JP2019039750A - Rader system and method for detecting target - Google Patents

Abstract

To provide a rader system and a method for detecting a target that can detect a target more quickly.SOLUTION: The rader system according to an embodiment includes a detection unit and a determination unit. The detection unit detects the difference of angles between the target and the travelling direction in the scanning range, which is a predetermined angular range including the direction of travelling of an own vehicle. The larger the angular difference is when the determination unit detected the first target, the more determination unit determines that a target is not a road surface.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a radar apparatus and a target detection method.

  Conventionally, for example, a vehicle control system for controlling a PCS (Pre-crash Safety System) or AEB (Advanced Emergency Braking System) based on a target such as a vehicle detected by an electronic scanning radar device such as a millimeter wave radar is known. ing.

  The radar apparatus detects the presence of a target by scanning a predetermined angle range including the traveling direction of the host vehicle at a constant period. Then, when the target is detected for the first time, the radar device continues to monitor the target in the next and subsequent cycles, and the finally detected target is an object such as a vehicle or a road surface. Determine whether. For example, the radar device determines whether the vehicle is a road surface based on the angle difference between the predicted angle of the target detected after the next time and the actually detected angle.

Japanese Patent Laying-Open No. 2015-68724

  However, in the conventional technology, for example, in order to determine that the target is a vehicle, the target must be continuously monitored over a plurality of cycles, for example, a cut in which another vehicle suddenly enters the range of scanning from a short distance. When detected by IN, there is a possibility that it cannot be quickly determined that the target is a vehicle.

  The present invention has been made in view of the above, and an object of the present invention is to provide a radar apparatus and a target detection method that can accelerate the discrimination of a target.

  In order to solve the above-described problems and achieve the object, a radar apparatus according to the present invention includes a detection unit and a determination unit. The detection unit detects an angle difference between the target and the traveling direction in a scanning range that is a predetermined angular range including the traveling direction of the host vehicle. The determination unit determines that the target is an object other than the road surface rather than the road surface as the angle difference when the target is detected for the first time by the detection unit is larger.

  According to the present invention, the discrimination of the target can be accelerated.

FIG. 1 is a diagram illustrating an outline of a target detection method according to an embodiment. FIG. 2 is a block diagram illustrating a configuration of the radar apparatus according to the embodiment. FIG. 3 is an explanatory diagram of processing from the previous stage processing of the signal processing unit to the peak extraction processing in the signal processing unit. FIG. 4A is an explanatory diagram of angle estimation processing. FIG. 4B is a process explanatory diagram (part 1) of the pairing process. FIG. 4C is a process explanatory diagram (part 2) of the pairing process. FIG. 5 is a diagram illustrating a probability distribution of a road surface probability or an object probability in an angle difference. FIG. 6 is a diagram illustrating processing contents of the calculation unit. FIG. 7 is a diagram illustrating processing contents of the determination unit. FIG. 8 is a flowchart illustrating a processing procedure of processing executed by the radar apparatus according to the embodiment. FIG. 9 is a diagram illustrating the processing contents of the calculation unit according to the modification.

  Hereinafter, embodiments of a radar apparatus and a target detection method disclosed in the present application will be described in detail with reference to the accompanying drawings. In addition, this invention is not limited by this embodiment. In the following, a case where the radar apparatus 1 is an FM-CW (Frequency Modulated Continuous Wave) system will be described as an example. However, the radar apparatus 1 is based on another system such as an FCM (Fast-Chirp Modulation) system, for example. There may be.

  First, the outline of the target detection method according to the embodiment will be described with reference to FIG. FIG. 1 is a diagram illustrating an outline of a target detection method according to an embodiment. FIG. 1 shows a scene in which another vehicle, which is the target T, is performing a so-called cut-in in which the course is changed and interrupted in front of the host vehicle MC. In FIG. 1, the radar apparatus 1 according to the embodiment first targets in a scanning range R that is a predetermined angle range α including a reference line 100 (hereinafter, traveling direction 100) indicating the traveling direction of the host vehicle MC. An instantaneous value 50 when T is detected is shown.

