JPH0659032A - Automobile collision prevention radar - Google Patents

Abstract

PURPOSE:To obtain accurate relative distance and relative speed irrespective of the environment conditions for use by making control in such a way that the output signal electric power value of a mixer agrees with signal electric power data. CONSTITUTION:A comparator circuit 12 has a storage means which stores relative distance data and signal electric power data which are related each other. The circuit 12 outputs a control signal Sc by comparing electric power value of a signal S6 to be outputted from a mixer 7 and relative distance information D1 to be output from a signal processing circuit 9 with relative distance data and signal electric power data. Data to be stored in the storage means is obtained from a signal which is received under the environment conditions at normal temperature and not in raining and snowing condition. As the result of this comparison, when electric power value of the signal S6 is larger than the signal electric power data, the signal Sc which reduces gain of an automatic gain control amplifier 11 is outputted. On the other hand, when electric power value of the signal S6 is small, the signal Sc which increases the gain of the amplifier 11 is outputted. Accordingly, electric power value of the signal S6 to be outputted from the mixer 7 is controlled at a constant value in accordance with relative distance by the signal Sc.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a vehicle collision prevention radar. At present, there is an automobile collision prevention radar that uses a laser beam, but it has a drawback that it is weak against fog and rain in principle.

Therefore, an automobile collision prevention radar using radio waves in a high frequency band such as a millimeter wave has been developed and is about to be realized in the near future. This car collision prevention radar, which is being developed, calculates the relative distance and relative speed to the vehicle in front and obstacles, and warns the driver when it is dangerous, and performs driving control based on the relative distance and relative speed. It is something that

However, depending on the environment of use, the output power of the radar must be increased, so that the amplifier on the receiving side may perform a non-linear operation, and accurate relative distance and relative speed may not be obtained. There is a demand for a radar that can detect relative distance and relative velocity.

[0004]

2. Description of the Related Art A block diagram of a conventional automobile collision prevention radar is shown in FIG.

The automobile collision prevention radar shown in FIG. 5 includes an oscillator 1, a transmission side amplifier 2, a hybrid circuit 3, transmission / reception antennas 4 and 5, a reception side amplifier 6, and a mixer 7.
And a baseband circuit 8 and a signal processing circuit 9 having a built-in MPU.

The oscillator 1 outputs a signal S2 having a frequency corresponding to the setting signal S1. However, the setting signal S1
Is a triangular wave of a predetermined frequency (for example, 750 Hz), and the frequency of the signal S2 output from the oscillator 1 is changed by changing the level of this triangular wave.

The signal S2 is amplified by the amplifier 2, this amplified signal S3 is branched by the hybrid circuit 4, and one signal S3 is output from the antenna 4 as a radio wave M1 in front of the vehicle on which this radar is mounted. .

The output radio wave M1 is reflected by, for example, another vehicle traveling ahead (not shown) and returned as a reflected wave M2. The reflected wave M2 is received by the antenna 5, and the received signal S4 is amplified by the amplifier 6.

The amplified signal S5 and the other signal S3 'output from the hybrid circuit 3 are mixed by the mixer 7 and output as a signal S6. The signal S6 is converted into a signal S7 that can be processed by the baseband circuit 8 and is input to the signal processing circuit 9.

Since the signal S7 is a mixed signal of the Doppler frequency component due to the reflected wave M2 and the frequency component output from the amplifier 2, the signal processing circuit 9 detects the frequency component to calculate the signal S7. It is possible to detect and output the relative speed and the relative distance between the vehicle and another vehicle.

That is, the relative distance information D from the signal processing circuit 9
1 and the relative speed information D2 are output. By displaying the relative distance and the relative speed based on the relative distance information D1 and the relative speed information D2, the driver can be notified of the relative distance and the relative speed, and an alarm can be issued to the driver when it is dangerous.

[0012]

By the way, in the above-described automobile collision prevention radar, the transmission power and the reception gain change depending on the temperature, and there is a difference in propagation loss between fine weather and too heavy rain or snow. The sensing distance changes.
For example, the detection distance up to 100 m can only be detected up to 80 m.

