406 lines
18 KiB
Python
406 lines
18 KiB
Python
# Code for coordinating events on the printer toolhead
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#
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# Copyright (C) 2016 Kevin O'Connor <kevin@koconnor.net>
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#
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# This file may be distributed under the terms of the GNU GPLv3 license.
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import math, logging
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import homing, cartesian, corexy, delta, extruder
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# Common suffixes: _d is distance (in mm), _v is velocity (in
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# mm/second), _v2 is velocity squared (mm^2/s^2), _t is time (in
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# seconds), _r is ratio (scalar between 0.0 and 1.0)
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# Class to track each move request
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class Move:
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def __init__(self, toolhead, start_pos, end_pos, speed):
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self.toolhead = toolhead
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self.start_pos = tuple(start_pos)
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self.end_pos = tuple(end_pos)
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self.accel = toolhead.max_accel
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self.is_kinematic_move = True
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self.axes_d = axes_d = [end_pos[i] - start_pos[i] for i in (0, 1, 2, 3)]
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self.move_d = move_d = math.sqrt(sum([d*d for d in axes_d[:3]]))
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if not move_d:
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# Extrude only move
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self.move_d = move_d = abs(axes_d[3])
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self.is_kinematic_move = False
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self.min_move_t = move_d / speed
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# Junction speeds are tracked in velocity squared. The
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# delta_v2 is the maximum amount of this squared-velocity that
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# can change in this move.
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self.max_start_v2 = 0.
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self.max_cruise_v2 = speed**2
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self.delta_v2 = 2.0 * move_d * self.accel
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self.max_smoothed_v2 = 0.
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self.smooth_delta_v2 = 2.0 * move_d * toolhead.max_accel_to_decel
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def limit_speed(self, speed, accel):
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speed2 = speed**2
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if speed2 < self.max_cruise_v2:
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self.max_cruise_v2 = speed2
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self.min_move_t = self.move_d / speed
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self.accel = min(self.accel, accel)
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self.delta_v2 = 2.0 * self.move_d * self.accel
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self.smooth_delta_v2 = min(self.smooth_delta_v2, self.delta_v2)
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def calc_junction(self, prev_move):
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if not self.is_kinematic_move or not prev_move.is_kinematic_move:
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return
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# Allow extruder to calculate its maximum junction
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extruder_v2 = self.toolhead.extruder.calc_junction(prev_move, self)
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# Find max velocity using approximated centripetal velocity as
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# described at:
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# https://onehossshay.wordpress.com/2011/09/24/improving_grbl_cornering_algorithm/
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axes_d = self.axes_d
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prev_axes_d = prev_move.axes_d
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junction_cos_theta = -((axes_d[0] * prev_axes_d[0]
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+ axes_d[1] * prev_axes_d[1]
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+ axes_d[2] * prev_axes_d[2])
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/ (self.move_d * prev_move.move_d))
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if junction_cos_theta > 0.999999:
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return
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junction_cos_theta = max(junction_cos_theta, -0.999999)
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sin_theta_d2 = math.sqrt(0.5*(1.0-junction_cos_theta))
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R = self.toolhead.junction_deviation * sin_theta_d2 / (1. - sin_theta_d2)
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self.max_start_v2 = min(
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R * self.accel, R * prev_move.accel, extruder_v2
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, self.max_cruise_v2, prev_move.max_cruise_v2
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, prev_move.max_start_v2 + prev_move.delta_v2)
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self.max_smoothed_v2 = min(
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self.max_start_v2
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, prev_move.max_smoothed_v2 + prev_move.smooth_delta_v2)
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def set_junction(self, start_v2, cruise_v2, end_v2):
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# Determine accel, cruise, and decel portions of the move distance
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inv_delta_v2 = 1. / self.delta_v2
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self.accel_r = accel_r = (cruise_v2 - start_v2) * inv_delta_v2
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self.decel_r = decel_r = (cruise_v2 - end_v2) * inv_delta_v2
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self.cruise_r = cruise_r = 1. - accel_r - decel_r
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# Determine move velocities
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self.start_v = start_v = math.sqrt(start_v2)
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self.cruise_v = cruise_v = math.sqrt(cruise_v2)
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self.end_v = end_v = math.sqrt(end_v2)
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# Determine time spent in each portion of move (time is the
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# distance divided by average velocity)
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self.accel_t = accel_r * self.move_d / ((start_v + cruise_v) * 0.5)
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self.cruise_t = cruise_r * self.move_d / cruise_v
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self.decel_t = decel_r * self.move_d / ((end_v + cruise_v) * 0.5)
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def move(self):
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# Generate step times for the move
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next_move_time = self.toolhead.get_next_move_time()
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if self.is_kinematic_move:
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self.toolhead.kin.move(next_move_time, self)
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if self.axes_d[3]:
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self.toolhead.extruder.move(next_move_time, self)
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self.toolhead.update_move_time(
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self.accel_t + self.cruise_t + self.decel_t)
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LOOKAHEAD_FLUSH_TIME = 0.250
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# Class to track a list of pending move requests and to facilitate
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# "look-ahead" across moves to reduce acceleration between moves.
