bmarechal / py-ident

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Commit 8fe481d7425fb86b830c3abc34259e55d617c992

Authored by mer0m
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Update first_order_ident.py

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first_order_ident.py
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# -*- coding: utf-8 -*- 1 1 # -*- coding: utf-8 -*-
""" 2
Created on Fri Mar 11 11:04:35 2016 3
4
@author: Baptiste Marechal 5
""" 6
7 2
from scipy import signal, linspace, pi, randn, ones 8 3 from scipy import signal, linspace, pi, randn, ones
from scipy.optimize import curve_fit 9 4 from scipy.optimize import curve_fit
import matplotlib.pyplot as plt 10 5 import matplotlib.pyplot as plt
import time 11 6 import time
12 7
tic = time.time() 13 8 tic = time.time()
14 9
'''function to optimize''' 15 10 '''function to optimize'''
def func(u, K, tau, y0): 16 11 def func(u, K, tau, y0):
sys = signal.lti(K, [tau, 1]) 17 12 sys = signal.lti(K, [tau, 1])
y = sys.output(u, t, y0) 18 13 y = sys.output(u, t, y0)
return y[1] 19 14 return y[1]
20 15
'''input square signal''' 21 16 '''input square signal'''
global t 22 17 global t
t = linspace(0, 20, 1000) 23 18 t = linspace(0, 20, 1000)
Umes = -0.5*(signal.square(2*pi*0.1*t)+ones(len(t)))+ones(len(t))+randn(len(t))/50 24 19 Umes = -0.5*(signal.square(2*pi*0.1*t)+ones(len(t)))+ones(len(t))+randn(len(t))/50
25 20
'''noisy output signal''' 26 21 '''noisy output signal'''
p = [1, 1, 0] 27 22 p = [1, 1, 0]
Ymes = func(Umes, *p)+randn(len(Umes))/50 28 23 Ymes = func(Umes, *p)+randn(len(Umes))/50
29 24
'''input and output signals plot''' 30 25 '''input and output signals plot'''
plt.plot(t, Umes, label = 'Umes') 31 26 plt.plot(t, Umes, label = 'Umes')
plt.plot(t, Ymes, label = 'Ymes') 32 27 plt.plot(t, Ymes, label = 'Ymes')
33 28
34 29
'''optimization with non-linear least squares method''' 35 30 '''optimization with non-linear least squares method'''
popt, cov = curve_fit(func, Umes, Ymes) 36 31 popt, cov = curve_fit(func, Umes, Ymes)
print(p) 37 32 print(p)