Recently, a variety of approaches have been proposed to simulate real objects using two tactile feedback at the same time.
However, the possible masking effect is hardly reported when providing two types of tactile feedback.
In this study, we investigate the masking effect of mechanical vibration on the perception of electrical vibration.
Measure the absolute threshold and difference threshold of electrical vibration according to the presence/absence of mechanical vibration, frequency and strength.
The absolute threshold of electrical vibration tends to increase in the form of a ramp function because of the intensity of the shielding stimulus (
Mechanical vibration)increased.
In particular, the shielding effect is more significant when the target and the frequency of the shielding stimulus are the same (
Increase to 13 db with 25 db SL masker).
In addition, the difference in the threshold (average of 1. 21u2009dB)
Due to the masking stimulus, there is no significant change when the sensory level intensity of the target stimulus fits Weber's law.
The results further show that electric vibration also contributes to the activation of the slow adaptation effect.
This study will provide important guidelines for the design of the tactile interface using a variety of tactile feedback.
From the design of tactile devices to virtual reality, the importance of tactile feedback has been recognized in various fields.
More specifically, with the spread of the touch screen, the tactile interaction on the touch surface has attracted great attention. based devices.
In order to convey meaningful tactile information on the touch surface, research has been actively carried out in various fields, including the development of actuators and sensors, psychological and physical research and rendering techniques.
In order to provide tactile feedback on the touch surface, the method of generating mechanical vibration using a vibrating tactile actuator has been widely used.
The theory and method of simulating surface texture by transferring vibration to a touch surface or tool (such as a stylus) is studied, and it turns out that mechanical vibration is one of the most effective ways to reproduce this texture.
As another way to provide tactile feedback on the touch surface, friction modulation methods based on the squeeze film effect or the principle of electrical vibration are also studied.
More specifically, electric vibration has been deeply studied and commercialized due to its potential for seamless integration with ordinary touch screensbased devices.
Electric vibration can increase the user's dynamic friction based on the static power perception generated between the sliding fingertip and the touch surface.
By adjusting the perceived friction, electrical vibration can simulate various surface textures or 3D shapes of real objects on the touch surface.
The usefulness of this tactile feedback has recently led to the development of a vibration tactile actuator with a thin and flexible form and an electrical vibration display;
Wearable electronics for the future.
As mentioned earlier, in various types of tactile information, the method of reproducing object theory on tactile surfaces is mainly considered.
However, most studies focus on copying a message (
Or shape.
With single tactile feedback (
Vibration friction).
In order to simulate a tactile response similar to when touching a real object, it is hoped to stimulate a variety of tactile factors at the same time.
In other words, joint use of multiple types of tactile feedback may be effective.
In this regard, some research groups have proposed two ways of tactile feedback (
Friction or side force)
Can be used at the same time.
By using two types of tactile feedback, they demonstrate the feasibility of simultaneous representation of shapes and textures and/or keys
Click on the feel and texture of the touch surface.
However, when the two tactile feedbacks are mixed together, human perception features are rarely considered.
In general, when two or more stimuli are provided together, the shielding effect (
Perception of one stimulus is affected by the presence of another stimulus)
Perception of stimuli works.
Even in different sensory forms, the masking effect appears in sight and hearing as well as in touch.
The shielding effect is usually checked by observing changes in the absolute threshold (
Absolute limit, AL)
And difference threshold (
Difference limit, DL)
According to the presence or absence of masking stimuli, the target is stimulated.
In tactile perception, by changing the position, frequency, intensity, stimulus-
Asynchronous, etc.
The effect of target and masking stimulation.
It is observed that when there is a masking stimulus, the absolute threshold of the stimulus intensity tends to rise and there is no masking stimulus.
When target stimuli and masking stimuli are provided at the same location, the masking effect on the absolute threshold is more prominent than when provided at different locations, or when the same sensory channel is stimulated, when different sensory channels are stimulated (
Panini and Fei
Parth Channel).
In addition, the absolute threshold increases as the frequency of target stimuli and masking stimuli becomes similar or the intensity of masking stimuli becomes stronger.
Although in some research work, the change trend of absolute threshold is similar, the change degree of absolute threshold is different due to shielding stimulation, according to the conditions of stimulation;
This was also observed in the differential threshold experiment.
To date, most studies have focused on the study of masking effects when providing target stimuli and masking stimuli through the same tactile feedback means.
However, the masking effect of different types of tactile feedback is rarely studied.
As mentioned earlier, the shielding effect is observed to be different according to the conditions of the stimulus;
Therefore, this should be taken into account, especially in the design of the tactile interface using the new tactile feedback combination.
In this study, we consider providing two completely different ways of tactile feedback at the same time, namely, electrical vibration (EV)
Mechanical Vibration (MV)
, To the bare fingertips sliding on the touch screen.
More specifically, as a first step, this study focuses on the perception of electrical vibration in the presence of mechanical vibration.
The main purpose is to study the change of the absolute threshold and difference threshold of electrical vibration when mechanical vibration is used as shielding stimulus.
To measure these thresholds, we built the hardware settings in a way that provides both electrical and mechanical vibration on the touch surface.
We then conducted three experiments with a group of participants to confirm the effect of mechanical vibration on the perception of electrical vibration.
All the experiments were carried out in an active touch.
First, in experiment 1, we study the absolute threshold of each electrical and mechanical vibration.
Then, in Experiment 2, when the mechanical vibration of various frequencies and strengths is used as the shielding stimulus, we measure the shielding absolute threshold of the electrical vibration.
The intensity of shielding stimulation is dB SL (
The level of feeling is SL;
Refers to the number of decibels above the absolute threshold)
, And calculated according to the absolute threshold of mechanical vibration revealed in experiment 1.
Finally, in Experiment 3, we measured the differential threshold of electrical vibration when there is/is no shielding stimulus.
In this case, the electrical vibration is provided at a constant strength, and its sensory level is based on the shielding threshold revealed in experiment 2.
Shielding stimuli are the same as those used in experiment 2.