JPH08166450A - Method and apparatus for detecting obstacle to vehicle - Google Patents

Abstract

PURPOSE: To shorten the receiving time in a system for detecting an obstacle by sequentially transmitting ultrasonic waves and receiving the reflected waves through a plurality of sensors. CONSTITUTION: Receiving operation is ended at a moment of time when receiving a first reflected wave and a switching is made to a next sensor. The obstacle detecting apparatus comprises means 10, 11 for switching a plurality of sensors 1 sequentially, means 12, 15 for driving a sensor Sn selected by the switching means 10, 11 to transmit an ultrasonic wave, and means 13 for detecting the wave transmitted from the sensor Sn and reflected from an object. The obstacle detecting apparatus further comprises means 16 for counting the receiving signals detected by the receiving means 13, and a timing control means 14 for delivering a sensor switching signal and a sensor driving signal, respectively, to the switching means 10, 11 and the transmitting means 12, 15 when the first wave of the receiving signal is detected by the counting means 16.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle obstacle detection method and apparatus for detecting obstacles near a vehicle by utilizing the reflection of ultrasonic waves.

[0002]

2. Description of the Related Art In recent years, as one of the techniques for improving the convenience of a vehicle, there is a device that detects an obstacle in front of and behind the driver that is difficult to recognize from the driver's seat and informs the driver. This type of device detects an obstacle in the vicinity of a vehicle using ultrasonic waves, lasers, radio waves, infrared rays, and the like, and in many cases, an ultrasonic sensor is attached to a bumper.

Among such obstacle detecting devices utilizing ultrasonic waves, there is one of a type that takes in data while sequentially transmitting and receiving a plurality of sensors, and has a simple circuit configuration having only one transmitting / receiving circuit. is there. In such a system, conventionally, the timing of transmission of each sensor is usually regularly performed. That is, the effective detection distance (for example, 2 m) after transmitting the ultrasonic wave for a certain sensor
Continue receiving for a sufficient time for the ultrasound to make a round trip,
After waiting the elapse of the time, the sensor is switched to the next sensor for transmission.

In the method of driving a plurality of sensors while switching them sequentially, when the reception of transmissions from other sensors should be avoided, for example, in order to image the obstacles, the obstacles are marked by the respective sensors. It is used when you want to detect.

[0005]

However, in the above-mentioned conventional method, since a plurality of sensors are periodically switched, the sensor that has transmitted is always transmitted by the next sensor regardless of the presence or absence of an obstacle. It is in a receiving state until then, and it takes a long time to receive one sensor. Therefore, when sending and receiving multiple sensors sequentially, it takes time to acquire data, and the overall processing speed tends to be slow, and it takes time to display obstacles and alarms, such as displaying obstacles as images. When performing the required processing, there is a possibility that an accurate and effective warning cannot be issued.

The present invention has been made in view of the above problems of the prior art, and is for a vehicle in which a receiving time can be shortened in a method of detecting an obstacle by sequentially transmitting and receiving a plurality of sensors. An object is to provide an obstacle detection method and an apparatus therefor.

[0007]

In order to achieve the above object, the method of detecting an obstacle for a vehicle according to claim 1 of the present invention utilizes a reflection of ultrasonic waves while sequentially switching a plurality of sensors. An obstacle detection method for a vehicle for detecting an obstacle in the vicinity is characterized in that the reception process is terminated and the sensor is switched to the next sensor when the first reflected wave is received.

Further, the vehicle obstacle detection device according to the second aspect of the invention is a vehicle obstacle detection device that detects an obstacle in the vicinity of a vehicle by utilizing the reflection of ultrasonic waves. A sensor, a switching unit that sequentially switches the plurality of sensors, a transmitting unit that drives the sensor selected by the switching unit to transmit an ultrasonic wave, and a reflected wave received by the sensor that is driven by the transmitting unit. Receiving means for detecting a received signal, counting means for counting the received signals detected by the receiving means,
And a timing control means for outputting a sensor switching signal and a sensor driving signal to the switching means and the transmitting means, respectively, when the first wave of the received signal is detected by the counting means.

