JP2006038687A - Moving object detection device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To detect only a moving object efficiently by suppressing a reflected signal component reflected from a stationary object when a host vehicle is traveling.
When a radar apparatus 1 detects a moving object around a host vehicle, a signal processing unit 4 calculates a frequency spectrum of a frequency difference signal by an FFT processing unit 32 and a frequency offset amount calculating unit 33 A Doppler shift amount corresponding to the host vehicle speed is calculated. The frequency offset unit 34 offsets the frequency spectrum in the transmission frequency rising period in the positive direction by the amount of Doppler shift, and offsets the frequency spectrum in the transmission frequency falling period in the negative direction by the amount of Doppler shift. Detects a moving object based on a frequency spectrum obtained by calculating a difference between a frequency spectrum offset in the positive direction and a frequency spectrum offset in the negative direction.
[Selection] Figure 1

Description

  The present invention relates to a moving object detection device that is mounted on, for example, a vehicle and detects an obstacle or the like existing around the vehicle.

  Conventionally, laser radar using infrared rays, radio wave radar using millimeter waves, and the like are known as sensors used in obstacle detection systems and ACC (Adaptive Cruise Control) systems. Although these obstacle detection systems and ACC systems are premised on the use mainly on automobile roads, their application to urban driving is being studied. Thus, in a state where the vehicle is traveling in an urban area, there are many stationary objects and moving objects as obstacles around the vehicle. Therefore, it is necessary to detect the moving objects more efficiently.

On the other hand, as a radio wave radar device that detects a moving object without being affected by a reflected signal from a stationary object in a state where the host vehicle is stationary, An FM (Frequency Modulation) -CW (Continuous Wave) radar that modulates the frequency of the transmitted radio wave, and by calculating the difference between the power spectrum obtained from the frequency rise period and the power spectrum obtained from the frequency drop part, thereby moving the object There was something to extract only.
Japanese Patent Laid-Open No. 6-214017

  However, in a scene where the host vehicle is traveling in an urban area, the stationary object also moves at a relative speed corresponding to the vehicle speed of the host vehicle, so that a reflection signal corresponding to the relative speed is input, and the power spectrum However, the process of not detecting a stationary object could not be performed only by the difference process.

  Therefore, the present invention has been proposed in view of the above-described situation, and when the host vehicle is traveling, the reflected signal component reflected from the stationary object is suppressed and the moving object is efficiently detected. It is an object of the present invention to provide a moving object detection device that can perform the above-described operation.

  The moving object detection device according to the present invention performs transmission according to a change in intensity of a triangular wave signal, transmits a transmission signal including a transmission frequency increase period and a transmission frequency decrease period, and a transmission transmitted from the transmission means. A signal is reflected by an object, the reflected transmission signal is received as a reception signal, a reception means for generating a frequency difference signal indicating a frequency difference between the reception signal and the transmission signal, and a frequency difference signal generated by the reception means And signal processing means for detecting a moving object around the host vehicle.

  When detecting a moving object around the own vehicle by using such a moving object detection device, the signal processing means calculates the frequency spectrum of the frequency difference signal by the frequency analysis means and at the same time by the frequency offset amount calculation means. Is input, and a frequency shift amount corresponding to the vehicle speed is calculated. Then, the frequency offset means offsets the frequency spectrum in the transmission frequency rising period in the positive direction by the frequency shift amount, and offsets the frequency spectrum in the transmission frequency falling period in the negative direction by the frequency shift amount. By detecting the moving object based on the frequency spectrum obtained by calculating the difference between the frequency spectrum offset in the positive direction by the frequency offset means and the frequency spectrum offset in the negative direction by the frequency offset means, Solve the problem.

