JP5511863B2 - Radar apparatus and control method thereof - Google Patents

Description

  The present invention relates to a radar device or the like that is mainly mounted on a vehicle, detects a target object such as a vehicle or a pedestrian existing around the host vehicle, and measures the position and relative speed between the host vehicle and the target object. Is.

  As a radar device installed in a vehicle, an electromagnetic wave is transmitted as a transmission signal, a reflection signal reflected by the target object is received as a reception signal, and the transmission signal and the reception signal are mixed, whereby the distance from the target object FMCW (Frequency Modulated Continuous-wave) system that obtains a beat signal proportional to the relative speed and calculates the distance and relative speed between the subject vehicle and the target object from the frequency analysis result of the beat signal and various other radar system radar devices It exists and is used in inter-vehicle distance control systems, collision avoidance and collision mitigation systems.

  In this radar device, when the received signal reflected by the target object and the electromagnetic wave (interference wave) transmitted from another radar device or communication device are received at the same time, the interference wave has the same frequency as the transmission frequency of this radar device. In such a case, noise is superimposed on the received signal, and a signal for measuring the target distance and relative speed is buried. This state is called interference. If the interference continues, normal operation of the radar apparatus cannot be expected, and a process for avoiding the interference is necessary. If interference cannot be avoided, it is necessary to notify the vehicle that interference is occurring, interrupt control until there is no interference, or notify the driver that control has been interrupted. is there.

Therefore, conventionally, for example, in Patent Document 1 below, when interference is detected, the upper limit value and the lower limit value of the transmission frequency are changed so as to avoid the frequency of electromagnetic waves from other radar devices. That is, a method for avoiding interference by changing a frequency band to be used is described.
However, when a plurality of radar apparatuses change their frequency bands in order to avoid mutual interference, there are cases in which interference occurs after the change because the frequency becomes the same.

  For this reason, in the following Patent Document 2, a radar device is provided with a communication function with other devices, a signal is sent to the other radar devices, a control center for determining priority is installed, and communication with the control center is performed. Priorities are assigned to determine which radar device changes the frequency band.

JP 2002-168947 A JP 2009-133875 A

  However, the conventional technology requires a control center to determine the priority order, and the radar device itself needs a communication function with the control center and other radar devices. This increases the size of the radar device.

  The present invention has been made to solve such a problem, and when interference with another radar apparatus occurs, a radar apparatus that determines the priority for performing the interference avoiding operation only by information obtained from the own vehicle. And its control method.

The present invention relates to a radar device that transmits a frequency-modulated modulated wave and receives a reflected wave reflected by a target object, and determines the occurrence of interference from the received wave with a transmitted wave from another radar device. In this case, the interference processing unit calculates the radar device front azimuth and performs interference avoidance in accordance with a priority condition that defines the priority of whether to execute interference avoidance with respect to the radar device front azimuth stored in the storage unit in advance. The priority condition is obtained by dividing an omnidirectional angle into a plurality of areas, and setting a priority for each of the divided areas. Divided into two regions defining priority within the azimuth angle region, and the divided regions are sequentially divided into two regions defining priority within the divided regions, and the interference Processing unit is higher Perform interference avoidance in accordance with the area, if not avoided intended to make further interference avoidance according to the priority of the lower divided region sequentially within that region, in the radar apparatus characterized by.

  In the present invention, when interference with another radar apparatus occurs, the priority for performing the interference avoidance operation can be determined only by the information obtained from the own vehicle.

It is a block diagram of the inter-vehicle distance control system using the radar apparatus by this invention. It is a figure which shows an example of the priority conditions with respect to the radar apparatus front azimuth of the radar apparatus by Embodiment 1 of this invention. It is a figure which shows the condition where the radar apparatus each mounted in two vehicles interferes. It is a figure which shows the condition where the radar apparatus each mounted in two vehicles interferes. It is a figure which shows the condition where the radar apparatus each mounted in two vehicles interferes. It is a figure which shows the condition where the radar apparatus each mounted in two vehicles in connection with the radar apparatus by Embodiment 2 of this invention interferes. It is a figure which shows the condition where the radar apparatus each mounted in two vehicles in connection with the radar apparatus by Embodiment 2 of this invention interferes. It is a figure which shows an example of the priority conditions with respect to the radar apparatus front azimuth of the radar apparatus by Embodiment 1 of this invention. It is an operation | movement flowchart of the interference avoidance process of the radar apparatus by Embodiment 1 of this invention. It is a figure for demonstrating the use frequency band of the radar apparatus by this invention. It is a figure for demonstrating operation | movement of the radar apparatus by this invention. It is a figure for demonstrating operation | movement of the radar apparatus by this invention. It is an operation | movement flowchart of the interference avoidance process of the radar apparatus by Embodiment 2 of this invention.