In order to prevent such a situation, there is a measure that the output power is normally raised and a signal over a certain distance is cut by the signal processing circuit 9, which is a measure of the own vehicle. It is easy to pick up an erroneous signal unrelated to the traveling direction, or the receiving side amplifier 6 or the baseband circuit 8 performs a non-linear operation due to an unnecessarily large received signal reflected from an obstacle in a short distance. S / N depending on the operation
Since the ratio deteriorates, there is a problem that proper relative distance and relative speed cannot be obtained.

Further, if the output power is constantly increased and used, the power consumption increases correspondingly, and each device becomes in a high temperature state, so that there is a problem that deterioration is accelerated. The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an automobile collision prevention radar that can obtain an accurate relative distance and relative speed regardless of the use environment conditions.

[0015]

According to the vehicle collision prevention radar of the first principle of the present invention, a high frequency signal output from the oscillator of the radar mounted on the vehicle is amplified by the transmission side amplifier and then passed through the branching means. Output from the antenna to another vehicle or obstacle in front, the reflected wave is received by the antenna and amplified by the receiving side amplifier, and this amplified signal and the other high frequency signal branched by the branching means are mixed by the mixer. Then, the mixed signal is converted into a predetermined frequency, and the converted frequency component is detected by the signal processing means to detect the relative distance and relative distance information between the own vehicle and another vehicle or an obstacle. In an automobile collision prevention radar that is useful for preventing collisions, a plurality of relative distance data at predetermined distance intervals and a storage unit storing signal power data associated with each of the plurality of relative distance data are stored, The relative distance data corresponding to the distance information is searched, the signal power data associated with the searched relative distance data is compared with the output signal power value of the mixer, and the gain of the receiving side amplifier is determined according to the comparison result. By varying, the output signal power value of the mixer is controlled so that the output signal power value substantially matches the signal power data.

The second principle has a storage means for storing a plurality of relative distance data at predetermined distance intervals and signal power data associated with each of the plurality of relative distance data, and corresponds to the relative distance information. By searching the relative distance data, comparing the signal power data associated with the searched relative distance data and the output signal power value of the mixer, by varying the gain of the transmitter amplifier according to the comparison result, It is configured by providing means for controlling so that the output signal power value of the mixer substantially matches the signal power data.

The third principle is to detect the amount of rainfall, and a control signal output according to the detected amount of rainfall so that the output signal power value of the mixer becomes substantially constant. It is configured by providing a means for controlling the gain.

[0018]

According to the radar of the first principle of the present invention described above,
The detected relative distance information is compared with the relative distance data and the signal power data that are stored in advance in association with each other, the relative distance data corresponding to the relative distance information is searched, and the relative distance data is associated with the searched relative distance data. The signal power data and the output signal power value of the mixer are compared, and the gain of the receiving side amplifier is changed according to the comparison result, so that the output signal power value of the mixer almost matches the signal power data. Since it is controlled, the mixer always outputs a signal of a constant power value regardless of changes in environmental conditions such as temperature, rain, or snow.

Therefore, unlike the prior art, it is not necessary to increase the normal output power in consideration of environmental conditions, which makes it easier to pick up an erroneous signal unrelated to the traveling direction of the vehicle, or An unnecessarily large received signal reflected from an obstacle in the distance causes the receiving side amplifier, baseband circuit, etc. to perform non-linear operation, and the S / N ratio deteriorates due to this non-linear operation. The distance and the relative speed are not lost.

Further, since it is not necessary to constantly increase the output power, it is possible to reduce the power consumption as compared with the prior art, and since each device does not reach a high temperature state, the deterioration thereof can be reduced as compared with the prior art. Further, it is possible to secure a detection distance (for example, 100 m) having a predetermined ability regardless of environmental conditions.

According to the second principle, the relative distance data corresponding to the relative distance information is retrieved, the signal power data associated with the retrieved relative distance data and the output signal power value of the mixer are compared, and By varying the gain of the transmission-side amplifier according to the comparison result, the output signal power value of the mixer is controlled so as to substantially match the signal power data, and the same effect as the first principle can be obtained.