[0009]

In the method of detecting an obstacle for a vehicle according to claim 1 configured as described above, the surface of the obstacle at the shortest distance is detected when the first wave of the reflected wave is received. Immediately after that, the reception process is terminated, the next sensor is switched to and the transmission / reception by that sensor is started. Further, even when the ultrasonic wave is not received within a predetermined time (a time sufficient for the ultrasonic wave to reciprocate the effective detection distance), the next sensor is switched to start the next transmission / reception. That is, when the surface of the obstacle at the shortest distance is detected, the reception is immediately terminated and the sensor is switched to the next sensor, so that the reception time of each sensor can be shortened according to the presence or absence of the obstacle and the distance. This kind of processing is possible when detecting obstacles in the vicinity of the vehicle, what kind of obstacle exists in the shortest distance, and the obstacle behind it is the obstacle in the shortest distance. Since it is not so important as the object, the detection by the individual sensor may be the detection of the surface of the obstacle, that is, the detection of only the first wave of the reflected wave.

Further, in the obstacle detecting device for a vehicle according to the second aspect, when the sensor is selected by the switching means, the transmitting means drives the selected sensor to transmit the ultrasonic wave. The receiving means detects the received signal of the reflected wave received by the sensor driven by the transmitting means, and the counting means counts the received signal detected by the receiving means. At that time, when the first wave of the reception signal is detected by the counting means, the timing control means immediately generates a sensor switching signal and a sensor driving signal and outputs them to the switching means and the transmitting means, respectively.
As a result, the switching unit switches the sensor to be transmitted to the next sensor (the reception of the previous sensor is also terminated), and the switched sensor is driven by the transmitting unit to perform the next transmission. That is, when the first wave of the reflected wave is received, the receiving process is ended and the sensor is switched to the next sensor, so that the method according to claim 1 is realized.

[0011]

Embodiments of the present invention will now be described in detail with reference to the drawings. FIG. 1 is a schematic configuration diagram showing an embodiment of a vehicle obstacle detection device of the present invention. As shown in FIG. 1, the obstacle detection device is roughly divided into an array type sensor 1 for detecting obstacles in the vicinity of a vehicle by utilizing reflection of ultrasonic waves, and an individual array type sensor 1. The transmitting / receiving substrate 2 that sequentially switches the sensors to transmit and receive ultrasonic waves, and outputs the control signals necessary for each part at predetermined timing, and measures the time from transmitting ultrasonic waves to receiving reflected waves A control board 3 for calculating a distance to an object by a predetermined formula, and a display section 6 for displaying on a screen an image of information about an obstacle detected by the array type sensor 1.
And a buzzer circuit 7 that outputs an alarm sound according to the detected distance of the obstacle. The display unit 4 also has a function of numerically displaying the detected distance to the obstacle.

2A and 2B are views showing an example of the array type sensor 1. FIG. 2A is a plan view and FIG. 2B is a front view. As shown in the figure, the array type sensor 1 includes a plurality (17 here) of sensors Sn (n = 1, 2, ..., 17).
Are adjacently arranged in a line on an arc. Each sensor Sn is preferably of the same type and has the same structure and directional characteristics. When the array type sensor 1 is driven, the individual sensors Sn constituting the array type sensor 1 are transmitted and received while being sequentially switched.

