OmniFiber: Integrated Fluidic Fiber Actuators for Weaving Movement based Interactions into the ‘Fabric of Everyday Life’

Ozgun Kilic Afsar

By Ozgun Kilic Afsar, Ali Shtarbanov, Hila Mor,  Ken Nakagaki, Jack Forman, Karen Modrei, Dr. Seung Hee Jeong, Prof. Klas Hjort, Prof. Kristina Hook, Prof. Hiroshi Ishii

By Ozgun Kilic Afsar, Ali Shtarbanov, Hila Mor,  Ken Nakagaki, Jack Forman, Karen Modrei, Dr. Seung Hee Jeong, Prof. Klas Hjort, Prof. Kristina Hook, Prof. Hiroshi Ishii

OmniFiber is a reconfigurable material system for movement-based interaction design, based on thin fluidic fiber actuators with closed-loop strain control. We explore how I/O capabilities and multimodal haptic feedback of thin fluidic fibers can be leveraged to develop novel tangible interactions. We explore how thinness and sensory capability of artificial muscle-based devices can be utilized to develop novel user interaction, for example to augment users’ natural muscles to record and replay movements and rendering dynamic linear curved shapes for display and affordance.

Project Description

Concept of OmniFiber

Thin linear forms are a humble yet ubiquitous geometric building blocks found throughout nature and the human body. For example, human skeletal muscle tissues, which help navigate our locomotion and consciously controlled movements, are a bundle of muscle fiber modules that compose 30% of our body weight. Such primitive artificial muscle fibers resembling those in the human body have been explored in the field of robotics as flexible exoskeletons to assist body movements. In this work, we utilize such thin and flexible fiber form factor as a configurable building-block to create dynamic movement-based interactions.

OmniFiber is a novel method in designing interactions with dynamic motion using a fiber form factor based on thin fluid-actuated artificial muscle fibers. The design system is based on thin McKibben muscles that consist of filaments wrapped around elastomeric chambers surrounded by a woven sleeve that mechanically alters the actuation behavior. Our actuators are thin (ø=600μm to 1.6mm) and flexible enough improving conformability of artificial muscles for wearables, while having fast response time (> 100 Hz), and high force output (F→ 15N). 

Design Space and Functionality

The design space of OmniFibers can be divided into two: primitive fiber architecture and fiber compositions.

The multi-layer design of OmniFiber constitutes a braided soft outer shell, sensor-patterned inner tubing, internal working fluid, and a mechanical constraint to program the overall motion. Each fiber has an integrated soft sensor allowing them to capture deformation and movements in real time to provide haptic and visual feedback.

Any application may require different types OmniFibers which mainly consists of the same materials and elements. The contractible-type fiber is typically more useful for high force output applications such as movement assistance and rehab, whereas the extensible-type renders larger geometric deformation for applications such as soft wearable displays and robotic crafting applications.

With our mechanical programming pipeline and designated web-based design tool, we demonstrate more complex morphing behaviors (e.g. bending, coiling) with OmniFibers beyond simple axial motions such as extension and contraction demonstrated by previous fluidic artificial muscle research.

We present two selective strain-limiting techniques to mechanically program the shape-changing behaviour via; 1) an inlaid thread technique to manipulate the mechanical behaviour of the braided shell,  2) 3D-printed flexible constraint that can be relocated to change the strain-limiting section as can be seen in the video below.

One core feature of our design system is modularity. This feature enables the user to customize the scale, assembly and configuration of the closed-loop controlled fibers for a given application. For example, if an application requires higher force outputs, the fibers can be simply arrayed, bundled or woven in a fabric form.

System Overview

The overall design of our system consists of the following components: a flexible and stretchable fiber-based modular interface, a pneumatic development platform FlowIO, with web-based GUI, and a multi-channel, multiplexed analog input for closed-loop strain control. 

Our system is also modular at the control level, using the FlowIO Platform by Ali Shtarbanov, a miniaturized integrated development platform for driving soft pneumatically-actuated devices. 

We appropriated the FlowIO design to fit the following requirements of our system; yielding high pressure (0-350kPa) applications and BLE communication with the multichannel resistive circuit allowing closed-loop control, and additional features for tangible programmability.

Application Space

In our demonstrations, we explored how OmniFiber-based devices can be utilized to develop novel user interactions; for example augmenting users’ natural muscles when playing an instrument, or recording and replaying the respiratory physiology of a classically trained singer.

We also implemented dynamic line-based interfaces for display and affordance such as interactive cables, soft on-body displays for sending visuo-haptic messages to a loved one, and robotic jewelry that adapts to its owner's body movements.