Optical tactile sensor and tactile measurement system

Abstract

An optical tactile sensor (100) comprises: light-emitting units (10, 11, 12, 20, 21, 22) that are disposed on one of the back surface and the side surface of a person's finger (300) and that emit light; a light-receiving unit (30) that is disposed on the other of the back surface and the side surface of the finger (300) and that receives light; and a haptic data calculation unit (270) that calculates a pressure corresponding to the deformation of the finger (300) on the basis of light that has travelled from the light-receiving unit (30), passed through the finger (300), and reached the light-receiving unit (30).

Description

Optical tactile sensor and tactile measurement system

[0001] The present invention relates to an optical tactile sensor and a tactile measurement system.

[0002] In recent years, sensors have been developed that measure contact force and estimate the contact direction of a fingertip by attaching a device to the palm, nail, or finger (see, for example, Patent Documents 1 and 2 and Non-Patent Documents 3 and 4).

[0003] The abstract of Patent Document 1 states that "the motion detection sensor detects finger motion, and comprises a base portion located above the finger when worn, a pair of arms extending from both sides of the base portion to the sides of the finger and clamping the sides of the finger, an acceleration sensor disposed on the base portion for detecting the acceleration of the finger during finger motion, and a strain gauge disposed on the arm portion for measuring strain generated in the arm portion due to deformation of the finger during finger motion."

[0004] Furthermore, the abstract of Patent Document 2 states that "In the system, the finger-worn device includes one or more finger-worn units. Each finger-worn unit has a body that functions as a support structure for components such as force sensors, accelerometers, and other sensors, as well as a haptic output device. The body has a sidewall portion coupled to a portion that rests adjacent to the user's fingernail, and an adjustable structure such as a sliding body portion formed from a deformable material such as metal, or coupled to each other using magnetic attraction, a spring, or other structure. The body of each finger-worn unit has a U-shaped cross-sectional outline that exposes the pad of each finger when coupled to the user's fingertip. A control circuit uses sensors to collect finger pressure input, lateral finger movement input, and finger tap input, and provides haptic output using the haptic output device."

[0005] Furthermore, a reference translation of the abstract of Non-Patent Document 3 states, "The purpose of this research is to measure the magnitude and direction of fingertip contact force without using a sensor between the object surface and the fingerpad. The authors focused on the fact that by measuring the color distribution of the nail surface using an optical sensor on the nail, various parts of the nail change from red to white depending on the magnitude and direction of force applied to the fingertip. This paper proposes a method for estimating the direction of fingertip force. First, the color measurement area for estimating direction from the nail color distribution image is determined by applying force horizontally to the contact surface of the fingertip. Next, a set of LED and photodiode is used to shine light on the specified location. From the distribution of change in nail color, the direction of fingertip contact force is estimated using the results of primary calibration of the relationship between color distribution and force direction."

[0006] Furthermore, the JST reference translation of the abstract of Non-Patent Document 4 states, "We have fabricated and experimentally evaluated a prototype wearable device that measures skin deformation at the fingertip when the finger comes into contact with an object. The device was attached to the fingertip, and a multiple photoreflection sensor (PRS) was used to measure the distance from the PRS to the side of the fingertip. The sensor did not contact the contact surface between the fingertip and the object. As a result, the contact force is obtained without changing the user's tactile sensation. Furthermore, the accuracy of the estimated contact force was improved by determining the fingertip posture by measuring the distance between the fingertip and the contact surface. Based on the prototype device, we implemented a system for estimating three-dimensional contact forces on the fingertip."

[0007] JP 2021-093174 JP 2013-003782 Hironobu Mameno, Masataka Imura, Yuki Uranishi, Shunsuke Yoshimoto1, and Osamu Oshiro. "Estimation of fingertip contact force direction based on change in nail color distribution", Biomedical Engineering, Vol. 52, 2014, pp. O-155- O-156 Ayane Saito, Wakaba Kuno, Wataru Kawai, Natsuki Miyata, and Yuta Sugiura. "Estimation of Fingertip Contact Force by Measuring Skin Deformation and Posture with Photo-reflective Sensors", ACM Proceedings, AH2019, 2019, pp. 1-6

[0008] The finger-worn device described in Patent Document 1 and the motion detection sensor described in Patent Document 2 have a large number of components, which may lead to a complicated structure and increased costs. There is also a risk that the device or sensor may become detached during measurement.

[0009] The device described in Non-Patent Document 3 has the risk of variations in detection results depending on the size and rigidity of the nail, and the risk of detection accuracy being reduced by coloring materials such as nail polish. Furthermore, while this device can detect strong forces with high accuracy, there is a risk of accuracy being reduced with weak pressure because the strain generated in the nail is small. Therefore, it is difficult to measure the pressure applied to the finger with high accuracy, regardless of the magnitude of the pressing force.

[0010] The device described in Non-Patent Document 4 uses a photoreflector as an optical sensor, and since there is a space between the sensor and the finger, it is susceptible to external influences such as external light. Furthermore, since this device is wearable, it requires a device that is sized to fit the finger. Furthermore, Patent Documents 1 and 2 and Non-Patent Documents 3 and 4 may limit the location where the device can be worn to a specific location.

[0011] Therefore, an object of the present invention is to measure finger pressure by easily attaching a device to a user's finger or hand without interfering with the user's sense of touch.

