JPH07128444A - Distance measuring equipment for vehicle - Google Patents

Abstract

PURPOSE:To obtain a distance measuring equipment for vehicle which detects relationships in relative positions of a driver's own vehicle with vehicles in front and in the rear in real time and makes it possible to distinguish vehicles on the lane of the own vehicle from vehicles on other lanes. CONSTITUTION:Ultrasonic sensors 11 and 12 for transmission are provided in the front and the rear of a vehicle so as to transmit ultrasonic burst signals and ultrasonic sensors 12 and 14 for reception are provided in the front and the rear of the vehicle so as to receive the ultrasonic burst signals from other vehicles, while time information from a satellite is received by a GPS(global positioning system) receiver 16. In an information processing means 19, the ultrasonic burst signals are made to be transmitted from the ultrasonic sensors 11 and 13 synchronously with the information from the satellite, the time of arrival of the ultrasonic burst signal from a vehicle in front or in the rear received through the ultrasonic sensor 12 or 14 for reception is detected synchronously with the time information from the satellite and a relative distance to the vehicle in front or in the rear is determined on the basis of a difference between these two times.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle distance measuring device, and more particularly to a vehicle distance measuring device for measuring the position of a vehicle traveling in front of and behind the vehicle using ultrasonic waves. is there.

[0002] In order to prevent a vehicle accident such as a rear-end collision, it is necessary that the inter-vehicle distance from other vehicles traveling in front of and behind the vehicle be properly maintained. It is desirable not only to rely on the above, but also to equip some distance measuring device to measure the distance to the vehicle traveling in the front and back, and to give an alarm if it is inappropriate.

The vehicle distance measuring device used for such a purpose can detect the relative positions of the front and rear vehicles in real time and display them to the driver, and also has high reliability and contribute to safety. It needs to be one.

[0004]

2. Description of the Related Art FIG. 10 shows a conventional vehicle distance measuring method, which illustrates an example of using a reflection method. Of these, the configuration is shown in FIG.
(B) shows a timing chart of the transmitted wave and the received wave.

In this conventional system, an ultrasonic wave signal composed of a burst wave is transmitted from the ultrasonic wave sensor 2 provided in the vehicle 1.
The other vehicle is detected by receiving the reflected wave from the other vehicle 3 in the front (or the rear) with an ultrasonic sensor shared with the transmission or dedicated. That is, the time difference between the transmitted wave and the received wave is T
Assuming [sec], the inter-vehicle distance L [m] is the sound velocity C
[M / sec] is measured by the relationship of the following equation.

L = (T / 2) × C

As described above, in the reflection type vehicle distance measuring device, the time from when the ultrasonic signal is transmitted from the own vehicle to when it reaches another vehicle, is reflected and returns to the own vehicle again is measured. Then, the inter-vehicle distance with other vehicles is calculated.

[0008]

In the reflection type vehicle distance measuring device, the area (distance) that can be detected by the ultrasonic sensor is limited by the decrease in the S / N ratio due to the attenuation of the ultrasonic signal in the air. receive. For this reason,
At present, this method is limited to use for detecting an obstacle when entering a garage.

Further, the reflection type vehicle distance measuring device has a problem that it malfunctions by detecting a signal reflected by unevenness on the road such as a stone.

11A and 11B are diagrams for explaining a malfunction due to the reflection method. FIG. 11A shows a detection area, and FIG. 11B shows a received wave when a stone or the like exists. . As shown in FIG. 11, when there is unevenness on the road such as stones 5 in the detection area 4 of the vehicle 1, a reflected wave A and a reflected wave B by the forward vehicle 3 are generated. Since the two reflected waves A and B are of the same quality to the vehicle distance measuring device, they cannot be distinguished by the vehicle distance measuring device and malfunction.

Further, since the distance measuring device for a vehicle of this system measures only the distance to another vehicle within the detection area, it sometimes detects a vehicle traveling in another lane and becomes useless. There was an inconvenience of generating the alarm.

