KR20230132899A - Ultrasonic Sound Guide System and Method for the Visually Impaired - Google Patents

Abstract

The present invention discloses an ultrasonic sound guidance system and method that informs the destination location at the final stage to enable visually impaired people to walk safely. The ultrasonic sound guidance system includes a transmitter 100 that modulates the recorded audible sound into an ultrasonic signal and broadcasts the ultrasonic sound, a receiver 200 that receives the ultrasonic broadcast and converts it to an audible frequency to generate the recorded audible sound, and one or two It includes a single-channel or dual-channel receiving device configured to include two receivers. In the ultrasonic sound guidance method, the user 300 uses a single or dual channel receiver to recognize content transmitted from the speaker 202 and proceeds in a desired direction. Users of dual-channel receivers estimate the direction of the transmitter using the human ear-based sound source direction measurement ability, while users of single-channel receivers estimate the direction of the transmitter by recognizing the sound level that varies depending on the direction of the receiver. The user safely arrives at the final destination where the transmitter is located by continuously changing direction and moving forward. According to the present invention, by using ultrasonic sound, which is an inaudible frequency, it is possible to selectively provide acoustic information only to visually impaired people holding a receiver and enable them to recognize the destination and guide direction in a safe and non-contact manner.

Description

Ultrasonic sound guide system and method for the visually impaired {Ultrasonic Sound Guide System and Method for the Visually Impaired}

The present invention relates to an acoustic guidance system for the visually impaired. More specifically, a transmitter is installed at various destinations and the visually impaired can use a receiver to find a desired location through acoustic guidance and sound characteristics in the inaudible ultrasonic band. It's about a system that guides you.

Visually impaired people (blind or people whose vision cannot be corrected to near normal levels, also referred to as users in the present invention) experience various difficulties in recognizing general surroundings and walking. Existing methods such as guide dogs, canes, tactile Braille, and audio alarms improve the safety and efficiency of walking. Recently, smart devices based on GPS (Global Positioning System), cameras, and sensors convey the surrounding situation to visually impaired people using touch or sound. However, from the perspective of the visually impaired, walking is still difficult in the final stage due to the ambiguity of the location of the destination. Due to a lack of visual information, visually impaired people cannot specify an accurate final location near the destination without prior experience. Indoor walking further exacerbates destination ambiguity due to structural similarities between locations. Smart devices can use cameras and sensors to pinpoint their exact location, but there are still problems communicating that information to the user. Smart devices are not widely used due to implementation complexity along with generally inconsistent performance.

A simple solution to the near-destination, last-mile walking problem is to have someone say the name of the location at the destination. Humans' ability to measure the direction of a sound source instinctively finds the destination. Direction and distance to the destination are inferred by differences in arrival signals between ears based on magnitude, time, and frequency. A pre-recorded message from a speaker could provide a solution for last-mile walking. Sound-based assistive devices are implemented and used on streets and sidewalks, especially at intersections. The location of the signal and the direction of the crosswalk are guided by designated voice signals. Sound devices can be used to support outdoor activities, such as sports activities for the visually impaired, identification of points of interest, and safe walking. Maintaining the sustainability of assistive devices based on acoustic signals requires a balance between accessibility and the environment. Due to the audible sound broadcast, sound-based devices have limitations in typical installations.

With an appropriate transmitter, inaudible acoustic propagation overcomes installation problems caused by noise pollution because information is transmitted to selected persons who own the receiver. Ultrasound is a frequency band signal beyond the audible range and exhibits acoustic properties such as directivity, attenuation, and overlap. Therefore, the acoustic signal transmitted by ultrasonic waves also delivers the same sound source direction measurement information to the receiver user based on signal strength and delay characteristics. To improve usability, the receiver can be implemented as a wearable or stand-alone device, including glasses, a neckband, a wand attachment, or a handheld device. Additionally, the receiving device must not interfere with the flow of external sound toward the external auditory canal in order to maintain the visually impaired person's ability to localize ambient sounds. The dual-channel receiver configuration can further improve final-step walking performance by explicitly using the human binaural-based sound source direction measurement ability. The present invention consists of a transmitter that broadcasts an acoustic signal through ultrasonic waves and a receiver that recovers the acoustic signal from the ultrasonic waves. The receiving device is a device that is formed based on a receiver and is worn or carried by the user to receive acoustic guidance. The receiver can also be implemented with smartphone application software based on the cell phone's microphone and speaker.

KR 10-1463986 B1 KR 10-1074431 B1 KR 10-1494054 B1 KR 10-2081193 B1 KR 10-1845754 B1

Pulkki, V., McCormack, L. & Gonzalez, R. Superhuman spatial hearing technology for ultrasonic frequencies. Sci Rep 11, 11608 (2021). https://doi.org/10.1038/s41598-021-90829-9 The summary of Non-Patent Document 1 states that there is no system that allows humans to determine the location of the sound source of ultrasonic sound. The method presented in the above paper estimates the precise direction of the sound source through multiple ultrasonic microphones, generates audible sound by applying mathematical spatial acoustic modeling based on this information, and then allows humans to estimate the location of the sound source. On the other hand, the present invention converts the ultrasonic sound into the audible band and then actively uses the physical characteristics of the ultrasonic sound and the ability to measure the direction of the sound source based on both ears of the human being to simply present a function to determine the location of the sound source of the ultrasonic sound.

The present invention provides a system and method for informing a visually impaired person of a destination location at the final stage in order to safely walk. Currently, visually impaired people use canes and Braille blocks on the sidewalk to walk, and at crosswalks, they can cross the sidewalk with the help of sound signals. However, although the safety and destination information needed by the visually impaired is partially implemented through Braille blocks or Braille information boards, there are many difficulties in recognition because it requires direct contact. This is because narrow Braille blocks and Braille information boards cannot cover the entire movement path of the visually impaired. Especially if it is your first time walking, independent walking is impossible as you need help from people around you.

Currently, as cutting-edge equipment is being developed, a variety of assistive devices for the visually impaired are being proposed. Assistive devices for this purpose are technically divided into two parts: peripheral awareness and information transmission. Peripheral awareness can be implemented using cameras and various sensors, but conveying information requires many challenges because it must be conveyed using hearing or touch of the visually impaired. Much research must be done to accurately convey three-dimensional surroundings to the visually impaired. An easy approach is to place a speaker at the guidance location or destination and transmit information through sound, which solves both surrounding awareness and information delivery. Perceiving information through sound leads to peripheral awareness, and the human's ability to measure the direction of sound sources based on both ears becomes a means of transmitting information. However, because everyone hears sound, its use should be limited due to noise pollution.