[0012] That is, the above-mentioned object of the present invention is achieved by the following configuration: (1) An optical tactile sensor comprising: a light-emitting unit disposed on one of the back and side surfaces of a person's finger and emitting light, a light-receiving unit disposed on the other of the back and side surfaces of the finger and receiving the light, and a force-sense data calculation unit that calculates a pressure corresponding to deformation of the finger based on light that has passed from the light-emitting unit through the finger and reached the light-receiving unit. (2) The optical tactile sensor described in (1), wherein the light-emitting unit is disposed on one of the back and side surfaces of the person's finger, and the light-receiving unit is disposed on the other of the back and side surfaces of the finger, and the force-sense data calculation unit calculates a pressure corresponding to deformation of the left side of the finger based on light that has passed from the light-emitting unit through the left side of the finger and reached the light-receiving unit, and calculates a pressure corresponding to deformation of the right side of the finger based on light that has passed from the light-emitting unit through the right side of the finger and reached the light-receiving unit, and calculates a pressure direction of the finger based on the pressure on the left side of the finger and the pressure on the right side of the finger. (3) The optical tactile sensor according to (2), wherein the light-emitting units are arranged on the left and right sides of the finger, and the light-receiving unit is arranged on the back of the finger. (4) The optical tactile sensor according to (3), wherein the light-emitting unit arranged on the left side of the finger and the light-emitting unit arranged on the right side of the finger alternately emit light, and the force data calculation unit determines whether the light has passed through the left side of the finger or the light has passed through the right side of the finger depending on the timing of light reception by the light-receiving unit. (5) The optical tactile sensor according to (4), wherein the light-emitting unit arranged on the left side of the finger and the light-emitting unit arranged on the right side of the finger alternately emit light of different wavelengths at each position. (6) The optical tactile sensor according to (2), wherein the light-receiving units are arranged on the left and right sides of the finger, and the light-emitting unit is arranged on the back of the finger. (7) The optical tactile sensor according to (6), wherein the light-emitting unit is always lit. (8) The optical tactile sensor described in (3), wherein the light-emitting unit is arranged on the fingertip side and front side of the left side of the finger and the fingertip side and front side of the right side of the finger, and the light-receiving unit is arranged on the back side of the finger.(9) The optical tactile sensor described in (2), in which the light-receiving unit is arranged on the fingertip and front sides of the left side of the finger and the fingertip and front sides of the right side of the finger, and the light-emitting unit is arranged on the back side of the finger. (10) The optical tactile sensor described in (1), in which the force data calculation unit calculates pressure corresponding to the deformation of the finger by detecting a change in the intensity of transmitted light accompanying a change in the optical path length within the finger. (11) The optical tactile sensor described in (1), in which the force data calculation unit measures a change in color of the finger or the person's hand based on a change in color of light received by the light-receiving unit and calculates the pressure of the finger. (12) The optical tactile sensor described in (1), in which the light-emitting unit and the light-receiving unit are arranged on a flexible substrate. (13) The optical tactile sensor described in (12), in which the flexible substrate is attached and mounted to the back and side of the finger. (14) The optical tactile sensor according to (1), further comprising a bioinformation calculation unit that calculates one of a pulse wave, touch, or finger movement based on the light received by the light receiving unit. (15) The optical tactile sensor according to (14), wherein the force data calculation unit corrects the pressure of the finger based on the pulse wave data calculated by the bioinformation calculation unit. (16) A tactile measurement system comprising: an optical tactile sensor comprising: a light-emitting unit that is disposed on one of the back and side of a person's finger and emits light, and a light-receiving unit that is disposed on the other of the back and side of the finger and receives the light, and a force data calculation unit that calculates pressure corresponding to deformation of the finger based on light that has passed through the finger from the light-emitting unit and reached the light-receiving unit.

[0013] According to the present invention, the pressure of the finger can be measured by easily attaching the device to the finger or hand without interfering with the user's sense of touch.

[0014] 1 is an explanatory diagram illustrating an example of the configuration of an optical tactile sensor according to a first embodiment. FIG. 1 is an explanatory diagram illustrating a state in which an optical tactile sensor is placed on a finger. FIG. 2 is an explanatory diagram (top view) illustrating the top surface of the position where the light-emitting unit is placed on the finger. FIG. 3 is an explanatory diagram (side view) illustrating the side surface of the position where the light-emitting unit is placed on the finger. A cross-sectional view of a finger as seen from the front. A cross-sectional view showing the light path when the finger is not in contact with the base. A cross-sectional view showing the light path when the finger is in contact with the base in a vertical direction. A cross-sectional view showing the light path when the finger is in contact with the base in a lower left direction. A cross-sectional view showing the light path when the finger is in contact with the base in a lower right direction. A functional block diagram showing a tactile measurement system equipped with an optical tactile sensor. FIG. 2 is a graph showing the signal intensity acquired from the light-receiving unit by the data acquisition unit. A graph after the preprocessing unit has performed preprocessing on the signal. FIG. 3 is a graph showing the signal intensity when the force data processing unit extracts peaks for the force data of the left light-emitting unit and the force data of the right light-emitting unit. The analysis unit analyzed the signal strength of the force data from the left light-emitting element and the signal strength of the force data from the right light-emitting element, and analyzed the rightward and leftward pressures. This is a graph showing the relationship between pressure and pulse waveform based on the biological data acquired from the pre-processing unit.

[0015] The following describes in detail embodiments of the present invention. Note that the embodiments described below are examples for realizing the present invention, and should be appropriately modified or changed depending on the configuration of the device to which the present invention is applied and various conditions. Therefore, the present invention is not limited to the following embodiments. Furthermore, the present invention may be configured by appropriately combining parts of the embodiments described below. Note that the same components are given the same reference numerals, and descriptions thereof will be omitted as appropriate.

[0016] First Embodiment [Configuration of Optical Tactile Sensor] Fig. 1 is an explanatory diagram illustrating an example of the configuration of an optical tactile sensor according to the first embodiment. Fig. 2 is an explanatory diagram showing a state in which the optical tactile sensor is placed on a finger.

[0017] 1 and 2, the optical tactile sensor 100 according to the first embodiment is configured to include a flexible substrate 1, light-emitting units 10 and 20, a light-receiving unit 30, and a wiring cable 200. The light-emitting units 10 and 20 and the light-receiving unit 30 are mounted on the flexible substrate 1.

[0018] The flexible substrate 1 is a type of printed wiring board and is made of a thin insulating material (plastic film). The flexible substrate 1 is flexible and can be bent with a slight force. The flexible substrate 1 can be repeatedly deformed. Even when deformed, the flexible substrate 1 has the property of maintaining the electrical properties of the flexible substrate 1 and the conductors wired thereon in that shape.

