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extruder: Add support for "pressure advance" on extrusion 

Add a config option to define an amount of additional filament to feed
into the extruder during acceleration and deceleration of the
extruder.  This can help ensure plastic is deposited in the correct
places during a print.

Signed-off-by: Kevin O'Connor <kevin@koconnor.net>
This commit is contained in:
Kevin O'Connor 2016-07-16 19:58:41 -04:00
parent c847606311
commit dc37a07a8e
3 changed files with 109 additions and 39 deletions
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5
config/example.cfg
View File

@ -90,6 +90,11 @@ step_distance: .004242
max_velocity: 200000
max_accel: 3000
# The remaining variables describe the extruder heater
pressure_advance: 0.0
# The amount of raw filament to push into the extruder during
# extruder acceleration. An equal amount of filament is retracted
# during deceleration. It is measured in millimeters per
# millimeter/second
heater_pin: ar4
# PWM output pin controlling the heater
thermistor_pin: analog1

7
config/makergear-m2-2012.cfg
View File

@ -1,7 +1,7 @@
# Support for Makergear M2 printers circa 2012 that have the RAMBo
# v1.0d electronics. The electronics use Allegro A4984 stepper
# drivers with 1/8th micro-stepping. To use this config, the firmware
# should be compiled for the AVR atmega2560.
# v1.0d electronics along with the V3A extruder. The electronics use
# Allegro A4984 stepper drivers with 1/8th micro-stepping. To use
# this config, the firmware should be compiled for the AVR atmega2560.
[stepper_x]
step_pin: PC0
@ -50,6 +50,7 @@ enable_pin: !PA4
step_distance: .004242
max_velocity: 200000
max_accel: 3000
pressure_advance: 0.07
heater_pin: PH6
thermistor_pin: PF0
thermistor_type: EPCOS 100K B57560G104F

90
klippy/extruder.py
View File

@ -11,7 +11,9 @@ class PrinterExtruder:
cfg = config.getsection('extruder')
self.heater = heater.PrinterHeater(printer, cfg)
self.stepper = stepper.PrinterStepper(printer, cfg)
self.pressure_advance = config.getfloat('pressure_advance', 0.)
self.stepper_pos = 0
self.extrude_pos = 0.
def build_config(self):
self.heater.build_config()
self.stepper.set_max_jerk(9999999.9)
@ -21,43 +23,105 @@ class PrinterExtruder:
def motor_off(self, move_time):
self.stepper.motor_enable(move_time, 0)
def move(self, move_time, move):
move_d = move.move_d
inv_accel = 1. / move.accel
new_step_pos = int(move.pos[3]*self.stepper.inv_step_dist + 0.5)
start_v, cruise_v, end_v = move.start_v, move.cruise_v, move.end_v
accel_t, cruise_t, decel_t = move.accel_t, move.cruise_t, move.decel_t
accel_d = move.accel_r * move_d
cruise_d = move.cruise_r * move_d
decel_d = move.decel_r * move_d
retract_t = retract_d = retract_v = 0.
decel_v = cruise_v
# Update for pressure advance
if (move.axes_d[3] >= 0. and (move.axes_d[0] or move.axes_d[1])
and self.pressure_advance):
# Increase accel_d and start_v when accelerating
extra_accel_d = (cruise_v - start_v) * self.pressure_advance
accel_d += extra_accel_d
if accel_t:
start_v += extra_accel_d / accel_t
# Update decel and retract parameters when decelerating
if decel_t:
extra_decel_d = (cruise_v - end_v) * self.pressure_advance
extra_decel_v = extra_decel_d / decel_t
decel_v -= extra_decel_v
end_v -= extra_decel_v
if decel_v <= 0.:
retract_t = decel_t
retract_d = -(end_v + decel_v) * 0.5 * decel_t
retract_v = -decel_v
decel_t = decel_d = 0.
elif end_v < 0.:
retract_t = -end_v * inv_accel
retract_d = -end_v * 0.5 * retract_t
decel_t -= retract_t
decel_d = decel_v * 0.5 * decel_t
else:
decel_d -= extra_decel_d
# 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 not steps:
return
if steps:
self.stepper_pos = new_step_pos
sdir = 0
if steps < 0:
sdir = 1
steps = -steps
clock_offset, clock_freq, so = self.stepper.prep_move(sdir, move_time)
clock_offset, clock_freq, so = self.stepper.prep_move(
sdir, move_time)
step_dist = move.move_d / steps
step_dist = forward_d / steps
inv_step_dist = 1. / step_dist
step_offset = 0.5
# Acceleration steps
#t = sqrt(2*pos/accel + (start_v/accel)**2) - start_v/accel
accel_clock_offset = move.start_v * inv_accel * clock_freq
accel_clock_offset = start_v * inv_accel * clock_freq
accel_sqrt_offset = accel_clock_offset**2
accel_multiplier = 2.0 * step_dist * inv_accel * clock_freq**2
accel_steps = move.accel_r * steps
accel_steps = accel_d * inv_step_dist
step_offset = so.step_sqrt(
accel_steps, step_offset, clock_offset - accel_clock_offset
, accel_sqrt_offset, accel_multiplier)
clock_offset += move.accel_t * clock_freq
clock_offset += accel_t * clock_freq
# Cruising steps
#t = pos/cruise_v
cruise_multiplier = step_dist * clock_freq / move.cruise_v
cruise_steps = move.cruise_r * steps
cruise_multiplier = step_dist * clock_freq / cruise_v
cruise_steps = cruise_d * inv_step_dist
step_offset = so.step_factor(
cruise_steps, step_offset, clock_offset, cruise_multiplier)
clock_offset += move.cruise_t * clock_freq
clock_offset += cruise_t * clock_freq
# Deceleration steps
#t = cruise_v/accel - sqrt((cruise_v/accel)**2 - 2*pos/accel)
decel_clock_offset = move.cruise_v * inv_accel * clock_freq
decel_clock_offset = decel_v * inv_accel * clock_freq
decel_sqrt_offset = decel_clock_offset**2
decel_steps = move.decel_r * steps
decel_steps = decel_d * inv_step_dist
so.step_sqrt(
decel_steps, step_offset, clock_offset + decel_clock_offset
, 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:
self.stepper_pos = new_step_pos
clock_offset, clock_freq, so = self.stepper.prep_move(
1, move_time+accel_t+cruise_t+decel_t)
step_dist = retract_d / steps
# Acceleration steps
#t = sqrt(2*pos/accel + (start_v/accel)**2) - start_v/accel
accel_clock_offset = retract_v * inv_accel * clock_freq
accel_sqrt_offset = accel_clock_offset**2
accel_multiplier = 2.0 * step_dist * inv_accel * clock_freq**2
so.step_sqrt(steps, 0.5, clock_offset - accel_clock_offset
, accel_sqrt_offset, accel_multiplier)