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 bool Planner::append_block( ActuatorCoordinates
&actuator_pos
, uint8_t n_motors
, float rate_mm_s
, float distance
, float *unit_vec
, float acceleration
, float s_value
, bool g123
)
55 // Create ( recycle ) a new block
56 Block
* block
= THECONVEYOR
->queue
.head_ref();
59 bool has_steps
= false;
60 for (size_t i
= 0; i
< n_motors
; i
++) {
61 int32_t steps
= THEROBOT
->actuators
[i
]->steps_to_target(actuator_pos
[i
]);
62 // Update current position
64 THEROBOT
->actuators
[i
]->update_last_milestones(actuator_pos
[i
], steps
);
69 block
->direction_bits
[i
] = (steps
< 0) ? 1 : 0;
70 // save actual steps in block
71 block
->steps
[i
] = labs(steps
);
74 // sometimes even though there is a detectable movement it turns out there are no steps to be had from such a small move
80 // info needed by laser
81 block
->s_value
= roundf(s_value
*(1<<11)); // 1.11 fixed point
82 block
->is_g123
= g123
;
85 float junction_deviation
= this->junction_deviation
;
87 // use either regular junction deviation or z specific and see if a primary axis move
88 block
->primary_axis
= true;
89 if(block
->steps
[ALPHA_STEPPER
] == 0 && block
->steps
[BETA_STEPPER
] == 0) {
90 if(block
->steps
[GAMMA_STEPPER
] != 0) {
92 if(!isnan(this->z_junction_deviation
)) junction_deviation
= this->z_junction_deviation
;
95 // is not a primary axis move
96 block
->primary_axis
= false;
97 #if N_PRIMARY_AXIS > 3
98 for (int i
= 3; i
< N_PRIMARY_AXIS
; ++i
) {
99 if(block
->steps
[i
] != 0){
100 block
->primary_axis
= true;
109 block
->acceleration
= acceleration
; // save in block
111 // Max number of steps, for all axes
112 auto mi
= std::max_element(block
->steps
.begin(), block
->steps
.end());
113 block
->steps_event_count
= *mi
;
115 block
->millimeters
= distance
;
117 // Calculate speed in mm/sec for each axis. No divide by zero due to previous checks.
118 if( distance
> 0.0F
) {
119 block
->nominal_speed
= rate_mm_s
; // (mm/s) Always > 0
120 block
->nominal_rate
= block
->steps_event_count
* rate_mm_s
/ distance
; // (step/s) Always > 0
122 block
->nominal_speed
= 0.0F
;
123 block
->nominal_rate
= 0;
126 // Compute the acceleration rate for the trapezoid generator. Depending on the slope of the line
127 // average travel per step event changes. For a line along one axis the travel per step event
128 // is equal to the travel/step in the particular axis. For a 45 degree line the steppers of both
129 // axes might step for every step event. Travel per step event is then sqrt(travel_x^2+travel_y^2).
131 // Compute maximum allowable entry speed at junction by centripetal acceleration approximation.
132 // Let a circle be tangent to both previous and current path line segments, where the junction
133 // deviation is defined as the distance from the junction to the closest edge of the circle,
134 // colinear with the circle center. The circular segment joining the two paths represents the
135 // path of centripetal acceleration. Solve for max velocity based on max acceleration about the
136 // radius of the circle, defined indirectly by junction deviation. This may be also viewed as
137 // path width or max_jerk in the previous grbl version. This approach does not actually deviate
138 // from path, but used as a robust way to compute cornering speeds, as it takes into account the
139 // nonlinearities of both the junction angle and junction velocity.
141 // NOTE however it does not take into account independent axis, in most cartesian X and Y and Z are totally independent
142 // 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.
143 float vmax_junction
= minimum_planner_speed
; // Set default max junction speed
145 // if unit_vec was null then it was not a primary axis move so we skip the junction deviation stuff
146 if (unit_vec
!= nullptr && !THECONVEYOR
->is_queue_empty()) {
147 Block
*prev_block
= THECONVEYOR
->queue
.item_ref(THECONVEYOR
->queue
.prev(THECONVEYOR
->queue
.head_i
));
148 float previous_nominal_speed
= prev_block
->primary_axis
? prev_block
->nominal_speed
: 0;
150 if (junction_deviation
> 0.0F
&& previous_nominal_speed
> 0.0F
) {
151 // Compute cosine of angle between previous and current path. (prev_unit_vec is negative)
152 // NOTE: Max junction velocity is computed without sin() or acos() by trig half angle identity.
153 float cos_theta
= - this->previous_unit_vec
[X_AXIS
] * unit_vec
[X_AXIS
]
154 - this->previous_unit_vec
[Y_AXIS
] * unit_vec
[Y_AXIS
]
155 - this->previous_unit_vec
[Z_AXIS
] * unit_vec
[Z_AXIS
];
156 #if N_PRIMARY_AXIS > 3
157 for (int i
= 3; i
< N_PRIMARY_AXIS
; ++i
) {
158 cos_theta
-= this->previous_unit_vec
[i
] * unit_vec
[i
];
162 // Skip and use default max junction speed for 0 degree acute junction.
