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"
28 #define acceleration_checksum CHECKSUM("acceleration")
29 #define z_acceleration_checksum CHECKSUM("z_acceleration")
30 #define junction_deviation_checksum CHECKSUM("junction_deviation")
31 #define z_junction_deviation_checksum CHECKSUM("z_junction_deviation")
32 #define minimum_planner_speed_checksum CHECKSUM("minimum_planner_speed")
34 // The Planner does the acceleration math for the queue of Blocks ( movements ).
35 // It makes sure the speed stays within the configured constraints ( acceleration, junction_deviation, etc )
36 // It goes over the list in both direction, every time a block is added, re-doing the math to make sure everything is optimal
40 clear_vector_float(this->previous_unit_vec
);
44 // Configure acceleration
45 void Planner::config_load()
47 this->acceleration
= THEKERNEL
->config
->value(acceleration_checksum
)->by_default(100.0F
)->as_number(); // Acceleration is in mm/s^2
48 this->z_acceleration
= THEKERNEL
->config
->value(z_acceleration_checksum
)->by_default(0.0F
)->as_number(); // disabled by default
50 this->junction_deviation
= THEKERNEL
->config
->value(junction_deviation_checksum
)->by_default(0.05F
)->as_number();
51 this->z_junction_deviation
= THEKERNEL
->config
->value(z_junction_deviation_checksum
)->by_default(-1)->as_number(); // disabled by default
52 this->minimum_planner_speed
= THEKERNEL
->config
->value(minimum_planner_speed_checksum
)->by_default(0.0f
)->as_number();
56 // Append a block to the queue, compute it's speed factors
57 void Planner::append_block( ActuatorCoordinates
&actuator_pos
, float rate_mm_s
, float distance
, float unit_vec
[] )
59 float acceleration
, junction_deviation
;
61 // Create ( recycle ) a new block
62 Block
* block
= THEKERNEL
->conveyor
->queue
.head_ref();
66 for (size_t i
= 0; i
< THEKERNEL
->robot
->actuators
.size(); i
++) {
67 int steps
= THEKERNEL
->robot
->actuators
[i
]->steps_to_target(actuator_pos
[i
]);
69 block
->direction_bits
[i
] = (steps
< 0) ? 1 : 0;
71 // Update current position
72 THEKERNEL
->robot
->actuators
[i
]->last_milestone_steps
+= steps
;
73 THEKERNEL
->robot
->actuators
[i
]->last_milestone_mm
= actuator_pos
[i
];
75 block
->steps
[i
] = labs(steps
);
78 acceleration
= this->acceleration
;
79 junction_deviation
= this->junction_deviation
;
81 // use either regular acceleration or a z only move accleration
82 if(block
->steps
[ALPHA_STEPPER
] == 0 && block
->steps
[BETA_STEPPER
] == 0) {
84 if(this->z_acceleration
> 0.0F
) acceleration
= this->z_acceleration
;
85 if(this->z_junction_deviation
>= 0.0F
) junction_deviation
= this->z_junction_deviation
;
88 block
->acceleration
= acceleration
; // save in block
90 // Max number of steps, for all axes
91 uint32_t steps_event_count
= 0;
92 for (size_t s
= 0; s
< THEKERNEL
->robot
->actuators
.size(); s
++) {
93 steps_event_count
= std::max(steps_event_count
, block
->steps
[s
]);
95 block
->steps_event_count
= steps_event_count
;
97 block
->millimeters
= distance
;
99 // Calculate speed in mm/sec for each axis. No divide by zero due to previous checks.
100 // NOTE: Minimum stepper speed is limited by MINIMUM_STEPS_PER_MINUTE in stepper.c
101 if( distance
> 0.0F
) {
102 block
->nominal_speed
= rate_mm_s
; // (mm/s) Always > 0
103 block
->nominal_rate
= block
->steps_event_count
* rate_mm_s
/ distance
; // (step/s) Always > 0
105 block
->nominal_speed
= 0.0F
;
106 block
->nominal_rate
= 0;
109 // Compute the acceleration rate for the trapezoid generator. Depending on the slope of the line
110 // average travel per step event changes. For a line along one axis the travel per step event
111 // is equal to the travel/step in the particular axis. For a 45 degree line the steppers of both
112 // axes might step for every step event. Travel per step event is then sqrt(travel_x^2+travel_y^2).
