Patent Publication Number: US-2021182372-A1

Title: Method and apparatus for biometric authentication based on vibration signal

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     This application claims priority under 35 U.S.C. § 119 to Korean Patent Application Nos. 10-2019-0167601 filed on Dec. 16, 2019, and 10-2020-0141786 filed on Oct. 29, 2020, each of which is incorporated herein by reference in its entirety. 
     BACKGROUND OF THE INVENTION 
     1. Technical Field 
     Various embodiments relate to a method and apparatus for biometric authentication based on a vibration signal. 
     2. Description of the Related Art 
     As the protection of individual information recently becomes important, services that require a high security level through biometric recognition of a user, such as iris recognition, fingerprint recognition, and face recognition, are increased. An electronic device includes at least one sensor for biometric recognition, and collects biometric information based on an image though the sensor. Accordingly, in order for the electronic device to accurately obtain the biometric information, a user needs to take an intended act to gaze at the sensor or to bring a predetermined portion of his or her body accurately in contact with the sensor. For this reason, the user&#39;s convenience may be degraded. Furthermore, since the sensor needs to be installed on a surface of the electronic device, the electronic device requires an exposure space for the sensor and a degree of freedom of the design of the electronic device may be degraded. 
     SUMMARY OF THE INVENTION 
     Various embodiments provide an electronic device capable of efficiently performing biometric authentication on a user and an operating method thereof. 
     Various embodiments provide an electronic device capable of performing biometric authentication on a user without degrading user convenience, and an operating method thereof. 
     Various embodiments provide an electronic device capable of being reduced in size, securing a degree of freedom of the design of the electronic device, and performing biometric authentication on a user, and an operating method thereof. 
     In an aspect, an operating method of an electronic device may include outputting at least one vibration signal to at least one touched object through a vibration module, receiving at least one response signal for the vibration signal from the object through the vibration module, and performing biometric authentication on the object based on at least one of the vibration signal or the response signal. 
     In an aspect, an electronic device may include a vibration module and a processor connected to the vibration module and configured to authenticate a user. The processor may be configured to output at least one vibration signal to at least one touched object through the vibration module, receive at least one response signal for the vibration signal from the object through the vibration module, and perform biometric authentication for the object based on at least one of the vibration signal or the response signal. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a diagram illustrating an electronic device according to various embodiments. 
         FIG. 2  is a diagram illustrating a vibration module of  FIG. 1 . 
         FIGS. 3A, 3B and 3C  are diagrams for describing operational characteristics of the electronic device according to various embodiments. 
         FIG. 4  is a diagram illustrating an operating method of the electronic device according to various embodiments. 
         FIG. 5  is a diagram illustrating an operation of performing biometric authentication in the operating method of  FIG. 4 . 
         FIG. 6  is a diagram for describing an example of an operation of detecting biometric information in  FIG. 5 . 
         FIG. 7  is a diagram for describing another example of an operation of detecting biometric information in  FIG. 5 . 
         FIGS. 8A and 8B  are diagrams for describing a pre-processing operation of  FIG. 7 . 
         FIG. 9  is a diagram for describing still another example of an operation of detecting biometric information in  FIG. 5 . 
         FIG. 10  is a diagram illustrating an operating method of the electronic device according to various embodiments. 
     
    
    