The problem to be solved by the present invention is to solve the problem of visually impaired people efficiently recognizing destination and safe location information. We want to safely recognize not only the information content but also the location of places that require attention, such as specific locations such as restrooms, conference rooms, elevators, stairs, and construction sites, for visually impaired people both indoors and outdoors. If acoustic speakers are placed at specific locations and sound is played, visually impaired people can recognize the sound safely, but since acoustic information is not required for everyone, it must be used selectively. The method presented in the present invention uses inaudible frequency sound, that is, ultrasonic sound, to selectively provide sound information only to visually impaired people who possess a receiver. Because ultrasonic sound also has acoustic characteristics, visually impaired people can use binaural-based sound source direction measurement capabilities to determine the location of the sound source. Additionally, the location of the sound source can be determined by changing the direction of the receiver. However, since the present invention does not have an active detection function for surrounding obstacles, it is essential for visually impaired people to use a cane.

An ultrasonic sound guidance system according to an embodiment of the above object includes a transmitter that modulates recorded audible sounds into ultrasonic signals and broadcasts ultrasonic waves; a receiver that receives the ultrasonic broadcast, converts it to an audible frequency, and generates the recorded audible sound; and a single-channel or dual-channel receiving device configured to include one or two of the receivers, wherein the transmitter includes a digital memory that stores the recorded digital sound signal. A transmission signal processing device that receives the recorded digital sound signal and converts it into an ultrasonic analog sound signal; and a transmission and propagation device that broadcasts the ultrasonic analog sound signal into the air, and the receiver includes a microphone that receives the ultrasonic broadcast transmitted from the transmitter and generates an ultrasonic signal. an analog amplifier that amplifies the received ultrasonic signal and generates an amplified ultrasonic signal; a receiving signal processing device that modifies the amplified ultrasonic signal to restore an analog sound signal transmitted from the transmitter; and a reception and propagation device that propagates the analog sound signal into the air.

In addition, the transmission signal processing device includes a digital low-frequency filter that generates a band-limited digital sound signal by allowing only the low-frequency band of the recorded digital sound signal to pass; Digital frequency shift for generating an ultrasonic digital sound signal by shifting the frequency band of the band-limited digital sound signal; And it may include a digital-to-analog converter that converts the ultrasonic digital sound signal into an ultrasonic analog sound signal.

In addition, the transmission signal processing device includes a digital-to-analog converter that converts the recorded digital sound signal into an analog sound signal; an analog low-frequency filter that generates a band-limited analog sound signal by allowing only the low-frequency band of the analog sound signal to pass; and an analog frequency shift for generating an ultrasonic analog sound signal by shifting the frequency band of the band-limited analog sound signal.

In addition, the receiving signal processing device includes an analog-to-digital converter that converts the amplified ultrasonic signal into a digital ultrasonic signal; A digital high-frequency filter that generates a band-limited digital ultrasound signal by allowing only the high-frequency band of the digital ultrasound signal to pass; Digital frequency shift for generating a digital sound signal by shifting the frequency band of the band-limited digital ultrasonic signal; And it may include a digital-to-analog converter that converts the digital sound signal into an analog sound signal.

In addition, the receiving signal processing device includes an analog high-frequency filter that generates a band-limited analog ultrasonic signal by allowing only the high-frequency band of the amplified ultrasonic signal to pass through; And it may include an analog frequency shift that generates an analog sound signal by shifting the frequency band of the band-limited analog ultrasonic signal.

In addition, the receiving signal processing device includes an analog-to-digital converter that converts the amplified ultrasonic signal into a digital ultrasonic signal; Digital frequency shift for generating a digital signal by shifting the frequency band of the digital ultrasonic signal; A digital low-frequency filter that generates a digital sound signal by allowing only the low-frequency band of the digital signal to pass through; And it may include a digital-to-analog converter that converts the digital sound signal into an analog sound signal.

In addition, the receiving signal processing device includes an analog frequency shift for generating an analog signal by shifting the frequency band of the amplified ultrasonic signal; And it may include an analog low-frequency filter that generates an analog sound signal by allowing only the low-frequency band of the analog signal to pass.

In addition, the transmitting radio wave device includes: an analog amplifier that amplifies an ultrasonic analog sound signal and generates an amplified ultrasonic analog sound signal; And it may include a speaker that broadcasts the amplified ultrasonic analog sound signal into the air.

In addition, the receiving radio wave device includes: an analog amplifier that amplifies an analog sound signal and generates an amplified analog sound signal; And it may include a speaker that transmits the amplified analog sound signal into the air.

Additionally, a transmitter placed at a specific location may include a case containing transmitter hardware; Speakers capable of emitting broadband sounds, including ultrasonic waves; Switch to select ultrasonic band or audible band; Dial to adjust sound volume; and a power system that supplies power.

In addition, the dual-channel receiving device worn by the user may include two independent receivers in a dual-channel configuration, two microphones placed at the same distance between the user's ears, and two speakers placed in front of the user's ears. You can.

Additionally, the single-channel receiving device used by the user may include an independent single-channel receiver, one microphone, and one speaker disposed at one end of the single-channel receiving device.

In addition, the dual-channel receiver in the form of glasses includes two temple bodies including two receivers; Right and left front rims of glasses that place two microphones; Two temples auricularis that place two speakers; And it may include two temple body bodies including a battery and a command switch.

In addition, the dual-channel receiving device in the form of a neckband includes two neckband wing bodies including two receivers; Right and left front ends of the neckband wings, which place two microphones; A neckband wing body at the bottom of the user's ears that places two speakers; and two neckband wing bodies containing a battery and a command switch.

In addition, the single-channel receiving device in a handheld form includes a handheld main body including one receiver; One side of the handheld to place one microphone; A handheld body that places one speaker; and a handheld body including a battery and a command switch.

In addition, the single channel receiving device in the form of a smartphone may include: a smartphone including one or more microphones, one or more speakers, and one or more switches; And it may include application software that implements the receiving signal processing device part in one receiver structure as software.

