Adapt speed/jerk code based on Prusa MK2 branch
This commit is contained in:
Scott Lahteine
parent
8e1cc9332a
commit
1092319b19
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@ -85,8 +85,8 @@ float Planner::max_feedrate_mm_s[NUM_AXIS], // Max speeds in mm per second
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Planner::axis_steps_per_mm[NUM_AXIS],
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Planner::steps_to_mm[NUM_AXIS];
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unsigned long Planner::max_acceleration_steps_per_s2[NUM_AXIS],
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Planner::max_acceleration_mm_per_s2[NUM_AXIS]; // Use M201 to override by software
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uint32_t Planner::max_acceleration_steps_per_s2[NUM_AXIS],
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Planner::max_acceleration_mm_per_s2[NUM_AXIS]; // Use M201 to override by software
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millis_t Planner::min_segment_time;
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float Planner::min_feedrate_mm_s,
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@ -236,6 +236,7 @@ void Planner::reverse_pass() {
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uint8_t b = BLOCK_MOD(block_buffer_head - 3);
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while (b != tail) {
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if (block[0] && (block[0]->flag & BLOCK_FLAG_START_FROM_FULL_HALT)) break;
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b = prev_block_index(b);
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block[2] = block[1];
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block[1] = block[0];
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@ -696,6 +697,9 @@ void Planner::_buffer_line(const float &a, const float &b, const float &c, const
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// Bail if this is a zero-length block
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if (block->step_event_count < MIN_STEPS_PER_SEGMENT) return;
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// Clear the block flags
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block->flag = 0;
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// For a mixing extruder, get a magnified step_event_count for each
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#if ENABLED(MIXING_EXTRUDER)
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for (uint8_t i = 0; i < MIXING_STEPPERS; i++)
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@ -1011,90 +1015,170 @@ void Planner::_buffer_line(const float &a, const float &b, const float &c, const
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// Compute and limit the acceleration rate for the trapezoid generator.
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float steps_per_mm = block->step_event_count / block->millimeters;
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uint32_t accel;
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if (!block->steps[X_AXIS] && !block->steps[Y_AXIS] && !block->steps[Z_AXIS]) {
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block->acceleration_steps_per_s2 = ceil(retract_acceleration * steps_per_mm); // convert to: acceleration steps/sec^2
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// convert to: acceleration steps/sec^2
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accel = ceil(retract_acceleration * steps_per_mm);
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}
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else {
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#define LIMIT_ACCEL(AXIS) do{ \
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const uint32_t comp = max_acceleration_steps_per_s2[AXIS] * block->step_event_count; \
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if (accel * block->steps[AXIS] > comp) accel = comp / block->steps[AXIS]; \
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}while(0)
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// Start with print or travel acceleration
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accel = ceil((block->steps[E_AXIS] ? acceleration : travel_acceleration) * steps_per_mm);
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// Limit acceleration per axis
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block->acceleration_steps_per_s2 = ceil((block->steps[E_AXIS] ? acceleration : travel_acceleration) * steps_per_mm);
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if (max_acceleration_steps_per_s2[X_AXIS] < (block->acceleration_steps_per_s2 * block->steps[X_AXIS]) / block->step_event_count)
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block->acceleration_steps_per_s2 = (max_acceleration_steps_per_s2[X_AXIS] * block->step_event_count) / block->steps[X_AXIS];
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if (max_acceleration_steps_per_s2[Y_AXIS] < (block->acceleration_steps_per_s2 * block->steps[Y_AXIS]) / block->step_event_count)
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block->acceleration_steps_per_s2 = (max_acceleration_steps_per_s2[Y_AXIS] * block->step_event_count) / block->steps[Y_AXIS];
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if (max_acceleration_steps_per_s2[Z_AXIS] < (block->acceleration_steps_per_s2 * block->steps[Z_AXIS]) / block->step_event_count)
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block->acceleration_steps_per_s2 = (max_acceleration_steps_per_s2[Z_AXIS] * block->step_event_count) / block->steps[Z_AXIS];
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if (max_acceleration_steps_per_s2[E_AXIS] < (block->acceleration_steps_per_s2 * block->steps[E_AXIS]) / block->step_event_count)
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block->acceleration_steps_per_s2 = (max_acceleration_steps_per_s2[E_AXIS] * block->step_event_count) / block->steps[E_AXIS];
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LIMIT_ACCEL(X_AXIS);
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LIMIT_ACCEL(Y_AXIS);
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LIMIT_ACCEL(Z_AXIS);
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LIMIT_ACCEL(E_AXIS);
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}