[0012]

It is an object of the present invention to improve the inconvenience of the conventional example, and in particular, it is possible to detect the relative position of a vehicle located in front of and behind the own vehicle in real time, display the same to the driver, and measure the relative position. (EN) Provided is a vehicle distance measuring device which has a wide range, eliminates erroneous operation due to unevenness on a road, and can distinguish between a vehicle traveling in another lane in parallel and a vehicle traveling in its own lane. That is the purpose.

[0013]

SUMMARY OF THE INVENTION According to the present invention, a transmitting ultrasonic sensor for transmitting an ultrasonic burst signal provided in front of and behind a vehicle and an ultrasonic burst signal from another vehicle provided in front of and behind the vehicle are provided. The receiving ultrasonic sensor, the GPS receiver for receiving the time information from the satellite, the transmitting ultrasonic sensor transmitting the ultrasonic burst signal in synchronization with the time information from the satellite, and the receiving ultrasonic wave. The arrival time of the ultrasonic burst signal received from the front vehicle or the rear vehicle received via the sensor is detected in synchronization with the time information from the satellite, and the relative distance between the front vehicle or the rear vehicle and the host vehicle is detected from the difference between the two times. And an information processing means for obtaining the information. This aims to achieve the above-mentioned object.

[0014]

The ultrasonic sensors 11 and 13 for transmission are provided in front of and behind the vehicle to transmit ultrasonic burst signals, and the ultrasonic sensors 12 and 14 for reception are similarly provided in front and rear of the vehicle to ultrasonic burst from other vehicles. Receive the signal. Further, the GPS receiver 16 receives time information from the satellite.

The transmitting ultrasonic sensor 1 is synchronized with the time information from the satellite received via the GPS receiver 16.
It is also said that ultrasonic burst signals are transmitted from 1, 13
The arrival time of the ultrasonic burst signal from the front vehicle or the rear vehicle received via the reception ultrasonic sensors 12 and 14 is detected in synchronization with the time information from the satellite, and the front vehicle or the rear vehicle is detected from the difference between the two times. Find the relative distance to.

Therefore, according to the present invention, it is possible to detect the relative distance between the vehicle and the front and rear vehicles in real time and notify the driver of the relative distance.

Further, in this case, the information processing means 19 calculates from the distance between the front vehicle and the rear vehicle, which is obtained by two receiving ultrasonic sensors provided in front of and behind the vehicle, and the front vehicle is operated. Alternatively, the relative position between the rear vehicle and the own vehicle is obtained.

Therefore, according to the present invention, it is possible to issue a warning by distinguishing between a vehicle traveling in another lane and a vehicle traveling in its own lane.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. FIG. 1 shows a configuration of an embodiment of a vehicle distance measuring device of the present invention, and illustrates a system configuration of the device of the present invention provided in a vehicle. FIG. 2 is a timing chart showing signals of respective parts in the device shown in FIG. Further, FIG. 3 shows the resonance frequency of each sensor.

In the embodiment shown in FIG. 1, ultrasonic sensors 11 and 13 for transmitting the ultrasonic burst signals, which are provided in front of and behind the vehicle, and ultrasonic waves from other vehicles, which are provided in front of and behind the vehicle, are used. Ultrasonic sensor for reception 1 that receives a burst signal
2 and 14, a GPS receiver 16 for receiving time information from the satellite, and an ultrasonic burst signal transmitted from the ultrasonic sensors 11 and 13 for transmission in synchronization with the time information from the satellite. The arrival time of the ultrasonic burst signal from the front vehicle or the rear vehicle received via the ultrasonic sensors 12 and 14 for the vehicle is detected in synchronization with the time information from the satellite, and the difference between the both times is used to detect the front vehicle or The configuration is such that an information processing means 19 for determining the relative distance to the rear vehicle is provided.

More specifically, in the system shown in FIG. 1, the relative position of the vehicle before and after the own vehicle is measured using ultrasonic waves. In this case, unlike the conventional method, the object is achieved by detecting the direct waves emitted from the front and rear vehicles. In order to measure the distance by the direct wave, it is necessary to synchronize the time between the vehicles, but in the present invention, a global positioning system (GPS), which is a positioning system using an artificial satellite, is used. Use this to synchronize the time.

Therefore, each vehicle has a GPS receiver 16 and transmits an ultrasonic signal in synchronization with a time signal 22 based on satellite radio waves received via a GPS antenna 15.
If another vehicle exists near the front and rear of the own vehicle, the processing device 19 including a processing computer is generated by the signals 26 and 28 of the other vehicle received by the receiving ultrasonic sensors 12 and 14 of the own vehicle. By processing with
The position of another vehicle is calculated.

The operation of each device in this system will be described below with reference to FIGS. 1 to 3.

In FIG. 1, the transmitting ultrasonic sensor 11,
Numeral 13 is driven by burst signals 23 and 29 which are outputs from the transmission circuits 17 and 20, and transmits a predetermined ultrasonic wave. The period T _b of the high frequency signal forming the burst signal is
It depends on the resonance frequency of the transmitting ultrasonic sensors 11 and 13. For example, in the example of FIG. 2, one burst signal 23 is “T _b = 1 / f ₁ ”, and the other burst signal 29 is “T _b = 1 / f ₂ ”.

Here, if another vehicle exists before and after the own vehicle, this ultrasonic wave is received by the receiving ultrasonic sensor of the other vehicle. One ultrasonic sensor for transmission is installed in each of the front and the rear of the vehicle. The receiving ultrasonic sensors 12 and 14 also receive ultrasonic waves transmitted from vehicles traveling in front of and behind the vehicle.

The resonance frequency of each ultrasonic sensor is, for example, as shown in FIG. 3 in order to distinguish it from the reflected wave of the ultrasonic wave transmitted by the vehicle.
Is assigned as. In addition, two ultrasonic sensors for reception are provided at each of the front and rear in order to detect the positions of the ultrasonic sources of the front and rear vehicles. The two receiving ultrasonic sensors are
Fix it at the same height from the road surface with a distance left and right.

Reference numeral 15 indicates a GPS antenna. This G
The PS antenna 15 receives a distance measurement radio wave transmitted from a GPS artificial satellite. Reference numeral 16 is a GPS receiver that receives this radio wave. GPS receiver 16
Although the position of the receiver is detected from the electric signal input via the GPS antenna 15, as another function, the precise time can be detected from the radio wave. GPS
The receiver 16 periodically transmits the time signal 22 to the information processing means 19 for synchronization.

In all the systems equipped with this device, it is the burst signals 23 and 29 that drive the ultrasonic sensor for transmission that need to be time synchronized, and the time signal 22 must have high time accuracy. However, the transmission period Tgps need not be the same in all systems.

Since the information processing means 19 has a built-in clock having a sufficiently high accuracy for a short time and can accurately divide the time signal 22, the period T of the time signal 22 is reduced.
The gps may be larger than the cycle T for measuring the front and rear vehicles.

The information processing means 19 receives the time signal 22 from the GPS receiver 16 and corrects the built-in clock. Then, at appropriate timing and cycle, the transmission circuits 17, 20
The transmission instruction signals 25 and 27 are transmitted to.

The transmission timings and periods of the transmission instruction signals 25 and 27 are arranged to be the same in all the systems equipped with this device. For example, it is necessary to negotiate the period T more than the time when the ultrasonic wave is sufficiently attenuated in the air so that the signal input to the receiving ultrasonic sensor is not mistaken when it is transmitted.

Further, the transmission instruction signals 25 and 27 do not necessarily have to be transmitted at the same time, and a method of repeating them alternately may be considered. Then, since only one of the front and back ultrasonic waves exists at a certain time, the front and rear ultrasonic sensors
The same can be used.

Reference numerals 18 and 21 are receiving circuits. This receives the sensor signals 24 and 30 sent from the receiving ultrasonic sensors 12 and 14, performs appropriate amplification and noise removal, etc., and produces processed sensor signals 26 and 28, and the information processing means 19 Send to.

