Elastic Actuator Design Based on Bending of Cylindrical Beam for Robotic Applications

Reis Murat,Nafiseh Ebrahimi,Amir Jafari

doi:10.3390/act9030080

Reis Murat, Nafiseh Ebrahimi + Show 1 more

Open Access

https://doi.org/10.3390/act9030080

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Abstract

The lack of suitable actuators has hampered the development of high-performance machines or robots that can compete with living organisms in terms of motion, safety, and energy efficiency. The adaptation properties of biological systems to environmental variables—for example, the control performance of biological muscle with variable stiffness properties—exceeds the performance of mechanical devices. The variable stiffness characteristics of elastic actuators are different from the operating principle of conventional solids. Although there has been a lot of work on the design of elastic actuators in recent years, a low-cost and compact elastic actuator that can be used in place of standard rigid servo actuators is not yet available. In this study, a standard servo motor has been transformed into an elastic actuator by an elastic coupling attached to the gear system. The elastic coupling consists of four small steel beams with a cylindrical cross section placed on the circular disk, and the stiffness of the actuator is adjusted by varying the clutch length of the cylindrical beams. In this study, this innovative design is explained, then the equations expressing the variation of the torsional stiffness of the cylindrical beams with the coupling length and solutions of these equations are given. The experimental results are presented to show the ability of the proposed actuator to control position and regulate the stiffness independently.

Highlights

Conventional robots use rigid actuators and rigid connections to provide movement and interact with their environment
AX-12A Robot and set our goal to bring the capability of stiffness adjustment to this actuator by adding not more than 10% of the original actuator weight and not more than 10% of the original actuator volume. This means the overall weight of the proposed stiffness adjustment mechanism should be less than 0.1 × 55 g while the overall size should remain below 125 cm3
By using the relations given in Equations (1) and (2), the angular stiffness values of the actuator can be obtained depending on the clutch length

Summary

Introduction

Conventional robots use rigid actuators and rigid connections to provide movement and interact with their environment This is necessary for production robots that require high position accuracy and operational robots used in the medical field. Mammalians can actively change the stiffness of muscle and tendon structures during locomotion In this way, they use their legs like an elastic limb to protect their body structures from these shock loads in high speed movements. They use their legs like an elastic limb to protect their body structures from these shock loads in high speed movements They store the energy of the response force from the ground in the elastic body members and, in the step, convert this potential energy into kinetic energy and require much less energy than robots for progression

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