JP7004520B2 - Radar device and height measurement method - Google Patents

Description

The present invention relates to a radar device that measures the height of a target using a reflected wave from the target, and a method for measuring the height thereof.

Radar devices with high weather resistance are widely used as sensors for detecting vehicles in front of automobiles such as automatic braking systems. This radar device transmits a transmitted wave (electromagnetic wave) from the transmitting antenna toward the target, receives the reflected wave reflected by the target at the receiving antenna, and targets based on the received signal output according to the intensity of the reflected wave. It is also being used as an obstacle sensor for detecting an obstacle in the vicinity when the vehicle is parked or the vehicle is started (see, for example, Patent Document 1).

By the way, it is desired to accurately detect an obstacle having a relatively low height as an obstacle around the vehicle. An obstacle with a relatively low height is, for example, a step such as a curb installed on the side of a road. A general curb has a height of about 15 cm in order to block the passage of the vehicle, and if the vehicle accidentally gets on the vehicle, the vehicle may be damaged. In addition, a notch whose height is lower than that of the curb is provided on the side of the road to allow vehicles to enter. Therefore, it is desirable that the obstacle sensor of the vehicle does not detect the step lower than the curb, but accurately detects the step higher than the curb.

To detect a curb (target) with a radar device, for example, a transmitted wave is transmitted toward the curb and reflected at the top of the curb (upper corner) and at the foot of the curb (lower recess). It is possible to calculate the height of the curb from the elevation angle by receiving the reflected wave and detecting the elevation angles of the apex and the base with respect to the receiving antenna based on the obtained received signal.

Japanese Unexamined Patent Publication No. 2015-105915

However, since the conventional radar device used as an obstacle sensor has low angular resolution, it is not possible to distinguish between the top and the base of a step of about 15 cm such as a curb. Especially for a target such as a curb, the base becomes a so-called corner reflector and a strong reflected wave is generated, and the reflected wave at the top is buried in the reflected wave at the foot. It could not be detected separately.

An object of the present invention is to provide a radar device and a height measuring method capable of accurately measuring a height even at a target having a relatively low height such as a curb in order to solve the above problems. ..

In order to solve the above problems, the radar device according to claim 1 uses a transmitting means for transmitting a transmitted wave toward the target and a plurality of receiving antennas arranged at different heights at the top and the base of the target. The receiving means that receives the reflected wave reflected by the above and outputs the received signal according to the intensity of the reflected wave, the distance of the received signal from the receiving antenna to the target, and the relative speed to the target. Based on the phase difference detected by comparing the phases of the separated signal separation means and the separated received signals, the elevation angle of either the top or the base with respect to the receiving antenna. It is characterized by comprising a height calculation means for calculating the elevation angle of the other and the other, and calculating the height of the target from the elevation angle and the distance .

In addition, claim 4 transmits a transmitted wave toward the target, receives the reflected wave reflected at the top and the base of the target by a plurality of receiving antennas arranged at different heights, and receives the reflected wave. It is a height detection method that measures the height of the target based on the received signal output according to the wave intensity, and the received signal is the distance from the receiving antenna to the target and the target. Which of the top and the base of the receiving antenna is based on the phase difference detected by comparing the phase of each of the separated signal separation steps and the separated signals with respect to the relative speed. It is characterized by comprising a height calculation step of calculating one elevation angle and the other elevation angle and calculating the height of the target from the elevation angle and the distance .

According to the first and fourth aspects of the invention, the transmitting means transmits a transmitted wave toward the target, and the receiving means receives the top of the target by means of a plurality of receiving antennas arranged at different heights. The reflected wave reflected at the foot and the foot is received, and the received signal is output according to the intensity of the reflected wave. The signal separation means and the signal separation step separate the received signal based on the distance from the receiving antenna to the target and the relative velocity to the target. In the signal extraction means and the signal extraction step, from the separated received signal, the distance to the top and the relative speed are the same for each receiving antenna, and the distance to the base is the same and the relative speed is the same. Extracts the same foot reception signal. Next, the height calculation means and the height calculation step calculate the elevation angles of the top and the base with respect to the receiving antenna based on the phase difference between the top received signals and the foot received signals, and the target height is calculated from the calculated elevation angles. Is calculated.

