JPH11150794A - Method and device for presenting touching feeling - Google Patents

Abstract

PROBLEM TO BE SOLVED: To virtually present various kinds of touching feelings by sticking plural fine magnets to the surface of a skin, electromagnetically stimulating each of them so as to stimulate the skin and then controlling the level and phase of electromagnetic driving at each fine magnet. SOLUTION: The fine magnets 2-1 to 2-4 are one-dimensionally arranged at prescribed intervals to be adhered onto the surface of a palm 1 and electromagnetic coils 3-1 to 3-4 are provided opposed to the magnets 2-1 to 2-4 and inserting a very small space. The coils 3-1 to 3-4 are independently driven and drive the magnets 2-1 to 2-4 to generate stimulation to the skin. Namely a driving pattern generating means alternately select-drive the sets of the electromagnetic coils 3-1 to 3-3 and 3-2 to 3-4 to virtually generate the moving feeling of a touching feeling position. Concerning the coils 3-1 to 3-4, the levels or the phases of driving patterns are different between the electromagnetic coil in a center part and that at its peripheral part. Thus a driving phase difference is controlled to change the propagating characteristic of stimulation to the deep layer of the skin.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technology for transmitting information using a tactile sensation, and a method for presenting a tactile sensation for stimulating a skin surface and arbitrarily virtually realizing a smooth or rough tactile sensation. And an apparatus.

[0002]

2. Description of the Related Art Numerous studies have been made on the technique of transmitting information to humans through the sense of touch as a means for supplementing handicap of eyes and ears, and particularly in recent years as a field of virtual reality. References 1, 2, 3]. They start with a display of the presence or absence of force and contact, and present a three-dimensional local shape or fine texture by a two-dimensional array of pins or vibrators [Ref. 4, 5, 6]. There are a wide variety of things, such as those that transmit slippage (Reference Document 7) and those that control the roughness of the surface by the squeezing effect of strong ultrasonic waves [Reference Document 8].

[0003] In any of these studies, however, it seems that a technique for presenting a tactile sensation and a tactile sensation that is indistinguishable from the actual situation has been considered to be a very difficult future task.

[0004] It is possible for human beings to discriminate differences in surface materials and very fine structures by their tactile sensations, and enormous variations in human identifiable tactile sensations can be targeted to the surface of any device. This is because it is almost impossible to experience the same material and fine shape by faithfully reproducing it. [References] [1] KBShimoga, "A Survey of Perceptual Feedbac
k Issue in DexterousTelemanipulation; Part I. Fing
er Force Feedback, "Proc. VRAIS '93, pp.263-270, 1
993. [2] KBShimoga, "A Survey of Perceptual Feedbac
k Issue in DexterousTelemanipulation; Part II., Fi
nger Force Feedback, "Proc. VRAIS '93, pp.271-279. [3] T. Yoshikawa and A. Nagura," A Touch and Force
Display System for Haptic Interface, Proc. 1997 IEE
E Int. Conf. Robotics and Automation, pp. 3018-302
4, 1997. [4] M. Shimojo, M. Shinohara and Y. Fukui, "Shape I
dentification Performance and Pin-matrix Density i
na 3 dimensional Tactile Display, Proc. 1997IEEE V
RAIS, pp.180-187, 1997. [5] Cohn MB, M. Lam and RSFearing, "Tactile F
eedback for Teleoperation, "Telemanipulator Techno
logy Conf., Proc. SPIE, Vol. 1833, pp. 15-16, 1992. [6] Y. Ikei, K. Wakamatsu and S. Fukuda, "Texture P
resentation by Vibratory Tactile Display, "1997 IE
EE VRAIS, pp.199-205, 1997. [7] RDHowe, "A Force-Reflecting Teleoperated H
and System for theStudy of Tactile Sensing in Prec
ision Manipulation, "Proc.1992 IEEE Int.Conf.Robot
ics and Automation, pp.1321-1326, 1992. [8] T. Watanabe and S. Fukui, "A Method for Contro
lling Tactile Sensation of Surface Roughness Using
Ultrasonic Vibration, "Proc. 1995 IEEE Int. Conf. R
obotics and Automation, pp.1134-1139, 1995.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to provide a method and an apparatus that can easily generate various tactile sensations with a single mechanism.

[0006]

Means for Solving the Problems In order to solve the above-mentioned problems, the present inventors analyzed the physical characteristics of human skin and the characteristics of tactile receptors, and analyzed the spatio-temporal distribution of stimulation to the skin surface. A method and an apparatus for presenting a tactile sensation based on the characteristics of the tactile sensation determined by considering the characteristics of the pattern are proposed.

