[Tex/LaTex] TikZ-Spring Symbol

tikz-pgf

I would like to insert the symbol of a mechanical spring in a node done with TikZ.

This is my code:

    \documentclass{article}

    \usepackage{tikz}
    \usetikzlibrary{shapes,arrows,calc,positioning}
    \tikzset{
     pinstyle/.style={pin edge={to-,thin,black}},
     block/.style = {draw, rectangle,
     minimum height=1cm,
     align = center
     %   minimum width=2cm
     },
     input/.style = {coordinate,node distance=1cm},
     output/.style = {coordinate,node distance=1cm},
      arrow/.style={draw, -latex,node distance=2cm},
      pinstyle/.style = {pin edge={latex-, black,node distance=2cm}},
        sum/.style = {draw, circle, node distance=1cm},
      gain/.style = {regular polygon, regular polygon sides=3,
      draw, fill=white, text width=1em,
      inner sep=0mm, outer sep=0mm,
      shape border rotate=-90}
      }


    \begin{document}
    \begin{figure}
    \begin{center}
    \begin{tikzpicture}[auto,>=latex',every node/.append style={font=\scriptsize}]

    %DEFINIZIONE BLOCCHI
    \node [input, name=input] {};
    \node [sum, right=of input] (speed_sum) {};
    \node [block, right=of speed_sum] (speed_controller) {$C_{\mathrm{vel}}(s)$};
    \node [gain, right=2cm of speed_controller] (Kt) {$K_{t}$};
    \node [block, right=of Kt] (gvm) {$G_{vM}(s)$};
     \node [block, right=of gvm] (elastico) {$\frac{s\Theta_{M}(s)}{s\Theta_{C}(s)}$};
    \node [output, right=of elastico] (output) {};

    %DEFINIZIONE COLLEGAMENTI IN CATENA DIRETTA
    \draw [->] (input) -- node {$\omega_{M}^{\mathrm{DES}}(s)$}(speed_sum);
    \draw [->] (speed_sum) -- node {$E_{v}(s)$}(speed_controller);
    \draw [->] (speed_controller) -- node {$I^{\mathrm{DES}}(s)=I(s)$}(Kt);
    \draw [->] (Kt) -- node {$C_{\mathrm{M}}(s)$}(gvm);
    \draw [->] (gvm) -- node [name=motor_speed] {$s\theta_{M}(s)$}(elastico);
    \draw [->] (elastico) -- node [name=motor_speed] {$s\theta_{C}(s)$}(output);

    %DEFINIZIONE COLLEGAMENTI FEEDBACK
    \draw [->] (motor_speed) -- ++ (0,-2) -| node [pos=0.99] {$-$} (speed_sum);

\end{tikzpicture}
\end{center}

\caption{Anello di controllo di velocit\`a nel caso co-locato}
\label{fig:speed_loop_colocato}
\end{figure}
\end{document}

The output now is as above (first loop in figure) but i want something as below (second loop in figure):

enter image description here

Exactly where I use

 \node [block, right=of gvm] (elastico) {$\frac{s\Theta_{M}(s)}{s\Theta_{C}(s)}$};

I am asking if there is some \textrm{SPRING_SYMBOL} to reproduce a mechanical spring or what would you do to do it?

Best Answer

You can draw the spring symbol with TikZ. I wrapped it in a macro in case you need to draw the spring more than once, and also to make the TikZ code neater.

I also recommend using \centering instead of \begin{center}.

Note that there are a few options that you can change to modify the look of the spring. I've placed them each on a separate line in the code, and should be quite self explanatory on what they do. If not, just play around with the numbers yourself. These include: segment length, amplitude, pre length and post length. Of course the coordinates used for the zigzag line can be modified as well.

Code:

\documentclass{article}

\usepackage{tikz}
\usetikzlibrary{shapes,arrows,calc,positioning,decorations.pathmorphing} % <------- add new library
\newcommand*{\drawspring}{%
    \tikz \draw[decorate,decoration={
        zigzag,
        segment length=0.2cm,
        amplitude=2mm,
        pre length=.1cm, 
        post length=.1cm}] (0,0)--(1,0);} % <-------- define a macro to draw the spring (for conciseness)

\tikzset{
    pinstyle/.style={pin edge={to-,thin,black}},
    block/.style = {draw, rectangle,
        minimum height=1cm,
        align = center
        %   minimum width=2cm
    },
    input/.style = {coordinate,node distance=1cm},
    output/.style = {coordinate,node distance=1cm},
    arrow/.style={draw, -latex,node distance=2cm},
    pinstyle/.style = {pin edge={latex-, black,node distance=2cm}},
    sum/.style = {draw, circle, node distance=1cm},
    gain/.style = {regular polygon, regular polygon sides=3,
        draw, fill=white, text width=1em,
        inner sep=0mm, outer sep=0mm,
        shape border rotate=-90}
}

\begin{document}
    \begin{figure}
    \centering
    \begin{tikzpicture}[auto,>=latex',every node/.append style={font=\scriptsize}]

    %DEFINIZIONE BLOCCHI
    \node [input,name=input] {};
    \node [sum,right=of input] (speed_sum) {};
    \node [block,right=of speed_sum] (speed_controller) {$C_{\mathrm{vel}}(s)$};
    \node [gain, right=2cm of speed_controller] (Kt) {$K_{t}$};
    \node [block, right=of Kt] (gvm) {$G_{vM}(s)$};
    \node [block,right=of gvm] (elastico) {\drawspring}; % <--------- draw the spring here in the node
    \node [output, right=of elastico] (output) {};

    %DEFINIZIONE COLLEGAMENTI IN CATENA DIRETTA
    \draw [->] (input) -- node {$\omega_{M}^{\mathrm{DES}}(s)$}(speed_sum);
    \draw [->] (speed_sum) -- node {$E_{v}(s)$}(speed_controller);
    \draw [->] (speed_controller) -- node {$I^{\mathrm{DES}}(s)=I(s)$}(Kt);
    \draw [->] (Kt) -- node {$C_{\mathrm{M}}(s)$}(gvm);
    \draw [->] (gvm) -- node [name=motor_speed] {$s\theta_{M}(s)$}(elastico);
    \draw [->] (elastico) -- node [name=motor_speed] {$s\theta_{C}(s)$}(output);

    %DEFINIZIONE COLLEGAMENTI FEEDBACK
    \draw [->] (motor_speed) -- ++ (0,-2) -| node [pos=0.99] {$-$} (speed_sum);
    \end{tikzpicture}
    \caption{Anello di controllo di velocit\`a nel caso co-locato}
    \label{fig:speed_loop_colocato}
\end{figure}
\end{document}

Output

output image

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