  According to the moving object detection device of the present invention, the frequency spectrum indicating the frequency difference between the transmission signal and the reception signal is calculated, and the frequency spectrum of the transmission frequency rising period is shifted in the positive direction by the frequency shift amount based on the own vehicle speed. In addition, by shifting the frequency spectrum of the transmission frequency falling period in the negative direction by the frequency shift amount based on the own vehicle speed, the frequency shift generated by reflection from a stationary object having a relative speed corresponding to the own vehicle speed is transmitted. It can be replaced with the same frequency component in the rising period and the transmission frequency falling period. Therefore, according to this moving object detection device, the frequency component reflected by the stationary object is suppressed by calculating the difference between the frequency spectrum during the transmission frequency rising period and the frequency spectrum during the transmission frequency falling period, and The reflected frequency component can be detected, and the detection efficiency of the moving object can be improved.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  A radar apparatus to which the present invention is applied is a moving object detection apparatus that receives infrared light that is emitted from infrared light and reflected from a target, or a moving object detection apparatus that receives radio waves that are emitted from a target and reflected from the target. Applied. As a method for obtaining the position of a target, this radar apparatus transmits a continuous wave that is subjected to frequency modulation or amplitude modulation in a triangular wave shape, and calculates a distance based on the frequency displacement or phase displacement of a reflected signal. Continuous Wave) method. The radar apparatus 1 is mounted on the host vehicle, for example, and detects a distance and a relative speed to a moving object excluding a stationary object among targets existing around the host vehicle. Hereinafter, a first embodiment and a second embodiment of the present invention will be described.

[First Embodiment]
The present invention is applied to, for example, the radar apparatus 1 according to the first embodiment configured as shown in FIG.

[Configuration of Radar Device 1]
The radar apparatus 1 transmits a radio wave that is a transmission wave toward the front of the host vehicle, and receives a radio wave reflected by a target as a reception wave. As shown in FIG. 1, the radar apparatus 1 includes a signal transmission unit 2 that transmits a radio wave as a transmission wave, a signal reception unit 3 that receives a reflected radio wave as a reception wave, the signal transmission unit 2 and the signal reception unit. 3 and a signal processing unit 4 that recognizes a target ahead of the host vehicle.

  The signal transmission unit 2 includes a VCO (Voltage Controlled Oscillator) 11 connected to the signal processing unit 4, a distributor 12, and a transmission antenna 13 that transmits a transmission wave.

  The signal sending unit 2 receives the triangular wave signal from the signal processing unit 4 and performs the oscillation operation in which the VCO 11 changes the frequency according to the intensity of the triangular wave signal, thereby performing frequency modulation of the transmission wave transmitted from the transmission antenna 13. Then, the transmission signal subjected to the frequency modulation is supplied to the distributor 12. When the transmission signal from the VCO 11 is supplied, the distributor 12 distributes the transmission signal at a predetermined power ratio. The transmission signal distributed by the distributor 12 is supplied to the transmission antenna 13 and the signal receiving unit 3. When the transmission signal is supplied from the distributor 12, the transmission antenna 13 transmits a transmission wave according to the frequency and intensity of the transmission signal.

  The signal receiving unit 3 is an amplification amplifier connected to the receiving antenna 21, the mixer circuit 22, and the signal processing unit 4 that receives a radio wave transmitted from the signal sending unit 2 and reflected by a target ahead of the host vehicle as a received wave. 23.

  When the reception wave is received by the reception antenna 21, the signal reception unit 3 supplies the reception signal to the mixer circuit 22 as a reception signal corresponding to the frequency and amplitude of the reception wave. When the reception signal is supplied from the reception antenna 21, the mixer circuit 22 mixes the reception signal and the transmission signal (LO signal) supplied from the distributor 12 to generate a reception IF signal that is a frequency difference signal. This is supplied to the amplification amplifier 23. The amplification amplifier 23 amplifies the mixed reception IF signal from the mixer circuit 22 to a predetermined voltage value and supplies the amplified signal to the signal processing unit 4. Since the reception IF signal supplied from the signal receiving unit 3 to the signal processing unit 4 is mixed with the transmission signal by the mixer circuit 22, the frequency component shifted by the reflection of the target and the frequency of the transmission signal The difference frequency from the component is included.

  The signal processing unit 4 includes a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), and the like, and a control processing program for the signal sending unit 2 and the signal receiving unit 3 stored in the ROM. The functional units 31 to 35 are realized by executing the target recognition program.

  The signal processing unit 4 includes a triangular wave generation unit 31 that supplies a triangular wave signal to the signal transmission unit 2 and an FFT (Fast Fourier Transform) process that is a frequency analysis unit that receives a reception IF signal from the signal reception unit 3. A frequency offset amount calculation unit 33, a frequency offset unit 34, and a target recognition unit 35 connected to a vehicle speed sensor (not shown).