According to the third principle, the amount of rainfall is detected at the time of rainfall, and the control signal output according to the detected amount of rainfall causes the output signal power value of the mixer to be substantially constant, or Since the gain of the receiving side amplifier is controlled, it is possible to secure a detection distance of a predetermined ability regardless of environmental conditions such as heavy rain.

[0023]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram of a vehicle collision prevention radar according to a first embodiment of the present invention. In this figure, parts corresponding to the parts of the conventional example shown in FIG. 5 are assigned the same reference numerals and explanations thereof are omitted.

In FIG. 1, 11 is an automatic gain control amplifier, and 12 is a comparison circuit. Automatic gain control amplifier 11
Is for amplifying the received signal S4 with a gain that changes according to the control signal Sc output from the comparison circuit 12.

The comparison circuit 12 has a storage means for storing the relative distance data and the signal power data which are related to each other, and the power value of the signal S6 output from the mixer 7 and the signal processing circuit 9. Relative distance information D output from
The control signal Sc is output by comparing 1 with the relative distance data and the relative distance data.

The relative distance data and the signal power data stored in the storage means are obtained, for example, from signals received under environmental conditions at room temperature, not under rain or snow.

In the case of no rain or snow and normal temperature, the electric power of the transmitted / received radio waves M1 and M2 does not become too large due to the low temperature, and the propagation loss does not become large and attenuate due to the rain, so that the signal Accurate relative distance information D1 can be obtained from the processing circuit 9.

At this time, the signal S6 output from the mixer 7
The electric power value of 1 is associated with the relative distance information D1 and is stored in the storage means as each data. Since the power value of the signal S6 and the relative distance information D1 differ depending on the distance to the vehicle ahead, the power value of the received signal S6 and the relative distance information D1 obtained at a predetermined distance interval are stored as data. Signal S
The power value of 6 increases when the relative distance is short.

In the comparison in the comparison circuit 12, the relative distance data in the storage means corresponding to the relative distance information D1 output from the signal processing circuit 9 is searched, and the signal power data and the mixer 7 related to the searched data. The power value of the received signal S6 output from is compared.

As a result of this comparison, if the power value of the received signal S6 is larger than the signal power data, the power of the received radio wave M2 is high due to a condition such as low temperature. Therefore, in this case, the gain of the automatic gain control amplifier 11 is increased. The lowering control signal Sc is output.

The received signal S4 is amplified by the amplifier 11 having the gain lowered by the control signal Sc, so that the power value of the signal S6 output from the mixer 7 becomes substantially the same as the signal power data.

On the other hand, as a result of the above comparison, if the power value of the signal S6 is smaller than the signal power data, the power of the received radio wave M2 is low due to the conditions such as rain or snow, and in this case, the automatic gain control amplifier. A control signal Sc for increasing the gain of 11 is output.

The received signal S4 is amplified by the amplifier 11 having the gain increased by the control signal Sc, so that the power value of the signal S6 output from the mixer 7 becomes substantially the same as the signal power data.

Therefore, the power value of the signal S6 output from the mixer 7 is controlled to be substantially constant according to the relative distance by the control signal Sc. In the vehicle collision prevention radar described above, the power value of the signal S6 output from the mixer 7 can be controlled to be substantially constant according to the relative distance regardless of changes in environmental conditions. , It is not necessary to increase the normal output power, which makes it easier to pick up false signals that are unrelated to the driving direction of the vehicle, or due to received signals larger than necessary reflected from obstacles in a short distance, Since the receiver-side amplifier 6, the baseband circuit 8 and the like perform a non-linear operation, and the S / N ratio deteriorates due to the non-linear operation, there is no problem that an appropriate relative distance and relative speed cannot be obtained.

Further, since it is not necessary to constantly increase the output power, it is possible to reduce the power consumption as compared with the prior art, and since each device does not reach a high temperature state, the deterioration thereof can be reduced as compared with the prior art.

Further, it is possible to secure a detection distance of a predetermined ability regardless of environmental conditions. For example, 100m in fine weather
The maximum possible detection distance is 80 m in the case of heavy rain.

Next, an automobile collision prevention radar according to the second embodiment will be described with reference to FIG. In FIG. 2, FIG.
The same reference numerals are given to the portions corresponding to the respective portions of the first embodiment shown in, and the description thereof will be omitted. However, the transmission side amplifier 6 shown in FIG. 2 is the same as that shown in FIG.

