JPH04344487A - Distance measuring apparatus - Google Patents

Abstract

PURPOSE:To provide a distance measuring apparatus capable of precisely judging a subject for detection and outputting information properly in accordance with the distance to the subject. CONSTITUTION:A distance measuring apparatus is comprised of an antenna 9 which emits electromagnetic wave toward a subject, a scanner 11 which scans plural areas of the subject by changing the direction of emission of the electromagnetic wave, a distance measuring circuit 15 which receives the electromagnetic wave reflected back at the plural areas of the subject, a judging circuit 19 which determines whether or not the subject is a vehicle according to the distribution of areas whose measured values are the same, and an informing circuit 23 which if the subject is judged to be a vehicle outputs information in accordance with the measured value of the distance to the vehicle.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a distance measuring device, and more particularly to a distance measuring device that outputs notification information in accordance with a measured distance to a vehicle other than the own vehicle.

0002

2. Description of the Related Art In recent years, various distance measuring devices have been developed that use appropriate detectors to accurately detect, for example, the distance to a vehicle traveling in front of one's own vehicle.

As such a conventional device, one shown in FIG. 10 is known. As shown in FIG. 10, when an oscillation output from an oscillator 101 using a Gunn oscillator or the like is applied to a pulse switch 103, the pulse switch 10
3 outputs a pulse-like signal in synchronization with the trigger signal from the trigger circuit 105. As a result, pulsed electromagnetic waves are emitted from the antenna 107 toward an object 109 such as a vehicle. The electromagnetic waves reflected by this object 109 are input to a detector 113 via an antenna 111. Detector 1
The signal detected at 13 is applied to a clock generation circuit 115. This clock generation circuit 115 generates a clock that serves as a reference for time measurement, and measures the time required for the emitted electromagnetic wave to be reflected by the object 109 and returned. This measurement information is stored in a distance measuring microcomputer (hereinafter simply referred to as a microcomputer) 11.
7, and the distance to the object 109 is calculated. Here, if the time required for the emitted electromagnetic wave to reflect from the object 109 and return is Δt, and the speed of the electromagnetic wave is C, then the distance R to the object 109 is as follows (1
) is calculated using the formula.

[0004] R=C×Δt/2...

(1) If the value of the distance R calculated by the above formula (1) is less than or equal to a predetermined value, the situation determination circuit 119 determines that the distance to the vehicle in front, that is, the inter-vehicle distance is less than or equal to a predetermined value. Determine. Thereby, the notification circuit 121 notifies the driver that the inter-vehicle distance is less than a predetermined distance by lighting a lamp or sounding a buzzer or the like.

[0005]

[Problems to be Solved by the Invention] As described above, when measuring the inter-vehicle distance, the conventional device emits electromagnetic waves in a fixed direction toward the vehicle 123 in front, as shown in FIG. , Therefore, if the positional relationship between the own vehicle 125 and the vehicle 123 located in front is constant, that is, the position of the vehicle 123 is in the direction in which electromagnetic waves are emitted, the portion where the electromagnetic waves are irradiated to the vehicle 123 located in front of the host vehicle 125 is constant. Only one point was targeted for detection.

Therefore, as shown in FIG.
If the distance between the vehicle 123 and the vehicle 123 in front is sufficient, the guardrail or support 129 installed on the side strip of the road 127 is detected as an object for distance detection while passing a curve. There were cases where it was put away.

The present invention has been made in view of the above problems, and provides a distance measuring device that can accurately determine an object to be detected and output notification information appropriately according to the distance to the object. The purpose is to provide.

[0008]

[Means for Solving the Problems] As shown in FIG. 1, the means according to the present invention to achieve the above object includes an emitting means 2 for emitting electromagnetic waves toward an object to be measured, and a means for emitting electromagnetic waves from the emitting means 2. A scanning means 4 for sequentially changing the direction of emitted electromagnetic waves to scan a plurality of areas set on the object, and receiving the electromagnetic waves reflected by each area of the object scanned by the scanning means 4 A measuring means 6 that measures the distance from the electromagnetic wave to the area concerned determines whether the object is a vehicle or not according to the distribution state of the area where the distance measured by the measuring means 6 is the same. Judgment means 8;
When the judgment means 8 judges that the target object is a vehicle, the apparatus further includes a notification information outputting means 10 that outputs notification information in accordance with the measured value.