  When the signal processing unit 4 transmits a transmission wave from the signal transmission unit 2, for example, the target recognition unit 35 gives a command to generate a triangular wave signal to the triangular wave generation unit 31 to operate the triangular wave generation unit 31. Thereby, the triangular wave generation unit 31 supplies a triangular wave signal for frequency modulation by the VCO 11 to the signal transmission unit 2 and causes the signal transmission unit 2 to transmit a transmission wave.

  In addition, the signal processing unit 4 transmits a transmission wave from the signal transmission unit 2, and the reception IF signal from the signal reception unit 3 is received by the FFT processing unit 32. The FFT processing unit 32 creates a frequency spectrum of the frequency difference signal by performing a fast Fourier transform process on the supplied reception IF signal, and supplies the frequency spectrum to the frequency offset unit 34.

  Further, when the signal processing unit 4 recognizes the target by the target recognition unit 35, the frequency offset amount calculation unit 33 reads the vehicle speed information from a vehicle speed sensor (not shown). The frequency offset amount calculation unit 33 calculates a Doppler shift amount that is a frequency shift amount corresponding to the host vehicle speed, and supplies the Doppler shift amount to the frequency offset unit 34. The Doppler shift amount calculated by the frequency offset amount calculation unit 33, which will be described later, calculates a frequency amount that cancels out the frequency shift amount between the transmission wave and the reception wave that are generated due to the relative velocity with the stationary object. To do. The amount of Doppler shift is determined by table data that shifts the frequency by a larger amount when the relative speed of the stationary object is high, that is, as the speed of the host vehicle increases.

  When the frequency spectrum from the FFT processing unit 32 and the Doppler shift amount from the frequency offset amount calculating unit 33 are supplied, the frequency offset unit 34 uses the Doppler shift amount and the frequency spectrum of the reception IF signal in the transmission frequency increase period. Is shifted in the positive direction, and the frequency spectrum of the reception IF signal at the frequency drop portion of the transmission signal is shifted in the negative direction. That is, the frequency offset unit 34 is the frequency spectrum of the reception IF signal during the period in which the frequency of the transmission signal is increased and is information shifted in the positive direction by the amount of Doppler shift (frequency spectrum in the transmission frequency increase period). , Supplies the target recognition unit 35 with the frequency spectrum of the reception IF signal during the period when the frequency of the transmission signal is lowered and the frequency shifted in the negative direction by the Doppler shift amount (spectrum during the transmission frequency fall period). To do.

  The target recognizing unit 35, when the rising frequency spectrum information and the falling frequency spectrum information are supplied from the frequency offset unit 34, calculates the difference between the frequency spectrum of the transmission frequency rising period and the frequency spectrum of the transmission frequency falling period. Then, the moving object excluding the stationary object existing in front of the host vehicle is detected. At this time, the target recognition unit 35 calculates the distance of the moving object and the relative speed with respect to the host vehicle, and supplies the calculation result to the ACC control unit and the like.

[Operation of Radar Device 1]
Next, a radar operation in the radar apparatus 1 configured as described above will be described.

  First, the radar operation of the radar apparatus 1 when the host vehicle is traveling will be described with reference to FIG.

  When a triangular wave signal as shown in FIG. 2 (a) is supplied from the triangular wave generator 31 to the VCO 11, the radar apparatus 1 transmits a transmission signal whose transmission frequency changes as shown in FIG. 2 (b). Oscillate. The transmission signal is a period in which the frequency gradually increases during a period from time t1 when the intensity of the triangular wave signal increases, and a period from time t1 to time t2 in which the intensity of the triangular wave signal decreases is a period in which the frequency gradually decreases. The transmission frequency increase period and the transmission frequency decrease period are repeated. Accordingly, the transmission wave transmitted from the transmission antenna 13 is also an electromagnetic wave in which the transmission frequency increase period and the transmission frequency decrease period are repeated as in the case of the transmission signal.

