JP2009281928A - Radar apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a radar apparatus for adjusting a code length of a code signal according to the number of vehicles. <P>SOLUTION: The number of the vehicles is counted by processing an image captured by a camera in the running direction of the vehicle. The code length and the order of the code signal are determined based on the counted number. The code signal is generated by the determined code length and the order, and spatially emitted as electromagnetic waves. Information on an object such as a relative distance between the vehicles is calculated by calculating a correlation between the code signal and a signal received by a receiving section. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a radar apparatus, and more particularly to a radar apparatus mounted on a moving body such as a vehicle.

  As a radar device to be mounted on a moving body such as a vehicle, the time it takes to transmit a transmitted wave after receiving the reflected wave reflected by the object, and transmit the transmitted wave until receiving the reflected wave. A radar apparatus that calculates information on an object such as a relative distance and a relative speed with respect to the object based on a phase difference with a reflected wave or the like has been put into practical use. As such a radar apparatus, for example, an automotive forward warning radar apparatus (hereinafter referred to as a conventional technique) described in Patent Document 1 is cited.

In the prior art, in order to prevent the radar apparatus of the own vehicle from receiving the transmission wave transmitted from the radar apparatus of the other vehicle as a reflected wave, the erroneous identification information of the object is calculated. A signal obtained by mixing the transmission pseudo noise signal is transmitted as a transmission wave. More specifically, in the prior art, an exclusive OR of an identification code unique to a vehicle and a PN code is calculated, a carrier wave is phase-modulated with the calculated code signal, and the modulated signal is transmitted as a transmission wave. When the reflected wave is received, the prior art calculates the product of the reception PN code and the reflected wave, demodulates the identification code from the calculation result, and compares it with the identification code of the host vehicle. In the prior art, data indicating information on an object is generated only when the demodulated identification code matches the identification code of the host vehicle.
Japanese Patent Laid-Open No. 7-84035

  However, the above prior art has the following problems. In the above-described prior art, when the reflected wave of the transmission wave transmitted from the radar apparatus of the own vehicle and the transmission wave transmitted from the other vehicle are identified, the greater the number of radar apparatuses of the other vehicle that can be identified, the greater The possibility of receiving an erroneous transmission wave can be reduced. However, in order to increase the number of radar devices of other vehicles that can be identified, the information amount (number of bits) of the identification code must be increased. When a transmission wave is generated based on an identification code with a large amount of information, the power required for generation increases, and the time required to transmit the generated transmission wave once and the reflected wave of the transmission wave Each time required to receive the message becomes longer.

  Therefore, an object of the present invention is to provide a radar apparatus that can adjust the code length of a code signal in accordance with the number of other vehicles.

In order to achieve the above object, the present invention has the following features.
1st invention is a radar apparatus which measures the object which exists within a measurement range, Comprising: The imaging means which images the image within a measurement range, and within the measurement range based on the image imaged by the imaging means Counting means for counting the number of other vehicles as the number of other vehicles; code signal generating means for determining a code length based on the number of other vehicles; generating a code signal of the determined code length; and And radiating means for radiating as.

  A second invention is an invention subordinate to the first invention, comprising: a receiving means for receiving a reflected wave in which an electromagnetic wave is reflected by an object; a code signal having a code length radiated as an electromagnetic wave; Calculation means for calculating the correlation and calculation means for calculating and measuring information on the object reflecting the reflected wave based on the reflected wave whose correlation is equal to or greater than a predetermined threshold value are further provided.

  A third invention is an invention subordinate to the first invention, and the code signal generating means generates a binary M-sequence code signal as a code signal.

  A fourth invention is an invention subordinate to the third invention, wherein the code signal generation means calculates a code length capable of expressing the total number of other vehicles and the host vehicle. And an order calculation means for calculating the order for generating the M-sequence code signal having the code length calculated by the calculation means, and a shift register having the number of orders calculated by the order calculation means to generate the M-sequence code signal. M-sequence code generation means.

  A fifth invention is an invention subordinate to the first invention, and the code signal generating means generates a binary Gold sequence code signal as a code signal.

