epicycle

• 本轮是一种在均轮上运动的辅助圆，其圆心沿均轮运动，行星沿本轮运动；也指一个圆在另一个圆内或外滚动时，其圆周上一点所描出的轨迹，即外摆线或内摆线。

A circle that rolls either inside or outside another circle, generating curves known as epicycloids or hypocycloids.

1. Rolling circleC2formalscientific

   A circle that rolls around the inside or outside of another fixed circle, generating a curve known as an epicycloid or hypocycloid.

   滚动圆

   • The path traced by a point on an epicycle is a complex curve.
   • Ancient astronomers used epicycles to explain planetary motion.
   • The gear mechanism relies on the principle of an epicycle.