WO1995004440A1

WO1995004440A1 - Remotely controlled, infrared beacon system for guiding the visually impaired

Info

Publication number: WO1995004440A1
Application number: PCT/US1994/008463
Authority: WO
Inventors: Michael B. Hancock
Original assignee: Board Of Regents, The University Of Texas System
Priority date: 1993-07-28
Filing date: 1994-07-28
Publication date: 1995-02-09
Also published as: AU7374294A

Abstract

A remote controlled infrared beacon system enables blind individuals to be self-guiding toward desired destinations. A code is entered via keypad (14) and encoder (42) of a hand-held transceiver (10) which emits a pulse code modulated interrogation signal (20) via a radio transmitter (43), thereby selectively activating an infrared beacon unit (13) corresponding to a desired location using a receiver (44), decoder (45), oscillator (46) and infrared light emitting diodes (47). A directional infrared lens (48) and receiver/decoder (49) in the transceiver (10) are used to scan the horizontal plane to locate or home in on the infrared signal (22). An amplifier (50) drives a vibrator (51) to signal the user that the beacon (13) has been directionally located. Multiple beacons (1, 3, 8, 9) are employed to establish paths which may be followed by serially activating successive beacons to navigate to a desired destination.

Description

DESCRIPTION

REMOTELY CONTROLLED, INFRARED BEACON SYSTEM FOR GUIDING THE VISUALLY IMPAIRED

BACKGROUND OF THE INVENTION

The present invention is an electronic "navigation" system for guiding visually impaired individuals so that they may achieve greater independence in reaching desired destinations or targets, particularly in unfamiliar public buildings.

Over the past many years, various methods and systems have been devised to aid the blind in guiding themselves through unfamiliar surroundings. From such early and crude devices as the walking cane have evolved electronic systems that provide audio stimuli as guide indicators. For example, traffic signals which produce musical sounds for the blind have been developed. More sophisticated systems have also evolved, such as that disclosed by Osaka, U.S. Patent No. 4,660,022, in which the user carries a transmitter control unit to activate location indicators. By actuating the transmitter control unit, the user causes a control signal to be transmitted to a receiver that is placed near a desired location. Upon reception of a control signal, the receiver emits an audio signal. From the direction and intensity of the audio signal, the user may determine the direction and location of the desired destination. Although this system may effectively guide the user toward a desired destination, it has a significant drawback in that a loud audio signal is produced at the target, which may be distracting to others in the vicinity, difficult to localize due to interfering noise, and cannot be used by deaf-blind individuals.

Another system for guiding the blind includes a hand-held device that emits a light beam, such as that disclosed by Ban et al . , U.S. Patent No. 4,648,710. Photoreflectors are strategically placed to guide the user toward a desired destination. The user points the hand-held transmitter, which contains a light-emitting device, at the reflectors (generally by scanning the device horizontally in a forward direction) . Once the light beam hits a reflector, it is reflected back toward the transmitter. The transmitter then signals reception of a reflected beam either by sounding a buzzer or by activating a vibrating element. One disadvantage of this system is its dependency on the accuracy of reflected light, which may suffer from interference of ambient light. Further, no provision is made for distinguishing targets.

Thus, a need exists for a system for guiding the blind that will not distract others, but will provide a reliable means of guiding the user to a variety of facilities in unfamiliar surroundings.

SUMMARY OF THE INVENTION

The problems outlined above are addressed by the devices and method of the present invention. The present invention provides visually impaired persons, or other persons needing guidance, with a system of beacons for locating desired destinations or targets, such as telephones, rest rooms, doorways, or elevators.

The system comprises a portable, battery-powered, hand-held transceiver that transmits a pulse-code modulated (PCM) radio frequency (RF) interrogation signal, and receives a modulated infrared (IR) response signal emitted by a fixed beacon. Each beacon is equipped with an RF receiver and a decoder, and if a transmitted RF code matches the particular code that is preset in the beacon decoder, then IR light-emitting diodes (LEDs) are switched on. The LEDs are modulated by an on-board oscillator.

The modulated IR light signal emitted by the beacon is detected by an IR receiver/decoder, which is preferably mounted behind a cylindrical lens to make the IR receiver highly directional in the horizontal plane. Detection of the IR light signal from the beacon activates an indicating means, such as a vibrator, in the hand-held transceiver. A vibrator is a preferred indicating means for use by both blind and deaf individuals. Other suitable indicating means for hearing individuals include tone generators, such as beepers, buzzers and voice synthesizers.