     DETAILED DESCRIPTION 
     Hereinafter, various embodiments of this document are described with reference to the accompanying drawings. 
       FIG. 1  is a diagram illustrating an electronic device  100  according to various embodiments.  FIG. 2  is a diagram illustrating a vibration module  140  of  FIG. 1 .  FIGS. 3A, 3B and 3C  are diagrams for describing operational characteristics of the electronic device  100  according to various embodiments. 
     Referring to  FIG. 1 , the electronic device  100  according to various embodiments may include at least one of a communication module  110 , an input module  120 , an output module  130 , a vibration module  140 , a memory  150  or a processor  160 . In some embodiments, at least any one of the elements of the electronic device  100  may be omitted, or one or more other elements may be added to the electronic device  100 . 
     The communication module  110  of the electronic device  100  may perform communication with an external device  181 ,  183 . The communication module  110  may set up a communication channel between the electronic device  100  and the external device  181 ,  183 , and may perform communication with the external device  181 ,  183  through the communication channel. The communication module  110  may include at least one of a wired communication module or a wireless communication module. The wired communication module is connected to the external device  181  through wires, and may communicate with the external device  181  through the wires. The wireless communication module may include at least one of a short-distance communication module or a long-distance communication module. The short-distance communication module may communicate with the external device  181  using the short-distance communication method. For example, the short-distance communication method may include Bluetooth, WiFi direct, or infrared data association (IrDA). The long-distance communication module may communicate with the external device  183  using the short-distance communication method. In this case, the long-distance communication module may communicate the external device  183  over a network  190 . For example, the network  190  may include a cellular network, the Internet, or computer networks, such as a local area network (LAN) or a wide area network (WAN). 
     The input module  120  may input an instruction or data to be used in at least one of the elements of the electronic device  100 . The input module  120  may include at least one of an input device configured to enable a user to directly input an instruction or data to the electronic device  100  or a sensor device configured to generate a signal by detecting a surrounding environment and to input data converted from a signal. For example, the input device may include at least one of a microphone, a mouse or a keyboard. In some embodiments, the sensor device may include at least one of a touch circuitry configured to sense a touch or a sensor circuit configured to measure the intensity of a force generated by a touch. 
     The output module  130  may output information to the outside of the electronic device  100 . The output module  130  may include at least one of a display device capable of visually displaying information or an audio device capable of outputting information in an audio signal form. For example, the display device may include at least one of a display, a hologram device or a projector. In some embodiments, the display device may be assembled with at least any one of the touch circuitry of the input module  120  or the sensor circuit of the input module  120  configured to measure the intensity of a force generated by a touch, thus being implemented as a touch screen. For example, the audio device may include at least one of a speaker or a receiver. The speaker and the receiver may be divided and used depending on respective uses, and may be selectively used regardless of their uses. 
     The vibration module  140  may be configured to detect a vibration characteristic of the body of a user. In this case, the body of the user is unique, and each portion of the body, that is, an object, is also unique. Accordingly, a vibration characteristic of the object may also be unique. Accordingly, the object may be identified based on the vibration characteristic, and the user may also be identified. As illustrated in  FIG. 2 , the vibration module  140  may include at least one of at least one contact module  210 , at least one vibration generation module  220  or at least one response sensing module  230 . 
     The contact module  210  may be provided for a contact with an object. For example, the contact module  210  may include a contact plate for having a direct contact with an object and a contact sensor for detecting at least any one of a temperature change, an electrical change or a pressure change attributable to a contact with an object. 
     The vibration generation module  220  may generate a mechanical vibration for an object. For example, the vibration generation module  220  includes an excitation device. The excitation device may generate a vibration using at least any one of a piezo-electric method, a voice coil method or a rotor method. Specifically, the vibration generation module  220  may generate its own vibration based on an electrical signal. In this case, the electrical signal may be converted into a vibration signal by the vibration generation module  220 . Accordingly, the vibration generation module  220  generates a vibration to the contact module  210 . When an object comes into contact with the contact module  210 , a vibration may be indirectly generated to the object through the contact module  210 . At this time, the vibration signal is transmitted to the contact module  210 . When the object comes into contact with the contact module  210 , the vibration signal may be output to the object through the contact module  210 . For example, the vibration generation module  220  includes a shaker. The shaker may operate in a mechanical, electrical or electro-hydraulic manner. In this case, the vibration generation module  220  may generate a vibration signal based on a predetermined parameter. For example, the parameter may include at least one of the intensity (or force), frequency, displacement, speed, or acceleration of a vibration. 
     The response sensing module  230  may measure a mechanical vibration for an object. For example, the response sensing module  230  includes a vibration arrestor. The vibration arrestor may measure a vibration using at least any one of a piezo-electric method, a voice coil method, a micro-electro mechanical systems (MEMS) method, an electrostatic method or a resistive method. Specifically, when an object comes into contact with the contact module  210 , a vibration is generated from the object, and thus a vibration may also be generated in the contact module  210 . Accordingly, the response sensing module  230  may measure a vibration from the contact module  210 . Accordingly, the response sensing module  230  may detect a response signal for a vibration signal. 
     According to one embodiment, in the contact module  210 , an excitation location where a vibration is generated by the vibration generation module  220  and a vibration arrest location where a vibration is measured by the response sensing module  230  may be the same. That is, the vibration generation module  220  may generate a vibration in one region of the contact module  210 . In response thereto, the response sensing module  230  may measure a vibration for the corresponding region of the contact module  210 . In other words, the vibration generation module  220  may output a vibration signal to the corresponding region of the contact module  210 . The response sensing module  230  may detect a response signal in the corresponding region of the contact module  210 . 
     According to another embodiment, in the contact module  210 , an excitation location and a vibration arrest location may be different. That is, the vibration generation module  220  may generate a vibration in a first region of the contact module  210 . In response thereto, the response sensing module  230  may measure a vibration in a second region of the contact module  210 . In other words, the vibration generation module  220  may generate a vibration signal to the first region of the contact module  210 . The response sensing module  230  may detect a response signal in the second region of the contact module  210 . 
     According to various embodiments, a vibration signal may be converted into a response signal while passing through an object, that is, the inside of the object. In this case, the vibration signal may be converted into the response signal while passing through at least any one of skin, muscle, a bone, or a joint or a blood vessel of the object. Accordingly, the response signal may be unique for each object. For example, if an object is a finger, frequency characteristics of response signals may be different depending on fingers, that is, an index finger, a middle finger, a ring finger, and a little finger, as illustrated in  FIG. 3A . The reason for this is that a biometric characteristic is different depending on a finger, that is, an index finger, a middle finger, a ring finger, or a little finger. In this case, collected response signals of fingers, that is, an index finger, a middle finger, a ring finger, and a little finger, may be classified based on frequency characteristics as illustrated in  FIG. 3B . Such classification results may indicate high classification accuracy as in Table 1 below. 
     
