JP7367322B2 - Object position detection sensor - Google Patents

Description

The present invention relates to an object position detection sensor.

Patent Document 1 describes an obstacle detection device (corresponding to the object position detection sensor of the present application). This obstacle detection device first obtains envelope waves of reflected waves received by a plurality of receivers (an example of an ultrasonic sensor), determines the apex time of each, and obtains an estimated rise value. Then, a candidate combination of envelope waves is selected based on the relationship between the peak times of each envelope wave. Furthermore, the position of a candidate obstacle (corresponding to the object of the present invention) is calculated based on the estimated rise value corresponding to the calculated combination.

Japanese Patent Application Publication No. 2007-322225

As described above, when an estimated rise value is obtained from the envelope of the reflected wave received by the ultrasonic sensor, the error in the obtained estimated rise value tends to be large. Therefore, there was a problem that the detection position accuracy of the target object deteriorated. When detecting the position of an object using the phase difference of reflected waves received by multiple ultrasonic sensors instead of the envelope, due to the size (diameter) of the ultrasonic sensors, the phase difference Therefore, it is difficult to perform highly accurate detection as it is. Therefore, it is desired to provide an object position detection sensor that can detect the object position with high accuracy.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an object position detection sensor that can detect the object position with high accuracy.

The characteristic structure of the object position detection sensor according to the present invention for achieving the above object is as follows: the plurality of ultrasonic sensors in the sensor group, comprising: a detection unit that detects a position of the object based on a direction of the object with respect to the ultrasonic sensor and a distance from the ultrasonic sensor to the object; have their wave-receiving surfaces facing the same direction and are arranged in a straight line, and if any two ultrasonic sensors in the sensor group are defined as one set, then one set The first inter-sensor distance, which is the distance between the two ultrasonic sensors, exceeds the second inter-sensor distance, which is the distance between the other two ultrasonic sensors, and the detection unit The distance is calculated based on the time from when the ultrasonic sensor transmits the ultrasonic wave to when the ultrasonic sensor receives the ultrasonic wave, and the distance is calculated based on the time from when the ultrasonic sensor transmits the ultrasonic wave to when the ultrasonic sensor receives the ultrasonic wave. It is set to detect the angle θ of deflection in the direction in which the ultrasonic waves are deflected, and the phase difference between the reflected waves received by each of the ultrasonic sensors between the two ultrasonic sensors of the certain set and the other An inter-group phase difference, which is a difference between a set of two ultrasonic sensors and a phase difference of the reflected waves received by each of the ultrasonic sensors, the first inter-sensor distance and the second inter-sensor distance; The point is that the direction is calculated by finding the angle θ based on equation (1) that is satisfied by the difference α, the wavelength λ of the reflected wave, and the angle θ.
α・sinθ=λ・(intergroup phase difference/360°) Formula (1)

According to the above configuration, the first inter-sensor distance in the sensor group exceeds the second inter-sensor distance. As a result, the difference obtained by subtracting the second inter-sensor distance from the first inter-sensor distance (hereinafter referred to as difference α) and the phase difference of the reflected waves between one set of ultrasonic sensors and the other set of ultrasonic sensors are calculated. Based on the difference in phase difference (hereinafter referred to as inter-set phase difference) obtained by subtracting the phase difference of the reflected waves between the ultrasonic sensors, the waves reflected from the object are aligned along the direction in which the wave receiving surface is directed. The angle of incidence on the ultrasonic sensor on a virtual plane along the direction and the direction in which the plurality of ultrasonic sensors are arranged (hereinafter referred to as the arrangement direction) can be detected as the direction of the object. By detecting the direction of the object based on the phase difference in this manner, it is possible to improve the detection position accuracy.

Note that the distance between the object position detection sensor and the object is determined by the time from when the ultrasonic sensor transmits ultrasonic waves and when the reflected waves are received, the time from when the ultrasonic waves are transmitted until the reflected waves are received, and the speed of sound. The distance to the obstacle can be determined by the so-called time-of-flight (TOF) method, which measures the distance to the obstacle based on the following. Therefore, according to the above configuration, the position of the object can be detected based on the direction of the object and the distance to the object.