An ultrasonic sound guidance method for the visually impaired according to an embodiment of the present invention includes the steps of a user of a dual-channel receiver recognizing content transmitted from a speaker of the dual-channel receiver and confirming guidance information; Recognizing time and volume differences in sounds generated from the two speakers; Recognizing the direction of the transmitter by applying the time and magnitude difference using the human's binaural sound source direction measurement ability; Rotating the direction of the user and the dual-channel receiving device toward the transmitter; A user approaches the direction of the transmitter while maintaining equal time and loudness sounds from the two speakers; and recognizing that the user has arrived at the desired destination by recognizing the loudest sound from the two speakers.

An ultrasonic sound guidance method for the visually impaired according to an embodiment of the present invention includes the steps of the user of a single-channel receiver recognizing the content transmitted from the speaker of the single-channel receiver and confirming the guidance information; A user shaking the single channel receiver in a direction; Recognizing that the size of the sound generated from the speaker varies depending on the direction of the single-channel receiving device; a user recognizing the highest sound direction; Rotating the direction of the user and the single channel receiving device toward the transmitter; the user continuously performing the directional shaking action and approaching to move forward in the highest sound direction; and recognizing that the user has arrived at the desired destination by recognizing the loudest sound from the speaker.

As described above, according to the present invention, a visually impaired person can safely and efficiently find a desired destination and can avoid or recognize and act in places where safety is required. For example, if transmitters are installed in restrooms, elevators, and each room to broadcast ultrasonic sounds, a visually impaired person with a receiving device will be able to go directly to the restroom or room 307 as needed without using a direct Braille information board. Additionally, if a transmitter is installed at a construction site or on a staircase, visually impaired people can listen to the sound from the receiver and act appropriately and walk safely. Direction recognition through a receiving device can be recognized immediately by listening to the sound and measuring the direction of the sound source based on both ears in the case of a dual-channel receiving device. In the case of a single-channel receiving device, the sound volume changes according to direction by rotating the device. All you need to do is detect and recognize. The use of a cane is still necessary for visually impaired people to detect surrounding obstacles or walking conditions.

1 shows a simplified schematic block diagram of an ultrasonic acoustic guidance system for visually impaired people.
Figure 2 illustrates a simplified schematic block diagram of a transmitter.
Figure 3 shows the frequency distribution of individual transmitter blocks.
Figure 4 illustrates a simplified schematic block diagram of a receiver.
Figure 5 shows the frequency distribution of individual receiver blocks.
Figure 6 illustrates a simplified schematic block diagram of an alternative receiver.
Figure 7 illustrates the frequency distribution of individual receiver blocks for an alternative implementation.
Figure 8 shows an operation example for a dual-channel receiver to determine the location of a transmitter.
Figure 9 shows an example of operation for a single-channel receiver to determine the location of a transmitter.
Figure 10 illustrates an embodiment of a transmitter.
Figure 11 shows an embodiment of a glasses-type receiving device.
Figure 12 shows an example of wearing a glasses-type receiving device.
Figure 13 shows an embodiment of a neckband type receiving device.
Figure 14 shows an example of wearing a neckband type receiving device.
Figure 15 shows an embodiment of a handheld receiving device.
Figure 16 shows an example of use of a handheld type receiving device.
Figure 17 shows an example of a smartphone type receiving device.
Figure 18 shows an example of use of a smartphone type receiving device.

Preferred embodiments of the present invention will be described in detail with reference to the drawings attached below. Terms or words used in this specification and claims should not be construed as limited to their common or dictionary meanings, and the inventor may appropriately define the concept of terms in order to explain his or her invention in the best way. Based on the principle that it exists, it must be interpreted with meaning and concept consistent with the technical idea of this outbreak. Therefore, the embodiments described in this specification and the configurations shown in the drawings are only one of the most preferred embodiments of the present invention and do not represent the entire technical idea of the present invention, so various equivalents that can replace them at the time of filing the present application It should be understood that variations and variations may exist.

Ultrasonic sound guidance systems and methods provide acoustic information to visually impaired people based on ultrasound, allowing them to identify sound sources and determine their location. The sound source refers to an ultrasonic transmitter located at the intended destination during personal walking. Ultrasound is generated by shifting the frequency of the voice spectrum and continuously and selectively conveys location or guidance information. A receiving device carried by a visually impaired person receives ultrasonic waves and moves them back to audible frequencies to identify the location. Additionally, the intensity of audible sound depending on the direction and distance of the receiving device provides clues to locating the transmitter. Two receivers with a physical distance between the microphones can be configured as dual-channel receivers for improved localization capabilities. The output of the two speakers of the dual-channel receiver is delivered directly to each ear. The difference in the size and time of the arriving sound provides improved transmitter positioning performance based on the human ear-based sound source direction measurement ability. The ultrasonic acoustic guidance system uses inaudible ultrasonic waves to selectively transmit information to the receiver, reducing installation restrictions.

The physical structure of the transmitter can be freely designed as long as the speaker properly transmits ultrasonic waves. On the other hand, the physical structure of the receiving device requires careful design to maintain ambient spatial acoustic information for visually impaired people. The receiving device can be realized in a single or dual channel configuration. Each channel consists of receiver hardware, microphone, speaker, and battery, and each receiver has a power switch and charging port. Single-channel implementations can be designed with handheld devices and smartphones. In smartphone implementation, the role of a receiving device is performed by software using the smartphone's microphone and speaker without using additional hardware. The single-channel device can be attached to a cane or held in the hand. The dual-channel device can be implemented in the form of glasses and a neckband containing left and right channel receivers. The distance between the microphones in a dual-channel receiver should be approximately the same as the user's ear distance. The speaker output of the dual-channel receiver is provided directly to individual ears in an open structure. The dual-channel receiver not only provides spatial acoustic information from the transmitter but also maintains environmental acoustics for the user. Due to the typical acoustic signal overlapping characteristics, single and dual channel receivers can locate multiple transmitters. Users can determine the location of a specific transmitter by listening to various sounds from the receiver and following the desired sound intensity and time delay.

