JP2008054897A - Detector and its detection method for obstacles near feet - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a small-sized and inconspicuous detector and its detection method for obstacles near the feet of a walker with visual disability, improved in precision of automatic obstacle recognition and reliability of notifying the recognition result to the walker, and capable of forecasting beforehand only the obstacles protruding from flat road surfaces that may cause the walker to tumble down and permitting him to avoid them; in consideration of the fact that the sensors see curbs and other obstacles lying in front of the walker's feet in his advance direction as having apparently the same appearance features, this invention has limited those obstacles seen by the sensor to the ones that must really be recognized by the walker as most probable obstacles to him. <P>SOLUTION: A visually impaired walker carries this detector to detect obstacles existing on a road surface before the walker's feet in his advance direction. The detector is directed forwards and downwards from him. The detector is provided with a plurality of sensors 3, 4 arranged nearly in parallel to each other to measures the distance between the walker and a road surface point he or she is approaching, a decision means to judge whether there is any obstacle to his or her walking from the results of measurement by the sensors, and a notice means 7 to give alarm to the walker from the result of judgment by the decision means. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a foot obstacle detection device and method for detecting an obstacle at a foot in front of a pedestrian such as a visually handicapped person.

  As a representative method for detecting the presence of an object and the distance to the object, there is a method using reflection of electromagnetic waves, sound waves, light, etc. from the object. These are generally called object sensors or distance measuring sensors, and usually consist of a pair of a transmitter and a receiver. Waves emitted from the transmitter are reflected at a certain angle due to the optical and acoustic reflection characteristics of the object surface. The receiving unit calculates the presence of the object and the distance from the sensor to the object based on the intensity, phase, frequency, etc. of the reflected wave.

  Patent Document 1 describes an obstacle detection device for assisting the behavior of a visually impaired person. In this document, as an obstacle while the visually handicapped person is walking, an object in the space where the upper body of the visually handicapped moves, such as a signboard, a street tree, a vehicle handle or mirror, a store display, etc., is assumed. Yes. In actual walking, it is generally an obstacle at the foot that is a problem, but for these, an auxiliary tool called “white cane” is widely spread and well known. The obstacle detection device of Patent Document 1 is intended to detect an obstacle near the upper body including the head as a supplement to the “white cane”.

  According to the interview survey conducted by the present inventor for visually handicapped persons, it was found that the obstacles at the feet could not be detected sufficiently with the white cane, and there were many accidents that caused the feet to hit and fall. A white cane is a simple and convenient device, but due to its structure, it is a point contact detection of collision with an object, and it is trained to swing the cane left and right to detect a wide range. Therefore, the planar detection that a sighted person imagines cannot be performed, and the detection is limited to partial / linear detection, and detection errors are likely to occur. In order to prevent a fall accident, it is necessary to detect an obstacle near the foot without leaking.

The sensor of the method employed in Patent Document 1 determines the presence or absence of an object as an obstacle based on the presence or absence of a reflected wave from the detection range. If there is an object, a reflected wave is generated, and if there is no object, there is no reflected wave. When such a type of sensor is used to detect an object near the road surface, there must be no other objects before and after the object as an obstacle. However, when a projecting obstacle on the road surface is to be detected, if a wave is transmitted from the hand toward the object, a reflected wave is obtained from the projecting obstacle that is the detection target. The reflected wave also returns from the surface. In such a case, the sensor cannot distinguish a reflected wave from an obstacle that is a detection target and a reflected wave from an object other than the detection target (here, a road surface). Therefore, in order to avoid such a phenomenon, it is necessary to install the sensor so as to be horizontal in the vicinity of the road surface, and to secure a space before and behind the object as an obstacle. Patent Documents 2 and 3 describe that a sensor is incorporated into footwear, etc., but sensing is performed under harsh conditions such as impact, water immersion, dirt and dirt, and the sensor is installed to keep the sensor level in the vicinity of the feet. This is very difficult in terms of structure and is not realistic.
JP 2001-8992 A JP 2004-121267 A JP-A-8-95487