  The radar apparatus 1 detects a received wave as indicated by a solid line in FIG. The received wave has a time delay compared to the transmission wave indicated by the dotted line in FIG. 2C according to the distance from the radar apparatus 1 to the target. A frequency shift due to the Doppler effect occurs according to the relative speed of the. Here, the received wave includes a frequency shift based on the relative speed generated when the host vehicle travels and a frequency shift based on the relative speed generated when the target moves.

  The reception signal corresponding to the reception wave is mixed with the transmission signal as shown in FIG. 2B by the mixer circuit 22, so that the frequency of the transmission signal and the reception signal is shown in FIG. 2D. A reception IF signal corresponding to the difference is obtained.

  As shown in FIG. 2D, the reception IF signal includes a frequency f1 and a frequency f2, which are frequency differences. Here, the reception IF signal has a frequency difference that changes to the frequency f1 during the transmission frequency increase period until the time t11, and a frequency difference that changes to the frequency f2 during the transmission frequency decrease period until the time t12. Furthermore, there is a frequency difference that changes to the frequency f1 during the frequency increase period from time t13. The fact that the two frequencies f1 and f2 are included means that the received wave is reflected in a space where a stationary object and a moving object are mixed, so that the received wave is both a Doppler effect of the stationary object and the moving object. This means that a frequency shift has occurred due to having received.

  Next, the radar operation of the radar apparatus 1 when the host vehicle is stopped will be described with reference to FIG.

  When a received wave reflected by a stationary object is detected in a state where the host vehicle is stopped, the triangular wave signal shown in FIG. 3A is supplied to the signal transmission unit 2 to change the frequency shown in FIG. When the transmission wave is transmitted, the signal reception unit 3 receives the reception wave having the frequency change shown in FIG. Here, the frequency difference between the transmitted wave and the received wave is such that the relative speed between the host vehicle and the stationary object is “0”, so the received wave has no frequency shift due to the Doppler effect, and the received IF signal during the transmission frequency increase period. And the frequency of the reception IF signal during the transmission frequency falling period are only the same frequency f1.

  The received IF signal is sent to the target recognizing unit 35 without being shifted in frequency by the frequency offset unit 34 because the host vehicle is not traveling. And if the difference calculation of two frequency spectra of a transmission frequency rise period and a transmission frequency fall period is performed in the target recognition part 35, a frequency difference will disappear. Thereby, in the received wave reflected from the stationary object in the stopped state, there is no signal, and the signal component for detecting the stationary object can be canceled by the target recognition unit 35.

  On the other hand, as shown in FIG. 2, the received IF signal obtained by reflection from a moving object has two frequencies f1 and f2, and the frequency offset unit 34 performs a frequency shift based on the own vehicle speed, It is supplied to the mark recognition unit 35. Therefore, by performing a difference calculation between at least the frequency before time t1 in the transmission frequency rising period shown in FIG. 2D and the frequency at time t1 to time t2 in the transmission frequency falling period, the transmission wave is generated by the moving object. A frequency shift due to reflection can be detected. That is, when reflected by a moving object, there is a frequency shift due to the Doppler effect, so that a signal based only on the moving object can be detected without being canceled by the difference calculation of the frequency spectrum.

  In other words, the relative speed of the stationary object is calculated from the own vehicle speed, a positive frequency offset corresponding to the Doppler shift amount based on the own vehicle speed is added to the reception IF signal of the transmission frequency increasing portion, and the reception IF of the transmission frequency decreasing portion is received. By adding a negative frequency offset corresponding to the Doppler shift amount based on the vehicle speed to the signal, the signal component of the stationary object is converted to the same frequency in the transmission frequency increasing part and the transmission frequency decreasing part, so that the frequency Only the signal component of the moving object is detected by spectral difference calculation.

  More specifically, as shown in FIG. 4, the received IF signal and the transmission frequency in the transmission frequency increase period, as shown in FIG. 4, the frequency spectrum of the received IF signal when the received wave from the stationary object is received with the host vehicle stopped. The received IF signal in the falling period is a signal component having substantially the same frequency. Therefore, by performing the frequency spectrum difference calculation by the target recognizing unit 35, it is possible to cancel the signal component reflected by the stationary object.

