JPH0255756B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to an object detection device that detects objects such as obstacles.

Conventional technology Conventionally, an object detection device used for detecting obstacles while driving a car, for example, emits directional radio waves or ultrasonic waves from a transmitter, and receives reflected waves from the object using a receiver. This method is used to detect objects such as obstacles, but it requires a pair of transmitters and receivers, making the device complex, and since it has directivity, it is difficult to detect objects in close proximity. It has become something that creates a dead zone.

Conventionally, a pair of antennas is provided and a high-frequency signal of the same frequency is applied to each antenna, and when an object to be detected faces the pair of antennas, an imbalance in capacitance between each antenna and the object occurs. A device that detects objects according to the difference in oscillation frequency has been developed (Special Publication Publication No. 47-7852).
In such a device, two systems of antennas and oscillators are required, making the device complicated, and the object is evenly positioned with respect to the pair of antennas, making it difficult to connect each antenna to the object. If there is no unbalance in the capacitance between the
Furthermore, it is not possible to detect objects with directionality.

Purpose The present invention was made in consideration of the above points, and
With a simple configuration, objects such as obstacles approaching in front of the vehicle can be detected reliably and directionally and a warning can be issued, while also preventing the influence of disturbances caused by objects in directions other than the detection target, especially the vehicle body. To provide an object detection device that can eliminate false alarms caused by falling raindrops, etc.

Configuration In order to achieve the object, the object detection device according to the present invention provides a plurality of sensors made of electrode members with directionality, and uses the difference in object detection sensitivity of each sensor to provide directionality in object detection. It uses a multi-sensor system, and detects objects and issues an alarm in response to changes in frequency signals based on changes in stray capacitance between each sensor and the object to be detected.

In particular, the present invention is characterized in that when an object in a direction other than the detection target subsequently moves in the detection target direction, this is detected and the alarm is forcibly canceled.

Hereinafter, one embodiment of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 2 is a circuit diagram showing the basic principle of object detection according to the present invention. When a frequency signal is applied to the electrode member 1 via the network 3 consisting of divided resistors,
Focusing on the fact that the stray capacitance C between the electrode member 1 and the object O (O1, O2) changes depending on the distance between them, and the AC output voltage at the voltage dividing point of the network 3 changes, the electrode member 1 By using the sensor as a sensor, the state of approach of the object O is detected by detecting the falling state of the output voltage when the object O approaches the sensor.

At that time, if the sensor (electrode member) 1 is rod-shaped as shown in the figure, for example, the sensor 1
This means that an object O1 in the horizontal direction and an object O2 in the vertical direction are detected respectively.

Therefore, especially in the present invention, when the object O2 in the vertical direction is not a detection target, the object O2 in the horizontal direction of the target sensor 1 is detected.
In order to be able to selectively detect only 1,
As shown in FIG. 3, the sensors 11 and 12 in at least two object detection systems are provided in parallel, and each object O1,
Differences in detection sensitivity depending on the position of O2 are used to provide directionality to object detection.

That is, there are stray capacitances C1 and C2 between the sensors 11 and 12 and the ground, respectively, and when the object O approaches the sensors 11 and 12, the stray capacitances C1 and C2 are
2 increases, and the amount of attenuation of the frequency signal in the network 3 (31, 32) corresponding to each sensor 11, 12 increases. However, depending on the direction in which the object O approaches the sensors 11, 12, This results in a difference in the attenuation of frequency signals in each network 31, 32. Now, in the relationship shown in FIG. 3, the object O1 is
Considering the case where the object O2 approaches from the horizontal direction and the object O2 approaches from the vertical direction, since the object O1 is approximately equidistant from each sensor 11 and 12, the changes in its stray capacitance are approximately equal. While the frequency signal attenuation in each network 31, 32 is approximately equal, in the case of the object O2, there is a distance difference between each sensor 11, 12, and the sensor 12 corresponding to the one with a longer distance is generated. The amount of attenuation in network 32 is less than the amount of attenuation in network 31 corresponding to the other sensor 11. Therefore, by looking at the difference in the amount of attenuation of the frequency signal in each network 31, 32 corresponding to the two sensors 11, 12, it becomes possible to detect an object with directionality.
At this time, for example, the approach state of the object O1 in a predetermined direction is detected based on the fact that the amount of attenuation of the frequency signal in each network 31, 32 is equal. Further, when an object O2 that is initially in a direction other than the detection target later comes to a predetermined direction that is a detection target, the object O2 is first detected by the sensor 11 with sufficient sensitivity, and then the sensor 12 detects the object O2 with a time difference. It will also be detected by

