Tactile Display Device Research Articles

Design and Psychophysical Evaluation of a Novel Wearable Upper-Arm Tactile Display Device.

A novel wearable upper arm tactile display device, which can simultaneously provide three types of tactile stimuli (i.e., squeezing, stretching, and vibration) is presented. The squeezing and stretching stimulation of the skin is generated by two motors simultaneously driving the nylon belt in the opposite and the same direction, respectively. In addition, four evenly spaced vibration motors are fixed around the user's arm by an elastic nylon band. There is also a unique structural design for assembling the control module and actuator, powered by two lithium batteries, making it portable and wearable. Psychophysical experiments are conducted to investigate the effect of interference on the perception of squeezing and stretching stimulation by this device. Results show that (1) different tactile stimuli actually interfere with the user's perception compared to the case where only one stimulus is applied to the user; (2) the squeezing has a considerable impact on the stretch just noticeable difference (JND) values when both stimuli are exerted on the user, and when the squeezing is strong, while the impact of stretch on the squeezing JND values is negligible.

Simulating mechanical properties of human tissues or organs based on magnetorheological fluid for tactile display

Robot-assisted minimally invasive surgery enables surgeons to tele-perform elaborate surgical operations to patients with less damage and pain. Besides force feedback provided by the surgical robot to the surgeon, touching sensations are also important for the surgeon to acquire the complete conditions of the patient. Thus, tactile display devices are crucial elements in surgical robots. Meanwhile, various sensations of magnetorheological (MR) fluid can be provided to human fingers because its stiffness, elasticity, and viscosity can be controlled by applied magnetic field. Therefore, in this paper, a new tactile display device based on MR fluid is proposed. This device has high magnetic conduction efficiency, less magnetic leakage, no MR fluid leakage, and overcomes the major drawbacks of the existing tactile display devices based on MR fluid in literatures. Firstly, the design of the tactile display device is described in detail, followed by its fabrication and assembling methods. Secondly, the working current range of the tactile display device is determined by using electromagnetic finite element method (FEM) simulation. Thirdly, the mathematical model to characterize the compression and shear behaviors of the tactile display device is developed. Then, the tactile display device is tested in terms of normal and shear contact forces, followed by its elastic and shear moduli analysis. Finally, the unknown parameters in the mathematical model are figured out, and the model is validated by using structural FEM simulation. The experimental results show that the elastic and shear modulus range of the proposed tactile display device are respectively 3–7.5 kPa and 1.4–5.0 kPa, which can cover the mechanical properties of various human viscera.

Vibrotactile Threshold Measurements at the Wrist Using Parallel Vibration Actuators

This article presents an investigation into the perceptual vibrotactile thresholds for a range of frequencies on both the inside and outside areas of the wrist when exciting the skin with parallel vibrations, realized using the L5 actuator made by Lofelt GmbH. The vibrotactile threshold of 30 participants was measured using a modified audiometry test for the frequency range of 25–1,000 Hz. The average threshold across the respective frequencies was then ultimately determined from acceleration minima. The results show that maximum sensitivity lies in the range of 100–275 Hz (peaking at 200 Hz) for the inside and 75–250 Hz (peaking at 125 Hz) for the outside of the wrist and that thresholds are overall higher for the hairy skin on the outside of the wrist than for the glabrous skin on the inside. The results also show that the vibrotactile thresholds varied highly between individuals. Hence, personalized threshold measurements at the actuator locations will be required to fine-tune a device for the user. This study is a part of an ongoing research and development project where the aim is to develop a tactile display device and a music encoding scheme with the purpose of augmenting the musical enjoyment of cochlear implant recipients. These results, along with results from planned follow-up experiments, will be used to determine the appropriate frequency range and to cast light on the dynamic range on offer for the tactile device.

Design of Fully Controllable and Continuous Programmable Surface Based on Machine Learning

Programmable surfaces (PSs) consist of a 2D array of actuators that can deform in the third dimension, providing the ability to create continuous 3D profiles. Discrete PSs can be realized using an array of independent solid linear actuators. Continuous PSs consist of actuators that are mechanically coupled, providing deformation states that are more similar to real surfaces with reduced complexity of the control electronics. However, continuous PSs have been limited in size by the lack of the control systems required to take into account the complex internal coupling between actuators in the array. In this work, we computationally explore the deformation of a fully continuous PS with 81 independent actuation pixels based on ionic bending actuator. We establish a control strategy using machine learning (ML) regression models. Both forward and inverse control are achieved based on the training datasets which are derived from the finite element analysis (FEA) data of our PS. The prediction of surface deformation achieved by forward control with accuracy under 1% is 15000 times faster than FEM. And the real-time inverse control of continuous PSs that is to reproduce any arbitrary pre-defined surfaces, which possess high practical value for tactile display or human-machine interactive devices, is first proposed in the letter.

