combine tools into one
This commit is contained in:
Andrew de Quincey
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@ -21,7 +21,7 @@ There needs to be no abnormal source of temperature change to the kiln: eg if yo
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To record the profile, run:
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```
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python kiln-tuner.py zn.csv
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python kiln-tuner.py recordprofile zn.csv
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```
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The above will drive your kiln to 400 and record the temperature profile to the file `zn.csv`. The file will look something like this:
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@ -40,7 +40,7 @@ time,temperature
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Once you have your zn.csv profile, run the following:
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```
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python zieglernicols.py zn.csv
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python kiln-tuner.py zn zn.csv
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```
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The values will be output to stdout, for example:
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@ -55,7 +55,7 @@ Kp: 3.853985144980333 1/Ki: 87.78173053095107 Kd: 325.9599328488931
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If you run
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```
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python zieglernicols.py zn.csv --showplot
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python kiln-tuner.py zn zn.csv --showplot
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```
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It will display a plot of the parameters. It should look simular to this .
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@ -71,7 +71,7 @@ The red diagonal line: this **must** follow the smooth part of your chart closel
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You might need to adjust the line parameters to make it fit your data properly. You can do this as follows:
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```
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python zieglernicols.py zn.csv --tangentdivisor 8
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python kiln-tuner.py zn zn.csv --tangentdivisor 8
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```
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`tangentdivisor` modifies which parts of the profile is used to calculate the line.
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@ -83,7 +83,7 @@ It is a floating point number >= 2; If necessary, try varying it till you get a
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By default it is 400. You can change this as follows:
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```
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python kiln-tuner.py zn.csv --targettemp 500
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python kiln-tuner.py recordprofile zn.csv --targettemp 500
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```
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(where the target temperature has been changed to 500)
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(where the target temperature has been changed to 500 in the example above)
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147
kiln-tuner.py
147
kiln-tuner.py
@ -7,24 +7,24 @@ import time
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import argparse
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try:
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sys.dont_write_bytecode = True
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import config
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sys.dont_write_bytecode = False
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def recordprofile(csvfile, targettemp):
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except:
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print("Could not import config file.")
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print("Copy config.py.EXAMPLE to config.py and adapt it for your setup.")
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exit(1)
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try:
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sys.dont_write_bytecode = True
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import config
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sys.dont_write_bytecode = False
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script_dir = os.path.dirname(os.path.realpath(__file__))
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sys.path.insert(0, script_dir + '/lib/')
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profile_path = os.path.join(script_dir, "storage", "profiles")
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except:
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print("Could not import config file.")
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print("Copy config.py.EXAMPLE to config.py and adapt it for your setup.")
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exit(1)
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from oven import RealOven, SimulatedOven
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script_dir = os.path.dirname(os.path.realpath(__file__))
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sys.path.insert(0, script_dir + '/lib/')
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profile_path = os.path.join(script_dir, "storage", "profiles")
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from oven import RealOven, SimulatedOven
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def tune(csvfile, targettemp):
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# open the file to log data to
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f = open(csvfile, 'w')
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csvout = csv.writer(f)
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@ -78,10 +78,125 @@ def tune(csvfile, targettemp):
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oven.output.heat(0)
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def line(a, b, x):
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return a * x + b
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def invline(a, b, y):
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return (y - b) / a
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def plot(xdata, ydata,
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tangent_min, tangent_max, tangent_slope, tangent_offset,
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lower_crossing_x, upper_crossing_x):
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from matplotlib import pyplot
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minx = min(xdata)
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maxx = max(xdata)
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miny = min(ydata)
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maxy = max(ydata)
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pyplot.scatter(xdata, ydata)
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pyplot.plot([minx, maxx], [miny, miny], '--', color='purple')
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pyplot.plot([minx, maxx], [maxy, maxy], '--', color='purple')
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pyplot.plot(tangent_min[0], tangent_min[1], 'v', color='red')
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pyplot.plot(tangent_max[0], tangent_max[1], 'v', color='red')
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pyplot.plot([minx, maxx], [line(tangent_slope, tangent_offset, minx), line(tangent_slope, tangent_offset, maxx)], '--', color='red')
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pyplot.plot([lower_crossing_x, lower_crossing_x], [miny, maxy], '--', color='black')
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pyplot.plot([upper_crossing_x, upper_crossing_x], [miny, maxy], '--', color='black')
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pyplot.show()
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def calculate(filename, tangentdivisor, showplot):
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# parse the csv file
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xdata = []
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ydata = []
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filemintime = None
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with open(filename) as f:
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for row in csv.DictReader(f):
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try:
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time = float(row['time'])
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temp = float(row['temperature'])
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if filemintime is None:
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filemintime = time
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xdata.append(time - filemintime)
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ydata.append(temp)
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except ValueError:
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continue # just ignore bad values!