  In addition, as shown in FIG. 5, the reception IF signal in the transmission frequency increase period and the transmission frequency decrease period in the transmission frequency increase period, as shown in the frequency spectrum of the reception IF signal when the received wave from the moving object is received with the host vehicle stopped. A signal component appears at a different frequency from the received IF signal. In this example, the frequency difference between the reception IF signal during the transmission frequency increase period and the reception IF signal during the transmission frequency decrease period is twice the Doppler frequency generated at the speed of the moving object. Therefore, a large signal component can be obtained by performing a frequency spectrum difference calculation by the target recognizing unit 35.

  Furthermore, when the moving speed of the moving object is known, the frequency spectrum of the transmission frequency rising period has a frequency in the positive direction by the Doppler shift amount corresponding to the moving speed with respect to the frequency spectrum of the reception IF signal shown in FIG. When the frequency spectrum is shifted and shifted in the negative direction by the amount of Doppler shift corresponding to the moving speed, the frequency spectrum in the transmission frequency falling period is as shown in FIG. That is, the signal components of the reception IF signal in the transmission frequency increase period and the reception IF signal in the frequency decrease period have the same frequency.

  Therefore, in the radar apparatus 1 to which the present invention is applied, contrary to the case of referring to FIG. 6 described above, the received wave reflected by the stationary object is received when the moving speed of the host vehicle is known. Applicable. In other words, since the speed of the host vehicle is known, the Doppler shift amount based on the speed of the host vehicle is calculated, the frequency spectrum of the reception IF signal in the transmission frequency increase period is in the positive direction, and the reception IF in the transmission frequency decrease period By shifting the frequency spectrum of the signal in the negative direction, the frequency component reflected by the stationary object can be replaced with the same frequency in the transmission frequency increase period and the transmission frequency decrease period. Then, the target recognizing unit 35 can attenuate the frequency shift appearing by reflection on the stationary object by performing the difference calculation of the two frequency spectra.

  Further, in the radar device 1, when the host vehicle is traveling at a low speed in an urban area or when the host vehicle is stopped and many stationary objects are detected, the radar is transmitted by the target recognition unit 35. When the moving object is detected by calculating the difference between the reception IF signal during the frequency increase period and the reception IF signal during the transmission frequency decrease period, while the host vehicle is traveling at a speed higher than a predetermined speed set in advance. Does not perform the difference calculation after offsetting the Doppler shift amount, but performs the difference calculation between the frequency spectrum in the transmission frequency rising period and the frequency spectrum in the transmission frequency falling period to detect both stationary and moving objects Processing may be performed. That is, in the radar apparatus 1, when traveling at a high speed, a process for calculating a deviation of the peak value of the frequency spectrum from the frequency spectrum subjected to the frequency analysis by the FFT processing unit 32 and the frequency modulation by the triangular wave generating unit 31 is performed. Become.

[Effect of the first embodiment]
As described above in detail, according to the radar device 1 according to the first embodiment to which the present invention is applied, the frequency spectrum of the transmission frequency increase period is frequency shifted in the positive direction by the Doppler shift amount based on the own vehicle speed, By shifting the frequency spectrum of the transmission frequency falling period in the negative direction by the Doppler shift amount based on the host vehicle speed, the frequency shift reflected and generated by a stationary object having a relative speed corresponding to the host vehicle speed is defined as the transmission frequency increasing period. It can be replaced with the same frequency component in the transmission frequency falling period. Therefore, according to the radar apparatus 1, the signal component reflected by the stationary object is reduced by calculating the difference between the reception IF signal during the transmission frequency increase period and the reception IF signal during the transmission frequency decrease period, thereby reducing the moving object. The reflected signal component can be detected, and the detection efficiency of the moving object can be improved.

  Therefore, according to the radar apparatus 1, there is no need to exist on the side of a wall or the like, for example, when the vehicle is traveling at a low speed or stopped in an urban area where many stationary objects and moving objects are mixed. Even when the detection frequency of a received wave from a stationary object is high, it is possible to suppress a situation in which it is difficult to detect a moving object that moves so as to approach the host vehicle.

