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The aim of our work is to design a touch screen for displaying vibrotactile haptic feedback to the user via piezo patches attached to its surface. One of the challenges in the design is the selection of appropriate boundary conditions and the piezo configurations (location and orientation) on the screen for achieving optimum performance within the...
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... first four mode shapes of the glass plate are also shown in Figure 4. The results obtained from ABAQUS are compared to the theoretical values [12] in Table 1. Since we aim to vibrate the glass plate at frequencies that are within the limits of human vibrotactile perception of 0.1-500 Hz [13], the third boundary condition was chosen for the further analysis. ...
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... Such mechanical simulation models of large TSDs incorporating vibrotactile actuators also allow us to extend one haptic rendering method to different materials and actuators and find ways of better localization. Finite element modeling of touch surfaces has been discussed with piezo actuators in [28], [29], [30], and [31]. These finite element-based studies focus on generating maximum vibration amplitude on the touch surface rather than localized vibrotactile feedback. ...
Touch screen devices have become ubiquitous in modern day-to-day lives. While smaller touchscreen devices provide enough user engagement with meaningful haptic feedback, large touch devices still lack meaningful haptic stimulation. Existing literature for large touch surface vibrotactile localization uses many actuators and conventional boundary conditions. Previous numerical studies on haptic localization do not address multi-frequency excitation. This research proposes a new spring-damper boundary condition for a large bar-type display. Subsequently, a mechanical model of the large touch bar surface with multiple-electrostatic vibration actuators is developed using material damping information with multi-frequency excitation. Simultaneously, an experimental setup is developed for validation of the developed model. An optimization technique to localize vibrotactile haptic rendering at multiple selected zones of the touch bar is proposed. It has been established that by varying frequencies of excitation of two electrostatic resonant actuators, localizable vibrotactile feedback can be generated across the length of the touch bar. The experimental results corroborate the simulation results. Finally, the proposed optimization strategy for multi-zone vibrotactile rendering is experimentally verified.
... Haptic modules currently in place can generate effective vibrotactile feedback in devices with smaller touch screens [3]. The tactile sensation diminishes in strength for larger touchscreen displays as surface area increases [4]. Large touch screen displays find applications in a variety of areas such as digital musical instruments (DMIs), information kiosks, airports, restaurant chains, tablet computers, touch screen laptops / personal computers, vehicle infotainment systems, etc. [1,5]. ...
... Large touch screen displays find applications in a variety of areas such as digital musical instruments (DMIs), information kiosks, airports, restaurant chains, tablet computers, touch screen laptops / personal computers, vehicle infotainment systems, etc. [1,5]. However, vibrotactile feedback in large touchscreen devices is mostly absent owing to the lack of availability of actuators capable of generating vibration magnitudes for larger screens [3,4]. Moreover, with a given actuator capable of creating vibrotactile feedback on large touch screens, there is still a challenge to generate vibrations at specific places (localized vibrotactile feedback) on the screen. ...
In this research, modeling and analysis of a beam-type touchscreen interface with multiple actuators is considered. As thin beams, a mechanical model of a touch screen system is developed with embedded electrostatic actuators at different spatial locations. This discrete finite element-based model is developed to compute the analytical and numerical vibrotactile response due to multiple actuators excited with varying frequency and amplitude. The model is tested with spring-damper boundary conditions incorporating sinusoidal excitations in the human haptic range. An analytical solution is proposed to obtain the vibrotactile response of the touch surface for different frequencies of excitations, the number of actuators, actuator stiffness, and actuator positions. The effect of the mechanical properties of the touch surface on vibrotactile feedback provided to the user feedback is explored. Investigation of optimal location and number of actuators for a desired localized response, such as the magnitude of acceleration and variation in acceleration response for a desired zone on the interface, is carried out. It has been shown that a wide variety of localizable vibrotactile feedback can be generated on the touch surface using different frequencies of excitations, different actuator stiffness, number of actuators, and actuator positions. Having a mechanical model will facilitate simulation studies capable of incorporating more testing scenarios that may not be feasible to physically test.
