Design of a compact gravity equilibrator with an unlimited range of motion

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A gravity equilibrator is a statically balanced system which is designed to counterbalance a mass such that any preferred position is eliminated and thereby the required operating effort to move the mass is greatly reduced. Current spring-to-mass gravity equilibrators are limited in their range of motion as a result of design limitations. An increment of the range of motion is desired to expand the field of applications. The goal of this paper is to present a compact one degree of freedom mechanical gravity equilibrator that can statically balance a rotating pendulum over an unlimited range of motion. Static balance over an unlimited range of motion is achieved by a coaxial gear train that uses non-circular gears. These gears convert the continuous rotation of the pendulum into a reciprocating rotation of the torsion bars. The pitch curves of the non-circular gears are specifically designed to balance a rotating pendulum. The gear train design and the method to calculate the parameters and the pitch curves of the non-circular gears are presented.

A prototype is designed and built to validate that the presented method can balance a pendulum over an unlimited range of motion. Experimental results show a work reduction of 87 % compared to an unbalanced pendulum and the hysteresis in the mechanism is 36 %.
Original languageEnglish
Title of host publicationProceedings of the 40th Mechanisms and Robotics Conference
Subtitle of host publicationASME 2016 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference
Place of PublicationNew York, NY, USA
ISBN (Print)978-0-7918-5015-2
Publication statusPublished - 2016
Event40th Mechanisms and Robotics Conference - Charlotte, North Carolina, United States
Duration: 21 Aug 201624 Aug 2016

Publication series

NameASME Conference Proceedings


Conference40th Mechanisms and Robotics Conference
CountryUnited States
CityCharlotte, North Carolina

Bibliographical note

Paper No. DETC2016-59549


  • Gravity (Force)
  • Design


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