Haptic Edge Detection Through Shear

Most tactile sensors are based on the assumption that touch depends on measuring pressure. However, the pressure distribution at the surface of a tactile sensor cannot be acquired directly and must be inferred from the deformation field induced by the touched object in the sensor medium. Currently, there is no consensus as to which components of strain are most informative for tactile sensing. Here, we propose that shape-related tactile information is more suitably recovered from shear strain than normal strain. Based on a contact mechanics analysis, we demonstrate that the elastic behavior of a haptic probe provides a robust edge detection mechanism when shear strain is sensed. We used a jamming-based robot gripper as a tactile sensor to empirically validate that shear strain processing gives accurate edge information that is invariant to changes in pressure, as predicted by the contact mechanics study. This result has implications for the design of effective tactile sensors as well as for the understanding of the early somatosensory processing in mammals

Perception Threshold for Pressure by a Soft Textile Actuator

Electroactive textile (EAT) has the potential to apply pressure stimuli to the skin, e.g. in the form of a squeeze on the arm. To present a perceivable haptic sensation we need to know the perception threshold for such stimuli. We designed a set-up based on motorized ribbons around the arm with five different widths (range 3 - 49 mm) for psychophysical studies. We investigated the perception threshold of force pressure and ribbon reduction in two studies, using two methods (PSI and 1up/3down staircase), comparing sex, the left and right arm, the lower and upper arm, and stimulated surface area with a total of 57 participants. We found that larger stimulation surfaces require less pressure to reach the perception threshold (0.151 N per cm&lt;inline-formula&gt;&lt;tex-math notation="LaTeX"&gt;$^{2}$&lt;/tex-math&gt;&lt;/inline-formula&gt; for 3 mm width, 0.00972 N per cm&lt;inline-formula&gt;&lt;tex-math notation="LaTeX"&gt;$^{2}$&lt;/tex-math&gt;&lt;/inline-formula&gt; for 49 mm width on the lower arm). This indicates a spatial summation effect for these pressure stimuli. We did not find significant differences in perception threshold for the left and right arm and, the upper and lower arm. Between male and female participants we found significant differences for two conditions (10 mm and 25 mm) in Experiment 1, but we could not reproduce this in Experiment 2.</p

Unmediated Interaction: Communicating with Computers and Embedded Devices as If They Are Not There

Although computers are smaller and more readily accessible today than they have ever been, I believe that we have barely scratched the surface of what computers can become. When we use computing devices today, we end up spending a lot of our time navigating to particular functions or commands to use devices their way rather than executing those commands immediately. In this dissertation, I explore what I call unmediated interaction, the notion of people using computers as if the computers are not there and as if the people are using their own abilities or powers instead. I argue that facilitating unmediated interaction via personalization, new input modalities, and improved text entry can reduce both input overhead and output overhead, which are the burden of providing inputs to and receiving outputs from the intermediate device, respectively. I introduce three computational methods for reducing input overhead and one for reducing output overhead. First, I show how input data mining can eliminate the need for user inputs altogether. Specifically, I develop a method for mining controller inputs to gain deep insights about a players playing style, their preferences, and the nature of video games that they are playing, all of which can be used to personalize their experience without any explicit input on their part. Next, I introduce gaze locking, a method for sensing eye contact from an image that allows people to interact with computers, devices, and other objects just by looking at them. Third, I introduce computationally optimized keyboard designs for touchscreen manual input that allow people to type on smartphones faster and with far fewer errors than currently possible. Last, I introduce the racing auditory display (RAD), an audio system that makes it possible for people who are blind to play the same types of racing games that sighted players can play, and with a similar speed and sense of control as sighted players. The RAD shows how we can reduce output overhead to provide user interface parity between people with and without disabilities. Together, I hope that these systems open the door to even more efforts in unmediated interaction, with the goal of making computers less like devices that we use and more like abilities or powers that we have

