Presentation of Surface Height Profiles Based on Frequency Modulation at Constant Amplitude Using Vibrotactile Elements

This study attempted to observe what effects the frequency modulation of vibration elements produce in representing a tactile shape. Tactile shapes were modulated based on frequency difference at constant amplitude through a tactile feedback array of 30 (5 × 6) pins, which stimulated the finger pad. Experiment I showed that participants feel height changes when modulating frequency. In Experiment II, the participants were asked to discriminate three basic tactile shape patterns, which were generated with different frequencies at constant amplitude. Experiment II proved that spatial height information can be represented by modulating temporal information. In Experiment III, the frequency modulation method was applied to the tactile mouse system. Dynamic frequency modulation at passive touch can be used to transmit tactile height pattern information to the user of the mouse pointer for more practical application. The results showed that the participants were able to discern eight predefined shapes with an accuracy of 98.4% upon passive touch.     

Human shape recognition performance for 3D tactile display

The paper describes the relationship between the pin-matrix density of a tactile display and the recognition performance of displayed 3D shapes. Three types of pin-matrix tactile display, that generate 3D shapes, were used for the experiment. The pitch of pins was 2 mm, 3 mm, 5 mm each. We assumed that surfaces, edges, and vertices were primitive 3D shape information, so tested shapes were classified into these three categories. We assumed two types of finger touching mode: 1) fingertip-only, allowed full use of spatial shape information given to the fingertip; and 2) allowed tracing of the object. Recognition time and the classified error rate were measured. We obtained results on the relationship between pin pitch and recognition performance data. Regression curves for pin pitch and recognition time were plotted. A significance test of recognition time versus pin pitch was done. The error rate of identification versus pin pitch was described. Our results provide basic knowledge for developing tactile presentation devices     

KAT II: Tactile Display Mouse for Providing Tactile and Thermal Feedback

This paper proposes a tactile display mouse providing both pin-array-type tactile feedback and thermal feedback. The pin-array-type tactile display is composed of a 6 × 5 pin-array that is actuated by 30 piezo-electric bimorphs. Micro shape and vibrotactile feedback can be generated by the device, and various planar distributed patterns can be displayed as can Braille cell patterns. The thermal feedback device is composed of a thin-film resistance temperature detector, a Peltier thermoelectric heat pump and a water cooling jacket. Users can discriminate among different materials by considering the temperature variation that can be sensed as they touch an object's surface. This paper also includes an experimental evaluation of the tactile display mouse to prove the effectiveness of displaying textures. Evaluation of the ability to identify material properties was conducted using the thermal feedback part that displays a simulated temperature profile. To investigate thermo–tactile interaction, an experiment determining perceived magnitude of vibrotactile stimulus according to different temperature conditions was conducted.     

Tactile display with tangential and normal skin displacement for robot-assisted surgery

This paper proposes a tactile display providing both shear and normal feedback to the fingertip for generating three-axis tactile feedback during teleoperation of a surgical robot. The display is composed of five balloons actuated by controlling the pneumatic pressure. The implemented display is 18?mm?×?18?mm?×?15?mm. This size is suitable for mounting the display onto the master controls of a surgical robot. The maximum normal and shear displacements are 2 and 1.3?mm, respectively. The proposed tactile display may provide perceivable stimuli to a human finger pad in all five directions: normal, distal, proximal, radial, and ulnar. This paper also reports on the results of psychophysical measurement of the minimum perceivable movement of the developed tactile display for each of the five directions.     

SmartTouch: electric skin to touch the untouchable

Augmented haptics lets users touch surface information of any modality. SmartTouch uses optical sensors to gather information and electrical stimulation to translate it into tactile display. Augmented reality is an engineer's approach to this dream. In AR, sensors capture artificial information from the world, and existing sensing channels display it. Hence, we virtually acquire the sensor's physical ability as our own. Augmented haptics, the result of applying AR to haptics, would allow a person to touch the untouchable. Our system, SmartTouch, uses a tactile display and a sensor. When the sensor contacts an object, an electrical stimulation translates the acquired information into a tactile sensation, such as a vibration or pressure, through the tactile display. Thus, an individual not only makes physical contact with an object, but also touches the surface information of any modality, even those that are typically untouchable.     