1 shows a simplified schematic block diagram of an ultrasonic acoustic guidance system for visually impaired people. The ultrasonic acoustic guidance system consists of a transmitter 100 and a receiver 200. The receiving device is a device formed based on the receiver 200 and is worn or carried by the user 300 to receive sound guidance. The transmitter 100 uses the speaker 101 to generate inaudible ultrasonic sound 150. The ultrasonic sound 150 propagates into the air and is received by the microphone 201 of the receiver 200. The receiver 200 transmits the ultrasonic sound 150 as audible sound 250 using the speaker 202. To identify and locate the transmitter, the visually impaired person 300 uses the receiver 200 together with the cane 350 to receive audible sound 250 information. Multiple receivers 200 may operate simultaneously to locate and identify multiple transmitters 100 indoors and outdoors. The ultrasonic sound 150 exhibits general acoustic characteristics, and therefore, the visually impaired 300 can hear multiple sounds superimposed on each other.

Figure 2 illustrates a simplified schematic block diagram of a transmitter. The transmitter 100 transmits acoustic information to the receiver 200 of FIG. 1. Acoustic information includes acoustic signals to identify a place or location, such as a room number. The analog acoustic signal is sampled and quantized by an analog-to-digital converter with f _s sampling rate (samples per second) and B bit resolution (bits per sample). The digital sound signal 102 is stored in digital memory. At a given 1/f _s time interval, a digital acoustic signal is transmitted from the digital memory via the digital communication line 103. The digital sound signal is processed by a low-frequency filter 104 to limit the bandwidth of the sound signal. The filtered acoustic signal is transmitted from the low-frequency filter 104 via a digital communication line 105. The filtered acoustic signal is shifted to the desired frequency range using a sinusoidal wave 107, for example αcos(ω _m n). α is the size control coefficient and ω _m is the frequency shift parameter. In digital signal processing, time is represented by the integer sequence number n, and real time is specified as n/f _s . ω _m Radian Frequency represents the frequency in the discrete time domain in radians per unit sample. The relationship between general frequency and radian frequency is as follows.

ω = 2πf/f _s f = ωf _s /(2π)

Time-domain multiplication (indicated by x in the diagram of FIG. 2) between the sinusoid 107 and the filtered acoustic signal in the frequency shift 106 performs a frequency shift for the desired frequency relocation. The shifted acoustic signal is transmitted from the frequency shift 106 using a digital communication line 108. The shifted sound signal is converted into an analog signal using a digital-to-analog converter 109. The analog signal is amplified by the amplifier 110. The amplified signal is converted into ultrasonic sound 150 using the speaker 101. The operating frequency range of the amplifier 110 and the speaker 101 must be extended to the desired ultrasonic bandwidth for accurate propagation of the ultrasonic sound 150. The transmission signal processing device 111 refers to a block including a low-frequency filter 104, a frequency shift 106, a digital-to-analog converter 109, and digital communication lines 105 and 108 connecting them. The transmission radio device 112 includes an amplifier 110 and a speaker 101. The transmission signal processing device 111 can be used by implementing the same function in analog form.

Figure 3 shows the frequency distribution of individual transmitter blocks. The x-axis 401 of each distribution diagram represents the frequency in radians, and the y-axis 400 of each distribution diagram specifies the absolute signal size at a given frequency. Due to the characteristics of the Discrete Fourier Transform, the frequency distribution shows even symmetry characteristics, and the upper audible frequency limit is generally 20 kHz. The individual distribution diagrams in Figure 3 show the ranges of audible and non-audible frequencies, respectively. The triangular shape 402 in the upper distribution diagram represents the frequency distribution in the digital sound signal 102 and the digital communication line 103 in FIG. 2. The pentagon shape 404 in the middle distribution diagram shows the frequency distribution of the filtered acoustic signal on the digital communication line 105 in FIG. 2. The rectangular dashed line 403 in the middle plot indicates the frequency response of the low-frequency filter 104 in Figure 2, which passes up to a frequency of ω _c radians. The two shifted pentagonal shapes 405 and 406 in the lower distribution diagram represent the frequency distribution of the shifted acoustic signal in the digital communication line 108 of FIG. 2. The frequency shift 106 in FIG. 2 is ω _m left and right with respect to the input sound. Frequency realignment is performed by moving the frequency in radians. Since it can be seen whether the shifted acoustic signal occupies the subaudible frequency range in the lower distribution diagram, no audible sound can be heard from the transmitter 100 of FIG. 2 to the normal human ear.

Figure 4 illustrates a simplified schematic block diagram of a receiver. The receiver 200 receives ultrasonic waves 150 containing sound information and converts them into audible sound 250 for the visually impaired. The microphone 201 receives the ultrasonic sound 150 and the amplifier 203 amplifies the received analog signal for later processing. The analog signal is sampled and quantized in real time by an analog-to-digital converter 204 with f _s sampling rate (samples per second) and B bit resolution (bits per sample). The digital ultrasonic signal is transmitted to the high-frequency filter 206 using a digital communication line 205. The high frequency filter 206 passes ultrasonic frequency signals and blocks the audible frequency range. The filtered ultrasonic signal is transmitted from the high frequency filter 206 through a digital communication line 207. The filtered ultrasonic signal is shifted to the desired frequency range using a sinusoidal signal 209, for example βcos(ω _m n). β is the size control coefficient and ω _m is the frequency shift parameter. Time-domain multiplication (indicated by x in the diagram of FIG. 4) between the sinusoidal wave 209 and the filtered ultrasound signal 207 in the frequency shift 208 performs a frequency shift for the desired frequency relocation. The shifted acoustic signal is conveyed from the frequency shift 208 using a digital communication line 210. The shifted sound signal is converted into an analog signal using a digital-to-analog converter 211. The analog signal is amplified by an amplifier 212, and the amplified signal is converted into audible sound 250 using a speaker 202. The receiving signal processing device 216 includes an analog-to-digital converter 204, a high-frequency filter 206, a frequency shift 208, a digital-to-analog converter 211, and digital communication lines 205, 207, and Names the block containing 210). The receiving radio wave device 217 includes an amplifier 212 and a speaker 202. The receiving signal processing device 216 may implement the same function in analog form. Because the receiver 200 must respond quickly for user safety, all operations must be performed in real time to minimize waiting time.