  6th invention is invention which is dependent on 5th invention, Comprising: The code | symbol signal generation means calculates the code length which can express the number which can add the number of other vehicles and the own vehicle And an order calculation means for calculating the order for generating the M-sequence code signal having the code length calculated by the calculation means, and a shift register having the number of orders calculated by the order calculation means. One M-sequence code generation means, and a Gold code generation means for generating a Gold-sequence code signal by calculating an exclusive OR of two M-sequence code signals generated by the M-sequence code generation means. .

  A seventh invention is a measurement method executed by a radar apparatus for measuring an object existing within a measurement range based on an electromagnetic wave radiated by a radiating means and a reflected wave received by a receiving means. An imaging step for capturing an image within the range, a counting step for counting the number of other vehicles existing within the measurement range based on the image captured in the imaging step, and a code length based on the number of other vehicles A code signal generating step for determining the length and generating a code signal of the determined code length, and a radiation step for radiating the code signal as an electromagnetic wave.

  An eighth invention is an invention subordinate to the seventh invention, comprising: a reception step of receiving a reflected wave in which an electromagnetic wave is reflected by an object; and a code signal having a code length radiated as an electromagnetic wave and the reflected wave A calculation step for calculating the correlation, and a calculation step for calculating and measuring information on the object reflecting the reflected wave based on the reflected wave whose launch is equal to or greater than a predetermined threshold value are further provided.

  A ninth invention is an invention subordinate to the seventh invention, and generates a binary M-sequence code signal as a code signal in the code signal generation step.

  A tenth invention is an invention dependent on the ninth invention, wherein the code signal generation step calculates a code length that can represent a total number of other vehicles and the host vehicle. An order calculation step for calculating the order for generating the M-sequence code signal having the code length calculated in the code length calculation step, and an M-sequence code in the shift register of the number of orders calculated in the order calculation step An M-sequence code generation step for generating a signal.

  The eleventh invention is an invention subordinate to the seventh invention, and in the code signal generation step, a binary Gold series code signal is generated as a code signal.

  A twelfth invention is an invention subordinate to the eleventh invention, wherein the code signal generation step calculates a code length that can represent a total number of other vehicles and the host vehicle. An order calculation step for calculating an order for generating an M-sequence code signal having the code length calculated in the code length calculation step, and an M-sequence code in a shift register of the number of orders calculated in the order calculation step An M-sequence code generation step for generating two signals, and a Gold code generation step for generating a Gold-sequence code signal by calculating an exclusive OR of the two M-sequence code signals generated in the M-sequence code generation step Including.

  According to the first invention, since the code length of the code signal radiated as an electromagnetic wave can be adjusted according to the number of other vehicles existing within the measurement range of the radar apparatus according to the present invention, one code The power required to generate the signal can be saved.

  According to the second invention, since the correlation is calculated with the code signal whose code length is adjusted according to the number of other vehicles existing within the measurement range of the radar apparatus according to the present invention, the correlation is calculated once. It is possible to reduce the time required for

  According to the third aspect of the invention, since the M-sequence code signal having a relatively high autocorrelation and a relatively low correlation with other signals is generated as the code signal, the radiation is radiated from the radar device mounted on the other vehicle. Based on the reflected wave that has received the received electromagnetic wave, it is possible to reduce the possibility of erroneously calculating the information of the object.

  According to the fourth invention, the number of shift registers for generating the M-sequence code can be changed according to the number of other vehicles existing within the measurement range of the radar apparatus according to the present invention.

  According to the fifth aspect, it is possible to generate, as a code signal, a Gold sequence code signal whose correlation with other signals is relatively lower than that of the aforementioned M sequence code signal.

  According to the sixth aspect of the invention, only by calculating the exclusive OR of two M-sequence code signals, a Gold sequence code having a correlation lower than that of the M-sequence code signal is generated. be able to.

  Further, according to the measurement method of the present invention, the same effect as the radar apparatus according to the present invention described above can be obtained.

