Draw snake around the rectangular node

Question

I want to draw the "coiled snake " around the rectangle named "Obstacle". The rectangle consist of node "O". I could not figure it out as I am new to tikz. can anyone give me good suggestion in this? Thanks in Advance

Here is the code

\documentclass{article}
\usepackage{tikz}
\usetikzlibrary{snakes}
\begin{document}

\begin{tikzpicture}
\tikzstyle{block} = [draw,rounded corners,thin,fill= gray!20,  rectangle,   thick,align=center]
 % Draw axes
 % \node (0,0)(a) {$\theta$}
 \draw [<->,thick] (0,2) node (yaxis) [above] {$y$}
    |- (2,0) node (xaxis) [right] {$x$};
%\draw [gray](0,0)+(0.5,0)arc(0:45:0.5); 
%\path (0,0)++ (22.5:0.7)node{$\theta$};
% Draw two intersecting lines

 \draw (1.2,1.2)coordinate(a_2);
%Draw vehicle
\draw [rotate =20](a_2)+(0.5,0)coordinate(V_c)node[block,minimum width=28,minimum height=18, rotate=20](a){};
\draw[snake=coil,](a)++(45:3)node[block,rotate=45,segment aspect=10,,minimum height=50,font =\large](O){Obstacle};

%Draw body axis
 \draw [->,rotate =20,thick] (V_c) -- ++(0,0.7)node[rotate=20](yaxis)[above]{$y_{b}$};
% \draw [->,rotate =45,thick] (V_c)++(-0.22,0.5) -- ++(0,0.7)node[rotate=45](yaxis)[above]{$v_{y}$};
  \draw [->,rotate =20,thick] (V_c) -- ++(0.8,0)node[rotate=20](yaxis)[below]{$x_{b}$};
  %draw Dimension of distance to obstacle
  \draw[dashed,rotate=45] (a.22) -- (O);
  \draw[snake=brace,raise snake=2pt,gap around snake =2pt,rotate=45] (a.22) -- (O);%for curly bracket
  \path (V_c)+(0.5,0)--coordinate(L)(O);
  \draw [rotate =45] (L)+(0.1,0.5) node[rotate=45]{$L_i$};
  \draw[->](a.10)--+(45:0.5)node[rotate=45,below]{$v$};
 \end{tikzpicture}
  \end{document}

Answer 1

Generally, for these purposes it is necessary to use the so called late options (see 16.14 Late Code and Late Options on the pgfmanual). This is a proof of concept exploiting append after command:

\documentclass[border=10pt,tikz,png]{standalone}
\usepackage{tikz}
\usetikzlibrary{decorations.pathmorphing}

\tikzset{block/.style={draw,rounded corners,thin,fill= gray!20,rectangle,thick,align=center}}
\tikzset{decorate this node/.style={
    append after command={
      \pgfextra{
        \draw[decoration type,decorate,#1](\tikzlastnode.south west)rectangle(\tikzlastnode.north east);
      }
    }
  },
  decoration type/.style={
    decoration={coil,raise=4pt,amplitude=1pt,segment length=6pt}
  }
}

\begin{document}

\begin{tikzpicture}
\node[block,rotate=45,segment aspect=10,minimum height=50,font =\large,decorate this node={rotate=45}] (O) at(0,0) {Obstacle};
\end{tikzpicture}
\end{document}

The result:

Some remarks

The snakes library has been superseeded by decorations. Moreover, I switched the deprecated tikzstyle into tikzset as per Should \tikzset or \tikzstyle be used to define TikZ styles?.

Finally, for what concern the style decorate this node, be carefull to keep consistence with the transformations you apply to the node: see the option rotate=45 passed also to the style.