e/Double inverted pendulum

Information
has gloss	eng: A double inverted pendulum is analog to the inverted pendulum. Where the single inverted pendulum has a mass at the endpoint of the pendulum, the double inverted pendulum has a second pendulum. Usually the double pendulum is mounted on a cart. The double pendulum is unstable, meaning that it will fall down unless the cart is controlled by some control algorithm to keep the pendulums upright.
lexicalization	eng: double inverted pendulum
instance of	(noun) an apparatus consisting of an object mounted so that it swings freely under the influence of gravity pendulum