MPU-6050 accelerometer reading of one direction

Hi!

I am using these line of code to continuously read the real-time acceleration values from the IMU(MPU-6050):

clear;
a = arduino('COM5','Uno','Libraries',{'I2C','SPI'});
imu = mpu6050(a,'SampleRate',50,'SamplesPerRead',5,'ReadMode','Latest');
accelReadings = readAcceleration(imu);
display(accelReadings);
    

It will returns one sample of the acceleration data on x, y, and z axes read from the sensor in units of m/s2 like this:

accelReadings =

   -2.3399   -0.5377    3.0201

Is there any possible way for me to retrive only the value of the x axis (the first value only)? I tried to treat it as an array but it is not working.

Also, can I fuse the data (estimate the orientation, quaternion, determine roll, pitch and yaw angles) of this type of this 6DOF sensor(MPU6050) as there is no magnetometer?

Thanks!

Answer 1

[Gayatri Menon]

Hi

accelReadings(1) should give you the x values. If you have a license for Sensor Fusion and Tracking toolbox or Navigation toolbox, try using read() for more capabilities. For usage and examples, please refer link for read() .

If you have the above-mentioned licenses, you can use imufilter to determine orientation.'imufilter' uses only accelerometer and gyroscope values. Refer to the example here.

Hope this helps

Thanks

Gayatri

[Nguyen Trieu]

Thank you for your response, however I am only interested in retrieving the values appeares on the axes seperately to plot the graph of the accelerometer values on x, y and z axes. The read fuction always generate the result as a set of 3x1 matrix.

And regarding the gyro and accel value fusion, I can't figure out how to get the value of accelerometor noise of 0.0061m/s^2 in this piece of code in the example:

displayMessage(['This section uses  IMU filter to determine orientation of the sensor by collecting live sensor data from the \slmpu9250 \rm' ...
    'system object. Move the sensor to visualize orientation of the sensor in the figure window. Keep the sensor stationery before you'...
    'click OK'],...
    'Estimate Orientation using IMU filter and MPU-9250.')
% GyroscopeNoise and AccelerometerNoise is determined from datasheet.
GyroscopeNoiseMPU9250 = 3.0462e-06; % GyroscopeNoise (variance) in units of rad/s
AccelerometerNoiseMPU9250 = 0.0061; % AccelerometerNoise (variance) in units of m/s^2
viewer = HelperOrientationViewer('Title',{'IMU Filter'});
FUSE = imufilter('SampleRate',imu.SampleRate, 'GyroscopeNoise',GyroscopeNoiseMPU9250,'AccelerometerNoise', AccelerometerNoiseMPU9250);
stopTimer=100;

Would you mind clarify?

Best Regards.

[Gayatri Menon]

Please refer the below link.This link explains how the noise is calculated for MPU9250. A similar approach can be used for mpu6050 as well

https://www.mathworks.com/matlabcentral/answers/479168-how-is-accelerometer-and-gyroscope-noise-calculated-from-datasheet-of-mpu9250-in-the-below-example

Thanks

Gayatri