[0009]

[Operation] In the present invention, when emitting electromagnetic waves toward an object, the direction of emission of the electromagnetic waves is sequentially changed to scan a plurality of regions of the object. At this time, it receives the electromagnetic waves that are reflected back from multiple regions of the object and measures the distance to each region according to the time required for the electromagnetic waves. It is determined whether the object is a vehicle or not according to the distribution of areas where the measured values are the same, and when it is determined that the object is a vehicle, the vehicle is The notification information is output according to the measured value.

[0010] Therefore, the object to be detected can be appropriately determined and the distance to the object can be measured with high precision, and notification information can be output appropriately in accordance with the distance to the object.

[0011]

Embodiments Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

First, the overall configuration will be explained with reference to FIG. The oscillator 1 is a Gunn oscillator or the like that oscillates at 10 GHz, and the oscillator 1 is connected to a pulse switch 3 so that the oscillation output from the oscillator 1 is given to the pulse switch 3. This pulse switch 3 is, for example, SPST (S
INGLE PORT SINGLE THROUGH
) switches etc. are used. The pulse switch 3 is connected to the trigger circuit 5 and also to the circulator 7. The circulator 7 is a passive circuit having a plurality of terminals, and power is transmitted only from one terminal to the adjacent terminal without loss. Pulse switch 3 is trigger circuit 5
A pulsed signal is output to the antenna 9 via the circulator 7 in synchronization with the trigger signal from the circulator 7. This results in
Pulsed electromagnetic waves are emitted from the antenna 9 toward an object such as a vehicle. At this time, the scanner 11 sequentially changes the emission direction of the electromagnetic waves from the antenna 9 in synchronization with the trigger signal from the trigger circuit 5. That is, as will be described later, the scanner 11 constitutes a scanning means that scans a plurality of areas of the object by sequentially changing the direction of emission of electromagnetic waves from the antenna 9 constituting the emission means.

The electromagnetic waves reflected by this object are transmitted to the antenna 9.
is received via the detector 1 via the circulator 7.
Enter to 3. The detector 13 is connected to the distance measuring circuit 15, and the signal detected by this detector 13 is transmitted to the distance measuring circuit 1.
given to 5. The distance measuring circuit 15 is connected to the trigger circuit 5 and receives a clock as a reference for time measurement. The distance measuring circuit 15 is a measuring means that measures the distance to each area of the object. That is, by counting the clock, the distance measuring circuit 15 measures the time required for the emitted electromagnetic wave to reflect from the target object and return, and also measures the time required for the emitted electromagnetic wave to reflect from the target object and return to the target object based on the above-mentioned equation (1). Calculate the distance to. Further, the distance measuring circuit 15 is connected to the memory 17 and also to the determining circuit 19.

The microcomputer 21 is connected to the memory 17 and also to the judgment circuit 19. This judgment circuit 19 inputs measurement information from the distance measurement circuit 15, that is, measurement information related to the distance to each area of the object, and determines the distance between the areas where the measured values are the same. It is also a determining means for determining whether or not the object is a vehicle.

The notification circuit 23 is connected to the determination circuit 19. This notification circuit 23 is a notification information output means, and when it is determined that the object is a vehicle, it outputs notification information in accordance with the inter-vehicle distance that is the measured value to the vehicle. The notification circuit 23 has, for example, a buzzer, a chime, a lamp, a voice synthesizer, etc., and when the inter-vehicle distance is less than a predetermined distance, it drives the buzzer, chime, lamp, etc., or calls attention by sound, etc. .

