% ---------------------------------------------------------------
% Realimentação de estados:  u = N r - K x ,  planta x_dot = A x + B u
% Bibliotecas (chunk .qmd): arrows.meta, positioning, calc
% ---------------------------------------------------------------
\begin{tikzpicture}[>=Latex, line width=0.9pt,
  block/.style={draw, minimum width=1.0cm, minimum height=1.0cm, fill=blue!8},
  sum/.style={draw, circle, minimum size=8mm, inner sep=0pt}]

  \node (r)          at (-1.5,0) {$r$};
  \node[block] (N)   at (0,0)    {$N$};
  \node[sum]   (si)  at (1.6,0)  {};
  \node[block] (B)   at (3.1,0)  {$\mathbf{B}$};
  \node[sum]   (ss)  at (4.6,0)  {};
  \node[block] (int) at (6.1,0)  {$\displaystyle\int$};
  \node[block] (C)   at (9.4,0)  {$\mathbf{C}$};
  \node (y)          at (11.0,0) {$y$};

  \node[block] (A)   at (7.4,-2.0) {$\mathbf{A}$};
  \node[block] (K)   at (3.1,-3.4) {$\mathbf{K}$};

  \coordinate (x) at (7.4,0);

  % sinais
  \node[font=\scriptsize] at ($(si)+(-0.30,0.30)$) {$+$};
  \node[font=\scriptsize] at ($(si)+(0,-0.42)$)    {$-$};
  \node[font=\scriptsize] at ($(ss)+(-0.30,0.30)$) {$+$};
  \node[font=\scriptsize] at ($(ss)+(0,-0.42)$)    {$+$};

  % cadeia direta
  \draw[->] (r) -- (N);
  \draw[->] (N) -- (si);
  \draw[->] (si) -- (B) node[midway, above] {$u$};
  \draw[->] (B) -- (ss);
  \draw[->] (ss) -- (int) node[midway, above] {$\dot{\mathbf{x}}$};
  \draw[->] (int) -- (C) node[pos=0.42, above] {$\mathbf{x}$};
  \draw[->] (C) -- (y);

  % realimentação A (+)
  \fill (x) circle (1.6pt);
  \draw[-]  (x) -- (A.north);
  \draw[->] (A.west) -| (ss);

  % realimentação de estados -K
  \draw[-]  (7.4,0) -- (7.4,-3.4) -- (K.east);
  \draw[->] (K.west) -| (si);

\end{tikzpicture}