... Haptic modules currently in place can generate effective vibrotactile feedback in devices with smaller touch screens [3]. The tactile sensation diminishes in strength for larger touchscreen displays as surface area increases [4]. Large touch screen displays find applications in a variety of areas such as digital musical instruments (DMIs), information kiosks, airports, restaurant chains, tablet computers, touch screen laptops / personal computers, vehicle infotainment systems, etc. [1,5]. ...
... Large touch screen displays find applications in a variety of areas such as digital musical instruments (DMIs), information kiosks, airports, restaurant chains, tablet computers, touch screen laptops / personal computers, vehicle infotainment systems, etc. [1,5]. However, vibrotactile feedback in large touchscreen devices is mostly absent owing to the lack of availability of actuators capable of generating vibration magnitudes for larger screens [3,4]. Moreover, with a given actuator capable of creating vibrotactile feedback on large touch screens, there is still a challenge to generate vibrations at specific places (localized vibrotactile feedback) on the screen. ...
In this research, modeling, and analysis of a beam-type touch screen interface with multiple actuators is considered. A mechanical model of a touch screen system, as thin beams, is developed with embedded electrostatic actuators at different spatial locations. This discrete finite element-based model is developed to compute the analytical and numerical vibrotactile response due to multiple actuators excited with varying frequency and amplitude. The model is tested with spring-damper boundary conditions incorporating sinusoidal excitations in the human haptic range. An analytical solution is proposed to obtain the vibrotactile response of the touch surface for different frequencies of excitations, number of actuators, actuator stiffness, and actuator positions. The effect of the mechanical properties of the touch surface on vibrotactile feedback provided to the user feedback is explored. Investigation of optimal location and number of actuators for a desired localized response, such as the magnitude of acceleration and variation in acceleration response for a desired zone on the interface, is carried out. It has been shown that a wide variety of localizable vibrotactile feedback can be generated on the touch surface using different frequencies of excitations, different actuator stiffness, number of actuators, and actuator positions. Having a mechanical model will facilitate simulation studies capable of incorporating more testing scenarios that may not be feasible to physically test.
... So far, various methods have been utilized to display tactile feedback on touch surfaces. Baylan et al. [2] simulated different layouts by conducting finite element analyses using the ABAQUS software and compared the amplitude of the vibrations on the touchscreen by placing a various number of piezoelectric actuators on different configurations. Then, they computed the first four resonant frequencies in three different boundary conditions of the touch screen to determine the optimal configuration for piezo patches. ...
... In our study, we also obtained the best results with a touch surface made of Gorilla Glass and glass substrates (see Table 3). Baylan et al. [2] studied the resonant frequencies of three different boundary conditions. They reported that fixing the touchscreen from four edges led to higher natural frequencies than other conditions similar to our findings (see Table 4). ...
... Piezoelectric actuators can provide different vibration waveforms. Therefore, several applications used piezoelectric actuators to create realistic tactile feedback [7,8]. In order to fully utilize the vibratory nature of piezoelectric actuators, the effects of the dimensions of a piezoelectric unimorph cantilever on the resonant frequencies need to be studied [9]. ...
The purpose of this study is to optimize the design of piezoelectric unimorph cantilevers, for ultra-thin keyboard design, so that the first resonant frequency is located in the sensitive frequency range and the first resonant amplitude is above the perception threshold of human hands for vibratory stimulus. The piezoelectric unimorphs used in this study have unequal active and passive areas. Simulations and experiments were first compared to find the effects of the dimensions on the first resonant frequency and displacement frequency response without collisions. A finite element model with collisions based on the verified boundary conditions was then built. Both the experiment data and simulation data was combined to build a regression model to predict the first resonant frequency with collisions for ultra-thin keyboard design. This study can help designers quickly design a vibrotactile device, in the early design stage.