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class MoveQueue:
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def __init__(self):
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self.extruder_lookahead = None
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self.queue = []
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self.leftover = 0
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self.junction_flush = LOOKAHEAD_FLUSH_TIME
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def reset(self):
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del self.queue[:]
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self.leftover = 0
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self.junction_flush = LOOKAHEAD_FLUSH_TIME
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def set_flush_time(self, flush_time):
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self.junction_flush = flush_time
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def set_extruder(self, extruder):
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self.extruder_lookahead = extruder.lookahead
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def flush(self, lazy=False):
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self.junction_flush = LOOKAHEAD_FLUSH_TIME
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update_flush_count = lazy
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queue = self.queue
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flush_count = len(queue)
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# Traverse queue from last to first move and determine maximum
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# junction speed assuming the robot comes to a complete stop
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# after the last move.
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delayed = []
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next_end_v2 = next_smoothed_v2 = peak_cruise_v2 = 0.
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for i in range(flush_count-1, self.leftover-1, -1):
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move = queue[i]
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reachable_start_v2 = next_end_v2 + move.delta_v2
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start_v2 = min(move.max_start_v2, reachable_start_v2)
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reachable_smoothed_v2 = next_smoothed_v2 + move.smooth_delta_v2
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smoothed_v2 = min(move.max_smoothed_v2, reachable_smoothed_v2)
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if smoothed_v2 < reachable_smoothed_v2:
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# It's possible for this move to accelerate
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if (smoothed_v2 + move.smooth_delta_v2 > next_smoothed_v2
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or delayed):
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# This move can decelerate or this is a full accel
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# move after a full decel move
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if update_flush_count and peak_cruise_v2:
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flush_count = i
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update_flush_count = False
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peak_cruise_v2 = min(move.max_cruise_v2, (
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smoothed_v2 + reachable_smoothed_v2) * .5)
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if delayed:
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# Propagate peak_cruise_v2 to any delayed moves
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if not update_flush_count and i < flush_count:
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for m, ms_v2, me_v2 in delayed:
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mc_v2 = min(peak_cruise_v2, ms_v2)
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m.set_junction(min(ms_v2, mc_v2), mc_v2
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, min(me_v2, mc_v2))
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del delayed[:]
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if not update_flush_count and i < flush_count:
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cruise_v2 = min((start_v2 + reachable_start_v2) * .5
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, move.max_cruise_v2, peak_cruise_v2)
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move.set_junction(min(start_v2, cruise_v2), cruise_v2
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, min(next_end_v2, cruise_v2))
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else:
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# Delay calculating this move until peak_cruise_v2 is known
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delayed.append((move, start_v2, next_end_v2))
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next_end_v2 = start_v2
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next_smoothed_v2 = smoothed_v2
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if update_flush_count:
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return
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# Allow extruder to do its lookahead
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move_count = self.extruder_lookahead(queue, flush_count, lazy)
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# Generate step times for all moves ready to be flushed
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for move in queue[:move_count]:
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move.move()
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# Remove processed moves from the queue
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self.leftover = flush_count - move_count
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del queue[:move_count]
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def add_move(self, move):
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self.queue.append(move)
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if len(self.queue) == 1:
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return
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move.calc_junction(self.queue[-2])
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self.junction_flush -= move.min_move_t
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if self.junction_flush <= 0.:
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# There are enough queued moves to return to zero velocity
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# from the first move's maximum possible velocity, so at
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# least one move can be flushed.
