Simulink matrix multiplication error when passing matrix to model

Hi,

I am trying to create a simulink model that does a few matrix multiplications but I cant seem to get the inputs right.

This is the setup of the model. Wind and gravity are 3x1 vectors and DCM is a 3x3 matrix coming from the 6DOF fixed mass model.

The model itself looks like this:

Given the dimensions the expected multiplications should result in (3x3) * (3x1) = (3x1).

However, when running the simulation i get several dimension mismatch errors:

Error using uavsim (line 7)
Error due to multiple causes.
Caused by:
    Error using uavsim (line 7)
    Error in port widths or dimensions. 'Output Port 1' of 'storm_uav/Constant2' is a [3x1] matrix.
    Error using uavsim (line 7)
    Error in port widths or dimensions. 'Input Port 1' of 'storm_uav/Model5' is a one dimensional vector with 1 elements.

I don't know why this is happening as the dimensions are correct in my opinion. Is there a mistake in the way I pass the vectors and the matrix to the model?

Help is greatly appreciated.

Thanks

Answer 1

[Harald]

Hi,

if DCM is 3x3, I'd expect the signal dimensions to indicate that. However, it shows 9, so I'd think that this is really a vector with 9 elements.

If that is the case, you can use a Reshape block to convert it to a 3x3 matrix. Depending on the ordering of elements in the vector, you may need to use a Transpose block on top of it.

Best wishes,

Harald