FIG. 1 is a diagram illustrating the principle of the present invention. FIG.
1 is a palm, for example, a ball of the thumb.

2-1 to 2-4 are, for example, 1 mm × 2 mm ×
The micromagnets have a size of 0.5 mm, are arranged one-dimensionally at intervals of 2 mm, and are adhered to the surface of the palm 1. 3
Numerals -1 to 3-4 denote electromagnetic coils, which face the micromagnets 2-1 to 2-4, respectively, and are provided with a slight space between them. Each electromagnetic coil is independently driven and drives an opposing micromagnet to cause irritation to the skin. Although not shown, the four electromagnetic coils 3-1 to 3-4 are fixedly held in one block, and further provided with means for stably supporting the block on the palm.

Reference numeral 4 denotes a driver for driving the electromagnetic coils 3-1 to 3-4, respectively. Reference numeral 5 denotes a drive pattern generating means for instructing the driver 4 of a level and a phase necessary for driving each of the electromagnetic coils 3-1 to 3-4, and is constituted by, for example, a computer.

The driving pattern generating means 5 includes the electromagnetic coil 3
-1,3-2,3-3 and the electromagnetic coil 3-2,3-
By alternately selecting and driving a set of 3 and 3-4, a virtual sense of movement of the tactile position is generated. Also, with respect to the three selected electromagnetic coils, the level or phase of the driving pattern is different between the electromagnetic coil at the center and the electromagnetic coil at the periphery thereof.

[0011] By touching the object lightly, a human can perceive and identify various touch feelings such as fur, cloth, wood and metal surfaces. The sensations occur in both active and passive situations [Ref. 9] and are perceived as similar sensations in most parts of human skin. Here, such universal information obtained on the fine structure and material of the object surface is referred to as "tactile sensation", and is distinguished from the perception of reading braille and recognizing a macro shape.

Considering the stress transmission characteristics of the skin,
When stress is applied to the surface of the elastic body, the fine stress pattern on the surface is transmitted to the inside while blurring. In other words, the elastic body acts as a spatial low-pass filter for the surface stress distribution. If we assume that human skin is a semi-infinite homogeneous elastic body, its filtering characteristics are easily calculated. Now, it is assumed that homogeneous and isotropic elasticity satisfies a semi-infinite region z> 0 in an xyz space. The pressure distribution in a plane parallel to the surface at a certain depth z is represented by P
_z (k), and the pressure distribution on the surface is written as P (k). Where k is the wave vector _{k = (k x, k y} ). Then, P (k) and P _z (k) are connected as P _z (k) = P (k) exp (− | k | z) (1), and each frequency component is elastic. Exponentially decreases inside the body. The degree of the attenuation is sharper for higher frequency components. (Note that here "pressure"
The term "" is used to mean the sum of the three principal stress components. Each component of the stress tensor is generally written as a product of a function of k or lower order k and exp (− | k | z) [Ref.
1]. Next, the human skin structure shown in FIG. 2 will be examined based on equation (1). It is said that the surface receptor (Meissna body) and the deep receptor (Batini body) exist at a depth of about 0.7 mm and 2 mm from the skin surface, respectively, in the human palm. At this time, for example, a spatial frequency component having a wavelength of 2 mm (k = π [rad / mm]) in the stress pattern given to the skin surface has a depth z = 0.7 at which the surface receptor is arranged.
1/9 at [mm], 1/9 at depth z = 2 [mm]
Decays to 500. The 1 mm wavelength component attenuates to 1/81 even at the surface receptor depth. From the above, the following can be said. 1. Each skin mechanoreceptor is stimulated with a spatially low-pass filtered stress pattern of different characteristics depending on its depth. 2. Since the low-pass characteristic of the skin has an exponential attenuation characteristic, a frequency component finer than a wavelength of 1 mm is hardly transmitted to any receptor.

Here, the main factors that determine the human tactile sensation will be considered. Humans can easily identify very fine features of the surface by their tactile sensations. It is known that the difference in surface roughness of sandpaper made of micron-order particles can be distinguished from the feel of a finger. However, high spatial frequency components of the stress generated on the skin surface hardly reach the internal mechanoreceptors.
Therefore, it is considered that the excellent perception is brought about by detecting a spatial frequency component having a wavelength larger than several mm due to a stick-slip or a fingerprint. Then, since each receiver is arranged at a substantially constant depth for each type, the same type of receptor perceives the surface stress through a (spatial) reducing filter of the same characteristic, and the low level caused by stick-slip It is expected that the phase of the spatial frequency component does not preserve the fine geometric features of the target surface.