163 if (cos_theta
< 0.999999F
) {
164 vmax_junction
= std::min(previous_nominal_speed
, block
->nominal_speed
);
165 // Skip and avoid divide by zero for straight junctions at 180 degrees. Limit to min() of nominal speeds.
166 if (cos_theta
> -0.999999F
) {
167 // Compute maximum junction velocity based on maximum acceleration and junction deviation
168 float sin_theta_d2
= sqrtf(0.5F
* (1.0F
- cos_theta
)); // Trig half angle identity. Always positive.
169 vmax_junction
= std::min(vmax_junction
, sqrtf(acceleration
* junction_deviation
* sin_theta_d2
/ (1.0F
- sin_theta_d2
)));
174 block
->max_entry_speed
= vmax_junction
;
176 // Initialize block entry speed. Compute based on deceleration to user-defined minimum_planner_speed.
177 float v_allowable
= max_allowable_speed(-acceleration
, minimum_planner_speed
, block
->millimeters
);
178 block
->entry_speed
= std::min(vmax_junction
, v_allowable
);
180 // Initialize planner efficiency flags
181 // Set flag if block will always reach maximum junction speed regardless of entry/exit speeds.
182 // If a block can de/ac-celerate from nominal speed to zero within the length of the block, then
183 // the current block and next block junction speeds are guaranteed to always be at their maximum
184 // junction speeds in deceleration and acceleration, respectively. This is due to how the current
185 // block nominal speed limits both the current and next maximum junction speeds. Hence, in both
186 // the reverse and forward planners, the corresponding block junction speed will always be at the
187 // the maximum junction speed and may always be ignored for any speed reduction checks.
188 if (block
->nominal_speed
<= v_allowable
) { block
->nominal_length_flag
= true; }
189 else { block
->nominal_length_flag
= false; }
191 // Always calculate trapezoid for new block
192 block
->recalculate_flag
= true;
194 // Update previous path unit_vector and nominal speed
195 if(unit_vec
!= nullptr) {
196 memcpy(previous_unit_vec
, unit_vec
, sizeof(previous_unit_vec
)); // previous_unit_vec[] = unit_vec[]
198 memset(previous_unit_vec
, 0, sizeof(previous_unit_vec
));
201 // Math-heavy re-computing of the whole queue to take the new
204 // The block can now be used
207 THECONVEYOR
->queue_head_block();
212 void Planner::recalculate()
214 Conveyor::Queue_t
&queue
= THECONVEYOR
->queue
;
216 unsigned int block_index
;
222 * a newly added block is decel limited
224 * we find its max entry speed given its exit speed
226 * for each block, walking backwards in the queue:
228 * if max entry speed == current entry speed
229 * then we can set recalculate to false, since clearly adding another block didn't allow us to enter faster
230 * and thus we don't need to check entry speed for this block any more
232 * once we find an accel limited block, we must find the max exit speed and walk the queue forwards
234 * for each block, walking forwards in the queue:
236 * given the exit speed of the previous block and our own max entry speed
237 * we can tell if we're accel or decel limited (or coasting)
239 * if prev_exit > max_entry
240 * then we're still decel limited. update previous trapezoid with our max entry for prev exit
241 * if max_entry >= prev_exit
242 * then we're accel limited. set recalculate to false, work out max exit speed
244 * finally, work out trapezoid for the final (and newest) block.
249 * For each block, given the exit speed and acceleration, find the maximum entry speed
252 float entry_speed
= minimum_planner_speed
;
254 block_index
= queue
.head_i
;
255 current
= queue
.item_ref(block_index
);
257 if (!queue
.is_empty()) {
258 while ((block_index
!= queue
.tail_i
) && current
->recalculate_flag
) {
259 entry_speed
= current
->reverse_pass(entry_speed
);
261 block_index
= queue
.prev(block_index
);
262 current
= queue
.item_ref(block_index
);
267 * now current points to either tail or first non-recalculate block
268 * and has not had its reverse_pass called
269 * or its calculate_trapezoid
270 * entry_speed is set to the *exit* speed of current.
271 * each block from current to head has its entry speed set to its max entry speed- limited by decel or nominal_rate
274 float exit_speed
= current
->max_exit_speed();
276 while (block_index
!= queue
.head_i
) {
278 block_index
= queue
.next(block_index
);
279 current
= queue
.item_ref(block_index
);
281 // we pass the exit speed of the previous block
282 // so this block can decide if it's accel or decel limited and update its fields as appropriate
283 exit_speed
= current
->forward_pass(exit_speed
);
285 previous
->calculate_trapezoid(previous
->entry_speed
, current
->entry_speed
);
291 * work out trapezoid for final (and newest) block
294 // now current points to the head item
295 // which has not had calculate_trapezoid run yet
296 current
->calculate_trapezoid(current
->entry_speed
, minimum_planner_speed
);
300 // Calculates the maximum allowable speed at this point when you must be able to reach target_velocity using the
301 // acceleration within the allotted distance.
302 float Planner::max_allowable_speed(float acceleration
, float target_velocity
, float distance
)
304 // Was acceleration*60*60*distance, in case this breaks, but here we prefer to use seconds instead of minutes
305 return(sqrtf(target_velocity
* target_velocity
- 2.0F
* acceleration
* distance
));