  The instantaneous value 50 is an instantaneous value detected by a transmission wave transmitted at a predetermined period and a reflected wave of a transmission wave by the target T. For example, the target T and the traveling direction 100 of the host vehicle MC Information such as the angle difference θ, the distance from the host vehicle MC to the target T, and the relative speed of the target T.

  As shown in FIG. 1, the radar apparatus 1 according to the embodiment is mounted in front of, for example, the front grill of the host vehicle MC, and executes the target detection method according to the embodiment. The radar device 1 may be mounted at other locations such as a windshield, a rear grille, left and right side portions (for example, left and right door mirrors), a rear portion of the host vehicle MC, and the like. When provided at the rear part of the host vehicle MC, the traveling direction 100 is a direction toward the rear of the host vehicle MC.

  In the target detection method according to the embodiment, it is determined whether the type of the target T is an object such as a vehicle or a road surface based on the angle difference θ when the target T is detected for the first time. Such an object is not limited to a vehicle, and may be another moving body, or may be a stationary object that hinders traveling of the host vehicle MC.

  Here, a conventional target detection method will be described. In the conventional target detection method, for example, in order to determine that the target is a vehicle, it is necessary to continuously monitor the target over a plurality of cycles. That is, it is determined whether the vehicle or the road surface based on instantaneous values detected after the next time.

  However, for example, when another vehicle enters the scanning range from a relatively short distance due to cut-in, the conventional method may not be able to quickly determine that the target is a vehicle.

  Therefore, in the target detection method according to the embodiment, it is determined based on the instantaneous value 50 detected for the first time whether the target T is an object such as a vehicle or a road surface. Specifically, in the target detection method according to the embodiment, first, the angle difference θ of the instantaneous value 50 corresponding to the target T is detected.

  Subsequently, in the target detection method according to the embodiment, the larger the angle difference θ when the target T is detected for the first time, the more the target T is an object other than the road surface, that is, the target T is a vehicle. Is determined.

  In other words, in the target detection method according to the embodiment, the determination process is performed using the characteristic that enters the inside from the outside of the scanning range R, which is a feature of cut-in. That is, the closer the angle difference θ is to the angle range α of the scanning range R, the higher the possibility of being a vehicle.

  On the other hand, the closer the instantaneous value 50 detected for the first time is to the traveling direction 100, the higher the possibility that the road surface is. In other words, the target T that is suddenly detected in the vicinity of the center of the scanning range R is considered to be unlikely to be a vehicle.

  As the target T that suddenly appears in the center of the scanning range R in this way, a so-called road surface ghost is conceivable. Thus, since it is possible to determine whether the vehicle is a road surface from the angle difference θ detected at the first time, the determination of the target T can be accelerated.

  In the target detection method according to the embodiment, the initial value of the accuracy indicating the likelihood that the target T is a vehicle is calculated based on the initial angle difference θ. For details of this point, refer to FIG. Will be described later.

  Next, the configuration of the radar apparatus 1 according to the embodiment will be described in detail with reference to FIG. FIG. 2 is a block diagram illustrating a configuration of the radar apparatus 1 according to the embodiment. In FIG. 2, only components necessary for explaining the features of the present embodiment are represented by functional blocks, and descriptions of general components are omitted.

  In other words, each component illustrated in FIG. 2 is functionally conceptual and does not necessarily need to be physically configured as illustrated. For example, the specific form of distribution / integration of each functional block is not limited to the one shown in the figure, and all or a part thereof is functionally or physically distributed in arbitrary units according to various loads or usage conditions.・ It can be integrated and configured.

  As shown in FIG. 2, the radar apparatus 1 includes a transmission unit 10, a reception unit 20, and a processing unit 30. The radar device 1 is connected to a vehicle control device 2 that controls the behavior of the host vehicle MC.

