Coaxial negative torsion stiffness mechanism developed for compact gravity compensation

Master thesis (2020)

Authors

D.M. Mulder Mechanical Engineering

Contributors

J. Rommers Mechatronic Systems Design - Mechanical, Maritime and Materials Engineering (mentor)
J.L. Herder Precision and Microsystems Engineering (mentor)
T. Horeman Medical Instruments & Bio-Inspired Technology - Mechanical, Maritime and Materials Engineering (graduation committee member)
Faculty
Mechanical Engineering, Mechanical Engineering
Copyright: © 2020 Dies Mulder
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Published Date

28-09-2020

Language

English

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Faculty

Mechanical Engineering

Abstract

The mechanism presented in this paper generates a partially negative stiffness characteristic, which is suitable for the balancing of a pendulum in a gravity field. The mechanism uses deformation in the axial direction of the base joint to store potential energy. The proposed design is located next to the base joint of the pendulum in an area rarely used by other balancing mechanisms. Utilising this space makes it an attractive alternative when space in the plane of motion is restricted. The mechanism consists of two linear springs and a non-linear transmission that form a compact system which can be manufactured out of tubes. The balancing curve that is generated by the mechanism has a theoretical maximum error of < 0:05% between ±22:5° around the horizontal position. The difference between the test results and the theory ranged from 0.4 % and 1.7 %. This gravity balancing mechanism is interesting when the mechanism should be located beside the base joint and or when low hysteresis and low error are required.