JP2018119936A - Radar device and method of controlling radar device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To detect a target reliably even when a radio wave interference occurs.SOLUTION: Provided is a radar device, mounted in a vehicle, for detecting a target, comprising: transmission means (transmission antenna 14) for transmitting an electromagnetic wave toward a target; reception means (receiving antenna 17) for receiving the electromagnetic wave transmitted by the transmission means and reflected by a target; detection means (control-processing unit 15) for detecting a noise floor included in the signal received by the reception means; setting means (control-processing unit 15) for setting a detection threshold for detecting a target in accordance with the noise floor detected by the detection means; and adjustment means (control-processing unit 15) for making adjustment on the basis of the noise floor detected by the detection means so that the detection threshold set by the setting means becomes smaller than a detection threshold at normal time when it is determined that there is occurrence of a radio wave interference.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a radar apparatus and a radar apparatus control method.

  Patent Document 1 discloses a radar apparatus that measures a target by a spread spectrum method. The PN signal for reference is delayed in two stages by a delay device, and a coarse distance resolution and a narrow distance resolution are secured by the delay device. A technique relating to a radar apparatus that is resistant to interference and interference by controlling the VCO frequency so as to maximize the output of the comparator and obtaining the relative speed with the target is disclosed.

JP-A-5-256936

  By the way, in the technique shown in Patent Document 1, when radio wave interference from another vehicle on which a radar apparatus is mounted occurs, a target cannot be detected or a false image is detected in some cases. There is.

  The present invention has been made in view of the above situation, and an object thereof is to provide a radar apparatus and a radar apparatus control method capable of reliably detecting a target even when radio wave interference occurs.

In order to solve the above-described problems, the present invention provides a radar device that is mounted on a vehicle and detects a target, a transmission unit that transmits electromagnetic waves toward the target, and a transmission unit that transmits the electromagnetic wave toward the target. A receiving means for receiving the reflected electromagnetic wave, a detecting means for detecting a noise floor contained in a signal received by the receiving means, and the target according to the noise floor detected by the detecting means. A setting means for setting a detection threshold for detection, and the detection threshold set by the setting means when it is determined that radio wave interference has occurred based on the noise floor detected by the detection means And adjusting means for adjusting the value to be smaller than the normal detection threshold value.
According to such a configuration, the target can be reliably detected even when radio wave interference occurs.

Further, according to the present invention, when the setting means determines the value obtained by multiplying the value of the noise floor by X as the detection threshold value, and the adjustment means determines that radio wave interference is occurring, the noise floor The value is adjusted to be smaller than the normal detection threshold value by multiplying the value of Y by Y (Y <X).
According to such a configuration, the detection threshold can be appropriately set by simple calculation.

Further, the present invention is characterized in that when setting the detection threshold value, the value of the noise floor is corrected according to the temperature of the radar apparatus.
According to such a configuration, it is possible to reduce the influence of noise of the semiconductor elements included in the radar apparatus.

In the present invention, when the target being detected disappears, the adjusting means determines that radio wave interference has occurred, and the detection threshold set by the setting means is the normal value of the detection threshold. It is characterized by adjusting so that a value may become smaller than a detection threshold value.
According to such a configuration, it is possible to appropriately set the detection threshold based on the presence or absence of the disappearance of the target.

Further, according to the present invention, in a method for controlling a radar device mounted on a vehicle and detecting a target, a transmission step of transmitting an electromagnetic wave toward the target, a transmission step transmitted in the transmission step and reflected by the target In order to detect the target according to the reception step of receiving the electromagnetic wave, the detection step of detecting a noise floor included in the signal received by the reception step, and the noise floor detected in the detection step If it is determined that radio wave interference has occurred based on the setting step for setting the detection threshold value and the noise floor detected in the detection step, the detection threshold value set in the setting step is And an adjustment step for adjusting the value to be smaller than the detection threshold at the time. .
According to such a method, a target can be reliably detected even when radio wave interference occurs.

  According to the present invention, it is possible to provide a radar apparatus and a radar apparatus control method capable of reliably detecting a target even when radio wave interference occurs.