Below, regarding the incident angle of the reflected wave on the virtual plane, the angle of deflection from the direction along the direction in which the wave receiving surface is directed to the direction in which the plurality of ultrasonic sensors are arranged (hereinafter referred to as the arrangement direction) is expressed as follows: It may be written as angle θ.

A further characteristic configuration of the object position detection sensor according to the present invention is that when the detection range of the angle θ is set from the angle θmax to the angle -θmax with reference to the direction in which the wave receiving surface is directed, The relationship between the angle θmax, the wavelength λ of the reflected wave, and the difference α satisfies the following formula ( 2 ).
λ≧2・α・sin(θmax) Formula ( 2 )

If the absolute value of the inter-group phase difference exceeds 180°, the angle θ cannot be determined based only on the difference α and the inter-group phase difference. However, according to the above configuration, the absolute value of the inter-group phase difference is 180°. The angle θ can be determined based only on the difference α and the inter-group phase difference.

A further characteristic configuration of the object position detection sensor according to the present invention is that the sensor group includes a first ultrasonic sensor, a second ultrasonic sensor, and a third ultrasonic sensor, and the first ultrasonic sensor The sonic sensor and the second ultrasonic sensor constitute one set, and the second ultrasonic sensor and the third ultrasonic sensor constitute the other set.

According to the above configuration, the angle θ can be accurately determined using at most three sensors: the first ultrasonic sensor, the second ultrasonic sensor, and the third ultrasonic sensor.

A further feature of the object position detection sensor according to the present invention is that the centers of gravity of the wave receiving surfaces of the plurality of ultrasonic sensors in the sensor group are arranged on a straight line.

By arranging the center of gravity of each wave receiving surface of the ultrasonic sensor on a straight line as in the above configuration, the accuracy in determining the angle θ is improved.

A further characteristic configuration of the object position detection sensor according to the present invention is that the sensor group includes a first sensor group in which the three or more ultrasonic sensors are arranged along the first direction; a second sensor group in which the three or more ultrasonic sensors are arranged along a second intersecting direction;
The detection unit detects the position of the object in the first direction and the position of the object in the second direction.

According to the above configuration, for the reflected wave from the target object, the angle of incidence on the ultrasonic sensor of the first sensor group in the direction along the direction in which the wave receiving surface is directed and the first direction is It can be detected as the position of an object. In addition, regarding the reflected wave from the target object, the angle of incidence on the ultrasonic sensor of the second sensor group in the direction along the direction in which the wave receiving surface is directed and the second direction is defined as the position of the target object. can be detected. Thereby, the position of the object in the first direction and the second direction can be detected.

It is possible to provide an object position detection sensor with high detection position accuracy of the object.

Diagram showing the overall configuration of the detector Diagram showing the arrangement of ultrasonic sensors in the sensor body Diagram explaining reception of reflected waves and position detection of obstacle T in the first sensor group

An object position detection sensor according to an embodiment of the present invention will be described based on FIGS. 1 to 3.

[About the detector configuration]
FIG. 1 shows the overall configuration of a detector 1 for an obstacle T (an example of an object) as an example of an object position detection sensor. The detector 1 is used, for example, as an obstacle detector for a vehicle (not shown). The detector 1 includes a sensor body 2 in which ultrasonic sensors 11, 12, 13, 14, and 15 (an example of a plurality of ultrasonic sensors, hereinafter referred to as ultrasonic sensors 11 to 15) are disposed, and a control unit. 8 (an example of a detection section), and a control main body 9 having a wave transmitting/receiving circuit (not shown) that transmits and receives a predetermined electric signal. When referring to any one of the ultrasonic sensors 11 to 15, it is simply written as a sensor.

