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 "mbed.h"
  13 #include <string>
  14 #include "Block.h"
  15 #include "Planner.h"
  16 using std::string;
  17 #include <vector>
  18 #include "../communication/utils/Gcode.h"
  19
  20
  21 Block::Block(){
  22     clear_vector(this->steps);
  23     this->computed = false;
  24 }
  25
  26 void Block::debug(Kernel* kernel){
  27     kernel->serial->printf(" steps:%4d|%4d|%4d(max:%4d) nominal:r%10d/s%6.1f mm:%9.6f rdelta:%8d acc:%5d dec:%5d rates:%10d>%10d \r\n", this->steps[0], this->steps[1], this->steps[2], this->steps_event_count, this->nominal_rate, this->nominal_speed, this->millimeters, this->rate_delta, this->accelerate_until, this->decelerate_after, this->initial_rate, this->final_rate );
  28 }
  29
  30
  31 // Calculate a braking factor to reach baseline speed which is max_jerk/2, e.g. the
  32 // speed under which you cannot exceed max_jerk no matter what you do.
  33 double Block::compute_factor_for_safe_speed(){
  34     return( this->planner->max_jerk / this->nominal_speed );
  35 }
  36
  37
  38 // Calculates trapezoid parameters so that the entry- and exit-speed is compensated by the provided factors.
  39 // The factors represent a factor of braking and must be in the range 0.0-1.0.
  40 //                                +--------+ <- nominal_rate
  41 //                               /          \
  42 // nominal_rate*entry_factor -> +            \
  43 //                              |             + <- nominal_rate*exit_factor
  44 //                              +-------------+
  45 //                                  time -->
  46 void Block::calculate_trapezoid( double entryfactor, double exitfactor ){
  47     this->initial_rate = ceil(this->nominal_rate * entryfactor);   // (step/min)
  48     this->final_rate   = ceil(this->nominal_rate * exitfactor);    // (step/min)
  49     double acceleration_per_minute = this->rate_delta * this->planner->kernel->stepper->acceleration_ticks_per_second * 60.0;
  50     int accelerate_steps = ceil( this->estimate_acceleration_distance( this->initial_rate, this->nominal_rate, acceleration_per_minute ) );
  51     int decelerate_steps = ceil( this->estimate_acceleration_distance( this->nominal_rate, this->final_rate,  -acceleration_per_minute ) );
  52
  53     // Calculate the size of Plateau of Nominal Rate.
  54     int plateau_steps = this->steps_event_count-accelerate_steps-decelerate_steps;
  55
  56    // Is the Plateau of Nominal Rate smaller than nothing? That means no cruising, and we will
  57    // have to use intersection_distance() to calculate when to abort acceleration and start braking
  58    // in order to reach the final_rate exactly at the end of this block.
  59    if (plateau_steps < 0) {
  60        accelerate_steps = ceil(this->intersection_distance(this->initial_rate, this->final_rate, acceleration_per_minute, this->steps_event_count));
  61        accelerate_steps = max( accelerate_steps, 0 ); // Check limits due to numerical round-off
  62        accelerate_steps = min( accelerate_steps, int(this->steps_event_count) );
  63        plateau_steps = 0;
  64    }
  65
  66    this->accelerate_until = accelerate_steps;
  67    this->decelerate_after = accelerate_steps+plateau_steps;
  68
  69 }
  70
  71 // Calculates the distance (not time) it takes to accelerate from initial_rate to target_rate using the
  72 // given acceleration:
  73 double Block::estimate_acceleration_distance(double initialrate, double targetrate, double acceleration) {
  74       return( (targetrate*targetrate-initialrate*initialrate)/(2L*acceleration));
  75 }
  76
  77 // This function gives you the point at which you must start braking (at the rate of -acceleration) if
  78 // you started at speed initial_rate and accelerated until this point and want to end at the final_rate after
  79 // a total travel of distance. This can be used to compute the intersection point between acceleration and
  80 // deceleration in the cases where the trapezoid has no plateau (i.e. never reaches maximum speed)
  81 //
  82 /*                          + <- some maximum rate we don't care about
  83                            /|\
  84                           / | \
  85                          /  |  + <- final_rate
  86                         /   |  |
  87        initial_rate -> +----+--+
  88                             ^ ^
  89                             | |
  90         intersection_distance distance */
  91 double Block::intersection_distance(double initialrate, double finalrate, double acceleration, double distance) {
  92    return((2*acceleration*distance-initialrate*initialrate+finalrate*finalrate)/(4*acceleration));
  93 }
  94
  95 // Calculates the maximum allowable speed at this point when you must be able to reach target_velocity using the
  96 // acceleration within the allotted distance.
  97 inline double max_allowable_speed(double acceleration, double target_velocity, double distance) {
  98   return(
  99     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
 100   );
 101 }
 102
 103
 104 // Called by Planner::recalculate() when scanning the plan from last to first entry.
 105 void Block::reverse_pass(Block* next, Block* previous){
 106
 107     if (next) {
 108         // If entry speed is already at the maximum entry speed, no need to recheck. Block is cruising.
 109         // If not, block in state of acceleration or deceleration. Reset entry speed to maximum and
 110         // check for maximum allowable speed reductions to ensure maximum possible planned speed.
 111         if (this->entry_speed != this->max_entry_speed) {
 112
 113             // If nominal length true, max junction speed is guaranteed to be reached. Only compute
 114             // for max allowable speed if block is decelerating and nominal length is false.
 115             if ((!this->nominal_length_flag) && (this->max_entry_speed > next->entry_speed)) {
 116                 this->entry_speed = min( this->max_entry_speed, max_allowable_speed(-this->planner->acceleration,next->entry_speed,this->millimeters));
 117             } else {
 118                 this->entry_speed = this->max_entry_speed;
 119             }
 120             this->recalculate_flag = true;
 121
 122         }
 123     } // Skip last block. Already initialized and set for recalculation.
 124
 125 }
 126
 127
 128 // Called by Planner::recalculate() when scanning the plan from first to last entry.
 129 void Block::forward_pass(Block* previous, Block* next){
 130
 131     if(!previous) { return; } // Begin planning after buffer_tail
 132
 133     // If the previous block is an acceleration block, but it is not long enough to complete the
 134     // full speed change within the block, we need to adjust the entry speed accordingly. Entry
 135     // speeds have already been reset, maximized, and reverse planned by reverse planner.
 136     // If nominal length is true, max junction speed is guaranteed to be reached. No need to recheck.
 137     if (!previous->nominal_length_flag) {
 138         if (previous->entry_speed < this->entry_speed) {
 139           double entry_speed = min( this->entry_speed,
 140             max_allowable_speed(-this->planner->acceleration,previous->entry_speed,previous->millimeters) );
 141
 142           // Check for junction speed change
 143           if (this->entry_speed != entry_speed) {
 144             this->entry_speed = entry_speed;
 145             this->recalculate_flag = true;
 146           }
 147         }
 148     }
 149
 150 }
 151
 152
 153 // Gcodes are attached to their respective blocks so that on_gcode_execute can be called with it
 154 void Block::append_gcode(Gcode* gcode){
 155    this->commands.push_back(gcode->command);
 156 }
 157
 158 // The attached gcodes are then poped and the on_gcode_execute event is called with them as a parameter
 159 void Block::pop_and_execute_gcode(Kernel* &kernel){
 160     for(unsigned short index=0; index<this->commands.size(); index++){
 161         string command = this->commands.at(index);
 162         Gcode gcode = Gcode();
 163         gcode.command = command;
 164         kernel->call_event(ON_GCODE_EXECUTE, &gcode );
 165     }
 166 }
 167
 168