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self.flush(lazy=True)
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STALL_TIME = 0.100
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# Main code to track events (and their timing) on the printer toolhead
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class ToolHead:
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def __init__(self, printer, config):
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self.printer = printer
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self.reactor = printer.reactor
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self.mcu = printer.objects['mcu']
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self.max_velocity = config.getfloat('max_velocity', above=0.)
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self.max_accel = config.getfloat('max_accel', above=0.)
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self.max_accel_to_decel = config.getfloat(
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'max_accel_to_decel', self.max_accel * 0.5
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, above=0., maxval=self.max_accel)
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self.junction_deviation = config.getfloat(
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'junction_deviation', 0.02, above=0.)
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self.move_queue = MoveQueue()
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self.commanded_pos = [0., 0., 0., 0.]
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# Print time tracking
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self.buffer_time_low = config.getfloat(
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'buffer_time_low', 1.000, above=0.)
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self.buffer_time_high = config.getfloat(
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'buffer_time_high', 2.000, above=self.buffer_time_low)
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self.buffer_time_start = config.getfloat(
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'buffer_time_start', 0.250, above=0.)
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self.move_flush_time = config.getfloat(
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'move_flush_time', 0.050, above=0.)
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self.print_time = 0.
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self.last_print_end_time = self.reactor.monotonic()
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self.need_check_stall = -1.
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self.print_stall = 0
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self.synch_print_time = True
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self.forced_synch = False
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self.flush_timer = self.reactor.register_timer(self._flush_handler)
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self.move_queue.set_flush_time(self.buffer_time_high)
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# Motor off tracking
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self.motor_off_time = config.getfloat(
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'motor_off_time', 600.000, minval=0.)
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self.motor_off_timer = self.reactor.register_timer(
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self._motor_off_handler)
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# Create kinematics class
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self.extruder = extruder.DummyExtruder()
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self.move_queue.set_extruder(self.extruder)
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kintypes = {'cartesian': cartesian.CartKinematics,
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'corexy': corexy.CoreXYKinematics,
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'delta': delta.DeltaKinematics}
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self.kin = config.getchoice('kinematics', kintypes)(
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self, printer, config)
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# Print time tracking
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def update_move_time(self, movetime):
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self.print_time += movetime
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flush_to_time = self.print_time - self.move_flush_time
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self.mcu.flush_moves(flush_to_time)
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def get_next_move_time(self):
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if self.synch_print_time:
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curtime = self.reactor.monotonic()
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if self.print_time:
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buffer_time = self.mcu.get_print_buffer_time(
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curtime, self.print_time)
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self.print_time += max(self.buffer_time_start - buffer_time, 0.)
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if self.forced_synch:
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self.print_stall += 1
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self.forced_synch = False
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else:
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self.mcu.set_print_start_time(curtime)
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self.print_time = self.buffer_time_start
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self._reset_motor_off()
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self.reactor.update_timer(self.flush_timer, self.reactor.NOW)
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self.synch_print_time = False
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return self.print_time
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def _flush_lookahead(self, must_synch=False):
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synch_print_time = self.synch_print_time
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self.move_queue.flush()
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if synch_print_time or must_synch:
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self.synch_print_time = True
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self.move_queue.set_flush_time(self.buffer_time_high)
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self.mcu.flush_moves(self.print_time)
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def get_last_move_time(self):
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self._flush_lookahead()
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return self.get_next_move_time()
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def reset_print_time(self):
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self._flush_lookahead(must_synch=True)
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self.print_time = 0.
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self.last_print_end_time = self.reactor.monotonic()
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self.need_check_stall = -1.