The second aspect of the present invention is the radar device according to the first aspect, wherein the target is a step arranged so that the top thereof extends in a substantially horizontal direction, and the transmitting means is horizontally polarized as the transmitted wave. It is characterized by sending.

3. The radar device according to claim 1 or 2, characterized in that a target detection signal is output when the height of the target is equal to or higher than a predetermined height.

According to the first and fourth aspects of the invention, the reflected signal from the target is separated based on the distance to the top and the base of the target and the relative velocity, and the separated received signal is separated by the receiving antenna. In addition, the top received signal having the same distance to the top and the same relative velocity and the foot received signal having the same distance to the base and the same relative velocity are extracted, and the top received signals and the base are extracted. Since the elevation angles of the top and base with respect to the receiving antenna are calculated based on the phase difference between the received signals, even if the height is relatively low, such as a rimstone, the top and base are calculated based on the distance to the target and the relative velocity. It is possible to accurately calculate the target height by separating the received signals of the unit.

According to the second aspect of the present invention, since the horizontally polarized wave is used as the transmitted wave, it is possible to strengthen the reflected wave from the step arranged so that the top portion extends in the substantially horizontal direction like a curb. Therefore, even if the target is a step like a curb, it is possible to detect the top of the step.

According to the third aspect of the present invention, since the target detection signal is output when the height of the target is equal to or higher than the predetermined height, the existence of the target is notified or the target is avoided based on the target detection signal. Since it can be used as a trigger to perform the action for the purpose, it is possible to avoid a collision with this target.

It is a schematic block diagram which shows the radar apparatus which concerns on embodiment of this invention. It is explanatory drawing which shows the transmission wave of the horizontal polarization with respect to a curb. It is explanatory drawing which shows the distance between the receiving antenna of FIG. 1 and a curb. It is explanatory drawing which shows the relative speed of the receiving antenna of FIG. 1 and a curb. It is a graph which shows the received signal of the reflected wave reflected by a curb. It is a graph which shows the signal which separated the received signal of FIG. 5 based on the distance to a curb. It is explanatory drawing which shows the elevation angle of the top and the foot of a curb seen from two receiving antennas. It is a graph which shows the top received signal and the foot received signal extracted from the separated received signal. It is a flowchart which shows the height measurement procedure of the target by the radar apparatus of FIG. It is a block diagram which shows the structure of the receiving part in 2 in the Embodiment which used the array antenna as a receiving antenna. It is a graph which shows the interpolation signal obtained by performing the digital beamforming process of the array antenna of FIG.

Hereinafter, the present invention will be described based on the illustrated embodiment.

[Embodiment 1]
1 to 9 show an embodiment of the present invention, and FIG. 1 is a block diagram showing a radar device 1 according to this embodiment. The radar device 1 is provided on, for example, a bumper at the front or rear of an automobile to detect obstacles in the vicinity, and more specifically, it is relatively relatively such as a wall, a fence, or a pedestrian. It has a function to accurately detect from obstacles with high height to steps such as curbs with relatively low height.

The radar device 1 is, for example, a phase monopulse type FMCW (Frequency Modulated Continuous Wave) radar that detects a target from a frequency difference between a transmitted wave and a reflected wave and measures the height thereof. The radar device 1 includes a transmitting unit (transmitting means) 2, a receiving unit (receiving means) 3, a signal processing unit (signal separating means, height calculating means and notifying means) 4, and a notifying unit 5.

The transmission unit 2 includes a modulator 21, a voltage controlled oscillator 22, and a transmission antenna 23. The modulator 21 has a function of adjusting the applied control voltage to the voltage controlled oscillator 22 to generate a triangular wave modulation signal (transmission signal) having a center frequency of 79 GHz and a frequency modulation width of 4 GHz. The transmitting antenna 23 has a function of radiating a transmitted signal as a horizontally polarized wave transmitted from the vehicle toward the front in a range of, for example, several meters to several tens of meters.