Usage of multisensory information in scientific data sensualization

Multisensory scientific data sensualization methods that utilize virtual reality technology permit the use of several human sensations, such as visual, acoustic, and tactile sensation to display numerical data. The purposes of multisensory data sensualization can be classified as follows: (a) representing the relationships between different kinds of data; (b) displaying data utilizing sensory integration; and (c) representing conditions using the compound image. By using multisensory information, computers increase the ability to express data. However, these methods lead us to the question of which sensation should be used to display data most effectively. In this study, a multisensory data sensualization environment was developed in which color, loudness, sound frequency, and air flow pressure could be used to display scientific data. In particular, a wind sensation display prototype using air flow pressure was developed to generate tactile sensation. A basic experiment was conducted on sensory interference when subjects used two kinds of sensations simultaneously. From these results, guidelines for the usage of multisensory information for each purpose is proposed.     

振动触觉纹理再现技术研究综述

纹理力触觉再现是通过特定的硬件装置模拟产生与物体纹理表面接触时的触感，使用户能感受到物体的粗糙度、软硬度等纹理特征信息。振动刺激作为再现物体触觉信息的一种刺激方式，在纹理触觉再现中被广泛运用，产生了不同的振动触觉表达装置和纹理触觉表达方法。从纹理触觉认知的角度，阐述了人对振动刺激的触觉感知生理学基础；介绍了纹理触觉再现的原理和方法；从振动与纹理特征的映射方法以及振动刺激方式两个方面分析了目前振动触觉纹理再现技术的发展现状；最后对相关研究的发展进行了总结展望。     

A study of the discriminability of shape symbols by the foot

An experiment to test the discriminability of shape symbols using the shod foot was performed with 38 blind people (aged 23-72 years). Ten shape symbols which were 5 mm thick and fitted into a 30.5 cm2 tile were presented to subjects to identify by using only their feet. Each subject had 20 trials in which to discriminate the symbols. In each trial, a symbol was selected randomly and presented to the subject in randomized orientation. The subject was instructed to step on the symbol and to identify it using their own method. Time to discriminate a symbol and the accuracy of identification were recorded. A very high accuracy (93% on average) was obtained, which is comparable to the accuracy of tactile symbol discrimination using the hands. Average time to discriminate a symbol was 16 s with a standard deviation of 12.15 s, which indicated the high variability of the results. Owing to the high accuracy of identification, tactile foot-discriminable symbols have great potential as landmarks for blind people and if applied to a tactile guide path they could provide information for orientation and navigation.     

A study of the discriminability of shape symbols by the foot

An experiment to test the discriminability of shape symbols using the shod foot was performed with 38 blind people (aged 23–72 years). Ten shape symbols which were 5 mm thick and fitted into a 30.5cm² tile were presented to subjects to identify by using only their feet. Each subject had 20 trials in which to discriminate the symbols. In each trial, a symbol was selected randomly and presented to the subject in randomized orientation. The subject was instructed to step on the symbol and to identify it using their own method. Time to discriminate a symbol and the accuracy of identification were recorded. A very high accuracy (93% on average) was obtained, which is comparable to the accuracy of tactile symbol discrimination using the hands. Average time to discriminate a symbol was 16 s with a standard deviation of 12.15 s, which indicated the high variability of the results. Owing to the high accuracy of identification, tactile foot-discriminable symbols have great potential as landmarks for blind people and if applied to a tactile guide path they could provide information for orientation and navigation.     

Detection of temporal delays in visual-haptic interfaces

This paper addresses the question of how large the temporal delay between a visual and a haptic stimulus may be such that the stimuli are still perceived as being synchronous. Participants had to judge whether the moment at which a graphical object collided with a virtual wall occurred simultaneously with the moment at which a force was felt through a force feedback joystick. Participants either moved the joystick to drive the object (active touch) or held the joystick in a steady position while the object moved by itself (passive touch). Participants were found to be very sensitive to visual-haptic time delays. Sensitivity was higher for passive touch than for active touch. The minimum delay at which participants judged the stimuli as asynchronous was on average 45 ms. The delay at which the proportion of synchronous judgments reached a maximum was on average close to zero. The results indicate that the temporal accuracy of visual-haptic interfaces has to meet stringent requirements in order to optimize the overall realism that users experience. Actual or potential applications of this research include teleoperation, medical training, computer-aided-design, and scientific visualization.     