  Further, according to the radar apparatus 1, when the own vehicle is traveling at a low speed or stopped, the difference between the received IF signals is calculated to detect the moving object efficiently, while the own vehicle When the vehicle is traveling at high speed, both the stationary object and the moving object are detected by detecting the change in the peak value of the frequency spectrum, so that the target detection function such as ACC control is not affected. The signal transmission unit 2 can be shared when detecting only a moving object and during ACC control.

[Second Embodiment]
Next, a radar apparatus 1 according to the second embodiment will be described. In addition, about the part similar to the above-mentioned 1st Embodiment, the detailed description is abbreviate | omitted by attaching | subjecting the same code | symbol.

  As shown in FIG. 7, the radar apparatus 1 includes a beam scanning unit 41 that scans a transmission wave transmitted from the signal transmission unit 2 in the horizontal direction, and uses information from the beam scanning unit 41 to generate a frequency. It differs from the radar apparatus 1 according to the first embodiment in that the offset amount calculation unit 42 and the target recognition unit 43 are operated.

  The beam scanning unit 41 includes a mechanism capable of rotating the transmission antenna 13 in the horizontal direction, and scans the transmission wave transmission range of the transmission antenna 13 in the horizontal direction by rotating the transmission antenna 13 in the horizontal direction. Then, the beam scanning unit 41 creates transmission direction information of the transmission antenna 13 corresponding to the current rotation angle of the transmission antenna 13 and outputs it to the frequency offset amount calculation unit 42 and the target recognition unit 43.

  When the transmission direction information from the beam scanning unit 41 is input, the frequency offset amount calculation unit 42 vector-decomposes the speed information of the host vehicle in the direction indicated by the transmission direction information, and extracts the speed component in the transmission direction. The frequency offset amount calculation unit 42 calculates a Doppler shift amount based on the host vehicle speed from the speed component in the transmission direction and supplies the Doppler shift amount to the frequency offset unit 34. As a result, the frequency offset unit 34 shifts the frequency spectrum of the reception IF signal in the transmission frequency increase period in the positive direction using the supplied Doppler shift amount, and the frequency of the reception IF signal in the transmission frequency decrease period. The spectrum is frequency shifted in the negative direction and output to the target recognition unit 43.

  When the target recognizing unit 43 receives the frequency spectrum in the transmission frequency rising period and the frequency spectrum in the transmission frequency falling period from the frequency offset unit 34, the target recognition unit 43 performs the difference calculation between the frequency spectra to transmit the transmission antenna 13 A moving object existing in the direction can be detected. In addition, the target recognizing unit 43 obtains the presence / absence and distance of the moving object in the transmission direction and the relative speed of the moving object from the transmission direction information from the beam scanning unit 41, and transmits it to the ACC control unit.

  Thus, according to the radar apparatus 1 according to the second embodiment, when performing obstacle detection while scanning the transmission direction of the transmission wave, the relative speed of the stationary object and the relative speed of the moving object differ depending on the direction. Even in this case, the signal component reflected by the stationary object in the transmission direction can be reduced, and the moving object can be detected efficiently. That is, according to the radar apparatus 1, it is possible to reduce the signal component due to reflection from a stationary object in all directions where a moving object needs to be detected, and to detect the moving object more efficiently.

  Further, according to the radar apparatus 1, even when performing ACC control or the like depending on the direction, or when performing ACC control even during low-speed traveling, and when it is necessary to widen the scanning range of the transmission wave, The travel direction of the host vehicle and the transmission direction are not significantly different, and the Doppler shift amount that differs depending on the transmission direction is adjusted appropriately to reduce the signal component due to reflection on a stationary object and to detect moving objects more efficiently. Can be done well.

[Third Embodiment]
Next, a radar apparatus 1 according to the third embodiment will be described. Note that parts similar to those in the above-described embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

  As shown in FIG. 8, the radar apparatus 1 according to the third embodiment includes a movement vector calculation unit 51 that calculates the movement vector of the own vehicle that inputs the own vehicle speed information, the steering angle information, and the left and right wheel speed difference information. This is different from the radar apparatus 1 according to the second embodiment.

  The movement vector calculation unit 51 uses not only the vehicle speed from a vehicle speed sensor (not shown) but also the wheel speed information detected by the steering angle sensor and the left and right wheel speed sensors in conjunction with the steering wheel operation of the driver, The movement vector including the traveling direction is calculated. This movement vector includes not only a straight direction but also a movement vector in a direction of turning left and right.

