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
parent
c847606311
commit
dc37a07a8e
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@ -90,6 +90,11 @@ step_distance: .004242
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max_velocity: 200000
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max_accel: 3000
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# The remaining variables describe the extruder heater
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pressure_advance: 0.0
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# The amount of raw filament to push into the extruder during
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# extruder acceleration. An equal amount of filament is retracted
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# during deceleration. It is measured in millimeters per
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# millimeter/second
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heater_pin: ar4
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# PWM output pin controlling the heater
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thermistor_pin: analog1
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@ -1,7 +1,7 @@
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# Support for Makergear M2 printers circa 2012 that have the RAMBo
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# v1.0d electronics. The electronics use Allegro A4984 stepper
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# drivers with 1/8th micro-stepping. To use this config, the firmware
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# should be compiled for the AVR atmega2560.
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# v1.0d electronics along with the V3A extruder. The electronics use
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# Allegro A4984 stepper drivers with 1/8th micro-stepping. To use
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# this config, the firmware should be compiled for the AVR atmega2560.
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[stepper_x]
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step_pin: PC0
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@ -50,6 +50,7 @@ enable_pin: !PA4
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step_distance: .004242
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max_velocity: 200000
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max_accel: 3000
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pressure_advance: 0.07
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heater_pin: PH6
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thermistor_pin: PF0
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thermistor_type: EPCOS 100K B57560G104F
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@ -11,7 +11,9 @@ class PrinterExtruder:
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cfg = config.getsection('extruder')
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self.heater = heater.PrinterHeater(printer, cfg)
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self.stepper = stepper.PrinterStepper(printer, cfg)
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self.pressure_advance = config.getfloat('pressure_advance', 0.)
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self.stepper_pos = 0
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self.extrude_pos = 0.
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def build_config(self):
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self.heater.build_config()
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self.stepper.set_max_jerk(9999999.9)
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@ -21,43 +23,105 @@ class PrinterExtruder:
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def motor_off(self, move_time):
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self.stepper.motor_enable(move_time, 0)
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def move(self, move_time, move):
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move_d = move.move_d
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inv_accel = 1. / move.accel
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new_step_pos = int(move.pos[3]*self.stepper.inv_step_dist + 0.5)
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start_v, cruise_v, end_v = move.start_v, move.cruise_v, move.end_v
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accel_t, cruise_t, decel_t = move.accel_t, move.cruise_t, move.decel_t
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accel_d = move.accel_r * move_d
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cruise_d = move.cruise_r * move_d
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decel_d = move.decel_r * move_d
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retract_t = retract_d = retract_v = 0.
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decel_v = cruise_v
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# Update for pressure advance
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if (move.axes_d[3] >= 0. and (move.axes_d[0] or move.axes_d[1])
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and self.pressure_advance):
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# Increase accel_d and start_v when accelerating
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extra_accel_d = (cruise_v - start_v) * self.pressure_advance
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accel_d += extra_accel_d
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if accel_t:
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start_v += extra_accel_d / accel_t
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# Update decel and retract parameters when decelerating
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if decel_t:
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extra_decel_d = (cruise_v - end_v) * self.pressure_advance
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extra_decel_v = extra_decel_d / decel_t
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decel_v -= extra_decel_v
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end_v -= extra_decel_v
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if decel_v <= 0.:
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retract_t = decel_t
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retract_d = -(end_v + decel_v) * 0.5 * decel_t
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retract_v = -decel_v
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decel_t = decel_d = 0.
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elif end_v < 0.:
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retract_t = -end_v * inv_accel
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retract_d = -end_v * 0.5 * retract_t
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decel_t -= retract_t
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decel_d = decel_v * 0.5 * decel_t
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else:
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decel_d -= extra_decel_d
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# Determine regular steps
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extrude_r = move.axes_d[3] / move_d
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forward_d = accel_d + cruise_d + decel_d
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self.extrude_pos += forward_d * extrude_r
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new_step_pos = int(self.extrude_pos*self.stepper.inv_step_dist + 0.5)
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steps = new_step_pos - self.stepper_pos
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if not steps:
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return
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if steps:
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self.stepper_pos = new_step_pos
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sdir = 0
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if steps < 0:
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sdir = 1
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steps = -steps
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clock_offset, clock_freq, so = self.stepper.prep_move(sdir, move_time)
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clock_offset, clock_freq, so = self.stepper.prep_move(
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sdir, move_time)
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step_dist = move.move_d / steps
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step_dist = forward_d / steps
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inv_step_dist = 1. / step_dist
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step_offset = 0.5
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# Acceleration steps
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#t = sqrt(2*pos/accel + (start_v/accel)**2) - start_v/accel
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accel_clock_offset = move.start_v * inv_accel * clock_freq
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accel_clock_offset = start_v * inv_accel * clock_freq
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accel_sqrt_offset = accel_clock_offset**2
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accel_multiplier = 2.0 * step_dist * inv_accel * clock_freq**2
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accel_steps = move.accel_r * steps
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accel_steps = accel_d * inv_step_dist
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step_offset = so.step_sqrt(
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accel_steps, step_offset, clock_offset - accel_clock_offset
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, accel_sqrt_offset, accel_multiplier)
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clock_offset += move.accel_t * clock_freq
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clock_offset += accel_t * clock_freq
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# Cruising steps
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#t = pos/cruise_v
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cruise_multiplier = step_dist * clock_freq / move.cruise_v
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cruise_steps = move.cruise_r * steps
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cruise_multiplier = step_dist * clock_freq / cruise_v
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cruise_steps = cruise_d * inv_step_dist
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step_offset = so.step_factor(
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cruise_steps, step_offset, clock_offset, cruise_multiplier)
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clock_offset += move.cruise_t * clock_freq
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clock_offset += cruise_t * clock_freq
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# Deceleration steps
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#t = cruise_v/accel - sqrt((cruise_v/accel)**2 - 2*pos/accel)
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decel_clock_offset = move.cruise_v * inv_accel * clock_freq
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decel_clock_offset = decel_v * inv_accel * clock_freq
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decel_sqrt_offset = decel_clock_offset**2
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decel_steps = move.decel_r * steps
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decel_steps = decel_d * inv_step_dist
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so.step_sqrt(
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decel_steps, step_offset, clock_offset + decel_clock_offset
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, decel_sqrt_offset, -accel_multiplier)
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# Determine retract steps
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self.extrude_pos -= retract_d * extrude_r
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new_step_pos = int(self.extrude_pos*self.stepper.inv_step_dist + 0.5)
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steps = self.stepper_pos - new_step_pos
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if steps:
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self.stepper_pos = new_step_pos
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clock_offset, clock_freq, so = self.stepper.prep_move(
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1, move_time+accel_t+cruise_t+decel_t)
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step_dist = retract_d / steps
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# Acceleration steps
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#t = sqrt(2*pos/accel + (start_v/accel)**2) - start_v/accel
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accel_clock_offset = retract_v * inv_accel * clock_freq
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accel_sqrt_offset = accel_clock_offset**2
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accel_multiplier = 2.0 * step_dist * inv_accel * clock_freq**2
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so.step_sqrt(steps, 0.5, clock_offset - accel_clock_offset
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, accel_sqrt_offset, accel_multiplier)
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