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block->acceleration = block->acceleration_steps_per_s2 / steps_per_mm;
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block->acceleration_rate = (long)(block->acceleration_steps_per_s2 * 16777216.0 / ((F_CPU) * 0.125));
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block->acceleration_steps_per_s2 = accel;
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block->acceleration = accel / steps_per_mm;
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block->acceleration_rate = (long)(accel * 16777216.0 / ((F_CPU) * 0.125)); // * 8.388608
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// Initial limit on the segment entry velocity
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float vmax_junction;
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#if 0 // Use old jerk for now
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float junction_deviation = 0.1;
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// Compute path unit vector
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double unit_vec[XYZ];
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double unit_vec[XYZ] = {
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delta_mm[X_AXIS] * inverse_millimeters,
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delta_mm[Y_AXIS] * inverse_millimeters,
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delta_mm[Z_AXIS] * inverse_millimeters
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};
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unit_vec[X_AXIS] = delta_mm[X_AXIS] * inverse_millimeters;
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unit_vec[Y_AXIS] = delta_mm[Y_AXIS] * inverse_millimeters;
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unit_vec[Z_AXIS] = delta_mm[Z_AXIS] * inverse_millimeters;
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/*
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Compute maximum allowable entry speed at junction by centripetal acceleration approximation.
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// Compute maximum allowable entry speed at junction by centripetal acceleration approximation.
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// Let a circle be tangent to both previous and current path line segments, where the junction
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// deviation is defined as the distance from the junction to the closest edge of the circle,
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// collinear with the circle center. The circular segment joining the two paths represents the
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// path of centripetal acceleration. Solve for max velocity based on max acceleration about the
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// radius of the circle, defined indirectly by junction deviation. This may be also viewed as
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// path width or max_jerk in the previous grbl version. This approach does not actually deviate
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// from path, but used as a robust way to compute cornering speeds, as it takes into account the
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// nonlinearities of both the junction angle and junction velocity.
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double vmax_junction = MINIMUM_PLANNER_SPEED; // Set default max junction speed
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Let a circle be tangent to both previous and current path line segments, where the junction
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deviation is defined as the distance from the junction to the closest edge of the circle,
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collinear with the circle center.
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The circular segment joining the two paths represents the path of centripetal acceleration.
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Solve for max velocity based on max acceleration about the radius of the circle, defined
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indirectly by junction deviation.
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This may be also viewed as path width or max_jerk in the previous grbl version. This approach
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does not actually deviate from path, but used as a robust way to compute cornering speeds, as
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it takes into account the nonlinearities of both the junction angle and junction velocity.
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*/
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vmax_junction = MINIMUM_PLANNER_SPEED; // Set default max junction speed
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// Skip first block or when previous_nominal_speed is used as a flag for homing and offset cycles.
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if ((block_buffer_head != block_buffer_tail) && (previous_nominal_speed > 0.0)) {
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if (block_buffer_head != block_buffer_tail && previous_nominal_speed > 0.0) {
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// Compute cosine of angle between previous and current path. (prev_unit_vec is negative)
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// NOTE: Max junction velocity is computed without sin() or acos() by trig half angle identity.
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double cos_theta = - previous_unit_vec[X_AXIS] * unit_vec[X_AXIS]
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- previous_unit_vec[Y_AXIS] * unit_vec[Y_AXIS]
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- previous_unit_vec[Z_AXIS] * unit_vec[Z_AXIS] ;
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float cos_theta = - previous_unit_vec[X_AXIS] * unit_vec[X_AXIS]
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- previous_unit_vec[Y_AXIS] * unit_vec[Y_AXIS]
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- previous_unit_vec[Z_AXIS] * unit_vec[Z_AXIS] ;
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// Skip and use default max junction speed for 0 degree acute junction.