Figure 5 shows the frequency distribution of individual receiver blocks. The x-axis 401 of each distribution diagram represents the frequency in radians, and the y-axis 400 of each distribution diagram specifies the absolute signal size at a given frequency. The upper distribution diagram shows the frequency distribution of the digitized received signal on the digital communication line 205 of FIG. 4. The pentagonal shapes 407 and 408 are formed derived from signals propagated from the transmitter and occupy the subaudible frequency range. The widely distributed ripples 409 are broadband noise received from the surroundings and the microphone. It can be seen that the received noise 409 is partially removed from the intermediate distribution using the high-frequency filter 206 of FIG. 4, which passes frequencies above ω _c radians. The dashed line 410 in the middle plot provides the frequency response of the high-frequency filter 206 in FIG. 4. The pentagonal shape 411 in the lower distribution diagram indicates the frequency distribution of the signal shifted in the digital communication line 210 of FIG. 4. The frequency shift 208 of FIG. 4 performs frequency realignment by shifting the input signal by a left and right ω _m radian frequency. One of the moving directions of the middle distribution pentagonal shapes 407 and 408 in Figure 5 is rearranged and overlapped with the pentagonal shape 411 near the 0 radian frequency of the lower distribution. Certain noise may also be shifted near the 0 radian frequency and remain in the form of residual ripples 412. Because the shifted signal is included in the audible frequency range of the lower distribution chart, a visually impaired person can hear audible sound information from the receiver 200 of FIG. 4.

Figure 6 illustrates a simplified schematic block diagram of an alternative receiver. In the receiver 200, the microphone 201 receives the ultrasonic sound 150, and the amplifier 203 amplifies the received analog signal for later processing. The analog signal is sampled and quantized in real time by the analog-to-digital converter 204. The digital ultrasound signal is transmitted to the frequency shift 208 using a digital communication line 205. The digital ultrasound signal is shifted to the desired frequency range using a sinusoidal signal 209, for example βcos(ω _m n). Time-domain multiplication (indicated by x in the diagram of FIG. 6) between the sinusoidal wave 209 and the digital ultrasound signal 205 in the frequency shift 208 performs a frequency shift for the desired frequency relocation. The shifted acoustic signal is conveyed from frequency shift 208 using digital communication lines 214. The low-frequency filter 213 passes audible frequency signals and blocks high-frequency components. The filtered acoustic signal is transmitted from the low-frequency filter 213 through a digital communication line 215. The filtered sound signal is converted into an analog signal using a digital-to-analog converter 211. The analog sound signal is amplified by the amplifier 212. The amplified signal is converted into audible sound 250 using a speaker 202. An alternative receiver implementation includes a low frequency filter 213 in place of the high frequency filter 206 of Figure 4 and uses a shifted frequency shifter 208. An alternative receiving signal processing device 218 includes an analog-to-digital converter 204, a frequency shift 208, a low-frequency filter 213, a digital-to-analog converter 211, and digital communication lines 205, 214 connecting them. , and 215). The receiving radio wave device 217 includes an amplifier 212 and a speaker 202. The alternative receiving signal processing device 218 can be used by implementing the same function in analog form.

Figure 7 illustrates the frequency distribution of individual receiver blocks for an alternative implementation. The x-axis 401 of each distribution diagram represents the frequency in radians, and the y-axis 400 of each distribution diagram specifies the absolute signal size at a given frequency. The upper distribution diagram shows the frequency distribution of the digitized received signal on the digital communication line 205 in FIG. 6. The pentagonal shapes 407 and 408 are formed derived from signals propagated from the transmitter and occupy the subaudible frequency range. The widely distributed ripples 409 are broadband noise received from the surroundings and the microphone. The pentagon shape 413 in the middle distribution diagram represents the frequency distribution of the signal shifted on the digital communication line 214 in FIG. 6. The frequency shift 208 of FIG. 6 performs frequency realignment by moving the input signal by a left and right ω _m radian frequency. One of the moving directions of the upper distribution pentagonal shapes 407 and 408 in Figure 7 is rearranged and overlapped with the pentagonal shape 413 near the 0 radian frequency of the middle distribution. It can be seen that the shifted noise 409 has been removed from the lower distribution diagram using the low-frequency filter 213 of FIG. 6, which passes frequencies below ω _c radians. The rectangular dotted line 414 in the bottom distribution diagram provides the frequency response of the low-frequency filter 213 in FIG. 6. Since the noise-removed and shifted signal 415 is included in the audible frequency range of the lower distribution chart, a visually impaired person can hear audible sound information from the receiver 200 of FIG. 6.

Figure 8 shows an operation example for a dual-channel receiver to determine the location of a transmitter. A dual-channel receiver refers to a device that performs processing from two microphones to two speakers with two independent receivers. In the individual microphone, each channel performs the receiver operation shown in Figure 4 or Figure 6 to transmit audible acoustic information using an individual speaker. The distance between the microphones is the same as the distance between your ears. Speakers are placed near each ear in an open structure so that differences in sound size and time delay of each channel can be recognized. To maintain acoustic perception of the surrounding space for visually impaired people, the acoustic flow to the ear should not be blocked by the receiving device. Figure 8 shows a method of processing sound guidance by a user based on a dual-channel receiver. The three pictures are displayed in chronological order from left to right. The left, middle, and right pictures contain the same configuration as shown below. The transmitter 100 broadcasts ultrasonic waves 150 using the speaker 101. The ultrasonic waves 150 are propagated into the air, and the transmission surface of the ultrasonic waves exhibits the characteristics of a plane wave 301 at a long distance. The visually impaired person 300 holds a dual-channel receiver parallel to the line made between the ears. The dual-channel receiving device has a symmetrical structure and includes two microphones 201, two receivers 200, and two speakers 202. The receiver speaker 202 is located near the individual ears of the visually impaired person 300. In the left figure, the user 300 is located indirectly and at a distance and receives audible sound 250 from the transmitter 100 for location identification. User 300 experiences audible sound 250 differences between receiver speakers 202 due to the orientation of the dual-channel receiver. The direct distance difference 302 between the speaker 101 and the microphone 201 creates an audible sound 250 difference in loudness and delay time. The human's binaural-based sound source direction measurement ability recognizes the direction of the transmitter speaker 101, and the user 300 turns his body toward the transmitter 100 in the middle figure. The user 300 in the middle picture is facing the transmitter 100 and experiences audible sound 250 of uniform size and delay time from the receiver speaker 202. The user 300 in the picture on the right approaches the transmitter 100 to receive a larger-sized audible sound 250, and the user recognizes that he has reached his destination.