Touch and See? Regarding Images in the Era of the Interface

Not only are we now surrounded by a plethora of images that derive from automatic mechanical protocols, “technical images” as Wilém Flusser would call them, but vision itself is controlled by technological processes—manually activated interfaces that condition the appearance of images in terms of size, quality and resolution, as well as duration. Our experience as viewers increasingly become that of “users”: we touch the screen to activate a menu and select a resolution, to choose and enlarge an image, zoom into it or reduce its size, to start or pause a video, to scroll through or superimpose images, to slow down or speed up their course, to make them disappear. Not that the involvement of the hand turns the interface into the equivalent of a tool, which is a prolongation of the body. Unlike the tool, touch screens belong to the realm of the programmed machine. To evaluate the effect of technology over the culturality of gestures as well as vision was one of Flusser’s key projects, one whose import comes to the fore with particular force in the digital era, when visuality appears to increasingly escape the realm of purely visual phenomenon. In what follows, I refer to Flusser’s far-sighted work, as well as concepts of the fold as derived from Leibnitz and Gilles Deleuze by Laura U. Marks, in order to look at the ways in which interfaces and gestures, that are associated with tactile display devices, determine the form and effect of image reception in the context of our contemporary “economy of attention.” To this end, I rely also on the description and critical assessment of a work of art by artist Thomas Hirschhorn, Touching Reality (2012), whose combination of classical video display with an interface, showing deliberately controversial images, brings the question of reception into sharp focus.

TactViz: A VMD Plugin for Tactile Visualization of Protein Structures

Scientific disciplines spanning biology, biochemistry, and biophysics involve the study of proteins and their functions. Visualization of protein structures represents a barrier to education and research in these disciplines for students who are blind or visually impaired. Here, we present a software plugin for readily producing variable-height tactile graphics of proteins using the free biomolecular visualization software Visual Molecular Dynamics (VMD) and protein structure data that is publicly available through the Protein Data Bank. Our method also supports interactive tactile visualization of proteins with VMD on electronic refreshable tactile display devices. Employing our method in an academic laboratory has enabled an undergraduate student who is blind to carry out research alongside her sighted peers. By making the study of protein structures accessible to students who are blind or visually impaired, we aim to promote diversity and inclusion in STEM education and research.

Fabrication of Tactile Display Device with Individually-driven-type Shape Memory Alloy Thick Film Actuator Array

Fabrication of Tactile Display Device with Individually-driven-type Shape Memory Alloy Thick Film Actuator Array

Fabrication and Stiffness Evaluation of Ni Thin Film Flat-type Spring with Micro-pin and Frame Structure for Tactile Display Device

Fabrication and Stiffness Evaluation of Ni Thin Film Flat-type Spring with Micro-pin and Frame Structure for Tactile Display Device

가상제조환경에서 제품의 표면 거칠기 전달을 위한 촉각 디스플레이

In smart factories, the entire manufacturing process from design to the final product is simulated in a virtual manufacturing environment and optimized before starting production. Suppliers and customers make decisions based on the simulation results. Therefore, effective rendering of the information of the virtual products to suppliers and customers is essential for this manufacturing paradigm. In this study, a method of rendering the surface roughness of the virtual products using a tactile display is presented. A tactile display device comprising a 3 x 3 array of individually controlled piezoelectric stack actuators is constructed. The surface topology of the virtual products is rendered directly by controlling the piezoelectric stack actuators. A series of experiments is performed to evaluate the performance of the tactile display device. An electrical discharge machined surface is rendered using the proposed method.

Tactile display with rigid coupling based on soft actuator

The tactile display is a device which physically stimulates the human skin to reproduce the feel of touch. This paper presents a novel tactile display device driven by a dielectric elastomer actuator. The device adopts an indirect actuation method by using a rigid coupling, which aims to avoid direct contact of the human skin with the actuator. The rigid coupling is made of silicone to transmit the movement of the actuator to the touch layer located on the top surface of the coupling and provides the feeling of softness on contact. The device produces displacement about 350–140 μm at 0.3–10 Hz, which meets frequency requirements for simulating the Merkel cells as well as Meissner corpuscle. The force to simulate the fingertips can be exerted over 44 mN. This work describes its design, analysis and fabrication method in details with its experimental evaluations.

