Programmable Telescopic Soft Pneumatic Actuators for Deployable and Shape Morphing Soft Robots

TL;DR

This work tackles the challenge of tractable design for soft robots with large length changes by introducing Programmable Soft Telescopic Actuators (PTSPAs) and a parameterised design framework that builds 3D actuators from a 1D midline, a 2D cross-section, and a 3D loft. By mapping high-level design inputs to geometry via a NURBS-based midline, union-of-circles cross-sections, and CadQuery lofts, the approach enables both axisymmetric and curvature-programmed actuation, and a semi-automated design exploration to relate geometry to performance. Key findings include up to 650% extension using a three-layer extension design, curvature programming through cross-section control, vacuum-based two-way actuation with radial stiffening, and deployment in a soft quadruped named Turtle-Roo capable of navigating confined spaces without external sensing. Collectively, these results establish PTSPAs as a versatile, modular platform for deployable and shape-morphing soft robots with multimodal locomotion capabilities and embodied adaptability.

Abstract

Soft Robotics presents a rich canvas for free-form and continuum devices capable of exerting forces in any direction and transforming between arbitrary configurations. However, there is no current way to tractably and directly exploit the design freedom due to the curse of dimensionality. Parameterisable sets of designs offer a pathway towards tractable, modular soft robotics that appropriately harness the behavioural freeform of soft structures to create rich embodied behaviours. In this work, we present a parametrised class of soft actuators, Programmable Telescopic Soft Pneumatic Actuators (PTSPAs). PTSPAs expand axially on inflation for deployable structures and manipulation in challenging confined spaces. We introduce a parametric geometry generator to customise actuator models from high-level inputs, and explore the new design space through semi-automated experimentation and systematic exploration of key parameters. Using it we characterise the actuators' extension/bending, expansion, and stiffness and reveal clear relationships between key design parameters and performance. Finally we demonstrate the application of the actuators in a deployable soft quadruped whose legs deploy to walk, enabling automatic adaptation to confined spaces. PTSPAs present new design paradigm for deployable and shape morphing structures and wherever large length changes are required.

Figures (10)

• Figure 1: Programmable Soft Telescopic Actuator Overview: a) 2D curve produced by parametric actuator generator which is revolved to produce the 3D actuators. b) Resulting 3D Printed linear actuator at rest and inflated. c) Application of bending optimised actuators in soft quadruped. The actuators inflate with positive pressure, retain their shape at atmosphere and retract under vacuum
• Figure 2: A: Visualisation of the NURBS segments and their union to construct the midline. B: Visualisation of the thickness offset applied to construct 2D cross-section. C: Visualisation of 3D construction via angular cross-sections. Shaded cross-sections are user-defined; dotted cross-sections are interpolated by the design framework $\theta_i = 30$.
• Figure 3: Geometric response of 1D input parameters.
• Figure 4: Visualisation of the geometric impacts of 2D input parameters
• Figure 5: A) Automated experimental testing apparatus containing motorised linear rail, pneumatics infrastructure, and computer vision cameras. B) Automated data extraction through computer vision processing