From the above considerations, the main factors that determine the tactile sensation due to the fine structure of the object surface are: (1) the temporal waveform of the stimulus perceived by each skin mechanoreceptor; and (2) the macroscopic vision on the skin surface. It can be inferred that there is only a spatial movement.

Factor (1) means that the detailed lateral distribution of the stimulus for the same mechanoreceptor has little effect on the tactile determination. The “time waveform” perceived by each skin mechanoreceptor is considered to include both a mechanical stimulus and a thermal stimulus, but the thermal stimulus is excluded in the present invention for simplicity.

In the configuration example of the present invention shown in FIG. 1, the mass of the micromagnet is about 0.006 g, and when the driving frequency is set to several hundred Hz or less, the mechanical impedance is smaller than the mechanical impedance of the skin surface. Is also small, the force applied to the skin is proportional to the coil current.

Here, assuming that the driving forces of the three minute magnets arranged one-dimensionally are f ₁ , f ₂ and f ₃ , the driving force f ₂ of one minute magnet at the center and the two small magnets at the periphery are determined. The in-phase driving mode in which the driving forces f ₁ and f ₃ are in-phase and the anti-phase driving mode in which the driving forces f ₁ and f ₃ are in the opposite phase will be described.

I) In-phase driving mode: (f ₁ (t), f ₂ (t), f ₃ (t)) = (1, 1, 1) f (t) (2) ii) Negative-phase driving mode: (f ₁ (t), f ₂ (t), f ₃ (t)) = (− 0.5,1, −0.5) f (t) (3) FIGS. shows the transfer characteristics of f _1, f _2, f ₃ stimulation in the drive mode and the reverse-phase drive mode.

In the in-phase driving mode shown in FIG.
Similar stimuli are transmitted to the surface and deep receptors. In the reverse-phase drive mode, the deep receiver receives less stress than the surface receiver.

Therefore, the three coils are expressed as (f ₁ , f ₂ , f ₃ ) = c (t) (1,1,1) + r (t) (− 0.5,1, −0.5) (4) Driving, c (t) + r (t) becomes a surface receptor,
c (t) is approximately given to the deep receptors and can selectively stimulate receptors at different depths. (However, in this device, (1) the applied force is only the vertical component, and (2) it is not possible to specify the stimulus to the receptor [Merkel tactile device and Ruffini terminal] located between the skin surface layer and the deep layer. In the case where the distance between the micromagnets is 2 mm as in the example of FIG. 1, the normal stress reaching the deep receptor (when calculated assuming an isotropic homogeneous elastic body) is shown in FIG. In the in-phase driving mode of FIG. 3 (a), the normal stress reaching the surface receptor is 75%.
% In the reverse-phase driving mode of FIG. 3B. (References)

[9] GDLamb, "Tactile Discrimination of Texture
d Surface: Psychophysical Performance Measure-ment
sin Humans, "J. Physiol. Vol. 338, pp. 551-565, 1983. [10] H. Shinoda, M. Uehara and S. Ando," A Tactile S
ensor Using Three-Dimensional Structure, "Proc.199
3 IEEE Int. Conf. Robotics and Automation, pp. 435-4
41, 1993. [11] SPTimoshenko and JNGoodier: "Theory of E
lasticity, "McGraw Hill, 1970.

[0021]

FIG. 4 shows an embodiment of a tactile sensation providing apparatus according to the present invention. In FIG. 4, 2-1 to 2-
4 is a micro magnet, 3-1 to 3-4 are electromagnetic coils, 4-1 to 4
4-4 is a driver, 6-1 to 6-4 are ports, 7-1 to
7-4 is a D / A converter, 8 is a CPU, 9 is a memory,
10 is a tactile sensation control program, and 11 is a drive pattern table.

In operation, the CPU 8 executes the tactile control program 10. The drive pattern table 11 stores, for each type of tactile sensation to be realized, a current pattern to be passed through the central and peripheral electromagnetic coils. The tactile sensation control program 10 performs drive pattern generation control for determining the type of tactile sensation and electromagnetic coil switching control for presenting a sense of stimulus movement. With drive pattern generation control,
At each timing, data of a current pattern necessary for driving each of the three continuous electromagnetic coils is read from the drive pattern table 11, and three electromagnetic coils to be driven at each timing are selected by the electromagnetic coil switching control. I do. The CPU 8 operates the ports (6-1 to 6-4) corresponding to the three electromagnetic coils thus selected.
Of the driving patterns are sequentially set to the three ports, and the current values set to those ports are converted into analog signals by D / A converters (three of 7-1 to 7-4). And the driver (3 of 4-1 to 4-4)
). Each driver supplies a current corresponding to the input analog signal to the electromagnetic coil to drive it.

