Single motor actuated peristaltic wave generator for a soft bodied worm robot

Abstract

This paper presents the design and development of a single motor actuated peristaltic worm robot with three segments using a bio-inspired method of locomotion with one actuator that achieves optimised worm like peristaltic motion. Each segment consists of two solid circular disks that have a tendon connected through to the drive mechanism using a Bowden cable and a soft rubber skin that deforms under the compression of the tendon. Our hypothesis that a tuned peristaltic waveform can achieve improved performance of locomotion distance and clamping strength is proven using an initial test platform capable of demonstrating varying waveform types with multiple actuators. Three experiments were undertaken: (i) moving along a flat surface, (ii) moving through a confined tunnel (iii) moving through a confined tunnel whilst pulling a payload. Results from these experiments have identified the optimal parameters for a smart gearbox capable of achieving the same optimal peristaltic waveform signal as the more complex test platform but with only one actuator driving all three worm segments. Unlike other examples of peristaltic worm robots, this example uses a control method embedded within the mechanics of the design removing excessive number of actuators which contributes to miniaturisation, reduces power consumption and simplifies the overall design.

Worm-Like Soft Robot for Complicated Tubular Environments

“…The robot can move forward in tubular environments by repeating the Phase (1)*Phase (6). In case of moving backward, the motion is reversed as Phase (6)*Phase (1).…”

“…It is obviously impractical to use a traditional industrial robot arm or pipe endoscope since long, complicated, and multibranch pipelines require a higher degree of freedom (DoF). Although some flexible in-pipe robots with different locomotion mechanisms such as the wheel type, 1,2 walking type, 3,4 worm-like type, [5][6][7] screw type, 8 and snake type 9 have been proposed, most are developed using rigid structures. Such structures have difficulty entering complex narrow pipelines, and are not suitable for slippery or compliant environments.…”

Non-Conventional Deformations: Materials and Actuation

“…Electricity is relatively easily controllable independently of environmental conditions and can be exploited to actuate non-conventional deformation in various ways. It can power electromotors [9][10][11][12][13] as well as piezo- [14][15][16][17][18][19] and other electrosensitive materials. Due to this diversity, there is an extensive literature on electro-actuated systems.…”

“…Another way to increase efficiency is to decrease the number of actuators (motors) needed for complex morphing. Winstone et al [13] proposed a design of a single-motor-driven worm robot that was capable of peristaltic locomotion thanks to the design of its segments enabling complex motions to simple impulsions.…”

“…Materials 2020,13, x FOR PEER REVIEW 9 of 26 due to its high energy density contraction in response to applied heat. Shaw et al [44] even demonstrated that NiTi honeycomb structures exhibit not only significant shape memory behavior but a high level of superelasticity as well, when loaded in-plane.…”