Master of Science, Miami University, 2023, Mechanical Engineering

Available devices with smaller touchscreen displays (TSDs) offer users adequate haptic feedback, whereas larger TSDs still lack meaningful tactile sensations. This study is focused on rendering vibrotactile feedback on large TSDs. Existing methods for localized vibrotactile rendering on large TSDs use many actuators. Practically, using many actuators is not desirable due to space constraints, power supply limitations, etc., for consumer-centric large TSD devices. Therefore, this study investigates localized vibrotactile feedback on large TSDs using a restricted number of electrostatic resonant actuators (ERAs). Using flexible boundary conditions combined with multi-frequency excitation, a novel method is presented to render localized vibrotactile feedback for two types of large TSDs: a narrow touch bar and a rectangular touch surface. A method for managing/positioning localized haptic feedback on large TSDs is also investigated. In-house finite-element-based simulation models of TSDs are developed along with experimental prototypes for verifying the vibrotactile performance. The modeling and analysis strategy presented here is general and can be extended for haptic rendering methods of different touch surfaces, actuators, and boundary conditions. Finally, model-based parametric studies are presented for better design considerations and improved vibrotactile intensity.

Committee: Kumar Singh (Advisor); Jeong-Hoi Koo (Advisor); James Chagdes (Committee Member) Subjects: Electrical Engineering; Engineering; Mechanical Engineering

Master of Science, Miami University, 2021, Mechanical and Manufacturing Engineering

Vibrotactile feedback is a key feature of many small touchscreen devices, but is often absent or incomplete in large touchscreen displays due to a lack of suitable actuators for such applications. Thus, a growing need exists for haptic actuators capable of producing meaningful feedback in large touch displays. This study proposes and evaluates a dual-electrode electrostatic resonant actuator (ERA) as a means to fulfill such a need. The dual-electrode ERA was compared to a similar singleelectrode ERA to study the effect of electrode configuration. It produced a maximum vibration 73% higher than the single-electrode actuator, showing promising potential for its use in large touchscreen applications. To study the ERA in a large display application, a prototype touch bar system with spring boundaries was designed, fabricated, and evaluated. By varying the number of actuators excited in the system, the actuators' magnitude, excitation frequency, and signal duration, a maximum vibration of 4 g-forces could be achieved throughout the majority of the display in both sustained and pulse sensations. This demonstrates a promising potential for generating a freely positionable and fully controllable point of vibrotactile stimulation at any point of a touch bar display. These results show the feasibility of the actuator spring boundary implementation and the dual-electrode ERA for large touchscreen display applications.

Committee: Jeong-Hoi Koo (Advisor); Tae-Heon Yang (Committee Member); James Chagdes (Committee Member) Subjects: Mechanical Engineering

MA, University of Cincinnati, 2021, Arts and Sciences: Psychology

Upper-limb protheses are subject to high rates of abandonment. Prosthesis abandonment is related to a reduced sense of embodiment, the sense of self-location, agency, and ownership that humans feel in relation to their bodies and body parts. If a prosthesis does not evoke a sense of embodiment, users are less likely to view them as useful and integrated with their bodies. Currently, visual feedback is the only option for most prosthesis users to account for their augmented activities. However, for activities of daily living, such as grasping actions, haptic feedback is critically important and may improve sense of embodiment. Therefore, we are investigating how converting natural haptic feedback from the prosthetic fingertips into vibrotactile feedback administered to another location on the body may allow participants to experience haptic feedback and if and how this experience affects embodiment. While we found no differences between our experimental manipulations of feedback type, we found evidence that embodiment was not negatively impacted when switching from natural feedback to proximal vibrotactile feedback. Proximal vibrotactile feedback should be further studied and considered when designing prostheses.

Committee: Tamara Lorenz Ph.D. (Committee Chair); Kevin Shockley Ph.D. (Committee Chair); Paula Silva Ph.D. (Committee Member) Subjects: Psychology

Master of Science, Miami University, 2019, Mechanical and Manufacturing Engineering

Realistic haptic feedback is necessary to provide meaningful touch information to users of numerous technologies, such as virtual reality, mobile devices and robotics. For a device to convey realistic haptic feedback, two touch sensations must be present: tactile feedback and kinesthetic feedback. Tactile feedback is felt at the surface of one's skin and displays textures and vibrations, whereas kinesthetic feedback is felt in one's joints and muscles and transmits position and movement information. While many devices today display tactile feedback through vibrations, most neglect to incorporate kinesthetic feedback due to size constraints. To provide comprehensive feedback, this study investigates a new haptic device based on an unconventional actuation method: electrorheological (ER) fluid, a smart fluid with tunable yield stress under the application of electric field. The device's control electronics and structural components are integrated into a compact printed circuit board, resulting in a slim device suitable for mobile applications. By controlling the ER fluid flow via applied electric fields, the device can generate a wide and distinct range of both tactile and kinesthetic sensations. These sensations were derived analytically from ER fluid's governing equations as well as experimentally. The device may be used as a haptic interface between a user and virtual environment.

Committee: Jeong-Hoi Koo Ph.D. (Advisor); Tae-Heon Yang Ph.D. (Committee Member); Michael Bailey Van Kuren Ph.D. (Committee Member) Subjects: Computer Engineering; Materials Science; Mechanical Engineering

Master of Science in Industrial and Human Factors Engineering (MSIHE) , Wright State University, 2015, Industrial and Human Factors Engineering

Vibrotactile feedback, used as sensory substitution for loss of haptic feedback, has been utilized to improve performance in manual control, teleoperation and during minimally invasive surgical tasks. Stochastic resonance (SR), introduced into the human control system as white noise at a sub-threshold level, has shown promise to improve the sensitivity of tactile receptors resulting in enhancement of performance for a variety of manual tracking and sensorimotor tasks. The purpose of this study was to determine if SR could improve performance (accuracy, speed) in a simulated laparoscopic palpation task and to compare it to vibrotactile feedback (VIB). It was hypothesized that both VIB and SR feedback would result in better performance over no feedback (Control). Furthermore, SR feedback was expected to lead to the greatest increase in performance by improving subjects' haptic sensitivity to tissue compliance and consistency. A total of 16 subjects (10 female, 6 male) performed a palpation task using laparoscopic tools to detect the presence of tumors (compacted felt) embedded in simulated tissue samples (silicone gel) in a laparoscopic trainer box. Subjects were randomly assigned to one of three different conditions: (1) Control and SR, (2) Control and VIB, (3) Control and VIB+SR and (4) Control and Control. The control condition was performed before the vibration condition to set a baseline for performance as well as to account for carry-over effects related to vibrotactilefeedback and human performance. The vibrotactile feedback and SR vibrations were administered via two different haptic actuators attached to subjects' dominant upper and lower arms, respectively. Each subject was presented 36 tissue samples (24 w/tumor, 12 non-tumor) in random order, under the control condition and then presented the same 36 samples in a different random order under the assigned vibration condition (SR, VIB, VIB+SR, Control), for a total of 72 tissue samples (48 w/tumor, 24 (open full item for complete abstract)

Committee: Carolin Cao Ph.D. (Committee Chair); Chandler Phillips M.D. (Committee Member); Joseph Slater Ph.D. (Committee Member) Subjects: Biomedical Engineering; Engineering; Health Care; Medicine; Neurobiology; Surgery