Electrostatic Friction Displays to Enhance Touchscreen Experience

Touchscreens are versatile devices that can display visual content and receive touch input, but they lack the ability to provide programmable tactile feedback. This limitation has been addressed by a few approaches generally called surface haptics technology. This technology modulates the friction between a user’s fingertip and a touchscreen surface to create different tactile sensations when the finger explores the touchscreen. This functionality enables the user to see and feel digital content simultaneously, leading to improved usability and user experiences. One major approach in surface haptics relies on the electrostatic force induced between the finger and an insulating surface on the touchscreen by supplying high AC voltage. The use of AC also induces a vibrational sensation called electrovibration to the user. Electrostatic friction displays require only electrical components and provide uniform friction over the screen. This tactile feedback technology not only allows easy and lightweight integration into touchscreen devices but also provides dynamic, rich, and satisfactory user interfaces. In this chapter, we review the fundamental operation of the electrovibration technology as well as applications have been built upon

Enhancing touch sensibility by sensory retraining in a sensory discrimination task via haptic rendering

Stroke survivors are commonly affected by somatosensory impairment, hampering their ability to interpret somatosensory information. Somatosensory information has been shown to critically support movement execution in healthy individuals and stroke survivors. Despite the detrimental effect of somatosensory impairments on performing activities of daily living, somatosensory training—in stark contrast to motor training—does not represent standard care in neurorehabilitation. Reasons for the neglected somatosensory treatment are the lack of high-quality research demonstrating the benefits of somatosensory interventions on stroke recovery, the unavailability of reliable quantitative assessments of sensorimotor deficits, and the labor-intensive nature of somatosensory training that relies on therapists guiding the hands of patients with motor impairments. To address this clinical need, we developed a virtual reality-based robotic texture discrimination task to assess and train touch sensibility. Our system incorporates the possibility to robotically guide the participants' hands during texture exploration (i.e., passive touch) and no-guided free texture exploration (i.e., active touch). We ran a 3-day experiment with thirty-six healthy participants who were asked to discriminate the odd texture among three visually identical textures –haptically rendered with the robotic device– following the method of constant stimuli. All participants trained with the passive and active conditions in randomized order on different days. We investigated the reliability of our system using the Intraclass Correlation Coefficient (ICC). We also evaluated the enhancement of participants' touch sensibility via somatosensory retraining and compared whether this enhancement differed between training with active vs. passive conditions. Our results showed that participants significantly improved their task performance after training. Moreover, we found that training effects were not significantly different between active and passive conditions, yet, passive exploration seemed to increase participants' perceived competence. The reliability of our system ranged from poor (in active condition) to moderate and good (in passive condition), probably due to the dependence of the ICC on the between-subject variability, which in a healthy population is usually small. Together, our virtual reality-based robotic haptic system may be a key asset for evaluating and retraining sensory loss with minimal supervision, especially for brain-injured patients who require guidance to move their hands

HAPTIC VISUALIZATION USING VISUAL TEXTURE INFORMATION

Haptic enables users to interact and manipulate virtual objects. Although haptic research has influenced many areas yet the inclusion of computer haptic into computer vision, especially content based image retrieval (CBIR), is still few and limited. The purpose of this research is to design and validate a haptic texture search framework that will allow texture retrieval to be done not just visually but also haptically. Hence, this research is addressing the gap between the computer haptic and CBIR fields. In this research, the focus is on cloth textures. The design of the proposed framework involves haptic texture rendering algorithm and query algorithm. The proposed framework integrates computer haptic and content based image retrieval (CBIR) where haptic texture rendering is performed based on extracted cloth data. For the query purposes, the data are characterized and the texture similarity is calculated. Wavelet decomposition is utilized to extract data information from texture data. In searching process, the data are retrieved based on data distribution. The experiments to validate the framework have shown that haptic texture rendering can be performed by employing techniques that involve either a simple waveform or visual texture information. While rendering process was performed instability forces were generated during the rendering process was due to the limitation of the device. In the query process, accuracy is determined by the number of feature vector elements, data extraction, and similarity measurement algorithm. A user testing to validate the framework shows that users’ perception of haptic feedback differs depending on the different type of rendering algorithm. A simple rendering algorithm, i.e. sine wave, produces a more stable force feedback, yet lacks surface details compared to the visual texture information approach

Modern Applications of Electrostatics and Dielectrics

Electrostatics and dielectric materials have important applications in modern society. As such, they require improved characteristics. More and more equipment needs to operate at high frequency, high voltage, high temperature, and other harsh conditions. This book presents an overview of modern applications of electrostatics and dielectrics as well as research progress in the field