The ultrasonic sensors 11 to 15 each include an ultrasonic transducer (not shown) and an ultrasonic wave W emitted by the ultrasonic transducer to the outside, and an external ultrasonic wave (for example, a reflected wave R of the ultrasonic wave W). It includes a wave transmitting/receiving surface S (an example of a wave receiving surface) of a diaphragm (not shown) that receives the waves. The ultrasonic sensors 11 to 15 externally transmit ultrasonic waves W having a predetermined wavelength λ (predetermined frequency) corresponding to the electrical signals transmitted from the control main body 9, and generate electrical signals corresponding to the received reflected waves R, etc. is transmitted to the control main body 9. The transmitting/receiving wave surface S has a circular shape in this embodiment. The ultrasonic sensors 11 to 15 of this embodiment are of the same standard.

The ultrasonic sensors 11 to 15 have, for example, a cylindrical main body. The diameter of the main body is, for example, 12 mm.

The predetermined frequency of the ultrasonic waves W emitted by the ultrasonic sensors 11 to 15 is, for example, 58 kHz. In this case, assuming that the sound speed is 340 m/sec, the wavelength λ of the ultrasonic wave W is approximately 5.86 mm. In the following, the wavelength λ of the ultrasonic waves W emitted by the ultrasonic sensors 11 to 15 will be simply referred to as wavelength λ.

The sensor body 2 is a unit in which ultrasonic sensors 11 to 15 are fixed to a substrate or the like. In the sensor body 2, the ultrasonic sensors 11 to 15 are arranged so that their respective wave transmitting and receiving surfaces S are oriented in the same direction. In the sensor body 2, ultrasonic sensors 11 to 15 are arranged at predetermined intervals.

FIG. 2 is a plan view of the ultrasonic sensors 11 to 15 of the sensor body 2 viewed from the side toward which the wave transmitting/receiving surface S faces, and shows the arrangement of the ultrasonic sensors 11 to 15 in the sensor body 2. In this embodiment, the ultrasonic sensors 11 to 15 are fixed to a substrate or the like while being covered with a vibration damping material 10 such as vibration isolating rubber. Note that the damping material 10 is not an essential member.

Ultrasonic sensors 11, 12, and 13 are arranged in the sensor body 2 along the first direction. In this embodiment, the first direction is, for example, the horizontal direction. Hereinafter, the group of ultrasonic sensors 11, 12, and 13 (each an example of a first ultrasonic sensor, a second ultrasonic sensor, and a third ultrasonic sensor) will be referred to as a first sensor group G1.

Further, in the sensor body 2, ultrasonic sensors 14, 12, and 15 (respectively, another example of a first ultrasonic sensor, a second ultrasonic sensor, and a third ultrasonic sensor) are arranged in a second direction. It is located along. In this embodiment, the second direction is, for example, the vertical direction. Below, the group of ultrasonic sensors 14, 12, and 15 will be referred to as a second sensor group G2.

In FIG. 2, a virtual line A is a straight line along the first direction. The centers (centers of gravity) of the wave transmitting and receiving surfaces S of the ultrasonic sensors 11, 12, and 13 overlap with the virtual line A. The distance between the ultrasonic sensors 11 and 12 (first inter-sensor distance) is set to distance m, and the distance between ultrasonic sensors 12 and 13 (second inter-sensor distance) is set to distance n. There is. The distance m is greater than the distance n, and the difference therebetween is the difference α. The distance m is, for example, 23.6 mm, and the distance n is, for example, 21.0 mm. In this case, the difference α is 2.6 mm.

In FIG. 2, a virtual line B is a straight line along the second direction. The centers (centers of gravity) of the wave transmitting/receiving surfaces S of the ultrasonic sensors 14, 12, and 15 overlap with the virtual line B. The distance between the ultrasonic sensors 14 and 12 is set to a distance j, and the distance between the ultrasonic sensors 12 and 15 is set to a distance k. In this embodiment, distance j is equal to distance m. Further, in this embodiment, the distance k is equal to the distance n.

The sensor body 2 is configured to generate ultrasonic waves W emitted by at least one of the ultrasonic sensors 11 to 15 (in this embodiment, the ultrasonic sensor 12 as an example) is reflected by an obstacle T (an example of a target object). The reflected wave R is received by all the ultrasonic sensors 11 to 15. When the ultrasonic sensors 11 to 15 receive the reflected wave R, they transmit electrical signals corresponding to the reflected wave R to the control main body 9 (see FIG. 1). In this embodiment, as an example, all the ultrasonic sensors 11 to 15 are configured to receive the reflected wave R of the ultrasonic wave W emitted by the ultrasonic sensor 12.

