Use a Simulink block as a regular MATLAB function

Hi everyone,

I am new to the MATLAB aerospace toolbox, and intend to use it quite intensively in the coming time. The aerospace toolbox has a very elaborate set of functions, such as the aerodynamic forces and moments block or the simple variable mass 6DoF equations of motion (Euler angles). These blocks are of course very useful in a Simulink environment, where the blocks are connected in a certain way and a time simulation can be run.

However, I was wondering whether it is also possible to call the underlying functions of these blocks as regular MATLAB functions. For example, taking the ISA Atmosphere Model as an example, I could use it as a block within a Simulink environment. For this specific example, I know that I can also call the function as a regular MATLAB function by calling:

[T a p rho] = atmosisa(h)

However, this function call is not indicated anywhere on this page. How do I know how to call the underlying functions of any of the blocks available within the MATLAB aerospace toolbox? That is, why is there no link from the "block function" page to this page and how can I see the function page corresponding to a general Simulink block?

Thanks in advance.

Answer 1

[Shashwat Bajpai]

Hi Sam,

I would suggest looking at the description of the blocks in the blockset page and the description of functions in the function page to know the under lying functions being used in the blocks.

Hope this helps!

[Sam]

Hi Shashwat,

Thank you for your answer. I have of course checked out the description of the blocks in the MATLAB documentation. Naturally, you could copy those equations and write the functions yourself. However, seeing as the blocks contain a natural input-output structure that can be easily rewritten as:

output = function(input)
something...
end

It would seem only logical to me that it'd be possible to call these blocks' functions in a function-like manner, too. Copying manually seems like a whole lot of error-prone work to me.

[Shashwat Bajpai]

The blocks in the aerospace blockset are developed over pre-existing functions in the aerospace toolbox and you can get those by referring the links i mentioned earlier. For example the block Direction Cosine Matrix to Quaternions uses the function dcm2quat and this can be understood by their respective descriptions.

[Sam]

Dear Shashwat,

Thanks again for your response. I see how in your example the underlying function name is given by the description of the block in the image. However, taking a somewhat more complicated example of this 6DoF Variable Mass Wind (Quaternion) block, I don't see a reference to some underlying function:

[Ve, Xe, . . ., domegadt, Abb] = 6DoFVariableMassWindQuaternion(Fxyz, Mxyz, . . ., dldt, I)

Or something of the like. Am I missing something here?

Thanks in advance.

[Shashwat Bajpai]

Hi Sam,

The functionalities of blockset are developed using Simulink and it's capabilities. They have some common functions but not all the blocks have an underlying function as they were developed using Simulink. For the blocks which do have the same functions you can refer the description and use them accordingly.

[Sam]

Hi Shashwat,

That explains it. Thanks for your support.

Kind regards.