Tactile measurement device

Abstract

To provide a tactile sensation measurement device which can obtain information of a contact target from the state change of the vibration of a finger when a belly side of the finger contacts an object without obstructing the tactile sensation of the finger belly.SOLUTION: A tactile sensation measurement device according to the present invention comprises: a vibrator 10; a vibration detection sensor 20; a control unit 30 which controls the vibrator 10; and a measurement unit 40 which measures the state change of the vibration of the finger when a belly side of the finger contacts an object on the basis of the detection output of the vibration detection sensor 20. The vibrator 10 and the vibration detection sensor 20 are mounted on the back side of the finger 100 and used, and obtain information of a contact target from the state change of the vibration when the belly side of the finger 100 contacts the object on the basis of the measurement result of the measurement unit 40.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a tactile measurement device, and more particularly to a tactile measurement device that is worn on a user's finger to measure the tactile sensation of the finger pad. [Background technology]

[0002] The sense of touch is often involved in dexterous manipulations performed by humans with their hands. For example, we can manipulate pencils and toothpicks without visual cues, but it is difficult to do the same with a plastic finger cap. In other words, we manipulate objects by obtaining information about where we are holding them with our fingers and in what orientation through tactile sensation.

[0003] If the tactile sensations associated with such dexterous manipulations could be recorded and transmitted remotely, it would be possible to use the recording person as a proxy for the remote person, enabling remote work using tactile sensations. Furthermore, the act of recording the tactile sensations associated with dexterous manipulations could itself provide useful insights into the development of robots that enable such manipulations.

[0004] From this perspective, technology that measures the tactile sensation of the finger pad by attaching a device to a user's finger is important for recording and reproducing skills that use the fingertips. One example of this type of technology is the technology described in Non-Patent Document 1. Non-Patent Document 1 discloses a technology that detects how vibrations of a grasped object are transmitted and identifies the object itself. [Prior art documents] [Non-patent literature]

[0005] [Non-Patent Document 1] Seungjae Oh, Gyeore Yun, Chaeyong Park, Jinsoo Kim, and Seungmoon Choi. VibEye: Vibration-Mediated Object Recognition for Tangible Interactive Applications. CHI2019 Summary of the Invention [Problem to be solved by the invention]

[0006] The sensor described in Non-Patent Document 1 is a device that is worn on a finger in a manner that covers the entire finger and identifies an object by grasping the object, and is a device that detects the material of the grasped object by the way vibrations are transmitted rather than measuring the sense of touch. Furthermore, in the case of the sensor described in Non-Patent Document 1, because the sensor is worn in a manner that covers the finger pad, there is a problem in that the original sense of touch of the grasped object is impaired.

[0007] In response to this, various technologies have been proposed to measure nail color, nail distortion, or deformation of the finger's side surface. However, all of these technologies are limited to measuring the direction of applied force and are not capable of measuring the tactile sensation of the finger pad.

[0008] Therefore, an object of the present invention is to provide a tactile measurement device that can obtain information about a contact object from changes in the vibration state of a finger when the palm side (finger pad) of a finger comes into contact with an object, without inhibiting the tactile sensation of the finger pad. [Means for solving the problem]

[0009] The tactile measuring device of the present invention comprises: a vibrator; Detects at least one of axial acceleration and angular velocity around an axis The device includes a vibration detection sensor, a control unit that controls the vibrator, and a measurement unit that measures a change in the vibration state of the finger when the pad side of the finger comes into contact with an object based on the detection output of the vibration detection sensor. The vibrator and the vibration detection sensor are mounted on the dorsal side of the finger, and the measurement unit is based on the relationship between the changes in data in multiple directions obtained from vibration detection sensors. based on , contact Obtain information about the object being touched. [Effects of the Invention]

