Student's Work: Symmetric rolling motion
Symmetric slider-inverted-slider mechanism
For the displayed mechanism the polodes are congruent parabolas.
The fixed parabola coloured in blue has the focal point M.
The moving parabola coloured in green has the focal point A.
The locus of all points, which are instantaneously at an inflection point of their path,
is the so-called inflection circle (orange), which touches the pole tangent (red) in P.
The antipode of P is known as inflection pole W.
The intersection between the affine normal (red dashed line) in P with respect to
the fixed polode and the inflection circle results in the Ball point U.
This is the only point, which is instantaneously at an undulation point of its path.
The locus of all points which are instantaneously at a vertex of their path is called cubic
of stationary curvature (red). This cubic contains the instantaneous pole P,
the Ball point U and the focal points of the moving polode,
which are the Burmester points of the constrained motion.
Due to reasons of symmetry, the cubic of stationary curvature splits up
into a circle and a straight line if P is at the vertex of the parabola.
Created by Christoph Teufel (2014) using Cinderella.