  When a single distance measuring sensor is used for one object, the sensor can detect whether an object exists within the detectable distance by the presence or absence of a reflected wave. Further, when an object is present, the distance to the object can be calculated from the intensity, phase, time delay, etc. of the reflected wave. This method is suitable for detecting an object in an empty space as an obstacle. However, when actually trying to detect a walking obstacle of a visually handicapped person, a sensor other than the detection target is placed in front of the sensor. Various objects are mixed. An object such as a flat road surface and a protruding curb is detected as the same object as viewed from the sensor. In this case, the curb that causes the whip falls while walking is an obstacle, but the flat road surface itself is not an obstacle, so when informing the visually impaired about the danger of falling, It is necessary to distinguish between flat road surfaces and obstacles such as curbs.

  Moreover, visually impaired people have a strong tendency to care about the line of sight of sighted people when they go out. It is obliged to carry the white cane when you go out by law, and it has the effect of letting people know the location of the handicapped and alert them to others. There is a strong disgust and shame about drawing. Many of the things that have been proposed and have not been widely used are often required to be attached to conspicuous parts of the head and torso, and they are not “bad” devices that they say. There is a need for a device that can be easily stored.

  The present invention pays attention to the fact that obstacles such as curbs at the foot of the pedestrian in the direction of travel have the same morphological features when viewed through the sensor, and is a recognition object that is really necessary for visually impaired persons. By limiting it as a candidate for an object, it is possible to improve the accuracy of automatic recognition and the reliability of notification, and to predict and avoid only the protruding obstacles on the flat road that cause the whip and fall while walking. It is an object of the present invention to provide a foot obstacle detection device and method that are small and difficult to see. The protruding obstacle referred to here refers to a fixed object that protrudes from a flat road surface with a certain height and does not easily change its position and shape even when it receives a force.

  In order to solve the above problems, the present invention has the following configuration.

  A foot obstacle detecting device that is carried by a pedestrian and that detects a step obstacle in front of the pedestrian, is directed forward and downward of the pedestrian, and measures a distance from the front walking surface of the pedestrian, A plurality of distance measuring sensors arranged substantially parallel to each other, a determination means for determining the presence or absence of a step obstacle in front of the pedestrian based on the measurement results of the plurality of distance measurement sensors, and a determination result of the determination means And a notification means for issuing a warning to the pedestrian.

  A step obstacle detection method for detecting a step obstacle in front of a pedestrian, wherein a plurality of distance measurement sensors arranged substantially parallel to each other are directed downward and forward of the pedestrian, and each distance measurement sensor is connected to the pedestrian. A distance measuring step for measuring a distance from the front walking surface, a determination step for determining the presence or absence of a step obstacle in front of the pedestrian based on the measurement results of the plurality of distance measuring sensors, and a determination in the determination step A step obstacle detection method comprising: a notification step of issuing a warning to the pedestrian based on the result (claim 9).

  The plurality of distance measuring sensors may be arranged in parallel to each other or may be arranged at a slight angle.

  Moreover, it has the following embodiments.

  The plurality of distance measuring sensors may be any one of an infrared distance measuring sensor, an ultrasonic distance measuring sensor, an electromagnetic distance measuring sensor, or a combination thereof.

  There are two distance measuring sensors, and the determining means (step) determines the presence or absence of a step obstacle in front of the pedestrian based on a difference in distance measured by the two distance measuring sensors. 3 and 10). For example, the two distance measuring sensors are a front sensor and a rear sensor, and it is determined that there is a foot obstacle when the measurement distance of the front sensor is shorter than the measurement distance of the rear sensor. The detection range on the walking surface of the front sensor is slightly ahead in the traveling direction than the detection range on the walking surface of the rear sensor.

  Further, the determination means (step) determines that there is a step in front of the pedestrian when at least one of the measurement results of the plurality of distance measuring sensors has a certain value or more, and the notification means ( Process) issues a warning (claims 4 and 11).