To seek a desired destination, the user "locks" onto the IR signal from a beacon and tracks it to the beacon, and thus to a desired destination (or along a route to the destination) . A uniform system of codes is preferably used, so that particular facilities { e . g. , elevators, water fountains) always have the same code in each building. If the desired destination is not in immediate "line-of-sight" of the user, then intermediate beacons with different codes may be sequentially activated by the user so that the user can navigate to the desired destination. A directory listing codes for individual destinations in a particular building is preferably provided. For blind users, a Braille "guide book" or audio tape listing the facilities available, along with their corresponding codes, would preferably be provided. Thus, the present invention provides a uniform system for enabling the blind to guide themselves through public buildings and other environments reliably, with only a minimum amount of modification to existing structures required. The hand-held transceivers may be provided at low cost, and are easily portable within a pocket, purse, backpack, etc. Moreover, because the transceivers themselves (and not the beacons) generate a vibration or low-level sound to indicate successful interrogation of a beacon, the system is not distracting to other individuals in the vicinity.

BRIEF DESCRIPTION OF THE DRAWINGS

The herein described advantages and features of the present invention, as well as others which will become apparent, are attained and can be understood in more detail by reference to the following description and appended drawings, which form a part of this specification.

It is to be noted, however, that the appended drawings illustrate only exemplary embodiments of the invention and are therefore not to be considered limiting of its scope, for the invention may admit to other equally effective embodiments.

FIG. 1 is a plan view of a hand-held transceiver according to the present invention.

FIG. 2 is a block diagram of a guidance system according to the present invention.

FIG. 3 is a schematic diagram of a 40 KHz oscillator used to modulate infrared LEDs in beacons according to the present invention. FIG. 4 is a schematic diagram of a circuit linking an infrared receiver/decoder module with an indicating means according to the present invention.

FIG. 5 is a diagram illustrating how the system of the present invention may be used to guide a visually impaired user.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Turning now to details of the drawings, FIG. 1 illustrates a portable, battery-powered, hand-held transceiver 10 according to the present invention. Transceiver 10 preferably includes plastic case 11, power switch 12, keypad 14, and cylindrical lens 16 covering IR reception port 18.

Keypad 14 may be used to choose a pulse-code interrogation signal assigned to a specific beacon. For example, the number "5" on the keypad may be designated for "water fountains" in the guidance system. Accordingly, by depressing the "5" key, the user will cause the transceiver to transmit a pulse-modulated RF interrogation signal to activate beacons located over water fountains that are within range (approximately 100 ft. for the components described herein) of RF transmitter 43 (shown in FIG. 2) .

A telephone-type layout is preferably used for keypad 14, since most blind individuals are familiar with that arrangement. The numerals and symbols on keypad 14 could also be embossed in Braille or other ways for easy touch-based identification.

FIG. 2 shows a block diagram of components of a guidance system according to the present invention. Power for hand-held, portable transceiver 10 may be supplied by a nickel-cadmium, rechargeable battery pack (such as that manufactured by Allied Electronics, model 621-1135) , and power for each beacon 13 may be supplied by a 150 mA, 12 volt AC-to-DC adapter.

In a preferred method of guidance according to the present invention, the user initiates the guidance process by holding down one of the keys 15 on numerical keypad 14 that corresponds to a desired beacon 13. When an appropriate key 15 is depressed, a specific pin on encoder 42 integrated circuit is grounded and transmitter 43 is pulsed on in a specific selected sequence. The transmitted RF signal 20 is detected by superheterodyne RF receiver 44 located in each beacon 13. Each beacon 13 is precoded with a switch array on the decoder board 45, and an incoming RF interrogation signal 20 is compared with the preset code. If decoder 45 in beacon 13 receives a pulse sequence that matches the sequence preset for that beacon, power is then applied to oscillator 46 (see FIG. 3) , which drives a collection of infrared (IR) light-emitting diodes 47 to generate response signal 22.