[0010] According to the present invention, it is possible to obtain information about a contact object from a change in the state of vibration of a finger when the pad of the finger comes into contact with an object, without inhibiting the tactile sensation of the finger pad. Problems, configurations, and effects other than those described above will become apparent from the following description of the preferred embodiment of the invention. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a configuration diagram conceptually showing an example of the configuration of a tactile measurement device according to an embodiment of the present invention; [Figure 2] 1 is a diagram showing an example of the configuration of a tactile measurement device according to an embodiment of the present invention mounted on a nail, viewed from the side, and illustrating axis definitions (ZY axes). FIG. [Figure 3] 1 is a diagram showing an example of the configuration of a tactile measurement device according to an embodiment of the present invention mounted on a nail, viewed obliquely from above, and illustrating axis definitions (X and Y axes). FIG. [Figure 4] FIG. 1 is a waveform diagram showing a Lissajous figure, which is a type of scatter diagram. [Figure 5] FIG. 1 is a diagram showing a Lissajous curve on an oscilloscope. [Figure 6] FIG. 2 is a diagram illustrating axis definitions of X, Y, and Z axes in a vibration detection sensor. [Figure 7] This is a scatter plot in which the angular velocity GX around the X axis and the angular velocity GY around the Y axis are plotted as a single graph when the finger is not touching anything. [Figure 8] FIG. 1 is a diagram showing an example of a scatter diagram (Lissajous figure). [Figure 9] FIG. 10 shows polar coordinates (r, θ) after transforming data points (xn, yn) of a scatter plot. [Figure 10] This is a scatter plot around the X and Y axes. [Figure 11] FIG. 10 is a diagram showing a data point O converted into polar coordinates (r, θ) and vector data P totaled for each Δθ. [Figure 12]FIG. 10 is an explanatory diagram illustrating generation of vector data. [Figure 13] FIG. 10 is a diagram showing an example of the correspondence between an oscillating figure (correct answer) and the obtained vector data. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In this specification and drawings, components having substantially the same functions or configurations are designated by the same reference numerals, and redundant explanations will be omitted.

[0013] <Tactile measuring device according to one embodiment of the present invention> Fig. 1 is a diagram conceptually illustrating an example of the configuration of a tactile measurement device according to one embodiment of the present invention. Fig. 1 illustrates a configuration diagram of a vibrator 10 and a vibration detection sensor 20 that constitute the tactile measurement device according to one embodiment of the present invention, mounted on the back of a finger 100, specifically on a nail 110, as viewed obliquely from above in front of the fingertip.

[0014] Fig. 2 shows a configuration example of a tactile measurement device according to an embodiment of the present invention mounted on a nail 110, viewed from the side, and the axis definition (ZY axis). Fig. 3 shows a configuration example of a tactile measurement device according to an embodiment of the present invention mounted on a nail 110, viewed from diagonally above, and the axis definition (XY axis).

[0015] [System configuration example] As the vibrator 10, it is preferable to use, for example, an eccentric vibrator in which an eccentric weight rotates. However, the vibrator 10 is not limited to an eccentric vibrator, and a linear vibrator such as a linear resonant actuator (LRA) can also be used. The following describes an example in which an eccentric vibrator is used as the vibrator 10. The vibrator 10 is attached to the nail 110 using double-sided tape, for example, strong double-sided tape for artificial nails.

[0016] It is preferable to use a six-degree-of-freedom sensor (acceleration and angular velocity sensor) that combines a three-axis acceleration sensor and a three-axis angular velocity sensor as the vibration detection sensor 20. However, the vibration detection sensor 20 is not limited to a six-degree-of-freedom sensor of acceleration and angular velocity, and a three-axis acceleration sensor or a three-axis angular velocity sensor can also be used. In the following, an example will be described in which a six-degree-of-freedom sensor (acceleration and angular velocity sensor) is used as the vibration detection sensor 20.

[0017] The vibrator 10 and the vibration detection sensor 20 are integrated, for example, by connecting the vibration detection sensor 20 onto the vibrator 10 with double-sided tape. Note that although the example shown here is one in which the vibration detection sensor 20 is connected onto the vibrator 10 with double-sided tape to integrate the two, it is also possible to provide the vibrator 10 and the vibration detection sensor 20 separated from each other on the nail 110. However, in order to mount the vibrator 10 on the nail 110, which has a small surface area, it is preferable to provide the vibrator 10 and the vibration detection sensor 20 as an integrated unit.

[0018] 1, the tactile measurement device according to this embodiment includes a control unit 30 and a measurement unit 40. The control unit 30 controls the vibration of the vibrator 10 by applying a constant voltage controlled by, for example, pulse width modulation (PWM) to the vibrator 10. This control by the control unit 30 causes the vibrator 10 to vibrate at, for example, about 100 Hz.

[0019] The measurement unit 40 measures a change in the vibration state of the finger 100 when the pad of the finger (finger pad) comes into contact with an object, based on the detection output of the vibration detection sensor 20. Based on the measurement results of the measurement unit 40, information on the contact object can be obtained from the change in the vibration state of the finger 100 when the finger pad comes into contact with an object (for example, how the vibration attenuates). Examples of the information on the contact object include the shape, contact force, and contact position of the contact object.