Ripple phenomenon of displays with nematic liquid crystal

Liquid crystal displays will show ripple if the display surface or display bracket is subjected to tactile forces. In this paper, the ripple of liquid crystal displays is investigated by dealing with elastic wave propagation in a liquid crystal layer. The model proposed for a visco‐elastic medium like liquid crystals (LCs) is generalized by combining the properties of a crystalline solid and an anisotropic fluid. The governing equation is derived by using visco‐elastic and wave equations. In the experiments, a linear motor is used to touch the display panel for producing ripple. Displays of three different amounts of LCs are compared. Experimental results also show that each display panel has its own wave propagation velocity that is not changed by different motor touch speeds. In addition, both theoretical analysis and experimental results depict that displays with a larger amount of LCs lead to slower ripple speed.     

Capacitive touchscreen‐integrated electrostatic tactile display with localized sensation

An electrostatic tactile display with a projected capacitive touchscreen integrated into a single panel was demonstrated. Every electrode on the panel is driven for both tactile presentation and the touch sensor. The functions are both time and spatially multiplexed, and a reference–node‐driven high‐pass filter in the touch controller filters out the noise from the tactile driving signals.     

Selectively stimulating skin receptors for tactile display

Research in virtual reality has recognized the need for more realistic tactile display in addition to touch and non-touch display and force display. We propose a method of selectively stimulating only superficial mechanoreceptors. We show that it makes people feel a more realistic, finer virtual texture than possible by adjusting the stimulator spacing. The apparatus is simple and we expect this idea to develop into a device to display varieties of tactile feeling     

A gap detection tactility test for sensory deficits associated with carpal tunnel syndrome

An automated gap detection tactility test was investigated for quantifying sensory deficits associated with carpal tunnel syndrome (CTS). The test, which involved sensing a tiny gap in an otherwise smooth surface by probing with the finger, had functional resemblance to many work-related tactile activities such as detecting scratches or surface defects. Gap detection thresholds were measured using the converging staircase method of limits paradigm. Sixteen normal subjects between 21 and 66 years of age were tested for studying important factors affecting gap detection thresholds. Actively probing with the index finger had a threshold almost an order of magnitude more sensitive (mean = 0·19mm, SD = 0·llmm) than passive touch (mean =1·63mm. SD = 0·62mm), which was similar to two-point discrimination. Average thresholds decreased by 24% as contact force increased from 25 to 75?g. Performance in this tactility test quickly stabilized and showed little learning effects over the period of the test, as evidenced by the lack of significant differences between six replicates. The results were highly repeatable. No significant threshold differences were observed between test and retest trials on different days, or between dominant and non-dominant hands. A contact force of 50?g was recommended as optimal for this test since it required moderate force but resulted in a smaller threshold compared with 25 or 75?g. A companion study was conducted using eight normal subjects and ten subjects diagnosed as having CTS. Average gap detection threshold, when finger probing was allowed, was 0·20?mm (SD = 0·11?min) for the normal subjects and increased two-fold to 0·40?mm (SD = 0·19?mm) for the CTS subjects. Average gap detection threshold, when the finger probing was not allowed, was 1·71?mm (SD = 0·53mm) for the normal subjects and increased by 48% to 2·53?mm (SD = 0·87?mm) for the CTS subjects. The results suggest that people suffering from CTS may experience similar functional deficits in daily living and work activities. The small inter-subject variability makes this test a candidate for having utility as a monitoring test for loss of cutaneous tactile sensitivity.     

Feasibility study of tactile-based authentication

Research suggests that human limitations are rarely considered in the design of knowledge-based authentication systems. In an attempt to foster entry to a system, individuals tend to choose passwords which are easy to recall. However, inappropriate selection can compromise data security. A novel approach has been developed to restore the balance between security and memorability through the use of the haptic channel. This paper introduces the Tactile Authentication System (TAS), which enables the user to authenticate entry through the ability to remember a sequence of pre-selected tactile sensations. The design process undertaken to develop distinguishable tactile stimuli for use within TAS is described, and details of the recognition-based tactile authentication mechanism are also presented. Findings from an empirical study reported in this paper, have revealed that 16 participants were able to authenticate access to TAS over the course of a one-month period, with low levels of error. The approach was found to offer benefits over conventional visual-based authentication methods. Tactile stimuli are presented underneath the fingertips, and are therefore occluded from others. As the sense of touch is personal to each user, tactile stimuli are difficult to describe in concrete terms, and cannot easily be written down or disclosed, thereby reducing the chance of unauthorized third party access.     

