Stanford Advisors


All Publications


  • Advancing Accessible 3D Design for the Blind and Visually-Impaired via Tactile Shape Displays Siu, A. F., ACM ASSOC COMPUTING MACHINERY. 2019: 146–49
  • shapeCAD: An Accessible 3D Modelling Workflow for the Blind and Visually-Impaired Via 2.5D Shape Displays Siu, A. F., Kim, S., Miele, J. A., Follmer, S., Assoc Comp Machinery ASSOC COMPUTING MACHINERY. 2019: 342–54
  • Making Nonvisually: Lessons from the Field Bennett, C. L., Stangl, A., Siu, A. F., Miele, J. A., Assoc Comp Machinery ASSOC COMPUTING MACHINERY. 2019: 279–85
  • Tactile Code Skimmer: A Tool to Help Blind Programmers Feel the Structure of Code Falase, O., Siu, A. F., Follmer, S., Assoc Comp Machinery ASSOC COMPUTING MACHINERY. 2019: 536–38
  • HoloNeedle: Augmented Reality Guidance System for Needle Placement Investigating the Advantages of Three-Dimensional Needle Shape Reconstruction IEEE ROBOTICS AND AUTOMATION LETTERS Lin, M. A., Siu, A. F., Bae, J., Cutkosky, M. R., Daniel, B. L. 2018; 3 (4): 4156–62
  • Investigating Tangible Collaboration for Design Towards Augmented Physical Telepresence DESIGN THINKING RESEARCH: MAKING DISTINCTIONS: COLLABORATION VERSUS COOPERATION Siu, A. F., Yuan, S., Pham, H., Gonzalez, E., Kim, L. H., Le Goc, M., Follmer, S., Plattner, H., Meinel, C., Leifer, L. 2018: 131–45
  • An Accessible CAD Workflow Using Programming of 3D Models and Preview Rendering in A 2.5D Shape Display Siu, A. F., Miele, J., Follmer, S., Assoc Comp Machinery ASSOC COMPUTING MACHINERY. 2018: 343–45
  • Rendered and Characterized Closed-Loop Accuracy of Impedance-Type Haptic Displays IEEE TRANSACTIONS ON HAPTICS Colonnese, N., Siu, A. F., Abbott, C. M., Okamura, A. M. 2015; 8 (4): 434-446

    Abstract

    Impedance-type kinesthetic haptic displays aim to render arbitrary desired dynamics to a human operator using force feedback. To render realistic virtual environments, the difference between desired and rendered dynamics must be small. In this paper, we analyze the closed-loop dynamics of haptic displays for three common virtual environments: a spring, a damper, and a spring-damper, including the effects of time delay and low-pass filtering. Using a linear model, we identify important parameters for the rendered dynamics in terms of effective impedances, a conceptual tool that decomposes the displays closed-loop impedance into components with physical analogs. Our results establish bandwidth limits for rendering effective stiffness and damping. The effective stiffness bandwidth is limited by the virtual stiffness and device mass, and the effective damping bandwidth is limited by the cut-off frequency of the low-pass filter which filters the device velocity estimate. We show that a general system impedance can be characterized by a mass, damper, and spring optimally by the solution to a convex optimization problem, and we present a quantitative metric, the Average Distortion Error (ADE), to describe the fidelity of this model. Time delay has no significant effect on characterized stiffness, and reduces characterized damping by the product of virtual stiffness and total time delay. Reducing the low-pass filter cut-off frequency reduces the characterized damping. Experimental data gathered with a Phantom Premium 1.5 validates the theoretical analysis. We also conducted human user experiments to investigate the effects of time delay and low-pass filtering on perceived stiffness and damping. Similar to the characterized dynamics results, we observed no significant effect of time delay on perceived stiffness, and increasing time delay resulted in reduced perceived damping. Lower filter cut-off frequencies resulted in lower perceived damping. This work informs haptic display design by presenting how closed-loop behavior changes with key parameters.

    View details for DOI 10.1109/TOH.2015.2457438

    View details for Web of Science ID 000369611500008

    View details for PubMedID 26208363

  • Disposable platform provides visual and color-based point-of-care anemia self-testing JOURNAL OF CLINICAL INVESTIGATION Tyburski, E. A., Gillespie, S. E., Stoy, W. A., Mannino, R. G., Weiss, A. J., Siu, A. F., Bulloch, R. H., Thota, K., Cardenas, A., Session, W., Khoury, H. J., O'Connor, S., Bunting, S. T., Boudreaux, J., Forest, C. R., Gaddh, M., Leong, T., Lyon, L. A., Lam, W. A. 2014; 124 (10): 4387-4394

    Abstract

    Anemia, or low blood hemoglobin (Hgb) levels, afflicts 2 billion people worldwide. Currently, Hgb levels are typically measured from blood samples using hematology analyzers, which are housed in hospitals, clinics, or commercial laboratories and require skilled technicians to operate. A reliable, inexpensive point-of-care (POC) Hgb test would enable cost-effective anemia screening and chronically anemic patients to self-monitor their disease. We present a rapid, stand-alone, and disposable POC anemia test that, via a single drop of blood, outputs color-based visual results that correlate with Hgb levels.We tested blood from 238 pediatric and adult patients with anemia of varying degrees and etiologies and compared hematology analyzer Hgb levels with POC Hgb levels, which were estimated via visual interpretation using a color scale and an optional smartphone app for automated analysis.POC Hgb levels correlated with hematology analyzer Hgb levels (r = 0.864 and r = 0.856 for visual interpretation and smartphone app, respectively), and both POC test methods yielded comparable sensitivity and specificity for detecting any anemia (n = 178) (<11 g/dl) (sensitivity: 90.2% and 91.1%, specificity: 83.7% and 79.2%, respectively) and severe anemia (n = 10) (<7 g/dl) (sensitivity: 90.0% and 100%, specificity: 94.6% and 93.9%, respectively).These results demonstrate the feasibility of this POC color-based diagnostic test for self-screening/self-monitoring of anemia.Not applicable.This work was funded by the FDA-funded Atlantic Pediatric Device Consortium, the Georgia Research Alliance, Children's Healthcare of Atlanta, the Georgia Center of Innovation for Manufacturing, and the InVenture Prize and Ideas to Serve competitions at the Georgia Institute of Technology.

    View details for DOI 10.1172/JCI76666

    View details for Web of Science ID 000342649900034

    View details for PubMedID 25157824