An extremely simple system that produces a wide range of curves.
All that is happening is rotation at a constant speed about an axis which is itself rotating about an axis, (rotating about another axis).
There are 4 parameters per arm :
radius, 2 angles for the rotation axis (precession & nutation), and rate of rotation.
When the axes are all parallel the resulting curves are planar and include cardioids, nephroids, epicycloids and many others.
When the second axis is perpendicular to the first, and the rates of rotation are coprime, the curves are torus knots.
When the rates of rotation do not have a common factor the curve is chaotic.