In FIG. 1, the sensor signals 24 and 30 and the processed sensor signals 26 and 28 are shown.
Actually, since two sensors are used as the receiving ultrasonic sensors 12 and 14, respectively, the sensor signals 24 and 30 are used.
The processed sensor signals 26 and 28 are signals of two channels.

In FIG. 2, only one waveform is shown as an example of the sensor signal. Although an example of the processed sensor signal is not shown in FIG. 2, this signal is obtained by removing noise from the sensor signal and amplifying it to a level suitable for capturing the signal in the information processing means 19. , Is almost the same as the sensor signal.

The information processing means 19 includes receiving circuits 18 and 2
The processed sensor signals 26 and 28 are taken in from 1 to calculate the relative positions of the transmitting ultrasonic sensors of the front and rear vehicles with respect to the own vehicle.

FIG. 4 is a block diagram showing the configuration of the processing device. Further, FIG. 5 is a flowchart showing the processing of the information processing means 19. The operation of the information processing means 19 will be described below with reference to both figures.

In FIG. 4, since the internal clock 31 receives the time signal 22 from the GPS receiver 16 and is corrected, the internal clock 31 has sufficiently high accuracy. The internal clock 31 is the internal bus 3
7, the CPU 34 controls the transmission instruction signals 25 and 27 at a predetermined timing in order to synchronize the synchronization timing in all vehicles equipped with the device of the present system. . Also,
At the same time that the transmission instruction signal is output, a trigger signal is output to the analog-digital (A / D) converter 32.

The A / D converter 32 converts the processed sensor signals 26 and 28, which are analog signals, into digital signals. The input of the A / D converter 32 is the processed sensor signal 2
6, 28, and the number of inputs is the number of reception ultrasonic sensors. The A / D conversion unit 32 has a random access memory (RAM) inside, and the data converted into a digital signal is stored in a predetermined location of this RAM. The storage position of the data is determined by which ultrasonic sensor for reception is from and the elapsed time after the start of A / D conversion.

The A / D conversion is started by a trigger signal from the internal clock 31. The A / D conversion is performed at a predetermined sampling period until a certain set time. After that, A / D conversion is not performed until a trigger signal from the internal clock 31 is input. R inside the A / D converter 32
The AM is read by the CPU 34 via the internal bus 37. When the data acquisition for a predetermined time is completed, an interrupt is generated to the CPU 34 via the internal bus 37 to notify that the data acquisition is completed.

The external interface unit 33 outputs the presence / absence of front and rear vehicles and, if present, the relative position data of the vehicles to an external device such as a display device.

The processing device 19 controls other devices and processes data according to a program stored in the read-only memory (ROM) 36 in advance.

FIG. 6 illustrates the principle of positioning with respect to the front and rear vehicles. In FIG. 6A, the ultrasonic signal transmitted from the vehicle in front (rear) is an ultrasonic sensor for receiving the own vehicle. FIG. 6B illustrates the timing of each signal when reaching the position.

In FIG. 6, when the propagation time until the ultrasonic signal reaches the receiving ultrasonic sensors 1 and 2 is T _{1 and} T ₂ , the transmitting ultrasonic wave of the vehicle ahead (or rear) Distance L ₁ between the sensor and each of the receiving ultrasonic sensors 1 and 2 of the vehicle
L ₂ can be calculated by the following equation.

L ₁ = C × T ₁ (1)

L ₂ = C × T ₂ (2)

L ₁ ² = (x−x ₁ ) ² + (y−y ₁ ) ² (3)

L ₂ ² = (x−x ₂ ) ² + (y−y ₂ ) ² (4)

Here, x and y are the coordinate positions of the vehicle ahead (rear) when the own vehicle is the coordinate origin, x _{1 and} y ₁ are the coordinate positions of the receiving ultrasonic sensor 1, and x _2, y ₂ indicates the coordinate position of the receiving ultrasonic sensor 2, respectively.

Thus, when the position of each receiving ultrasonic sensor of the vehicle is known, the distances L _{1 and} L ₂ are known,
By solving the equations (1) to (4), the positions (x, y) of the front (or rear) vehicle with respect to the own vehicle can be obtained. Two solutions are obtained by the equations (3) and (4), but the solution indicating the front of the ultrasonic sensor of the vehicle indicates the true position, and the solution indicating the rear is a meaningless solution.

This device is basically a device for checking the presence / absence of front and rear vehicles and indicating the position of the front and rear vehicles, if any. By connecting this device with an external device, the following operation can be considered. it can.

That is, the positions of the front and rear vehicles can be displayed on the display device to show the driver. If necessary, a warning sound can be generated and the display can be flashed to call attention, so that the driver can drive safely.

Further, since it is possible to distinguish between a vehicle traveling in the adjacent lane and a vehicle traveling in the own lane, it is possible to display only the vehicles in front of and behind the own lane, thus reducing the amount of information. Thus, the mental burden on the driver can be reduced.

By doing so, it is possible to substitute for the driver's eyes when the visibility is poor in the event of fog, rain, etc., which is extremely effective for safe driving.

Further, by using the position data obtained at this time, the platooning can be performed by automatically controlling the steering and the acceleration / deceleration so that the host vehicle follows the vehicle in front.

FIG. 7 is a flow chart showing a control method during platooning. The difference between the current position of the vehicle ahead and the position where the vehicle ahead should exist (reference position) is detected, and the target steering amount and speed are calculated from this and the current speed and steering amount of the own vehicle. , Controls the steering control device according to the target steering amount,
By controlling the drive control device according to the target speed, it is possible to carry out platooning while always keeping the inter-vehicle distance from the former constant.

As another application, it is easy to add a function of issuing a warning to the following vehicle that there is a risk of a rear-end collision, thereby avoiding the risk of a rear-end vehicle colliding with the own-vehicle. be able to.

FIG. 8 illustrates a warning method when a rear-end collision warning is given to a following vehicle. In the figure, a symbol a shows a waveform of a burst wave when there is a danger of a rear-end collision, and a symbol b represents. The waveform of the burst wave when there is no danger of collision is shown.

That is, when the distance to the preceding vehicle is too short and there is a risk that the following vehicle may collide with the brake operation of the own vehicle, as shown in FIG. Send out. In the following vehicle, information processing means 1
9 can check the presence or absence of a burst wave of a fixed cycle in the received signal, and when it detects this, it can notify the driver of that fact via an external device to receive a warning. The burst wave is strong against noise and is suitable as a warning method. On the other hand, when there is no danger of a following vehicle colliding with you,
The burst wave b shown in FIG. 8 is transmitted only once every distance measurement cycle.

When the vehicle distance measuring device of this embodiment is compared with the conventional system, in the conventional system, it is necessary to propagate the ultrasonic signal over the round trip distance to the reflector, but in the system of this embodiment. Since the direct wave is used, the measurable distance can be doubled. Further, in the case of vehicles at the same distance, the S / N ratio in the case of the direct wave system is higher than that in the case of the reflection system.

In the reflection method, when there is a reflecting object such as a stone nearer to the vehicle than the vehicle to be detected, the reflection signal from the stone or the like returns before the reflection signal from the vehicle to be detected. , Indistinguishable. Further, in the reflection method, multiple reflections occur from various parts of the vehicle to be detected, such as a bumper, tires, and a rear window, so that they cannot be distinguished. Thus, in the conventional method, the reliability of the distance measurement becomes low due to the multipath signals.

FIG. 9 illustrates the influence of multipath in the case of the method of this embodiment. FIG. 9A shows the occurrence of multipath reflection, and FIG. It shows the timing with the multipath received wave.

In the method of this embodiment, since the direct wave from the vehicle to be detected is received, the input signal from the vehicle to be detected is received earliest by the receiving ultrasonic sensor.
The multipath input signal generated by the reflection of the wall or the road surface arrives at the receiving ultrasonic sensor later than the direct wave.
Therefore, since such multipath signals can be easily identified and removed, highly reliable distance measurement can be performed.