Figure 9 shows an operation example in which a single-channel receiver determines the location of a transmitter. A single channel receiver refers to a receiver with a single microphone and a single speaker. The single-channel receiver is carried in the user's hand or attached to a cane. The physical directional rocking behavior of a single-channel receiver creates audible loudness differences depending on receiver orientation and distance from the transmitter. Figure 9 shows a method of processing sound guidance by a user based on a single-channel receiving device. The three pictures are displayed in chronological order from left to right. The left, middle, and right pictures contain the same configuration as shown below. The transmitter 100 broadcasts ultrasonic waves 150 using the speaker 101. The ultrasonic waves 150 are propagated into the air, and the transmission surface of the ultrasonic waves represents a plane wave 301 at a long distance. The visually impaired 300 holds or installs a single-channel receiving device in the user's hand or cane. The single-channel receiving device includes a microphone 201, a receiver 200, and a speaker 202. In the left figure, the user 300 is located indirectly and at a distance and receives audible sound 250 from the transmitter 100 for location identification. User 300 initiates a receiver shaking action 303 and experiences an audible sound 250 difference from receiver speaker 202 due to receiver orientation. When the user 300 recognizes the direction of the highest volume, the user 300 turns its body toward the transmitter 100 in the middle picture. The user 300 in the middle picture faces the transmitter 100 and continuously performs a small directional shake action 303 to find the loudest audible sound 250 from the receiver speaker 202. The user 300 in the picture on the right approaches the transmitter 100 to receive a larger-sized audible sound 250, and the user recognizes that he has reached his destination.

Figure 10 illustrates an embodiment of a transmitter. The physical structure of the transmitter can be implemented in a variety of formats and this figure shows an example of an implementation. The transmitter is protected by a durable case 500 that contains the circuit board and power system inside. Transmitter speaker 101 is located below the acoustic hole of case 500. The transmitter may have an acoustic guide ring 501 at the edge of the speaker diaphragm to control ultrasonic sound directivity. The sound mode switch 502 selects the output sound between audible sound mode and ultrasonic mode to test the transmitter with normal sound. Volume knob 504 adjusts the level of ultrasonic and audible sound from transmitter speaker 101. Power switch 503 turns the transmitter system on and off. LED light emitting diode 505 indicates the power status of the transmitter.

Figure 11 shows an embodiment of a receiving device in the form of glasses. The glasses-shaped receiving device 600 presents one implementation of a dual-channel receiving device. A spectacle-type receiver includes each channel receiver in a symmetrical fashion on individual temples. The two microphones 201 of the receiving device are located on the right and left sides of the front edge (rim) of the glasses-shaped receiving device. Receiver hardware 200 and battery system 601 are disposed within the temples of a spectacle-type receiver. The two speakers 202 of the receiving device are located at the back of the temples of the glasses near the user's ears. The charging port 603 is located on one temple of the glasses-type receiver, and the power switch 602 is located on the other temple.

Figure 12 shows an example of wearing a glasses-type receiving device. A visually impaired person (300) wears a glasses-type receiving device (600) and holds a cane (350) in one hand. Only one side of the glasses-type receiver is shown in the picture, and the other side is symmetrical and identical. Two microphones 201 of the glasses-type receiver receive ultrasonic waves 150 from the transmitter. The receiving device converts the ultrasonic sound 150 into audible sound 250 emitted by the receiving device speaker 202. A method for locating and accessing a transmitter based on a dual-channel receiver is explained and shown in FIG. 8.

Figure 13 shows an embodiment of a neckband type receiving device. The neckband type receiving device 700 presents one implementation of a dual channel receiving device. The individual wings of the neckband-type receiver contain each channel receiver in a symmetrical manner. The two microphones 201 of the receiving device are located on the right and left sides of the front end of the neckband wings. Receiver hardware 200 and battery system 701 are disposed within neckband-type receiver wings. The two speakers 202 of the receiving device are located on the wing body of the neckband at the bottom of the user's ears. The charging port 703 and the power switch 702 are placed at any location in the neckband type receiving device.

Figure 14 shows an example of wearing a neckband type receiving device. A visually impaired person (300) wears a neckband-type receiving device (700) and holds a cane (350) in one hand. Only one side of the neckband type receiver is shown in the picture, the other side is symmetrical and identical. Two microphones 201 of the neckband type receiving device receive ultrasonic waves 150 from the transmitter. The receiving device converts the ultrasonic sound 150 into audible sound 250 emitted by the receiving device speaker 202. A method for locating and accessing a transmitter based on a dual-channel receiver is explained and shown in FIG. 8.

Figure 15 shows an embodiment of a handheld receiving device. Handheld receiving device 800 represents one implementation of a single channel receiving device. In the handheld type receiving device, one microphone 201 is located in the front of the receiving device. The receiver hardware 200 and battery system 801 are disposed within the main body of the handheld receiver. In the handheld type receiving device, one speaker 202 is located at the rear of the receiving device. A single-channel receiver uses directional waving behavior to estimate the transmitter location. Therefore, the speaker can be inserted in any position as long as the user can hear audible sound. Additional information about directional shaking behavior can be found in Figure 9. The charging port 803 and the power switch 802 may be placed in any location of the handheld type receiving device.

Figure 16 shows an example of use of a handheld type receiving device. The handheld receiver can be used as a device attached to a cane or as a stand-alone device in the user's hand. The left and right views of Figure 16 show examples of attached and stand-alone device modes, respectively. The attachment mode controls the movement of the wand to create a directional waving behavior. In stand-alone device mode, the user holds the wand in one hand and the handheld receiver in the other. Directional shaking behavior is produced by horizontal hand movements. The left and right views of FIG. 16 show the same configuration except for the location of the handheld receiver. The visually impaired 300 uses the handheld receiving device 800 in the attached device mode shown on the left and the independent device mode shown on the right. A visually impaired person (300) must hold a cane (350) in one hand. One microphone 201 of the handheld receiving device receives ultrasonic sound 150 from the transmitter. The receiving device converts the ultrasonic sound 150 into audible sound 250 emitted by the receiving device speaker 202. A method for locating and accessing a transmitter based on a single-channel receiver is explained and shown in FIG. 9.

Figure 17 shows an example of a smartphone type receiving device. The smartphone type receiving device 900 presents one implementation of a single channel receiving device. The smartphone-type receiving device utilizes smartphone hardware and uses application software to implement a single-channel receiving device. There is no need for additional hardware attached to the smartphone-type receiving device. The smartphone's single or multiple microphones 201 are configured as receiver microphones. The single or multiple speakers 202 of the smartphone are used as receiver speakers. In the single-channel receiving device structure, application software that implements the receiving signal processing device (216 or 218) in software is applied. Because single-channel receivers use directional waving behavior to estimate transmitter location, the speaker can be placed in any location as long as the user can hear audible sound. Additional information about directional shaking behavior can be found in Figure 9. Charging port 902 can be used for battery charging and multiple switches 901 can be used for power and volume control.