       
         
           
               
             
               
                 TABLE 1 
               
             
            
               
                   
               
               
                 CLASSIFICATION RESULTS 
               
            
           
           
               
               
               
            
               
                   
                 FINGER 
                 CLASSIFICATION ACCURACY 
               
               
                   
                   
               
               
                   
                 INDEX FINGER 
                 97.9% 
               
               
                   
                 MIDDLE FINGER 
                 99.4% 
               
               
                   
                 RING FINGER 
                 98.9% 
               
               
                   
                 LITTLE FINGER 
                 97.2% 
               
               
                   
                   
               
            
           
         
       
     
     The memory  150  may store various data used by at least one of the elements of the electronic device  100 . For example, the memory  150  may include at least one of a volatile memory or a non-volatile memory. Data may include a program or input data or output data for an instruction related to the program. The program may be stored in the memory  150  as software, and may include at least one of an operating system, middleware or an application. The memory  150  may store user information. The user information may include identification information of the user, and a vibration characteristic for the ID of each object of the user and each object mapped to the ID, that is, biometric information. 
     The processor  160  may control at least one of the elements of the electronic device  100  by executing the program of the memory  150 , and may perform data processing or an operation. The processor  160  may execute an application. The processor  160  may perform the authentication of a user based on a vibration characteristic of the body of the user. At this time, the processor  160  may output a vibration signal through the vibration module  140 , and may receive a response signal for the vibration signal. For example, when the electronic device  100  wakes up from a sleep state, the processor  160  may drive the vibration module  140 . In this case, while the electronic device  100  is in the sleep state, when at least any one of a change in the posture of the electronic device  100 , the gripping of a user for the electronic device  100 , a contact of an object with the vibration module  140 , or the input of the user for activating the electronic device  100  is detected, the electronic device  100  may wake up. Meanwhile, the processor  160  may provide a graphic user interface (GUI) for the authentication of a user. For example, the processor  160  may guide a location of the vibration module  140 , particularly, the contact module  210  or an object for the authentication of a user, using various drawings or text through the GUI. Furthermore, the processor  160  may perform biometric authentication on the object based on at least one of a vibration signal or a response signal. Accordingly, the processor  160  may identify the object and also identify the user. In this case, the processor  160  may detect biometric information from at least any one of the vibration signal or the response signal, and may identify the object or the user based on the biometric information. 
     According to a first embodiment, the processor  160  may detect biometric information from a response signal. For example, the processor  160  may detect time-series data for a response signal in a time region, and may detect biometric information based on the time-series data. In this case, the processor  160  may detect the biometric information based on at least one of a pattern or shape of the time-series data. For another example, the processor  160  may detect, as biometric information, at least any one of a displacement, speed or acceleration for vibration pressure in a time region based on a response signal. For still another example, the processor  160  may detect, as biometric information, at least any one of a displacement, speed or acceleration for vibration pressure in a frequency region based on a response signal. For still another example, the processor  160  may detect at least one peak point from a response signal, and may detect information on the peak point as biometric information. 
     According to a second embodiment, the processor  160  may detect biometric information by combining a plurality of response signals. For example, the processor  160  may combine objects as a password having a given pattern, for example, an index finger-middle finger-ring finger or an index finger-middle finger-index finger-ring finger. For another example, the processor  160  may detect biometric information by calculating a ratio of response signals, for example, a ratio of response signals to at least two fingers. For still another example, when viewed in a long term, the accuracy of biometric information detected from a ratio of response signals may be higher than the accuracy of biometric information detected from one response signal as in Table 2 below. In this case, the accuracy of the biometric information detected from the ratio of the response signals can be maintained over time as illustrated in  FIG. 3C . 
     
       
         
           
               
               
               
               
             
               
                   
                 TABLE 2 
               
               
                   
                   
               
               
                   
                 On the day 
                 1 day later 
                 2 days later 
               
               
                   
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
            
               
                 Digit2 
                 97.3 
                 37.5 
                 63.0 
               
               
                 Digit3 
                 99.1 
                 67.3 
                 62.8 
               
               
                 Digit (2, 3) ratio 
                 99.5 
                 74.8 
                 93.3 
               
               
                   
               
            
           
         
       
     