[0019] The light-emitting unit 10 arranged on the left side includes a light-emitting unit 11 arranged on the fingertip side and a light-emitting unit 12 arranged on the front side. When there is no need to specify which of the light-emitting units 11 and 12 is used, it is simply referred to as the light-emitting unit 10. The light-emitting unit 10 is arranged on the left side of the finger 300 and emits light.

[0020] The light-emitting unit 20 arranged on the right side includes a light-emitting unit 21 arranged on the fingertip side and a light-emitting unit 22 arranged on the front side. When there is no need to specify which of the light-emitting units 21 and 22 is used, it is simply referred to as the light-emitting unit 20. The light-emitting unit 20 is arranged on the right side of the finger 300 and emits light.

[0021] The light-emitting units 10 and 20 are both configured, for example, by infrared light-emitting diodes (LEDs). The light-emitting units 10 and 20 can have the same configuration as light-emitting units, and only differ in their locations, as shown in FIG. 1. The light-emitting units 10 and 20 emit, for example, infrared light. This prevents the user from seeing unnecessary light.

[0022] The light-emitting units 11, 12, 21, and 22 alternately emit light. Then, the light-emitting units 11, 12, 21, and 22 identify which of the light-emitting units 11, 12, 21, and 22 has emitted light according to the timing of light reception by the light-receiving unit 30. Furthermore, the light-emitting units 11, 12, 21, and 22 may be configured to emit infrared light of different wavelengths, and the light-receiving unit 30 may be configured to receive an amount of infrared light of different wavelengths, and are not limited to this. Note that the light emitted by the light-emitting units 11, 12, 21, and 22 is not limited to infrared light, and may be visible light such as green, red, or blue.

[0023] The light receiving unit 30 is disposed on the back surface of the finger 300 and receives light emitted by the light emitting units 11, 12, 21, and 22. The light receiving unit 30 receives the light emitted by the light emitting units 11, 12, 21, and 22 and generates an electrical signal such as a current or a voltage in accordance with the received light. As shown in FIG. 2 , the light receiving unit 30 is disposed on the back surface of the finger 300, for example.

[0024] The wiring cable 200 sends light emission instructions from the outside (for example, the information processing device 290 described later in Figure 9) to the light-emitting units 11, 12, 21, and 22, acquires an electrical signal generated in response to light received by the light-receiving unit 30, and outputs the signal intensity of the electrical signal to the outside (for example, the information processing device 290 in Figure 9).

[0025] For example, the haptic data calculation unit 270 of the information processing device 290 can calculate pressure corresponding to deformation on the left side of the finger based on the amount of light that passes through the left side of the finger from the light-emitting units 11 and 12 and reaches the light-receiving unit 30. The haptic data calculation unit 270 can also calculate pressure corresponding to deformation on the right side of the finger based on the amount of light that passes through the right side of the finger from the light-emitting units 21 and 22 and reaches the light-receiving unit 30. The haptic data calculation unit 270 can also calculate pressure corresponding to deformation on the fingertip side based on the amount of light that passes through the fingertip side from the light-emitting units 11 and 21 and reaches the light-receiving unit 30. The haptic data calculation unit 270 can also calculate pressure corresponding to deformation on the front side of the finger based on the amount of light that passes through the front side of the finger from the light-emitting units 21 and 22 and reaches the light-receiving unit 30.

[0026] The force-sense data calculation unit 270 may be provided in the information processing device 290 or in the optical tactile sensor 100 .

[0027] 3A and 3B are explanatory diagrams showing positions where light-emitting units are placed on a finger. Fig. 3A is an explanatory diagram (top view) showing the top surface of the positions where light-emitting units 10 and 20 are placed on a finger 300. Fig. 3B is an explanatory diagram (side view) showing the side surface of the positions where light-emitting units 10 and 20 are placed on a finger 300.

[0028] 3A and 3B, finger 300 has a first joint 301, a second joint 302, and a third joint 303. Optical tactile sensors 100a and 100b are configured to include a light-emitting unit 10 including a single LED, a light-emitting unit 20 including a single LED, and a light-receiving unit 30.

[0029] In Fig. 3A, the optical tactile sensor 100a is disposed at the first joint 301. The optical tactile sensor 100b is disposed at the second joint 302. On the other hand, in Fig. 3B, the optical tactile sensor 100b is disposed at the second joint 302. Although not shown, the optical tactile sensor 100b can also be disposed at the third joint 303.

[0030] 4 is a cross-sectional view of the finger 300 as seen from the front side. As shown in FIG. 4, a bone 400 is located at approximately the center of the finger 300.

[0031] Here, a living body, which is a human body, transmits and absorbs light. Since the finger 300 is also a living body, the living tissue 310 transmits and absorbs light. Here, optical path 19 indicates the optical path from the light-emitting unit 10 to the light-receiving unit 30. Also, optical path 29 indicates the optical path from the light-emitting unit 20 to the light-receiving unit 30.

[0032] When the optical path 19, 29 has a long optical path length from the light-emitting unit 10, 20 to the light-receiving unit 30, the amount of light absorbed by the biological tissue 310 increases, resulting in a decrease in the amount of transmitted light. Therefore, if the optical path length of the optical path 19, 29 is long, the amount of transmitted light decreases, and the signal strength decreases. In addition to the optical path length of the optical path 19, 29, the amount of blood in the living body also affects the amount of transmitted light. When pressure is applied to the measurement site in the living body, the measurement site in the living body becomes ischemic and the amount of hemoglobin decreases. This reduces the amount of light absorbed.

[0033] 5 is a cross-sectional view showing the optical path when a finger is not in contact with the base. In FIG. 5, optical path 41 indicates the optical path from light-emitting unit 10 to light-receiving unit 30. Also, optical path 42 indicates the optical path from light-emitting unit 20 to light-receiving unit 30.

[0034] As shown in FIG. 5, the optical path 41 of light transmitted through the biological tissue 310 on the left side of the finger 300 and the optical path 42 of light transmitted through the biological tissue 310 on the right side of the finger 300 have approximately the same optical path length, and therefore the amount of light transmitted through the optical path 41 and the amount of light transmitted through the optical path 42 are also equal.