FIG. 5 shows an example of the switching timing of the electromagnetic coil switching control. When a vibration stimulus is alternately applied to two distant points on the skin, it is known that the stimulus feels as if the stimulus has moved continuously between the two points. As shown in FIG. By switching the way of selecting three drive coils among the four coils at the time interval T, a continuous feeling of movement of the virtual object can be expressed.

A gap is provided between the end of each electromagnetic coil and the opposing micromagnet, but the size of the gap varies, and even when the same driving current is applied, a stimulus generated by micromagnets having different sizes of the gap is generated. The strength of the different. Therefore, it is necessary to compensate for variations before using the device. FIG. 6 shows a calibration method for compensating for variations in the air gap by adjusting the amplifier gain of each driver.

In FIG. 6, reference numeral 12 denotes four electromagnetic coils 3
A coil fixing device for integrally holding and fixing -1 to 3-4, and 13 is a vibrator for calibration. The calibration oscillator 13 is
It has a function of vibrating the entire coil fixing device 12 up and down. Reference numeral 4-1 denotes a driver, exemplarily showing an internal configuration. The other drivers 4-2 to 4-4 are not shown, but have the same internal configuration as 4-1. Driver 4-1
Is composed of a variable gain amplifier 14, a gain controller 15, a buffer amplifier 16, a preamplifier 17 with a gain of 1000 times, and switches 18 and 19. Reference numeral 20 denotes a signal source for generating a driving pattern. Switches 18 and 19 are connected to a side during calibration, and connected to b side during normal operation.

At the time of calibration, the vibrator 13 is driven to vibrate at a constant amplitude. Thereby, each of the electromagnetic coils 3-1 to 3-4
The size of the gap between the tip of each of the micro magnets 2-1 to 2-4 also changes periodically, and a voltage corresponding to the size of the gap at each tip is applied to each of the electromagnetic coils 3-1 to 3-4. Is induced. The voltage induced in the electromagnetic coil is amplified at a fixed magnification by a preamplifier 17 in each driver, and input to a variable gain amplifier 14. Here, in each driver, the gain controller 15 is adjusted so that the signal level of the output section A of the variable gain amplifier 14 becomes equal. Thereafter, when the switches 18 and 19 are switched to the b side, each driver 4-1
In Steps 4 to 4, compensation for variations in the gap is completed.

FIG. 7 shows an experimental example of providing a tactile sensation in the in-phase drive mode and the anti-phase drive mode. Four electromagnetic coils 3-
Three continuous electromagnetic coils 3-1 to 1-3-4
150 mA at the center electromagnetic coil 3-2 using 3-3
Of the electromagnetic coils 3-1 and 3-
3 was supplied with the amplitude of the opposite-phase sine wave current varied from 0 to 150 mA. The change in the drive current of the electromagnetic coils on both sides in the horizontal direction in FIG.
Hz, 100 Hz, and 200 Hz. When the value of the drive current of the electromagnetic coils 3-1 and 3-3 on both sides is close to 0 or close to 150 mA in the opposite phase, that is, when the stimulus approaches one point, the subject touches a vibrating body such as a speaker surface. I felt the same "vibration" as when I did. But,
When the negative-phase currents of the electromagnetic coils 3-1 and 3-3 were approximately half those of the central electromagnetic coil 3-2, a clear change in the touch was recognized. The stimulus was non-vibratory and felt localized near the skin surface, and the extent of the spread in the surface direction was ambiguous.

FIG. 8 shows an experimental example of the presentation of a tactile sensation in which a stimulus is moved in the lateral direction. Three of the four electromagnetic coils were switched and selected at time intervals T as shown in FIG. 5, and the selected three electromagnetic coils were driven in the opposite-phase drive mode to stimulate the thumb ball. The experiment was performed by changing the switching time T, the frequency of the carrier signal, and the amplitude of all the applied signals as sine waves. <1> Assuming that the vibration amplitude (150 [mA] for the center coil) is constant, the condition under which the stimulus moves continuously along the skin surface is found, and as a result, T is 200 to 300 [m].
s] indicates that continuous movement is felt. <2> When the driving frequency and the amplitude were changed at T = 0.5 [s] (the condition under which the subject felt continuous movement of the stimulus), as shown in FIG. 9, the vibration frequency was 30 Hz or less. At that time, the subject was found to feel as if an object with a smooth surface (rather than vibration) was moving over the skin. When a smooth object was felt, almost no vibration due to the frequency of the carrier signal was felt.

FIG. 10 shows an experimental example of providing a tactile sensation using a random phase signal. In this case, a band-limited signal having a random phase is applied to the coil instead of the sine wave.

