TITLE: Mathematical status of Jansen's linkage
QUESTION [5 upvotes]: Does Jansen's linkage mechanism achieve a genuinely flat segment of the foot's cycle or merely an approximation?

Dimensions of mechanism given here, though presumably the actual measurements require more precise definition.

REPLY [3 votes]: Simply because the coordinates  of all points are linked by polynomial equations (obtainable from Pythagoras), the curve is given by an algebraic equation. Such an equation could describe a line, but nothing that is partly curved and partly a line.