Distance and velocity from acceleration plot

Hi,

I have some accelration data from an IMU and would like to get velocity and distance.

How could I do that?

Thanks in advance

figure
plot(dugyro,IMU_AccZ)
title('Acc Z - Raw Data')
ylabel("(m/sec/sec)")

Answer 1

[Walter Roberson]

You could use cumtrapz(), twice.

Caution: using numeric integration to calculate distance and velocity is rather prone to error.

https://en.wikipedia.org/wiki/Inertial_navigation_system

Even the best accelerometers, with a standard error of 10 micro-g, would accumulate a 50-meter error within 17 minutes

[Judah]

Thanks @Walter Roberson

I tried it but my values don't seem to make sense.

Yes I agree with you regarding the error therefore I took a small sample data but still both plots don't make sense to me.

%% Raw data
close all
figure
tiledlayout(3,1)
nexttile
New_IMU_AccZ = IMU_AccZ - mean(IMU_AccZ(:));
plot(dugyro,New_IMU_AccZ)
title('Acc Z - Raw Data')
ylabel("(m/sec/sec)")
Vel=cumtrapz(New_IMU_AccZ);
dist=cumtrapz(Vel)
nexttile
plot(dugyro,Vel)
title('Velocity')
ylabel("(m/sec)")
nexttile
plot(dugyro,dist)
title('Distance')
ylabel("(m)")
%% Sample data
sample= 1000:1500;
figure
tiledlayout(3,1)
nexttile
New_IMU_AccZ = IMU_AccZ - mean(IMU_AccZ(:));
plot(dugyro(sample,1),New_IMU_AccZ(sample,1))
title('Acc Z - Sample Data')
ylabel("(m/sec/sec)")
Vel=cumtrapz(New_IMU_AccZ(sample,1));
dist=cumtrapz(Vel)
nexttile
plot(dugyro(sample,1),Vel)
title('Velocity')
ylabel("(m/sec)")
nexttile
plot(dugyro(sample,1),dist)
title('Distance')
ylabel("(m)")

[Walter Roberson]

You should be passing the independent variable into cumtrapz

Vel = cumtrapz(dugyro, New_IMU_AccZ);
dist = cumtrapz(dugyro, Vel);

[Judah]

Then I get an error

Error using zeros
CLASSNAME argument must be a class that supports ZEROS, such as 'double' or 'single'.

Error in cumtrapz (line 81)
    z = [zeros(1,n,class(y)); cumsum(dt .* (y(1:end-1,:) + y(2:end,:)),1)];

Error in accel_data (line 11)
dist = cumtrapz(dugyro, Vel);

Related documentation
 

[Walter Roberson]

ds = seconds(dugyro);
Vel = cumtrapz(ds, New_IMU_AccZ);
dist = cumtrapz(ds, Vel);

[Judah]

Thank you @Walter Roberson