Passive Gravity Balancing with a Self-Regulating Mechanism for Variable Payload

Diego Franchetti,Basilio Lenzo,Giovanni Boschetti

doi:10.3390/machines9080145

Diego Franchetti, Basilio Lenzo + Show 1 more

Open Access

https://doi.org/10.3390/machines9080145

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Journal: Machines	Publication Date: Jul 29, 2021
Citations: 3	License type: CC BY 4.0

Affiliation: Sheffield Hallam University, University of Padua

Abstract

Gravity balancing techniques allow for the reduction of energy consumptions in robotic systems. With the appropriate arrangements, often including springs, the overall potential energy of a manipulator can be made configuration-independent, achieving an indifferent equilibrium for any position. On the other hand, such arrangements lose their effectiveness when some of the system parameters change, including the mass. This paper proposes a method to accommodate different payloads for a mechanism with a single degree-of-freedom (DOF). By means of an auxiliary mechanism including a slider, pulleys and a counterweight, the attachment point of a spring is automatically regulated so as to maintain the system in indifferent equilibrium regardless of the position, even when the overall mass of the system varies. Practical implications for the design of the mechanism are also discussed. Simulation results confirm the effectiveness of the proposed approach.

Highlights

Constant force mechanisms exert forces with predetermined magnitude and direction, regardless of the mechanism configuration [1,2]
A common application of such systems in robotics is passive gravity balancing for manipulators
Passive gravity balancing is widely used in plenty of fields, including industry [3], medicine [4] and even everyday objects such as Anglepoise lamps [5,6]

Summary

Introduction

Constant force mechanisms exert forces with predetermined magnitude and direction, regardless of the mechanism configuration [1,2]. While zero-free length springs do not physically exist, there are interesting solutions to mimic such a behavior with real springs [13,14,15,16] Another practical aspect of gravity balancing is the need for auxiliary links. [30] proposes a self-regulator mechanism for a 1-DOF link that does not require manual locking/releasing interventions It requires changing the kinematics of the system, provoking a significant decrease in terms of workspace. This paper presents a self-regulating mechanism for a 1-DOF link that allows for a change in the configuration of the system in order to accommodate different payloads, without the need of recalculating relevant parameters of the balancing system and amending it .

Balancing a Single DOF Link

Remarks and Simulation Results