[0020] The control by the control unit 30 and the measurement by the measurement unit 40 can be configured to be performed using, for example, a microprocessor and a personal computer. In this case, I2C (Inter-Integrated Circuit) communication is performed between the vibration detection sensor 20 and the microprocessor, and acceleration in the X, Y, and Z axes and angular velocity around the X, Y, and Z axes are acquired at, for example, approximately 1.7 kHz. The personal computer communicates serially with the microprocessor and performs data acquisition, drawing, and calculations using a Python environment.

[0021] As described above, the tactile measurement device according to this embodiment is configured to mount the vibrator 10 and the vibration detection sensor 20 on the dorsal side of the finger 100 (on the nail 110 in this embodiment) and measure the behavior of the finger 100 when it vibrates due to excitation by the vibrator 10, specifically, the change in the vibration state of the finger 100. With this configuration, the vibrator 10 and the vibration detection sensor 20 are mounted on the nail 110, so that the tactile sense of the finger pad is not hindered. Therefore, with the tactile measurement device according to this embodiment, information about the contact object, specifically, the shape, contact force, and contact position of the contact object can be obtained (estimated) from the change in the vibration state of the finger 100 when the finger pad comes into contact with an object (for example, the manner in which the vibration of the finger 100 attenuates), without hindering the tactile sense of the finger pad.

[0022] More specifically, when the finger 100 touches an object while the vibrator 10 continues to vibrate the finger 100, the vibration state of the finger 100 changes. For example, when the finger 100 touches a convex portion while the finger 100 continues to vibrate, the convex portion inhibits the vibration of the finger 100, causing a change in the vibration state of the finger 100. By capturing this change in the vibration state of the finger 100 with the tactile measuring device according to this embodiment, the shape, contact force, and contact position of the contact object can be estimated.

[0023] [Example of measuring changes in finger vibration state] Next, a measurement example will be described in which a change in the vibration state of the finger 100 when vibrated by the vibrator 10 is measured, which is executed by a personal computer having the function of the measurement unit 40, for example.

[0024] (Drawing a scatter plot) By acquiring sensor signals from the vibrator 10 (a six-degree-of-freedom sensor in this embodiment) and plotting a scatter diagram for two of the signals, changes in the vibration state of the finger 100 can be measured. Since the signals are associated with rotational motion, ideally, the sensor values for each axis are sinusoidal, and the resulting scatter diagram is a Lissajous figure, which is a diagram drawn by (f(t), g(t)) when the two sinusoidal signals f(t) and g(t) are the coordinate values on the x-axis and y-axis. FIG. 4 shows a waveform diagram of a Lissajous figure, which is a type of scatter diagram, and FIG. 5 shows a Lissajous curve on an oscilloscope. By plotting a Lissajous figure for two signals, time information is lost, but the phase difference, intensity ratio (amplitude ratio), and other characteristics between the two signals can be clearly observed.

[0025] When a six-degree-of-freedom sensor (acceleration and angular velocity sensor) is used as the vibration detection sensor 20, the acceleration AX in the X-axis direction, the acceleration AY in the Y-axis direction, the acceleration AZ in the Z-axis direction, and the angular velocity GX around the X-axis, the angular velocity GY around the Y-axis, and the angular velocity GZ around the Z-axis are acquired by the vibration detection sensor 20. Fig. 6 shows the axis definitions of the X, Y, and Z axes in the vibration detection sensor 20.

[0026] The combinations of sensor values of the vibration detection sensor 20 are six types (six pairs): acceleration in the XY-axis direction, acceleration in the YZ-axis direction, acceleration in the ZX-axis direction, and angular velocity around the XY-axis, angular velocity around the YZ-axis, and angular velocity around the ZX-axis.

[0027] As mentioned above, ideally, the vibrations of each axis form a sine wave to draw a Lissajous figure. However, in reality, the figure is significantly distorted. As an example, in a Lissajous figure based on angular velocity around the X and Y axes, when the finger 100 is not in contact with anything, the Lissajous figure draws a shape close to an ellipse, and the angular velocity around the Y axis is greater than the angular velocity around the X axis. This is thought to be due to the inherent ease of rotation of the finger. In the following, although the vibrations of each axis are not sine waves, for convenience the scatter diagram that is drawn may be referred to as a Lissajous figure.