[0035] 6 is an explanatory diagram showing the optical path when a finger is in vertical contact with the base. In FIG. 6, the optical path from the light emitters 10 and 20 to the light receiver 30 changes depending on the magnitude of the force that the finger 300 applies to the base 210 in the vertical direction C. This shows that the signal intensity of the transmitted light that reaches the light receiver 30 changes.

[0036] By applying a force in the vertical direction C, the optical paths 51 and 52 in Fig. 6 have fewer portions blocked by the bone 400 than the optical paths 41 and 42 in Fig. 5 , and therefore the signal strength of the amount of light received by the light receiving unit 30 increases. Also, in Fig. 6 , the optical paths 51 and 52 have roughly the same optical path length, which indicates that the amount of light received by the light receiving unit 30 is also equal.

[0037] 7 is an explanatory diagram showing the amount of light when a finger is in contact with the base 210 in a lower left direction. In FIG. 7, the light path from the light emitters 10 and 20 to the light receiver 30 changes depending on the magnitude of the force that the finger 300 applies to the base 210 in the lower left direction L. This shows that the signal intensity of the transmitted light that reaches the light receiver 30 changes.

[0038] That is, optical path 61 in Figure 7 is shorter than optical path 62 and has a smaller portion blocked by bone 400. In other words, because force is applied to the left side, optical path 61 is shorter than optical path 62 on the right side where no force is applied, causing ischemia on the left side of the finger, which is the measurement site, and a smaller portion blocked by bone 400. When the measurement site becomes ischemic, the amount of hemoglobin in optical path 61 decreases, and the light absorption rate of optical path 61 decreases. As a result, the signal intensity of transmitted light reaching light receiving unit 30 from light emitter 10 via optical path 61 is greater than the signal intensity of transmitted light reaching light receiving unit 30 from light emitter 20 via optical path 62.

[0039] 8 is an explanatory diagram showing the amount of light when a finger is in contact with the base in a lower right direction. In Fig. 8, the light path from the light emitters 10 and 20 to the light receiver 30 changes depending on the magnitude of the force that the finger 300 applies to the base 210 in the lower right direction R. This shows that the signal intensity of the transmitted light that reaches the light receiver 30 changes.

[0040] That is, optical path 71 in Figure 8 is longer than optical path 72, and a larger portion of it is blocked by bone 400. In other words, because force is applied to the right side, optical path 72 is shorter than optical path 71 on the left side where no force is applied, causing ischemia on the right side of the finger, which is the measurement site, and a smaller portion of it is blocked by bone 400. When the measurement site becomes ischemic, the amount of hemoglobin in optical path 72 decreases, and the light absorption rate of optical path 72 decreases. As a result, the signal intensity of transmitted light reaching light receiving unit 30 from light emitter 10 via optical path 71 becomes smaller than the signal intensity of transmitted light reaching light receiving unit 30 from light emitter 20 via optical path 72.

[0041] In this embodiment, the optical tactile sensor 100 can include a force-sense data calculation unit 270, which will be described later. The force-sense data calculation unit 270 calculates pressure corresponding to deformation of the left side of the finger 300 based on light emitted by the left light-emitting unit 10, which passes through the left side of the finger 300, and reaches the light-receiving unit 30. The force-sense data calculation unit 270 also calculates pressure corresponding to deformation of the right side of the finger 300 based on light emitted by the right light-emitting unit 20, which passes through the right side of the finger 300, and reaches the light-receiving unit 30.

[0042] This allows the force sense data calculation section 270 to calculate the pressure direction of the user's finger 300 based on the pressure on the left side of the finger 300 and the pressure on the right side of the finger 300 .

[0043] [Configuration of Tactile Measurement System] Fig. 9 is a functional block diagram showing a tactile measurement system equipped with an optical tactile sensor. As shown in Fig. 9, the tactile measurement system 500 is equipped with an optical tactile sensor 100 and an information processing device 290.

[0044] In this embodiment, as an example, a form in which the force-sense data calculation unit 270 (described later) is mounted on the information processing device 290 will be described, but this embodiment is not limited to this. For example, the force-sense data calculation unit 270 may be mounted on the optical tactile sensor 100.

[0045] The information processing device 290 is configured to include a data acquisition unit 220, a pre-processing unit 230, a force-sensory data processing unit 240, a biometric data processing unit 250, an analysis unit 260, a force-sensory data calculation unit 270, and a biometric data calculation unit 280.

[0046] The information processing device 290 is configured to include, for example, a central processing unit (CPU), a read-only memory (ROM), a random access memory (RAM), an external storage device, a display unit, etc. The external storage device is configured to include a predetermined tactile estimation program.

[0047] The CPU is a processing device that controls the entire information processing device 290. The ROM stores, for example, a control program that controls the information processing device 290. The RAM is configured, for example, by a DRAM (Dynamic Random Access Memory), and functions as a working memory that temporarily stores data necessary for the CPU to execute a predetermined program (for example, a tactile estimation program).

[0048] The external storage device is configured by, for example, a hard disk drive (HDD), and stores necessary data in association with each other.

[0049] The display unit is configured by a display device such as a liquid crystal display, an organic EL display, or a printer, or software for displaying (a viewer).

[0050] The CPU executes a predetermined program (tactile estimation program) stored in the ROM or an external storage device, thereby realizing a data acquisition unit 220, a preprocessing unit 230, a force-sense data processing unit 240, a biometric data processing unit 250, an analysis unit 260, a force-sense data calculation unit 270, and a biometric data calculation unit 280.

[0051] The data acquisition unit 220 alternately instructs the light-emitting units 10 and 20 of the optical tactile sensor 100 to emit light using their LEDs. This causes the light-emitting units 10 and 20 to emit light alternately. At the timing when the light-emitting units 10 and 20 alternately emit light, the light-receiving unit 30 receives the light emitted by the light-emitting units 10 and 20. The light-receiving unit 30 generates an electrical signal based on the amount of light received.

