Spinal Helical Actuation Patterns for Locomotion in Soft Robots

• Published in: IEEE robotics and automation letters Vol. 5; no. 3; p. 1
• Main Authors: Case, Jennifer C., Gibert, James, Booth, Joran, SunSpiral, Vytas, Kramer-Bottiglio, Rebecca
• Format: Journal Article
• Language: English
• Published: United States IEEE 01.07.2020; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Active control; Actuation; Actuators; Biologically-Inspired Robots; Elastomers; Foot; Friction; Gait; Legged locomotion; Legged Robots; Legs; Locomotion; Modular design; Robot control; Robot dynamics; Robot sensing systems; Robots; Skin; Soft Robot Materials and Design; Soft robotics; Stiffness; Soft robot materials and design; legged robots; biologically-inspired robots
• ISSN: 2377-3766; 2377-3766
• DOI: 10.1109/LRA.2020.2982352

Spinal-driven locomotion was first hypothesized to exist in biological systems in the 1980's; however, only recently has the concept been applied to legged robots. In implementing spinal-driven locomotion in robots to-date, researchers have focused on bending in the spine. In this paper, we propose an additional mode of spinal-driven locomotion: axial torsion via helical actuation patterns. To study torsional spinal-driven locomotion, a six-legged robot with unactuated legs is used. This robot is designed to be modular to allow for changes in the physical system, such as material stiffness of the spine and legs, and has actuators that spiral around the central elastomeric spine of the robot. A model is provided to explain torsional spinal-driven locomotion. Three spinal gaits are developed to allow the robot to walk forward, through which we demonstrate that the speed of the robot can be influenced by the stiffness of the spine and legs. We also demonstrate that a single gait can be used to drive the robot forward and turn the robot left and right by adjusting the leg positions or foot friction. The results indicate that the inclusion of helical actuation patterns can assist in movement. The addition of these actuation patterns or active axial torsion to future, more complex robots with active leg control may enhance the energy efficiency of locomotion or enable fast, dynamic maneuvering.