FIG. 3 is a schematic configuration diagram of each sensor Sn which constitutes the array type sensor 1. As shown in the figure, each sensor Sn emits an ultrasonic wave of that frequency when an AC voltage is applied and generates an AC voltage of that frequency when a reflected wave is received, and an ultrasonic sensor 6
The conical member 7 for limiting the directivity angle of the sound wave emitted from the predetermined angle θ (for example, about 8 °) to the case 8
It is configured to be stored in. By using the array type sensor 1 as described above, it is possible to detect an obstacle with no blind spot and good azimuth resolution. Therefore, the detected obstacle is imaged by considering its direction data and measured distance data. You can

FIG. 4 is a block diagram of a drive control system of a plurality of sensors Sn which constitute the array type sensor 1. The same members as those in FIG. 1 are designated by the same reference numerals. As shown in the figure, on the transmission / reception board 2, a sensor switching circuit 10 for switching the connection state between the individual sensors Sn forming the array type sensor 1 and a set of transmission / reception circuits, and a sensor switching circuit 1
The sensor selection circuit 11 for instructing the position (for example, number) of the sensor Sn selected by 0, and the sensor S in the array type sensor 1 selected by the sensor switching circuit 10.
A reflected wave from an obstacle received by a transmission circuit 12 that outputs a drive signal (for example, an AC voltage) to n to transmit an ultrasonic wave and a sensor Sn in the array-type sensor 1 selected by the sensor switching circuit 10. And a reception circuit 13 for detecting the reception signal of. Sensor switching circuit 10
Is composed of, for example, a relay. Further, the detection of the reflected wave by the receiving circuit 13 is performed by cutting the after vibration of the transmitted wave with, for example, a threshold value. On the other hand, on the control board 3, a timing control circuit 14 for outputting a signal for controlling the operation timing to each part, and a transmission pulse generation circuit for operating the transmission circuit 12 to generate a transmission pulse for generating the drive signal. 15, an echo count circuit 16 for counting the received waves detected by the reception circuit 13, and a memory 17 for storing the count result of the echo count circuit 16 in association with the corresponding sensor Sn. The sensor selection circuit 11 and the transmission pulse generation circuit 15 are controlled by the timing control circuit 14. The echo count circuit 16 is provided with an echo count gate (not shown) that closes when the first wave of the received wave is detected. Further, the timing control circuit 14 has a timer 18 built-in, and as will be described later, a channel clock is generated when the echo count gate is closed, and the built-in channel counter N (not shown) is incremented by 1, Next sensor S
A control signal for switching to n + 1 is output. In addition, the individual sensors S constituting the array type sensor 1
n (n = 1, 2, ..., 17) is sequentially associated with the value (N = 0, 1, ..., 16) of the channel counter N. In the control board 3, there is further provided a portion (not shown) for measuring the time from transmitting the ultrasonic wave to receiving the reflected wave and calculating the distance to the obstacle by a predetermined formula. Has been.

The switching means is a sensor switching circuit 10 and a sensor selection circuit 11, the transmitting means is a transmitting circuit 12 and a transmission pulse generating circuit 15, the receiving means is a receiving circuit 13, the counting means is an echo count circuit 16, and the timing control means is. Each is configured by the timing control circuit 14.

Next, the processing of the transmission timing of the vehicle obstacle detection device configured as described above will be described with reference to the flowchart of FIG. In the following description, the timing chart of FIG. 6 will be referred to as appropriate. When a measurement start switch (not shown) is turned on to turn on the power to start the program, the timing control circuit 14 resets the value of the internal channel counter N to zero as an initial setting (step S1).

Then, the timing control circuit 14 outputs a sensor switching command to the sensor selection circuit 11 to select the sensor Sn corresponding to the current value of the channel counter N. Sensor selection circuit 11 that has input a sensor switching command
Selects the selected sensor Sn from the transmitter circuit 12 and the receiver circuit 1
The relay in the sensor switching circuit 10 is switched so as to be connected to No. 3 (step S2). Further, the timing control circuit 14 outputs the sensor switching command to the sensor selection circuit 11 at the same time as outputting the transmission command to the transmission pulse generation circuit 15 in step S2, and opens the echo count gate in the echo count circuit 16 (FIG. 6). reference). The transmission pulse generation circuit 15 which has input the transmission command outputs a transmission pulse having a predetermined frequency to the transmission circuit 12, and the transmission circuit 12 drives the sensor Sn in the array type sensor 1 selected by the sensor switching circuit 10 at the same frequency. A signal (for example, AC voltage) is output to transmit ultrasonic waves (step S3). The transmission wave transmitted from the sensor Sn in the array type sensor 1 has a waveform as shown in FIG. 6, for example. When a transmission command is output and an ultrasonic wave is transmitted from one sensor Sn in the array type sensor 1, the timing control circuit 14 activates the internal timer 18 (step S4).