FIG. 1 shows an embodiment of an object detection device according to the present invention constructed based on the above-mentioned basic principle, and here shows the construction when two sensors are used. That is, an oscillator 2 that generates a constant frequency signal, networks 31 and 32 consisting of resistance divider circuits provided in parallel on the output side of the oscillator 2, and networks 31 and 32 that are connected at the dividing points of each network 31 and 32, respectively. Connected sensors 11, 12
, bandpass filter amplifiers 41 and 42 that perform noise removal and amplification processing on the high-frequency output voltages from the networks 31 and 32, respectively, and a detector 5 that performs detection of each of the amplified output signals.
1 and 52, and voltage fluctuation detection circuits 61 and 62 that detect the approaching state of an object by looking at the falling state of the detected voltage signal, and detect if there is a voltage drop that exceeds a preset condition, The alarm device 1
The alarm canceling circuit 13 provides an alarm canceling command to the gate circuit 9 in accordance with the combination of detection output signals of the respective voltage fluctuation detection circuits 61 and 62. Note that the alarm release circuit 13 is set in response to an AND processing signal of the output signal of the voltage fluctuation detection circuit 61 and the negative output signal of the voltage fluctuation detection circuit 62, and It consists of a flip-flop FF that is reset in response to an AND processing signal with the negative output signal of the circuit 62,
The set output Q signal of the flip-flop FF is given to the gate circuit 9 as an alarm cancellation command.

However, in the case of the device configured in this way, when a high frequency signal with a constant frequency is given from the oscillator 2 to each network 31, 32,
High-frequency output voltages that are appropriately attenuated in proportion to the proximity of objects facing the sensors 11 and 12, respectively, are sent to bandpass filter amplifiers 41 and 42, where noises induced in the sensors 11 and 12 are removed. Then, only the high frequency component of the frequency Fo is amplified. The predetermined amplified frequency signals are detected by detectors 51 and 52, respectively, and DC voltage signals corresponding to the amplitudes of the input frequency signals are sent to voltage fluctuation detection circuits 61 and 62. The voltage fluctuation detection circuits 61 and 62 each detect a falling state of the applied DC voltage signal, and detect the approaching state of an object when the degree of voltage drop becomes less than a preset reference value. , and give their respective detection outputs to the AND circuit 7. The AND circuit 7 alerts the driver 8 that the object is approaching within a certain range on the condition that the voltage fluctuation detection circuits 61 and 62 detect the approaching state of the object and the respective detection outputs are at a high level. Give instructions. As a result, the alarm device 10 issues a warning that the obstacle has entered the dangerous area by sounding or turning on the alarm. At this time, the gate circuit 9 is in an open state for transmitting the drive signal output from the driver 8 to the alarm 10. In this case, each sensor 1
A case is assumed in which the approach state of an object O1 that is approximately equidistant from objects 1 and 12 is detected. At this time, when the object O2 approaches each sensor 11, 12, the voltage fluctuation detection circuit 61 on the sensor 11 side detects the approaching state of the object O2 and its detection output becomes high level. However, in the case of the voltage fluctuation detection circuit 62 on the sensor 12 side, the degree of fall in the input voltage does not fall below the reference value and the approaching state of the object O2 is not detected, so the detection output is at a low level. Therefore, the AND circuit 7 does not issue any warning command to the driver 8.

In addition, in the relationship shown in Figure 3, when an object O2, for example, a raindrop on the body of a car, which is initially in a direction other than the detection target, falls and later moves to a predetermined direction, which is indicated by O1 in the diagram, and becomes the detection target. In that case, in the initial state, the output signal of the voltage fluctuation detection circuit 61 on the sensor 11 side is high level, and the sensor 12
The output signal of the voltage fluctuation detection circuit 62 on the side becomes low level, and the flip-flop FF of the alarm canceling circuit 13 is set, and the set output Q signal is given to the gate circuit 10 as an alarm canceling command to forcibly close the gate. or break it off. Thereafter, with a time difference, the output signals of the voltage fluctuation detection circuits 61 and 62 on both the sensors 11 and 12 sides both become high level, and an alarm command is issued from the AND circuit 7, but at that time the gate circuit 9 has already been activated. Since the alarm 10 is disconnected, the alarm 10 will not operate, and therefore no false alarm will be issued due to object detection. Further, when an object is no longer detected by either of the sensors 11 and 12, the flip-flop FF is reset, thereby returning the gate circuit 9 to its original gate open state.

FIG. 4 shows a specific example of the configuration of the voltage fluctuation circuit 6 (61, 62), in which the detector 5 (51, 5
2) A first amplifier AMP that amplifies the output voltage Vo
1, a second amplifier AMP2 that similarly amplifies the output voltage Vo with a certain delay element, a comparator COMP that compares the amplified output voltages V1 and V2, respectively, and the time width of the comparison output signal S. and a determination circuit DEC that determines whether or not the duration exceeds a preset time width. In addition, the amplifier
AMP1 and AMP2 are set so that their respective gains are the same. Also, the comparator COMP is V
The offset voltage is adjusted so that a low level output is produced when 1≧V2, and a high level output is produced when V1<V2.