[0028] When an object (for example, the tip of a pair of scissors, the same applies hereinafter) is brought into contact with the pad of a finger, the ellipse of the Lissajous figure shrinks in the X-axis direction. Also, when an object is brought into contact with the tip of the finger 100, the ellipse of the Lissajous figure shrinks in the Y-axis direction. In other words, the change in the shape of this ellipse makes it possible to estimate the position in the front-to-back direction of the finger 100 where the object is in contact. Also, when the finger 100 is pressed hard against the object, the Lissajous figure becomes smaller overall. This phenomenon is thought to be due to better absorption of vibrations, and suggests that it is also possible to obtain information about the contact area or contact pressure.

[0029] Next, in the Lissajous figure due to acceleration around the ZX axis, when nothing is in contact with the finger 100, the Lissajous figure is close to an ellipse, and the acceleration around the X axis is greater than the acceleration around the Z axis. This is considered reasonable because the original vibration of the eccentric vibrator is on the XY plane. Furthermore, when an object is in contact with the side of the finger pad, the inclination of the ellipse changes depending on whether the contact position is left or right. In other words, this change in the shape of the ellipse makes it possible to estimate where in the left-right direction the object is in contact with the finger 100.

[0030] 7 shows a scatter diagram in which the angular velocity GX around the X axis and the angular velocity GY around the Y axis when the finger 100 is not in contact with anything are plotted as a single graph. As described above, the shape of this scatter diagram differs depending on the contact position of the object touching the finger 100 and the manner of touching. In other words, the shape of the Lissajous figure is completely different depending on the contact position of the finger 100 with the object, for example, between the pad and the tip.

[0031] (Analysis of Lissajous figures) Next, the process of finding so-called features from the drawn Lissajous figure is carried out, that is, the process of converting the figure centered at the origin (ideally an ellipse-like figure) into polar coordinates (r, θ). Specifically, the process of re-plotting the data for each point using the distance from the origin, i.e., the function r(θ), and the angle θ.

[0032] An example of a scatter diagram (Lissajous figure) is shown in Figure 8. n ,y n ) into polar coordinates (r n ,θ n ) to obtain the function r(θ) of the angle θ. n ,y n ) into polar coordinates (r n ,θ n ) is shown.

[0033] The number of data points in the scatter diagram is, for example, about 1000. As an example, by acquiring data 1700 times per second from the vibration detection sensor 20, the time required to acquire this data is about 0.6 seconds. The number of data points is not limited to about 1000 points, and may be, for example, about 100 points.

[0034] Predetermined angle range θ m ~θ m+1 The average or total value (either is fine) of the data points within the width Δθ is calculated by dividing the angle θ m For example, the data value at the angle θ m Divide into 36 (Δθ=10 degrees). Angle θ m The number of divisions is not limited to 36, and may be smaller than 36, although the subsequent calculation process will take longer as the number of data increases.

[0035] (Vector data generation) In this way, an amplitude function with the phase difference as a variable is derived from the Lissajous figure, and vector data is generated. Figures 10 and 11 show an example of actual vector data generation. Figure 10 is a scatter plot around the X and Y axes, and Figure 11 shows data points O converted to polar coordinates and vector data P totaled for each Δθ.

[0036] As mentioned above, when a six-degree-of-freedom sensor is used as the vibration detection sensor 20, the combinations of sensor values are six pairs (six types): acceleration in the XY-axis direction, acceleration in the YZ-axis direction, acceleration in the ZX-axis direction, and angular velocity around the XY-axis, angular velocity around the YZ-axis, and angular velocity around the ZX-axis.

[0037] Figure 12 is an explanatory diagram of vector data generation. All of the vector data obtained from the six pairs of scatter plots are connected to form one vector data. In the explanatory diagram of Figure 12, the graph (axay) with the vertical axis ax and the horizontal axis ay represents the acceleration in the X-axis direction and the acceleration in the Y-axis direction, and the graph (gzgy) with the vertical axis gz and the horizontal axis gx represents the angular velocity around the Z-axis and the angular velocity around the X-axis. Similarly, although not shown, "ayaz" is a graph of acceleration in the Y-axis direction and acceleration in the Z-axis direction, "azax" is a graph of acceleration in the Z-axis direction and acceleration in the X-axis direction, "gxgy" is a graph of angular velocity around the X-axis and angular velocity around the Y-axis, and "gygz" is a graph of angular velocity around the Y-axis and angular velocity around the Z-axis.