  The plurality of distance measuring sensors include transmitters and receivers, and the transmitters and receivers of the distance measuring sensors are parallel to a plane including a direction in which the distance measuring sensors are directed and a horizontal direction. (Claim 5). That is, when viewed from the front so that a plurality of distance measuring sensors are arranged vertically, the transmitter and the receiver are arranged horizontally rather than vertically.

  The foot obstacle detection device has a grip portion, and the grip portion is structured to guide by a tactile sense so that the foot obstacle detection device can be gripped in an optimal direction (Claim 6). For example, a hole for passing a finger or the like is provided in the gripping part, and the step obstacle detection device inevitably becomes a desired orientation when the determined finger is inserted into the determined hole. Or you may provide the convex part which can understand just by touching the direction of a step obstacle detection apparatus.

  Furthermore, it has a fixing means which fixes the said foot obstacle detection apparatus to a pedestrian's body or carrying goods (Claim 7). If it is fixed near the waist of a pedestrian, it can be measured without making it stand out. Moreover, if it fixes to a white cane, it becomes unnecessary to have both a white cane and a step obstacle detection device, and portability improves.

  The informing means issues a warning to the pedestrian by vibration or sound.

  With the configuration of the present invention, it is possible to detect a step obstacle in the traveling direction of a pedestrian such as a visually impaired person with a simple configuration. It becomes possible to efficiently detect a step obstacle in a range where the white cane is difficult to reach. Moreover, since a wide range of step obstacles can be detected compared to a white cane, there are few detection omissions. Since the structure is simple, the device can be miniaturized, can be held in the hand, and does not stand out even when worn on a white cane or body. Furthermore, if the structure of Claim 4 and 11 is employ | adopted, the dangerous level | step difference in front of pedestrians, such as a platform of a station and a downstairs, can be detected.

  In general, a distance measuring sensor includes a transmitter and a receiver, which are arranged in parallel. By arranging the transmitter and the receiver as in claim 5, the range in which the distance measuring sensor can measure the distance on the walking surface spreads in a direction perpendicular to the direction of travel of the pedestrian. Is less. In addition, since the range in which the pedestrian can travel is narrowed, detection errors of the step obstacles are reduced and the detection accuracy is increased.

  The foot obstacle detection device of the present invention has to place the plurality of distance measuring sensors in a predetermined state. However, when the user is a visually handicapped person, the plurality of distance measuring sensors are arranged in a desired position / direction. It is difficult to hold the step obstacle detection device in the hand. By adopting the gripping part as in claim 6, it is possible to arrange each distance measuring sensor in a desired arrangement and orientation without making a mistake even by a visually handicapped person or the like by simply grasping the gripping part.

  An embodiment of the present invention will be described. FIG. 1 is a schematic diagram of a step obstacle detection apparatus according to an embodiment of the present invention. FIG. 1 is a front view, a side view, and a bottom view.

  Two distance measuring sensors (the front sensor 3 and the rear sensor 4) are fixed to the lower part of the casing 8 that can be gripped by the palm. The case is about the size of a palm and can be stored in a pocket when not needed. The user passes four fingers through the center hole, and holds the part in which the vibration motor 7 is built in a manner of grasping with a palm. If this device is gripped in the wrong direction, the positions of the front and rear ranging sensors will be reversed, and accurate measurement may not be possible. By providing a convex portion or the like, it is possible to prevent the visually handicapped person from making a mistake in the grip direction. During walking, the sensor mounting surface is held up in the direction of the lower road surface in the direction of travel (the direction in which the arm is swung). The two distance measuring sensors are operated alternately to avoid interference, and each time the distance to the reflecting surface is measured. Each range sensor is equipped with a transmitter and a receiver, but by placing the transmitter and receiver of each range sensor sideways as shown in the figure, each range sensor can measure the distance on the walking surface. Since the possible range extends in a direction orthogonal to the direction of travel of the pedestrian, detection omissions are reduced. In addition, since the range in which the pedestrian can travel is narrowed, detection errors of the step obstacles are reduced and the detection accuracy is increased. The presence or absence of a step obstacle is judged by a judgment means not shown, and the vibration motor is stopped when the ground is flat without any obstacle, but the vibration motor is driven when the judgment means judges that there is a step obstacle. In addition, it is possible to recognize the presence of an obstacle by feeling vibration with a palm through the housing. Instead of the vibration motor, a method of notifying the user by sound generation using an electronic buzzer or the like may be used. Further, instead of the infrared distance measuring sensor, a distance measuring sensor using ultrasonic waves or electromagnetic waves may be used.

