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toolhead: Flush lookahead buffer by time 

Use a minimum time window as a heuristic for determining when to try
to lazily flush the lookahead buffer.  In the common case this will
result in more moves processed for each flush and thus reduce the
overall cost of the lookahead processing.

Signed-off-by: Kevin O'Connor <kevin@koconnor.net>
This commit is contained in:
Kevin O'Connor 2017-02-11 12:29:19 -05:00
parent 6179839215
commit 71256f9456
1 changed files with 12 additions and 7 deletions
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19
klippy/toolhead.py
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@ -24,6 +24,7 @@ class Move:
# Extrude only move # Extrude only move
self.move_d = move_d = abs(axes_d[3]) self.move_d = move_d = abs(axes_d[3])
self.is_kinematic_move = False self.is_kinematic_move = False
self.min_move_t = move_d / speed
# Junction speeds are tracked in velocity squared. The # Junction speeds are tracked in velocity squared. The
# delta_v2 is the maximum amount of this squared-velocity that # delta_v2 is the maximum amount of this squared-velocity that
# can change in this move. # can change in this move.
@ -33,7 +34,10 @@ class Move:
self.max_smoothed_v2 = 0. self.max_smoothed_v2 = 0.
self.smooth_delta_v2 = 2.0 * move_d * toolhead.max_accel_to_decel self.smooth_delta_v2 = 2.0 * move_d * toolhead.max_accel_to_decel
def limit_speed(self, speed, accel): def limit_speed(self, speed, accel):
self.max_cruise_v2 = min(self.max_cruise_v2, speed**2) speed2 = speed**2
if speed2 < self.max_cruise_v2:
self.max_cruise_v2 = speed2
self.min_move_t = self.move_d / speed
self.accel = min(self.accel, accel) self.accel = min(self.accel, accel)
self.delta_v2 = 2.0 * self.move_d * self.accel self.delta_v2 = 2.0 * self.move_d * self.accel
self.smooth_delta_v2 = min(self.smooth_delta_v2, self.delta_v2) self.smooth_delta_v2 = min(self.smooth_delta_v2, self.delta_v2)
@ -87,6 +91,8 @@ class Move:
self.toolhead.update_move_time( self.toolhead.update_move_time(
self.accel_t + self.cruise_t + self.decel_t) self.accel_t + self.cruise_t + self.decel_t)
LOOKAHEAD_FLUSH_TIME = 0.250
# Class to track a list of pending move requests and to facilitate # Class to track a list of pending move requests and to facilitate
# "look-ahead" across moves to reduce acceleration between moves. # "look-ahead" across moves to reduce acceleration between moves.
class MoveQueue: class MoveQueue:
@ -95,12 +101,14 @@ class MoveQueue:
self.queue = [] self.queue = []
self.leftover = 0 self.leftover = 0
self.next_start_v2 = 0. self.next_start_v2 = 0.
self.junction_flush = 0. self.junction_flush = LOOKAHEAD_FLUSH_TIME
def reset(self): def reset(self):
del self.queue[:] del self.queue[:]
self.leftover = 0 self.leftover = 0
self.next_start_v2 = 0. self.next_start_v2 = 0.
self.junction_flush = LOOKAHEAD_FLUSH_TIME
def flush(self, lazy=False): def flush(self, lazy=False):
self.junction_flush = LOOKAHEAD_FLUSH_TIME
update_flush_count = lazy update_flush_count = lazy
queue = self.queue queue = self.queue
flush_count = len(queue) flush_count = len(queue)
@ -143,7 +151,7 @@ class MoveQueue:
next_end_v2 = start_v2 next_end_v2 = start_v2
next_smoothed_v2 = smoothed_v2 next_smoothed_v2 = smoothed_v2
if update_flush_count: if update_flush_count:
flush_count = 0 return
# Allow extruder to do its lookahead # Allow extruder to do its lookahead
move_count = self.extruder_lookahead(queue, flush_count, lazy) move_count = self.extruder_lookahead(queue, flush_count, lazy)
# Generate step times for all moves ready to be flushed # Generate step times for all moves ready to be flushed
@ -152,15 +160,12 @@ class MoveQueue:
# Remove processed moves from the queue # Remove processed moves from the queue
self.leftover = flush_count - move_count self.leftover = flush_count - move_count
del queue[:move_count] del queue[:move_count]
if queue:
self.junction_flush = 2. * queue[-1].max_cruise_v2
def add_move(self, move): def add_move(self, move):
self.queue.append(move) self.queue.append(move)
if len(self.queue) == 1: if len(self.queue) == 1:
self.junction_flush = 2. * move.max_cruise_v2
return return
move.calc_junction(self.queue[-2]) move.calc_junction(self.queue[-2])
self.junction_flush -= move.smooth_delta_v2 self.junction_flush -= move.min_move_t
if self.junction_flush <= 0.: if self.junction_flush <= 0.:
# There are enough queued moves to return to zero velocity # There are enough queued moves to return to zero velocity
# from the first move's maximum possible velocity, so at # from the first move's maximum possible velocity, so at