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 "mbed.h"
  11 #include "libs/nuts_bolts.h"
  12 #include "libs/RingBuffer.h"
  13 #include "../communication/utils/Gcode.h"
  14 #include "libs/Module.h"
  15 #include "libs/Kernel.h"
  16 #include "Block.h"
  17 #include "Planner.h"
  18 #include "Player.h"
  19
  20
  21 Planner::Planner(){
  22     clear_vector(this->position);
  23     clear_vector_double(this->previous_unit_vec);
  24     this->previous_nominal_speed = 0.0;
  25     this->has_deleted_block = false;
  26 }
  27
  28 void Planner::on_module_loaded(){
  29     this->on_config_reload(this);
  30 }
  31
  32 void Planner::on_config_reload(void* argument){
  33     this->acceleration =       this->kernel->config->value(acceleration_checksum       )->required()->as_number();
  34     this->max_jerk =           this->kernel->config->value(max_jerk_checksum           )->required(      )->as_number();
  35     this->junction_deviation = this->kernel->config->value(junction_deviation_checksum )->by_default(0.05)->as_number();
  36 }
  37
  38
  39 // Append a block to the queue, compute it's speed factors
  40 void Planner::append_block( int target[], double feed_rate, double distance, double deltas[] ){
  41
  42     // Do not append block with no movement
  43     //if( target[ALPHA_STEPPER] == this->position[ALPHA_STEPPER] && target[BETA_STEPPER] == this->position[BETA_STEPPER] && target[GAMMA_STEPPER] == this->position[GAMMA_STEPPER] ){ this->computing = false; return; }
  44
  45     // Stall here if the queue is ful
  46     while( this->kernel->player->queue.size() >= this->kernel->player->queue.capacity()-2 ){ wait_us(100); }
  47
  48     Block* block = this->kernel->player->new_block();
  49     block->planner = this;
  50
  51     // Direction bits
  52     block->direction_bits = 0;
  53     char direction_bits[3] = {this->kernel->stepper->alpha_dir_pin, this->kernel->stepper->beta_dir_pin, this->kernel->stepper->gamma_dir_pin};
  54     for( int stepper=ALPHA_STEPPER; stepper<=GAMMA_STEPPER; stepper++){
  55         if( target[stepper] < position[stepper] ){ block->direction_bits |= (1<<direction_bits[stepper]); }
  56     }
  57
  58     // Number of steps for each stepper
  59     for( int stepper=ALPHA_STEPPER; stepper<=GAMMA_STEPPER; stepper++){ block->steps[stepper] = labs(target[stepper] - this->position[stepper]); }
  60
  61     // Max number of steps, for all axes
  62     block->steps_event_count = max( block->steps[ALPHA_STEPPER], max( block->steps[BETA_STEPPER], block->steps[GAMMA_STEPPER] ) );
  63     //if( block->steps_event_count == 0 ){ this->computing = false; return; }
  64
  65     block->millimeters = distance;
  66     double inverse_millimeters = 0;
  67     if( distance > 0 ){ inverse_millimeters = 1.0/distance; }
  68
  69     // Calculate speed in mm/minute for each axis. No divide by zero due to previous checks.
  70     // NOTE: Minimum stepper speed is limited by MINIMUM_STEPS_PER_MINUTE in stepper.c
  71     double inverse_minute = feed_rate * inverse_millimeters;
  72     if( distance > 0 ){
  73         block->nominal_speed = block->millimeters * inverse_minute;           // (mm/min) Always > 0
  74         block->nominal_rate = ceil(block->steps_event_count * inverse_minute); // (step/min) Always > 0
  75     }else{
  76         block->nominal_speed = 0;
  77         block->nominal_rate = 0;
  78     }
  79
  80     //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]  );
  81
  82     // Compute the acceleration rate for the trapezoid generator. Depending on the slope of the line
  83     // average travel per step event changes. For a line along one axis the travel per step event
  84     // is equal to the travel/step in the particular axis. For a 45 degree line the steppers of both
  85     // axes might step for every step event. Travel per step event is then sqrt(travel_x^2+travel_y^2).
  86     // To generate trapezoids with contant acceleration between blocks the rate_delta must be computed
  87     // specifically for each line to compensate for this phenomenon:
  88     // Convert universal acceleration for direction-dependent stepper rate change parameter
  89     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)
  90
  91     // Compute path unit vector
  92     double unit_vec[3];
  93     unit_vec[X_AXIS] = deltas[X_AXIS]*inverse_millimeters;
  94     unit_vec[Y_AXIS] = deltas[Y_AXIS]*inverse_millimeters;
  95     unit_vec[Z_AXIS] = deltas[Z_AXIS]*inverse_millimeters;
  96
  97     // Compute maximum allowable entry speed at junction by centripetal acceleration approximation.