Figure 18 shows an example of use of a smartphone type receiving device. The smartphone-type receiver can be used as a device attached to a cane or as a stand-alone device in the user's hand. The left and right views of Figure 18 show examples of attached and stand-alone device modes, respectively. The attachment mode controls the movement of the wand to create a directional waving behavior. In stand-alone device mode, the user holds the wand in one hand and a smartphone-type receiver in the other. Directional shaking behavior is produced by horizontal hand movements. The left and right drawings of FIG. 18 show the same configuration except for the location of the smartphone-type receiving device. The visually impaired 300 uses the smartphone-type receiving device 900 in the attached device mode shown on the left and the independent device mode shown on the right. A visually impaired person (300) must hold a cane (350) in one hand. A single or multiple microphone 201 of a smartphone-type receiving device receives ultrasonic sound 150 from a transmitter. The receiving device converts the ultrasonic sound 150 into audible sound 250 emitted by the receiving device speaker 202. A method for locating and accessing a transmitter based on a single-channel receiver is explained and shown in FIG. 9.

As above, although the present invention has been described with limited examples and drawings, the scope of the present invention is not limited thereto, and the technical idea and claims of the present invention can be understood by those skilled in the art to which the present invention pertains. Of course, various modifications and variations are possible within the range of equality.

100: Transmitter
101: Transmitter speaker
102: Digital sound signal (digital memory)
103: Digital communication line (digital sound signal (102) -> low frequency filter (104))
104: Low-frequency filter
105: Digital communication line (low frequency filter (104) -> frequency shift (106))
106: Frequency shift
107: Sine wave
108: Digital communication line (frequency shift (106) -> digital-to-analog converter (109))
109: Digital-to-analog converter
110: amplifier
111: Transmission signal processing device
112: Transmission radio device
150: Ultrasonic sound (inaudible)
200: receiver
201: Receiver microphone
202: Receiver speaker
203: amplifier
204: Analog-to-digital converter
205: Digital communication line (analog-digital converter (204) -> high frequency filter (206))
206: high frequency filter
207: Digital communication line (high frequency filter (206) -> frequency shift (208))
208: Frequency shift
209: Sine wave
210: Digital communication line (frequency shift (208) -> digital-analog converter (211))
211: Digital-to-analog converter
212: amplifier
213: Low-frequency filter
214: Digital communication line (frequency shift (208) -> low frequency filter (213))
215: Digital communication line (low frequency filter (213) -> digital-analog converter (211))
216: Receiving signal processing device
217: Receiving radio device
218: Alternative reception signal processing device
250: Audible sound
300: Visually impaired or user
301: Far-field plane wave of ultrasound broadcast from a transmitter
302: Difference in straight line distance from each receiver microphone to the transmitter in a dual-channel receiver
303: Directional shaking action
350: Staff
400: Frequency distribution y-axis absolute signal size
401: Frequency distribution chart x-axis radian frequency
402: Recorded digital sound frequency distribution
403: Low-frequency filter frequency response distribution
404: Low-frequency filtered digital acoustic frequency distribution
405: Low-frequency filtered and frequency-shifted digital acoustic frequency distribution on one side
406: Low-frequency filtered and frequency-shifted digital acoustic frequency distribution on the other side
407: Distribution of ultrasonic sound frequencies on one side received by the microphone of the receiving device
408: Distribution of ultrasonic sound frequencies received by the microphone of the receiving device
409: Broadband noise frequency distribution received by the microphone of the receiving device
410: High-frequency filter frequency response distribution
411: High-frequency filtered and frequency-shifted received digital acoustic frequency distribution
412: High-frequency filtered and frequency-shifted received digital noise frequency distribution
413: Frequency shifted received digital sound frequency distribution
414: Low-frequency filter frequency response distribution
415: Frequency shifted and low frequency filtered received digital acoustic frequency distribution
500: Transmitter case
501: Acoustic guide ring
502: Sound mode switch
503: Transmitter power switch
504: Transmitter volume knob
505: Transmitter power LED emitting diode
600: Glasses-type receiving device
601: Battery system
602: Power switch
603: Charging port
700: Neckband type receiving device
701: Battery system
702: Power switch
703: Charging port
800: Handheld receiving device
801: Battery system
802: Power switch
803: Charging port
900: Smartphone type receiving device
901: Multiple switches
902: Charging port

Claims (18)

