Initializing a value at the beginning of a Feedback loop in SIMULINK

Question

Sreekanth Nandakumar 2019-7-31

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/474247-initializing-a-value-at-the-beginning-of-a-feedback-loop-in-simulink

评论： Sreekanth Nandakumar 2019-8-2

Hello all,

I am attaching a simplified version of a SIMULINK model with a feed back loop. In the model, the variable 'x' is involved in a feedback loop. x is a 3X1 Matrix with values x = [0.9 ; 0 ; 0] which I have initialized inside the MATLAB fcn block. This is a state equation and the x gets updated after a series of equations. Now how will I use the updated value in the next time step ? Even though the updated value is feedbacked into the input, the initial value of x inside the MATLAB fcn is still used in the calculation as the initializing comes inside the fcn. How to solve this issue ?

2 个评论
显示无隐藏无

Renato SL 2019-7-31

编辑：Renato SL 2019-7-31

Can you show us what happens inside fcn ?

Sreekanth Nandakumar 2019-8-2

It is a generic model to just ask how to do it. The original model can't be posted here due to confidentiality.

请先登录，再进行评论。

请先登录，再回答此问题。

Answer 1

Raj 2019-7-31

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/474247-initializing-a-value-at-the-beginning-of-a-feedback-loop-in-simulink#answer_385587

Instead of initializing the value of 'x' inside MATLAB function, try the following:

1) Instead of directly feeding x1 at x (which is not correct by the way as it becomes an algebraic loop!) pass x1 through a unit delay block before connecting at x.

2) Double click on the unit delay block and set your initial conditions as the value you have mentioned in your question. Now this value will be used only during first cycle of execution to compute the first output which will be fed back to compute the second output during second execution cycle and so on.