In the present embodiment, the horizontal polarization is used for the transmitted wave in order to accurately detect the top of the target curb. As shown in FIG. 2, the curb 6 has a foot portion 61 in contact with the roadway 7 on which the automobile travels, and a top portion 62 rising substantially vertically from the foot portion 61, and the base portion 61 and the top portion 62 are substantially. It is provided in parallel so as to extend in the horizontal direction. When the transmitted wave is transmitted toward such a curb 6, at the foot portion 61, the roadway 7 and the side surface of the curb 6 serve as a corner reflector and surely reflect the transmitted wave, so that a strong reflected wave can be obtained. However, since the reflecting surface of the top portion 62 has a width of less than 1 cm when viewed from the radar device 1, the reflected wave becomes weak and is buried in the reflected wave of the base portion 61. However, by using the horizontally polarized TX whose electric field component is substantially parallel to the top 62 as the transmitted wave, the intensity of the reflected wave from the top 62 is stronger than when the vertically polarized wave or the circularly polarized wave is used. It becomes possible to do.

Further, in the present embodiment, the 79 GHz band signal is used as the transmission signal in order to accurately detect the foot portion 61 and the top portion 62 of the curb 6 having a height of about 15 cm. The 79 GHz band radar is capable of wide-angle detection with higher resolution than the conventional 77 GHz band radar and 24 GHz band radar, and by selecting an appropriate frequency modulation width, it has a distance resolution of less than 4 cm and 0.1 km / h. A degree of speed resolution can be obtained. Although the case where one transmitting antenna 23 is used has been described, a plurality of transmitting antennas 23 may be provided.

The receiving unit 3 includes at least two receiving antennas 31A and 31B installed at different heights, mixers 32A and 32B connected to the receiving antennas 31A and 31B, amplification units 33A and 33B, and an A / D conversion unit 34A. , 34B and FFT circuits 35A, 35B.

In the receiving antennas 31A and 31B, for example, the receiving antenna 31A is installed at a position higher than the receiving antenna 31B, and receives the horizontally polarized reflected wave reflected by the foot portion 61 and the top portion 62 of the edge stone 6. It has a function to output a received signal according to the reception strength. A plurality of receiving antennas 31A and 31B may be installed in the horizontal direction. The mixers 32A and 32B have a function of mixing the reception signal output from the reception antennas 31A and 31B with the transmission signal input from the transmission unit 2. The amplification units 33A and 33B are amplifiers that amplify the reception signal mixed with the transmission signal. The A / D conversion units 34A and 34B have a function of converting the amplified received signal from an analog signal to a digital signal. The FFT circuits 35A and 35B have a function of performing frequency analysis processing such as a fast Fourier transform on a digital received signal to extract frequency components of the transmitted signal and the received signal.

The signal processing unit 4 includes a signal separation unit (signal separation means) 41, a signal extraction unit 42 (signal extraction means), and a height calculation unit (height calculation means) 43. The signal processing unit 4 is composed of, for example, a CPU and a memory in which a program for causing the CPU to perform a specified operation is stored. When the CPU operates according to the program, the signal separation unit 41 and the signal extraction unit 4 are configured. It functions as 42 and the height calculation unit 43.

The signal separation unit 41 uses the frequency components of the transmission signal and the reception signal extracted by the FFT circuits 35A and 35B to determine the distance and relative velocity between the reception antennas 31A and 31B and the top 62 of the edge stone 6, and the reception antenna 31A. It has a function of detecting the distance and the relative speed between the 31B and the foot 61, and separating the received signal based on the distance from the receiving antenna to the target and the relative speed with the target.

The signal extraction unit 42 has a distance from the signal separated by the signal separation unit 41 to the top reception signal having the same distance to the top 62 and the same relative speed for each of the receiving antennas 31A and 31B, and the distance to the base 61. It has a function to extract the received signal at the foot of the same and has the same relative speed.

The height calculation unit 43 detects the phase difference by comparing the top received signals of the receiving antennas 31A and 31B and the foot receiving signals, and from this phase difference, the top 62 and the foot of the two receiving antennas 31A and 31B. It has a function of calculating the elevation angle of the portion 61 and calculating the height of the curb (target) 6 from this elevation angle.

