Design and Characterization of a Low-Cost and Efficient Torsional Spring for ES-RSEA

The design of torsional springs for series elastic actuators (SEAs) is challenging, especially when balancing good stiffness characteristics and efficient torque robustness. This study focuses on the design of a lightweight, low-cost, and compact torsional spring for use in the energy storage-rotary...

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Bibliographic Details
Published in:Sensors (Basel, Switzerland) Switzerland), 2023-04, Vol.23 (7), p.3705
Main Authors: Al-Dahiree, Omar Sabah, Ghazilla, Raja Ariffin Raja, Tokhi, Mohammad Osman, Yap, Hwa Jen, Gul, Mustabshirha
Format: Article
Language:English
Subjects:
Actuators
Back injuries
Biomechanics
Compliance
Design
Design for manufacturability
Economic aspects
Energy storage
Exoskeletons
Force
force sensor
Gait
Hydraulic jet cutting
Injury prevention
Linearity
Load
Low cost
lumbar support
Rehabilitation
Robotics
Robots
SEA
Sensors
series elastic actuator
Springs (elastic)
Stiffness
Stroke
Topology optimization
Torque
torsion spring
Torsion springs
wearable robot exoskeleton
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Summary:The design of torsional springs for series elastic actuators (SEAs) is challenging, especially when balancing good stiffness characteristics and efficient torque robustness. This study focuses on the design of a lightweight, low-cost, and compact torsional spring for use in the energy storage-rotary series elastic actuator (ES-RSEA) of a lumbar support exoskeleton. The exoskeleton is used as an assistive device to prevent lower back injuries. The torsion spring was designed following design for manufacturability (DFM) principles, focusing on minimal space and weight. The design process involved determining the potential topology and optimizing the selected topology parameters through the finite element method (FEM) to reduce equivalent stress. The prototype was made using a waterjet cutting process with a low-cost material (AISI-4140-alloy) and tested using a custom-made test rig. The results showed that the torsion spring had a linear torque-displacement relationship with 99% linearity, and the deviation between FEM simulation and experimental measurements was less than 2%. The torsion spring has a maximum torque capacity of 45.7 Nm and a 440 Nm/rad stiffness. The proposed torsion spring is a promising option for lumbar support exoskeletons and similar applications requiring low stiffness, low weight-to-torque ratio, and cost-effectiveness.
ISSN:1424-8220
1424-8220
DOI:10.3390/s23073705