     To this end, the processor  160  may simultaneously output a plurality of vibration signals, may receive response signals for the vibration signals, respectively, and may detect biometric information from the response signals. To this end, the vibration module  140  may include a plurality of the contact modules  210 , a plurality of the vibration generation modules  220 , and a plurality of the response sensing modules  230 . When a plurality of objects comes into contact with the contact modules  210 , respectively, the processor  160  may receive response signals and detect biometric information from the response signals. Alternatively, the processor  160  may sequentially output a plurality of vibration signals, may receive response signals for the vibration signals, respectively, and may detect biometric information from the response signals. To this end, as a plurality of objects sequentially comes into contact with the contact modules  210 , the processor  160  may sequentially receive the response signals and detect biometric information from the response signals. Accordingly, the processor  160  may identify the objects based on the biometric information, and may identify a user by combining the objects. 
     According to a third embodiment, the processor  160  may calculate a frequency response function (FRF) based on a vibration signal and a response signal, and may detect biometric information based on the FRF. In this case, the processor  160  may determine at least any one of a displacement, speed or acceleration for vibration pressure in the frequency region of the vibration signal as first response information, may detect at least any one of a displacement, speed or acceleration for vibration pressure in the frequency region as second response information based on the response signal, and may calculate the FRF using the first response information and the second response information. In this case, the processor  160  may detect the FRF as biometric information. Alternatively, the processor  160  may pre-process the FRF, and may detect biometric information based on the pre-processed FRF. In this case, the biometric information may include a mass parameter, hardness parameter, and attenuation parameter of the FRF. 
     For example, the processor  160  may perform pre-processing in order to remove an effect attributable to a vibration component of the electronic device  100  or the vibration module  140  from an FRF. In this case, the vibration signal and the response signal may include a vibration component of the electronic device  100  or the vibration module  140  itself, in addition to a vibration component of an object. Accordingly, the processor  160  can remove an effect attributable to a vibration component of the electronic device  100  or the vibration module  140  from the FRF. For example, the vibration component of the electronic device  100  or the vibration module  140  may be related to weight of the electronic device  100  or the vibration module  140 . 
     For another example, the processor  160  may perform pre-processing to generate a frequency spectrum for an FRF. In this case, the processor  160  may detect a pattern, a shape, etc. of the frequency spectrum. Furthermore, the processor  160  may compare the FRF with a modeled FRF based on the frequency spectrum. In this case, the memory  150  may store a modeled FRF for an object or a user. That is, the processor  160  may learn an FRF based on a pattern, a shape, etc. of a frequency spectrum, and may check a difference between the FRF and the modeled FRF. In this case, the processor  160  may selectively use some of the frequency spectrum. Specifically, different pieces of importance may be assigned to frequency bands. The processor  160  may extract at least some of the frequency spectrum in accordance with at least one frequency band having predetermined importance or more, and may use the extracted portion. 
     The electronic device  100  according to various embodiments of this document may be various types of devices. The electronic device  100  may include a portable communication device (e.g., a smart phone), a computer device, a portable multimedia device, a portable medical device, a camera, a wearable device, or home appliances, for example. The electronic device  100  according to various embodiments of this document is not limited to the aforementioned devices. 
     The electronic device  100  according to various embodiments may include the vibration module  140 , and the processor  160  coupled to the vibration module  140  and configured for the authentication of a user. 
     According to various embodiments, the processor  160  may be configured to output at least one vibration signal to at least one touched object through the vibration module  140 , receive at least one response signal for the vibration signal from the object through the vibration module  140 , and to perform biometric authentication on the object based on at least one of the vibration signal or the response signal. 
     According to various embodiments, the vibration module  140  may include the contact module  210  configured to come into contact with an object, the vibration generation module  220  configured to generate a vibration in the contact module  210  and to output a vibration signal in response to the generated vibration, and the response sensing module  230  configured to measure the vibration generated in the contact module  210  and to detect a response signal in response to the measured vibration. 
     According to one embodiment, the vibration generation module  220  may generate a vibration in one region of the contact module  210 . The response sensing module  230  may measure a vibration in one region of the contact module  210 . 
     According to another embodiment, the vibration generation module  220  may generate a vibration in one region of the contact module  210 . The response sensing module  230  may measure a vibration in another region of the contact module  210 . 
     According to various embodiments, the processor  160  may be configured to calculate an FRF based on a vibration signal and a response signal and to perform biometric authentication on an object based on the FRF. 
     According to various embodiments, the processor  160  may be configured to determine at least any one of a displacement, speed or acceleration for vibration pressure in the frequency region of a vibration signal as first response information, detect at least any one of the displacement, speed or acceleration for vibration pressure in the frequency region as second response information based on a response signal, and calculate an FRF based on the first response information and the second response information. 
     According to various embodiments, the processor  160  may be configured to pre-process an FRF in order to remove an effect attributable to a vibration component of the electronic device  100  or the vibration module  140  from the RFT and to perform biometric authentication on an object based on the pre-processed FRF. 
     According to various embodiments, an effect attributable to a vibration component of the electronic device  100  or the vibration module  140  may be related to weight of the electronic device  100  or the vibration module  140 . 
     According to various embodiments, the processor  160  may be configured to generate a frequency spectrum for an FRF and to perform biometric authentication on an object by comparing the FRF with a modeled FRF based on the frequency spectrum. 
     According to various embodiments, the processor  160  may be configured to detect biometric information based on an FRF and to determine whether biometric authentication is successful based on whether user information corresponding to the biometric information is detected. 
     According to various embodiments, biometric information may include a mass parameter, hardness parameter and attenuation parameter of an FRF. 
     According to various embodiments, the processor  160  may be configured to detect time-series data of a response signal in a time region and to perform biometric authentication on an object based on at least one of a pattern or shape of the time-series data. 
     According to various embodiments, the processor  160  may be configured to combine a plurality of response signals according to the sequence of time and to perform biometric authentication on a combination of a plurality of objects according to the sequence of time. 
       FIG. 4  is a diagram illustrating an operating method of the electronic device  100  according to various embodiments. 
     Referring to  FIG. 4 , at operation  410 , the electronic device  100  may output at least one vibration signal to at least one touched object. The processor  160  may output the vibration signal through the vibration module  140 . At this time, the vibration generation module  220  may generate the vibration signal based on a predetermined parameter. For example, the parameter may include at least one of the intensity (or force), frequency, displacement, speed, or acceleration of the vibration signal. In this case, when a contact of the object with the vibration module  140  is detected, the processor  160  may output the vibration signal. Specifically, the vibration generation module  220  may generate its own vibration based on an electrical signal. In this case, in the vibration generation module  220 , the electrical signal may be converted into the vibration signal. Accordingly, the vibration generation module  220  generates the vibration to the contact module  210 . When the object comes into contact with the contact module  210 , a vibration may also be indirectly generated to the object through the contact module  210 . At this time, the vibration signal is transmitted to the contact module  210 . When the object comes into contact with the contact module  210 , the vibration signal may be output to the object through the contact module  210 . According to various embodiments, the vibration signal may be converted into a response signal while passing through the object, that is, the inside of the object. In this case, the vibration signal may be converted into the response signal while passing through at least any one of skin, muscle, a bone, a joint or a blood vessel of the object. 
     At operation  420 , the electronic device  100  may receive at least one response signal for the vibration signal from the object. The processor  160  may receive the response signal through the vibration module  140 . In this case, the processor  160  may detect, as the response signal, a signal received within a predetermined time range after outputting the vibration signal. Specifically, when the object comes into contact with the contact module  210 , a vibration is generated from the object, and thus a vibration may also be generated from the contact module  210 . Accordingly, the response sensing module  230  may measure the vibration from the contact module  210 . Accordingly, the response sensing module  230  may detect the response signal for the vibration signal. 
     At operation  430 , the electronic device  100  may perform biometric authentication on the object. The processor  160  may perform the biometric authentication the an object based on at least one of the vibration signal or the response signal. Accordingly, the processor  160  may identify the object and also identify a user. Furthermore, the processor  160  may control an operation of at least any one of the electronic device  100  or the external device  181 ,  183  based on whether the biometric authentication is successful. 
       FIG. 5  is a diagram illustrating an operation of performing biometric authentication in the operating method of  FIG. 4 .  FIG. 6  is a diagram for describing an example of an operation of detecting biometric information in  FIG. 5 . 
     Referring to  FIG. 5 , at operation  510 , the electronic device  100  may detect biometric information on an object. The processor  160  may detect biometric information from at least one of a vibration signal or a response signal. 
     According to a first embodiment, the processor  160  may detect biometric information from a response signal. For example, the processor  160  may detect time-series data of the response signal in a time region, and may detect biometric information based on the time-series data. In this case, the processor  160  may detect the biometric information based on at least one of a pattern or shape of the time-series data. For another example, the processor  160  may detect at least any one of a displacement, speed or acceleration for vibration pressure in the time region as the biometric information based on the response signal. For still another example, the processor  160  may detect at least any one of a displacement, speed or acceleration for vibration pressure in a frequency region as biometric information based on the response signal. For still another example, as illustrated in  FIG. 6 , the processor  160  may detect at least one peak point from the response signal, and may detect information on the peak point as the biometric information. 
     According to a second embodiment, the processor  160  may detect biometric information by combining a plurality of response signals. For example, the processor  160  may combine objects as a password having a given pattern, for example, like an index finger-middle finger-ring finger or an index finger-middle finger-index finger-ring finger. For another example, the processor  160  may detect the biometric information by calculating a ratio of response signals, for example, a ratio of response signals for at least two fingers. 
     To this end, the processor  160  may simultaneously output a plurality of vibration signals, may receive response signals for the respective vibration signals, and may detect biometric information from the response signals. To this end, the vibration module  140  may include a plurality of the contact modules  210 , a plurality of the vibration generation modules  220 , and a plurality of the response sensing modules  230 . When a plurality of objects comes into contact with the contact modules  210 , respectively, the processor  160  may receive response signals and detect biometric information from the response signals. Alternatively, the processor  160  may sequentially output a plurality of vibration signals, may receive response signals for the vibration signals, respectively, and may detect biometric information from the response signals. To this end, when the plurality of objects sequentially comes into contact with the contact modules  210 , the processor  160  may sequentially receive the response signals and detect the biometric information from the response signals. 
     According to a third embodiment, the processor  160  may calculate an FRF based on a vibration signal and a response signal. Furthermore, the processor  160  may detect biometric information based on the FRF. This will be more specifically described with reference to  FIGS. 7, 8A, 8B and 9 . 
       FIG. 7  is a diagram for describing another example of an operation of detecting biometric information in  FIG. 5 .  FIGS. 8A and 8B  are diagrams for describing a pre-processing operation of  FIG. 7 . 
     Referring to  FIG. 7 , at operation  710 , the electronic device  100  may calculate an FRR based on a vibration signal and a response signal. In this case, the processor  160  may calculate the FRF using first response information related to the vibration signal and second response information related to the response signal. In this case, as in Equation 1 below, the processor  160  may calculate the FRF as a ratio of the first response information and the second response information. For example, the processor  160  may determine, as the first response information, at least any one of a displacement, speed or acceleration for vibration pressure in the frequency region of the vibration signal, and may detect, as the second response information, at least any one of the displacement, speed or acceleration for vibration pressure in the frequency region based on the response signal. 
     
