Converting tremor data in to frequency and filter data
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Can anyone help in apply fft and filtering to my IMU sensor data for detecting tremor
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Star Strider
2022 年 9 月 13 日
編集済み: Star Strider
2022 年 9 月 14 日
The fft plots are straightforward, however only the acceleration signals make sense. The ‘Gyr’ signals exhibit broadband noise.
How do you want to process them?
One approach —
T1 = readtable('https://www.mathworks.com/matlabcentral/answers/uploaded_files/1124040/labeled%20final%20data.csv')
Acc = T1{:,1:3}
Gyr = T1{:,4:6};
Data = [Acc Gyr];
Fs = 1; % Sampling Frequency
Fn = Fs/2; % Nyquist Frequency
NrSp = size(Data,2); % Number Of Subplots
L = size(Data,1); % Length Of Data Vectors
t = linspace(0, L-1, L)/Fs; % Time Vector
NFFT = 2^nextpow2(L); % For Efficiency
FTData = fft(Data - mean(Data),NFFT)/L; % Fopurier Transform
Fv = linspace(0, 1, NFFT/2-1)*Fn; % Frequency Vector (For Plots)
Iv = 1:numel(Fv); % Index Vector (For Plots)
figure
sp = [1:2:NrSp 2:2:NrSp]; % Order 'subplot' Plots
for k = 1:NrSp
subplot(3,2,sp(k))
plot(Fv, abs(FTData(Iv,k))*2) % Plot Fourier Transforms
grid
xlabel('Frequency')
ylabel('Magnitude')
xlim([0 Fn/20])
% xlim([5 10])
title(sprintf('Column %d',k))
end
sgtitle('Fourier Transform of Data')
figure
sp = [1:2:NrSp 2:2:NrSp];
for k = 1:NrSp
subplot(3,2,sp(k))
plot(t, Data(:,k))
grid
ylim([-3 3])
xlabel('Time')
ylabel('Amplitude')
title(sprintf('Column %d',k))
end
sgtitle('Original Time-Domain Data')
Wp = [0.0001 0.005]/Fn; % Define Passband In Hz, Normalise To (0,pi)
Ws = Wp.*[0.95 1.05]; % Stopband (Normalised)
Rs = 50; % Stopband Ripple (Attenuation) dB
Rp = 1; % Passband Ripple dB
[n,Wn] = ellipord(Wp,Ws,Rp,Rs); % Calculate Filter Order
[z,p,k] = ellip(n,Rp,Rs,Wp); % Design Filter
[sos,g] = zp2sos(z,p,k); % Implement Filter As Second-Order-Section Representation
figure
freqz(sos, 2^16, Fs) % Filter Bode Plot
set(subplot(2,1,1), 'XLim',[0 0.01])
set(subplot(2,1,2), 'XLim',[0 0.01])
Data_Filt = filtfilt(sos,g,Data);
figure
for k = 1:NrSp
subplot(3,2,sp(k))
plot(t, Data_Filt(:,k))
grid
ylim([-1 1]*0.75)
xlabel('Time')
ylabel('Amplitude')
title(sprintf('Column %d',k))
end
sgtitle('Time-Domain Plots of Bandpass (0.0001 - 0.005 Hz) Filtered Data')
EDIT — (14 Sep 2022 at 11:40)
Changed ‘Fs’ and filter passbands to conform to the 1 Hz sampling frequency.
.
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