Design, characterization and control of SMA springs-based multi-modal tactile display device for biomedical applications

Tactile display is recently attracting much attention in the field of human–computer interaction. There is a strong need for such a device especially for applications in which the touch feeling is lost, such as surgeons who are willing to feel the tissue hardness during laparoscopic surgeries. In this paper, a novel multi-modal tactile display device which can display both surface shape and stiffness of an object is introduced. The conceptual design is built upon using two springs, made of Shape Memory Alloys (SMA), for displaying shape and stiffness. The design parameters of this device are selected based on the spatial resolution of human finger and the elasticity range of the soft tissue. The display device is simulated using Finite Element Method (FEM) to study the effect of design parameters on the resulting stiffness. Simulation results show that the device can display stiffness of an object independent of its shape display. The experimental setup is built and used for the characterization and control of the SMA springs. Experimental results show that the device can display a stiffness range of (35–110)N/m and elongation up to 5mm.

A flexible multimodal tactile display array for virtual shape and texture

Multimodal tactile display systems that are capable of delivering versatile tactile information effectively are of great interest for virtual reality and tele-operation applications. In this paper, we present a new flexible multimodal tactile display system that delivers shape and texture information simultaneously using a single actuator. The proposed tactile display is actuated by a combination of electromagnetic and pneumatic forces and thus exhibits high tactile force to deliver shape information and large vibration amplitude to deliver texture information. In addition, the proposed tactile display device was implemented on a flexible PDMS structure to allow for tight attachment on any curved body to transfer reliable tactile information. By applying a current pulse of 300 mA for 5 ms, we readily controlled the state of the tactile actuator and measured the actuation displacement of 900 μm and the generated force of 20.1 gf. The average vibration amplitude of 30 μm was measured over a wide dynamic range (25---650 Hz) with an applied current of 74 mA. Lastly, by delivering various tactile information to users, we verified the functionalities of the implemented 4 ? 1 multimodal tactile display array. User study results showed that the fabricated multimodal tactile display system successfully delivered both shape information with an accuracy of 73 % and texture information with an accuracy of 90 %. This work demonstrates the potential of our multimodal tactile display system for uses in various applications such as tele-operation, tactile communication, and visual presentation for visually impaired.

Displaying Sensed Tactile Cues with a Fingertip Haptic Device.

Telerobotic systems enable humans to explore and manipulate remote environments for applications such as surgery and disaster response, but few such systems provide the operator with cutaneous feedback. This article presents a novel approach to remote cutaneous interaction; our method is compatible with any fingertip tactile sensor and any mechanical tactile display device, and it does not require a position/force or skin deformation model. Instead, it directly maps the sensed stimuli to the best possible input commands for the device's motors using a data set recorded with the tactile sensor inside the device. As a proof of concept, we considered a haptic system composed of a BioTac tactile sensor, in charge of measuring contact deformations, and a custom 3-DoF cutaneous device with a flat contact platform, in charge of applying deformations to the user's fingertip. To validate the proposed approach and discover its inherent tradeoffs, we carried out two remote tactile interaction experiments. The first one evaluated the error between the tactile sensations registered by the BioTac in a remote environment and the sensations created by the cutaneous device for six representative tactile interactions and 27 variations of the display algorithm. The normalized average errors in the best condition were 3.0 percent of the BioTac's full 12-bit scale. The second experiment evaluated human subjects' experiences for the same six remote interactions and eight algorithm variations. The average subjective rating for the best algorithm variation was 8.2 out of 10, where 10 is best.

A polydimethylsiloxane diaphragm integrated with a sputtered thin film NdFeB magnet

In this paper we propose a MEMS fabrication process that enables a polydimethylsiloxane (PDMS) diaphragm to be integrated with a sputtered thin film permanent magnet (TFPM), which can be used for micro pumps, energy harvesters, tactile display devices and so on. The magnetic performance of the 14.8 μm thick TFPM, consisting of multilayers of 300 nm thick NdFeB and 10 nm thick Ta deposited sequentially, is as high as a conventional bulk NdFeB magnet. However, the high sputtering temperature makes it impossible to deposit the TFPM directly onto the PDMS diaphragm without damaging the PDMS material. The process proposed here involves, firstly, sputtering the TFPM onto a silicon substrate, then coating this with PDMS, and finally etching silicon using XeF2 gas. The high substrate temperature during the XeF2 etching process degraded the magnetic performance of the TFPM and also caused part of the TFPM to become detached from the PDMS layer. The variation in temperature of the substrate during the XeF2 etching process with respect to etching pressure, and the magnetic properties of the TFPM as well as the mechanical ones of the PDMS diaphragm were evaluated experimentally. The substrate temperature can be decreased by reducing the XeF2 etching pressure, thus avoiding both degradation of the magnetic performance of the TFPM and delamination of the TFPM. The results of the evaluation show that the PDMS diaphragm and the TFPM not only remained attached, but also retained their mechanical and magnetic properties.