       
         
           
             
               
                 
                   
                     
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     In Equation 1, H(w) may indicate the FRF, F(w) may indicate the first response information, A(w) may indicate the second response information, and w may indicate an angular frequency of the vibration signal. Furthermore, M may indicate a mass parameter of the electronic device  100  or the vibration module  140 , K may indicate a hardness parameter of the electronic device  100  or the vibration module  140 , and C may indicate an attenuation parameter of the electronic device  100  or the vibration module  140 . 
     At operation  720 , the electronic device  100  may perform pre-processing on the FRF. The processor  160  may perform the pre-processing in order to remove an effect attributable to a vibration component of the electronic device  100  or the vibration module  140  from the FRF. In this case, the vibration signal and the response signal may include a vibration component of the electronic device  100  or the vibration module  140  itself, in addition to a vibration component of an object. Accordingly, the processor  160  may remove, from the FRF, the effect attributable to the vibration component of the electronic device  100  or the vibration module  140 . For example, the vibration component of the electronic device  100  or the vibration module  140  may be related to weight of the electronic device  100  or the vibration module  140 . The processor  160  may remove, from the FRF, a component related to weight of the electronic device  100  or the vibration module  140  as in Equation 2. For example, as illustrated in  FIG. 8A , the processor  160  may remove, from the FRF, a component related to weight of the electronic device  100  or the vibration module  140 . Accordingly, as illustrated in  FIG. 8B , the processor  160  may obtain a pre-processed FRF. 
     
       
         
           
             
               
                 
                   
                     H 
                     true 
                   
                   = 
                   
                     
                       
                         H 
                         m 
                       
                        
                       
                         ( 
                         ω 
                         ) 
                       
                     
                     
                       
                         
                           H 
                           Dev 
                         
                          
                         
                           ( 
                           ω 
                           ) 
                         
                       
                       - 
                       
                         
                           m 
                           Dev 
                         
                          
                         
                           
                             H 
                             m 
                           
                            
                           
                             ( 
                             ω 
                             ) 
                           
                         
                       
                     
                   
                 
               
               
                 
                   ( 
                   2 
                   ) 
                 
               
             
           
         
       
     