Since the ultrasonic sensors 11 to 15 are arranged at predetermined intervals, the distances from the obstacle T to each of the ultrasonic sensors 11 to 15 are different. Therefore, the ultrasonic sensors 11 to 15 each receive the reflected wave R at different timings. Specifically, the closer the sensor is to the obstacle T, the earlier the reflected wave R is received. On the other hand, the farther the sensor is from the obstacle T, the later the reflected wave R is received. Therefore, the reflected waves R received by the ultrasonic sensors 11 to 15 have a phase shift corresponding to the distance between the obstacle T and the ultrasonic sensors 11 to 15.

Based on a command from the control unit 8, the control body 9 uses a wave transmitting/receiving circuit to generate an electric signal for causing a sensor (for example, the ultrasonic sensor 12) to emit a predetermined ultrasonic wave W, and transmits it to the sensor. . The control main body 9 inputs the electric signal output from the sensor upon reception of the reflected wave R to the wave transmitting/receiving circuit, and the control unit 8 acquires predetermined information from the electric signal. The control unit 8 determines the phase shifts of the reflected waves R received by the ultrasonic sensors 11 to 15, and detects the position of the obstacle T based on these phase shifts.

[About detection in the first sensor group]
Based on FIG. 3, reception of the reflected wave R in the first sensor group G1 and detection of the position of the obstacle T will be explained. FIG. 3 shows the ultrasonic sensors 11, 12, 13, the imaginary line A, the axis P of the transmitting/receiving wave surface S along the direction in which the transmitting/receiving wave surface S of the ultrasonic sensors 11, 12, 13 faces, and the ultrasonic sensors 11, 12. , 13, a propagation path r, which is a locus along which a reflected wave R of a predetermined wavelength propagates, and an obstacle T are illustrated. In this description, for the sake of simplicity, a case will be illustrated in which at least a portion of the obstacle T overlaps a plane including the virtual line A and the axis P. If the obstacle T does not overlap with the plane containing the virtual line A and the axis P, then for each of the obstacle T, the propagation path r, and the reflected wave R of the ultrasonic wave W incident on the sensor at the propagation path r, It may be based on the respective projected images obtained by orthogonally projecting these onto the plane.

In FIG. 3, the angle θ is the intersection angle between the propagation path r and the axis P. That is, the obstacle T is located at a position deviated from the axis P by an angle θ in the direction along the virtual line A when viewed from the first sensor group G1.

In FIG. 3, for a pair of ultrasonic sensors 11 and 12 (one example of a certain pair), the difference between the distance of the ultrasonic sensor 11 to the obstacle T and the distance of the ultrasonic sensor 12 to the obstacle T is shown. is defined as the distance difference d12. Note that the distance difference d12 is equal to m·sinθ.

In FIG. 3, for a pair of ultrasonic sensors 12 and 13 (an example of another pair), the distance of the ultrasonic sensor 12 to the obstacle T and the distance of the ultrasonic sensor 13 to the obstacle T are shown. The difference is defined as a distance difference d23. Note that the distance difference d23 is equal to n·sin θ.

The distance difference d12 is equal to m・sinθ, and the distance difference d23 is equal to n・sinθ. Therefore, if the difference between the distance difference d12 and the distance difference d23 is defined as the relative distance difference, the difference between the distance m and the distance n is the difference α Therefore, the relative distance difference is equal to α·sinθ.

In the detector 1, when the detection range of the angle θ in the detector 1 is set from the angle θmax to the angle -θmax, the relationship between the wavelength λ, the angle θmax, and the difference α satisfies the following formula (1). is set to .
λ≧2・α・sin(θmax) Formula (1)

That is, the detector 1 is set so that the maximum absolute value of the relative distance difference is 1/2λ or less in the detection range of the angle θ in the detector 1.

