143     // Update previous path unit_vector and nominal speed
 144     memcpy(this->previous_unit_vec, unit_vec, sizeof(unit_vec)); // previous_unit_vec[] = unit_vec[]
 145     this->previous_nominal_speed = block->nominal_speed;
 146
 147     // Update current position
 148     memcpy(this->position, target, sizeof(int)*3);
 149
 150     // Math-heavy re-computing of the whole queue to take the new
 151     this->recalculate();
 152
 153     // The block can now be used
 154     block->ready();
 155
 156 }
 157
 158
 159 // Recalculates the motion plan according to the following algorithm:
 160 //
 161 // 1. Go over every block in reverse order and calculate a junction speed reduction (i.e. block_t.entry_factor)
 162 // so that:
 163 //   a. The junction jerk is within the set limit
 164 //   b. No speed reduction within one block requires faster deceleration than the one, true constant
 165 //      acceleration.
 166 // 2. Go over every block in chronological order and dial down junction speed reduction values if
 167 //   a. The speed increase within one block would require faster accelleration than the one, true
 168 //      constant acceleration.
 169 //
 170 // When these stages are complete all blocks have an entry_factor that will allow all speed changes to
 171 // be performed using only the one, true constant acceleration, and where no junction jerk is jerkier than
 172 // the set limit. Finally it will:
 173 //
 174 // 3. Recalculate trapezoids for all blocks.
 175 //
 176 void Planner::recalculate() {
 177    //this->kernel->streams->printf("recalculate last: %p, queue size: %d \r\n", this->kernel->conveyor->queue.get_ref( this->kernel->conveyor->queue.size()-1  ), this->kernel->conveyor->queue.size() );
 178    this->reverse_pass();
 179    this->forward_pass();
 180    this->recalculate_trapezoids();
 181 }
 182
 183 // Planner::recalculate() needs to go over the current plan twice. Once in reverse and once forward. This
 184 // implements the reverse pass.
 185 void Planner::reverse_pass(){
 186     // For each block
 187     int block_index = this->kernel->conveyor->queue.tail;
 188     Block* blocks[3] = {NULL,NULL,NULL};
 189
 190     while(block_index!=this->kernel->conveyor->queue.head){
 191         block_index = this->kernel->conveyor->queue.prev_block_index( block_index );
 192         blocks[2] = blocks[1];
 193         blocks[1] = blocks[0];
 194         blocks[0] = &this->kernel->conveyor->queue.buffer[block_index];
 195         if( blocks[1] == NULL ){ continue; }
 196         blocks[1]->reverse_pass(blocks[2], blocks[0]);
 197     }
 198
 199 }
 200
 201 // Planner::recalculate() needs to go over the current plan twice. Once in reverse and once forward. This
 202 // implements the forward pass.
 203 void Planner::forward_pass() {
 204     // For each block
 205     int block_index = this->kernel->conveyor->queue.head;
 206     Block* blocks[3] = {NULL,NULL,NULL};
 207
 208     while(block_index!=this->kernel->conveyor->queue.tail){
 209         blocks[0] = blocks[1];
 210         blocks[1] = blocks[2];
 211         blocks[2] = &this->kernel->conveyor->queue.buffer[block_index];
 212         if( blocks[0] == NULL ){ continue; }
 213         blocks[1]->forward_pass(blocks[0],blocks[2]);
 214         block_index = this->kernel->conveyor->queue.next_block_index( block_index );
 215     }
 216     blocks[2]->forward_pass(blocks[1],NULL);
 217
 218 }
 219
 220 // Recalculates the trapezoid speed profiles for flagged blocks in the plan according to the
 221 // entry_speed for each junction and the entry_speed of the next junction. Must be called by
 222 // planner_recalculate() after updating the blocks. Any recalulate flagged junction will
 223 // compute the two adjacent trapezoids to the junction, since the junction speed corresponds
 224 // to exit speed and entry speed of one another.
 225 void Planner::recalculate_trapezoids() {
 226     int block_index = this->kernel->conveyor->queue.head;
 227     Block* current;
 228     Block* next = NULL;
 229
 230     while(block_index != this->kernel->conveyor->queue.tail){
 231         current = next;
 232         next = &this->kernel->conveyor->queue.buffer[block_index];
 233         //this->kernel->streams->printf("index:%d current:%p next:%p \r\n", block_index, current, next );
 234         if( current ){
 235             // Recalculate if current block entry or exit junction speed has changed.
 236             if( current->recalculate_flag || next->recalculate_flag ){
 237                 current->calculate_trapezoid( current->entry_speed/current->nominal_speed, next->entry_speed/current->nominal_speed );
 238                 current->recalculate_flag = false;
 239             }
 240         }
 241         block_index = this->kernel->conveyor->queue.next_block_index( block_index );
 242     }
 243
 244     // Last/newest block in buffer. Exit speed is set with MINIMUM_PLANNER_SPEED. Always recalculated.
 245     next->calculate_trapezoid( next->entry_speed/next->nominal_speed, MINIMUM_PLANNER_SPEED/next->nominal_speed); //TODO: Make configuration option
 246     next->recalculate_flag = false;
 247
 248 }
 249
 250 // Debug function
 251 void Planner::dump_queue(){
 252     for( int index = 0; index <= this->kernel->conveyor->queue.size()-1; index++ ){
 253        if( index > 10 && index < this->kernel->conveyor->queue.size()-10 ){ continue; }
 254        this->kernel->streams->printf("block %03d > ", index);
 255        this->kernel->conveyor->queue.get_ref(index)->debug(this->kernel);
 256     }
 257 }
 258
 259 // Calculates the maximum allowable speed at this point when you must be able to reach target_velocity using the
 260 // acceleration within the allotted distance.
 261 double Planner::max_allowable_speed(double acceleration, double target_velocity, double distance) {
 262   return(
 263     //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
 264     sqrt(target_velocity*target_velocity-2L*acceleration*distance)  //Was acceleration*60*60*distance, in case this breaks, but here we prefer to use seconds instead of minutes
 265   );
 266 }
 267
 268