Further, the signal processing unit 4 has a function of outputting a target detection signal to the notification unit 5 when the height of the target is 15 cm or more, which is about the same as the curb 6. The notification unit 5 is, for example, a lamp or a buzzer installed in the vehicle, and when a target detection signal is input, the notification unit 5 notifies the driver that the curb 6 is present in front of the vehicle. The target detection signal may be output to an automatic braking system that automatically operates the brakes of the vehicle, and the vehicle may be automatically stopped when the target height is equal to or higher than the predetermined height. When the detection signal is output, the braking system may be controlled so that the movement of the moving vehicle in the target direction is restricted.

FIG. 3 is a schematic view showing a state in which the positional relationship between the receiving antennas 31A and 31B provided in the automobile C and the target curb 6 is viewed from the side. In this schematic diagram, the distance between the receiving antenna 31A and the receiving antenna 31B in the height direction is "d", and the height of the curb 6 from the roadway 7 to the top 62 is "h". Further, the distance from the receiving antenna 31A to the top 62 is "R1 ₁ ", the distance from the receiving antenna 31A to the base 61 is "R2 ₁ ", and the distance from the receiving antenna 31B to the top 62 is "R1 ₂ ". The distance from the receiving antenna 31B to the foot portion 61 is "R2 ₂ ". In order to measure the height of the curb 6 having a height of about 15 cm, the antenna spacing d and the distances R1 and R2 from the receiving antennas 31A and 31B to the base 61 and the top 62 are set to "d << R1, It is "R2".

Although the phase monopulse radar device cannot detect the elevation angle with one receiving antenna, FIG. 3 shows the positional relationship between the receiving antennas 31A and 31B and the curb 6 with respect to the receiving antenna 31A. The elevation angle of the top 62 is conveniently expressed as "θ _{1 1} " and the elevation angle with respect to the base 61 is "θ 2 1", the elevation angle of the top 62 with respect to the receiving antenna 31B is "θ 1 ₂ ", and the elevation angle with respect to the base 61 is "θ _{2 2} ". It is expressed as for convenience.

Further, as shown in FIG. 4, when the speed of the automobile C is V, the relative speed between the receiving antenna 31A and the top 62 becomes “Vcos θ1 ₁ ” by using the elevation angle shown for convenience above, and reception is performed. The relative velocity between the antenna 31A and the foot portion 61 is “Vcos θ2 ₁ ”. Similarly, the relative speed between the receiving antenna 31B and the top 62 is “Vcos θ1 ₂ ”, and the relative speed between the receiving antenna 31B and the base 61 is “Vcos θ2 ₂ ”.

FIG. 5 is a graph showing an example of the received signals 8 ₁ and 8 ₂ of the receiving antennas 31A and 31B. As described above, in the phase monopulse radar device, the elevation angle cannot be detected by one receiving antenna, but in order to display the received signals 8 ₁ and 82 on the graph of _FIG . 5, the receiving antenna is used. The elevation angle θ of the curb 6 with respect to 31A and 31B is used as a coordinate axis for convenience. As can be seen from this graph, the received signals 8 ₁ and 8 ₂ include a large mountain representing the reflection from the top 62 of the curb 6 and a small mountain representing the reflection from the base 61, and are in a high position. _The elevation angle of the received signal 81 of the receiving antenna 31A installed in the above is larger.

The signal separation unit 41 separates the received signals ₈₁ and 82 based on the distance to the curb ₆ and the relative speed. FIG. 6 shows a signal obtained by separating the received signal 81 based on the distance R as _an example of signal separation by the signal separation unit 41. The elevation angle θ is also used for convenience in this graph. As can be seen from this graph, when the received signal 81 is separated based on the distance R, the reflection from the _top 62 of the curb 6 appears predominantly at a short distance, and the reflection from the top 62 decreases as the distance increases. The reflection from the foot portion 61 appears predominantly. In this embodiment, a transmission signal having a center frequency of 79 GHz is used. Therefore, if the frequency modulation width is appropriately selected, the distance and relative speed to the top 62 and the distance and relative speed to the base 61 are used. Can be used to separate the received signals ₈₁ and 82 with _high resolution.

