Power spectral density unit conversion

Hello,

Is there a quick way to convert the Noise Power Spectral Density of the accelerometer from 300µg/√Hz to m/s^2 as an acceleration unit?

Thanks.

Answer 1

[Devineni Aslesha]

To convert the Noise Power Spectral Density of the accelerometer as an acceleration unit, see the code below.

psd = 300*1e-6;
w = 2*pi*f;    % f is in Hz
psdToAcc = psd*sqrt(w);    % Converting psd to acceleration unit 'g'
gTomps2 = convacc(psdToAcc,'G''s','m/s^2');

For more information, refer the following link.

https://www.mathworks.com/help/aerotbx/ug/convacc.html

[Nguyen Trieu]

I am trying to examinate how the fusion function works with the example "Estimating Orientation Using Inertial Sensor Fusion and MPU-9250" and not be able to figure out this one part of the code where the noise of the acceleration is assigned to the value of: 0.0061m/s^2.

% GyroscopeNoise and AccelerometerNoise is determined from datasheet.
GyroscopeNoiseMPU9250 = 3.0462e-06; % GyroscopeNoise (variance value) in units of rad/s
AccelerometerNoiseMPU9250 = 0.0061; % AccelerometerNoise(variance value)in units of m/s^2
viewer = HelperOrientationViewer('Title',{'AHRS Filter'});
FUSE = ahrsfilter('SampleRate',imu.SampleRate, 'GyroscopeNoise',GyroscopeNoiseMPU9250,'AccelerometerNoise',AccelerometerNoiseMPU9250);
stopTimer 

I have tried to look through the datasheet of MPU-9250 and wondering wheter or not the Noise Power Spectral Density with the value of 300µg/√Hz to be converted into the 0.0061m/s^2 above? I have tried to work with 300µg/√Hz with the code you have suggested but it doesn't return the value of 0.0061m/s^2 as above.

https://au.mathworks.com/help/fusion/examples/Estimating-Orientation-Using-Inertial-Sensor-Fusion-and-MPU-9250.html#EstimateOrientationUsingInertialSensorFusionAndMPU9250Example-6

[Nguyen Trieu]

The script I used is:

psd = 300*1e-6;
w = 2*pi*10;    % f is in Hz(I believe it is 10 Hz according to the MPU-9250 datasheet).
psdToAcc = psd*sqrt(w);    % Converting psd to acceleration unit 'g'
gTomps2 = convacc(psdToAcc,'G''s','m/s^2');