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/>.
12 #include "nuts_bolts.h"
13 #include "RingBuffer.h"
20 #include "StepperMotor.h"
22 #include "checksumm.h"
24 #include "ConfigValue.h"
29 #define junction_deviation_checksum CHECKSUM("junction_deviation")
30 #define z_junction_deviation_checksum CHECKSUM("z_junction_deviation")
31 #define minimum_planner_speed_checksum CHECKSUM("minimum_planner_speed")
33 // The Planner does the acceleration math for the queue of Blocks ( movements ).
34 // It makes sure the speed stays within the configured constraints ( acceleration, junction_deviation, etc )
35 // It goes over the list in both direction, every time a block is added, re-doing the math to make sure everything is optimal
39 memset(this->previous_unit_vec
, 0, sizeof this->previous_unit_vec
);
43 // Configure acceleration
44 void Planner::config_load()
46 this->junction_deviation
= THEKERNEL
->config
->value(junction_deviation_checksum
)->by_default(0.05F
)->as_number();
47 this->z_junction_deviation
= THEKERNEL
->config
->value(z_junction_deviation_checksum
)->by_default(NAN
)->as_number(); // disabled by default
48 this->minimum_planner_speed
= THEKERNEL
->config
->value(minimum_planner_speed_checksum
)->by_default(0.0f
)->as_number();
52 // Append a block to the queue, compute it's speed factors
53 void Planner::append_block( ActuatorCoordinates
&actuator_pos
, uint8_t n_motors
, float rate_mm_s
, float distance
, float *unit_vec
, float acceleration
)
55 // Create ( recycle ) a new block
56 Block
* block
= THECONVEYOR
->queue
.head_ref();
59 for (size_t i
= 0; i
< n_motors
; i
++) {
60 int32_t steps
= THEROBOT
->actuators
[i
]->steps_to_target(actuator_pos
[i
]);
61 // Update current position
62 THEROBOT
->actuators
[i
]->update_last_milestones(actuator_pos
[i
], steps
);
65 block
->direction_bits
[i
] = (steps
< 0) ? 1 : 0;
67 // save actual steps in block
68 block
->steps
[i
] = labs(steps
);
72 float junction_deviation
= this->junction_deviation
;
74 // use either regular junction deviation or z specific and see if a primary axis move
75 block
->primary_axis
= true;
76 if(block
->steps
[ALPHA_STEPPER
] == 0 && block
->steps
[BETA_STEPPER
] == 0){
77 if(block
->steps
[GAMMA_STEPPER
] != 0) {
79 if(!isnan(this->z_junction_deviation
)) junction_deviation
= this->z_junction_deviation
;
81 // is not a primary axis move
82 block
->primary_axis
= false;
86 block
->acceleration
= acceleration
; // save in block
88 // Max number of steps, for all axes
89 auto mi
= std::max_element(block
->steps
.begin(), block
->steps
.end());
90 block
->steps_event_count
= *mi
;
92 block
->millimeters
= distance
;
94 // Calculate speed in mm/sec for each axis. No divide by zero due to previous checks.
95 if( distance
> 0.0F
) {
96 block
->nominal_speed
= rate_mm_s
; // (mm/s) Always > 0
97 block
->nominal_rate
= block
->steps_event_count
* rate_mm_s
/ distance
; // (step/s) Always > 0
99 block
->nominal_speed
= 0.0F
;
100 block
->nominal_rate
= 0;
103 // Compute the acceleration rate for the trapezoid generator. Depending on the slope of the line
104 // average travel per step event changes. For a line along one axis the travel per step event
105 // is equal to the travel/step in the particular axis. For a 45 degree line the steppers of both
106 // axes might step for every step event. Travel per step event is then sqrt(travel_x^2+travel_y^2).
108 // Compute maximum allowable entry speed at junction by centripetal acceleration approximation.
109 // Let a circle be tangent to both previous and current path line segments, where the junction
110 // deviation is defined as the distance from the junction to the closest edge of the circle,
111 // colinear with the circle center. The circular segment joining the two paths represents the
112 // path of centripetal acceleration. Solve for max velocity based on max acceleration about the
113 // radius of the circle, defined indirectly by junction deviation. This may be also viewed as
114 // path width or max_jerk in the previous grbl version. This approach does not actually deviate
115 // from path, but used as a robust way to compute cornering speeds, as it takes into account the
116 // nonlinearities of both the junction angle and junction velocity.
118 // NOTE however it does not take into account independent axis, in most cartesian X and Y and Z are totally independent
119 // and this allows one to stop with little to no decleration in many cases. This is particualrly bad on leadscrew based systems that will skip steps.
120 float vmax_junction
= minimum_planner_speed
; // Set default max junction speed
122 // if unit_vec was null then it was not a primary axis move so we skip the junction deviation stuff
123 if (unit_vec
!= nullptr && !THECONVEYOR
->is_queue_empty()) {
124 Block
*prev_block
= THECONVEYOR
->queue
.item_ref(THECONVEYOR
->queue
.prev(THECONVEYOR
->queue
.head_i
));
125 float previous_nominal_speed
= prev_block
->primary_axis
? prev_block
->nominal_speed
: 0;
127 if (junction_deviation
> 0.0F
&& previous_nominal_speed
> 0.0F
) {
128 // Compute cosine of angle between previous and current path. (prev_unit_vec is negative)
129 // NOTE: Max junction velocity is computed without sin() or acos() by trig half angle identity.
