Hi @ahmad nouri
I can understand the frustration that can come with manually designing an observer, as it often requires completing numerous tedious tasks, such as listing out all relevant equations, substituting them carefully, performing differentiations correctly, and manipulating algebraic terms. This process can indeed be cumbersome.
Perhaps in the near future, we may see the development of a dedicated Nonlinear Control Toolbox that could streamline this process.
In the meantime, I would suggest considering the use of this Sliding Mode Observer block for your current work.
