- #1
leonpolou
- 1
- 0
Hi everyone,
here is the problem:
I am trying to reproduce a human finger while pressing a keyboard.
I am using a shaker and a fingertip made of foam rubber. To measure the force history, a force gage make a link between the fingertip and the shaker.
The fact is the curve has an offset and I try to know why.
A solution might be that we use the force gage at a 5.8Hz and that material is usully use with frequency upper than 10 Hz.
To solve that problem a basic solution would be to filter the signal recorded with an high pass filter.
Actually I really don't know how to do it.
here is my code on matlab
f=10; %Cut off frequency%
fs=42000; %resolution frequency%
w=f/(fs/2); % frequency normalized%
N=100; &filter order%
b=fir1(N,w,'high');
figure(1);
freqz(b,1,42000,fs); % we see how the filter look like%
y=fftfilt(b,X1(1:65536,2));
figure(2);
plot(X1(1:65536,1),y,'r',X1(1:65536,1),X1(1:65536,2))
First, how do you think is it possible to make a 10Hz high pass filter with matlab
Second, if you have some idea to solve my problem while using other thing than filter the signal, that would be a pleasure for me.
Regards
jeremy
here is the problem:
I am trying to reproduce a human finger while pressing a keyboard.
I am using a shaker and a fingertip made of foam rubber. To measure the force history, a force gage make a link between the fingertip and the shaker.
The fact is the curve has an offset and I try to know why.
A solution might be that we use the force gage at a 5.8Hz and that material is usully use with frequency upper than 10 Hz.
To solve that problem a basic solution would be to filter the signal recorded with an high pass filter.
Actually I really don't know how to do it.
here is my code on matlab
f=10; %Cut off frequency%
fs=42000; %resolution frequency%
w=f/(fs/2); % frequency normalized%
N=100; &filter order%
b=fir1(N,w,'high');
figure(1);
freqz(b,1,42000,fs); % we see how the filter look like%
y=fftfilt(b,X1(1:65536,2));
figure(2);
plot(X1(1:65536,1),y,'r',X1(1:65536,1),X1(1:65536,2))
First, how do you think is it possible to make a 10Hz high pass filter with matlab
Second, if you have some idea to solve my problem while using other thing than filter the signal, that would be a pleasure for me.
Regards
jeremy