     In Equation 2, H m  may indicate an FRF calculated in the electronic device  100 , H Dev  may indicate an FRF when an object is not present, H true  may indicate an FRF obtained by removing, from H m , a component related to weight of the electronic device  100  or the vibration module  140 , and m Dev  may indicate the mass of the electronic device  100  or the vibration module  140 . 
     At operation  730 , the electronic device  100  may detect the FRF as biometric information. The processor  160  may detect, as the biometric information, any one of the FTF calculated FRF at operation  710  or the FRF pre-processed at operation  720 . Thereafter, the electronic device  100  may return to  FIG. 5 . 
       FIG. 9  is a diagram for describing still another example of the operation of detecting biometric information in  FIG. 5 . 
     Referring to  FIG. 9 , at operation  910 , the electronic device  100  may calculate an FRF based on a vibration signal and a response signal. In this case, the processor  160  may calculate the FRF using first response information related to the vibration signal and second response information related to the response signal. In this case, the processor  160  may calculate the FRF using a method similar to operation  710  of  FIG. 7 . 
     At operation  920 , the electronic device  100  may perform pre-processing on the FRF. The processor  160  may perform the pre-processing in order to remove, from the FRF, an effect attributable to a vibration component of the electronic device  100  or the vibration module  140 . In this case, the processor  160  may remove, from the FRF, the effect attributable to the vibration component of the electronic device  100  or the vibration module  140  using a method similar to operation  720  of  FIG. 7 . Furthermore, the processor  160  may perform the pre-processing in order to generate a frequency spectrum for the FRF. In this case, the processor  160  may detect a pattern, a shape, etc. of the frequency spectrum. 
     At operation  930 , the electronic device  100  may compare the FRF with a modeled FRF. In this case, the processor  160  may compare the FRF with the modeled FRF based on a frequency spectrum. To this end, the memory  150  may store the modeled FRF. The modeled FRF is generated through biomechanical modeling for an object or a user, and may be generated when the FRF for a user is previously registered. That is, the processor  160  may learn an FRF based on a pattern, a shape, etc. of a frequency spectrum, and may check a difference between the FRF and a modeled FRF. In this case, the processor  160  may selectively use some of the frequency spectrum. Specifically, different pieces of importance may be assigned to frequency bands. The processor  160  may extract at least some of the frequency spectrum in accordance with at least one frequency band having predetermined importance or more, and may use the extracted portion. In this case, for optimization, the processor  160  may use a root-mean-square deviation of the FRF and the modeled FRF as a target function. Specifically, the processor  160  may use, as the target function, at least any one of a root-mean-square deviation within a measurement frequency range or a root-mean-square deviation obtained by applying a weight near the resonant frequency of the FRF. 
     At operation  940 , the electronic device  100  may detect biometric information from the FRF based on the modeled FRF. The processor  160  may detect a mass parameter, hardness parameter, and attenuation parameter of the FRF as the biometric information based on the modeled FRF. In this case, the mass parameter, the hardness parameter, and the attenuation parameter may be related to the FRF as in Equation 1. Thereafter, the electronic device  100  may return to  FIG. 5 . 
     Referring back to  FIG. 5 , at operation  520 , the electronic device  100  may classify the biometric information. The processor  160  may search for previously stored user information based on the biometric information. In this case, the processor  160  may search for the user information based on similarity between the user information and the biometric information. To this end, the processor  160  may use classification machine learning. For example, the processor  160  may classify the biometric information using a binary classification support vector machine (SVM). At operation  530 , the electronic device  100  may determine whether user information identical with the biometric information is detected. The processor  160  may detect, as the user information identical with the biometric information, user information whose similarity with the biometric information is greater than a threshold value. 
     When the identical user information is detected at operation  530 , at operation  540 , the electronic device  100  may process that the biometric authentication on the object is successful. The processor  160  may identify a user based on the user information. Furthermore, the processor  160  may control an operation of at least any one of the electronic device  100  or the external device  181 ,  183  based on access rights assigned to the user. For example, if the electronic device  100  is a smart phone, the electronic device  100  may release the lock of the smart phone, and may permit access by a user. For another example, if the external device  181 ,  183  is a door, the electronic device  100  may open the door. For still another example, if the external device  181 ,  183  is an elevator, the electronic device  100  may permit an operation of the elevator. 
     If identical user information is not detected at operation  530 , at operation  550 , the electronic device  100  may process that the biometric authentication on the object has failed. The processor  160  may control an operation of at least any one of the electronic device  100  or the external device  181 ,  183  in order to limit access by the user. For example, if the electronic device  100  is a smart phone, the electronic device  100  may maintain the lock of the smart phone. For another example, if the external device  181 ,  183  is a door, the electronic device  100  may close the door or maintain the closing of the door. For still another example, if the external device  181 ,  183  is an elevator, the electronic device  100  may stop an operation of the elevator. 
     According to various embodiments, the electronic device  100  may register user information. Accordingly, the electronic device  100  may perform the authentication of a user based on the user information. This will be more specifically described with reference to  FIG. 10 . 
       FIG. 10  is a diagram illustrating an operating method of the electronic device  100  according to various embodiments. 
     Referring to  FIG. 10 , at operation  1010 , the electronic device  100  may output at least one vibration signal to at least one touched object. The processor  160  may output the vibration signal through the vibration module  140 . Specifically, the vibration generation module  220  may generate its own vibration based on an electrical signal. In this case, in the vibration generation module  220 , the electrical signal may be converted into the vibration signal. Accordingly, the vibration generation module  220  generates the vibration to the contact module  210 . When an object comes into contact with the contact module  210 , a vibration may also be indirectly generated to the object through the contact module  210 . At this time, the vibration signal is transmitted to the contact module  210 . When the object comes into contact with the contact module  210 , the vibration signal may be output to the object through the contact module  210 . In this case, the vibration generation module  220  may generate the vibration based on a predetermined parameter. For example, the parameter may include at least one of the intensity (or force), frequency, displacement, speed, or acceleration of the vibration. According to various embodiments, the vibration signal may be converted into the response signal while passing through the object, that is, the inside of the object. In this case, the vibration signal may be converted into the response signal while passing through at least any one of skin, muscle, a bone, a joint or a blood vessel of the object. 
     At operation  1020 , the electronic device  100  may receive at least one response signal for the vibration signal from the object. The processor  160  may receive the response signal through the vibration module  140 . In this case, the processor  160  may detect, as the response signal, a signal received within a predetermined time range after outputting the vibration signal. Specifically, when the object comes into contact with the contact module  210 , a vibration may also be generated from the contact module  210  because a vibration is generated from the object. Accordingly, the response sensing module  230  may measure the vibration from the contact module  210 . Accordingly, the response sensing module  230  may detect the response signal for the vibration signal. 
     At operation  1030 , the electronic device  100  may register user information. The processor  160  may register the user information based on at least one of the vibration signal or the response signal. The processor  160  may detect biometric information of the user based on at least one of the vibration signal or the response signal, and may store the biometric information in the memory  150  as the user information along with identification information of the user. In this case, the operation of detecting biometric information based on at least one of a vibration signal or a response signal is similar to that described above, and thus a detailed description thereof is omitted. 