With this configuration, as shown in FIG. 5, when the input voltage Vo falls over a period of T,
The output voltage V1 of the amplifier AMP1 falls in the same period T, but the output voltage V2 of the amplifier ANP2 falls with a certain delay Td, and as a result, the period T+Td becomes V1<V2, and the comparator
The output S of COMP becomes high level. However,
The falling time T of the input voltage Vo is determined by each sensor 11, 12.
Since it changes depending on the object's proximity to the object, when the time width of the comparison output S exceeds a predetermined value, the judgment circuit DEC determines that the object is approaching within a certain range and issues an alarm to the driver 8. Try to give commands. In addition, each sensor 11, 12
When the input voltage Vo becomes constant without changing the position of the object, V1=V2, and when the object moves away from each sensor 11, 12, V1>V2 and the output of the comparator COMP becomes low. level, and no alarm command is issued at that time.

FIG. 6 shows an example of application in which the object detection device according to the present invention is used to detect obstacles when a car is running. Sensors 11 and 12 are installed in parallel on the front of section 15 as shown in the figure, detecting only the obstacle in front and giving a warning to the driver when the obstacle enters the dangerous area. This makes it possible to effectively prevent false alarms from occurring due to external disturbances, such as raindrops accumulated on the upper side of the bumper 15 or unevenness of the road surface. In this case, especially when raindrops that have accumulated on the body of the automobile 14 or the upper side of the bumper 15 have fallen and are detected by the sensors 11 and 12, the alarm is canceled as described above, and a false alarm due to obstacle detection is caused. It will no longer be served.

FIG. 7 shows another example of application, in which obstacles on both sides of the front of the vehicle 14 can be detected well, and a pair of sensors are installed on both sides of the bumper 15. 11A, 11B
and the pair of sensors 11A, 1
A sensor 12 is provided in parallel with 1B. In this case, three object detection systems corresponding to each sensor 11A, 11B, and 12 are required, and the voltage fluctuation detection circuit 6 (61A,
61B, 62), as shown in FIG.
After processing each output signal of the voltage fluctuation detection circuits 61A and 61B corresponding to the above by the OR circuit 16,
The OR processing signal and the output signal of the voltage fluctuation detection circuit 62 corresponding to the sensor 12 are processed by the AND circuit 7, and the driver 8
The alarm device 10 may be driven as appropriate via the.

Effects As described above, in the object detection device according to the present invention,
Means for replacing each change in stray capacitance between at least two sensors comprising directional electrode members and an object to be detected with changes in frequency signals, and attenuation of each frequency signal. means for detecting the approaching state of an object according to the detection result, means for taking a logical product of the respective detection outputs, means for issuing an object detection alarm according to the logical product output, This sensor is configured with a means for detecting that an object is detected by the other sensor with a time difference from one sensor to the other, and canceling the alarm.With a simple configuration, it is possible to detect an object such as an object approaching in front of the vehicle. It has the advantage of being able to reliably detect objects with directionality and issue a warning, as well as eliminating false alarms caused by disturbances caused by objects other than the direction of the detection target, especially raindrops falling from the car body, etc. It has several advantages.

[Brief explanation of drawings]

FIG. 1 is a block configuration diagram showing an embodiment of an object detection device according to the present invention, FIG. 2 is a circuit configuration diagram showing the basic principle of object detection according to the present invention, and FIG.
FIG. 4 is a block diagram showing a specific configuration example of the voltage fluctuation detection circuit in the same embodiment, and FIG. 5 is a time chart of various signals in the voltage fluctuation detection circuit. , FIG. 6 and FIG. 7 are diagrams each showing a specific example of sensor installation in an automobile, and FIG. 8 is a block diagram showing an example of the configuration of a processing circuit for object detection signals by each sensor system in the case of FIG. 7. It is a diagram. 11, 12...sensor, 2...oscillator, 31,
32...Network, 41,42...Band filter amplifier, 51,52...Detector, 61,62...
Voltage fluctuation detection circuit, 7...AND circuit, 8...driver, 9...gate circuit, 10...alarm, 1
3...Alarm release circuit.

Claims (1)

[Claims] 1. Means for replacing each change in stray capacitance between at least two sensors made of directional electrode members and an object to be detected with a change in frequency signal, and attenuation of each frequency signal. means for detecting the approaching state of an object according to the detection output, means for calculating the logical product of the respective detection outputs, means for issuing an object detection alarm according to the logical product output, 1. An object detection device comprising: means for detecting that an object is detected by the other sensor with a time difference after that, and canceling the alarm.