  Hereinafter, the detection principle of the step obstacle in the present embodiment will be described with reference to FIGS.

  FIG. 2 is a diagram illustrating a detection state on a flat road surface. Two distance measuring sensors using infrared reflection are juxtaposed along the traveling direction 1 of walking, and both transmission / reception surfaces are held in the direction of the road surface 9 obliquely below the traveling direction which is the detection direction 2. Here, a sensor whose detection range is the front side of the traveling direction is a front sensor 3, and a sensor whose detection range is the rear side is a rear sensor 4. Both sensors alternately measure the distance to the road surface 9, which is a reflective surface, and the distances detected by each sensor are 3A and 4A. The sensor is fixed so that the center of the detection range of each sensor is a constant distance 5 in the traveling direction on the road surface. In the case of a flat road surface 9 where no object is present, the relationship between the detection distances of both sensors is 3A> 4A.

  FIG. 3 is a diagram illustrating an obstacle detection state. When approaching an obstacle 60 such as a curb, the obstacle 60 first enters the detection range of the front sensor 3. At this time, the distance 3A detected by the front sensor 3 is shortened, and the relationship between the detection distances of both sensors is reversed as 3A <4A. Note that the magnitude of the difference between 3A and 4A depends on the protrusion height 60A of the obstacle 60.

  FIG. 4 is a diagram illustrating a detection state of a vertically long obstacle. When the height 60A of the obstacle is large and the depth 60B is small, the detection area of both sensors exceeds the state of FIG. 2 depending on the measurement interval of the distance measuring sensor and how to hold the device. Sometimes. In this case, the relationship between the detection distances of the two sensors becomes 3A> 4A, and if attention is paid only to the magnitude relationship between the values, there is a possibility that the situation is recognized as being the same as a flat road surface without an obstacle. However, in this case, since the absolute value of the difference becomes extremely larger than that on a flat road surface, it can be inferred that some object exists in the vicinity if attention is paid to the magnitude of the absolute value. .

  FIG. 5 is a diagram illustrating a detection state in a place where there is a head in front. In places where there is a drop at the end of the walking route, such as a platform of a station or a descending staircase, the magnitude relationship and difference of the detection distance are characteristic as shown in the figure. When reaching the end portion 93 of the flat road surface where the head appears in the traveling direction, the detection distance 3A of the front sensor 3 first exceeds the maximum detection distance of the sensor (FIG. 5A). At this time, the notifying means issues a warning, but at the time of further forward due to inertia, the rear sensor 4 exceeds the maximum detection distance in addition to the front sensor 3 (FIG. 5B). The distance 95 to the end when the two sensors exceed the maximum detection distance is the limit stop distance at which the fall can be prevented. The warning needs to be issued when this distance 95 can be secured sufficiently.

  FIG. 6 is an explanatory diagram when the detection range is widened. Although FIGS. 2-5 demonstrated the case where the detection direction of the front sensor 3 and the rear sensor 4 was parallel, you may expand the detection direction of the front sensor 3 and the rear sensor 4 a little wider than parallel, and may make a wide angle. When the user is walking at a certain speed, if the detection interval 5 of both sensors is short, the obstacle 60 will immediately enter the detection range of both sensors, and accurate detection cannot be guaranteed. In order to avoid such a phenomenon, the problem in the normal walking speed range can be avoided by fixing both sensors so that the tip of the detection direction axis is widened and increasing the detection interval 5. In this case, only the direction of both sensors is changed, and the fixed interval itself does not need to be enlarged, so that the apparatus itself does not increase.