     An operating method of the electronic device  100  according to various embodiments may include outputting at least one vibration signal to at least one touched object through the vibration module  140 , receiving at least one response signal for the vibration signal from the object through the vibration module  140 , and performing biometric authentication on the object based on at least one of the vibration signal or the response signal. 
     According to various embodiments, the vibration module  140  may include the contact module  210  configured to come into contact with an object, the vibration generation module  220  configured to generate a vibration in the contact module  210  and to output a vibration signal in response to the generated vibration, and the response sensing module  230  configured to measure the vibration generated in the contact module  210  and to detect a response signal in response to the measured vibration. 
     According to one embodiment, the vibration generation module  220  may generate a vibration in one region of the contact module  210 . The response sensing module  230  may measure a vibration in one region of the contact module  210 . 
     According to another embodiment, the vibration generation module  220  may generate a vibration in one region of the contact module  210 . The response sensing module  230  may measure a vibration in another region of the contact module  210 . 
     According to various embodiments, the performing of biometric authentication may include calculating an FRF based on the vibration signal and the response signal, and performing the biometric authentication on the object based on the FRF. 
     According to various embodiments, the calculating of an FRF may include determining, as first response information, at least any one of a displacement, speed or acceleration for vibration pressure in the frequency region of the vibration signal based on the response signal, detecting, as second response information, at least any one of the displacement, speed or acceleration for vibration pressure in the frequency region, and calculating the FRF using the first response information and the second response information. 
     According to various embodiments, the performing of the biometric authentication based on the FRF may include pre-processing the FRF in order to remove, from the FRF, an effect attributable to a vibration component of the electronic device  100  or the vibration module  140 , and performing the biometric authentication on the object based on the pre-processed FRF. 
     According to various embodiments, the effect attributable to the vibration component of the electronic device  100  or the vibration module  140  may be related to weight of the electronic device  100  or the vibration module  140 . 
     According to various embodiments, the performing of the biometric authentication based on the FRF may include generating a frequency spectrum for the FRF, and performing the biometric authentication on the object by comparing the FRF with a modeled FRF based on the frequency spectrum. 
     According to various embodiments, the performing of the biometric authentication based on the FRF may include detecting biometric information based on the FRF, and determining whether the biometric authentication is successful based on whether user information corresponding to the biometric information is detected. 
     According to various embodiments, the biometric information may include a mass parameter, hardness parameter, and attenuation parameter of the FRF. 
     According to various embodiments, the performing of the biometric authentication may include detecting time-series data of the response signal in a time region, and performing the biometric authentication on the object based on at least one of a pattern or shape of the time-series data. 
     According to various embodiments, the performing of the biometric authentication may include combining a plurality of response signals according to the sequence of time and performing the biometric authentication on a combination of a plurality of objects according to the sequence of time. 
     According to various embodiments, the electronic device  100  can perform biometric authentication on a user based on a vibration characteristic of the body. Accordingly, the electronic device  100  can perform biometric authentication on a user even if the user does not accurately bring a predetermined portion of his or her body into contact with the electronic device  100 . Accordingly, the electronic device  100  can perform biometric authentication on a user even without degrading user convenience. Furthermore, the size of the electronic device  100  can be reduced and a degree of freedom of the design of the electronic device  100  can be secured because a component for detecting a vibration characteristic of the body, that is, the vibration module  140 , does not need to be exposed to a surface of the electronic device  100 . Accordingly, the electronic device  100  can efficiently perform biometric authentication on a user. 
     Various embodiments of this document and the terms used in the embodiments are not intended to limit the technology described in this document to a specific embodiment, but should be construed as including various changes, equivalents and/or alternatives of a corresponding embodiment. Regarding the description of the drawings, similar reference numerals may be used in similar elements. An expression of the singular number may include an expression of the plural number unless clearly defined otherwise in the context. In this document, an expression, such as “A or B”, “at least one of A or/and B”, “A, B or C” or “at least one of A, B and/or C”, may include all of possible combinations of listed items together. Expressions, such as “a first,” “a second,” “the first” and “the second”, may modify corresponding elements regardless of the sequence and/or importance, and are used to only distinguish one element from the other element and do not limit corresponding elements. When it is described that one (e.g., first) element is “(operatively or communicatively) connected to” or “coupled with” the other (e.g., second) element, one element may be directly connected to the other element or may be connected to the other element through another element (e.g., third element). 
     The “module” used in this document includes a unit configured as hardware, software or firmware, and may be interchangeably used with a term, such as logic, a logical block, a part or a circuit. The module may be an integrated part, a minimum unit to perform one or more functions, or a part thereof. For example, the module may be configured as an application-specific integrated circuit (ASIC). 
     Various embodiments of this document may be implemented as software including one or more instructions stored in a storage medium (e.g., the memory  150 ) readable by a machine (e.g., the electronic device  100 ). For example, a processor (e.g., the processor  160 ) of the machine may invoke at least one of one or more stored commands from the storage medium, and may execute the command. This enables the machine to execute at least one function based on the fetched at least one command. The one or more instructions may include code generated by a compiler or code executable by an interpreter. The storage medium readable by the machine may be provided in the form of a non-transitory storage medium. In this case, the term “non-transitory” means that the storage medium is a tangible device and does not include a signal (e.g., electromagnetic waves). The term does not distinguish between a case where data is semi-permanently stored in the storage medium and a case where data is temporally stored in the storage medium. 
     According to various embodiments, each of elements (e.g., module or program) may include a single entity or a plurality of entities. According to various embodiments, one or more of the aforementioned elements or operations may be omitted or one or more other elements or operations may be added. Alternatively or additionally, a plurality of elements (e.g., modules or programs) may be integrated into a single element. In such a case, the integrated element may perform one or more functions of each of the plurality of elements identically or similarly to a function performed by a corresponding element of the plurality of elements before they are integrated. According to various embodiments, operations performed by a module, a program or other elements may be executed sequentially, in parallel, repeatedly, or heuristically, or one or more of the operations may be executed in different order or may be omitted, or one or more operations may be added. 
     According to various embodiments, the electronic device can perform biometric authentication on a user based on a vibration characteristic of the body. Accordingly, the electronic device can perform biometric authentication on a user even if the user does not accurately bring a predetermined portion of his or her body into contact with the electronic device. Accordingly, the electronic device can perform biometric authentication on a user even without degrading user convenience. Furthermore, the size of the electronic device can be reduced and a degree of freedom of the design of the electronic device can be secured because a component for detecting a vibration characteristic of the body does not need to be exposed to a surface of the electronic device. Accordingly, the electronic device can efficiently perform biometric authentication on a user.