It is a figure which shows the example of mounting of the radar stem which concerns on embodiment of this invention. It is a figure which shows the structural example of the radar system which has a radar apparatus concerning embodiment of this invention. FIG. 3 is a block diagram illustrating a detailed configuration example of the radar apparatus illustrated in FIG. 2. FIG. 4 is a block diagram illustrating a detailed configuration example of a control / processing unit illustrated in FIG. 3. It is a figure for demonstrating operation | movement of embodiment shown in FIG. It is a figure for demonstrating operation | movement of a prior art example. It is a figure for demonstrating operation | movement of embodiment shown in FIG. It is a flowchart for demonstrating operation | movement of embodiment shown in FIG.

  Next, an embodiment of the present invention will be described.

(A) Description of Configuration of Embodiment FIG. 1 is a diagram illustrating an implementation example of a radar system according to an embodiment of the present invention. As shown in this figure, the radar devices 10-1 and 10-2 constituting the radar system according to the embodiment of the present invention are arranged on the left and right of the rear part of the vehicle C, respectively. These radar apparatuses 10-1 and 10-2 have a detection area behind the vehicle C, a target (for example, another vehicle, bicycle, person, etc.) as a detection target exists in the detection area, and If there is a possibility that the target will contact or collide with the host vehicle, an alarm is issued.

  FIG. 2 is a diagram illustrating a configuration example of a radar system. The radar system according to the present embodiment includes an ECU (Electric Control Unit) 30 and radar devices 10-1 and 10-2. The ECU 30 and the radar devices 10-1 and 10-2 are connected by communication lines 41 and 42. Configured.

  Here, the ECU 30 controls each part of the vehicle, detects a target based on information supplied from the radar devices 10-1 and 10-2 via the communication lines 41 and 42, and warns as necessary. Etc.

  The radar devices 10-1 and 10-2 irradiate a target as a detection target with a pulse signal, detect the target based on the reflection signal, and transmit the target to the ECU 30 via the communication lines 41 and 42. The radar apparatuses 10-1 and 10-2 are connected by communication lines 41 and 42, for example, one of which operates as a master and the other of which operates as a slave.

  FIG. 3 is a diagram illustrating a configuration example of the radar apparatuses 10-1 and 10-2 illustrated in FIG. Since the radar apparatuses 10-1 and 10-2 have the same configuration, they will be described as the radar apparatus 10 below.

  As shown in FIG. 3, the radar apparatus 10 includes a local oscillation unit 11, a transmission unit 12, a control / processing unit 15, a reception unit 16, and an A / D (Analog to Digital) conversion unit 21 as main components. Yes.

  Here, the local oscillating unit 11 generates a CW (Continuous Wave) signal having a predetermined frequency and supplies it to the transmitting unit 12 and the receiving unit 16.

  The transmission unit 12 includes a modulation unit 13 and a transmission antenna 14. The CW signal supplied from the local oscillation unit 11 is pulse-modulated by the modulation unit 13 and transmitted to the target via the transmission antenna 14.

  The modulation unit 13 of the transmission unit 12 is controlled by the control / processing unit 15 to generate a pulse signal by pulse-modulating the CW signal supplied from the local oscillation unit 11 and outputting the pulse signal. The transmission antenna 14 transmits the pulse signal supplied from the modulation unit 13 toward the target.

  The control / processing unit 15 controls the modulation unit 13, the variable gain amplification unit 19, and the antenna switching unit 18, and executes arithmetic processing on the reception data supplied from the A / D conversion unit 21. Detect the target.

  FIG. 4 is a block diagram illustrating a detailed configuration example of the control / processing unit 15 illustrated in FIG. 3. As shown in FIG. 4, the control / processing unit 15 includes a control unit 15a, a processing unit 15b, a communication unit 15c, and a setting unit 15d. Here, the control unit 15a includes, for example, a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), and the like, and each unit of the apparatus based on data stored in the ROM and the RAM. To control. The processing unit 15b is configured by, for example, a DSP (Digital Signal Processor) or the like, and executes processing on the digital signal supplied from the A / D conversion unit 21 to detect a target. The communication unit 15c exchanges information with other radar apparatuses via the communication lines 41 and 42. The setting unit 15d sets a detection threshold according to the presence or absence of radio wave interference and the like as will be described later.