... To be complete on UL devices, it may be noted that other institutes have worked on the analytic modeling and Finite Element Modeling of lamb wave propagation in resonator to induce friction control [51] [52] [53] [54] [55]. ...
The last few years have seen the emergence of ubiquitous mobile devices and tactile interfaces. These devices take an ever-important place in our daily life, they are present in our home, office, cars and even pockets. The abundance of these novel interfaces raised the interest in touch-based human-machine interactions and highlighted the problem of the lack of natural touch feedback in the existing generation of tactile displays. Today’s smartphones all possess basic haptic feedback thanks to low frequency vibrations. However, these vibrations are far from the natural touch sensation of a surface. The search for a better tactile feedback, closer to the natural human perception, is ongoing. Multiple solutions are being explored to deliver improved haptic feedback on existing mobile platforms such as smartphones or tablets. In this thesis, we investigate the tactile feedback thanks to ultrasonic lubrication, well adapted to touch screen. This technology uses the creation of a resonating standing wave in a substrate to modulate in real time the friction perceived by user moving his finger on the resonator surface; the principle is effective even on a flat glass surface. By a series of experimental friction measures, the influence of the relevant parameters such as the vibration amplitude, the exploratory speed, the resonance frequency is highlighted. This analysis is used to build advanced tactile interfaces, based on ultrasonic friction modulation. The control and the supply of the tactile interfaces are also investigated, considering the issues of integration and industrialization of the process. Finally, these new interfaces are used to explore advanced control methods, improving further the quality and reliability of the generated sensation. Psychophysical analysis is performed to fulfil the specifications of these devices on a perceptual point of view.
Recorded high-resolution texture vibration contains perceptually redundant spectral information due to tactile limitations of human skin. Also, accurate reproduction of recorded texture vibration is often infeasible for widely available haptic reproduction systems at mobile devices. Usually, haptic actuators can only reproduce narrow-bandwidth vibration. With the exception of research setups, rendering strategies need to be developed, that utilize the limited capabilities of various actuator systems and tactile receptors while minimizing a negative impact on perceived quality of reproduction. Therefore, the aim of this study is to substitute recorded texture vibrations with perceptually sufficient simple vibrations. Accordingly, similarity of band-limited noise, single sinusoid and amplitude-modulated signals on display are rated compared to real textures. Considering that low and high frequency bands of noise signals might be implausible and redundant, different combinations of cut-off frequencies are applied to noise vibrations. Moreover, suitability of amplitude-modulation signals are tested for coarse textures in addition to single sinusoids because of their capability of creating pulse-like roughness sensation without too low frequencies. With the set of experiments, narrowest band noise vibration with frequencies between 90 Hz to 400 Hz is determined according to the fine textures. Furthermore, AM vibrations are found to be more congruent than single sinusoids to reproduce too coarse textures.
A variable-friction tactile display (VFTD) is a haptic device that can control the lateral friction on a fingertip touching and exploring the tactile display. An adjustable friction can be induced by the ultrasonic flexural standing waves producing the squeeze-film effect on a thin tactile plate. Because the reduction in lateral friction monotonically increases as the amplitude of vibration increases, the topology of the friction coefficient on the VFTD surface resembles the level surface of vibration amplitude on the same surface. Hence the existence of stationary nodal lines limits the use of the entire surface as a tactile display. This paper presents an isofrequency mode switching technique between the two-fold degenerate vibration modes to prevent a user’s finger as much as possible from moving across or along the nodal lines. The finite element simulations had been conducted to design a VFTD prototype and to determine its free vibration characteristics. The simulations also helped to predict the availability of dual or multiple degenerate mode shapes at certain resonance frequencies. The computational results were verified by the experimental results with the measured resonance frequencies and corresponding nodal line configurations. The proposed mode switching techniques may contribute to the advancement of haptic displays utilizing squeeze-film damping effects.
