src/modules/robot/Block.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).
   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 #include "libs/Module.h"
   9 #include "libs/Kernel.h"
  10 #include "libs/nuts_bolts.h"
  11 #include <math.h>
  12 #include <string>
  13 #include "Block.h"
  14 #include "Planner.h"
  15 #include "Conveyor.h"
  16 using std::string;
  17 #include <vector>
  18 #include "../communication/utils/Gcode.h"
  19
  20 // A block represents a movement, it's length for each stepper motor, and the corresponding acceleration curves.
  21 // It's stacked on a queue, and that queue is then executed in order, to move the motors.
  22 // Most of the accel math is also done in this class
  23 // And GCode objects for use in on_gcode_execute are also help in here
  24
  25 Block::Block()
  26 {
  27     clear();
  28 }
  29
  30 void Block::clear()
  31 {
  32     //commands.clear();
  33     //travel_distances.clear();
  34     gcodes.clear();
  35     clear_vector(this->steps);
  36
  37     steps_event_count   = 0;
  38     nominal_rate        = 0;
  39     nominal_speed       = 0.0F;
  40     millimeters         = 0.0F;
  41     entry_speed         = 0.0F;
  42     rate_delta          = 0.0F;
  43     initial_rate        = -1;
  44     final_rate          = -1;
  45     accelerate_until    = 0;
  46     decelerate_after    = 0;
  47     direction_bits      = 0;
  48     recalculate_flag    = false;
  49     nominal_length_flag = false;
  50     max_entry_speed     = 0.0F;
  51     is_ready            = false;
  52     times_taken         = 0;
  53 }
  54
  55 void Block::debug()
  56 {
  57     THEKERNEL->streams->printf("%p: steps:X%04d Y%04d Z%04d(max:%4d) nominal:r%10d/s%6.1f mm:%9.6f rdelta:%8f acc:%5d dec:%5d rates:%10d>%10d  entry/max: %10.4f/%10.4f taken:%d ready:%d recalc:%d nomlen:%d\r\n",
  58                                this,
  59                                          this->steps[0],
  60                                                this->steps[1],
  61                                                       this->steps[2],
  62                                                                this->steps_event_count,
  63                                                                              this->nominal_rate,
  64                                                                                    this->nominal_speed,
  65                                                                                             this->millimeters,
  66                                                                                                          this->rate_delta,
  67                                                                                                                  this->accelerate_until,
  68                                                                                                                          this->decelerate_after,
  69                                                                                                                                    this->initial_rate,
  70                                                                                                                                         this->final_rate,
  71                                                                                                                                                           this->entry_speed,
  72                                                                                                                                                                 this->max_entry_speed,
  73                                                                                                                                                                              this->times_taken,
  74                                                                                                                                                                                       this->is_ready,
  75                                                                                                                                                                                                 recalculate_flag?1:0,
  76                                                                                                                                                                                                           nominal_length_flag?1:0
  77                              );
  78 }
  79
  80
  81 /* Calculates trapezoid parameters so that the entry- and exit-speed is compensated by the provided factors.
  82 // The factors represent a factor of braking and must be in the range 0.0-1.0.
  83 //                                +--------+ <- nominal_rate
  84 //                               /          \
  85 // nominal_rate*entry_factor -> +            \
  86 //                              |             + <- nominal_rate*exit_factor
  87 //                              +-------------+
  88 //                                  time -->
  89 */
  90 void Block::calculate_trapezoid( float entryspeed, float exitspeed )
  91 {
  92     // if block is currently executing, don't touch anything!