  Returning to FIG. The receiving unit 16 includes a receiving antenna 17, an antenna switching unit 18, a variable gain amplifying unit 19, and a demodulating unit 20. The receiving unit 16 receives a signal transmitted from the transmitting antenna 14 and reflected by a target, and performs demodulation processing. After applying, output to the A / D converter 21.

  The reception antenna 17 of the reception unit 16 includes a plurality of antennas (for example, four antennas), receives a signal transmitted from the transmission antenna 14 and reflected by a target, and supplies the signal to the antenna switching unit 18. The antenna switching unit 18 is controlled by the control unit 15 a of the control / processing unit 15, selects any one of the reception antennas 17, and supplies the received signal to the variable gain amplification unit 19. The gain variable amplification unit 19 is controlled in gain by the control unit 15 a of the control / processing unit 15, amplifies the reception signal supplied from the antenna switching unit 18 with a predetermined gain, and outputs the amplified signal to the demodulation unit 20. The demodulator 20 demodulates the received signal supplied from the variable gain amplifier 19 using the CW signal supplied from the local oscillator 11 and outputs the demodulated signal.

  The A / D converter 21 samples the received signal supplied from the demodulator 20 at a predetermined cycle, converts it into a digital signal, and supplies the digital signal to the controller / processor 15.

(B) Description of Operation of Embodiment Next, the operation of the embodiment of the present invention will be described. Hereinafter, an outline of the operation of the embodiment of the present invention will be described with reference to FIGS. 5 to 7, and then a detailed operation will be described with reference to FIG. 8.

  FIG. 5 shows the relationship between the frequency and amplitude of the received signal obtained when the digital signal output from the A / D conversion unit 21 is processed by the control / processing unit 15. In this figure, the horizontal axis represents frequency and the vertical axis represents amplitude.

  As shown in FIG. 5, the received signal includes not only a reflected signal from the target but also unwanted reflections from the ground, vegetation, and a spread infrastructure structure, and constitutes the radar apparatus 10. This includes noise generated by active elements and the like. For this reason, in order to identify such noise and the reflected signal from the target, a detection threshold indicated by a broken line in FIG. 5 is set, and when the amplitude of the received signal exceeds the detection threshold, Detect as reflected signal.

  As a method for setting such a detection threshold, for example, an average value of noise floors (value indicated by a one-dot chain line in FIG. 5) included in the received signal is obtained, and a predetermined value ( For example, a value obtained by multiplying the value “5”) is set as a detection threshold (value indicated by a broken line in FIG. 5).

  By the way, when the detection threshold is obtained by the above method, for example, when radio wave interference from another vehicle on which the radar apparatus is mounted or radio wave interference caused by radio waves transmitted from an automatic door or the like occurs, As shown in FIG. 6, the value of the noise floor is larger than that in FIG. In such a case, if a value obtained by multiplying the average value of the noise floor by a predetermined value (for example, the value “5”) is set as a detection threshold (a value indicated by a broken line in FIG. 5), the detection threshold is In some cases, the signal becomes larger than the signal from the target. In such a case, a situation occurs in which the target cannot be detected.

  Therefore, in the present embodiment, when radio wave interference does not occur, a value obtained by multiplying the average value of the noise floor by a predetermined value (for example, the value “5”) as shown in FIG. Is the detection threshold value (value indicated by a broken line in FIG. 5), and when radio wave interference occurs, as shown in FIG. 7, normal time (when radio wave interference does not occur) with respect to the average value of the noise floor A value obtained by multiplying a smaller value (for example, the value “3”) is set as a detection threshold (value indicated by a broken line in FIG. 7). Thereby, as shown in FIG. 7, since the reflected signal from the target is equal to or greater than the detection threshold, the target can be reliably detected even when radio wave interference occurs. Note that whether or not radio wave interference has occurred can be determined, for example, when radio wave interference has occurred when the average value of the noise floor exceeds a predetermined threshold.

  Next, the detailed operation of the embodiment of the present invention will be described with reference to FIG.

  FIG. 8 is a flowchart showing an example of processing executed in the embodiment of the present invention. This process is executed, for example, when the ignition key of the vehicle is turned on and supply of power to the radar apparatuses 10-1 and 10-2 is started. When the processing of the flowchart shown in FIG. 8 is started, the following steps are executed.