  The vehicle control device 2 performs vehicle control such as PCS (Pre-crash Safety System) and AEB (Advanced Emergency Braking System) based on the detection result of the target T by the radar device 1.

  The transmission unit 10 includes a signal generation unit 11, an oscillator 12, and a transmission antenna 13. The signal generation unit 11 generates a modulation signal for transmitting a millimeter wave frequency-modulated with a triangular wave under the control of a transmission / reception control unit 31 described later. The oscillator 12 generates a transmission signal based on the modulation signal generated by the signal generation unit 11 and outputs the transmission signal to the transmission antenna 13. As shown in FIG. 2, the transmission signal generated by the oscillator 12 is also distributed to the mixer 22 described later.

  The transmission antenna 13 converts the transmission signal from the oscillator 12 into a transmission wave and outputs the transmission wave to the outside of the host vehicle MC. The transmission wave output from the transmission antenna 13 is a continuous wave that is frequency-modulated with a triangular wave. A transmission wave transmitted from the transmission antenna 13 to the outside of the host vehicle MC, for example, forward is reflected by a target T such as a preceding vehicle and becomes a reflected wave.

  The receiving unit 20 includes a plurality of receiving antennas 21 that form an array antenna, a plurality of mixers 22, and a plurality of A / D conversion units 23. The mixer 22 and the A / D conversion unit 23 are provided for each reception antenna 21.

  Each receiving antenna 21 receives a reflected wave from the target T as a received wave, converts the received wave into a received signal, and outputs the received signal to the mixer 22. The number of receiving antennas 21 shown in FIG. 2 is four, but it may be three or less or five or more.

  The reception signal output from the reception antenna 21 is amplified by an amplifier (not shown) (for example, a low noise amplifier) and then input to the mixer 22. The mixer 22 mixes a part of the distributed transmission signal and the reception signal input from the reception antenna 21 to remove unnecessary signal components, generates a beat signal, and outputs the beat signal to the A / D conversion unit 23. .

  The beat signal is a differential wave between the transmission wave and the reflected wave, and is a frequency of the transmission signal (hereinafter referred to as “transmission frequency”) and a frequency of the reception signal (hereinafter referred to as “reception frequency”). It has a beat frequency that makes a difference. The beat signal generated by the mixer 22 is converted to a digital signal by the A / D conversion unit 23 and then output to the processing unit 30.

  The processing unit 30 includes a transmission / reception control unit 31, a signal processing unit 32, and a storage unit 33. The signal processing unit 32 includes a detection unit 32a, a calculation unit 32b, a determination unit 32c, and a target data generation unit 32d.

  The storage unit 33 stores history data 33a. The history data 33a is information including a history of target data in a series of signal processing executed by the signal processing unit 32.

  The processing unit 30 is a microcomputer including, for example, a CPU (Central Processing Unit), a ROM (Read Only Memory) corresponding to the storage unit 33, a RAM (Random Access Memory), a register, and other input / output ports. The entire apparatus 1 is controlled.

  The microcomputer CPU functions as the transmission / reception control unit 31 and the signal processing unit 32 by reading and executing the program stored in the ROM. Note that the transmission / reception control unit 31 and the signal processing unit 32 may all be configured by hardware such as an application specific integrated circuit (ASIC) or a field programmable gate array (FPGA).

  The transmission / reception control unit 31 controls the transmission unit 10 including the signal generation unit 11 and the reception unit 20. The signal processing unit 32 periodically executes a series of signal processing. Next, each component of the signal processing unit 32 will be described.

  The detection unit 32a includes a frequency analysis unit 321a, a peak extraction unit 322a, and an instantaneous value generation unit 323a. In the scanning range R that is a predetermined angle range α including the traveling direction 100 of the host vehicle MC, the target T And the angle difference θ between the traveling directions 100 is detected. Specifically, the detection unit 32a detects an instantaneous value 50 corresponding to the target T based on the frequency-modulated transmission wave and the reflected wave of the transmission wave by the target T.

  The frequency analysis unit 321a performs fast Fourier transform (FFT) processing (hereinafter referred to as “FFT processing”) on the beat signal input from each A / D conversion unit 23, and peaks the result. The data is output to the extraction unit 322a. The result of the FFT processing is a frequency spectrum of the beat signal, and a power value (signal level) for each frequency of the beat signal (for each frequency bin set at a frequency interval corresponding to the frequency resolution).

  The peak extraction unit 322a extracts a peak frequency that becomes a peak in the result of the FFT processing by the frequency analysis unit 321a, and outputs the extraction result to the instantaneous value generation unit 323a. The peak extraction unit 322a extracts a peak frequency for each of an “UP section” and a “DN section” of a beat signal to be described later.

  The instantaneous value generation unit 323a executes angle estimation processing for calculating the arrival angle of the reflected wave corresponding to each of the peak frequencies extracted by the peak extraction unit 322a and its power value. Note that at the time of execution of the angle estimation process, the arrival angle is an angle at which the target T is estimated to exist (that is, the angle difference θ), and therefore may be referred to as “estimated angle” below.

  In addition, the instantaneous value generation unit 323a executes a pairing process for determining a correct combination of peak frequencies of the “UP section” and the “DN section” based on the calculation result of the calculated estimated angle and power value.

  The instantaneous value generation unit 323a calculates the distance and relative speed of each target T with respect to the host vehicle MC from the determined combination result. The instantaneous value generation unit 323a outputs the calculated estimated angle (angle difference θ), distance, and relative speed of each target T to the calculation unit 32b as the instantaneous value 50 for the latest period (latest scan).

  In order to make the explanation easy to understand, the flow of processing from the previous stage processing of the signal processing unit 32 to the processing in the signal processing unit 32 is shown in FIGS. FIG. 3 is an explanatory diagram of processing from the previous stage processing of the signal processing unit 32 to the peak extraction processing in the signal processing unit 32.

  FIG. 4A is an explanatory diagram of angle estimation processing. 4B and 4C are process explanatory diagrams (part 1) and (part 2) of the pairing process. Note that FIG. 3 is divided into three regions by two thick downward white arrows. In the following, each of these areas will be described as an upper stage, a middle stage, and a lower stage in order.

  As shown in the upper part of FIG. 3, the transmission signal fs (t) is transmitted from the transmission antenna 13 as a transmission wave, then is reflected by the target T and arrives as a reflection wave, and the reception signal fr ( t).

  At this time, as shown in the upper part of FIG. 3, the reception signal fr (t) is delayed by a time difference T with respect to the transmission signal fs (t) according to the distance between the host vehicle MC and the target T. . Due to the time difference T and the Doppler effect based on the relative speed of the host vehicle MC and the target, the beat signal has a frequency fup in the “UP section” in which the frequency increases and a frequency fdn in the “DN section” in which the frequency decreases. Is obtained as a repeated signal (see the middle of FIG. 3).

  The lower part of FIG. 3 schematically shows the result of FFT processing of the beat signal by the frequency analysis unit 321a for each of the “UP section” side and the “DN section” side.

  As shown in the lower part of FIG. 3, after the FFT processing, waveforms in the respective frequency regions on the “UP section” side and the “DN section” side are obtained. The peak extraction unit 322a extracts a peak frequency that becomes a peak in the waveform.

  For example, in the case of the example shown in the lower part of FIG. 3, the peak extraction threshold is used, and on the “UP section” side, the peaks Pu1 to Pu3 are determined as peaks, and the peak frequencies fu1 to fu3 are extracted.

  On the “DN section” side, the peaks Pd1 to Pd3 are also determined as peaks by the peak extraction threshold, and the peak frequencies fd1 to fd3 are extracted, respectively.

  Here, the frequency component of each peak frequency extracted by the peak extraction unit 322a may be a mixture of reflected waves from a plurality of targets. Therefore, the instantaneous value generation unit 323a performs angle estimation processing for calculating the direction for each peak frequency, and analyzes the presence of the target T corresponding to each peak frequency.

  The azimuth calculation in the instantaneous value generation unit 323a can be performed using a known arrival direction estimation method such as ESPRIT (Estimation of Signal Parameters via Rotational Invariance Techniques).

  FIG. 4A schematically shows the azimuth calculation result of the instantaneous value generation unit 323a. The instantaneous value generation unit 323a calculates an estimated angle of each target T (each reflection point) corresponding to each of the peaks Pu1 to Pu3 from each peak Pu1 to Pu3 of the azimuth calculation result. Moreover, the magnitude | size of each peak Pu1-Pu3 becomes a power value. As illustrated in FIG. 4B, the instantaneous value generation unit 323a performs the angle estimation process on each of the “UP section” side and the “DN section” side.

  Then, the instantaneous value generation unit 323a performs a pairing process for combining each peak having an estimated angle and a power value close to each other in the azimuth calculation result. Further, from the combination result, the instantaneous value generation unit 323a calculates the distance and relative velocity of each target T (each reflection point) corresponding to each peak combination.

  The distance can be calculated based on the relationship of “distance ∝ (fup + fdn)”. The relative speed can be calculated based on the relationship of “speed-up (fup−fdn)”. As a result, as shown in FIG. 4C, a pairing process result indicating the instantaneous value 50 of the estimated angle, distance, and relative speed of each reflection point RP with respect to the host vehicle MC is obtained.

  Returning to FIG. 2, the calculation unit 32b will be described. The calculation unit 32b calculates the accuracy indicating the probability that the target T is an object other than the road surface based on the angle difference θ included in the instantaneous value 50 detected by the detection unit 32a. Specifically, the calculation unit 32b calculates an initial value of accuracy based on the angle difference θ detected for the first time, and calculates an added value of accuracy based on the angle difference θ detected after the next time.

  Specifically, the calculating unit 32b acquires a road surface probability that is the road surface of the target T or an object probability distribution that is an object at an angle difference θ, and calculates the accuracy (initial value) based on the probability distribution. . Here, the calculation method of the initial value of accuracy by the calculation unit 32b will be described in detail with reference to FIGS.

  FIG. 5 is a diagram showing a probability distribution of road surface probability or object probability at an angle difference θ. In the graph of FIG. 5, the horizontal axis indicates the angle difference θ, and the vertical axis indicates the road surface probability or the object probability. In the graph of FIG. 5, the object probability is indicated by a solid line, and the road surface probability is indicated by a broken line.

  In addition, when the angle difference θ is zero, the traveling direction 100 is indicated, and −α / 2 and α / 2 respectively indicate left and right boundary lines in the scanning range R (see FIG. 1). Such a probability distribution is generated based on an actual measurement value of the angle difference θ in the initial detection obtained in advance through experiments or the like.

  As shown in FIG. 5, the road surface probability and the object probability have a normal distribution shape centered on zero angle difference θ. Further, the convex shape of the object probability is gentler than the road surface probability. Specifically, for example, the object probability is higher than the road surface probability from an angle difference θ of −α / 2 (or α / 2) to a certain angle difference θ.

  And the probability of both is reversed at a certain angle difference θ. That is, the road surface probability is higher than the object probability. When the angle difference θ is around zero, the difference between the road surface probability and the object probability is maximized.

  In other words, in this probability distribution, when the angle difference θ is from zero to a certain angle difference θ, there is a high possibility that the target T is a road surface, and from a certain angle difference θ to −α / 2 (or α / 2). Indicates that there is a high possibility that the target T is an object.

  For example, when attention is paid to the object probability, the probability is higher as the angle difference θ is closer to zero. This is because the possibility that an object appears from the boundary line in front of the scanning range R is included. In other words, the probability that the object that is the target T approaches from the front is higher than the probability of cut-in. Thus, by using the probability distribution, the road surface probability and the object probability can be easily calculated.

