Design and Modeling of Soft Continuum Manipulators Using Parallel Asymmetric Combination of Fiber-Reinforced Elastomers

Abstract

Soft Continuum Arms (SCAs) have a large workspace, dexterity, and adaptability, but at the cost of complex design construction highlighted by concatenating several serial segments. In this paper, we propose a new design architecture for SCAs composed of a parallel combination of pneumatic actuators. The BR2 SCA featured in this work is asymmetric as it combines one soft bending (B) actuator and two soft rotating (R2) actuators as opposed to state of art symmetric architectures that adopt bending segments. Spatial deformation is obtained by combining the bending and rotating feature of the individual actuators. This paper also formulates an approximate forward analysis method based on Kirchhoff rod equations to predict the spatial deformation under external loads with an accuracy less than 9% of the SCAs length. In addition, the model also takes into account the ‘coupling effect’ inherent to the asymmetric parallel combination, where actuating rotating actuator attenuates the bending performance and vice versa. Consequently, this work also refines the design of the SCA that minimizes the coupling effect. A detailed performance study of the refined BR2 manipulator on a swiveling base demonstrates a larger workspace and higher dexterity when compared with state of art single section SCAs. The performance of the design is validated through different tasks like obstacle avoidance, pick and place task and whole arm grasping. These performance attributes surpass any other single segment soft module and is a potential building block for constructing customized SCAs.

Hierarchical control of soft manipulators towards unstructured interactions

“…For example, You et al (2017) collected data on a physical platform, which costs a lot. In order to expedite training, Satheeshbabu et al (2019) used a mathematical model presented in Uppalapati and Krishnan (2021) to generate virtual training data. Wu et al (2020) used a similar method to generate training data.…”

A physics-informed, vision-based method to reconstruct all deformation modes in slender bodies

“…AlBeladi et al [42] propose a least-squares type smoothing problem with a parametrized kinematic model of curvature. While the approach was successfully applied to a specific soft robot arm [21], shear and stretch were not considered, and only in-plane bending was actually experimentally demonstrated. Fu et al [43] use instead a Cosserat rod model for piece-wise reconstruction of a snake's shape.…”

“…FREEs are pneumatic slender actuators embedding in their elastomeric shell inextensible fibers which, depending on the winding pattern and upon pressurization, lead to bending, twisting or elongation. We consider a BR 2 [21] architecture (Fig. 1) whereby three parallel FREEs, one bending and two twisting (clockwise and counterclockwise), are glued together.…”

Vision-Based Shape Reconstruction of Soft Continuum Arms Using a Geometric Strain Parametrization

“…Bioinspired soft robots [1] use stretchable skins, muscles, fluids, fibers and tendons to deform in a continuum fashion. Soft Continuum Arms (SCAs) [2]- [4] are long and slender soft robots inspired by octopus arms and elephant trunks, and possess large spatial workspace and dexterity. The material elasticity combined with inherent damping enables safe and adaptable interaction with the surroundings.…”

“…A two dimensional shape was estimated by first extracting the visual markers on the Fig. 1: (above) Images of the BR 2 soft continuum arm [4] from different angles showing a configuration that involves simultaneous bending and twist. (bottom) The view from the camera used for estimating the shape.…”