The signal extraction unit 42 sees from the two receiving antennas 31A and 31B under the condition that the elevation angle θ1 ₁ and the elevation angle θ1 ₂ with respect to the top 62 of the curb 6 are “θ1 ₁ = θ1 ₂ ”, that is, as shown in FIG. The elevation angle θ1 of the top portion 62 is determined. Further, the signal extraction unit 42 has a condition that the elevation angle θ2 ₁ and the elevation angle θ2 ₂ with respect to the base portion 61 of the curb 6 are “θ2 ₁ = θ2 ₂ ”, that is, the base portion 61 seen from the two receiving antennas 31A and 31B. The elevation angle θ2 of is determined.

Further, the signal extraction unit 42 is a _top reception signal having the same distance from the received signals 81 and 82 separated by the signal separation unit 41 based on the distance and the relative speed to the _top 62 and the same relative speed. , The foot portion reception signal having the same distance to the foot portion 61 and the same relative speed is extracted. _FIG . 8 shows _a signal extracted from the received signals 81 and 82 based on the distance and the relative velocity as an example of the extraction result of the received signal. Reference numerals 8A ₁ and 8A ₂ are top reception signals having the same distance from the reception antennas 31A and 31B to the top 62 and the same relative speed. Further, reference numerals 8B ₁ and 8B ₂ are base reception signals having the same distance from the receiving antennas 31A and 31B to the foot 61 and the same relative speed. The elevation angle θ is also used for convenience in this graph.

The height calculation unit 43 compares the phases of the top received signal 8A ₁ and the top received signal 8A ₂ , and detects the _phase difference Δφ1 represented by “d · sin θ1” in FIG. 7. This phase difference Δφ ₁ is calculated by the following mathematical formula 1. Note that "d" is the distance between the receiving antennas 31A and 31B, "θ" is the target direction (elevation angle), and "λ" is the wavelength of the received signal. Therefore, if this mathematical formula 1 is modified as in the following mathematical formula 2, the elevation angle θ1 of the top portion 62 seen from the two receiving antennas 31A and 31B can be obtained based on the _phase difference Δφ1.
Δφ ₁ = 2π × (d × sin θ1 ÷ λ) ・ ・ ・ ・ Formula 1
θ1 = sin ^-1 (Δφ ₁ × λ ÷ (2π × d)) ・ ・ ・ ・ Equation 2

Further, the height calculation unit 43 compares the phases of the foot portion reception signal 8B ₁ and the foot portion reception signal 8B ₂ , and detects the phase difference Δφ2 represented by “d · sin θ ₂ ” in FIG. 7. Next, the elevation angle θ2 of the foot portion 61 seen from the two receiving antennas 31A and 31B is calculated by using the following mathematical formula 3 in the same manner as the elevation angle θ1.
θ2 = sin ^-1 (Δφ ₂ × λ ÷ (2π × d)) ・ ・ ・ ・ Equation 3

Next, the height calculation unit 43 uses the calculated elevation angles θ1 and θ2 and the distances R1 and R2 to the top portion 62 and the base portion 61 used when extracting the signal by the signal extraction unit 42, and uses the following mathematical formulas. As shown in 4, the height h of the curb 6 is calculated.
h = R2 × sinθ2-R1 × sinθ1 ... Equation 4

Next, the operation of the above embodiment will be described with reference to the flowchart of FIG. For example, when the radar device 1 is traveling at a low speed (for example, 10 km / h or less) for parking the automobile C, the radar device 1 transmits a horizontally polarized transmission wave in the 79 GHz band from the transmission unit 2 (for example, when the vehicle C is traveling at a low speed (for example, 10 km / h or less). Step S1). The transmitted wave transmitted from the transmitting unit 2 is reflected by the target, and the reflected wave is received by the receiving unit 3 (step S2).

When the target is the curb 6, the receiving antennas 31A and 31B receive the reflected wave reflected by the base 61 and the top 62 of the curb 6 and output an analog received signal according to the intensity of the reflected wave. The received signals output from the receiving antennas 31A and 31B are mixed with the transmission signals by the mixers 32A and 32B, amplified by the amplification units 33A and 33B, and converted into digital signals by the A / D conversion units 34A and 34B. The digital received signals 8 ₁ and 8 ₂ are fast Fourier transformed by the FFT circuits 35A and 35B, and the frequency components of the transmitted signal and the received signals _{8 1} and 82 are extracted.