(First embodiment)
FIG. 1 is a functional block diagram showing a functional configuration of the radar apparatus 1 according to the first embodiment. The radar apparatus 1 includes a camera 101, an object detection unit 102, a code signal generation unit 103, a transmission unit 104, a reception unit 105, a correlation processing unit 106, and an information calculation unit 107.

  The camera 101 is typically a CCD (Charge Coupled Device) camera. As shown in FIG. 2, the camera 101 is attached to a room mirror of the host vehicle so that the traveling direction of the host vehicle can be captured. The camera 101 generates image data Gd indicating an image including other vehicles existing in the traveling direction of the host vehicle. In addition, the attachment location of the camera 101 is not limited to the rearview mirror, and may be attached to any location as long as the other vehicle existing in the traveling direction of the host vehicle can be imaged. Further, the imaging range of the camera 101 may be a range in which the traveling direction of the host vehicle can be imaged, or a range in which an image within the measurement range of the radar apparatus 1 according to the present embodiment can be captured.

  The object detection unit 102 acquires the image data Gd generated by the camera 101, performs image processing on the acquired image data Gd, and thereby captures another vehicle (radar) captured in the image indicated by the image data Gd. Other vehicles existing within the measurement range of the device 1 may be extracted. Then, the object detection unit 102 counts the number of extracted other vehicles (hereinafter referred to as the number of other vehicles), and generates count data Num indicating the counted number of other vehicles. Any method may be used as the method by which the object detection unit 102 extracts other vehicles. As a specific example of the method by which the object detection unit 102 extracts another vehicle, there is another vehicle based on the contour of the other vehicle obtained by performing edge detection processing on the acquired image data Gd. There is a method of extracting each as a rectangular shape indicating a region on the image. FIG. 3 is a diagram illustrating an example of an image when the extracted rectangular shape is superimposed on the image indicated by the image data Gd acquired from the camera 101 and displayed. In the example shown in FIG. 3, four rectangular shapes are extracted by the object detection unit 102, and 4 is counted as the number of other vehicles described above.

  The code signal generation unit 103 acquires the count data Num generated by the object detection unit 102, and calculates the code length of a predetermined series of code signals based on the number of other vehicles indicated by the acquired count data Num. Then, the code signal Fs is generated with the calculated code length. More specifically, assuming that the code signal generation unit 103 is predetermined to generate a binary M-sequence code signal as the code signal Fs, the number of other vehicles indicated by the acquired count data Num is calculated. The order of the minimum code length that can be expressed by a binary M-sequence code signal is calculated. The code length is the number of pulses constituting one code signal Fs. There is a relationship shown in Equation (1) between the code length and the order of the M-sequence code.

  In Equation (1), N is the code length and k is the order. From the relationship shown in Expression (1), for example, when the code signal generation unit 103 obtains the count data Num indicating the number of other vehicles 4 as illustrated in FIG. 3, 3 is set as the code length N that can represent 4. calculate. This is because a signal generated by using the binary M-sequence code signal described above as the code signal Fs can be considered in the same way as a binary digital signal. Further, as is clear from Equation (1), the M-sequence code signal This is because the code length N of is an odd number. That is, the code length N (the number of bits in the digital signal) of a digital signal that can represent 4 is 2, but the code length N must be an odd number. The number of other vehicles 4 indicated by Num can be expressed, and 3 is calculated as the minimum odd code length N.

  In addition, since the calculated code length N is a short code length of 1 because the number of other vehicles is relatively small, and the generated code signal is not substantially a code signal, the code length N 3 may be set in advance as the lower limit of the length N. When the calculated code length N is 1, the code signal generation unit 103 may generate the code signal Fs with a code length of 3 or more, which is a preset lower limit. In addition, when generating the code signal Fs of another series, the code length N does not necessarily have to be an odd number.