[0038] (Final estimation method) Next, a machine learning technique is used as a final estimation method for the shape, contact force, and contact position of the contact object, and machine learning is performed using the vector data. An example of the machine learning technique is a support vector machine (SVM). However, the machine learning technique is not limited to a support vector machine, and other estimation techniques such as a neural network may also be used.

[0039] Specifically, for example, a finger is placed in contact with three types of contacting figures, and the vector data obtained at that time, i.e., the vector data corresponding to the contacting figure (correct answer), is acquired. Machine learning is performed using the correspondence between this contacting figure (correct answer) and the acquired vector data. As an example, vector data is acquired five times for each contacting figure. Figure 13 shows an example of the correspondence between the contacting figure (correct answer) and the acquired vector data.

[0040] In this way, by executing the above-mentioned series of processes and completing the machine learning, it is possible to estimate the contact figure, specifically the shape of the contact object, the contact force, and the contact position, from the obtained vector data.

[0041] The present invention is not limited to the above-described embodiment, and various other applications and modifications are possible without departing from the spirit of the present invention as set forth in the claims. For example, the above-described embodiment describes the system configuration in detail and specifically to clearly explain the present invention, and is not necessarily limited to a system having all of the described configurations. Furthermore, it is also possible to add, delete, or replace part of the configuration of the present embodiment with other configurations.

[0042] Furthermore, in the above-described embodiment, the tactile measurement device of the present invention is mounted on the nail 110 of a human finger 100, but the application is not limited to a human finger 100 and can also be applied to a robot finger. In this case, the vibrator 10 and vibration detection sensor 20 that constitute the tactile measurement device of the present invention are mounted on the back of the robot finger. In this way, by applying it to a robot finger, the tactile measurement device of the present invention is useful for developing a robot that can perform operations that record tactile sensations related to dexterous manipulations. [Explanation of symbols]

[0043] 10... vibrator, 20... vibration detection sensor, 30... control unit, 40... measurement unit, 100... finger, 110... nail, AX... acceleration in the X-axis direction, AY... acceleration in the Y-axis direction, AX... acceleration in the Z-axis direction, GX... angular velocity around the X-axis, GY... angular velocity around the Y-axis, GZ... angular velocity around the X-axis

Claims

1. A vibrator and a vibration detection sensor that detects at least one of an axial acceleration and an angular velocity around an axis; a control unit that controls the vibrator; a measuring unit that measures a change in the state of vibration of the finger when the pad side of the finger comes into contact with an object based on the detection output of the vibration detection sensor; Equipped with the vibrator and the vibration detection sensor are mounted on the back of the finger, The measurement unit obtains information about the contact object based on a relationship between changes in data in multiple directions obtained from the vibration detection sensor. Tactile measurement device.

2. The information on the contact object includes the shape, contact force, and contact position of the contact object. The tactile measuring device according to claim 1 .

3. The vibrator is an eccentric vibrator or a linear vibrator that generates vibrations in multiple directions. The tactile measuring device according to claim 1 or 2.

4. The vibration detection sensor is a three-axis acceleration sensor, a three-axis angular velocity sensor, or a six-degree-of-freedom sensor. The tactile measuring device according to claim 1 or 2.

5. The control unit applies a voltage of a constant value that is pulse width modulated to the vibrator. The tactile measuring device according to claim 1 or 2.

6. The measurement unit associates the data measured by the vibration detection sensor with each other as a pair of two data, each of which is an acceleration in the axial direction of the vibration detection sensor or an angular velocity around the axis of the vibration detection sensor, and obtains information about the contact object based on the relationship between the two data. The tactile measuring device according to claim 1 or 2.

7. The measurement unit derives an amplitude function with the phase difference as a variable based on the relationship between the two data, and obtains information about the contact object based on the function. The tactile measuring device according to claim 6.

8. The measurement unit draws a scatter plot between the two data and derives an amplitude function with the phase difference as a variable from the scatter plot. The tactile measuring device according to claim 7.

9. The measurement unit generates vector data based on the function, and obtains information about the contact object based on the vector data. The tactile measuring device according to claim 7 or 8.

10. The measurement unit performs machine learning using the vector data. The tactile measuring device according to claim 9.

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