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self.forced_synch = False
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self._reset_motor_off()
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def _check_stall(self):
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eventtime = self.reactor.monotonic()
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if not self.print_time:
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# Building initial queue - make sure to flush on idle input
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self.reactor.update_timer(self.flush_timer, eventtime + 0.100)
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return
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# Check if there are lots of queued moves and stall if so
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while 1:
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buffer_time = self.mcu.get_print_buffer_time(
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eventtime, self.print_time)
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stall_time = buffer_time - self.buffer_time_high
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if stall_time <= 0.:
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break
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eventtime = self.reactor.pause(eventtime + stall_time)
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if not self.print_time:
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return
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self.need_check_stall = self.print_time - stall_time + 0.100
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def _flush_handler(self, eventtime):
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try:
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if not self.print_time:
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# Input idled before filling lookahead queue - flush it
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self._flush_lookahead()
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if not self.print_time:
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return self.reactor.NEVER
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print_time = self.print_time
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buffer_time = self.mcu.get_print_buffer_time(eventtime, print_time)
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if buffer_time > self.buffer_time_low:
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# Running normally - reschedule check
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return eventtime + buffer_time - self.buffer_time_low
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# Under ran low buffer mark - flush lookahead queue
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self._flush_lookahead(must_synch=True)
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if print_time != self.print_time:
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# Flushed something - retry
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self.forced_synch = True
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return self.reactor.NOW
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if buffer_time > 0.:
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# Wait for buffer to fully empty
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return eventtime + buffer_time
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self.reset_print_time()
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except:
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logging.exception("Exception in flush_handler")
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self.force_shutdown()
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return self.reactor.NEVER
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# Motor off timer
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def _reset_motor_off(self):
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if not self.print_time:
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waketime = self.reactor.monotonic() + self.motor_off_time
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else:
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waketime = self.reactor.NEVER
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self.reactor.update_timer(self.motor_off_timer, waketime)
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def _motor_off_handler(self, eventtime):
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try:
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self.motor_off()
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self.reset_print_time()
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except:
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logging.exception("Exception in motor_off_handler")
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self.force_shutdown()
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return self.reactor.NEVER
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# Movement commands
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def get_position(self):
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return list(self.commanded_pos)
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def set_position(self, newpos):
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self._flush_lookahead()
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self.commanded_pos[:] = newpos
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self.kin.set_position(newpos)
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def move(self, newpos, speed):
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speed = min(speed, self.max_velocity)
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move = Move(self, self.commanded_pos, newpos, speed)
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if not move.move_d:
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return
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if move.is_kinematic_move:
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self.kin.check_move(move)
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if move.axes_d[3]:
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self.extruder.check_move(move)
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self.commanded_pos[:] = newpos
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self.move_queue.add_move(move)
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if self.print_time > self.need_check_stall:
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self._check_stall()
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def home(self, homing_state):
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self.kin.home(homing_state)
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def dwell(self, delay):
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self.get_last_move_time()
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self.update_move_time(delay)
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self._check_stall()
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def motor_off(self):
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self.dwell(STALL_TIME)
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last_move_time = self.get_last_move_time()
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self.kin.motor_off(last_move_time)
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self.extruder.motor_off(last_move_time)
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self.dwell(STALL_TIME)
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logging.debug('; Max time of %f' % (last_move_time,))
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def wait_moves(self):
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self._flush_lookahead()
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if self.printer.get_start_args().get('debugoutput') is not None:
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return
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eventtime = self.reactor.monotonic()
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while self.print_time:
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eventtime = self.reactor.pause(eventtime + 0.100)
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def query_endstops(self):
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last_move_time = self.get_last_move_time()
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try:
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return self.kin.query_endstops(last_move_time)
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except self.mcu.error as e:
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raise homing.EndstopError(str(e))
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def set_extruder(self, extruder):
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last_move_time = self.get_last_move_time()
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self.extruder.set_active(last_move_time, False)
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extrude_pos = extruder.set_active(last_move_time, True)
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self.extruder = extruder
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self.move_queue.set_extruder(extruder)
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self.commanded_pos[3] = extrude_pos
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# Misc commands
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def stats(self, eventtime):
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buffer_time = 0.
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print_time = self.print_time
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if print_time:
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is_active = True
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buffer_time = max(0., self.mcu.get_print_buffer_time(
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eventtime, print_time))
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else:
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is_active = eventtime < self.last_print_end_time + 60.
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return is_active, "print_time=%.3f buffer_time=%.3f print_stall=%d" % (
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print_time, buffer_time, self.print_stall)
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def force_shutdown(self):
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try:
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self.mcu.force_shutdown()
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self.move_queue.reset()
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self.reset_print_time()
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except:
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logging.exception("Exception in force_shutdown")
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def get_max_velocity(self):
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return self.max_velocity, self.max_accel
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def get_max_axis_halt(self, max_accel):
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# Determine the maximum velocity a cartesian axis could halt
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# at due to the junction_deviation setting. The 8.0 was
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# determined experimentally.
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return math.sqrt(8. * self.junction_deviation * max_accel)
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def add_printer_objects(printer, config):
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printer.add_object('toolhead', ToolHead(printer, config))
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