  First, an outline of a radar apparatus according to the present invention will be described. In order to avoid interference, the direction in which the radar device is facing is used as a method of determining the priority of the radar device whose frequency is changed. For example, as in the priority condition shown in FIG. 2, priority is high when facing the northwest-north-east-southeast area, and priority is given when facing the southeast-south-west-northwest area. Low. In order to obtain the direction in which the radar device is facing, a geomagnetic sensor or GPS (Global Positioning System) for obtaining the direction may be built in the radar device, or from a car navigation device that is widely used. By obtaining the direction of the front direction of the host vehicle through communication and adding the previously stored radar mounting angle, that is, the angle difference between the front direction of the host vehicle and the front direction of the radar unit, the direction of the front side of the radar unit can be obtained without adding a sensor. (Radar device front azimuth) can be obtained.

  As shown in FIG. 3, when vehicles with radar devices attached in front of the vehicles face each other, the radar device attached to the vehicle facing north has a higher priority, and the radar attached to the vehicle facing south. The device becomes low priority.

  Similarly, in the case of FIG. 4, when the side radar device mounted near the left side mirror of the vehicle traveling westward and the front radar device mounted in front of the vehicle traveling northward interfere, The forward radar device is higher in priority and the side radar device facing south is lower in priority.

  Similarly, when the radar apparatus is attached to the front and rear of two vehicles traveling east as shown in FIG. 5, the radar apparatus is attached to the rear of the preceding vehicle and attached to the front of the following vehicle. In some cases, the radar apparatus may interfere, but in this case, the radar apparatus facing east has a higher priority, and the radar apparatus facing west has a lower priority.

  Further, when there is a radar along the boundary between the high priority level and the low priority level shown in FIG. 2, a case where the priority level cannot be determined occurs. This is especially likely to occur when the angle range of the transmitted wave output from the radar device is wide. As shown in FIG. 6, the radar device facing slightly east from the southeast interferes with the radar device facing slightly north from the northwest. In this case, both of the priorities shown in FIG.

  Similarly, as shown in FIG. 7, when the radar apparatus facing slightly south from the southeast and the radar apparatus facing slightly west from the northwest interfere with each other, both of the priorities shown in FIG.

  In such a case, interference avoidance is performed with four types of priorities 1 to 4 as shown in FIG. In FIG. 6, the radar device facing slightly east from the southeast has priority 2, and the radar device facing slightly north from the northwest has priority 1, and the priority is determined.

  Similarly, in FIG. 7, the radar apparatus facing slightly south from the southeast has priority 3, and the radar apparatus facing slightly west from northwest has priority 4.

  As described above, in the radar apparatus of the present invention, the priority order is determined according to the direction in which the radar apparatus is facing, and the frequency band is changed when the radar apparatus front azimuth is a direction with a lower priority order. With only the information obtained from the own vehicle, it is possible to avoid reoccurrence of interference that occurs when both radar apparatuses change the frequency band.

  Hereinafter, a radar device according to the present invention will be described with reference to the drawings according to each embodiment. In each embodiment, the same or corresponding parts are denoted by the same reference numerals, and redundant description is omitted.

Embodiment 1 FIG.
1 is a configuration diagram of an inter-vehicle distance control system using a radar apparatus according to Embodiment 1 of the present invention. In FIG. 1, 1 is a radar device, 2 is a control operation including a CPU (not shown) for controlling the radar device 1 and performing signal operation processing, a memory M for storing data, programs and the like necessary for processing. 3, 3 is a VCO (Voltage Controlled Oscillator) that controls the increase and decrease of the frequency of the transmission signal in response to a command from the control calculation unit 2, and 4 is a distribution that distributes the transmission signal generated by the VCO 3 to the transmission antenna 5 and the mixer 9. 5 is a transmission antenna that radiates a transmission wave to the outside of the radar apparatus 1, 6 is a target object detected by the radar apparatus 1, and 7 is another radar apparatus that causes interference.

  Reference numeral 8 denotes a receiving antenna that receives a reflected wave reflected by the target object 6 and a transmitted wave from another radar device 7 as a received wave. 9 is a mixer that mixes the received signal received by the receiving antenna 8 with the transmission signal distributed by the distributor 4, and generates a beat signal according to the distance, speed, and direction of the target object 6, and 10 is generated by the mixer 9. An amplifier that amplifies the beat signal, 11 is a low-pass filter that removes unnecessary high-frequency components, and 12 is an A / D converter that converts the output signal of the low-pass filter 11 from an analog signal to a digital signal.

  In the control calculation unit 2, 13 is a frequency analysis unit that performs frequency analysis from the A / D conversion result of the beat signal, 14 is a target object calculation unit that calculates the distance, relative speed, and the like of the target object 6 from the frequency analysis result, 15 Performs interference detection processing from the frequency analysis unit 13 and the target object calculation unit 14, and performs interference avoidance processing when interference occurs. Reference numeral 16 denotes an inter-vehicle distance based on the processing results of the target object calculation unit 14 and the interference processing unit 15. An inter-vehicle distance control processing unit that outputs a signal necessary for distance control to another ECU, 17 is a frequency instruction unit that outputs a command signal for changing a frequency band in accordance with an instruction from the interference processing unit 15, and these are functional blocks. Is shown as

  Reference numeral 18 denotes an in-vehicle LAN that performs communication between the radar device 1 and each ECU in the vehicle, 19 denotes a user interface device that notifies the driver (vehicle passenger) of information in accordance with information from the radar device 1, and 20 denotes an inter-vehicle distance. An engine control ECU that performs engine control based on the processing result calculated by the control processing unit 16, 21 is a brake control ECU that performs brake control based on the processing result calculated by the inter-vehicle distance control processing unit 16, and 22 is a direction in front of the host vehicle. This is a car navigation device that outputs information (azimuth angle) to the radar device 1.

  Next, an outline of the operation of the inter-vehicle distance control system using this radar apparatus will be described. In accordance with the control voltage (command signal) from the control calculation unit 2, the VCO 3 increases or decreases the transmission frequency. The control voltage from the control calculation unit 2 is determined by a frequency instruction unit 17 described later. The output signal of the VCO 3 is distributed by the distributor 4 and sent to the transmission antenna 5. A transmission wave is transmitted from the transmission antenna 5 and transmitted to the outside of the radar apparatus 1. The transmitted wave is reflected by the target object 6 and the reflected wave is received by the receiving antenna 8. Further, transmission signals from other radar devices 7 are also received by the receiving antenna 8 at the same time.

  The signal received by the receiving antenna 8 and the transmission signal distributed by the distributor 4 are mixed by the mixer 9 to obtain a beat signal. The beat signal is amplified by the amplifier 10, unnecessary frequencies are removed by the low-pass filter (LPF) 11, converted from an analog signal to a digital signal by the A / D converter 12, and input to the control calculation unit 2.

  The frequency analysis unit 13 in the control calculation unit 2 performs frequency conversion processing such as fast Fourier transform (FFT) on the beat signal converted into a digital signal, and performs frequency analysis of the beat signal. The target object calculation unit 14 performs peak detection from the frequency analysis results of the beat signal when the transmission frequency is increased and the beat signal when the transmission frequency is decreased, and the sum of the peak frequency component when the transmission frequency is increased and the peak frequency component when the transmission frequency is decreased. The distance and speed of the target object are calculated from the difference. About the calculation method of distance and speed, it is described also in the said patent document 1 etc., for example, and is a known technique.

  Next, the interference processing unit 15 determines the peak detection result of the target object calculation unit 14 and the noise level of the frequency analysis result of the frequency analysis unit 13 or the target object calculation unit 14 (for example, between the amplitude of the signal and a predetermined threshold value, respectively). Determine whether interference is occurring or not). For this interference determination processing, the method described in Patent Document 1 may be used, or other methods may be used. When interference occurs (for example, when the value indicating the degree of interference such as noise level exceeds a predetermined threshold), interference avoidance processing described later is performed, and the frequency band is changed to the frequency instruction unit 17 according to the conditions. Instruct. The frequency instruction unit 17 instructed to change the frequency band adjusts the control voltage from the control calculation unit 2 so as to be in the instructed band.

  The inter-vehicle distance control processing unit 16 calculates a vehicle control signal based on the distance and speed of the target object 6 output from the target object calculation unit 14 and the speed of the host vehicle obtained via the in-vehicle LAN 18. Vehicle control information is transmitted through the in-vehicle LAN 18, the engine control ECU 20 and the brake control ECU 21 operate, and acceleration / deceleration control is performed. At this time, if interference cannot be avoided in the interference processing unit 15, the interference processing unit 15 causes the inter-vehicle distance control processing unit 16 to interrupt the inter-vehicle distance control or further informs the user that the inter-vehicle distance control has been interrupted by the user interface device 19. Notify me.

  Next, interference avoidance processing performed by the interference processing unit 15 for each measurement cycle will be described with reference to the flowchart of FIG.

  First, in step S <b> 101, the vehicle front azimuth angle is obtained from the car navigation device 22.

Next, in step 102, the radar device front azimuth is calculated by adding or subtracting the radar mounting angle stored in advance in the memory M of the control calculation unit 2 from the front azimuth of the host vehicle. Here, it is defined as follows.
Azimuth: Horizontal angle measured clockwise with north (N) of the meridian as a reference direction. Front direction of own vehicle: Direction of travel when vehicle goes straight ahead. Front direction of own vehicle: Azimuth angle of front direction of own vehicle Radar system Front direction: Transmission direction perpendicular to the signal transmission / reception surface of the radar device Radar device front azimuth: Azimuth angle of the radar device front direction Radar mounting angle: Angle between the front direction of the radar device and the front direction of the vehicle (clockwise is positive, (Counterclockwise is negative)

  Next, in step S103, interference detection processing is performed based on the frequency analysis result in the frequency analysis unit 13. Regarding the contents of the interference detection processing, there are various means such as the above-mentioned Patent Document 1, and any one or a plurality of means may be used. If there is no interference, no action is required and the process ends.

  If interference has occurred, priority is determined from the radar apparatus front azimuth in step S104. The memory M stores the priority condition for changing the frequency domain shown in FIG. 2. As shown in FIG. 2, the priority is high when the area is in the northwest-north-east-southeast direction. Priority is low when facing the west-northwest region. If the priority is high, the process ends.

  If the priority is low, in order to avoid interference in step S105, the frequency instruction unit 17 is instructed to change the frequency band so that a frequency band different from the currently used frequency band is used, and the process is terminated. Become.

  For example, in the case of a radar device that performs modulation as shown in FIG. 10, the frequency band that is actually used is ¼ of the usable frequency band, so one of the four frequency bands is used. (The number of frequency bands used is not limited to this). The frequency band that can be used for automobiles is determined in each country, and the 76-77 GHz band is a millimeter-wave frequency band that can be used in Japan, the United States, and Europe.

  If interference occurs between radar devices that perform the same interference avoidance process and the frequency band is changed without determining the priority, the frequency band is the same in the next period as shown in FIG. However, when interference occurs in the radar apparatus of the present invention, the frequency band is changed only by the radar apparatus with the lower priority as shown in FIG. 12 to avoid the interference. That is, an effective effect can be obtained as a radar apparatus system using a plurality of radar apparatuses of the present invention.

  As described above, in the radar apparatus according to Embodiment 1 of the present invention, the priority is determined from the front azimuth angle of the radar apparatus, and when interference occurs, the frequency band is changed according to the priority so that no circuit is added. Therefore, appropriate interference avoidance can be performed at low cost.

Embodiment 2. FIG.
FIG. 13 is a flowchart showing an interference detection process performed at each measurement cycle by the interference processing unit 15 of the radar apparatus according to the second embodiment of the present invention. The configuration of the inter-vehicle distance control system using the radar device according to the second embodiment of the present invention is the same as that shown in FIG.

  Next, the flowchart of FIG. 13 will be described. First, in step S201, the front azimuth angle of the host vehicle is obtained from the car navigation device 22.

  In step S202, the radar apparatus front azimuth is calculated by adding or subtracting the radar mounting angle stored in advance in the memory M of the control calculation unit 2 from the front azimuth of the host vehicle.

  In step S203, interference detection processing is performed from the frequency analysis result in the frequency analysis unit 13 and the like. The contents of the interference detection process are the same as those in the first embodiment.

  If no interference has occurred, the number of interference occurrences set, for example, in the memory M is set to 0 in step S204, and the process ends.

  If interference has occurred, first, in step S205, the number of interference occurrences is incremented by +1.

  If the number of interference occurrences is 3 or less in step S206, the process proceeds to step S208.

  If the number of interference occurrences is 4 or more (exceeding 3) in step S206, the process proceeds to step S207. Proceeding to step S207 means that interference could not be avoided even if the interference avoidance process of the radar apparatus 1 of the present invention was performed. For example, a special case is conceivable, for example, when the entire frequency band in which the frequency band of another radar apparatus can be used is used. In step S207, the vehicle distance control processing unit 16 is notified that interference cannot be avoided. When the interference avoidance is impossible, the vehicle distance control processing unit 16 stops the inter-vehicle distance control or notifies the driver that the inter-vehicle distance control is impossible through the user interface device 19.

  Next, if the number of interference occurrences is 3 or less in step S206 and the number of interferences is 2 or less in step S208, the process proceeds to step S209. If it is three times, the process proceeds to step S212.

  In step S209, if the number of times of interference is 1, the process proceeds to step S211. If the number of times of interference is 2, the process proceeds to step S210.

  8 is stored in the memory M, and it is checked in step S211 whether or not the radar apparatus front azimuth is within the range of the priorities 3 and 4. If it is within the range of the priorities 3 and 4, the frequency band of the next period is changed in step S212.

  Through the above processing, when the radar device whose priority is directed to the direction of 1 or 2 and the radar device whose priority is directed to the direction of 3 or 4 interfere, interference can be avoided.

  However, when both radar apparatuses 1 are oriented in the direction of priority 1 or 2, both the radar apparatuses 1 have not changed the frequency band, and interference also occurs in the next period. Similarly, when both radar devices 1 are oriented in the direction of priority 3 or 4, both radar devices change the frequency band, so if the changed frequency bands overlap, interference also occurs in the next period. To do. In such a case, the number of interference occurrences is 2 in the next cycle, and if the radar apparatus front azimuth is in the range of priority 2 or 4 in step S210, the frequency band is changed in the next cycle in step S212. . If the radar apparatus front azimuth is out of the range of priority order 2 or 4, that is, in the range of priority order 1 or 3, the process ends without doing anything.

  That is, the priority condition area is divided into two areas in which the omnidirectional area defines the priority order in the omnidirectional area, and the divided areas are sequentially prioritized in the divided areas. The interference processing unit 15 performs interference avoidance in accordance with the priority order of the upper area, and in the case where it is not avoided, the priority order of the lower divided areas in the area is sequentially divided. To avoid further interference.

  By the above processing, in the period following the period in which the number of interference occurrences is 2, only the radar device facing the direction of priority 2 or 4 changes the frequency band and faces the direction of priority 1 or 3. Since the radar apparatus does not change the frequency band, interference can be avoided.

  As described above, in the radar apparatus according to Embodiment 2 of the present invention, the radar apparatus front azimuth is divided into four regions, the priority is determined, and the frequency band is changed according to the priority when interference occurs. Therefore, if the interference continues even after the interference avoidance processing in the radar apparatus according to the present invention can be performed without adding a circuit, the vehicle distance control processing unit 16 can be informed that interference cannot be avoided, and appropriate measures such as interrupting the inter-vehicle distance control or notifying the driver can be taken.

