2005/12/14 by Frank Borg, Borg, Frank
Physics and Astronomy · #Biological Physics (physics.bio-ph) #Experimental and Theoretical Physics Studies #FOS: Physical sciences #Physics Education (physics.ed-ph) #physics.bio-ph #physics.ed-ph
paper · pdf · doi:10.48550/arxiv.physics/0512122
22 pages, 6 figures
arxiv created 2005/12/14 · openalex publication_date 2005/12/14 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
The normal and the inverted pendulum continue to be one of the main physical models and metaphors in science. The inverted pendulum is also a classic study case in control theory. In this paper we consider a special demonstration version of the inverted pendulum which is controlled via a spring. If the spring constant is below a critical level the springy control will be unstable and the pendulum will be kept from falling only by exercising a dynamically varying control. This situation resembles the case of human bipedal quiet standing with the Achilles tendon serving as the spring. The paper is written with physics students in mind.