How can I draw two lines to a block?

Question

I'm trying to draw a control block, but I got problem to connect two input to a block

How can draw a line from the u1 to the estimator without drawing on the estimator block?

This is what I tried

\tikzstyle{block} = [draw, rectangle, 
    minimum height=1cm, minimum width=2cm]
\tikzstyle{input} = [coordinate]
\tikzstyle{output} = [coordinate]
\tikzstyle{arrow}=[draw, -latex]
\tikzstyle{pinstyle} = [pin edge={latex-, black}]
\tikzstyle{sum} = [draw, circle, node distance=1cm]

% The block diagram code is probably more verbose than necessary
\begin{tikzpicture}[auto, node distance=2cm,>=latex']
   % We start by placing the blocks
   \node [input, name=input] {};
   \node [sum, right of=input] (sum) {};
   \node [block, right of=sum] (controller) {Controller};
   \node [block, right of=controller, node distance=3cm] (system) {System};         
   \node [output, right of=system] (output) {};

   %Connect
   \draw [arrow] (input) -- node {$y_{_1ref}$} (sum);
   \draw [arrow] (sum) -- node [name=y_err_one] {$e_{_1}$} (controller);
   \draw [arrow] (controller) -- node [name=u_one] {$u_{_1}$} (system);
   \draw [arrow] (system) -- node [name=y_one] {$y_{_1}$} (output);

   %Second leader
   \node [block, below of=u_one] (estimator_one) {Estimator};
   %\node [block, left of=estimator_one, node distance=3cm] (cs_to_js_one) {CS2JS};
   %\node [block, left of=cs_to_js_one] (for_kin) {Forward Kinematics};

   %Connect
   \draw [arrow] (y_one) |- (estimator_one);
   \draw [arrow] (u_one) |- (estimator_one);
   \draw [arrow] (estimator_one) -| node[pos=0.99] {$-$} 
        node [near end, name=y_est_one] {$y_{_1est}$} (sum);


\end{tikzpicture}

Answer 1

In the code below the main change is

   \path [arrow] (u_one) -- ($(estimator_one.north)+(0,.5)$) 
                         -| ($(estimator_one.east)+(1,1)$)
                         -| ($(estimator_one.east)+(1,0)$)
                         --(estimator_one.east);

which requires \usetikzlibrary{calc}

I also changed tikstyle= to tikzset, as discussed in Should \tikzset or \tikzstyle be used to define TikZ styles?

\documentclass{standalone}
\usepackage{tikz}
\usetikzlibrary{arrows,calc}

\tikzset{
        block/.style = {draw, rectangle, 
                        minimum height=1cm, 
                        minimum width=2cm},
        input/.style = {coordinate},
        output/.style = {coordinate},
        arrow/.style={draw, -latex},
        pinstyle/.style = {pin edge={latex-, black}},
        sum/.style = {draw, circle, node distance=1cm}
}

\begin{document}
% The block diagram code is probably more verbose than necessary
\begin{tikzpicture}[auto, node distance=2cm,>=latex']
   % We start by placing the blocks
   \node [input, name=input] {};
   \node [sum, right of=input] (sum) {};
   \node [block, right of=sum] (controller) {Controller};
   \node [block, right of=controller, node distance=3cm] (system) {System};         
   \node [output, right of=system] (output) {};

   %Connect
   \draw [arrow] (input) -- node {$y_{_1ref}$} (sum);
   \draw [arrow] (sum) -- node [name=y_err_one] {$e_{_1}$} (controller);
   \draw [arrow] (controller) -- node [name=u_one] {$u_{_1}$} (system);
   \draw [arrow] (system) -- node [name=y_one] {$y_{_1}$} (output);

   %Second leader
   \node [block, below of=u_one] (estimator_one) {Estimator};
   %\node [block, left of=estimator_one, node distance=3cm] (cs_to_js_one) {CS2JS};
   %\node [block, left of=cs_to_js_one] (for_kin) {Forward Kinematics};

   %Connect
   \draw [arrow] (y_one) |- (estimator_one);
   \path [arrow] (u_one) -- ($(estimator_one.north)+(0,.5)$) -| ($(estimator_one.east)+(1,1)$)-| ($(estimator_one.east)+(1,0)$)--(estimator_one.east);
   \draw [arrow] (estimator_one) -| node[pos=0.99] {$-$} 
        node [near end, name=y_est_one] {$y_{_1est}$} (sum);


\end{tikzpicture}
\end{document}