In FIG. 2, reference numeral 13 denotes an automatic gain control amplifier, which amplifies the transmission signal S2 with a gain that changes according to the control signal Sc output from the comparison circuit 12 described in the first embodiment.

That is, the relative distance data in the storage means of the comparison circuit 12 corresponding to the relative distance information D1 output from the signal processing circuit 9 is searched, and the signal power data related to the searched data and the mixer 7 are searched. The comparison circuit 12 compares the output power value of the received signal S6.

As a result of this comparison, if the power value of the received signal S6 is larger than the signal power data, it means that the transmission signal power is high due to a condition such as low temperature.
The gain of the automatic gain control amplifier 13 is reduced by the control signal Sc output from the amplifier 2, and the transmission signal S2 output from the oscillator 1 is amplified by this reduced gain, so that the power of the transmission radio wave M1 is increased. As a result, the power value of the signal S6 output from the mixer 7 becomes substantially the same as the signal power data.

On the other hand, as a result of the above comparison, if the power value of the signal S6 is smaller than the signal power data, the power of the received radio wave M2 is low due to the conditions such as rain or snow, so the control signal Sc causes the automatic gain. Control amplifier 13
Is increased, and the transmission signal S2 output from the oscillator 1 is amplified by the increased gain, so that the electric power of the transmission radio wave M1 is reduced, and as a result, the reception signal S6 output from the mixer 7 is reduced. The power value of is almost the same as the signal power data.

Therefore, the power value of the signal S6 output from the mixer 7 is controlled by the control signal Sc to be constant according to the relative distance. Also in the second embodiment, the same effect as in the first embodiment can be obtained.

Next, a third embodiment will be described with reference to FIG. In FIG. 3, parts corresponding to the respective parts of the first embodiment shown in FIG. 1 are designated by the same reference numerals, and description thereof will be omitted.
In FIG. 3, reference numeral 14 is a rainfall sensor that detects rainfall, which is an existing sensor. The rainfall sensor 14 outputs a control signal Sc1 according to the detected rainfall amount to control the gain of the automatic gain control amplifier 11 so that the signal S6 output from the mixer 7 becomes substantially constant at a predetermined power value. To do. However, the predetermined power value of the signal S6 is
It is assumed that the signal processing circuit 9 can obtain a detection distance similar to that in fine weather.

That is, as the amount of rainfall increases, the electric power of the transmitted / received radio waves is attenuated and the electric power of the signal S6 output from the mixer 7 decreases. Therefore, in order to compensate for this, the gain of the automatic gain control amplifier 11 is increased. Control is performed.

According to the vehicle collision prevention radar of the third embodiment, when it is raining, particularly when it is raining heavily, the power value of the signal S6 output from the mixer 7 is used in the signal processing circuit 9 during fine weather. It can be set to a value with which a detection distance similar to can be obtained.

That is, as in the conventional case, for example, when the weather is fine, 1
The detection distance that can be up to 00 m will not be 80 m in the case of heavy rain. Next, a fourth embodiment will be described with reference to FIG. 4, parts corresponding to the respective parts of the first embodiment shown in FIG. 3 are designated by the same reference numerals, and the description thereof will be omitted. However, the transmission side amplifier 6 shown in FIG.
The same as that shown in.

In the fourth embodiment, the control signal Sc1 output from the rainfall sensor 14 described in the third embodiment.
Thus, the gain of the automatic gain control amplifier 13 is controlled so that the signal S6 output from the mixer 7 becomes substantially constant at a predetermined power value.

That is, since the electric power of the transmitted and received radio waves is attenuated as the amount of rainfall increases, the gain of the automatic gain control amplifier 13 for increasing the electric power of the transmission signal is controlled accordingly. Also in the fourth embodiment, the same effect as in the third embodiment can be obtained.

[0049]

As described above, according to the vehicle collision prevention radar of the present invention, there is an effect that an accurate relative distance and relative speed can be obtained irrespective of the operating environment conditions.