114 // Compute maximum allowable entry speed at junction by centripetal acceleration approximation.
115 // Let a circle be tangent to both previous and current path line segments, where the junction
116 // deviation is defined as the distance from the junction to the closest edge of the circle,
117 // colinear with the circle center. The circular segment joining the two paths represents the
118 // path of centripetal acceleration. Solve for max velocity based on max acceleration about the
119 // radius of the circle, defined indirectly by junction deviation. This may be also viewed as
120 // path width or max_jerk in the previous grbl version. This approach does not actually deviate
121 // from path, but used as a robust way to compute cornering speeds, as it takes into account the
122 // nonlinearities of both the junction angle and junction velocity.
124 // NOTE however it does not take into account independent axis, in most cartesian X and Y and Z are totally independent
125 // 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.
126 float vmax_junction
= minimum_planner_speed
; // Set default max junction speed
128 if (!THEKERNEL
->conveyor
->is_queue_empty()) {
129 float previous_nominal_speed
= THEKERNEL
->conveyor
->queue
.item_ref(THEKERNEL
->conveyor
->queue
.prev(THEKERNEL
->conveyor
->queue
.head_i
))->nominal_speed
;
131 if (previous_nominal_speed
> 0.0F
&& junction_deviation
> 0.0F
) {
132 // Compute cosine of angle between previous and current path. (prev_unit_vec is negative)
133 // NOTE: Max junction velocity is computed without sin() or acos() by trig half angle identity.
134 float cos_theta
= - this->previous_unit_vec
[X_AXIS
] * unit_vec
[X_AXIS
]
135 - this->previous_unit_vec
[Y_AXIS
] * unit_vec
[Y_AXIS
]
136 - this->previous_unit_vec
[Z_AXIS
] * unit_vec
[Z_AXIS
] ;
138 // Skip and use default max junction speed for 0 degree acute junction.
139 if (cos_theta
< 0.95F
) {
140 vmax_junction
= min(previous_nominal_speed
, block
->nominal_speed
);
141 // Skip and avoid divide by zero for straight junctions at 180 degrees. Limit to min() of nominal speeds.
142 if (cos_theta
> -0.95F
) {
143 // Compute maximum junction velocity based on maximum acceleration and junction deviation
144 float sin_theta_d2
= sqrtf(0.5F
* (1.0F
- cos_theta
)); // Trig half angle identity. Always positive.
145 vmax_junction
= min(vmax_junction
, sqrtf(acceleration
* junction_deviation
* sin_theta_d2
/ (1.0F
- sin_theta_d2
)));
150 block
->max_entry_speed
= vmax_junction
;
152 // Initialize block entry speed. Compute based on deceleration to user-defined minimum_planner_speed.
153 float v_allowable
= max_allowable_speed(-acceleration
, minimum_planner_speed
, block
->millimeters
);
154 block
->entry_speed
= min(vmax_junction
, v_allowable
);
156 // Initialize planner efficiency flags
157 // Set flag if block will always reach maximum junction speed regardless of entry/exit speeds.
158 // If a block can de/ac-celerate from nominal speed to zero within the length of the block, then
159 // the current block and next block junction speeds are guaranteed to always be at their maximum
160 // junction speeds in deceleration and acceleration, respectively. This is due to how the current
161 // block nominal speed limits both the current and next maximum junction speeds. Hence, in both
162 // the reverse and forward planners, the corresponding block junction speed will always be at the
163 // the maximum junction speed and may always be ignored for any speed reduction checks.
164 if (block
->nominal_speed
<= v_allowable
) { block
->nominal_length_flag
= true; }
165 else { block
->nominal_length_flag
= false; }
167 // Always calculate trapezoid for new block
168 block
->recalculate_flag
= true;
170 // Update previous path unit_vector and nominal speed
171 memcpy(this->previous_unit_vec
, unit_vec
, sizeof(previous_unit_vec
)); // previous_unit_vec[] = unit_vec[]
173 // Math-heavy re-computing of the whole queue to take the new
176 // The block can now be used
179 THEKERNEL
->conveyor
->queue_head_block();
182 void Planner::recalculate()
184 Conveyor::Queue_t
&queue
= THEKERNEL
->conveyor
->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
));