  93     if (times_taken)
  94         return;
  95
  96     // The planner passes us factors, we need to transform them in rates
  97     this->initial_rate = ceil(this->nominal_rate * entryspeed / this->nominal_speed);   // (step/min)
  98     this->final_rate   = ceil(this->nominal_rate * exitspeed  / this->nominal_speed);   // (step/min)
  99
 100     // How many steps to accelerate and decelerate
 101     float acceleration_per_minute = this->rate_delta * THEKERNEL->stepper->acceleration_ticks_per_second * 60.0; // ( step/min^2)
 102     int accelerate_steps = ceil( this->estimate_acceleration_distance( this->initial_rate, this->nominal_rate, acceleration_per_minute ) );
 103     int decelerate_steps = floor( this->estimate_acceleration_distance( this->nominal_rate, this->final_rate,  -acceleration_per_minute ) );
 104
 105     // Calculate the size of Plateau of Nominal Rate ( during which we don't accelerate nor decelerate, but just cruise )
 106     int plateau_steps = this->steps_event_count - accelerate_steps - decelerate_steps;
 107
 108     // Is the Plateau of Nominal Rate smaller than nothing? That means no cruising, and we will
 109     // have to use intersection_distance() to calculate when to abort acceleration and start braking
 110     // in order to reach the final_rate exactly at the end of this block.
 111     if (plateau_steps < 0) {
 112         accelerate_steps = ceil(this->intersection_distance(this->initial_rate, this->final_rate, acceleration_per_minute, this->steps_event_count));
 113         accelerate_steps = max( accelerate_steps, 0 ); // Check limits due to numerical round-off
 114         accelerate_steps = min( accelerate_steps, int(this->steps_event_count) );
 115         plateau_steps = 0;
 116     }
 117     this->accelerate_until = accelerate_steps;
 118     this->decelerate_after = accelerate_steps + plateau_steps;
 119
 120     this->exit_speed = exitspeed;
 121 }
 122
 123 // Calculates the distance (not time) it takes to accelerate from initial_rate to target_rate using the
 124 // given acceleration:
 125 float Block::estimate_acceleration_distance(float initialrate, float targetrate, float acceleration)
 126 {
 127     return( ((targetrate * targetrate) - (initialrate * initialrate)) / (2.0F * acceleration));
 128 }
 129
 130 // This function gives you the point at which you must start braking (at the rate of -acceleration) if
 131 // you started at speed initial_rate and accelerated until this point and want to end at the final_rate after
 132 // a total travel of distance. This can be used to compute the intersection point between acceleration and
 133 // deceleration in the cases where the trapezoid has no plateau (i.e. never reaches maximum speed)
 134 //
 135 /*                          + <- some maximum rate we don't care about
 136                            /|\
 137                           / | \
 138                          /  |  + <- final_rate
 139                         /   |  |
 140        initial_rate -> +----+--+
 141                             ^ ^
 142                             | |
 143         intersection_distance distance */
 144 float Block::intersection_distance(float initialrate, float finalrate, float acceleration, float distance)
 145 {
 146     return((2 * acceleration * distance - initialrate * initialrate + finalrate * finalrate) / (4 * acceleration));
 147 }
 148
 149 // Calculates the maximum allowable speed at this point when you must be able to reach target_velocity using the
 150 // acceleration within the allotted distance.
 151 inline float max_allowable_speed(float acceleration, float target_velocity, float distance)
 152 {
 153     return sqrtf(target_velocity * target_velocity - 2.0F * acceleration * distance);
 154 }
 155
 156
 157 // Called by Planner::recalculate() when scanning the plan from last to first entry.
 158 float Block::reverse_pass(float exit_speed)
 159 {
 160     // If entry speed is already at the maximum entry speed, no need to recheck. Block is cruising.
 161     // If not, block in state of acceleration or deceleration. Reset entry speed to maximum and
 162     // check for maximum allowable speed reductions to ensure maximum possible planned speed.
 163     if (this->entry_speed != this->max_entry_speed)
 164     {
 165         // If nominal length true, max junction speed is guaranteed to be reached. Only compute
 166         // for max allowable speed if block is decelerating and nominal length is false.