  In the first and second embodiments, the azimuth angle for assigning priority is divided into 2 or 4 priority angle areas. However, it may be divided into priority angle areas other than 2 and 4 in the same way. Good.

  In the radar apparatus according to the first and second embodiments, when changing the frequency band to be used, the frequency bands to be used after the change are not overlapped, but when the usable frequency band is narrow, etc. Alternatively, the frequency bands may be set to overlap. However, in this case, since there is a possibility of interference even if the frequency band is changed, there is a possibility that the probability that interference avoidance cannot be increased.

  In the radar apparatus according to the first and second embodiments, interference is avoided by changing the frequency band to be used. However, other means such as changing the timing of transmitting electromagnetic waves may be used. Good. For example, a plurality of time directions (horizontal axis directions) in each measurement period are used so that the transmission timing of the radar device itself indicated by the solid line shown in FIG. 12 does not overlap with the transmission timing of another radar device indicated by the broken line. The time band is divided, and the use time band is similarly changed according to the priority order. In this case, the frequency instruction unit 17 in FIG. 1 is replaced with, for example, a transmission time band instruction unit (not shown), and the transmission timing of the transmission signal is controlled by the VCO 3.

  Further, although the radar system of the first and second embodiments uses the FMCW system as a radar system, it is needless to say that interference can be similarly avoided even with other radar systems.

  DESCRIPTION OF SYMBOLS 1 Radar apparatus, 2 Control calculating part, 3 VCO, 4 Distributor, 5 Transmitting antenna, 6 Target object, 7 Other radar apparatus, 8 Receiving antenna, 9 Mixer, 10 Amplifier, 11 Low pass filter, 12 A / D converter , 13 Frequency analysis unit, 14 Target object calculation unit, 15 Interference processing unit, 16 Inter-vehicle distance control processing unit, 17 Frequency indicating unit, 18 In-vehicle LAN, 19 User interface device, 20 Engine control ECU, 21 Brake control ECU, 22 Car Navigation device, M memory.

Claims (4)

A radar device that transmits a frequency-modulated modulated wave and receives a reflected wave reflected by a target object,
Whether the radar device front azimuth is calculated and interference avoidance for the radar device front azimuth stored in advance in the storage unit is executed when the occurrence of interference with the transmission wave from another radar device is determined from the received wave An interference processing unit that performs interference avoidance according to a priority condition that defines the priority order of whether or not ,
The priority condition is obtained by dividing all azimuth angles into a plurality of areas and setting a priority order for each of the divided areas.
The priority condition area is divided into two areas in which the omnidirectional area defines the priority order in the omnidirectional area, and the divided areas are sequentially divided into the divided areas. It is divided into two areas that define the priority order, and the interference processing unit performs interference avoidance according to the upper area, and if not avoided, according to the priority order of the lower divided areas in the area sequentially To further avoid interference,
Radar apparatus characterized by the above. The radar apparatus according to claim 1 , wherein the interference processing unit performs interference avoidance by changing a modulation frequency band of a transmission frequency. The radar apparatus according to claim 1 , wherein the interference processing unit performs interference avoidance by changing a temporal timing at which a transmission wave is transmitted. A method of controlling a radar apparatus that transmits a modulated wave that is frequency-modulated and receives a reflected wave reflected by a target object,
When it is determined from the received wave that there is interference with a transmission wave from another radar device, the radar device front azimuth is calculated, and whether or not to avoid interference with the radar device front azimuth stored in advance is determined. Perform interference avoidance according to the priority conditions that define the priority,
The priority condition is obtained by dividing all azimuth angles into a plurality of areas and setting a priority order for each of the divided areas.
The priority condition area is divided into two areas in which the omnidirectional area defines the priority order in the omnidirectional area, and the divided areas are sequentially divided into the divided areas. It is divided into two areas that define priority, and interference avoidance is performed according to the upper area, and if it is not avoided, further interference avoidance is performed according to the priority of the lower divided areas within the area. Go,
A control method of a radar apparatus characterized by the above.

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