Next, the antenna 9 and the scanner 11 which is its peripheral device will be explained with reference to FIG. A gear 27 is attached to the antenna 9 attached to the rotating shaft 25. A gear 29 that meshes with the gear 27 is fixed to a motor 31, and the vertical angle of the antenna 9 can be changed by rotation of the motor 31. Further, a gear 33 is fixed to the rotating shaft 25. A gear 35 that meshes with the gear 33 is fixed to the motor 37.
By rotating the antenna 9, the antenna 9 can be rotated around the rotation axis 25, and thereby the horizontal angle of the antenna 9 can be changed. Here, if the motors 31 and 37 are configured using stepping motors, the vertical and horizontal angles of the antenna 9 can be easily changed by fixed amounts.

By changing the vertical and horizontal angles of the antenna 9 in this way, it is possible to scan a plurality of areas of the object as shown in FIG. 4. That is, FIG.
When the coordinates of each area are set as shown in , area A(I-
1, J-1), area A (I, J-1), area A (I+1
, J-1), ... are scanned, and then area A(I-1, J
), area A (I, J), area A (I+1, J), ...,
is scanned, and then area A (I-1, J+1), area A (I, J+1), area A (I+1, J+1), ...,
are scanned sequentially.

Next, the operation will be explained with reference to FIG. First, in step S1, the scanner 11 sets the direction of the antenna 9 to a starting point, which is an initial value, and emits electromagnetic waves from the antenna 9. In step S3, the electromagnetic waves reflected and returned by the object are received, and the distance to the corresponding area of the object is measured. This measured data is stored in the memory 17. Next, in step S5, the scanned area,
That is, it is determined whether the measurement point is the final end point, and if it is not the end point, the process returns to step S3 and the distance to the next area is measured.

Thereafter, the distance to the corresponding area is similarly measured each time the scanner 11 scans, and the measured data is stored in the memory 17. If it is determined in step S5 that the measurement point is the end point, the process advances to step S7. In step S7, the distribution of areas having the same distance from among the data stored in the memory 17 is determined.

[0020] In step S7, if there is no area with the same distance, it is determined that no vehicle exists, and the process returns to step S1 to repeat the above-mentioned operation. If it is determined in step S7 that there are regions having the same distance, the process proceeds to step S9, and it is determined whether the regions having the same distance are approaching each other. For example, if the distances between the shaded areas shown in FIGS. 7 and 8 are the same, two areas exist in each of the vertical and horizontal directions.

[0021] If it is determined that areas having the same distance are close to each other as described above, the process advances from step S9 to step S11. In step S11, the number of horizontally adjacent areas is counted. Subsequently, in step S13, the distance to the corresponding area, the scanner 1
The width corresponding to the unit area in the horizontal direction is calculated based on the angle etc. obtained by one scan.

The calculation process in step S13 will be explained in detail with reference to FIG. When the scanning angle of the scanner 11, that is, the scanning angle is θ, and the distance to the corresponding area is R, the width L in the horizontal direction of the unit area is calculated by the following calculation formula.

[0023]L=Rθ...

(2) Subsequently, in step S15, the horizontal length W of the object is calculated. If there are M adjacent areas, the calculation is performed using the following formula.

W=ML=MRθ...

(3) In step S17, it is determined whether the value of the horizontal length W of the object is within a predetermined range, for example, 1.5 m or more and 2.5 m or less. Step S
17, the value of length W is 1.5 m or less, or 2.5 m
If it is determined that the above is the case, it is determined that the object is not a vehicle, and the process returns to step S1 again. Further, in step S17, the value of length W is 1.5 m or more, and 2.
If it is determined that the distance is 5 m or less, it is determined that the object is a vehicle and the process proceeds to step S19. Step S
19, the reference value R0 is set in advance, and step S
It is determined whether the value of the distance R calculated in step 13 is smaller than the reference value R0. If the value of the distance R is greater than the reference value R0 in step S19, it is determined that the steady state is reached and the process returns to step S1.

