Rotation Matrix with euler angles

Das Programm soll Input: 3 euler angles one number sigma (meaning: standard deviation for the assumed measuring accuracy)

The code search with the euler angles the rotationmatrix they are 18

g11 + random number

g21 + random number

g11 + random number

g31 + random number

... g33 + random number

Each of the random numbers should then correspond to an N (0, sigma) -distributed random variable. It is therefore a list of simulated measurements.

[James Tursa]

What is your question?

[Image Analyst]

What's being rotated? It looks like you can just use randn() to compute noise and then add to your g matrix.

Why do you have 18 Euler values instead of 6 (x, y, z, and three directions/angles)?

When you say "The code search", exactly WHAT is your code supposed to search FOR?

[Rashiqah Shahzad]

I am searching to a rotationmatrix input are the three euler angles.

You have a object with a coordinate system x y z = in x direction a seperate coodinate system -> 3

in y direction -> 3

in z achse -> 6 calculate there are 3 in x 3 in y 3 in z 9

then you have on you object a coodinate system with also 3 x 3y 3 z achse -> 18 Euler values.

Perhaps you understand on the picture. The prof want that i write a code on the problem that i have shown you. But i dont know how i write a input or output my matlab knowledge is by zero. Please can you help me?

[Image Analyst]

Having a little trouble understanding your English. Searching means to find or look for something.

So you have 4 values (x,y,z) for the point location, and then 3 more angles (which can be an x,y,z unit vector) to define the orientation of the object at that point. That's 6 numbers. I don't know where the other 12 are coming from.

You didn't attach a picture. Be sure to use the frame icon to upload the diagram showing the 18 values on it.

Wikipedia Euler Angles

[Rashiqah Shahzad]

hey dear user i am so thankful that you show my problem. i am from germany i can‘t speak englisch.

The problen my prof has give me is that i have a input datei with 3 euler angles and as a output a rotationmatrix with random numbers.

the are total 18 numbers.

[Rashiqah Shahzad]

please can anyone help me it is very important for me or give me a advice.

Answer 1

[James Tursa]

The best I can guess is you are given three Euler angles with a sigma for noise, and you want to output a corresponding rotation matrix. There are two approches you might try. First, you might start with the SpinCalc conversion routine from the FEX by John Fuller

https://www.mathworks.com/matlabcentral/fileexchange/20696-function-to-convert-between-dcm-euler-angles-quaternions-and-euler-vectors

Then you can either add randn(1,3)*sigma noise to the Euler angles prior to calling SpinCalc, or add randn(3,3)*sigma noise to the rotation matrix elements after you call SpinCalc. The first method will leave you with a valid rotation matrix. The second method will leave you with slightly non-valid rotation matrix. I am not sure which method gives you what you want. E.g.,

>> EA = [20 30 40] % Euler angles in degrees
EA =
    20    30    40
>> sigma = 2
sigma =
     2
>> DCM = SpinCalc('EA123toDCM',EA+randn(1,3)*sigma,1e-10,0) % roll,pitch,yaw
DCM =
    0.6930    0.7029   -0.1602
   -0.5489    0.6585    0.5148
    0.4673   -0.2689    0.8422
>> SpinCalc('DCMtoEA123',DCM,1e-10,0) % try to recover the original
ans =
   17.7059   27.8623   38.3810

[Rashiqah Shahzad]

Thank you every much it helps me a lot thank you.