  In step S10, the control unit 15a of the control / processing unit 15 detects the vehicle speed V of the host vehicle by controlling the communication unit 15c and causing the ECU 30 to make an inquiry.

  In step S11, the control unit 15a determines whether or not the vehicle speed V detected in step S10 is greater than the threshold value Th1 and less than the vehicle speed Th2 (Th2> Th1), and satisfies Th1 <V <Th2 ( In step S11: Y), the process proceeds to step S12. In other cases (step S11: N), the process proceeds to step S19. For example, in the case of RCTA (Rear Cross Traffic Alarm) that detects and alerts a target approaching from behind the vehicle when the vehicle moves backward, for example, −15 (km / h) <V <0 is satisfied. In this case, it is determined as Y and the process proceeds to step S12.

  In step S12, the control unit 15a requests the processing unit 15b to detect the average value Nf of the noise floor. As a result, the processing unit 15b detects the average value Nf of the noise floor of the received signal and notifies the control unit 15a.

  In step S13, the control unit 15a detects, for example, the temperature θ in the casing of the radar apparatus 10 by referring to the output of a thermistor or the like (not shown).

  In step S14, the control unit 15a corrects the average value Nf of the noise floor detected in step S12 by the temperature θ detected in step S13. More specifically, the noise floor includes noise generated by active elements (for example, transistors) included in the radar apparatus 10. Noise (for example, thermal noise) generated by such an active element increases as the temperature increases, and such noise is independent of radio wave interference. Therefore, in order to clarify the contribution of the radio wave interference to the noise floor, a process of correcting the average value of the noise floor according to the temperature θ is executed. For example, a predetermined value according to the temperature θ (for example, a value of a function f (θ) that increases as the value of the temperature θ increases) is subtracted from the average value Nf of the noise floor.

  In step S15, the control unit 15a compares the noise floor average value Nf corrected by the temperature θ in step S14 with the threshold Th3. If Nf> Th3 (step S15: Y), the control unit 15a proceeds to step S16. In other cases (step S15: N), the process proceeds to step S17. Note that the threshold value Th3 can be obtained by actual measurement in a state where the threshold Th3 is mounted on the vehicle.

  In step S16, the control unit 15a substitutes a value obtained by multiplying the average value Nf of the noise floor subjected to temperature correction in step S14 by the value “3” for the detection threshold Thd. Needless to say, the value “3” is an example, and other values may be used.

  In step S17, the control unit 15a substitutes a value obtained by multiplying the average value Nf of the noise floor subjected to temperature correction in step S14 by the value “5” for the detection threshold Thd. Needless to say, the value “5” is an example, and other values may be used.

  In step S18, the processing unit 15b executes a process of detecting the target using the detection threshold Thd set in step S16 or step S17.

  More specifically, the signal supplied from the local oscillating unit 11 is converted into a pulse signal based on the set repetition period by the modulating unit 13 and transmitted via the transmitting antenna 14. The pulse signal reflected by the target is received by the receiving antenna 17. For example, the receiving antenna 17 includes four antennas, and the antenna switching unit 18 switches and inputs the signals Rx1 to Rx4 shown in FIG. The variable gain amplification unit 19 amplifies the signal supplied from the antenna switching unit 18 and supplies the amplified signal to the demodulation unit 20. The demodulator 20 demodulates the signal supplied from the variable gain amplifier 19 using the CW signal supplied from the local oscillator 11 and supplies the demodulated signal to the A / D converter 21. The processing unit 15b of the control / processing unit 15 performs processing on the digital signal supplied from the A / D conversion unit 21 and performs processing of detecting a target using the detection threshold Thd described above.

  As a result, when there is no radio wave interference, as shown in FIG. 5, a detection threshold value Thd for discriminating between the noise floor and the target is set, and as shown in FIG. When the average value of the noise floor rises, the value of the detection threshold Thd is set small, so that the detection threshold Thd is larger than the amplitude of the reflected signal from the target as shown in FIG. The situation where the target cannot be detected can be avoided.

  In step S19, the control unit 15a determines whether or not to end the process. If it is determined not to end the process (step S19: N), the control unit 15a returns to step S10 to repeat the process, and otherwise (step S19). : Y) ends the process.