[0052] The following describes a method for evaluating the performance of the optical tactile sensor 100. The user applies pressure to their finger 300, for example, alternately in the right direction, left direction, and right direction for 10 seconds each, and the light receiving unit 30 measures the change in the signal strength of the electrical signal. As a result, the data acquiring unit 220 acquires from the light receiving unit 30 the signal strength of each electrical signal resulting from the movement of the user's finger 300, based on the light emitted by each of the light emitting units 10 and 20.

[0053] 10 is a graph showing the signal strength obtained by the data obtaining unit from the light receiving unit, where the horizontal axis represents time [sec] and the vertical axis represents signal strength [a.u].

[0054] 10, the data acquisition unit 220 of the information processing device 290 acquires the signal strength of each light-emitting unit 10, 20 from the light-receiving unit 30 based on the amplitude of the pulse. Specifically, a signal 600 shown in FIG. 10 indicates the signal strength of the light-emitting unit 20 (right side), and a signal 601 indicates the signal strength of the light-emitting unit 20 (left side).

[0055] 10 indicates that the user is pressing the right side of finger 300 against base 210 for 10 seconds from 0 [sec] to 10 [sec] and for each 10 second period from 20 [sec] to 30 [sec]. In contrast, signal 601 indicates that the user is pressing the left side of finger 300 against base 210 between 10 [sec] and 20 [sec].

[0056] Next, the pre-processing unit 230 performs pre-processing on the acquired signals 600 and 601 indicating the signal intensities. The pre-processing unit 230 removes noise from the signals 600 and 601 and separates them into biometric data and force data.

[0057] 11 is a graph showing the signal after the preprocessing by the preprocessing unit, where the horizontal axis represents time [sec] and the vertical axis represents signal strength [a.u].

[0058] 11 , the pre-processing unit 230 removes noise from a signal 600 indicating the signal strength of the light-emitting unit 20 (right side), and then separates the signal into a signal 610 indicating biometric data and a signal 700 indicating haptic data. Similarly, the pre-processing unit 230 removes noise from a signal 601 indicating the signal strength of the light-emitting unit 10 (left side), and then separates the signal into a signal indicating biometric data and a signal indicating haptic data.

[0059] The pre-processing unit 230 then transmits the separated haptic data to the haptic data processing unit 240 and also transmits the biometric data to the biometric data processing unit 250 .

[0060] Thereafter, the force-sense data processing unit 240 performs processing to detect peaks in each of the force-sense data separated by the pre-processing unit 230 .

[0061] 12 is a graph showing the signal strength at which the force sense data processor extracts peaks for the force sense data from the left light-emitting element and the force sense data from the right light-emitting element, where the horizontal axis represents time [sec] and the vertical axis represents signal strength [a.u].

[0062] The haptic data processing unit 240 performs, for example, first-order differentiation on a signal 700 of haptic data calculated from the amount of light reaching the light-receiving unit 30 from the light-emitting unit 10 on the left side and haptic data calculated from the amount of light reaching the light-receiving unit 30 from the light-emitting unit 20 on the right side. The haptic data processing unit 240 extracts peaks by performing first-order differentiation. Signal 800 in FIG. 12 indicates the signal strength of the haptic data calculated from the amount of light reaching the light-receiving unit 30 from the light-emitting unit 10, while signal 801 indicates the signal strength of the haptic data calculated from the amount of light reaching the light-receiving unit 30 from the light-emitting unit 20. FIG. 12 shows that the peaks of the signal strength occur at the timing of switching between left and right.

[0063] Next, the analysis unit 260 acquires the signal strength of the force sense data calculated from the amount of light reaching the light receiving unit 30 from the light emitting unit 10 where the peak was extracted, and the signal strength of the force sense data calculated from the amount of light reaching the light receiving unit 30 from the light emitting unit 20, in the force sense data processing unit 240, and analyzes the magnitude of the force (pressure) and the direction of pressure.

[0064] 13 shows the results of an analysis performed by the analysis unit on rightward and leftward pressures by analyzing the signal strength of the force sense data from the left light-emitting unit 20 and the signal strength of the force sense data from the right light-emitting unit 30. In FIG. 13, the horizontal axis represents the signal strength of the light reaching the light-receiving unit 30 from the right light-emitting unit 20, and the vertical axis represents the signal strength of the light reaching the light-receiving unit 30 from the left light-emitting unit 10.

[0065] As shown in Fig. 13, region 620 is a distribution of haptic data estimated by clustering for 10 seconds from 0 [sec] to 10 [sec] for signal 600 shown in Fig. 10. Region 621 is a distribution of haptic data estimated by clustering for 10 seconds from 10 [sec] to 20 [sec] for signal 601 shown in Fig. 10. Region 622 is a distribution of haptic data estimated by clustering for 10 seconds from 20 [sec] to 30 [sec] for signal 600 shown in Fig. 10.

[0066] As shown in FIG. 13, the analysis unit 260 can estimate from area 621 that the lower left of the finger 300 is pressing against the base 210, and can estimate from areas 620 and 622 that the lower right of the finger 300 is pressing against the base 210.

[0067] In this way, the analysis unit 260 analyzes the signal strength of the force sensory data calculated from the amount of light reaching the light receiving unit 30 from the light emitting unit 10 on the left side and the signal strength of the force sensory data calculated from the amount of light reaching the light receiving unit 30 from the light emitting unit 20 on the right side, and performs clustering to estimate the direction of pressure (pressure).

[0068] Furthermore, the biological data processing unit 250 calculates correction data for use in clustering in the analysis unit 260 from the relationship between pressure and pulse waveform based on the signal indicating the biological data processed by the preprocessing unit 230 .

[0069] Fig. 14 is a graph showing the relationship between pressure and pulse waveform based on biological data acquired from the pre-processing unit. In Fig. 14, the horizontal axis represents pressure and the vertical axis represents blood pressure.

[0070] The biometric data processor 250 generates correction data for correcting the force data based on the biometric data acquired from the preprocessor 230. Here, the pulse waveform refers to the amplitude and waveform shape of the pulse. Region 900 indicates the range of weak pressure. Region 901 indicates the range of standard pressure. Region 902 indicates the range of strong pressure.