Further, since it is not necessary to constantly increase the output power, there is an effect that the power consumption can be reduced as compared with the conventional one, and since each device does not reach a high temperature state, the deterioration thereof is less than the conventional one. There is an effect that can.

Further, there is an effect that a detection distance of a predetermined ability can be secured regardless of environmental conditions (particularly weather conditions).

[Brief description of drawings]

FIG. 1 is a block diagram of a vehicle collision prevention radar according to a first embodiment of the present invention.

FIG. 2 is a block diagram of a vehicle collision prevention radar according to a second embodiment of the present invention.

FIG. 3 is a block diagram of a vehicle collision prevention radar according to a third embodiment of the present invention.

FIG. 4 is a block diagram of an automobile collision prevention radar according to a fourth embodiment of the present invention.

FIG. 5 is a block diagram of a conventional vehicle collision prevention radar.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 oscillator 13 transmission side amplifier 3 hybrid circuit 4,5 antenna 11 reception side amplifier 12 comparison circuit (means for making gain of transmission side amplifier or reception side amplifier constant) 14 rain sensor (gain of transmission side amplifier or reception side amplifier) To keep constant)

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Shigeru Okawa 1-2-25, 1-chome, Aoba-ku, Sendai City, Miyagi Prefecture Fujitsu Tohoku Digital Technology Co., Ltd.

Claims (3)

[Claims] 1. A high frequency signal output from an oscillator of a radar mounted on a vehicle is amplified by a transmission side amplifier, and then output from an antenna to another vehicle or an obstacle in front through a branching unit, and a reflected wave thereof is output. Is received by the antenna and amplified by the receiving side amplifier, the amplified signal and the other high frequency signal branched by the branching means are mixed by a mixer, and the mixed signal is detected by the signal processing means. , A car collision prevention radar that detects the relative distance between the own vehicle and other vehicles and obstacles and assists in collision prevention by detecting relative distance information, and a plurality of relative distance data at predetermined distance intervals, and for each of these plurality of relative distance data The storage unit stores the associated signal power data, searches the relative distance data corresponding to the relative distance information, and outputs the signal power data associated with the searched relative distance data. By comparing the output signal power value data and the mixer (7), to vary the gain of the receiving amplifier (11) in accordance with the comparison result, the mixer
An automobile collision prevention radar characterized in that means (12) for controlling the output signal power value of (7) so as to substantially match the signal power data is provided. 2. A high frequency signal output from an oscillator of a radar mounted on a vehicle is amplified by a transmission side amplifier, and then output from an antenna to another vehicle or an obstacle in front through a branching means, and a reflected wave thereof is output. Is received by the antenna and amplified by the receiving side amplifier, the amplified signal and the other high frequency signal branched by the branching means are mixed by a mixer, and the mixed signal is detected by the signal processing means. , A car collision prevention radar that detects the relative distance between the own vehicle and other vehicles and obstacles and assists in collision prevention by detecting relative distance information, and a plurality of relative distance data at predetermined distance intervals, and for each of these plurality of relative distance data The storage unit stores the associated signal power data, searches the relative distance data corresponding to the relative distance information, and outputs the signal power data associated with the searched relative distance data. By comparing the output signal power value data and the mixer (7), to vary the gain of the transmission side amplifier (13) in accordance with the comparison result, the mixer
An automobile collision prevention radar characterized in that means (12) for controlling the output signal power value of (7) so as to substantially match the signal power data is provided. 3. A high-frequency signal output from an oscillator of a radar mounted on a vehicle is amplified by a transmission-side amplifier, and then output from an antenna to another vehicle or an obstacle ahead through a branching means, and a reflected wave thereof is output. Is received by the antenna and amplified by the receiving side amplifier, the amplified signal and the other high frequency signal branched by the branching means are mixed by a mixer, and the mixed signal is detected by the signal processing means. , A vehicle collision prevention radar that detects the relative distance between the own vehicle and other vehicles and obstacles to help prevent collisions, detects the amount of rainfall, and outputs the control according to the detected amount of rainfall. A means (14) for controlling the gain of either the receiving side amplifier (11) or the transmitting side amplifier (13) is provided by the signal (Sc1) so that the output signal power value of the mixer (7) becomes substantially constant. Preventing automobile collisions Over da.