Optimization-Based wearable tactile rendering

Novel wearable tactile interfaces offer the possibility to simulate tactile interactions with virtual environments directly on our skin. But, unlike kinesthetic interfaces, for which haptic rendering is a well explored problem, they pose new questions about the formulation of the rendering problem. In this work, we propose a formulation of tactile rendering as an optimization problem, which is general for a large family of tactile interfaces. Based on an accurate simulation of contact between a finger model and the virtual environment, we pose tactile rendering as the optimization of the device configuration, such that the contact surface between the device and the actual finger matches as close as possible the contact surface in the virtual environment. We describe the optimization formulation in general terms, and we also demonstrate its implementation on a thimble-like wearable device. We validate the tactile rendering formulation by analyzing its force error, and we show that it outperforms other approaches

Engineering data compendium. Human perception and performance. User's guide

The concept underlying the Engineering Data Compendium was the product of a research and development program (Integrated Perceptual Information for Designers project) aimed at facilitating the application of basic research findings in human performance to the design and military crew systems. The principal objective was to develop a workable strategy for: (1) identifying and distilling information of potential value to system design from the existing research literature, and (2) presenting this technical information in a way that would aid its accessibility, interpretability, and applicability by systems designers. The present four volumes of the Engineering Data Compendium represent the first implementation of this strategy. This is the first volume, the User's Guide, containing a description of the program and instructions for its use

Doctor of Philosophy

dissertationVirtual reality is becoming a common technology with applications in fields such as medical training, product development, and entertainment. Providing haptic (sense of touch) information along with visual and audio information can create an immersive vi

Supporting Eyes-Free Human–Computer Interaction with Vibrotactile Haptification

The sense of touch is a crucial sense when using our hands in complex tasks. Some tasks we learn to do even without sight by just using the sense of touch in our fingers and hands. Modern touchscreen devices, however, have lost some of that tactile feeling while removing physical controls from the interaction. Touch is also a sense that is underutilized in interactions with technology and could provide new ways of interaction to support users. While users are using information technology in certain situations, they cannot visually and mentally focus completely during the interaction. Humans can utilize their sense of touch more comprehensively in interactions and learn to understand tactile information while interacting with information technology. This thesis introduces a set of experiments that evaluate human capabilities to understand and notice tactile information provided by current actuator technology and further introduces a couple of examples of haptic user interfaces (HUIs) to use under eyes-free use scenarios. These experiments evaluate the benefits of such interfaces for users and concludes with some guidelines and methods for how to create this kind of user interfaces. The experiments in this thesis can be divided into three groups. In the first group, with the first two experiments, the detection of vibrotactile stimuli and interpretation of the abstract meaning of vibrotactile feedback was evaluated. Experiments in the second group evaluated how to design rhythmic vibrotactile tactons to be basic vibrotactile primitives for HUIs. The last group of two experiments evaluated how these HUIs benefit the users in the distracted and eyes-free interaction scenarios. The primary aim for this series of experiments was to evaluate if utilizing the current level of actuation technology could be used more comprehensively than in current-day solutions with simple haptic alerts and notifications. Thus, to find out if the comprehensive use of vibrotactile feedback in interactions would provide additional benefits for the users, compared to the current level of haptic interaction methods and nonhaptic interaction methods. The main finding of this research is that while using more comprehensive HUIs in eyes-free distracted-use scenarios, such as while driving a car, the user’s main task, driving, is performed better. Furthermore, users liked the comprehensively haptified user interfaces

Design and Evaluation of Neurosurgical Training Simulator

Surgical simulators are becoming more important in surgical training. Consumer smartphone technology has improved to allow deployment of VR applications and are now being targeted for medical training simulators. A surgical simulator has been designed using a smartphone, Google cardboard 3D glasses, and the Leap Motion (LM) hand controller. Two expert and 16 novice users were tasked with completing the same pointing tasks using both the LM and the medical simulator NeuroTouch. The novice users had an accuracy of 0.2717 bits (SD 0.3899) and the experts had an accuracy of 0.0925 bits (SD 0.1210) while using the NeuroTouch. Novices and experts improved their accuracy to 0.3585 bits (SD 0.4474) and 0.4581 bits (SD 0.3501) while using the LM. There were some tracking problems with the AR display and LM. Users were intrigued by the AR display and most preferred the LM, as they found it to have better usability