Recipient Organization
UNIV OF MINNESOTA
(N/A)
ST PAUL,MN 55108
Performing Department
Design, Housing & Apparel
Non Technical Summary
Garment-based wearable technology offers significant potential to improve the health and wellness of their wearers, which is especially promising for rural communities in Minnesota with aging populations and limited healthcare access. Recent advances in textile-based sensors and actuators provide a roadmap to develop new garment-integrated technologies that are both functional and perceptually invisible in everyday clothing. This project seeks to investigate a novel form of stitch-based soft robotic structures, using shape memory alloys constructed into coverstitches and chain-stitches, that can be manufactured in seconds using typical softgoods machinery and which can be non-invasively integrated into clothing without negatively impacting its typical properties. The approach proposed herein leverages existing expertise and infrastructure of the UMN Wearable Technology Laboratory (WTL), which has previously pioneered this approach to produce soft, stitch-based sensor technologies. We seek to extend this approach to soft, stitch-based actuators, and will study these structures at the stitch, textile, and garment level, culminating in human subject testing to assess the functional and usability properties of soft robotic everyday clothing. If successful, this project will offer new engineering and design strategies for creating physically dynamic, everyday clothing.
Animal Health Component
50%
Research Effort Categories
Basic
50%
Applied
50%
Developmental
(N/A)
Goals / Objectives
The following three specific aims / research objectives are proposed:Year 1: Assess the functionality and manufacturability of cover-stitch and chain-stitch structures comprised of commercially-available SMA actuator wire.Year 2: Design and manufacture a series of everyday garments with embedded SMA cover-stitches and chain-stitches designed to provide dynamic/togglable stiffness properties to provide mechanical support to the wearer.Year 3: Pilot test these garments on human subjects in both the laboratory and in naturalistic work environments to assess their effectiveness at providing useful robotic support in typical labor/tasks (e.g., providing dynamic lateral support at the knee during squatting/knee bending tasks, providing dynamic compressive lower back support during strenuous lifting activities, and/or providing dynamic postural support while in a seated posture).
Project Methods
This study will proceed over a three-year period, with each year crafted around the three specific aims / objectives, and will be implemented by a CDES graduate student with supervision from the project PI. SMA actuator materials will be sourced from trusted industry partners (e.g., Flexinol from Dynalloy, Inc., and/or Actuator Wire from Fort Wayne Metals), each of which have provided the WTL with SMA material for previous research products. Coverstitch and chainstitch structures will be produced using in-house equipment located in the WTL (as previously mentioned, the lab has extensive expertise in modifying these machines to accept non-standard/metallic wires to form the stitch structures, a method optimized for Dunne et al.'s coverstitch stretch sensor technology). The first year of the investigation will focus on manufacturing and characterizing SMA-based chainstitch and coverstitch structures, to evaluate performance impacts of different SMA materials, stitch densities/tensions, and fabric substrate properties. These structures will be mechanically evaluated using WTL's extensive tensile test infrastructure- characterizing both axial and bend behavior of the SMA stitch structures at varying displacements and temperatures. The second year of the project will leverage the findings of the year-1 efforts to pursue the design, manufacture, and assembly of multiple garments with embedded, optimized stitched actuators. The WTL has extensive experience in softgoods design, manufacture, and assembly: this expertise will be leveraged to create and test two soft robotic garment concepts (with specific system designs/capabilities being informed by data collected in phase 1):Selectively-stiffening, tight fitting leggings. This garment will be constructed with vertically-oriented SMA robotic stitches designed to stiffen when heated/powered to provide lateral bracing/support of the knee.Selectively-stiffening t-shirts with both laterally-oriented SMA stitches to provide selective stiffening/bracing of the lower back, and vertically-oriented SMA stitches to provide selective bending resistance/postural support.The performance and durability of these garments will be characterized in both 2D and 3D: specific metrics of interest will include (1) axial fabric stiffness (measured as force vs. displacement vs. power/temperature of the robotic stitch using an Instron tensile testing machine); fabric bending stiffness (measured using ASTM D1388-18 Standard Test Method for Stiffness of Fabrics - Cantilever Test for varying power/temperature ranges of the robotic stitch); and (3) custom benchtop testing to quantify support properties of the stiffened textiles (e.g., ability to maintain stable orientation/form of flexible and soft substrates when wrapped around a fluid-filled elastomer hose/tube). Durability testing (e.g., impact of successive wash/dry cycles on the above performance metrics) will be pursued using the WTL's in-house washing and drying machines to evaluate the impacts of repeated laundering on system performance over time. Iterative development of actuated garments may be pursued if initial performance and/or durability data warrants revision (e.g., number and orientation of robotic stitch structures could be successively varied in the active garments to increase axial and bending stiffness if necessary; and surface treatments such as adding a protective elastic tape layer atop the stitches may be pursued to reduce impacts of wash-dry cycles, if necessary). The third and final year of the project will focus on pilot human subject testing of the prototype garments in laboratory and naturalistic settings. For both the lower body and upper body robotic garments, using the WTL motion capture environment, human subjects will be asked to perform a variety of typical, manual-labor style everyday tasks (standing, sitting, walking, crouching, lifting, carrying, etc.) while wearing the robotic garments in both the deactivated and activated states (with the order of conditions randomized between subjects). Each task will be repeated 10 times by each subject, and both objective measures (e.g., time taken to complete tasks, heart / breathing rate data) and subjective user experience data (e.g., the NASA TLX subjective workload assessment as well as open-ended interviews to understand the experience) will be collected (subjects will be unblinded after completing the TLX questionnaires, to allow them to speak knowledgably about the experience of wearing the garments in their activated states). A similar set of tests will be performed outside of the lab (e.g., at a gym or other manual labor workplace where physical activity is commonly encountered by each subject) to understand if the laboratory findings of user experience are replicable in uncontrolled settings and to explore qualitative issues with use or enjoyment of using these systems in everyday, social contexts.