Demonstration of a technological prototype of an active‐matrix BiNem liquid‐crystal display

Abstract— The first implementation of active‐matrix addressing on a BiNem bistable nematic liquid‐crystal display has been demonstrated. Compared to previous passive‐matrix addressing, major improvements have been made for the bistable mode: a smoother image refreshment, shorter refreshing frame time compatible with that of high‐resolution e‐book displays, the use of a touch screen for interactive functions such as hand‐writing, a virtual keyboard, improved functionality for scrolling menus, partial refreshment, etc. On the same display but in the monostable mode, by using electrically controlled birefringence (ECB), the potential of displaying moving pictures at a rate of 25 images/sec, at an extended room temperature, has been demonstrated. In the ECB monostable mode, static images can be displayed down to ?20°C. A new transflective single‐polarizer optical mode has been developed to optimize the indoor and outdoor readability of the display. By lowering the surface reflection and enhancing the panel transmission, a contrast ratio of 94:1 and a transmittance of 17% have been achieved.     

Equivalent comfort contours for vertical vibration of steering wheels: effect of vibration magnitude, grip force, and hand position

Vehicle drivers receive tactile feedback from steering-wheel vibration that depends on the frequency and magnitude of the vibration. From an experiment with 12 subjects, equivalent comfort contours were determined for vertical vibration of the hands at two positions with three grip forces. The perceived intensity of the vibration was determined using the method of magnitude estimation over a range of frequencies (4-250 Hz) and magnitudes (0.1-1.58 ms⁻² r.m.s.). Absolute thresholds for vibration perception were also determined for the two hand positions over the same frequency range. The shapes of the comfort contours were strongly dependent on vibration magnitude and also influenced by grip force, indicating that the appropriate frequency weighting depends on vibration magnitude and grip force. There was only a small effect of hand position. The findings are explained by characteristics of the Pacinian and non-Pacinian tactile channels in the glabrous skin of the hand.     

用于表达飞行姿态信息的组合式振动触觉编码

通过触觉传感帮助飞行员准确感知飞行姿态信息,减轻视听觉认知负担是信息的非视觉表达的一种大胆而有效途径.为此,设计了一种能提示飞机偏转方向和偏转角度的振动触觉显示方法.该方法充分考虑人对振动触觉刺激的敏感特性将姿态信息映射为一定振动节奏、振动位置和振动次序,从而形成组合式振动触觉编码,通过穿戴式振动触觉提示背心提示给人.与单控制参数的映射编码模式相比,该方法能显著提高振动表达的识别率,同时降低认知载荷.不同编码方法的感知识别实验表明,本方法在识别准确率,响应时间和训练时间上优于其他传统方法.     

Mechanical feedback analysis of a ferrofluid-based module with 2D dynamic traveling waves for tactile display application

With the advances of human-machine systems, tactile displays have become one of the important features for modern products. Tactile feedback can increase working efficiency and help humans to explore new environments or objects by the sense of touch. This study used a 3 × 3 electromagnet array and a ferrofluid bladder to build a tactile display module, which can create smooth and continuous real-time 2-D dynamic traveling waves. The interactions of magnetic fields between electromagnets in the array were used to control the directions of the magnetic lines of force to create different graph patterns. Our user test showed that the overall tactile perception rate was 74% for the 2-D dynamic graph patterns generated using the ferrofluid-based tactile display module.     

视听触同步刺激的数字化盲文学习方法

盲文是视障人士获取信息,学习知识的重要媒介.然而,目前基于纸质书籍的盲文学习方法只能提供盲文点位的触觉刺激,存在不便携、不易用且内容陈旧等问题.为此,本文提出了一种视觉、听觉和触觉同步刺激的数字化盲文学习方法,能够提高视障人士的盲文学习效率.基于多感知盲文学习机,本文设计了一种多感知信息匹配算法,能够输出文字、声音和盲文点位相同内容的信息,为视障人士无障碍学习盲文提供条件.短期记忆的盲文学习效果实验表明:(1)在视觉、听觉和触觉的共同刺激下,盲文学习效率最高,即在盲文学习过程中,增加视觉刺激对于视力残余人士提升盲文学习效率有显著正向促进作用;(2)在听觉和触觉的共同刺激下,盲文学习效率并不高,即全盲人士学会盲文有一定难度,需要有较长的学习曲线;(3)仅在听觉刺激下,盲文学习效率很低,即开发语音学盲文的APP不具备实践意义.