Double Integration : (Displacement signals from the Acceleration data)

Hi,

In order to obtain the displacement signals from the acceleration data, The following steps are used to convert the acceleration data to achieve the displacement values:

1- The acceleration signals are filtered [High pass filter]

2- The cumtrapz is applied to integrate the displacement to obtain the velocity

3- The velocity signals are filtered [High pass filter]

4- Finally, the filtered signals of velocity is integrated to get the displacement signals.

The concern is still about the correct methods and the accuracy of the results which are obtained. Please have look at the Matlab Program as stated below; If there any comments and contribution regarding the proposed methodology please do not hesitate to shear us your experience, Thank you

%% accelerations are integrated twice to produce displacements

clear all

close all

clc

time = load('D:\Users\Desktop\time.txt');

acc = load('D:\Users\Desktop\data.txt');

figure

plot(time,acc)

xlabel('Time (sec)')

ylabel('Acceleration (mm/sec^2)')

%% Design High Pass Filter

fs = 8000; % Sampling Rate

fc = 0.1/30; % Cut off Frequency

order = 6; % 6th Order Filter

%% Filter Acceleration Signals

[b1 a1] = butter(order,fc,'high');

accf=filtfilt(b1,a1,acc);

figure (2)

plot(time,accf,'r'); hold on

plot(time,acc)

xlabel('Time (sec)')

ylabel('Acceleration (mm/sec^2)')

%% First Integration (Acceleration - Veloicty)

velocity=cumtrapz(time,accf);

figure (3)

plot(time,velocity)

xlabel('Time (sec)')

ylabel('Velocity (mm/sec)')

%% Filter Veloicty Signals

[b2 a2] = butter(order,fc,'high');

velf = filtfilt(b2,a2,velocity);

%% Second Integration (Velocity - Displacement)

Displacement=cumtrapz(time, velf);

figure(4)

plot(time,Displacement)

xlabel('Time (sec)')

ylabel('Displacement (mm)')

Answer 1

[Torsten]

http://www.mathworks.com/matlabcentral/answers/17611-how-to-convert-a-accelerometer-data-to-displacements

Best wishes

Torsten.

[Dr. Seis]

Better code here: http://www.mathworks.com/matlabcentral/answers/21700-finding-the-velocity-from-displacement