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I am trying to improve this picture made in Word by using Tikz. I have made some advancements but there are some questions that kept me stuck.

4 bar mechanism parameters

  1. Regarding the angles, I need to draw a line at some point paralell to the X local axis. The same for \theta_0 but with respect to X fixed axis. This is well explained by @Jake in this post. However, I would like to specify the lenght of the segment.

  2. Once created those lines, how do I draw the angle mark? To draw this type of arrow I need somehow to refer to that line. In the MWE I have made the arrow for $\alpha$, but it was easy (once I learned how to do it) as I had the three coordinates. Is there some way to do it from the possible answer to Q1?

  3. How do I reposition the name of the vectors using draw?

This is my MWE:

\documentclass{article}
\usepackage{graphicx} % Required for inserting images
\usepackage{tikz}
\usetikzlibrary{angles, calc, arrows.meta,quotes}
\usepackage{kinematikz}

\begin{document}


\begin{figure}
    \centering
        \begin{tikzpicture}[
        arr/.style = {-Stealth, semithick},
        dot/.style = {circle,inner sep=1pt,fill,label={#1},name=#1},
        extended line/.style={shorten <=-#1},
        extended line/.default=1cm
        ]
            \draw [<->] (0,5) node[left]{$Y$} -- (0,0) -- (5,0) node[below]{$X$};  % Draws fixed RS
            \draw[dashed] (2,0) node[below] {$X_A$} -- (2,2);
            \draw[dashed] (0,2) node[left] {$Y_A$} -- (2,2);


        \coordinate [label={[label distance=0.5cm]235:$A$}] (A) at (2,2);
        \coordinate (B) at (3,5);
        \coordinate (C) at (6,7);
        \coordinate (D) at (9,4);
        \coordinate (E) at (4,8);
        \coordinate (M) at ($(B)!(E)!(C)$);    % E over BC line
        \coordinate (Y) at ($(A)!0.5!90:(D)$); % AD, scale factor 0.5 rotated 90º
        \coordinate (X) at ($(A)!0.5!0:(D)$);  % AD, scale factor 0.5 rotated 0º

        \draw (C) -- (E);
        \draw (A) -- (E);

        \fill [black] (B) circle [radius=2pt];
        \fill [black] ($(B)!(M)!(C)$) circle [radius=2pt];
        \fill [black] (C) circle [radius=2pt];
        \fill [red] (E) circle [radius=2pt];

        \draw (D)--(A)--(B) pic [&quot;$\alpha$&quot;,draw,-&gt;, angle radius=1cm]{angle = D--A--B};

        \draw[arr] (B) to [&quot;$\vec{r_b}$&quot;] (C);
        \draw[arr] (D) to [&quot;$\vec{r_c}$&quot;] (C);
        \draw[arr] (B) to [&quot;$\vec{r_{cx}}$&quot;] (M);
        \draw[arr] (M) to [&quot;$\vec{r_{cy}}$&quot;] (E);
        \draw (B) -- +($(X)-(A)$); % Paralela a una línea que pasa por un punto dado
        \draw (D) -- +($(X)-(A)$);
        \draw (A) -- (6,2);

        \draw[orange, arr] (A) to [&quot;$\vec{x}$&quot;] (X); % X local axis
        \draw[orange, arr] (A) to [&quot;$\vec{y}$&quot;] (Y); % Y local axis

        \pic (pointA) at (A) {frame pivot rounded}; % Frame pivot A
        \pic (pointD) at (D) {frame pivot rounded}; % Frame pivot D




\end{tikzpicture}


\caption{Caption}
\label{fig:enter-label}




\end{figure}


\end{document}

enter image description here

Altough the package kinematikz may be useful for a more beautiful drawing of the mechanism I am using it just for the frame pivots.

Qrrbrbirlbel
  • 119,821
Frank R.
  • 53
  • 1
  • to ["$\vec{x}$" at end] moves the node at the end of the to path. (You can also just use a node {…} after the target coordinate.)
    • – Qrrbrbirlbel Oct 16 '23 at 12:19
  • 2
    In regards to 1, something like the norm cs could help but nowadays we can use a sloped pic to draw a local coordinate system (here green) that is tangent to some line at some point . – Qrrbrbirlbel Oct 16 '23 at 12:27