Design Procedure and Simulation of a Novel Multi-Modal Tactile Display Device for Biomedical Applications

Tactile display is recently attracting much attention in the field of human computer interaction. There is a strong need for such a device especially for application in which the touch feeling is lost, such as surgeons willing to feel the tissue hardness during laparoscopic surgeries. In this paper, a novel multi-modal tactile display device which can display both surface shape and stiffness of an object is introduced. The conceptual design is built upon using two springs, made of Shape Memory Alloys-SMA, to control both shape and stiffness. The design parameters of this device are selected based on the spatial resolution of human finger and the stiffness range of the soft tissue. The display device is simulated using Finite Element Method, FEM, to study the effect of design parameters on the resulting stiffness. The results showed that the device can display stiffness of an object independent of its shape display. Simulation results confirmed that the stiffness display is stable when applying force by the finger during indentation for feeling stiffness, since the total stiffness error does not exceed 1.2%.

Design analysis and fabrication of arrayed tactile display based on dielectric elastomer actuator

The tactile display is an important tool to help the human interact with machines by using feels of touch. In this paper, we present a multiply arrayed tactile display device with Dielectric Elastomer Actuator (DEA). The device employs the liquid coupling between the touch spot and the actuator as the transmission of force. It is designed to ensure the comfort of touch and the safety of operation for the users while contacting with the human skin. The operating principle is explained in details, and a systematic design analysis is given. The displacements of tactile display is about 240–120μm at 3–10Hz, which satisfies the frequency requirements for simulating the Merkel cells as well as the Meissner corpuscles and the force is over 40mN to simulate the finger tip. In addition, a dedicated fabrication method and performance measurements are explained.

Assistive Navigation Device for Visually Impaired—A Study on Reaction Time to Tactile Modality Stimuli

A tactile system to support severe visually-impaired or blind people in the world for their orientation and navigation had been developed. To optimize the design, some parameters of tactile display device were evaluated. In the present paper,we focused on the reaction time to tactile stimuli. In the test, the stimuli were produced through a vibration belt that was worn around the participants’ waist. In the choice reaction time task, the participants had to click corresponding arrow keys according to the location of a tactile signal. The findings of this study provided a reference of the reaction time range, so as to design a more effective and safe tactile navigation system.

Design of Braille Display System Based on Piezoelectric Actuator Array

According to the situation that conditional Braille book is difficulty in publication and its amount is small. This paper puts forward a tactile display system which can transform content of common e-book to Braille information, and the blind comprehend the text by touching the Braille formed by the tactile display device. This Braille tactile display system extracts Chinese characters by OCR technology. The text recognized is segmented into word blocks according to the rule of Braille word segmentation before transforming to double-phoneme mandarin Braille. It uses dsPIC30F2010 to receive Braille signal and then controls the piezoelectric actuator array to output corresponding displacement.

Development of Tactile Display Device Using ERG Multiple-disk Clutch

Nowadays, due to the widespread use of rehabilitation and virtual reality technology, tactile display systems have attracted the attention of researchers from the medical and amusement fields. A clutch mechanism that employs ER and MR fluids is appropriate for force transmission in a tactile display device, because the ER and MR effects are passive and safe for the operator compared with an active actuator using motor. The developed ERG produces approximately 20 times higher shear forces than ER fluid and exhibits stable performance. In this research, an ERG multiple-disk clutch is fabricated and applied to a tactile display system. The experimental results of the control test indicate that the tactile display system with the proposed control method can exhibit the ‘sense of touch’ of various viscous fluids.

Design of a Wearable Fingertip Haptic Braille Device

Existing technologies and devices have facilitated the interaction of the blind or visually impaired (BVI) with their surroundings. However, reading remains an area where the potential of these technologies is not fully utilized. This work presents preliminary studies for the design of a finger-wearable E-Braille device that will allow the BVI to read electronic documents as they would read any document in Braille. The proposed device is wearable on a single finger on of the distal and middle phalanges (dorsal side). The main elements of the device are electrotactile display and force sensor. The electrotactile display is an electric board containing a matrix of electrodes that sends current to the fingertip for stimulating the touch feeling of a particular Braille character. By sending a sequence of Braille characters to this board, information can be sent to the user of the device through the generated electrotactile feeling. The force sensor is used in a feedback control loop to maintain steady contact pressure between the fingertip and the display board throughout the reading process. The entire finger-wearable E-Braille tactile display device is composed of a housing that can be customized to individual users, a miniature dc motor, mechanical components, and main elements. The initial testing of the proposed device is underway. Preliminary results indicate that the device can provide tactile sensation similar to that of reading a Braille document. The initial assessment of the device usability is underway.