In the detector 1 in this embodiment, the angle θmax is set to 90°, as an example. That is, the detection range of the angle θ in the detector 1 is set from 90° to −90°, and the value of sin(θmax) is 1. As mentioned above, the difference α in this embodiment is 2.6 mm and the wavelength λ is about 5.86 mm, so the difference α is less than 1/2λ, that is, the wavelength λ is more than twice the difference α, and the above formula (1) is satisfied.

The phase difference between the phase of the reflected wave R received by the ultrasonic sensor 11 and the phase of the reflected wave R received by the ultrasonic sensor 12 (from -90° to 90°) is defined as the first phase difference below. do. In addition, the phase difference (however, from -90° to 90°) between the phase of the reflected wave R received by the ultrasonic sensor 12 and the phase of the reflected wave R received by the ultrasonic sensor 13 is hereinafter referred to as a second phase difference. It is defined as Furthermore, the difference between the first phase difference and the second phase difference is defined as an inter-group phase difference. In this case, as mentioned above, detector 1 is set so that the maximum absolute value of the relative distance difference is 1/2λ or less. (The absolute value of the inter-group phase difference is 180° or less).

When the inter-group phase difference is determined, the relative distance difference is obtained as λ·(inter-group phase difference/360°). Since the relative distance difference is equal to α·sin θ and the difference α is known, the angle θ can be determined from the difference α and the relative distance difference.

The control unit 8 calculates the relative distance difference from the known difference α and the phase of the reflected waves R received by the ultrasonic sensors 11, 12, and 13, and determines the position of the obstacle T based on the difference α and the relative distance difference. , on a plane overlapping the axis P and the imaginary line A, as seen from the first sensor group G1, the angle θ at which the obstacle T curves from the axis P in the direction along the imaginary line A is determined.

[About detection in the second sensor group]
Detection in the second sensor group G2 is performed in the same way as the detection in the first sensor group G1. The second sensor group G2 is similar to the case where the ultrasonic sensors 11, 12, and 13 in the first sensor group G1 are replaced with the ultrasonic sensors 14, 12, and 15 in the second sensor group G2.

The control unit 8 calculates the relative distance difference in the second sensor group G2 from the known difference α in the second sensor group G2 and the phase of the reflected waves R received by the ultrasonic sensors 14, 12, and 15, and calculates the relative distance difference in the second sensor group G2. As in the case of group G1, the position of the obstacle T is such that the obstacle T moves from the axis P to the imaginary line B when viewed from the second sensor group G2 on a plane that overlaps the axis P and the imaginary line B. Find the angle of warpage in the direction along.

In this way, the control unit 8 determines the position of the obstacle T in the space defined by the three axes of the axis P, the virtual line A, and the virtual line B.

As described above, it is possible to provide an object position detection sensor with high detection position accuracy. In other words, even when the diameter of the ultrasonic sensors is large and the distance between the sensors cannot be made small, the detector 1 can detect the angle θ by using the phase difference between the sets, and it is possible to detect the angle θ by using the phase difference between the sets. You can get the same effect as if you placed the In addition, since the detector 1 detects the angle θ based on the phase difference, it can detect obstacles with higher precision than a device that detects the position of the obstacle T using an envelope, such as that described in Patent Document 1. The position of the object T can be detected.

[Another embodiment]
(1) In the above embodiment, the case where the ultrasonic sensors 11 to 15 are disposed in the sensor body 2 has been described as an example. However, the sensor body 2 only needs to include at least the ultrasonic sensors 11, 12, and 13 (first sensor group G1) or the ultrasonic sensors 14, 12, and 15 (second sensor group G2).

(2) In the above embodiment, the first sensor group G1 is a group of ultrasonic sensors 11, 12, and 13. However, the first sensor group G1 may include four or more sensors. Good too. The same applies to the second sensor group G2.

(3) In the above embodiment, a case has been described in which the centers (centers of gravity) of the wave transmitting/receiving surfaces S of the sensors of the first sensor group G1 and the second sensor group G2 overlap with the virtual line A and the virtual line B. However, it is sufficient that the wave transmitting/receiving surfaces S of the sensors of the first sensor group G1 and the second sensor group G2 are arranged in a straight line so as to overlap at least the virtual lines A and B.