The signal separation unit 41 separates the received signals _{8 1} and 82 based on the distance to the curb 6 (step S3, signal separation step). Further, the signal separation unit 41 separates the received signals _{8 1} and 82 based on the relative speed with the curb 6 (step S4, signal separation step).

The signal extraction unit 42 has a distance from the received signal 81 separated based on the distance and the relative speed to the top received signal 8A ₁ having the same distance to the _top 62 and the same relative speed and the base 61. The top received signal 8B ₁ which is the same and has the same relative velocity is extracted (step S5, signal extraction step). Further, the distance from the received signal 82 separated based on the distance and the relative speed to the top received signal 8A ₂ having the same distance to the top 62 and the same relative speed and the distance to the base 61 are the same and relative to _each other. The top received signals 8B ₂ having the same speed are extracted (step S5, signal extraction step).

The height calculation unit 43 compares the top received signal 8A ₁ and the top received signal 8A ₂ to detect the phase difference _Δφ1 , and compares the foot received signal 8B ₁ with the foot received signal 8B ₂ . The _phase difference Δφ ₂ is detected, and the elevation angles θ1 and θ2 of the top 62 and the base 61 with respect to the _two receiving antennas 31A and 31B are calculated from the detected phase differences Δφ1 and Δφ2 using the above equations 2 and 3. Then, from these elevation angles θ1 and θ2, the height h of the edge stone 6 is calculated using the mathematical formula 4 (step S6, height calculation step).

When the height of the curb 6 is a predetermined height (for example, 15 cm or more) (YES in step S7), the signal processing unit 4 outputs a target detection signal to the notification unit 5 to inform the driver of the curb 6. Notify that there is (step S8).

As described above, according to the radar device 1 in which the present invention is carried out, the reflected signal from the rim stone (target) 6 is separated and separated based on the distance and the relative velocity to the top 62 and the base 61 of the rim stone 6. From the received signal, the top received signal with the same distance to the top and the same relative velocity and the base received signal with the same distance to the base and the same relative velocity are extracted for each receiving antenna. However, since the elevation angles of the apex and the foot with respect to the receiving antenna are calculated based on the phase difference between the apex received signals and the foot received signals, even if the target is a rimstone 6 having a relatively low height, the target is the target. It is possible to accurately calculate the height of the rim stone 6 by separating the received signals at the top and the base based on the distance to and the relative velocity.

In addition, since horizontal polarization is used as the transmitted wave, the reflected wave from the long portion 62 should be strengthened even if the target is a step arranged so that the top 62 extends in the substantially horizontal direction, such as a curb 6. Can be done. Therefore, even if it is a step such as a curb 6, the top portion 62 can be detected. Further, since the target detection signal is output when the height of the curb 6 is equal to or higher than the predetermined height, it is used for notification of the detection result and the like to prevent the automobile from colliding with a low step such as the curb 6. It is possible.

[Embodiment 2]
In this embodiment, the received signal of the element antenna constituting the array antenna is converted into a digital signal, and digital beamforming using the converted digital signal is performed to form a multi-beam and detect a target. The present invention is applied to a digital beamforming type radar device.

FIG. 10 shows the receiving unit 10 of the radar device of the present embodiment, and shows an array antenna 101 composed of a plurality of (for example, four) element antennas and a plurality of complex detection circuits 102 provided corresponding to each element antenna. And a Fourier conversion circuit 103. The array antenna 101 has a plurality of element antennas installed at intervals d in the vertical direction, and the antenna size from the top element antenna to the bottom element antenna is Nd. Since the height of the curb 6 having a height of about 15 cm is measured, it is desirable that the relationship between the antenna size Nd and the distance R to the curb 6 is "Nd << R".

