Remove gravity component from accelerometer data

Hi all,

could you advice me a method to remove the gravity component from my 3-axis accelerometer data?

Thank a lot for your help and time, much appreciated!

I've shared also my x y and z. thanks a lot!!

Answer 1

[Mathieu NOE]

hello Francesco

the simplest method is to simply remove the mean value of your signal.

another approach is to use a high pass filter, this can also be useful if you want to remove very low frequency drifts or motion effects .

tested on you x data , you can easily copy paste on y and z data;

plot :

code :

clc
clearvars
load('x.mat');
% load('y.mat');
% load('z.mat');

% Time
dt = 1e-3;      % Length of each time step
samples = length(x);
t_ac = (0:samples-1)'*dt;
fs = 1/dt;                  % Frequency [Hz] or sampling rate

% acc = x(:)*9.81;  % Add gravity factor (assumes data in g)
acc = x(:);         % No gravity factor (assumes data in m/s²)

% remove "gravity" acceleration 
% method 1 : remove mean value
acc_ref = mean(acc);
acc2 = acc - acc_ref;   %  ??

% method 2 : high pass filtering
N = 2;
fc = 1; % Hz
[B,A] = butter(N,2*fc/fs,'high');
acc3 = filter(B,A,acc);

figure(1)
plot(t_ac,acc,t_ac,acc2,t_ac,acc3);
title('acceleration (unit ?)');
xlabel('Time (s)')
ylabel('Amplitude (unit ?)')
legend('raw','mean removed','high pass filtered');

[Francesco Lucarelli]

Thank a lot @Mathieu NOE

Much appriciated !!

[Mathieu NOE]

you're welcome !