  Next, with reference to FIG. 6, a method of calculating the accuracy using the probability distribution will be described. FIG. 6 is a diagram illustrating the processing contents of the calculation unit 32b. FIG. 6 shows a scene in which two instantaneous values 50a and 50b are newly obtained within the scanning range R. In FIG. 6, it is assumed that the angle difference θ1 of the instantaneous value 50a is larger than the angle difference θ2 of the instantaneous value 50b. Further, the angle difference θ1 is on the −α / 2 (α / 2) side from the intersection between the road surface probability and the object probability in the probability distribution (see FIG. 5), and the angle difference θ2 is on the zero side from the intersection. And

  That is, in light of the above probability distribution (see FIG. 5), the target T corresponding to the instantaneous value 50a has a higher possibility of being an object than the possibility of being a road surface. On the other hand, the target T corresponding to the instantaneous value 50b has a higher possibility of being a road surface than a possibility of being an object.

  Then, the calculation unit 32b calculates the accuracy indicating the probability of being an object for each of the instantaneous values 50a and 50b based on the road surface probability and the object probability obtained from the probability distribution. For example, the calculation unit 32b can calculate the accuracy by subtracting the road surface probability from the object probability. Thereby, the accuracy in the instantaneous value 50a becomes a positive value, and the accuracy in the instantaneous value 50b becomes a negative value.

  Alternatively, the calculation unit 32b may calculate the ratio of the object probability to the road surface probability. In this case, the instantaneous value 50a is a value greater than 1, and the instantaneous value 50b is a value smaller than 1.

  The calculation of the accuracy is not limited to the above-described method, and any calculation method may be used as long as the accuracy of the instantaneous value 50a is larger than the accuracy of the instantaneous value 50b.

  In this manner, the calculation unit 32b can easily perform the determination process on the road surface or the vehicle by the determination unit 32c described later by calculating the accuracy.

  In the above description, the method of calculating the initial value of the accuracy based on the angle difference θ detected for the first time has been described. However, the calculation unit 32b is based on the angle difference θ detected from the next time on the same target T. To calculate the accuracy value.

  Specifically, first, the calculation unit 32b predicts the angle difference θt + 1 detected next time at time t + 1 from the angle difference θt detected at time t at the first time. For example, the calculation unit 32b predicts the next angle difference θt + 1 in consideration of the relative speed and distance of the first instantaneous value 50.

  Subsequently, the calculation unit 32b compares the predicted angle difference θt + 1 with the angle difference θt + 1 actually detected at time t + 1, and calculates an accuracy addition value based on the comparison result. For example, the calculation unit 32b increases the added value as the difference between the predicted angle difference θt + 1 and the angle difference θt + 1 actually detected at time t + 1 is smaller. The calculation unit 32b outputs the initial value and the added value of the calculated accuracy to the determination unit 32c.

  Returning to FIG. 2, the determination unit 32c will be described. The determination unit 32c performs a determination process as to whether the target T is a road surface or an object based on the accuracy calculated by the calculation unit 32b. Here, the processing content of the determination part 32c is demonstrated using FIG.

  FIG. 7 is a diagram illustrating processing contents of the determination unit 32c. In the graph of FIG. 7, the horizontal axis represents time, and the vertical axis represents the cumulative value of accuracy. The cumulative value is a value obtained by integrating the initial value of accuracy with the added value from the next time. FIG. 7 shows a graph when two instantaneous values 50a and 50b (see FIG. 6) continue to be detected after the next time.

  As illustrated in FIG. 7, the determination unit 32 c determines that the target T is an object when the accuracy accumulation value is equal to or greater than a predetermined threshold. In other words, the determination unit 32c continues to determine that the target T is a road surface while the accuracy accumulation value is less than the predetermined threshold value.

  In this way, by identifying an object based on an initial value of accuracy and an accumulated value including an added value, for example, a target T that can be detected only once (or very few times) due to the influence of noise or the like. An erroneous determination that the object is an object can be prevented.