  98     // Let a circle be tangent to both previous and current path line segments, where the junction
  99     // deviation is defined as the distance from the junction to the closest edge of the circle,
 100     // colinear with the circle center. The circular segment joining the two paths represents the
 101     // path of centripetal acceleration. Solve for max velocity based on max acceleration about the
 102     // radius of the circle, defined indirectly by junction deviation. This may be also viewed as
 103     // path width or max_jerk in the previous grbl version. This approach does not actually deviate
 104     // from path, but used as a robust way to compute cornering speeds, as it takes into account the
 105     // nonlinearities of both the junction angle and junction velocity.
 106     double vmax_junction = MINIMUM_PLANNER_SPEED; // Set default max junction speed
 107
 108     if (this->kernel->player->queue.size() > 1 && (this->previous_nominal_speed > 0.0)) {
 109       // Compute cosine of angle between previous and current path. (prev_unit_vec is negative)
 110       // NOTE: Max junction velocity is computed without sin() or acos() by trig half angle identity.
 111       double cos_theta = - this->previous_unit_vec[X_AXIS] * unit_vec[X_AXIS]
 112                          - this->previous_unit_vec[Y_AXIS] * unit_vec[Y_AXIS]
 113                          - this->previous_unit_vec[Z_AXIS] * unit_vec[Z_AXIS] ;
 114
 115       // Skip and use default max junction speed for 0 degree acute junction.
 116       if (cos_theta < 0.95) {
 117         vmax_junction = min(this->previous_nominal_speed,block->nominal_speed);
 118         // Skip and avoid divide by zero for straight junctions at 180 degrees. Limit to min() of nominal speeds.
 119         if (cos_theta > -0.95) {
 120           // Compute maximum junction velocity based on maximum acceleration and junction deviation
 121           double sin_theta_d2 = sqrt(0.5*(1.0-cos_theta)); // Trig half angle identity. Always positive.
 122           vmax_junction = min(vmax_junction,
 123             sqrt(this->acceleration*60*60 * this->junction_deviation * sin_theta_d2/(1.0-sin_theta_d2)) );
 124         }
 125       }
 126     }
 127     block->max_entry_speed = vmax_junction;
 128
 129     // Initialize block entry speed. Compute based on deceleration to user-defined MINIMUM_PLANNER_SPEED.
 130     double v_allowable = this->max_allowable_speed(-this->acceleration,0.0,block->millimeters); //TODO: Get from config
 131     block->entry_speed = min(vmax_junction, v_allowable);
 132
 133     // Initialize planner efficiency flags
 134     // Set flag if block will always reach maximum junction speed regardless of entry/exit speeds.
 135     // If a block can de/ac-celerate from nominal speed to zero within the length of the block, then
 136     // the current block and next block junction speeds are guaranteed to always be at their maximum
 137     // junction speeds in deceleration and acceleration, respectively. This is due to how the current
 138     // block nominal speed limits both the current and next maximum junction speeds. Hence, in both
 139     // the reverse and forward planners, the corresponding block junction speed will always be at the
 140     // the maximum junction speed and may always be ignored for any speed reduction checks.
 141     if (block->nominal_speed <= v_allowable) { block->nominal_length_flag = true; }
 142     else { block->nominal_length_flag = false; }
 143     block->recalculate_flag = true; // Always calculate trapezoid for new block
 144
 145     // Update previous path unit_vector and nominal speed
 146     memcpy(this->previous_unit_vec, unit_vec, sizeof(unit_vec)); // previous_unit_vec[] = unit_vec[]
 147     this->previous_nominal_speed = block->nominal_speed;
 148
 149     // Update current position
 150     memcpy(this->position, target, sizeof(int)*3);
 151
 152     // Math-heavy re-computing of the whole queue to take the new
 153     this->recalculate();
 154
 155     // The block can now be used
 156     block->ready();
 157
 158 }
 159
 160
 161 // Recalculates the motion plan according to the following algorithm:
 162 //
 163 // 1. Go over every block in reverse order and calculate a junction speed reduction (i.e. block_t.entry_factor)
 164 // so that:
 165 //   a. The junction jerk is within the set limit
 166 //   b. No speed reduction within one block requires faster deceleration than the one, true constant
 167 //      acceleration.
 168 // 2. Go over every block in chronological order and dial down junction speed reduction values if
 169 //   a. The speed increase within one block would require faster accelleration than the one, true
 170 //      constant acceleration.
 171 //
 172 // When these stages are complete all blocks have an entry_factor that will allow all speed changes to
 173 // be performed using only the one, true constant acceleration, and where no junction jerk is jerkier than
 174 // the set limit. Finally it will:
 175 //
 176 // 3. Recalculate trapezoids for all blocks.
 177 //
 178 void Planner::recalculate() {
 179    //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() );
 180    this->reverse_pass();
 181    this->forward_pass();
 182    this->recalculate_trapezoids();
 183 }
 184
 185 // Planner::recalculate() needs to go over the current plan twice. Once in reverse and once forward. This
 186 // implements the reverse pass.