[0071] The biometric data processor 250 acquires biometric data and calculates the average value of pressure. For example, the biometric data processor 250 has high sensitivity to signal strength in the weak pressure region 900, so by calculating the average value of pressure, it can estimate the pulse amplitude from the calculated average value. In addition, when the waveform shape disappears from the pulse waveform shape in Figure 14, the biometric data processor 250 can estimate that the pressure is in the strong pressure region 902.

[0072] Therefore, by processing the amplitude and waveform shape of the acquired biometric data, the biometric data processing unit 250 can generate correction data when the analysis unit 260 analyzes the magnitude (pressure) and direction of pressure.

[0073] As a result, the analysis unit 260 can use the correction data generated by the biometric data processing unit 250 to analyze the signal strength of the force sense data, thereby analyzing the magnitude (pressure) and direction of pressure with high accuracy.

[0074] The force sense data calculation unit 270 calculates the magnitude and pressure direction of the force analyzed by the analysis unit 260 and outputs them to a display unit or the like.

[0075] That is, the force-sense data calculation unit 270 calculates pressure corresponding to deformation of the left side of the finger 300 based on light emitted by the left light-emitting unit 10, which passes through the left side of the back surface of the finger 300, and is received by the light-receiving unit 30. The force-sense data calculation unit 270 also calculates pressure corresponding to deformation of the right side of the finger 300 based on light emitted by the right light-emitting unit 20, which passes through the right side of the back surface of the finger 300, and is received by the light-receiving unit 30.

[0076] This allows the force sense data calculation section 270 to calculate the pressure direction of the user's finger 300 based on the deformation of the left side of the finger 300 and the deformation of the right side of the finger 300 .

[0077] The force-sense data calculation unit 270 may also calculate pressure according to deformation of the finger 300 by detecting a change in transmitted light intensity that accompanies a change in the optical path length within the finger 300. The force-sense data calculation unit 270 may also measure a change in color of the finger 300 or the person's hand based on a change in color of the light received by the light-receiving unit 30, and calculate the pressure and / or pressure direction of the finger 300.

[0078] As described above, the force sense data calculation unit 270 can be mounted on either the information processing device 290 or the optical tactile sensor 100. This allows the force sense data calculation unit 270 to calculate the pressure (applied pressure) according to the left and right deformation of the finger 300, as well as the direction of the applied pressure of the finger 300.

[0079] 14, the biological data processing unit 250 can output the relationship between pressure and pulse waveform based on the biological data acquired from the pre-processing unit 230. This allows the biological data calculation unit 280 to calculate at least one of the pulse wave, tactile sensation, and finger movement based on the light received by the light receiving unit 30.

[0080] The optical tactile sensor 100 may have the light-emitting unit 10 disposed on the back of the person's finger 300 and the two light-receiving units 30 disposed on both the left and right sides of the person's finger 300. This allows the light-emitting unit 10 to be constantly lit, allowing the left light-receiving unit 30 to detect light that has passed through the left side of the finger, and the right light-receiving unit 30 to detect light that has passed through the right side of the finger. Furthermore, by calculating pressure corresponding to deformation on the left side of the finger 300 and pressure corresponding to deformation on the right side of the finger 300, the pressure direction of the finger 300 can be calculated based on the pressure on the left side of the finger 300 and the pressure on the right side of the finger 300.

[0081] The light-emitting units 10 and 20 may be point light sources or surface light sources. The light-emitting units 10 and 20 may emit light of a single wavelength or multiple wavelengths. The light-receiving unit 30 may receive light at a point or surface.

[0082] The sensors in the comparative examples shown in the prior art documents use sensor measurement methods that focus only on skin deformation or color changes of the finger.In contrast, the optical tactile sensor 100 of the present invention irradiates light while following the living body, so it can measure skin deformation and changes in blood volume of the finger or other part of the body, thereby obtaining tactile and vital data.

[0083] Because the optical tactile sensor 100 of the present invention is made up of a flexible substrate 1, it can be attached to a living body and follow its shape. Therefore, unlike conventional devices that clamp the finger, the optical tactile sensor 100 of the present invention can be attached to areas that cannot be clamped, allowing measurements. Furthermore, the optical tactile sensor 100 of the present invention can detect weak pressure without impeding the sense of touch.

[0084] As described above, the optical tactile sensor 100 according to this embodiment is configured to include light-emitting units 10, 20 that are arranged on one of the back and side surfaces of a person's finger 300 and emit light, a light-receiving unit 30 that is arranged on the other of the back and side surfaces of the finger 300 and receives light, and a force data calculation unit 270 that calculates pressure corresponding to deformation of the finger 300 based on light that has passed through the finger 300 from the light-emitting units 10, 20 and reached the light-receiving unit 300.

[0085] With this configuration, the optical tactile sensor 100 has the light-emitting units 10 and 20 and the light-receiving unit 30 disposed on either the back or side of the human finger 300. The optical tactile sensor 100 can calculate, using the force data calculation unit 270, pressure corresponding to the deformation of the finger 300 based on light that has passed from the light-emitting units 10 and 20 through the finger 300 and reached the light-receiving unit 30.

[0086] As a result, the optical tactile sensor 100 according to the first embodiment can be easily attached to a user's finger or hand and can measure finger pressure without impeding the user's sense of touch.

[0087] Furthermore, in the optical tactile sensor 100 according to this embodiment, the light-emitting units 10 and 20 are disposed on one of the back surface and both side surfaces of the human finger 300, and the light-receiving unit 30 is disposed on the other of the back surface and both side surfaces of the finger 300. The force-sense data calculation unit 270 calculates pressure corresponding to deformation on the left side of the finger 300 based on light that has passed from the left light-emitting unit 10 through the left side of the finger 300 and reached the light-receiving unit 30. The force-sense data calculation unit 270 also calculates pressure corresponding to deformation on the right side of the finger 300 based on light that has passed from the right light-emitting unit 20 through the right side of the finger 300 and reached the light-receiving unit 30. As a result, the force-sense data calculation unit 270 calculates the pressure direction of the finger 300 based on the pressure on the left side of the finger 300 and the pressure on the right side of the finger 300.

