UC Santa Barbara

Soft robotics technologies hold substantial promise for use in wearable haptic systems, due to their ability to supply forces to the human body in a compliant, conformal, and safe manner. While existing research at the intersection of soft robotics and wearable haptics focuses on "attaching" soft actuators onto the body, it remains a challenge to seamlessly integrate soft actuators into garments in a compact, safe, and effective way. The overarching goal of my PhD research is to transform textiles into soft robotic haptic garments that are comfortable, ergonomic, and can provide multimodal, affective, and expressive haptic feedback tailored to the human sense of touch. This PhD research integrates research on the design, fabrication, and control methods for soft robotic textiles. This dissertation contributes new methods for expressive haptic feedback for large areas of the body, and guidelines for the design of haptic feedback delivered via garments, accounting for immersion, emotion, affect, and health-related benefits. At a broader lever, this dissertation contributes to the fidelity, ubiquity, and social relevance of wearable haptic systems, by allowing haptics to be seamlessly integrated within garments that are widely used.

The first chapter of this dissertation gives an introduction of my PhD research and outlines the main contributions. After the introduction, the second chapter reviews emerging advances in soft wearable robotic and haptic technologies, and several promising application areas, including wearable haptic interfaces, assistive robotics, and biomedical devices [1]. It summarizes essential design considerations for such systems based on functional concerns, wearability, and ergonomics. It provides a synthetic review of design strategies that have been adopted in numerous examples from prior research by surveying sensing and actuation technologies, materials, and fabrication methods. The chapter concludes with a discussion of frontiers, challenges, and future prospects for soft, wearable robotics. These findings guided the development of novel wearable technologies and haptic rendering methods in the following chapters of the dissertation.

The third chapter of this dissertation presents the development of a new family of soft actuators that are suitable, versatile, and effective for wearable applications. We refer to these actuators as fluidic fabric muscle sheets (FFMS) [2]. These sheet-like actuators can strain, squeeze, bend, and conform to the human body. I designed and fabricated FFMS using fabrics and elastic tubes through facile apparel engineering methods. Though the fabrication process is low-cost and straightforward, FFMS can operate at frequencies of 5 Hz or more, achieve engineering strains exceeding 100%, and exert forces exceeding their weight by more than 10,000%. I further demonstrated several potential use cases of FFMS actuators, including a miniature steerable robot, a glove for grasp assistance, garments for applying compression to the extremities, and devices for actuating small body regions or tissues via localized skin stretch.

The fourth chapter of this dissertation demonstrates how FFMS actuators can be used to realize a wearable haptic interface with integrated sensing and multimodal actuation. Using six FFMS actuators, I constructed a forearm sleeve called the PneuSleeve [3]. It is able to render a broad range of haptic feedback types including compression, skin stretch, and vibration, and is able to supply consistent feedback to users with different arm sizes and anatomies by virtue of integrated soft capacitive sensors and a closed-loop force controller. Physical characterizations showed that the actuators generated consistent and perceivable forces at frequencies of 20 Hz, as validated in engineering characterizations. Results of user studies highlight the expressiveness of the haptic effects it provides. The PneuSleeve holds the potential for enabling new interfaces, haptic notifications, navigation, gaming, AR/VR experiences, and many other applications.

In the fifth chapter of this dissertation, informed by the preceding results, I designed and investigated a peristaltic wearable robot for supplying dynamic compression therapy via finger-sized FFMS actuators. The wearable robot can produce dynamic compression pressure exceeding 22 kPa at frequencies of 14 Hz or more, meeting the requirements for compression therapy and massage. An array of software-programmable peristaltic compression patterns can be furnished by varying frequency, amplitude, phase delay, and duration parameters. To evaluate the promise this wearable robot holds for aiding peripheral hemodynamic flow, I designed a mechanical fixture integrating artificial muscles, skin, and a vein, modeled after the human upper limb. Results showed that the wearable robot was capable of driving fluid flow at rates of up to 1 mL/min. The results matched theoretically derived predictions for peristaltic fluid transport. This dynamic compression garment holds promise for treating disorders affecting lymphatic and blood circulation.