All the stimuli are switched in the reverse-phase drive mode as shown in FIG. 1. Carrier signal: frequency section [f ₁ , f ₂ ] [Hz]
And uniform intensity, and the phase is random. The effective value of the current in the center coil is 70 [mA]. 2. It is assumed that the signal switching time T is 0.5 [s].

As a result, as shown in the table of FIG. 10B, the upper limit frequency f ₂ of the frequency section is 200 Hz.
At the following times, the subject felt as if he was holding his hand with a sponge used in the kitchen as shown in FIG.

When f ₂ exceeds 200 Hz, the subject feels vibration, and cannot express the sense by comparing it with a real tactile sensation. The symbol of the item of "similarity" in the table of FIG. 10B indicates that the feeling is similar when the symbol is the same. These results indicate that the touch is strongly dependent on the upper limit f ₂ of the frequency.

FIG. 11 shows an experimental example of tactile sensation presentation using a pulse train. In this experiment, a pulse train signal is given in the opposite-phase driving mode as in the previous experiment, and switching is performed as shown in FIG. 1. Carrier signal: Each pulse has a width of 3 [ms] and is randomly generated at an occurrence frequency f [pluse / s].

The peak current of the pulse applied to the center coil is a random value in [150, 300] [mA]. 2. It is assumed that the signal switching time T is 0.5 [s].

As a result, as shown in FIG.
When the occurrence frequency f is about 30 [pulsc / s], the subject is lightly stroked on the palm with a thin and sharp pin-shaped object such as a pencil lead as shown in FIG. He felt that he felt like moving while being caught in.

When the frequency of occurrence of the pulse was too high or too low, the subject could not express it by comparing it with a daily tactile sensation. In the above description, four micromagnets and four electromagnetic coils are used in a one-dimensional array, but the present invention is not limited to this. Any number of micromagnets and a corresponding number of electromagnetic magnets may be used. The coils can be used in a one-dimensional or two-dimensional array.

[0037]

According to the present invention, the skin is stimulated by attaching a plurality of micromagnets to the skin surface and electromagnetically driving each of the micromagnets. Various feelings can be virtually given by a simple method of controlling.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating the principle of the present invention.

FIG. 2 is a sectional view of a human palm skin.

FIG. 3 is an explanatory diagram of stimulus propagation in an in-phase drive mode and an anti-phase drive mode.

FIG. 4 is a configuration diagram of an embodiment of a tactile sensation providing device according to the present invention.

FIG. 5 is a timing chart of switching electromagnetic coils.

FIG. 6 is an explanatory diagram of a method for calibrating stimulus intensity.

FIG. 7 is an explanatory diagram of a tactile sensation presentation example in an in-phase drive mode and an anti-phase drive mode.

FIG. 8 is an explanatory diagram of a stimulus movement feeling presentation example.

FIG. 9 is an explanatory diagram of a presentation example of movement due to changes in drive frequency and amplitude.

FIG. 10 is an explanatory diagram of a tactile sensation presentation example using a random phase signal.

FIG. 11 is an explanatory diagram of a tactile sensation presentation example by a pulse.

[Explanation of symbols]

 1: palm 2-1 to 2-4: micro magnet 3-1 to 3-4: electromagnetic coil 4: driver 5: drive pattern generating means

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[Procedure amendment]

[Submission date] November 27, 1997

[Procedure amendment 1]

[Document name to be amended] Drawing

[Correction target item name] All figures

[Correction method] Change

[Correction contents]

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FIG. 2

FIG. 3

FIG. 4

FIG. 5

FIG. 6

FIG. 7

FIG. 8

FIG. 9

FIG. 10

FIG. 11

Claims (3)

[Claims] 1. A plurality of stimulus applying means, each of which is independently driven, is disposed on the skin surface in a one-dimensional or two-dimensional manner in close proximity to each other. A tactile sensation presentation method characterized by obtaining a required tactile sensation by controlling a phase difference and changing a propagation characteristic of a stimulus to a deep skin layer. 2. The stimulus applying means according to claim 1, wherein each of the stimulus applying means comprises a micromagnet attached to the skin surface and an electromagnetic coil provided to face the micromagnet. A tactile sensation presentation method, which is performed using a phase of a driving current. 3. A plurality of stimulating means arranged one-dimensionally or two-dimensionally on the skin surface, each of which is independently driven, and a stimulating means for driving each of the stimulating means. And driving pattern generating means for generating a driving signal of a predetermined pattern for each driving means, wherein the generated driving signal pattern is a predetermined pattern for a continuous stimulating means. A tactile sensation providing device including a device that generates a driving phase difference.