Programming Codes

// Encoder connect to digitalpin 2 and 3 on the Arduino.

volatile int counter = 0;  

//This variable will increase or decrease depending on the rotation of encoder

float angle, temp = 0.0 ;

float a=0.0;

void setup() {

  Serial.begin (9600);

  pinMode(2, INPUT);           // set pin to input

  pinMode(3, INPUT);           // set pin to input

  digitalWrite(2, HIGH);       // turn on pullup resistors

  digitalWrite(3, HIGH);       // turn on pullup resistors

  //Setting up interrupt

  //A rising pulse from encodenren activated ai0(). AttachInterrupt 0 is DigitalPin nr 2 on moust Arduino.

  attachInterrupt(0, ai0, RISING);

  //B rising pulse from encodenren activated ai1(). AttachInterrupt 1 is DigitalPin nr 3 on moust Arduino.

  attachInterrupt(1, ai1, RISING);

}

void loop() {

  // Send the value of counter

  if(counter >= 1200 || counter <= -1200) counter = 0;

  angle = counter*(3.00/10.00) ;

  if(angle != temp){

    temp = angle;

    a = millis();

    //Serial.print (",");

    Serial.print (a);

    Serial.print (",");

    Serial.println (angle);

    //Serial.println (counter);

  }

}

void ai0() {

  // ai0 is activated if DigitalPin nr 2 is going from LOW to HIGH

  // Check pin 3 to determine the direction

  if(digitalRead(3)==LOW) {

    counter++;

  }else{

    counter--;

  }

}

void ai1() {

  // ai0 is activated if DigitalPin nr 3 is going from LOW to HIGH

  // Check with pin 2 to determine the direction

  if(digitalRead(2)==LOW) {

    counter--;

  }else{

    counter++;

  }

}

import numpy as np

from scipy.fftpack import fft,ifft

import matplotlib.pyplot as plt

import scipy as sp

from ipywidgets import interact

from scipy.integrate import odeint

%matplotlib inline

time = []

data = []

#hex1mm_8_2.csv為數據檔，請改成要匯入的檔名

with open('hex1mm_8_2.csv','r',encoding='utf-8-sig') as f:

    s = f.read()

    b = s.split()

    for i in b:

        c=i.split(',')

        time.append(c[0])

        data.append(c[1])

    print(len(time))

    print(len(data))

time = np.array(time, dtype="float")/1000-int(time[0])/1000

data = np.array(data, dtype="float")

plt.plot(time,data)

plt.show()

total_time = max(time)-min(time)

sampling_rate = int(len(time)/total_time) #sampling_rate為 1/時間間隔

fft_size = len(time)      #fft_size為總共數據數量

t = np.array(time, dtype="float")

x = np.array(data, dtype="float")

xs = x[:fft_size]

xf = np.fft.rfft(xs) / fft_size

xss = len(x) 

ts = t[:xss]

x = np.array(x, dtype="float")

ts = np.array(ts, dtype="float")

plt.plot(ts,x)

plt.show()

freqs = np.linspace(0, sampling_rate/2, int(fft_size/2+1))  

xfp = 20*np.log10(np.clip(np.abs(xf), 1e-2, 1e2))

freqs = np.array(freqs, dtype="float")

xfp = np.array(xfp, dtype="float")

freqs = freqs[1:]

xfp = xfp[1:]

plt.plot(freqs,xfp)

plt.show()

num = xfp.argmax(axis=0)

print("頻率:",freqs[num]) #頻率

print("週期:",1/freqs[num]) #週期

import numpy as np

from scipy.fftpack import fft,ifft

import matplotlib.pyplot as plt

import scipy as sp

from ipywidgets import interact

from scipy.integrate import odeint

%matplotlib inline

time = []

data = []

#hex1mm_8_2.csv為數據檔，請改成要匯入的檔名

with open('hex1mm_8_2.csv','r',encoding='utf-8-sig') as f:

    s = f.read()

    b = s.split()

    for i in b:

        c=i.split(',')

        time.append(c[0])

        data.append(c[1])

    print(len(time))

    print(len(data))

time = np.array(time, dtype="float")/1000-int(time[0])/1000

data = np.array(data, dtype="float")

plt.plot(time,data)

plt.show()

dx = []

dc = []

dt = []

dxx = []

dcc = []

for i in range(0,len(time)-1):

    p = (data[i+1]+data[i])/2

    t = (time[i+1]-time[i])

    dc.append(p) #一次微分的角位置

    dt.append(t) #時間差

for k in range(0,len(dc)):

    xx = (data[k+1]-data[k])/dt[k] 

    dx.append(xx) #一次微分

for j in range(0,len(dx)-1):

    pp = (dc[j+1]+dc[j])/2 

    dcc.append(pp) #二次微分的角位置

for m in range(0,len(dx)-1):

    xxx = (dx[m+1]-dx[m])/dt[m]

    dxx.append(xxx) #二次微分

plt.plot(dcc[10:],dxx[10:],"o")

np.polyfit(dcc,dxx,1)

x2 = np.arange(min(dcc),max(dcc),0.1)

y2 = np.polyfit(dcc[10:],dxx[10:],1)[0]*x2+np.polyfit(dcc[10:],dxx[10:],1)[1]

plt.plot(x2,y2)

plt.show()

print('y = %.2f x'%np.polyfit(dcc,dxx,1)[0],'+ %.2f'%np.polyfit(dcc,dxx,1)[1])

import numpy as np

from scipy.fftpack import fft,ifft

import matplotlib.pyplot as plt

import scipy as sp

from ipywidgets import interact

from scipy.integrate import odeint

%matplotlib inline

time = []

data = []

#tt1.csv為數據檔，請改成要匯入的檔名

with open('hex1mm_8_2.csv','r',encoding='utf-8-sig') as f:

    s = f.read()

    b = s.split()

    for i in b:

        c=i.split(',')

        time.append(c[0])

        data.append(c[1])

    print(len(time))

    print(len(data))

time = np.array(time, dtype="float")/1000-int(time[0])/1000

data = np.array(data, dtype="float")

plt.plot(time,data)

plt.show()

def decay(a,x,t,y0):

    y = a*np.exp(-x/t)+y0

    return y

#a(震幅), t(半衰期), y0(截距), T(時間)

def plot_osc(a,  t = 0.81, y0= 2.36, T = 5):

    N_data = np.arange(0,T,0.001)

    #plt.title('Ultrasonic oscillations\nh=%2.2f, b=%2.2f, a=%2.2f, m=%2.2f, g=%2.2f, f=%2.2f\nfilename = %s'%(h,b,a,m,g,f,filename),fontsize=15)

    #x0 = [h, 0.0]

    plt.plot(time,data,'.')

    plt.xlabel('time (sec)',fontsize=15)

    plt.ylabel('amp (cm)',fontsize=15)

    plt.plot(N_data, decay(a,N_data,t,y0), 'b', label='y(t)')

    plt.legend(loc='best')

    plt.xlabel('T')

    plt.grid()

    plt.show()

interact(plot_osc, a = (0.0, 360.0,0.01), t = (0,2,0.01), y0 = (0.00,10,0.01), T = (0.0, 8, 0.1));