<p>An animated depiction of a <a href="https://en.wikipedia.org/wiki/en:Roberts%27_linkage" class="extiw" title="w:en:Roberts' linkage">w:en:Roberts' linkage</a> (converts rotational motion to approximate straight-line motion)<br>
Link ratios are: L1 = L3 = L4. L2 = 1/2 * L1. The triangle is isosceles (the two non L2 sides are of equal length, and equal to L1)<br></p>
In this example: L1=4, L2=2, L3=4 and L4=4.
<a href="//commons.wikimedia.org/w/index.php?title=User:Van_helsing&amp;action=edit&amp;redlink=1" class="new" title="User:Van helsing (page does not exist)">Van helsing</a>
CC BY 2.5
self-made largely based on <a rel="nofollow" class="external text" href="http://historical.library.cornell.edu/cgi-bin/cul.math/docviewer?did=Kemp009&amp;seq=20&amp;frames=0&amp;view=50"><i>"How to draw a straight line, by A.B. Kempe, B.A."</i></a>, <a rel="nofollow" class="external autonumber" href="http://iel.ucdavis.edu/design/fourbar/fourbarRoberts.html">[1]</a> and <a rel="nofollow" class="external autonumber" href="http://kmoddl.library.cornell.edu/model.php?m=277">[2]</a>