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| author | Kevin O'Connor <kevin@koconnor.net> | 2016-10-25 21:06:20 -0400 |
|---|---|---|
| committer | Kevin O'Connor <kevin@koconnor.net> | 2016-10-31 11:14:28 -0400 |
| commit | 8f331f08d262cdc9e641d333e17098a94cf13fd5 (patch) | |
| tree | 3243b7a0e3818369e1f0cd99137822a0ea6327a8 | |
| parent | f0cefebff7c9077dd5f39a9d265cada04b76e6b6 (diff) | |
| download | kutter-8f331f08d262cdc9e641d333e17098a94cf13fd5.tar.gz kutter-8f331f08d262cdc9e641d333e17098a94cf13fd5.tar.xz kutter-8f331f08d262cdc9e641d333e17098a94cf13fd5.zip | |
extruder: Determine start step offset using last commanded position
The existing code calculates the number of steps in a move and then
spreads them out evenly throughout that move. Change the code so that
step timing is based on where the head is commanded to be relative to
the stepper step locations. This makes the timing more accurate - in
particular the stepper velocities will be more accurate during
cornering introduced by the lookahead code. It also results in
slightly smoother stepper motion which results in better step
compression.
Signed-off-by: Kevin O'Connor <kevin@koconnor.net>
| -rw-r--r-- | klippy/extruder.py | 26 |
1 files changed, 16 insertions, 10 deletions
diff --git a/klippy/extruder.py b/klippy/extruder.py index 181fd57c..198a89ed 100644 --- a/klippy/extruder.py +++ b/klippy/extruder.py @@ -73,20 +73,23 @@ class PrinterExtruder: # Determine regular steps extrude_r = move.axes_d[3] / move_d forward_d = accel_d + cruise_d + decel_d - self.extrude_pos += forward_d * extrude_r - new_step_pos = int(self.extrude_pos*self.stepper.inv_step_dist + 0.5) - steps = new_step_pos - self.stepper_pos - if steps: + start_pos = self.extrude_pos + end_pos = start_pos + forward_d * extrude_r + inv_step_dist = self.stepper.inv_step_dist + new_step_pos = int(end_pos*inv_step_dist + 0.5) + if new_step_pos != self.stepper_pos: + steps = forward_d * extrude_r * inv_step_dist + step_offset = self.stepper_pos - start_pos * inv_step_dist + 0.5 self.stepper_pos = new_step_pos sdir = 0 if steps < 0: sdir = 1 steps = -steps + step_offset = 1. - step_offset mcu_time, so = self.stepper.prep_move(move_time, sdir) move_step_d = forward_d / steps inv_move_step_d = 1. / move_step_d - step_offset = 0.5 # Acceleration steps #t = sqrt(2*pos/accel + (start_v/accel)**2) - start_v/accel @@ -115,10 +118,12 @@ class PrinterExtruder: , decel_sqrt_offset, -accel_multiplier) # Determine retract steps - self.extrude_pos -= retract_d * extrude_r - new_step_pos = int(self.extrude_pos*self.stepper.inv_step_dist + 0.5) - steps = self.stepper_pos - new_step_pos - if steps: + start_pos = end_pos + end_pos -= retract_d * extrude_r + new_step_pos = int(end_pos*inv_step_dist + 0.5) + if new_step_pos != self.stepper_pos: + steps = retract_d * extrude_r * inv_step_dist + step_offset = start_pos * inv_step_dist - self.stepper_pos + 0.5 self.stepper_pos = new_step_pos mcu_time, so = self.stepper.prep_move( move_time+accel_t+cruise_t+decel_t, 1) @@ -130,5 +135,6 @@ class PrinterExtruder: accel_time_offset = retract_v * inv_accel accel_sqrt_offset = accel_time_offset**2 accel_multiplier = 2.0 * move_step_d * inv_accel - so.step_sqrt(mcu_time - accel_time_offset, steps, 0.5 + so.step_sqrt(mcu_time - accel_time_offset, steps, step_offset , accel_sqrt_offset, accel_multiplier) + self.extrude_pos = end_pos |