 187 void Planner::reverse_pass(){
 188      // For each block
 189     for( int index = this->kernel->player->queue.size()-1; index > 0; index-- ){  // Skip buffer tail/first block to prevent over-writing the initial entry speed.
 190         this->kernel->player->queue.get_ref(index)->reverse_pass((index==this->kernel->player->queue.size()-1?NULL:this->kernel->player->queue.get_ref(index+1)), (index==0? (this->has_deleted_block?&(this->last_deleted_block):NULL) :this->kernel->player->queue.get_ref(index-1)));
 191     }
 192 }
 193
 194 // Planner::recalculate() needs to go over the current plan twice. Once in reverse and once forward. This
 195 // implements the forward pass.
 196 void Planner::forward_pass() {
 197     // For each block
 198     for( int index = 0; index <= this->kernel->player->queue.size()-1; index++ ){
 199         this->kernel->player->queue.get_ref(index)->forward_pass((index==0?NULL:this->kernel->player->queue.get_ref(index-1)),(index==this->kernel->player->queue.size()-1?NULL:this->kernel->player->queue.get_ref(index+1)));
 200     }
 201 }
 202
 203 // Recalculates the trapezoid speed profiles for flagged blocks in the plan according to the
 204 // entry_speed for each junction and the entry_speed of the next junction. Must be called by
 205 // planner_recalculate() after updating the blocks. Any recalulate flagged junction will
 206 // compute the two adjacent trapezoids to the junction, since the junction speed corresponds
 207 // to exit speed and entry speed of one another.
 208 /*
 209 void Planner::recalculate_trapezoids() {
 210     // For each block
 211     int size = this->kernel->player->queue.size();
 212     for( int index = 0; index <= size-1; index++ ){ // We skip the first one because we need a previous
 213         if( size-1 == index ){ //last block
 214             Block* last = this->kernel->player->queue.get_ref(index);
 215             last->calculate_trapezoid( last->entry_speed / last->nominal_speed, MINIMUM_PLANNER_SPEED / last->nominal_speed );
 216             this->kernel->serial->printf("%p: %d/%d last r:%d \r\n", last, index, size-1,  last->initial_rate);
 217         }else{
 218             Block* current = this->kernel->player->queue.get_ref(index);
 219             Block* next =    this->kernel->player->queue.get_ref(index+1);
 220             if( current->recalculate_flag || next->recalculate_flag ){
 221                 current->calculate_trapezoid( current->entry_speed/current->nominal_speed, next->entry_speed/current->nominal_speed );
 222                 current->recalculate_flag = false; // Reset current only to ensure next trapezoid is computed
 223                 this->kernel->serial->printf("%p: %d/%d other r:%d \r\n", current, index, size-1, current->initial_rate);
 224             }else{
 225                 this->kernel->serial->printf("%p: %d/%d else r:%d \r\n", current, index, size-1, current->initial_rate);
 226             }
 227         }
 228     }
 229 }
 230 */
 231 void Planner::recalculate_trapezoids() {
 232     int block_index = this->kernel->player->queue.head;
 233     Block* current;
 234     Block* next = NULL;
 235
 236     //this->kernel->serial->printf("tail:%d head:%d size:%d\r\n", this->kernel->player->queue.tail, this->kernel->player->queue.head, this->kernel->player->queue.size());
 237
 238     while(block_index != this->kernel->player->queue.tail){
 239         current = next;
 240         next = &this->kernel->player->queue.buffer[block_index];
 241         //this->kernel->serial->printf("index:%d current:%p next:%p \r\n", block_index, current, next );
 242         if( current ){
 243             // Recalculate if current block entry or exit junction speed has changed.
 244             if( current->recalculate_flag || next->recalculate_flag ){
 245                 current->calculate_trapezoid( current->entry_speed/current->nominal_speed, next->entry_speed/current->nominal_speed );
 246                 current->recalculate_flag = false;
 247             }
 248         }
 249         block_index = this->kernel->player->queue.next_block_index( block_index );
 250     }
 251
 252     // Last/newest block in buffer. Exit speed is set with MINIMUM_PLANNER_SPEED. Always recalculated.
 253     next->calculate_trapezoid( next->entry_speed/next->nominal_speed, MINIMUM_PLANNER_SPEED/next->nominal_speed); //TODO: Make configuration option
 254     next->recalculate_flag = false;
 255
 256 }
 257
 258 // Debug function
 259 void Planner::dump_queue(){
 260     for( int index = 0; index <= this->kernel->player->queue.size()-1; index++ ){
 261        if( index > 10 && index < this->kernel->player->queue.size()-10 ){ continue; }
 262        this->kernel->serial->printf("block %03d > ", index);
 263        this->kernel->player->queue.get_ref(index)->debug(this->kernel);
 264     }
 265 }
 266
 267 // Calculates the maximum allowable speed at this point when you must be able to reach target_velocity using the
 268 // acceleration within the allotted distance.
 269 double Planner::max_allowable_speed(double acceleration, double target_velocity, double distance) {
 270   return(
 271     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
 272   );
 273 }
 274
 275