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# gather points for tangent line
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miny = min(ydata)
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maxy = max(ydata)
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midy = (maxy + miny) / 2
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yoffset = int((maxy - miny) / tangentdivisor)
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tangent_min = tangent_max = None
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for i in range(0, len(xdata)):
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rowx = xdata[i]
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rowy = ydata[i]
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if rowy >= (midy - yoffset) and tangent_min is None:
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tangent_min = (rowx, rowy)
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elif rowy >= (midy + yoffset) and tangent_max is None:
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tangent_max = (rowx, rowy)
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# calculate tangent line to the main temperature curve
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tangent_slope = (tangent_max[1] - tangent_min[1]) / (tangent_max[0] - tangent_min[0])
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tangent_offset = tangent_min[1] - line(tangent_slope, 0, tangent_min[0])
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# determine the point at which the tangent line crosses the min/max temperaturess
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lower_crossing_x = invline(tangent_slope, tangent_offset, miny)
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upper_crossing_x = invline(tangent_slope, tangent_offset, maxy)
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# compute parameters
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L = lower_crossing_x - min(xdata)
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T = upper_crossing_x - lower_crossing_x
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# Magic Ziegler-Nicols constants ahead!
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Kp = 1.2 * (T / L)
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Ti = 2 * L
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Td = 0.5 * L
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Ki = Kp / Ti
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Kd = Kp * Td
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# outut to the user
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print(f"Kp: {Kp} 1/Ki: {1/ Ki}, Kd: {Kd}")
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if showplot:
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plot(xdata, ydata,
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tangent_min, tangent_max, tangent_slope, tangent_offset,
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lower_crossing_x, upper_crossing_x)
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if __name__ == "__main__":
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parser = argparse.ArgumentParser(description='Record data for kiln tuning')
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parser.add_argument('csvfile', type=str, help="The CSV file to write to.")
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parser.add_argument('--targettemp', type=int, default=400, help="The target temperature to drive the kiln to (default 400).")
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subparsers = parser.add_subparsers()
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parser_profile = subparsers.add_parser('recordprofile', help='Record kiln temperature profile')
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parser_profile.add_argument('csvfile', type=str, help="The CSV file to write to.")
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parser_profile.add_argument('--targettemp', type=int, default=400, help="The target temperature to drive the kiln to (default 400).")
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parser_profile.set_defaults(mode='recordprofile')
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parser_zn = subparsers.add_parser('zn', help='Calculate Ziegler-Nicols parameters')
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parser_zn.add_argument('csvfile', type=str, help="The CSV file to read from. Must contain two columns called pid_time (time in seconds) and pid_ispoint (observed temperature)")
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parser_zn.add_argument('--showplot', action='store_true', help="If set, also plot results (requires pyplot to be pip installed)")
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parser_zn.add_argument('--tangentdivisor', type=float, default=4, help="Adjust the tangent calculation to fit better. Must be >= 2.")