Markov-Gibbs Random Field Approach for Modeling of Skin Surface Textures

Medical imaging has been contributing to dermatology by providing computer-based assistance by 2D digital imaging of skin and processing of images. Skin imaging can be more effective by inclusion of 3D skin features. Furthermore, clinical examination of skin consists of both visual and tactile inspection. The tactile sensation is related to 3D surface profiles and mechanical parameters. The 3D imaging of skin can also be integrated with haptic technology for computer-based tactile inspection. The research objective of this work is to model 3D surface textures of skin. A 3D image acquisition set up capturing skin surface textures at high resolution (~0.1 mm) has been used. An algorithm to extract 2D grayscale texture (height map) from 3D texture has been presented. The extracted 2D textures are then modeled using Markov-Gibbs random field (MGRF) modeling technique. The modeling results for MGRF model depend on input texture characteristics. The homogeneous, spatially invariant texture patterns are modeled successfully. From the observation of skin samples, we classify three key features of3D skin profiles i.e. curvature of underlying limb, wrinkles/line like features and fine textures. The skin samples are distributed in three input sets to see the MGRF model's response to each of these 3D features. First set consists of all three features. Second set is obtained after elimination of curvature and contains both wrinkle/line like features and fine textures. Third set is also obtained after elimination of curvature but consists of fine textures only. MGRF modeling for set I did not result in any visual similarity. Hence the curvature of underlying limbs cannot be modeled successfully and makes an inhomogeneous feature. For set 2 the wrinkle/line like features can be modeled with low/medium visual similarity depending on the spatial invariance. The results for set 3 show that fine textures of skin are almost always modeled successfully with medium/high visual similarity and make a homogeneous feature. We conclude that the MGRF model is able to model fine textures of skin successfully which are on scale of~ 0.1 mm. The surface profiles on this resolution can provide haptic sensation of roughness and friction. Therefore fine textures can be an important clue to different skin conditions perceived through tactile inspection via a haptic device

Fundamental Limits in The Rendering of Virtual Haptic Textures

We discuss the properties of force-feedback haptic simulation systems that fundamentally limit the re-creation of periodic gratings, and hence, of any texture. These include sampling rate, device resolution, and structural dynamics. Basic sampling limitations are analyzed in terms of the Nyquist and the Courant conditions. The analysis proposes that noise due to sampling and other sources injected in the system may prevent it to achieve acceptable performance in most operating conditions, unless special precautions such as the use of a reconstruction filter, make the closed-loop more robust to noise. The structural response of a PHANTOM 1.0A device was such that no such filter could be found, and the system introduced heavy distortion in gratings as coarse as 10 mm. The Pantograph Mark-II device having more favorable structural properties could reliably create gratings between 1 and 10 mm

The feasibility of using virtual prototyping technologies for product evaluation

With the continuous development in computer and communications technology the use of computer aided design in design processes is becoming more commonplace. A wide range of virtual prototyping technologies are currently in development, some of which are commercially viable for use within a product design process. These virtual prototyping technologies range from graphics tablets to haptic devices. With the compression of design cycles the feasibility of using these technologies for product evaluation is becoming an ever more important consideration. This thesis begins by presenting the findings of a comprehensive literature review defining product design with a focus on product evaluation and a discussion of current virtual prototyping technologies. From the literature review it was clear that user involvement in the product evaluation process is critical. The literature review was followed by a series of interconnected studies starting with an investigation into design consultancies' access and use of prototyping technologies and their evaluation methods. Although design consultancies are already using photo-realistic renderings, animations and sometimes 3600 view CAD models for their virtual product evaluations, current virtual prototyping hardware and software is often unsatisfactory for their needs. Some emergent technologies such as haptic interfaces are currently not commonly used in industry. This study was followed by an investigation into users' psychological acceptance and physiological discomfort when using a variety of virtual prototyping tools for product evaluation compared with using physical prototypes, ranging from on-screen photo-realistic renderings to 3D 3600 view models developed using a range of design software. The third study then went on to explore the feasibility of using these virtual prototyping tools and the effect on product preference when compared to using physical prototypes. The forth study looked at the designer's requirements for current and future virtual prototyping tools, design tools and evaluation methods. In the final chapters of the thesis the relative strengths and weaknesses of these technologies were re-evaluated and a definitive set of user requirements based on the documentary evidence of the previous studies was produced. This was followed by the development of a speculative series of scenarios for the next generation of virtual prototyping technologies ranging from improvements to existing technologies through to blue sky concepts. These scenarios were then evaluated by designers and consumers to produce documentary evidence and recommendations for preferred and suitable combinations of virtual prototyping technologies. Such hardware and software will require a user interface that is intuitive, simple, easy to use and suitable for both the designers who create the virtual prototypes and the consumers who evaluate them