  Accordingly, the frequency offset amount calculation unit 42 obtains the Doppler shift amount of the vehicle speed corresponding to the movement vector from the movement vector in the transmission direction from the beam scanning unit 41 and supplies the Doppler shift amount to the frequency offset unit 34.

  Accordingly, the target recognition unit 43 reduces the signal component reflected by a stationary object existing in the direction of the movement vector using the movement vector of the own vehicle speed even when the own vehicle rotates in the left-right direction. Thus, the signal component reflected by the moving object existing in the direction of the movement vector can be extracted. As a result, it is possible to accurately calculate the speed component of the host vehicle for each sending direction even when the host vehicle is traveling straight ahead, and detecting a stationary object when the host vehicle is turning at an intersection or the like. And a moving object approaching the host vehicle can be efficiently detected.

  That is, according to the radar device 1, when the host vehicle is steered, a deviation occurs between the sending direction of the radar device 1 and the traveling direction of the own vehicle, and the speed component in the sending direction of the own vehicle speed is incorrect. However, since the movement vector of the own vehicle speed is decomposed in consideration of the deviation from the vehicle center axis in the traveling direction of the own vehicle, the own vehicle speed for obtaining the Doppler shift amount can be corrected. It is possible to detect a stable moving object regardless of the traveling direction.

[Fourth Embodiment]
Next, a radar apparatus 1 according to the fourth embodiment will be described. Note that parts similar to those in the above-described embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

  As shown in FIG. 9, the radar apparatus 1 according to the fourth embodiment connects a circulator 61 and a beam scanning unit 62 to the distributor 12 of the signal transmission unit 2, and a transmission antenna and a reception antenna are connected to the beam scanning unit 62. Is different from the above-described embodiment in that a transmission / reception antenna 63 is used.

  In the above-described embodiment, the transmission azimuth axis of the transmission antenna is changed. However, the transmission / reception antenna 63 includes, for example, a transmission antenna and a reception antenna formed on the same substrate, and the substrate is simply arranged in the horizontal direction. By making it vibrate, sharing of the transmission antenna and the reception antenna and scanning of the transmission / reception direction are realized.

  In such a radar apparatus 1, when transmitting a transmission wave from the transmission / reception antenna 63, the circulator 61 supplies a transmission signal from the distributor 12 to the beam scanning unit 62, and when the reception wave is received by the transmission / reception antenna 63. Performs a switching process for supplying a reception signal from the circulator 61 to the signal reception unit 3. Thereby, the radar apparatus 1 operates the transmission / reception antenna 63 as transmission / reception common use.

  Similarly to the above-described second and third embodiments, the radar apparatus 1 supplies transmission direction information from the beam scanning unit 62 to the frequency offset amount calculation unit 64 and the target recognition unit 65, and transmits the transmission direction of the transmission wave. Based on the above, the Doppler shift amount is changed, and the target recognition unit 65 detects the moving object in the transmission direction of the transmission wave.

  As described above, according to the radar apparatus 1 according to the fourth embodiment, even when the transmission / reception antenna 63 sharing the transmission antenna and the reception antenna is used, the transmission direction of the transmission wave is scanned as described above. A moving object in the transmission direction can be detected efficiently.

  The above-described embodiment is an example of the present invention. For this reason, the present invention is not limited to the above-described embodiment, and various modifications can be made depending on the design and the like as long as the technical idea according to the present invention is not deviated from this embodiment. Of course, it is possible to change.

  That is, in the radar device 1 described above, the transmission direction of the transmission wave has been described as being forward of the host vehicle. However, the present invention is not limited to this, and the above-described effect is exhibited even when the host vehicle is behind or side of the host vehicle. Of course.

