Computing displacement from accelerometer data

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Paul Heineman 2022-9-27

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1813265-computing-displacement-from-accelerometer-data

评论： Cris LaPierre 2022-9-27

采纳的回答： Cris LaPierre

Acceleration without g 2022-09-07 09-49-36.xls

在 MATLAB Online 中打开

Hi,

I am trying to convert my accelerometer data to displacement data through integrating twice, I looked at other questions here and similar questions have been asked and answered however I still dont get a satisfactory answer.

Te problem I have is that I get a displacement of 5*10^-3 which does not make sense from the experiment. I have attached my data for reference.

I import the data from excel, detrend it and then use the function cumtrapz twice.

data = readmatrix('https://de.mathworks.com/matlabcentral/answers/uploaded_files/1138190/Acceleration%20without%20g%202022-09-07%2009-49-36.xls');

%Acceleration data

acc = data(:,4); % Add gravity factor ( g to m/sÂ²)

%acc = flip(acc);

acc = detrend(acc); % baseline correction

%Time

tStep = 20/length(acc);

N = length(acc)*tStep;

t = 0:tStep:N;

t(end) = [];

N = length(t);

dt = mean(diff(t));

fs = 1/dt;

% High pass filter

N = 2;

fc = 2;

[B,A] = butter(N,2*fc/fs,'high');

acc2 = filter(B,A,acc);

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

velocity = cumtrapz(dt,acc2);

velocity = detrend(velocity); % baseline correction

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

disp = cumtrapz(dt,velocity);

%disp = detrend(disp); % baseline correction

%

figure(1)

%plot(t,acc);

hold on;

%plot(t,velocity);

hold on;

plot(t,disp);

title('disp'); ylabel('m');xlabel('time (s)');

I am wondering what I do wrong, thanks in advance

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Answer 1

Cris LaPierre 2022-9-27

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1813265-computing-displacement-from-accelerometer-data#answer_1061900

编辑：Cris LaPierre 2022-9-27

在 MATLAB Online 中打开

I think the first issue is to find the magnitude of the acceleration vector using the data from all 3 axes. From there, you can use cumtrapz with the Time and acceleration data, then Time and the resulting velocity to get position.

file = "https://www.mathworks.com/matlabcentral/answers/uploaded_files/1138190/Acceleration%20without%20g%202022-09-07%2009-49-36.xls";

data = readtable(file);

Warning: Column headers from the file were modified to make them valid MATLAB identifiers before creating variable names for the table. The original column headers are saved in the VariableDescriptions property.
Set 'VariableNamingRule' to 'preserve' to use the original column headers as table variable names.

data.Properties.VariableNames = ["Time","X","Y","Z","Abs"];

% Combined acceleration

accel = sqrt(data.X.^2 + data.Y.^2 + data.Z.^2);

figure

plot(data.Time,accel)

v = cumtrapz(data.Time,accel);

x = cumtrapz(data.Time,v);

figure

plot(data.Time,v)

figure

plot(data.Time,x)

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Paul Heineman 2022-9-27

编辑：Paul Heineman 2022-9-27

Thank you for your quick answer chris, however I think I should have been more carefull stating my question. The experiment was a cantilever beam oscilating in the z direction, and the displacement should be around the x axis in the graph. The result would mean that all three graphs look similar, I expect a displacement between 1 and 10 centimeter in positive and negative direction (z -axis from the data).

Cris LaPierre 2022-9-27

We would need to know the initial conditions. Perhaps most relevant here would be what the initial displacement of the cantilever beam was, as your data starts with max acceleration in Z

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Computing displacement from accelerometer data

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