\tikzset{
    pulley/.pic=
    {
        \draw (0,0) -- (-0.3,0);
        \draw (-0.3,-0.2) circle [radius=0.2];
        \draw (-0.3,-0.2) circle [radius=0.04];
    },
    whiteboard/.pic=
    {
        \draw[line width=1mm, color=gray, fill=lightgray!70] (0,0) rectangle (4,2.5);
    },
    masspoint/.pic=
    {
        \draw[fill=white] (0,0) circle (0.2) node {m};
    },
    rail/.pic=
    {
        \draw[fill=gray!60] (0,0.05) rectangle (4,-0.05);
    },
    scara/.pic=
    {
        \def \wall {0.05};
        \draw[fill=gray!60,rounded corners] ({-\x-\wall},{-\y-\wall}) rectangle ({\x+\wall},{\y+\wall});
        \draw[fill=lightgray!70,rounded corners] ({-\x},{-\y+\wall}) rectangle ({\x},{\y});
        \begin{scope}[shift={(-\x/2,-\y+\wall/2)},rotate=\alpha, x=7mm, y=7mm]
            \draw[fill=red](-0.1,-0.1) rectangle (1.6,0.1);
            \begin{scope}[shift={(1.65,0)}]
                \begin{scope}[rotate=\beta]
                    \draw[fill=red](-0.1,-0.1) rectangle (1.4,0.1);
                    \draw[fill=red](1.4,0) circle (0.2);
                \end{scope}
            \end{scope}
        \end{scope}
    }
}