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if (cos_theta < 0.95) {
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vmax_junction = min(previous_nominal_speed, block->nominal_speed);
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// Skip and avoid divide by zero for straight junctions at 180 degrees. Limit to min() of nominal speeds.
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if (cos_theta > -0.95) {
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// Compute maximum junction velocity based on maximum acceleration and junction deviation
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double sin_theta_d2 = sqrt(0.5 * (1.0 - cos_theta)); // Trig half angle identity. Always positive.
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float sin_theta_d2 = sqrt(0.5 * (1.0 - cos_theta)); // Trig half angle identity. Always positive.
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NOMORE(vmax_junction, sqrt(block->acceleration * junction_deviation * sin_theta_d2 / (1.0 - sin_theta_d2)));
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}
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}
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}
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#endif
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// Start with a safe speed
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float vmax_junction = max_jerk[X_AXIS] * 0.5, vmax_junction_factor = 1.0;
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if (max_jerk[Y_AXIS] * 0.5 < fabs(current_speed[Y_AXIS])) NOMORE(vmax_junction, max_jerk[Y_AXIS] * 0.5);
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if (max_jerk[Z_AXIS] * 0.5 < fabs(current_speed[Z_AXIS])) NOMORE(vmax_junction, max_jerk[Z_AXIS] * 0.5);
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if (max_jerk[E_AXIS] * 0.5 < fabs(current_speed[E_AXIS])) NOMORE(vmax_junction, max_jerk[E_AXIS] * 0.5);
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NOMORE(vmax_junction, block->nominal_speed);
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float safe_speed = vmax_junction;
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/**
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* Adapted from Prusa MKS firmware
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*
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* Start with a safe speed (from which the machine may halt to stop immediately).
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*/
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// Exit speed limited by a jerk to full halt of a previous last segment
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static float previous_safe_speed;
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float safe_speed = block->nominal_speed;
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bool limited = false;
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LOOP_XYZE(i) {
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float jerk = fabs(current_speed[i]);
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if (jerk > max_jerk[i]) {
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// The actual jerk is lower if it has been limited by the XY jerk.
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if (limited) {
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// Spare one division by a following gymnastics:
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// Instead of jerk *= safe_speed / block->nominal_speed,
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// multiply max_jerk[i] by the divisor.
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jerk *= safe_speed;
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float mjerk = max_jerk[i] * block->nominal_speed;
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if (jerk > mjerk) safe_speed *= mjerk / jerk;
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}
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else {
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safe_speed = max_jerk[i];
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limited = true;
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}
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}
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}
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if (moves_queued > 1 && previous_nominal_speed > 0.0001) {
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//if ((fabs(previous_speed[X_AXIS]) > 0.0001) || (fabs(previous_speed[Y_AXIS]) > 0.0001)) {
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vmax_junction = block->nominal_speed;
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//}
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// Estimate a maximum velocity allowed at a joint of two successive segments.
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// If this maximum velocity allowed is lower than the minimum of the entry / exit safe velocities,
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// then the machine is not coasting anymore and the safe entry / exit velocities shall be used.
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float dsx = fabs(current_speed[X_AXIS] - previous_speed[X_AXIS]),
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dsy = fabs(current_speed[Y_AXIS] - previous_speed[Y_AXIS]),
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dsz = fabs(current_speed[Z_AXIS] - previous_speed[Z_AXIS]),
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dse = fabs(current_speed[E_AXIS] - previous_speed[E_AXIS]);
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if (dsx > max_jerk[X_AXIS]) NOMORE(vmax_junction_factor, max_jerk[X_AXIS] / dsx);
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if (dsy > max_jerk[Y_AXIS]) NOMORE(vmax_junction_factor, max_jerk[Y_AXIS] / dsy);
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if (dsz > max_jerk[Z_AXIS]) NOMORE(vmax_junction_factor, max_jerk[Z_AXIS] / dsz);
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if (dse > max_jerk[E_AXIS]) NOMORE(vmax_junction_factor, max_jerk[E_AXIS] / dse);
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vmax_junction = min(previous_nominal_speed, vmax_junction * vmax_junction_factor); // Limit speed to max previous speed
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// The junction velocity will be shared between successive segments. Limit the junction velocity to their minimum.