Further, if the value of the distance R is smaller than the reference value R0 in step S19, it is determined that the state is in an unsteady state, and the process proceeds to step S21, in which a buzzer, chime, lamp, etc. is driven for a certain period of time, or Call attention by voice, etc. This allows the driver to reliably and easily recognize that the inter-vehicle distance is less than a predetermined distance.

Note that the antenna 9 can be configured using a plurality of antennas. For example, a transmitting antenna and a receiving antenna are each provided, and in this case, although the number of antennas increases, a circulator becomes unnecessary. In addition, among multiple antennas, the directivity of the transmitting antenna is required, and the directivity of the receiving antenna is not so required. Electromagnetic waves of the same wavelength or different wavelengths may be sequentially emitted from the antenna and received by a single receiving antenna. By configuring the antenna with a plurality of antennas in this manner, scanning can be performed without providing a movable part, and the object can be detected with even higher accuracy.

Furthermore, if a so-called electronic scanning antenna is used as the antenna 9, which scans the emitted beam by electronically changing the phase of power feeding to each element of a phased array antenna, the emitted beam can be scanned while the antenna itself is fixed. The beam can be scanned and multiple areas of the object can be electronically scanned.

[0028] Furthermore, the electromagnetic wave described above may be configured to irradiate a beam-like light such as a laser beam onto the object. In this case, by reflecting the beam of light using a rotating polyhedron such as a polygon mirror, the irradiation direction of the beam of light can be changed, and multiple areas of the object can be easily scanned. Can be done. Furthermore, by coating the reflective surface of the polygon mirror that reflects the beam-like light with gold or the like, it can be widely used for electromagnetic waves in general, and the reflection efficiency can be improved.

[0029]

[Effects of the Invention] As explained above, according to the present invention, it is determined whether an object is a vehicle or not according to the distribution of areas where the measured values are the same, and it is determined whether the object is a vehicle. If it is determined, the system is configured to output notification information according to the measured value to the vehicle, so the object to be detected is accurately determined and notification information is output appropriately according to the distance to the object. can be output.

[Brief explanation of drawings]

FIG. 1 is a claim correspondence diagram.

FIG. 2 is a block diagram of an embodiment according to the invention.

FIG. 3 is a configuration diagram of the antenna shown in FIG. 2 and its surrounding parts.

FIG. 4 is an explanatory diagram showing scanning directions when scanning multiple regions of a target object.

FIG. 5 is an explanatory diagram showing the coordinates of multiple areas of the object.

FIG. 6 is a flowchart showing the operation of the embodiment according to the present invention.

FIG. 7 is an explanatory diagram showing an example of a case where areas at the same distance are close to each other.

FIG. 8 is an explanatory diagram showing another example where areas at the same distance are close to each other.

FIG. 9 is an explanatory diagram showing calculation of a width corresponding to a unit area in the horizontal direction.

FIG. 10 is a block diagram of a conventional example.

FIG. 11 is an explanatory diagram showing the effect when detecting a vehicle in a conventional example.

FIG. 12 is an explanatory diagram showing an operation when detecting an object other than a vehicle in a conventional example.

[Explanation of symbols]

2 Injection means 4 Scanning means 6 Measurement means 8 Judgment means 10 Notification information output means 1 Oscillator 3 Pulse switch 5 Trigger generation circuit 7 Circulator 9 Antenna 11 Scanner 13 Detector 15 Distance measurement circuit 17 Memory 19 Judgment circuit 21 Microcomputer 23 Notification circuit

Claims (1)

[Claims] 1. An emission means for emitting electromagnetic waves toward an object to be measured, and scanning a plurality of areas set for the object by sequentially changing the emission direction of the electromagnetic waves emitted from the emission means. a scanning means for scanning, a measuring means for measuring the distance from the electromagnetic waves reflected and received by each area of the object scanned by the scanning means to the area, and the distances measured by the measuring means are the same. A determining means for determining whether the target object is a vehicle according to the distribution state of the area, and when the determining means determines that the target object is a vehicle, notification information is provided according to the measured value. What is claimed is: 1. A distance measuring device comprising: notification information output means for outputting notification information.