[0088] With this configuration, the optical tactile sensor 100 according to this embodiment uses the force sense data calculation unit 270 to calculate pressure corresponding to deformation on the right and left sides based on the light transmitted through the finger 300 for each of the light-emitting units 10, 20. This allows the optical tactile sensor 100 according to this embodiment to use the force sense data calculation unit 270 to calculate the pressure direction of the finger 300 based on the difference in pressure between the left and right sides.

[0089] In the optical tactile sensor 100 according to this embodiment, the light-emitting units 10 and 20 may be arranged on the left and right sides of the finger 300 , and the light-receiving unit 30 may be arranged on the back of the finger 300 .

[0090] With this configuration, the optical tactile sensor 100 according to this embodiment can be easily attached to a user's finger or hand without impeding the user's sense of touch, and can measure finger pressure.

[0091] Furthermore, in the optical tactile sensor 100 according to this embodiment, the light-emitting units 11 and 12 arranged on the left side of the finger 300 and the light-emitting units 21 and 22 arranged on the right side of the finger 300 emit light alternately, and the force-sense data calculation unit 270 may determine whether the light has passed through the left side of the finger 300 or the light has passed through the right side of the finger 300 depending on the timing of light reception by the light-receiving unit 30.

[0092] With this configuration, the optical tactile sensor 100 according to this embodiment can alternately calculate the pressure corresponding to the deformation on the left side and the pressure corresponding to the deformation on the right side using the force data calculation unit 270. This allows the optical tactile sensor 100 according to this embodiment to calculate the pressure direction of the finger 300 based on the difference between the left and right pressures.

[0093] Furthermore, in the optical tactile sensor 100 according to this embodiment, the light-emitting unit 10 arranged on the left side of the finger 300 and the light-emitting unit 20 arranged on the right side of the finger 300 may alternately emit light of different wavelengths at each position. For example, as shown in FIG. 1 , the light-emitting units 11 and 12 arranged on the left side of the finger 300 may alternately emit light of a first wavelength and light of a second wavelength. Furthermore, the light-emitting units 21 and 22 arranged on the right side of the finger 300 may alternately emit light of the first wavelength and light of the second wavelength. In this case, the light-emitting units 11, 12, 21, and 22 are controlled to, for example, light up one at a time in order to avoid mixing of light of the same wavelength.

[0094] Light of different wavelengths penetrates different depths into a living body. This allows the optical tactile sensor 100 to obtain data separately from the surface of a living body and from deep within the living body by alternately emitting light of different wavelengths at the same position.

[0095] Furthermore, in the optical tactile sensor 100 according to this embodiment, the light receiving units 30 may be arranged on the left and right sides of the finger 300, and the light emitting units 10 and 20 may be arranged on the back of the finger 300.

[0096] With this configuration, the optical tactile sensor 100 of this embodiment can measure the light path inside a living body even if the positions of the light-emitting units 10, 20 and the light-receiving unit 30 are changed, thereby increasing the freedom of placement location.

[0097] Furthermore, in the optical tactile sensor 100 according to this embodiment, the light-emitting units 10 and 20 may be constantly lit, allowing the optical tactile sensor 100 according to this embodiment to calculate pressure according to deformation based on data acquired in real time.

[0098] 3A and 3B, the light-emitting units 10 and 20 may be located on the fingertip and front sides of the left side of the finger 300 and on the fingertip and front sides of the right side of the finger 300. The light-receiving unit 30 may be located on the back of the finger 300.

[0099] With this configuration, the optical tactile sensor 100 according to this embodiment allows for selection of the placement of the light-emitting units 10, 20 and the light-receiving unit 30, thereby increasing the degree of freedom in placement locations.

[0100] Furthermore, in the optical tactile sensor 100 according to this embodiment, the light receiving unit 30 may be located on the tip and front sides of the left side of the finger 300, and on the tip and front sides of the right side of the finger. The light emitting units 10, 20 may be located on the back side of the finger 300. Similarly, the optical tactile sensor 100 according to this embodiment allows for selection of the locations of the light emitting units 10, 20 and the light receiving unit 30, thereby increasing the degree of freedom in the placement locations.

[0101] Furthermore, in the optical tactile sensor 100 according to this embodiment, the force data calculation unit 270 may calculate the pressure corresponding to the deformation of the finger 300 by detecting the change in the intensity of the transmitted light that accompanies the change in the optical path length within the finger 300.

[0102] With this configuration, the optical tactile sensor 100 according to this embodiment can convert the amount of light received by the light receiving unit 30 into an electrical signal and obtain the signal strength associated with changes in the optical path length. This allows the optical tactile sensor 100 according to this embodiment to detect changes in the intensity of transmitted light within the biological tissue 310, and therefore to calculate pressure from the signal strength based on changes in the intensity of transmitted light.

[0103] Furthermore, in the optical tactile sensor 100 according to this embodiment, the force data calculation unit 270 may measure the change in color of the finger 300 or the person's hand based on the change in color of the light received by the light receiving unit 30, and calculate the pressure of the finger 300.

[0104] With this configuration, the optical tactile sensor 100 can calculate pressure according to the change in color of the finger 300 or the person's hand by using, for example, a known non-contact three-dimensional strain measurement system to measure the change in color of the finger 300 or the person's hand in advance.

[0105] Furthermore, in the optical tactile sensor 100 according to this embodiment, the light-emitting units 10 and 20 and the light-receiving unit 30 may be disposed on the flexible substrate 1 .

[0106] With this configuration, the optical tactile sensor 100 according to this embodiment can be attached to fit the shape of the finger 300 or the shape of the nail by mounting the light-emitting units 10 and 20 and the light-receiving unit 30 on the flexible substrate 1. This allows the optical tactile sensor 100 to calculate the pressure of the finger 300 with greater accuracy.

[0107] Furthermore, in the optical tactile sensor 100 according to this embodiment, the flexible substrate 1 may be attached to the back and side surfaces of the finger 300 .

