I am trying to pass arrows above the nodes on the image and join the "saturation" block. If you have an idea, I'm interested. Second thing, I wish I could put a second right angle on the arrow before reaching the west part of the sum. Any help will be welcome
Here's the code :
\documentclass[border=0.2cm]{standalone}
% More defined colors
\usepackage[dvipsnames]{xcolor}
\usepackage{comment}
% Required package
\usepackage{tikz}
\usepackage{tabularx}
\usetikzlibrary{fit,positioning,shapes,arrows,decorations.pathreplacing}
\begin{document}
\tikzstyle{pinstyle}=[pin edge={to-,thin,black}]
\begin{tikzpicture}
%% B
%%sum
\foreach \i in{1,2,3}{
\node[draw,
circle,
minimum size=0.6cm] at (0.5\i,-1\i ) (sum\i) {};
\draw (sum\i.north east) -- (sum\i.south west)
(sum\i.north west) -- (sum\i.south east);
\draw (sum\i.north east) -- (sum\i.south west)
(sum\i.north west) -- (sum\i.south east);
\node[above=-1pt] at (sum\i.center){\tiny $+$};
\node[left=-1pt] at (sum\i.center){\tiny $-$};
}
%%fast non linear
\node[draw,rectangle,minimum width=1cm,minimum height=3cm,align=center,right=1.5 of sum2] (saturation) {Saturation & \ limiteur de taux};
\node[draw,rectangle,fill=green!60!black,minimum width=1cm,minimum height=3cm,align=center,right=1.5 of saturation] (fast) {Modèle \ non linéaire \ FAST};
\node[draw,rectangle, minimum size = 1.5cm, align=center, above left=of fast.north west ] (cpb){Contrôle \ CPB};
\node[draw,rectangle, minimum size = 1.5cm, align=center, below left=of fast.south west ] (ipb){Contrôle \ IPB};
%%Arrow
\draw[-stealth] ([yshift=20pt]fast.east) -- ++ (1cm,0) |- (cpb.east)
node[midway,above]{};
\draw[-stealth] ([yshift=-20pt]fast.east) -- ++ (1cm,0) |- (ipb.east)
node[midway,above]{};
\draw[-stealth] ([yshift=10pt]ipb.west) -- ++ (-0.5cm,0) -|(sum3.west) node[midway,above]{};
\draw[-stealth] ([yshift=0pt]ipb.west) -- ++ (-0.5cm,0) -| (sum2.west) node[midway,above]{};
\draw[-stealth] ([yshift=-10pt]ipb.west) -- ++ (-0.5cm,0) -| (sum1.west) node[midway,above]{};
%%arrow cpb
\draw[-stealth] (cpb.west) -- ++ (-0.5cm,0) -| (sum1.north) node[midway,above]{};
\draw[-stealth] (cpb.west) -- ++ (-0.5cm,0) -| (sum2.north) node[midway,above]{};
\draw[-stealth] (cpb.west) -- ++ (-0.5cm,0) -| (sum3.north) node[midway,above]{};
\end{tikzpicture}
\end{document}


spath3library should help you a lot. – SebGlav Sep 28 '21 at 15:30