(4) In the above embodiment, the case in which the angle θmax is 90° has been specifically explained. Can take a value.

(5) In the above embodiment, a case has been described in which the distance m is larger than the distance n, the distance j is equal to the distance m, and the distance k is equal to the distance n. However, distances j and k are not limited to being equal to distances m and n, respectively. It is sufficient that the distance j is greater than the distance k.

Note that the configurations disclosed in the above embodiments (including other embodiments, the same applies hereinafter) can be applied in combination with the configurations disclosed in other embodiments as long as there is no contradiction, and The embodiments disclosed in this specification are illustrative, and the embodiments of the present invention are not limited thereto, and can be modified as appropriate without departing from the purpose of the present invention.

The present invention can be applied to an object position detection sensor.

1: Detector (object position detection sensor)
2: Sensor body 8: Control section (detection section)
11: Ultrasonic sensor 12: Ultrasonic sensor 13: Ultrasonic sensor 14: Ultrasonic sensor 15: Ultrasonic sensor A: Virtual line (straight line)
B: Virtual line (straight line)
G1: First sensor group G2: Second sensor group P: Axis center (direction in which the wave receiving surface is directed)
R: Reflected wave (ultrasonic wave)
S: Transmitting and receiving wave surface (receiving wave surface)
T: Obstacle (object)
W: Ultrasonic wave j: Distance (distance between sensors)
k: Distance (distance between sensors)
m: Distance (distance between sensors)
n: Distance (distance between sensors)
α: Difference θ: Angle θmax: Angle

Claims (5)

a sensor group including three or more ultrasonic sensors that receive reflected waves of ultrasonic waves reflected from a target object;
a detection unit that detects the position of the object based on the direction of the object with respect to the ultrasonic sensor and the distance from the ultrasonic sensor to the object,
The plurality of ultrasonic sensors in the sensor group each have their wave receiving surfaces directed in the same direction and are arranged in a straight line,
When any two ultrasonic sensors in the sensor group are defined as one set, the first inter-sensor distance, which is the distance between the two ultrasonic sensors in one set, is the distance between the two ultrasonic sensors in the other set. exceeding a second inter-sensor distance that is a distance between two of the ultrasonic sensors;
The detection unit includes:
Calculating the distance based on the time from when the ultrasonic sensor transmits the ultrasonic wave until it receives the ultrasonic wave,
It is set to detect, as the direction of the target object, an angle θ that bends in the direction in which the wave receiving surface is arranged in a straight line with reference to the direction in which the wave receiving surface is directed;
The phase difference between the reflected waves received by each of the ultrasonic sensors between the two ultrasonic sensors of the certain set and the reflected waves received by the ultrasonic sensors between the two ultrasonic sensors of the other set. The expression (( 1) An object position detection sensor that calculates the direction by determining the angle θ.
α・sinθ=λ・(intergroup phase difference/360°) Formula (1) When the detection range of the angle θ in the detection unit is set from angle θmax to angle -θmax with reference to the direction in which the wave receiving surface is directed,
The object position detection sensor according to claim 1, wherein a relationship among the angle θmax, the wavelength λ of the reflected wave, and the difference α satisfies the following formula (2).
λ≧2・α・sin(θmax) Formula (2) The sensor group consists of a first ultrasonic sensor, a second ultrasonic sensor, and a third ultrasonic sensor,
The first ultrasonic sensor and the second ultrasonic sensor constitute the certain set, and the second ultrasonic sensor and the third ultrasonic sensor constitute the other set. The object position detection sensor according to claim 1 or 2. The object position detection sensor according to any one of claims 1 to 3, wherein the center of gravity of the wave receiving surface of each of the plurality of ultrasonic sensors in the sensor group is arranged on a straight line. The sensor group includes a first sensor group in which the three or more ultrasonic sensors are arranged along a first direction, and a first sensor group in which the three or more ultrasonic sensors are arranged in a second direction intersecting the first direction. a second sensor group disposed;
The object position detection sensor according to any one of claims 1 to 4, wherein the detection unit detects a position of the object in the first direction and a position of the object in the second direction.

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