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#!/usr/bin/env python2
# Generate extruder pressure advance motion graphs
#
# Copyright (C) 2019 Kevin O'Connor <kevin@koconnor.net>
#
# This file may be distributed under the terms of the GNU GPLv3 license.
import math, optparse, datetime
import matplotlib
SEG_TIME = .000100
INV_SEG_TIME = 1. / SEG_TIME
######################################################################
# Basic trapezoid motion
######################################################################
# List of moves: [(start_v, end_v, move_t), ...]
Moves = [
(0., 0., .200),
(0., 100., None), (100., 100., .200), (100., 60., None),
(60., 100., None), (100., 100., .200), (100., 0., None),
(0., 0., .300)
]
EXTRUDE_R = (.4 * .4 * .75) / (math.pi * (1.75 / 2.)**2)
ACCEL = 3000. * EXTRUDE_R
def gen_positions():
out = []
start_d = start_t = t = 0.
for start_v, end_v, move_t in Moves:
start_v *= EXTRUDE_R
end_v *= EXTRUDE_R
if move_t is None:
move_t = abs(end_v - start_v) / ACCEL
half_accel = 0.
if end_v > start_v:
half_accel = .5 * ACCEL
elif start_v > end_v:
half_accel = -.5 * ACCEL
end_t = start_t + move_t
while t <= end_t:
rel_t = t - start_t
out.append(start_d + (start_v + half_accel * rel_t) * rel_t)
t += SEG_TIME
start_d += (start_v + half_accel * move_t) * move_t
start_t = end_t
return out
def gen_deriv(data):
return [0.] + [(data[i+1] - data[i]) * INV_SEG_TIME
for i in range(len(data)-1)]
def time_to_index(t):
return int(t * INV_SEG_TIME + .5)
######################################################################
# Pressure advance
######################################################################
PA_HALF_SMOOTH_T = .040 / 2.
PRESSURE_ADVANCE = .045
def calc_pa_raw(t, positions):
pa = PRESSURE_ADVANCE * INV_SEG_TIME
i = time_to_index(t)
return positions[i] + pa * (positions[i+1] - positions[i])
def calc_pa_weighted(t, positions):
base_index = time_to_index(t)
start_index = time_to_index(t - PA_HALF_SMOOTH_T) + 1
end_index = time_to_index(t + PA_HALF_SMOOTH_T)
diff = .5 * (end_index - start_index)
pa = PRESSURE_ADVANCE * INV_SEG_TIME
pa_data = [(positions[i] + pa * (positions[i+1] - positions[i]))
* (diff - abs(i-base_index))
for i in range(start_index, end_index)]
return sum(pa_data) / diff**2
######################################################################
# Plotting and startup
######################################################################
MARGIN_TIME = 0.100
def plot_motion():
# Nominal motion
positions = gen_positions()
drop = int(MARGIN_TIME * INV_SEG_TIME)
times = [SEG_TIME * t for t in range(len(positions))][drop:-drop]
velocities = gen_deriv(positions[drop:-drop])
# Motion with pressure advance
pa_positions = [calc_pa_raw(t, positions) for t in times]
pa_velocities = gen_deriv(pa_positions)
# Smoothed motion
sm_positions = [calc_pa_weighted(t, positions) for t in times]
sm_velocities = gen_deriv(sm_positions)
# Build plot
shift_times = [t - MARGIN_TIME for t in times]
fig, ax1 = matplotlib.pyplot.subplots(nrows=1, sharex=True)
ax1.set_title("Extruder Velocity")
ax1.set_ylabel('Velocity (mm/s)')
pa_plot, = ax1.plot(shift_times, pa_velocities, 'r',
label='Pressure Advance', alpha=0.3)
nom_plot, = ax1.plot(shift_times, velocities, 'black', label='Nominal')
sm_plot, = ax1.plot(shift_times, sm_velocities, 'g', label='Smooth PA',
alpha=0.9)
fontP = matplotlib.font_manager.FontProperties()
fontP.set_size('x-small')
ax1.legend(handles=[nom_plot, pa_plot, sm_plot], loc='best', prop=fontP)
ax1.set_xlabel('Time (s)')
ax1.grid(True)
fig.tight_layout()
return fig
def setup_matplotlib(output_to_file):
global matplotlib
if output_to_file:
matplotlib.rcParams.update({'figure.autolayout': True})
matplotlib.use('Agg')
import matplotlib.pyplot, matplotlib.dates, matplotlib.font_manager
import matplotlib.ticker
def main():
# Parse command-line arguments
usage = "%prog [options]"
opts = optparse.OptionParser(usage)
opts.add_option("-o", "--output", type="string", dest="output",
default=None, help="filename of output graph")
options, args = opts.parse_args()
if len(args) != 0:
opts.error("Incorrect number of arguments")
# Draw graph
setup_matplotlib(options.output is not None)
fig = plot_motion()
# Show graph
if options.output is None:
matplotlib.pyplot.show()
else:
fig.set_size_inches(6, 2.5)
fig.savefig(options.output)
if __name__ == '__main__':
main()
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