In transceiver 10, cylindrical lens 48, which may comprise a 1" length of 1" diameter Plexiglas™ rod, oriented vertically, directs light onto a photodiode located in infrared receiver/decoder module 49. Cylindrical lens 48 makes IR receiver/decoder 49 highly directional in the horizontal plane, but not in the vertical plane. Thus, accurate scanning is not dependent on the user's height or the physical position of the beacon with respect to the floor. However, the horizontal bandwidth will be narrow so that the user will be guided toward the beacon within "line of sight." By continually scanning the horizon and moving forward in the direction indicated by the transceiver, the user may track the IR light to its source. When infrared light (modulated at 40 KHz for the components described in Table 1) is detected by IR receiver/decoder 49 in transceiver 10, single stage transistor amplifier 50, which is electronically coupled to IR receiver/decoder 49, is activated. Amplifier 50, in turn, powers an indicating means, shown in FIG. 2 as vibrator 51. For the embodiment described herein, the IR light from beacon 13 is modulated at 40 KHz, since the IR receiver/decoder module used in the embodiment contains a 40 KHz band-pass filter. Other combinations will be apparent to those of skill in the art.

FIG. 3 is a schematic diagram of 40 KHz driver/oscillator 46 used to modulate infrared LEDs in beacons according to the present invention. Oscillator 46 comprises 5-volt voltage regulator 60, and oscillator 62. Voltage is applied to regulator 60 and modulated by oscillator 62 to drive IR LED's 47 (LI and L2) . For 40 KHz oscillation, the values for the components of FIG. 3 may be selected as indicated below in Table 1.

FIG. 4 is a schematic diagram of a circuit linking an infrared receiver/decoder module with an indicating means according to the present invention. IR response signal 22 is detected by receiver/demodulator 49. The output of receiver/demodulator 49 is amplified by amplifier 50 (comprising R3, R4, and Tl) to drive vibrator 51, thus to indicate to the user that a beacon has been successfully interrogated by transceiver 10. Suitable components for the circuit shown in FIG. 4 are provided in Table 1.

In a preferred method of operation, illustrated in FIG. 5, the user enters a facility such as a building. Assume that the "1" key on the transceiver keypad is the standard designator for "directory." As the user enters the building, he or she depresses the "1" key and scans horizontally until a vibration is perceived, and then proceeds to a directory near the building entrance. The directory could be provided in Braille print or on an audio tape, or both, and would provide the user with a listing of coded facilities within the building. A designator sequence after each listing is preferably used to navigate from the directory to the desired destination. For example, if the user wished to locate an elevator, and the elevator has the designator "8," he or she would search the directory for word "elevator."

In this example, the elevator is not in immediate line of sight from the directory. Thus, a guided path is required. Accordingly, the user would be given the designator sequence "3-9-8," where beacons "3" and "9" are intermediate beacons for this route, and "8" is the destination beacon located over the elevator. The user would depress the "3" key until he or she reached the activated beacon, then release the "3" key and depress the "9" key to reach the next intermediate beacon. Because receipt of an IR response signal is highly ' directional in a forward direction, proximity to a beacon is determined by a loss of signal as the user passes under the beacon. The user then knows to release the key for that beacon and select the next key in the designator sequence. In the present example, as the user passes the last intermediate stage "9," the user would be guided to the final beacon over the elevator by releasing the "9" key and depressing the "8" key.

It is preferred that the beacons be located on the ceiling or high on a wall to reduce the likelihood of other individuals blocking the infrared light coming from a beacon.

Table 1 below lists component values for the electronic components of FIGs. 1-4. It is to be understood, however, that certain of these component values may be different for a given implementation of the present invention, and the values in Table 1 are provided only for the purposes of describing a presently preferred implementation of the invention.

TABLE 1

Component Part/Model No.

Case 11 Hammond 1591HSBKls

Power switch 12 "on-off" sliding switch, Radio Shack 275-406

Keypad 14 KL0025, Powell Electronics (Irving, TX)

Encoder 42 TX-01, Ming Engineering &

Products, Inc. (City of Industry, CA)

Transmitter 43 315 MHz transmitter TX-77, Ming Engineering & Products, Inc.