130 float cos_theta
= - this->previous_unit_vec
[X_AXIS
] * unit_vec
[X_AXIS
]
131 - this->previous_unit_vec
[Y_AXIS
] * unit_vec
[Y_AXIS
]
132 - this->previous_unit_vec
[Z_AXIS
] * unit_vec
[Z_AXIS
] ;
134 // Skip and use default max junction speed for 0 degree acute junction.
135 if (cos_theta
< 0.95F
) {
136 vmax_junction
= std::min(previous_nominal_speed
, block
->nominal_speed
);
137 // Skip and avoid divide by zero for straight junctions at 180 degrees. Limit to min() of nominal speeds.
138 if (cos_theta
> -0.95F
) {
139 // Compute maximum junction velocity based on maximum acceleration and junction deviation
140 float sin_theta_d2
= sqrtf(0.5F
* (1.0F
- cos_theta
)); // Trig half angle identity. Always positive.
141 vmax_junction
= std::min(vmax_junction
, sqrtf(acceleration
* junction_deviation
* sin_theta_d2
/ (1.0F
- sin_theta_d2
)));
146 block
->max_entry_speed
= vmax_junction
;
148 // Initialize block entry speed. Compute based on deceleration to user-defined minimum_planner_speed.
149 float v_allowable
= max_allowable_speed(-acceleration
, minimum_planner_speed
, block
->millimeters
);
150 block
->entry_speed
= std::min(vmax_junction
, v_allowable
);
152 // Initialize planner efficiency flags
153 // Set flag if block will always reach maximum junction speed regardless of entry/exit speeds.
154 // If a block can de/ac-celerate from nominal speed to zero within the length of the block, then
155 // the current block and next block junction speeds are guaranteed to always be at their maximum
156 // junction speeds in deceleration and acceleration, respectively. This is due to how the current
157 // block nominal speed limits both the current and next maximum junction speeds. Hence, in both
158 // the reverse and forward planners, the corresponding block junction speed will always be at the
159 // the maximum junction speed and may always be ignored for any speed reduction checks.
160 if (block
->nominal_speed
<= v_allowable
) { block
->nominal_length_flag
= true; }
161 else { block
->nominal_length_flag
= false; }
163 // Always calculate trapezoid for new block
164 block
->recalculate_flag
= true;
166 // Update previous path unit_vector and nominal speed
167 if(unit_vec
!= nullptr) {
168 memcpy(previous_unit_vec
, unit_vec
, sizeof(previous_unit_vec
)); // previous_unit_vec[] = unit_vec[]
170 memset(previous_unit_vec
, 0, sizeof(previous_unit_vec
));
173 // Math-heavy re-computing of the whole queue to take the new
176 // The block can now be used
179 THECONVEYOR
->queue_head_block();
182 void Planner::recalculate()
184 Conveyor::Queue_t
&queue
= THECONVEYOR
->queue
;
186 unsigned int block_index
;
192 * a newly added block is decel limited
194 * we find its max entry speed given its exit speed
196 * for each block, walking backwards in the queue:
198 * if max entry speed == current entry speed
199 * then we can set recalculate to false, since clearly adding another block didn't allow us to enter faster
200 * and thus we don't need to check entry speed for this block any more
202 * once we find an accel limited block, we must find the max exit speed and walk the queue forwards
204 * for each block, walking forwards in the queue:
206 * given the exit speed of the previous block and our own max entry speed
207 * we can tell if we're accel or decel limited (or coasting)
209 * if prev_exit > max_entry
210 * then we're still decel limited. update previous trapezoid with our max entry for prev exit
211 * if max_entry >= prev_exit
212 * then we're accel limited. set recalculate to false, work out max exit speed
214 * finally, work out trapezoid for the final (and newest) block.
219 * For each block, given the exit speed and acceleration, find the maximum entry speed
222 float entry_speed
= minimum_planner_speed
;
224 block_index
= queue
.head_i
;
225 current
= queue
.item_ref(block_index
);
227 if (!queue
.is_empty()) {
228 while ((block_index
!= queue
.tail_i
) && current
->recalculate_flag
) {
229 entry_speed
= current
->reverse_pass(entry_speed
);
231 block_index
= queue
.prev(block_index
);
232 current
= queue
.item_ref(block_index
);
237 * now current points to either tail or first non-recalculate block
238 * and has not had its reverse_pass called
239 * or its calculate_trapezoid
240 * entry_speed is set to the *exit* speed of current.
241 * each block from current to head has its entry speed set to its max entry speed- limited by decel or nominal_rate
244 float exit_speed
= current
->max_exit_speed();
246 while (block_index
!= queue
.head_i
) {
248 block_index
= queue
.next(block_index
);
249 current
= queue
.item_ref(block_index
);
251 // we pass the exit speed of the previous block
252 // so this block can decide if it's accel or decel limited and update its fields as appropriate
253 exit_speed
= current
->forward_pass(exit_speed
);
255 previous
->calculate_trapezoid(previous
->entry_speed
, current
->entry_speed
);
261 * work out trapezoid for final (and newest) block
264 // now current points to the head item
265 // which has not had calculate_trapezoid run yet
266 current
->calculate_trapezoid(current
->entry_speed
, minimum_planner_speed
);
270 // Calculates the maximum allowable speed at this point when you must be able to reach target_velocity using the
271 // acceleration within the allotted distance.
272 float Planner::max_allowable_speed(float acceleration
, float target_velocity
, float distance
)
274 // Was acceleration*60*60*distance, in case this breaks, but here we prefer to use seconds instead of minutes
275 return(sqrtf(target_velocity
* target_velocity
- 2.0F
* acceleration
* distance
));