  According to the above processing, the operation of the above-described embodiment can be realized.

(C) Description of Modified Embodiment It goes without saying that the above embodiment is merely an example, and the present invention is not limited to the case described above. For example, in the above embodiment, the above processing is executed in each of the radar devices 10-1 and 10-2, but the floor noise detected by each of the radar devices 10-1 and 10-2 is detected. You may make it perform the above-mentioned process based on an average value. According to such processing, since it is based on the average value of the two radar apparatuses 10-1 and 10-2, a more accurate floor noise value can be obtained. Or you may make it perform the above-mentioned process based on the difference value of the floor noise of the two radar apparatuses 10-1 and 10-2. According to such a process, for example, when another vehicle approaches from an obliquely rearward direction, an accurate floor noise value can be obtained.

  Also, the average value of floor noise in the past is stored, and the average value of floor noise at that time is compared with the average value of floor noise in the past, so that the approach of other vehicles equipped with radar devices can be reduced. You may make it detect.

  In the above embodiment, when the average value Nf of the noise floor exceeds the threshold value Th3, the detection threshold value is immediately changed. However, a state in which the average value Nf of the noise floor exceeds the threshold value Th3 is predetermined. The detection threshold may be changed when the time or a predetermined number of times continues.

  Also, if the target that has been detected until then suddenly stops being detected, it is determined that the interference is caused by radio interference, the detection threshold is changed to a smaller value, and if the target is detected again, The detection threshold value may be used until the target disappears from the detection area.

  Further, the processing of the flowchart shown in FIG. 8 is an example, and it goes without saying that the present invention is not limited to the processing of these flowcharts. For example, the average value Nf of the noise floor is multiplied by the value “3” in step S16, and the average value Nf of the noise floor is multiplied by the value “5” in step S17. If the value multiplied in step S17 is X, Y <X may be set.

10-1, 10-2 Radar device 11 Local oscillator 12 Transmitter 13 Modulator 14 Transmitting antenna (transmitting means)
15 Control / Processing Unit 15a Control Unit (Setting Unit, Adjustment Unit)
15b Processing unit (detection means)
15c communication unit 15d setting unit 16 receiving unit 17 receiving antenna (receiving means)
Reference Signs List 18 antenna switching unit 19 variable gain amplification unit 20 demodulation unit 21 A / D conversion unit 30 ECU
41, 42 Communication line

Claims (5)

In a radar device that is mounted on a vehicle and detects a target,
Transmitting means for transmitting electromagnetic waves toward the target;
Receiving means for receiving the electromagnetic wave transmitted by the transmitting means and reflected by the target;
Detecting means for detecting a noise floor included in a signal received by the receiving means;
Setting means for setting a detection threshold for detecting the target according to the noise floor detected by the detection means;
When it is determined that radio wave interference has occurred based on the noise floor detected by the detection means, the detection threshold set by the setting means is smaller than the normal detection threshold. Adjusting means for adjusting so that
A radar apparatus comprising: The setting means sets the value obtained by multiplying the noise floor value by X as the detection threshold,
When it is determined that radio wave interference has occurred, the adjustment unit adjusts the noise floor value to be smaller than the normal detection threshold value by multiplying the noise floor value by Y (Y <X). ,
The radar apparatus according to claim 1.   The radar apparatus according to claim 1, wherein when setting the detection threshold, the value of the noise floor is corrected according to a temperature of the radar apparatus.   When the target being detected disappears, the adjustment unit determines that radio wave interference has occurred, and the detection threshold set by the setting unit is greater than the detection threshold during normal time. The radar apparatus according to claim 1, wherein the radar apparatus is adjusted to be small. In a control method of a radar device mounted on a vehicle and detecting a target,
A transmission step of transmitting electromagnetic waves toward the target;
A reception step of receiving the electromagnetic wave transmitted in the transmission step and reflected by the target;
A detection step of detecting a noise floor included in the signal received by the reception step;
A setting step for setting a detection threshold for detecting the target according to the noise floor detected in the detection step;
If it is determined that radio wave interference has occurred based on the noise floor detected in the detection step, the detection threshold set in the setting step is smaller than the normal detection threshold. An adjustment step to adjust so that
A method for controlling a radar apparatus, comprising:

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