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bool prev_speed_larger = previous_nominal_speed > block->nominal_speed;
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float smaller_speed_factor = prev_speed_larger ? (block->nominal_speed / previous_nominal_speed) : (previous_nominal_speed / block->nominal_speed);
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// Pick the smaller of the nominal speeds. Higher speed shall not be achieved at the junction during coasting.
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vmax_junction = prev_speed_larger ? block->nominal_speed : previous_nominal_speed;
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// Factor to multiply the previous / current nominal velocities to get componentwise limited velocities.
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float v_factor = 1.f;
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limited = false;
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// Now limit the jerk in all axes.
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LOOP_XYZE(axis) {
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// Limit an axis. We have to differentiate: coasting, reversal of an axis, full stop.
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float v_exit = previous_speed[axis], v_entry = current_speed[axis];
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if (prev_speed_larger) v_exit *= smaller_speed_factor;
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if (limited) {
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v_exit *= v_factor;
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v_entry *= v_factor;
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}
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// Calculate jerk depending on whether the axis is coasting in the same direction or reversing.
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float jerk =
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(v_exit > v_entry) ?
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((v_entry > 0.f || v_exit < 0.f) ?
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// coasting
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(v_exit - v_entry) :
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// axis reversal
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max(v_exit, -v_entry)) :
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// v_exit <= v_entry
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((v_entry < 0.f || v_exit > 0.f) ?
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// coasting
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(v_entry - v_exit) :
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// axis reversal
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max(-v_exit, v_entry));
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if (jerk > max_jerk[axis]) {
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v_factor *= max_jerk[axis] / jerk;
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limited = true;
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}
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}
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if (limited) vmax_junction *= v_factor;
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// Now the transition velocity is known, which maximizes the shared exit / entry velocity while
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// respecting the jerk factors, it may be possible, that applying separate safe exit / entry velocities will achieve faster prints.
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float vmax_junction_threshold = vmax_junction * 0.99f;
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if (previous_safe_speed > vmax_junction_threshold && safe_speed > vmax_junction_threshold) {
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// Not coasting. The machine will stop and start the movements anyway,
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// better to start the segment from start.
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block->flag |= BLOCK_FLAG_START_FROM_FULL_HALT;
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vmax_junction = safe_speed;
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}
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}
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else {
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block->flag |= BLOCK_FLAG_START_FROM_FULL_HALT;
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vmax_junction = safe_speed;
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}
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// Max entry speed of this block equals the max exit speed of the previous block.
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block->max_entry_speed = vmax_junction;
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// Initialize block entry speed. Compute based on deceleration to user-defined MINIMUM_PLANNER_SPEED.
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@ -1109,13 +1193,12 @@ void Planner::_buffer_line(const float &a, const float &b, const float &c, const
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// block nominal speed limits both the current and next maximum junction speeds. Hence, in both
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// the reverse and forward planners, the corresponding block junction speed will always be at the
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// the maximum junction speed and may always be ignored for any speed reduction checks.
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block->flag &= ~BLOCK_FLAG_NOMINAL_LENGTH;
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if (block->nominal_speed <= v_allowable) block->flag |= BLOCK_FLAG_NOMINAL_LENGTH;
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block->flag |= BLOCK_FLAG_RECALCULATE; // Always calculate trapezoid for new block
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block->flag |= BLOCK_FLAG_RECALCULATE | (block->nominal_speed <= v_allowable ? BLOCK_FLAG_NOMINAL_LENGTH : 0);
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// Update previous path unit_vector and nominal speed
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memcpy(previous_speed, current_speed, sizeof(previous_speed));
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previous_nominal_speed = block->nominal_speed;
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previous_safe_speed = safe_speed;
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#if ENABLED(LIN_ADVANCE)
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