The complex detection circuit 102 performs complex detection processing and A / D conversion of the received signals Rx ₀ , Rx ₁ , Rx ₂ , and Rx ₃ output from each element antenna, and performs complex detection signals IQ ₀ , IQ ₁ , IQ ₂ , and so on. It is output to the Fourier transform circuit 103 as IQ ₃ . The Fourier transform circuit 103 Fourier transforms each digital complex detection signal to calculate the discrete angles θ ₀ , θ ₁ , θ ₂ , and θ ₃ . As shown in FIG. 11, an interpolated signal is generated by interpolating the components of the discrete angles θ ₀ , θ ₁ , θ ₂ , and θ ₃ with a smooth function. As in the first embodiment, such an interpolated signal is separated based on the distance and relative velocity to the top 62 and the base 61 of the curb 6, and the top 62 and the base 61 are separated from the phase difference of the separated interpolated signal. The height h of the curb 6 is calculated from the calculated elevation angle and the distances to the top 62 and the foot 61.

As described above, even in the radar device using the array antenna, even if the target is a curb 6 having a relatively low height, the top is based on the distance to the target and the relative speed, as in the first embodiment. It is possible to accurately calculate the height of the curb 6 by separating the received signal at the foot and the foot. As the array antenna 101, an example in which a plurality of element antennas are arranged in the vertical direction has been described, but the element antennas may be arranged in a plurality of rows in the horizontal direction, and a larger number of antennas actually installed may be virtually arranged. A MIMO (Multi Input Multi Output) antenna that measures the orientation may be used.

Further, in the first embodiment, the received signal is separated by using both the distance and the relative speed, but the received signal may be separated by using either the distance or the relative speed, or the target is reached. Separation by distance and separation by relative velocity may be switched depending on the distance and the like. For example, when the frequency modulation width is 4 GHz with a 79 GHz band radar, the distance resolution on the order of cm cannot be obtained unless the target is approached to about 70 cm, but the relative speed is about 0.1 km / h even at a distance of 2 to 3 m. Speed resolution is obtained. Therefore, for example, the received signal may be separated by using the relative speed at a distance of about 1 to 3 m, and the received signal may be separated based on the distance at a distance of 1 m or less.

Although each embodiment of the present invention has been described in detail above, the specific configuration is not limited to this embodiment, and even if there is a design change or the like within a range that does not deviate from the gist of the present invention, the specific configuration is not limited to this embodiment. Included in this invention. For example, in the above embodiment, the FMCW radar has been described as an example, but the present invention can also be applied to a pulse radar and a pulse compression radar. Further, although a radar device functioning as an obstacle sensor of an automobile has been described as an example, for example, the radar device may be provided on a ship and used for detecting a step such as a breakwater.

1 Radar device 2 Transmitter 3 Receiver 31A, 31B Receive antenna 4 Signal processing unit (signal separation means, height calculation means, notification means)
41 Signal separation unit (signal separation means)
42 Signal extraction unit (signal extraction means)
43 Height calculation unit (height calculation means)
5 Notification unit (notification means)
6 Curb (target)
61 Foothills 62 Tops

Claims (4)

A transmission means that transmits a transmission wave toward a target,
A receiving means that receives the reflected wave reflected at the top and the base of the target by a plurality of receiving antennas arranged at different heights and outputs a received signal according to the intensity of the reflected wave.
A signal separation means for separating the received signal based on the distance from the receiving antenna to the target and the relative speed with the target.
Based on the phase difference detected by comparing the phases of the separated received signals, the elevation angle of either one of the top and the base of the receiving antenna and the elevation of the other are calculated, and the above-mentioned A height calculation means for calculating the height of the target from the elevation angle and the distance, and
A radar device characterized by being equipped with. The target is a step arranged so that the top extends substantially horizontally.
The transmitting means transmits horizontally polarized waves as the transmitted wave.
The radar device according to claim 1. A target detection signal is output when the height of the target is equal to or higher than a predetermined height.
The radar device according to claim 1 or 2. The transmitted wave is transmitted toward the target, and the reflected wave reflected at the top and the base of the target is received by a plurality of receiving antennas arranged at different heights and output according to the intensity of the reflected wave. It is a height detection method that measures the height of the target based on the received signal.
A signal separation step that separates the received signal based on the distance from the receiving antenna to the target and the relative speed to the target.
Based on the phase difference detected by comparing the phases of the separated received signals, the elevation angle of either one of the top and the base of the receiving antenna and the elevation of the other are calculated, and the above-mentioned A height calculation step for calculating the height of the target from the elevation angle and the distance, and
A height measuring method characterized by comprising.

Images