Then, the timing control circuit 14 judges, based on the timer 18, whether or not a preset time (a time sufficient for the ultrasonic waves to reciprocate the effective detection distance) has elapsed (step S5). ), If the result of this determination is that the predetermined time has not elapsed, it waits in the receiving state. That is, the reflected wave returned by hitting the obstacle with the ultrasonic wave transmitted in step S3 is
Only the sensor Sn selected in 2 receives the signal, and the received signal is input to the receiving circuit 13. The receiving circuit 13 detects the received wave of the reflected wave received by cutting the after vibration of the transmitted wave with a threshold value or the like, and sends it to the echo count circuit 16 (step S6). The received wave has a waveform as shown in FIG. 6, for example.

In step S7, if no reflected wave is received as a result of the receiving process in step S6, step S7 is performed.
Returning to step 5, if it is received, the reception is immediately terminated and the process of switching to the next sensor Sn + 1 is performed.

That is, when the echo count circuit 16 detects that the first wave of the received wave is input, the echo count circuit 16 immediately closes the echo count gate (step S8) when the first wave of the received wave is detected. In response, the timing control circuit 14 generates a channel clock (step S9) and increments the channel counter N by 1 (step S10) (see FIG. 6). Then, it is determined whether the measurement stop signal is input (step S
11) If the measurement stop signal is input, the measurement is stopped, but if it is not input, it is determined whether the current value of the channel counter N is the maximum value M (= 16) or more. (Step S12). As a result of this judgment, if the current value of the channel counter N is less than the maximum value M, that is, if the drive of the sensor Sn in the array type sensor 1 has not completed one cycle, the process returns to step S2 and the current value of the channel counter N is maximum. If the value is M or more, that is, if the driving of the sensor Sn in the array type sensor 1 has completed one cycle, the process returns to step S1. That is, in any case, switching to the next sensor Sn + 1 and a new transmission / reception of ultrasonic waves is started. At this time, actually, the timing of writing data to the memory 17 and switching the sensor Sn is performed at the portion indicated by the arrow A in FIG. Also,
Timer 18 before returning to step S1 or step S2
Is reset.

As described above, when the reception is performed within the predetermined time, the reception is immediately terminated when the first reflected wave is received, that is, when the surface of the obstacle at the shortest distance is detected. Then, the sensor is switched to the next sensor and transmission / reception is started by that sensor, but such processing is possible when detecting obstacles near the vehicle, what kind of obstacle exists at the shortest distance? Is important, and the obstacles behind it are not as important as the obstacles at the shortest distance. Therefore, the detection by each sensor is the detection of the surface of the obstacle, that is, the detection of only the first wave of the reflected wave. But it's okay.

On the other hand, if no signal is received within the predetermined time as a result of the determination in step S5, immediately step S8 is performed.
Then, the process ends and the switching process to the next sensor is performed.

Therefore, according to this embodiment, when the first wave of the received wave is detected within a predetermined time, that is, when the surface of the obstacle at the shortest distance is detected, the reception is immediately terminated and the next sensor is detected. Therefore, the reception time of each sensor Sn can be shortened according to the presence or absence of an obstacle and the distance. At this time, each sensor Sn in the array sensor 1
The timing of the transmitted wave is irregular depending on the presence or absence of obstacles and the distance (see FIG. 6).