[0064]

As described above, according to the present invention,
Since it is possible to detect the relative positional relationship between the own vehicle and the vehicles in front of and behind it in real time and notify the driver, it is possible to improve the reliability of the device, and in particular, to identify the vehicle traveling in another lane and the own lane. Since it can be distinguished from the traveling vehicle, it is possible to provide an unprecedented excellent vehicle distance measuring device that does not give the driver an extra warning and can enhance the reliability of the warning. .

Further, according to the present invention, since the positions of the front and rear vehicles can be detected, the steering and acceleration / deceleration can be automatically controlled by using the position data, and the platoon traveling of a plurality of vehicles can be performed. It can be automated.

In the method of the present invention, the artificial satellite (GP
Since the highly accurate time information from S) is used, the positions of the front and rear vehicles can be accurately measured as a result. Further, in the method of the present invention, the distance is measured using the direct waves from the front and rear vehicles, so that the measurable distance range is long and the S / N is high. Also, malfunction due to multipath propagation of ultrasonic waves due to unevenness of the road will not occur. Further, when the own vehicle and the preceding vehicle approach each other, it is possible to warn the following vehicle and call attention.

[Brief description of drawings]

FIG. 1 is a diagram showing an embodiment of a vehicle distance measuring device of the present invention.

FIG. 2 is a timing chart showing signals of various parts in the device shown in FIG.

FIG. 3 is a diagram showing a resonance frequency of each sensor.

FIG. 4 is a block diagram showing a configuration of a processing device.

FIG. 5 is a flowchart showing processing of the processing device.

FIG. 6 is an explanatory diagram showing the principle of positioning for front and rear vehicles,
FIG. 6A shows the positional relationship between the front and rear vehicles, and FIG. 6B is an explanatory diagram showing the reception time of the received wave.

FIG. 7 is a flowchart showing a control method during platooning.

FIG. 8 is a diagram illustrating a warning method when a rear-end collision warning is given to a following vehicle.

9A and 9B are explanatory views showing the influence of multipath in the case of the system of the present invention, FIG. 9A shows a propagation path from a vehicle ahead, and FIG. 9B shows a received waveform at that time.

FIG. 10 is an explanatory view showing a conventional vehicle distance measuring method,
FIG. 10A shows the propagation path of the reflected wave, and FIG.
Indicates the received waveform at that time.

11 is an explanatory diagram showing an example of a post-operation in a conventional example, FIG. 11 (a) shows a propagation path of a reflected wave, and FIG.
(B) shows the received waveform at that time.

[Explanation of symbols]

 11 ultrasonic wave sensor for transmission 12 ultrasonic wave sensor for reception 13 ultrasonic wave sensor for transmission 14 ultrasonic wave sensor for reception 16 GPS receiver 19 information processing means

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI technical display location G01S 15/60 8113-5J 15/93

Claims (2)

[Claims] 1. An ultrasonic sensor for transmission which is provided in front of and behind a vehicle and which transmits an ultrasonic burst signal, and an ultrasonic sensor for reception which is provided in front of and behind the vehicle and receives ultrasonic burst signals from other vehicles. , G receiving time information from satellite
A PS receiver, a front vehicle or a rear vehicle that transmits an ultrasonic burst signal from the transmitting ultrasonic sensor in synchronization with the time information from the satellite and receives the ultrasonic burst signal via each of the receiving ultrasonic sensors. And an information processing means for detecting the arrival time of the ultrasonic burst signal from the satellite in synchronization with the time information from the satellite and determining the relative distance between the vehicle ahead and the vehicle behind from the difference between the two times. Distance measuring device for vehicles. 2. The vehicle distance measuring device according to claim 1, wherein front and rear vehicles are equipped with reception ultrasonic sensors individually in front of and behind the vehicle, and are determined by the reception ultrasonic sensors. A distance measuring device for a vehicle, characterized in that the information processing means obtains a relative position with respect to a front vehicle or a rear vehicle from the distance to the vehicle.