As mentioned above, although one example of the embodiment of the present invention has been described based on the drawings, the present invention is not limited to the illustrated example, and various modifications are possible within the scope of the technical idea described in the claims. Needless to say.

It is the schematic of the step obstacle detection apparatus which concerns on embodiment of this invention. It is a figure which shows the detection condition in a flat road surface. It is a figure which shows the detection condition of an obstruction. It is a figure which shows the detection condition of a vertically long obstacle. It is a figure which shows the detection condition in the place where there is a head ahead. It is explanatory drawing at the time of widening a detection range.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Traveling direction 2 Detection direction 3 Front sensor 3A Detection distance by front sensor 4 Rear sensor 4A Detection distance by rear sensor 5 Distance between detection centers of each sensor 7 Vibration motor 8 Housing 9 Road surface 60 Obstacle 60A Obstacle height 60B Depth of obstacle 93 Head part 95 Fall prevention limit stop distance

Claims (11)

A foot obstacle detection device that is carried by a pedestrian and detects a foot obstacle in front of the pedestrian,
A plurality of distance measuring sensors that are directed in front of the pedestrian and that measure the distance from the front walking surface of the pedestrian, arranged substantially parallel to each other;
Based on the measurement results of the plurality of distance measuring sensors, determination means for determining the presence or absence of a step obstacle in front of the pedestrian,
Based on the determination result of the determination means, notification means for issuing a warning to the pedestrian,
Foot obstacle detection device having   2. The step obstacle according to claim 1, wherein the plurality of distance measuring sensors are any one of an infrared distance measuring sensor, an ultrasonic distance measuring sensor, an electromagnetic wave distance measuring sensor, or a combination thereof. Detection device. There are two distance measuring sensors,
3. The step obstacle detection according to claim 1, wherein the determination unit determines the presence or absence of a step obstacle ahead of the pedestrian based on a difference between distances measured by two distance measuring sensors. apparatus.   Further, the determination means determines that there is a step in front of the pedestrian when at least one of the measurement results of the plurality of distance measuring sensors has a certain value or more, and the notification means issues a warning. The foot obstacle detecting device according to any one of claims 1 to 3.   The plurality of distance measuring sensors include transmitters and receivers, and the transmitters and receivers of the distance measuring sensors are parallel to a plane including a direction in which the distance measuring sensors are directed and a horizontal direction. The foot obstacle detecting device according to any one of claims 1 to 4, wherein the step obstacle detecting device is disposed.   2. The foot obstacle detection device includes a grip portion, and the grip portion is structured to guide by a tactile sense so that the foot obstacle detection device can be gripped in an optimum direction. The step obstacle detection device according to any one of 5 to 5.   The foot obstacle detecting device according to any one of claims 1 to 6, further comprising fixing means for fixing the foot obstacle detecting device to a pedestrian's body or a carry-on item.   The foot obstacle detection device according to any one of claims 1 to 7, wherein the notification unit issues a warning to the pedestrian by vibration or sound. A step obstacle detection method for detecting a step obstacle in front of a pedestrian,
A distance measuring step in which a plurality of distance measuring sensors arranged substantially parallel to each other are directed downward and forward of the pedestrian, and each distance measuring sensor measures a distance from the walking surface in front of the pedestrian,
A determination step of determining the presence or absence of a step obstacle in front of the pedestrian based on the measurement results of the plurality of distance measuring sensors;
Based on the determination result of the determination step, a notification step for issuing a warning to the pedestrian,
A step obstacle detection method comprising: There are two distance measuring sensors,
10. The step obstacle detection method according to claim 9, wherein in the determination step, presence / absence of a step obstacle in front of the pedestrian is determined based on a difference between distances measured by two distance measuring sensors.   Further, the determination step determines that there is a step in front of the pedestrian and issues a warning in the notification step when at least one of the measurement results of the plurality of distance measuring sensors has a certain value or more. The step obstacle detection method according to claim 9 or 10.

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