In the ultrasonic acoustic guidance system,
A transmitter 100 that modulates the recorded audible sound into an ultrasonic signal and broadcasts the ultrasonic sound;
a receiver 200 that receives the ultrasonic broadcast, converts it to an audible frequency, and generates the recorded audible sound; and
A single-channel or dual-channel receiving device configured to include one or two receivers (200);
Including,
Transmitter 100,
A digital memory 102 that stores recorded digital sound signals;
A transmission signal processing device 111 that receives the recorded digital sound signal and converts it into an ultrasonic analog sound signal; and
A transmission propagation device 112 that broadcasts the ultrasonic analog sound signal into the air;
Includes, and
The receiver 200 is,
A microphone 201 that receives the ultrasonic broadcast transmitted from the transmitter 100 and generates an ultrasonic signal;
an analog amplifier 203 that amplifies the received ultrasonic signal and generates an amplified ultrasonic signal;
a receiving signal processing device (216 or 218) that modifies the amplified ultrasonic signal to restore an analog sound signal transmitted from the transmitter (100); and
A reception propagation device 217 that propagates the analog sound signal into the air;
Ultrasonic acoustic guidance system for the visually impaired, comprising: According to claim 1,
The transmission signal processing device 111,
A digital low-frequency filter (104) that generates a band-limited digital sound signal by allowing only the low-frequency band of the recorded digital sound signal to pass through;
A digital frequency shift 106 that generates an ultrasonic digital sound signal by shifting the frequency band of the band-limited digital sound signal; and
A digital-to-analog converter (109) that converts the ultrasonic digital sound signal into an ultrasonic analog sound signal;
Ultrasonic acoustic guidance system for the visually impaired, comprising: According to claim 1,
The transmission signal processing device 111,
a digital-to-analog converter that converts the recorded digital sound signal into an analog sound signal;
an analog low-frequency filter that generates a band-limited analog sound signal by allowing only the low-frequency band of the analog sound signal to pass; and
Analog frequency shift for generating an ultrasonic analog sound signal by shifting the frequency band of the band-limited analog sound signal;
Ultrasonic acoustic guidance system for the visually impaired, comprising: According to claim 1,
The receiving signal processing device 216,
An analog-to-digital converter 204 that converts the amplified ultrasonic signal into a digital ultrasonic signal;
A digital high-frequency filter 206 that generates a band-limited digital ultrasound signal by allowing only the high-frequency band of the digital ultrasound signal to pass through;
A digital frequency shift 208 that generates a digital sound signal by shifting the frequency band of the band-limited digital ultrasonic signal; and
A digital-to-analog converter 211 that converts the digital sound signal into an analog sound signal;
Ultrasonic acoustic guidance system for the visually impaired, comprising: According to claim 1,
The receiving signal processing device 216,
an analog high-frequency filter that generates a band-limited analog ultrasonic signal by allowing only the high-frequency band of the amplified ultrasonic signal to pass; and
Analog frequency shift for generating an analog sound signal by shifting the frequency band of the band-limited analog ultrasonic signal;
Ultrasonic acoustic guidance system for the visually impaired, comprising: According to claim 1,
The receiving signal processing device 218,
An analog-to-digital converter 204 that converts the amplified ultrasonic signal into a digital ultrasonic signal;
A digital frequency shift 208 that generates a digital signal by shifting the frequency band of the digital ultrasonic signal;
A digital low-frequency filter 213 that generates a digital sound signal by allowing only the low-frequency band of the digital signal to pass through; and
A digital-to-analog converter 211 that converts the digital sound signal into an analog sound signal;
Ultrasonic acoustic guidance system for the visually impaired, comprising: According to claim 1,
The receiving signal processing device 218,
Analog frequency shift for generating an analog signal by shifting the frequency band of the amplified ultrasonic signal; and
an analog low-frequency filter that generates an analog sound signal by allowing only the low-frequency band of the analog signal to pass;
Ultrasonic acoustic guidance system for the visually impaired, comprising: According to claim 1,
The transmitting propagation device 112,
An analog amplifier 110 that amplifies an ultrasonic analog sound signal and generates an amplified ultrasonic analog sound signal; and
A speaker 101 that broadcasts an amplified ultrasonic analog sound signal into the air;
Ultrasonic acoustic guidance system for the visually impaired, comprising: According to claim 1,
The receiving radio wave device 217,
An analog amplifier 212 that amplifies an analog sound signal and generates an amplified analog sound signal; and
A speaker 202 that transmits an amplified analog sound signal into the air;
Ultrasonic acoustic guidance system for the visually impaired, comprising: According to claim 1,
Transmitter 100,
Case 500 containing transmitter hardware;
A speaker (101) capable of emitting a broadband sound including ultrasonic waves;
Switch 502 for selecting ultrasonic band or audible band;
Dial 504 for adjusting sound volume; and
a power system that supplies power;
Ultrasonic acoustic guidance system for the visually impaired, comprising: According to claim 1,
The dual-channel receiving device worn by the user is,
Two independent receivers 200 in a dual-channel configuration,
Arrange two microphones 201 at the same distance between the user's ears,
An ultrasonic acoustic guidance system for the visually impaired, comprising placing two speakers (202) in front of the user's ears. According to claim 1,
The single channel receiving device used by the user is,
One independent receiver (200) with a single-channel configuration,
An ultrasonic sound guidance system for the visually impaired, comprising arranging one microphone (201) and one speaker (202) at one end of the single-channel receiver. According to claim 11,
The dual-channel receiving device 600 in the form of glasses,
Two temple bodies containing two receivers (200);
Right and left front rims of glasses (rims) that place two microphones 201;
two temples on the auricular side, placing two speakers 202; and
Two temple body bodies including a battery 601 and a command switch 602;
Ultrasonic acoustic guidance system for the visually impaired, comprising: According to claim 11,
The dual-channel receiving device 700 in the form of a neckband,
Two neckband wing bodies containing two receivers (200);
a right and left front ends of the neckband wings that place two microphones 201;
A neckband wing body at the bottom of the user's ears that places two speakers 202; and
Two neckband wing bodies containing a battery (701) and a command switch (702);
Ultrasonic acoustic guidance system for the visually impaired, comprising: According to claim 12,
The single-channel receiving device 800 in a handheld form,
A handheld body including one receiver (200);
One side of the handheld to place one microphone (201);
A handheld body placing one speaker (202); and
A handheld body including a battery 801 and a command switch 802;
Ultrasonic acoustic guidance system for the visually impaired, comprising: According to claim 12,
The single channel receiving device 900 in the form of a smartphone,
A smartphone including one or more microphones (201), one or more speakers (202), and one or more switches (901); and
Application software that implements the receiving signal processing device (216 or 218) in one receiver structure as software;
Ultrasonic acoustic guidance system for the visually impaired, comprising: The dual-channel receiving device user 300,
A step of the user recognizing the content transmitted from the dual-channel receiver speaker 202 and confirming the guidance information;
Recognizing time and volume differences in sounds generated from the two speakers 202;
Recognizing the direction of the transmitter 100 by applying the time and magnitude difference using the human's binaural sound source direction measurement ability;
Rotating the direction of the user and the dual-channel receiving device toward the transmitter 100;
A user approaches the direction of the transmitter 100 while maintaining equal time and volume sound generation from the two speakers 202; and
Recognizing that the user has arrived at the desired destination by recognizing the loudest sound from the two speakers 202;
Ultrasonic sound guidance method for the visually impaired, comprising: The single channel receiving device user 300,
A step of the user recognizing the content transmitted from the single-channel receiver speaker 202 and confirming the guidance information;
A user shaking the single channel receiver in a direction;
Recognizing that the size of the sound generated from the speaker 202 varies depending on the direction of the single channel receiving device;
a user recognizing the highest sound direction;
Rotating the direction of the user and the single channel receiving device toward the transmitter 100;
the user continuously performing the directional shaking action and approaching to move forward in the highest sound direction; and
Recognizing that the user has arrived at the desired destination by recognizing the loudest sound from the speaker 202;
Ultrasonic sound guidance method for the visually impaired, comprising: