Simulink - EOM in matrix form

Hi All,

I need to model an EOM , representing a 3 DOF point mass with a pendulum, defined by mean of 2 angles, total 5 DOF, of the kind

where λ and τ are the resp. the generalized coordinates and forces, and where μ is the time derivative of λ.

I was starting to model a block with as output with some integrators to calculate the inputs. As additional inputs a set of constant and the generalized forces, that then will be a function of a control feedback.

I have already the definition of the 3 matrices, M,C ad G, but I have some issues working with them correctly. I prepared a set of Matlab function blocks with the symbolic definitions of the matrices and the variables that are needed. In particular I receive an error when multiplying the C matrix times μ vector.

Then I need an advice to manage the signals in input and output. I was thinking of using a MUX/DEMUX pair to route the coordinates signal around the blocks, but not really sure of this method.

Thanks for help.

SS

[Stefano sala]

I succeeded in solving the errors form the matlab function block.

Being a 5x1 input (generalized forces) and a 5x1 output (generalized coordinates second derivative) i've noticed that the dimension during the integration the result is not automatically correct dimensionally. so the problem. I solved that splitting the signal in vectors and integrating one by one each of them, feedbacking the single 1x1 signals.

not really sure about the result but anyway, going further.