It is a block diagram which shows the structure of the radar apparatus which concerns on 1st Embodiment to which this invention is applied. It is a figure for demonstrating the process which detects only a moving object from a received wave in the radar apparatus which concerns on 1st Embodiment to which this invention is applied, Comprising: (a) is an intensity change of a triangular wave signal, (b) is a transmission wave. (C) is a figure which shows the frequency change of a received wave, (d) is a figure which shows the frequency change of a received IF signal. It is a figure for demonstrating the process using the received wave reflected by the stationary object in the radar apparatus which concerns on 1st Embodiment to which this invention is applied, Comprising: (a) is an intensity change of a triangular wave signal, (b) is transmission FIG. 4C is a diagram showing a change in frequency of a wave, FIG. 5C is a diagram showing a change in frequency of a received wave, and FIG. It is a figure which shows the frequency spectrum of the reception IF signal at the time of receiving the received wave from a stationary object in the state which the own vehicle stopped. It is a figure which shows the frequency spectrum of the reception IF signal at the time of receiving the received wave from a moving object in the state which the own vehicle stopped. In order to explain the case where the moving speed of the moving object is known, the frequency spectrum of the reception IF signal shown in FIG. 5 is shifted to the frequency spectrum of the transmission frequency rising period and the frequency spectrum of the transmission frequency falling period. FIG. It is a block diagram which shows the structure of the radar apparatus which concerns on 2nd Embodiment to which this invention is applied. It is a block diagram which shows the structure of the radar apparatus which concerns on 3rd Embodiment to which this invention is applied. It is a block diagram which shows the structure of the radar apparatus which concerns on 4th Embodiment to which this invention is applied.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Radar apparatus 2 Signal transmission part 3 Signal receiving part 4 Signal processing part 11 VCO
DESCRIPTION OF SYMBOLS 12 Divider 13 Transmission antenna 21 Reception antenna 22 Mixer circuit 23 Amplifier amplifier 31 Triangular wave generation part 32 FFT processing part 33, 42, 64 Frequency offset amount calculation part 34 Frequency offset part 35, 43, 65 Target recognition part 41, 62 Beam Scan unit 51 Movement vector calculation unit 61 Circulator 63 Transmission / reception antenna

Claims (5)

Transmitting means for performing frequency modulation according to the intensity change of the triangular wave signal and transmitting a transmission signal including a transmission frequency increase period and a transmission frequency decrease period;
A transmission unit that reflects the transmission signal transmitted from the transmission unit, receives the reflected transmission signal as a reception signal, and generates a frequency difference signal indicating a frequency difference between the reception signal and the transmission signal;
Signal processing means for detecting a moving object around the host vehicle using the frequency difference signal generated by the receiving means;
The signal processing means includes
A frequency analysis means for calculating a frequency spectrum of the frequency difference signal;
Frequency offset amount calculating means for inputting speed information of the host vehicle and calculating a frequency shift amount according to the host vehicle speed;
A frequency offset means for offsetting the frequency spectrum in the transmission frequency rising period in the positive direction by the frequency shift amount, and offsetting the frequency spectrum in the transmission frequency falling period in the negative direction by the frequency shift amount;
Target recognition for detecting a moving object based on a frequency spectrum obtained by calculating a difference between a frequency spectrum offset in the positive direction by the frequency offset means and a frequency spectrum offset in the negative direction by the frequency offset means. And a moving object detection device. The transmission means includes transmission direction scanning means for scanning the transmission direction of the transmission signal,
The frequency offset unit calculates a speed component of the host vehicle in a transmission direction of the transmission signal by the transmission direction scanning unit, and calculates a frequency shift amount corresponding to the calculated speed component. Item 4. The moving object detection device according to Item 1.   The frequency offset means detects a moving direction of the host vehicle, corrects a speed component of the host vehicle in a transmission direction of the transmission signal based on the moving direction of the host vehicle, and calculates a frequency shift amount. The moving object detection apparatus according to claim 2.   The signal processing means does not offset the frequency spectrum by the frequency offset means when the host vehicle speed is high, and the target recognition means does not cause the frequency spectrum of the transmission frequency rise period and the transmission frequency fall period to The difference calculation with a frequency spectrum is performed, and when the own vehicle speed is low or stopped, the difference calculation is performed using the frequency spectrum offset by the frequency offset means. The moving object detection device according to claim 3. The frequency offset amount calculating means calculates a frequency shift amount that cancels a frequency shift amount between the transmission signal and the reception signal generated due to a relative speed between the host vehicle and a stationary object. The moving object detection device according to any one of claims 1 to 4.

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