[0108] With this configuration, the optical tactile sensor 100 according to this embodiment does not have anything attached to the palm side, and therefore does not impede the user's sense of touch.

[0109] Furthermore, the optical tactile sensor 100 according to this embodiment may further include a biometric data calculation unit 280 that calculates at least one of pulse waves, touch, and finger movement based on the light received by the light receiving unit 30.

[0110] With this configuration, the optical tactile sensor 100 according to this embodiment can use the biological data calculation section 280 to calculate and output biological data such as pulse waves, touch, and finger movements.

[0111] Furthermore, in the optical tactile sensor 100 according to this embodiment, the force sense data calculation section 270 may correct the finger pressure based on the pulse wave data calculated by the biological data calculation section 280 .

[0112] With this configuration, the optical tactile sensor 100 of this embodiment can perform correction in the force data calculation unit 270 based on the pulse wave data calculated by the biological data calculation unit 280, thereby enabling pressure to be calculated with high accuracy.

[0113] Furthermore, the tactile measurement system 500 according to this embodiment may be configured to include an optical tactile sensor 100 and a force-sense data calculation unit 270. The optical tactile sensor 100 includes light-emitting units 10, 20 that are disposed on one of the back and side surfaces of a human finger 300 and emit light, and a light-receiving unit 30 that is disposed on the other of the back and side surfaces of the finger 300 and receives light. The force-sense data calculation unit 270 calculates pressure corresponding to the deformation of the finger 300 based on light that has passed through the finger 300 from the light-emitting units 10, 20 and reached the light-receiving unit 30.

[0114] With this configuration, the tactile measurement system 500 of this embodiment allows the optical tactile sensor 100 to be easily attached to the finger 300 or hand without interfering with the user's sense of touch, and can calculate pressure with high accuracy.

[0115] The optical tactile sensor of the present invention is suitably applicable to skin care technology, virtual reality devices, the medical field, sports technology, and the like.

[0116] REFERENCE SIGNS LIST 1 Flexible substrate 10, 11, 12 Light-emitting section (left side) 20, 21, 22 Light-emitting section (right side) 100 Optical tactile sensor 200 Wiring cable 210 Base 220 Data acquisition section 230 Preprocessing section 240 Force data processing section 250 Biometric data processing section 260 Analysis section 270 Force data calculation section 280 Biometric data calculation section (biometric information calculation section) 290 Information processing device 400 Bone 500 Tactile measurement system

Claims

1. An optical tactile sensor comprising: a light-emitting unit that is positioned on one of the back and side of a human finger and emits light; a light-receiving unit that is positioned on the other of the back and side of the finger and receives the light; and a force data calculation unit that calculates pressure corresponding to deformation of the finger based on light that has passed from the light-emitting unit through the finger and reached the light-receiving unit.

2. The optical tactile sensor of claim 1, wherein the light-emitting unit is located on one of the back and both sides of the person's finger, the light-receiving unit is located on the other of the back and both sides of the finger, and the force data calculation unit calculates a pressure corresponding to deformation of the left side of the finger based on light that has passed from the light-emitting unit through the left side of the finger and reached the light-receiving unit, and calculates a pressure corresponding to deformation of the right side of the finger based on light that has passed from the light-emitting unit through the right side of the finger and reached the light-receiving unit, and calculates a pressure direction of the finger based on the pressure on the left side of the finger and the pressure on the right side of the finger.

3. The optical tactile sensor according to claim 2, wherein the light-emitting units are arranged on the left and right sides of the finger, and the light-receiving units are arranged on the back of the finger.

4. The optical tactile sensor according to claim 3, wherein the light-emitting element arranged on the left side of the finger and the light-emitting element arranged on the right side of the finger alternately emit light, and the force data calculation unit determines whether the light has passed through the left side of the finger or the right side of the finger depending on the timing of light reception by the light-receiving element.

5. The optical tactile sensor according to claim 4, wherein the light-emitting unit arranged on the left side of the finger and the light-emitting unit arranged on the right side of the finger alternately emit light of different wavelengths at each position.

6. The optical tactile sensor according to claim 2, wherein the light receiving units are arranged on the left and right sides of the finger, and the light emitting unit is arranged on the back surface of the finger.

7. The optical tactile sensor according to claim 6, wherein the light emitting section is always lit.

8. The optical tactile sensor according to claim 3, wherein the light-emitting unit is arranged on the tip and front sides of the left side of the finger and the tip and front sides of the right side of the finger, and the light-receiving unit is arranged on the back side of the finger.

9. The optical tactile sensor according to claim 2, wherein the light receiving unit is located on the tip and front sides of the left side of the finger and the tip and front sides of the right side of the finger, and the light emitting unit is located on the back side of the finger.

10. The optical tactile sensor according to claim 1, wherein the force data calculation unit calculates pressure corresponding to deformation of the finger by detecting a change in the intensity of transmitted light that accompanies a change in the optical path length within the finger.

11. The optical tactile sensor according to claim 1, wherein the force data calculation unit measures the change in color of the finger or the person's hand based on the change in color of the light received by the light receiving unit, and calculates the pressure of the finger.

12. The optical tactile sensor according to claim 1, wherein the light-emitting section and the light-receiving section are arranged on a flexible substrate.

13. The optical tactile sensor according to claim 12, wherein the flexible substrate is attached to the back and sides of the finger.

14. The optical tactile sensor according to claim 1, further comprising a biometric information calculation unit that calculates one of pulse waves, tactile sensation, and finger movement based on the light received by the light receiving unit.

15. The optical tactile sensor according to claim 14, wherein the force data calculation unit corrects the finger pressure based on the pulse wave data calculated by the bioinformation calculation unit.

16. A tactile measurement system comprising: an optical tactile sensor comprising: a light-emitting unit that is positioned on one of the back and side of a human finger and emits light; and a light-receiving unit that is positioned on the other of the back and side of the finger and receives the light; and a force data calculation unit that calculates pressure corresponding to deformation of the finger based on light that has passed from the light-emitting unit through the finger and reached the light-receiving unit.

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