 167         if ((!this->nominal_length_flag) && (this->max_entry_speed > exit_speed))
 168         {
 169             float max_entry_speed = max_allowable_speed(-THEKERNEL->planner->acceleration, exit_speed, this->millimeters);
 170
 171             this->entry_speed = min(max_entry_speed, this->max_entry_speed);
 172
 173             return this->entry_speed;
 174         }
 175         else
 176             this->entry_speed = this->max_entry_speed;
 177     }
 178
 179     return this->entry_speed;
 180 }
 181
 182
 183 // Called by Planner::recalculate() when scanning the plan from first to last entry.
 184 // returns maximum exit speed of this block
 185 float Block::forward_pass(float prev_max_exit_speed)
 186 {
 187     // If the previous block is an acceleration block, but it is not long enough to complete the
 188     // full speed change within the block, we need to adjust the entry speed accordingly. Entry
 189     // speeds have already been reset, maximized, and reverse planned by reverse planner.
 190     // If nominal length is true, max junction speed is guaranteed to be reached. No need to recheck.
 191
 192     // TODO: find out if both of these checks are necessary
 193     if (prev_max_exit_speed > nominal_speed)
 194         prev_max_exit_speed = nominal_speed;
 195     if (prev_max_exit_speed > max_entry_speed)
 196         prev_max_exit_speed = max_entry_speed;
 197
 198     if (prev_max_exit_speed <= entry_speed)
 199     {
 200         // accel limited
 201         entry_speed = prev_max_exit_speed;
 202         // since we're now acceleration or cruise limited
 203         // we don't need to recalculate our entry speed anymore
 204         recalculate_flag = false;
 205     }
 206     // else
 207     // // decel limited, do nothing
 208
 209     return max_exit_speed();
 210 }
 211
 212 float Block::max_exit_speed()
 213 {
 214     // if block is currently executing, return cached exit speed from calculate_trapezoid
 215     // this ensures that a block following a currently executing block will have correct entry speed
 216     if (times_taken)
 217         return exit_speed;
 218
 219     // if nominal_length_flag is asserted
 220     // we are guaranteed to reach nominal speed regardless of entry speed
 221     // thus, max exit will always be nominal
 222     if (nominal_length_flag)
 223         return nominal_speed;
 224
 225     // otherwise, we have to work out max exit speed based on entry and acceleration
 226     float max = max_allowable_speed(-THEKERNEL->planner->acceleration, this->entry_speed, this->millimeters);
 227
 228     return min(max, nominal_speed);
 229 }
 230
 231 // Gcodes are attached to their respective blocks so that on_gcode_execute can be called with it
 232 void Block::append_gcode(Gcode* gcode)
 233 {
 234     Gcode new_gcode = *gcode;
 235     gcodes.push_back(new_gcode);
 236 }
 237
 238 void Block::begin()
 239 {
 240     recalculate_flag = false;
 241
 242     times_taken = -1;
 243
 244     // execute all the gcodes related to this block
 245     for(unsigned int index = 0; index < gcodes.size(); index++)
 246         THEKERNEL->call_event(ON_GCODE_EXECUTE, &(gcodes[index]));
 247
 248     THEKERNEL->call_event(ON_BLOCK_BEGIN, this);
 249
 250     if (times_taken < 0)
 251         release();
 252 }
 253
 254 // Signal the conveyor that this block is ready to be injected into the system
 255 void Block::ready()
 256 {
 257     this->is_ready = true;
 258 }
 259
 260 // Mark the block as taken by one more module
 261 void Block::take()
 262 {
 263     if (times_taken < 0)
 264         times_taken = 0;
 265     times_taken++;
 266 }
 267
 268 // Mark the block as no longer taken by one module, go to next block if this free's it
 269 void Block::release()
 270 {
 271     if (--this->times_taken <= 0)
 272     {
 273         THEKERNEL->call_event(ON_BLOCK_END, this);
 274
 275         // ensure conveyor gets called last
 276         THEKERNEL->conveyor->on_block_end(this);
 277     }
 278 }