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parser_zn.set_defaults(mode='zn')
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args = parser.parse_args()
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tune(args.csvfile, args.targettemp)
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if args.mode == 'recordprofile':
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recordprofile(args.csvfile, args.targettemp)
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elif args.mode == 'zn':
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if args.tangentdivisor < 2:
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raise ValueError("tangentdivisor must be >= 2")
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calculate(args.csvfile, args.tangentdivisor, args.showplot)
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else:
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raise NotImplementedError(f"Unknown mode {args.mode}")
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115
zieglernicols.py
115
zieglernicols.py
@ -1,115 +0,0 @@
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#!/usr/bin/env python
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import csv
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import argparse
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# Using the method described in "Ziegler–Nichols Tuning Method∗" by Vishakha Vijay Patel
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# (https://www.ias.ac.in/article/fulltext/reso/025/10/1385-1397)
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def line(a, b, x):
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return a * x + b
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def invline(a, b, y):
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return (y - b) / a
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def plot(xdata, ydata,
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tangent_min, tangent_max, tangent_slope, tangent_offset,
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lower_crossing_x, upper_crossing_x):
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from matplotlib import pyplot
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minx = min(xdata)
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maxx = max(xdata)
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miny = min(ydata)
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maxy = max(ydata)
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pyplot.scatter(xdata, ydata)
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pyplot.plot([minx, maxx], [miny, miny], '--', color='purple')
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pyplot.plot([minx, maxx], [maxy, maxy], '--', color='purple')
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pyplot.plot(tangent_min[0], tangent_min[1], 'v', color='red')
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pyplot.plot(tangent_max[0], tangent_max[1], 'v', color='red')
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pyplot.plot([minx, maxx], [line(tangent_slope, tangent_offset, minx), line(tangent_slope, tangent_offset, maxx)], '--', color='red')
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pyplot.plot([lower_crossing_x, lower_crossing_x], [miny, maxy], '--', color='black')
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pyplot.plot([upper_crossing_x, upper_crossing_x], [miny, maxy], '--', color='black')
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pyplot.show()
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def calculate(filename, tangentdivisor, showplot):
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# parse the csv file
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xdata = []
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ydata = []
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filemintime = None
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with open(filename) as f:
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for row in csv.DictReader(f):
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try:
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time = float(row['time'])
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temp = float(row['temperature'])
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if filemintime is None:
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filemintime = time
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xdata.append(time - filemintime)
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ydata.append(temp)
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except ValueError:
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continue # just ignore bad values!
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# gather points for tangent line
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miny = min(ydata)
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maxy = max(ydata)
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midy = (maxy + miny) / 2
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yoffset = int((maxy - miny) / tangentdivisor)
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tangent_min = tangent_max = None
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for i in range(0, len(xdata)):
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rowx = xdata[i]
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rowy = ydata[i]
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if rowy >= (midy - yoffset) and tangent_min is None:
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tangent_min = (rowx, rowy)
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elif rowy >= (midy + yoffset) and tangent_max is None:
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tangent_max = (rowx, rowy)
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# calculate tangent line to the main temperature curve
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tangent_slope = (tangent_max[1] - tangent_min[1]) / (tangent_max[0] - tangent_min[0])
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tangent_offset = tangent_min[1] - line(tangent_slope, 0, tangent_min[0])
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# determine the point at which the tangent line crosses the min/max temperaturess
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lower_crossing_x = invline(tangent_slope, tangent_offset, miny)
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upper_crossing_x = invline(tangent_slope, tangent_offset, maxy)
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# compute parameters
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L = lower_crossing_x - min(xdata)
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T = upper_crossing_x - lower_crossing_x
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# Magic Ziegler-Nicols constants ahead!
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Kp = 1.2 * (T / L)
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Ti = 2 * L
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Td = 0.5 * L
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Ki = Kp / Ti
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Kd = Kp * Td
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# outut to the user
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print(f"Kp: {Kp} 1/Ki: {1/ Ki}, Kd: {Kd}")
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if showplot:
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plot(xdata, ydata,
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tangent_min, tangent_max, tangent_slope, tangent_offset,
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lower_crossing_x, upper_crossing_x)
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if __name__ == "__main__":
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parser = argparse.ArgumentParser(description='Perform Ziegler-Nichols PID tuning')
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parser.add_argument('csvfile', type=str, help="The CSV file to read from. Must contain two columns called pid_time (time in seconds) and pid_ispoint (observed temperature)")
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parser.add_argument('--showplot', action='store_true', help="If set, also plot results (requires pyplot to be pip installed)")
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parser.add_argument('--tangentdivisor', type=float, default=4, help="Adjust the tangent calculation to fit better. Must be >= 2.")
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args = parser.parse_args()
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if args.tangentdivisor < 2:
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raise ValueError("tangentdivisor must be >= 2")
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calculate(args.csvfile, args.tangentdivisor, args.showplot)
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