# Inverted Pendulum

An inverted pendulum is a pendulum which has its center of mass above its pivot point. It is often implemented with the pivot point mounted on a cart that can move horizontally and may be called a cart and pole. Most applications limit the pendulum to 1 degree of freedom by affixing the pole to an axis of rotation. Whereas a normal pendulum is stable when hanging downwards, an inverted pendulum is inherently unstable, and must be actively balanced in order to remain upright; this can be done either by applying a torque at the pivot point, by moving the pivot point horizontally as part of a feedback system, changing the rate of rotation of a mass mounted on the pendulum on an axis parallel to the pivot axis and thereby generating a net torque on the pendulum, or by oscillating the pivot point vertically. A simple demonstration of moving the pivot point in a feedback system is achieved by balancing an upturned broomstick on the end of one's finger. The inverted pendulum is a classic problem in dynamics and control theory and is used as a benchmark for testing control strategies.

A second type of inverted pendulum is a tiltmeter for tall structures which consists of a wire anchored to the bottom of the foundation and attached to a float in a pool of oil at the top of the structure which has devices for measuring movement of the neutral position of the float away from its original position.

### Other articles related to "inverted pendulum, inverted, pendulum":

Science And Technology Of The Han Dynasty - Mechanical and Hydraulic Engineering - Seismometer
... The trigger mechanism was an inverted pendulum (which the Book of the Later Han calls the "central column") that, if disturbed by the ground tremors of earthquakes located near or far away, would swing and ... that Zhang's seismometer had cranks and levers which were disturbed by the inverted pendulum, his contemporary Akitsune Imamura (1870–1948) argued that the inverted ... up into their jaws after the first one had dropped, Imamura asserted that the pin of the pendulum would have been locked into the slot it had entered and thus immobilized the instrument until it was reset ...
Examples of Inverted Pendulums
... There are many instances of the inverted pendulum model both man made and found in the natural world ... Arguably the most prevalent example of an inverted pendulum is a human being ... The inverted pendulum has been employed in various devices and trying to balance an inverted pendulum presents a unique engineering problem for researchers ...

### Famous quotes containing the words pendulum and/or inverted:

The pendulum oscillates between these two terms: Suffering—that opens a window on the real and is the main condition of the artistic experience, and Boredom ... that must be considered as the most tolerable because the most durable of human evils.
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Can they never tell
What is dragging them back, and how it will end? Not at night?
Not when the strangers come? Never, throughout
The whole hideous inverted childhood? Well,
We shall find out.
Philip Larkin (1922–1986)