  Further, as illustrated in FIG. 7, the determination unit 32c sets the initial value of the accuracy of the instantaneous value 50a higher than the reference value based on the calculation result of the calculation unit 32b. As a result, the time when the instantaneous value 50a is determined to be an object can be advanced, and the time when the instantaneous value 50b is determined to be an object is delayed, that is, the instantaneous value 50b is erroneously determined to be an object. Can be prevented. Note that the cumulative value of accuracy is reset every predetermined time.

  Returning to FIG. 2, the target data generation unit 32d will be described. The target data generation unit 32d generates target data based on the determination result of the determination unit 32c. The target data includes the angle difference θ of the instantaneous value 50, the relative speed, the distance, and the type of the target T (object or road surface).

  Next, a processing procedure of processing executed by the radar apparatus 1 according to the embodiment will be described with reference to FIG. FIG. 8 is a flowchart illustrating a processing procedure of processing executed by the radar apparatus 1 according to the embodiment.

  As shown in FIG. 8, first, the detection unit 32a detects an instantaneous value 50 including the angle difference θ between the target T and the traveling direction 100 (step S101). Subsequently, the calculation unit 32b determines whether or not the new instantaneous value 50, that is, the instantaneous value 50 when the target T is detected for the first time (step S102).

  When the calculation unit 32b has a new instantaneous value 50 (step S102, Yes), the calculation unit 32b calculates an initial value of the accuracy indicating the probability that the target T is an object (step S103). Subsequently, the determination unit 32c updates the cumulative value of accuracy based on the calculation result of the calculation unit 32b (step S104).

  Subsequently, the determination unit 32c determines whether or not the accumulated accuracy value is equal to or greater than a predetermined threshold (step S105). If the cumulative value is equal to or greater than the threshold (Yes at Step S105), the determination unit 32c determines that the target T corresponding to the instantaneous value 50 is an object, that is, a vehicle (Step S106), and ends the process.

  On the other hand, when the calculation unit 32b is not the new instantaneous value 50, that is, the instantaneous value 50 of the target T that has been detected twice or more in Step S102 (No in Step S102), the calculation unit 32b calculates the accuracy addition value. Calculation is performed (step S107), and the process proceeds to step S104.

  In step S105, when the cumulative value of accuracy is less than the threshold value (No in step S105), the calculation unit 32b determines that the target T corresponding to the instantaneous value 50 is a road surface (step S108), and performs processing. finish.

  As described above, the radar apparatus 1 according to the embodiment includes the detection unit 32a and the determination unit 32c. The detection unit 32a detects an angle difference θ between the target T and the traveling direction 100 in a scanning range R that is a predetermined angular range α including the traveling direction 100 of the host vehicle MC. The determination unit 32c determines that the target T is an object other than the road surface rather than the road surface as the angle difference θ when the target T is first detected by the detection unit 32a is larger. Thereby, the discrimination of the target can be accelerated.

  In the above-described embodiment, the radar apparatus 1 is provided in the host vehicle MC, but it is needless to say that the radar apparatus 1 may be provided in a moving body other than the vehicle, such as a ship or an aircraft.

  In each of the above-described embodiments, ESPRIT is given as an example of the direction-of-arrival estimation method used by the radar apparatus 1, but is not limited thereto. For example, DBF (Digital Beam Forming), PRISM (Propagator method based on an Improved Spatial-smoothing Matrix), MUSIC (Multiple Signal Classification), or the like may be used.

  In the embodiment described above, the initial value and the added value of the accuracy are calculated by the calculation unit 32b. However, the present invention is not limited to this. For example, the angle difference θ detected first by the detection unit 32a is directly used. The determination unit 32c may determine whether the object is a road surface or an object.

  The calculation unit 32b calculates the initial value of the accuracy based only on the angle difference θ. However, for example, the initial value may be calculated in consideration of the distance of the instantaneous value 50. This point will be described with reference to FIG.

  FIG. 9 is a diagram illustrating processing contents of the calculation unit 32b according to the modification. In FIG. 9, two instantaneous values 50c and 50d having the same angle difference θ are detected, and it is assumed that the instantaneous value 50d is farther from the vehicle MC than the instantaneous value 50c. Further, the angle difference θ shown in FIG. 9 is an angle difference having a road surface probability higher than the object probability in the probability distribution (see FIG. 5).

  The calculation unit 32b calculates the accuracy based on the angle difference θ and the distance to the host vehicle MC. Specifically, the calculation unit 32b increases as the distance becomes longer when the angle difference θ is equal to or less than a predetermined value. Increase the initial value of accuracy. It is assumed that the predetermined value here is within an angle difference range in which the road surface probability is higher than the object probability in the probability distribution.

  That is, as shown in the lower part of FIG. 9, the calculation unit 32b sets the initial value of the accuracy of the instantaneous value 50c and the instantaneous value 50d to a value smaller than the reference value, and sets the instantaneous value 50d higher than the instantaneous value 50c. Set to value.

  That is, even if the angle difference θ is a small value, the longer the distance, the higher the possibility that the target T is an object that approaches from the front. Thereby, it can prevent that the target T which approaches from the front continues being determined as a road surface, and can determine with it being a vehicle at an early stage.

  Further effects and modifications can be easily derived by those skilled in the art. Thus, the broader aspects of the present invention are not limited to the specific details and representative embodiments shown and described above. Accordingly, various modifications can be made without departing from the spirit or scope of the general inventive concept as defined by the appended claims and their equivalents.

DESCRIPTION OF SYMBOLS 1 Radar apparatus 32 Signal processing part 32a Detection part 32b Calculation part 32c Judgment part 32d Target data generation part 33 Storage part 33a History data 50 Instantaneous value MC Own vehicle T Target R Scan range θ Angle difference α Angle range

Claims (7)

A detection unit that detects an angular difference between the target and the traveling direction in a scanning range that is a predetermined angular range including the traveling direction of the host vehicle;
A radar unit comprising: a determination unit that determines that the target is an object other than the road surface rather than a road surface as the angle difference when the target is first detected by the detection unit is larger. . A probability distribution based on the measured value of the angle difference and the road surface probability that is the road surface or the object probability that is the object is obtained, and the accuracy that indicates the probability that the target is the object is obtained based on the probability distribution. A calculation unit for calculating,
The determination unit
The radar apparatus according to claim 1, wherein a determination process is performed to determine whether the target is the road surface or the object based on the accuracy calculated by the calculation unit. The calculation unit includes:
An initial value of the accuracy is calculated based on the angular difference when the target is detected for the first time by the detection unit, and based on the angular difference when the target is detected next time by the detection unit. To calculate the added value of the accuracy,
The determination unit
The radar apparatus according to claim 2, wherein when the cumulative value of the accuracy obtained by adding the added value to the initial value is equal to or greater than a predetermined threshold, the target is determined to be the object. . The calculation unit includes:
When the object probability is higher than the road surface probability, the initial value of the accuracy is made higher than a reference value, and when the object probability is lower than the road surface probability, the initial value of the accuracy is made lower than the reference value. The radar apparatus according to claim 3. The detector is
Further detecting the distance from the host vehicle to the target;
The calculation unit includes:
The radar apparatus according to any one of claims 2 to 4, wherein the accuracy is calculated based on the angle difference and the distance. The calculation unit includes:
The radar apparatus according to claim 5, wherein, when the angular difference is equal to or smaller than a predetermined value, the accuracy is increased as the distance is longer. A detection step of detecting an angle difference between the target and the traveling direction in a scanning range that is a predetermined angular range including the traveling direction of the host vehicle;
A determination step of determining that the target is an object other than the road surface rather than the road surface as the angle difference when the target is detected for the first time by the detection step is larger. Detection method.

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