RF Receiver 44 Superheterodyne RE-77, Ming Engineering

Decoder 45 RE-01, Ming Engineering

Light-emitting diodes GL538 Infrared LED, Sharp 47 (LI, L2) Electronics

Voltage regulator 60, 64 LM7805

Oscillator 62 LM555

Receiver/decoder GP1U52X, Sharp Electronics module 49

Cl 470 pf

PI 50 KΩ (adjust to obtain 40 KHz at pin 3 of LM555 oscillator)

Rl 1 KΩ R2 Choose value to obtain 100 mA peak current

R3 4.7 KΩ R4 47 Ω Tl 2N3906 Vibrator 51 Pager vibrator 59-5046H03, Motorola Further modifications and alternative embodiments of this invention will be apparent to those skilled in the art in view of this description. Accordingly, this description is to be construed as illustrative only and is for the purpose of teaching those skilled in the art the manner of carrying out the invention. It is to be understood that the forms of the invention herein shown and described are to be taken as the presently preferred embodiments. Various changes may be made in the shape, size, and arrangement of parts. For example, equivalent elements or materials may be substituted for those illustrated and described herein, and certain features of the invention may be utilized independently of the use of other features, all as would be apparent to one skilled in the art after having the benefit of this description of the invention.

Claims

CLAIMS ;

1. A guidance system, comprising:

at least one beacon responsive to a modulated radio-frequency interrogation signal, said beacon comprising an infrared transmitter for emitting an IR response signal;

a transceiver, comprising:

a radio-frequency transmitter for emitting said modulated radio-frequency interrogation signal;

an encoder coupled to said radio-frequency transmitter for selectably modulating said radio-frequency interrogation signal according to a desired destination;

detecting means responsive to an infrared response signal; and

indicating means coupled to said detecting means for indicating reception of said infrared response signal by said detecting means.

2. The guidance system of claim 1, wherein said infrared transmitter comprises an infrared light-emitting diode.

3. The guidance system of claim 1, wherein said detecting means comprises an infrared photodiode.

4. The guidance system of claim 1, wherein said indicating means comprises a vibrator.

5. The guidance system of claim 1, wherein said indicating means comprises a tone generator.

6. The guidance system of claim 1, further comprising a numerical keypad coupled to said encoder for selecting destination codes.

7. The guidance system of claim 1, further comprising a highly directional input port optically coupled to said detecting means.

8. The guidance system of claim 7, wherein said input port comprises a cylindrical lens.

9. A system for guiding the visually impaired toward a destination, comprising:

at least one guide beacon placed at the destination, said beacon comprising:

a radio-frequency receiver/decoder responsive to a coded radio-frequency signal; and

an emitter coupled to said radio-frequency receiver/decoder for emitting an infrared response signal; and

a transceiver, comprising: an input device for entering a destination code;

an encoder coupled to said input device for selectably pulse-modulating a radio- frequency transmitter;

a radio-frequency transmitter coupled to said encoder for transmitting a coded radio- frequency interrogation signal;

a light detector responsive to said infrared response signal; and

indicating means coupled to said light detector for indicating reception of said infrared response signal by said transceiver.

10. The guidance system of claim 9, wherein said input device comprises a numeric keypad.

11. The guidance system of claim 9, wherein said emitter comprises an infrared light-emitting diode.

12. The guidance system of claim 9, wherein said light detector comprises an infrared photodiode.

13. The guidance system of claim 9, wherein said indicating means comprises a vibrator.

14. The guidance system of claim 9, wherein said indicating means comprises a tone generator.

15. The guidance system of claim 9, wherein said guidance system is located within a building, further comprising a directory of destination codes corresponding to various destinations within said building.

16. A method of guiding the visually impaired toward a destination, comprising:

providing at least one guide beacon capable of emitting an infrared response signal in response to reception of a valid radio- frequency interrogation signal;

placing said guide beacon proximate to said destination;

generating a coded radio-frequency interrogation signal;

receiving said coded radio-frequency interrogation signal at said beacon;

processing said received interrogation signal at said beacon to determine if said received interrogation signal is valid for said beacon;

generating an infrared response signal in response to a valid radio-frequency interrogation signal;

detecting an infrared response signal from said beacon; and

indicating reception of said infrared response signal .

17. The method of claim 16, wherein said providing step comprises providing a plurality of guide beacons along a guide path for the target.

18. The method of claim 16, wherein said processing step comprises comparing said radio-frequency interrogation signal with a preset code to determine if said radio- frequency interrogation signal is valid.