As a result, when a plurality of sensors Sn are sequentially switched to transmit and receive like the array type sensor 1, the overall receiving time can be shortened even with a simple circuit configuration having only one set of transmitting and receiving circuits. be able to. Therefore, for example, when performing an image display of an obstacle that requires a long processing time, the shorter the distance to the detected obstacle is, the shorter the reception time of the sensor Sn is, and the obstacle is shortened in time. Since it is possible to display the image of, the effective and accurate warning can be issued more effectively and quickly.

In this embodiment, the array type sensor 1 is used as an example of a method of sequentially switching a plurality of sensors for transmission and reception, but the present invention is not limited to this. The present invention is applicable in any case where the reception of transmissions from other sensors should be avoided.

The circuit configurations shown in FIGS. 1 and 4 are merely examples, and needless to say, are not limited to these. The method of the present invention can be implemented by a circuit configuration other than those shown in FIGS.

[0027]

As described above, according to the vehicle obstacle detection method of the first aspect of the present invention, the first reflected wave
When the wave is received, the reception process is terminated and the sensor is switched to the next sensor, so the reception time of each sensor can be shortened according to the presence or absence of obstacles and the distance, thus shortening the overall measurement reception time. be able to.

Further, according to the vehicle obstacle detection device of the second aspect, when the first wave of the reflected wave is received, the reception process is terminated and the sensor is switched to the next sensor. Is realized and the reception time can be shortened.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram showing an embodiment of a vehicle obstacle detection device of the present invention.

FIG. 2 is a diagram showing an example of an array type sensor.

FIG. 3 is a schematic configuration diagram of individual sensors forming an array type sensor.

FIG. 4 is a block diagram of a drive control system for a plurality of sensors that form an array sensor.

FIG. 5 is a flowchart showing processing of transmission timing.

FIG. 6 is a timing chart used to explain FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Array type sensor (a plurality of sensors) 10 ... Sensor switching circuit (switching means) 11 ... Sensor selection circuit (switching means) 12 ... Transmitting circuit (transmitting means) 13 ... Receiving circuit (receiving means) 14 ... Timing control circuit ( Timing control means) 15 ... Transmission pulse generation circuit (transmission means) 16 ... Echo count circuit (counting means)

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁶ Identification number Internal reference number FI Technical indication location G08G 1/16 C (72) Inventor Norihiro Nishio 2-10-19 Step-in, Ueda City, Nagano Prefecture Ueda Nihon Radio Co., Ltd. (72) Inventor Takao Yamakoshi 2-1019, Ueda City, Nagano Prefecture Ueda Nihon Radio Co., Ltd. (72) Inventor Akihiko Okabe 2-10, Ueda City, Nagano Prefecture No. 19 Ueda Nihon Radio Co., Ltd.

Claims (2)

[Claims] 1. A vehicle obstacle detection method for detecting an obstacle in the vicinity of a vehicle by utilizing the reflection of ultrasonic waves while sequentially switching a plurality of sensors, and receiving processing at the time of receiving the first reflected wave. The method for detecting an obstacle for a vehicle is characterized by terminating the process and switching to the next sensor. 2. A vehicle obstacle detection device for detecting obstacles in the vicinity of a vehicle by utilizing the reflection of ultrasonic waves, and a plurality of sensors (1) for transmitting and receiving ultrasonic waves, and the plurality of sensors (1). Switching means (1
0, 11) and a transmitting means (1) for driving the sensor (Sn) selected by the switching means (10, 11) to transmit ultrasonic waves.
2, 15), a receiving means (13) for detecting a reception signal of a reflected wave received by a sensor (Sn) driven by the transmitting means (12, 15), and a receiving means (13) for detecting the received signal. Counting means (16) for counting received signals, and sensor switching signals and sensor driving signals when the first wave of the received signals is detected by the counting means (16), respectively. Timing control means (1 to output to the transmission means (12, 15)
4) An obstacle detection device for a vehicle, comprising: