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Hello

I've just subscribe because I've a problem with a project.

First, I'm a student in France, in prep school. My team and I are working on a project : we study the perfect path for an airplane to be in micro-gravity (it means the only acceleration is the one due to gravity, like what we have here :http://www.airzerog.com/)

So, in order to verify our theoretical model, we experienced in an aerobatic plane (CAP10) and we had a accelerometer installed in the plane (desc of the accelerometer :http://www.gcdataconcepts.com/GCDC_X16-1D_User_Manual.pdf). It's a 3 axis accelerometer, which returns the measures in a CSV file with : time-accX-accY-accZ)

The purpose of those measures were to obtain the path followed by the plane, to actually see the parabola. I did a program on MATLAB :

-to import the measures from the csv file and pu them into variables (it works fine)

-to filter it (with a butterworth filter), because the signal was very noisy, due to the plane's vibration) (it works fine too)

-and then to integer it, twice. And here is the problem : the program run well, but it returns ironical values ; when we begun our parabola at 610 m (2000ft), it ends in the abyssal (approximatly -2000m..).

I don't understand why. I used the cumptrapz function of MATLAB (i just wanted an idea of the path, not a very precise one). I also converted all the mesaures, after having filtered them, to SI system. I multiplied them to 1/2048(accelerometer's gain), then to 9.81 to have it in m/s². I didn't forgot the constant when i integrated (610 m and v0 m/s).

As we did several parabola (10) with different initial velocity (remember : the purpose was to see the influence of several factors such as the velocity and the angle with which we began the parabola), i ran the algorithm with different parabola and there's always the same mistake.

Please find in attachment my different programs:

-importation(i) import the measures into different variable

-filtrage_butterworth filter my measures

-integrale_trapz integrate the signal

-trajectoire return the position to Z and X in order to plot(X,Z), and temps (the vector time) to plot(temps,Z)

Thank you for reading me and I would appreciate any kind off commentaries to my code.

Buzz23

PS : please forgive my approximate english :)

I've just subscribe because I've a problem with a project.

First, I'm a student in France, in prep school. My team and I are working on a project : we study the perfect path for an airplane to be in micro-gravity (it means the only acceleration is the one due to gravity, like what we have here :http://www.airzerog.com/)

So, in order to verify our theoretical model, we experienced in an aerobatic plane (CAP10) and we had a accelerometer installed in the plane (desc of the accelerometer :http://www.gcdataconcepts.com/GCDC_X16-1D_User_Manual.pdf). It's a 3 axis accelerometer, which returns the measures in a CSV file with : time-accX-accY-accZ)

The purpose of those measures were to obtain the path followed by the plane, to actually see the parabola. I did a program on MATLAB :

-to import the measures from the csv file and pu them into variables (it works fine)

-to filter it (with a butterworth filter), because the signal was very noisy, due to the plane's vibration) (it works fine too)

-and then to integer it, twice. And here is the problem : the program run well, but it returns ironical values ; when we begun our parabola at 610 m (2000ft), it ends in the abyssal (approximatly -2000m..).

I don't understand why. I used the cumptrapz function of MATLAB (i just wanted an idea of the path, not a very precise one). I also converted all the mesaures, after having filtered them, to SI system. I multiplied them to 1/2048(accelerometer's gain), then to 9.81 to have it in m/s². I didn't forgot the constant when i integrated (610 m and v0 m/s).

As we did several parabola (10) with different initial velocity (remember : the purpose was to see the influence of several factors such as the velocity and the angle with which we began the parabola), i ran the algorithm with different parabola and there's always the same mistake.

Please find in attachment my different programs:

-importation(i) import the measures into different variable

-filtrage_butterworth filter my measures

-integrale_trapz integrate the signal

-trajectoire return the position to Z and X in order to plot(X,Z), and temps (the vector time) to plot(temps,Z)

Thank you for reading me and I would appreciate any kind off commentaries to my code.

Buzz23

PS : please forgive my approximate english :)