  After calculating the code length N, the code signal generation unit 103 calculates the order k based on the calculated code length N and Equation (1). The order k corresponds to the number of shift registers in a known M-sequence code generator composed of a plurality of shift registers. When the order signal k is calculated, the code signal generation unit 103 generates a binary M-sequence code signal as a pulse signal by using as many shift registers as the order k from among a plurality of shift registers provided therein. . In addition, when the code length N is calculated, the code signal generation unit 103 generates information indicating the calculated code length N.

  The configuration of the code signal generation unit 103 is not necessarily limited to the one having a plurality of shift registers therein, but is the same signal as the signal generated by the M-sequence code generator configured by k shift registers. Any configuration is possible as long as it can be generated. As another specific example, a program that simulates an M-sequence code generator composed of a plurality of shift registers is stored in advance in a storage unit (not shown), and is calculated as the number of shift registers in the program. It may be a microcomputer composed of an IC, an LSI, a CPU, and the like that execute the program in the order k.

  FIG. 4 is a diagram illustrating an example of the code signal Fs generated by the code signal generation unit 103. The code signal generation unit 103 generates one code signal Fs having a time length ta determined by the code length N every time the time interval tb arrives. The time tb shown in FIG. 4 may be any time interval as long as the minimum measurement range of the desired relative distance can be obtained, and the propagation speed of the electromagnetic wave in the space and the maximum measurement range of the relative distance. It may be determined based on the time. This is because the radar apparatus 1 according to the present embodiment has a period until the receiving unit 105 receives the reflected wave reflected as the reflected signal Hs by the relative distance of the maximum measurement range of the code signal Fs radiated from the transmitting unit 104 as an electromagnetic wave. This is because the correlation processing unit 106 repeatedly calculates the correlation between the code signal Fs radiated as an electromagnetic wave and the reflected signal Hs.

  Note that the sequence of the code signal Fs generated by the code signal generation unit 103 is not limited to the M sequence, but is a Gold sequence code that is a kind of pseudo noise code (PN (Pseudo Noise) sequence code) as with the M sequence code. Or the like may be generated as the binary code signal Fs. Any method may be used as a method for generating a Gold sequence code signal. For example, a method for generating a Gold sequence code by calculating an exclusive OR of two M sequence code signals having the same code length is used. A typical example. In the present embodiment, the case where the code signal generation unit 103 generates a binary M-sequence code signal will be described as an example.

  The transmission unit 104 radiates the code signal Fs generated by the code signal generation unit 103 to the space as an electromagnetic wave every time the time interval tb arrives.

  The receiving unit 105 receives a reflected wave obtained by reflecting an electromagnetic wave radiated by the transmitting unit 104 from an object (for example, another vehicle) as a reflected signal Hs.

  The correlation processing unit 106 calculates a correlation between the code signal Fs generated by the code signal generation unit 103 and the reflected signal Hs received by the reception unit 105.

  More specifically, the correlation processing unit 106 acquires information indicating the code length N calculated by the code signal generation unit 103. Then, the correlation processing unit 106 repeatedly calculates the correlation between the code signal Fs and the reflected signal Hs received by the receiving unit 105 until the time tb elapses after the code signal Fs is emitted as an electromagnetic wave.

  When the correlation processing unit 106 determines that the reflected signal Hs of the code signal Fs has been received after the code signal Fs is emitted based on the calculated correlation, the correlation processing unit 106 generates information indicating that the reflected signal Hs has been received. At this time, the correlation processing unit 106 calculates a time interval td from when the code signal Fs is radiated to when the reflected signal Hs of the code signal Fs is received.

  More specifically, the correlation processing unit 106 uses the code length indicated by the acquired information to indicate the synchronization between one code signal Fs generated by the code signal generation unit 103 and the reflected signal Hs received by the reception unit 105. While taking N (matching the phase), the level of the signal mixed by the mixer (not shown) is calculated as a correlation. The M-sequence code signal generated as the above-described code signal Fs is a kind of signal called a pseudo noise signal in which autocorrelation is relatively high and correlation with other signals is relatively low. Therefore, the level of the signal mixed by the mixer (not shown) by the correlation processing unit 106 is a peak value (maximum value) when the code signal Fs generated by the code signal generation unit 103 is mixed with the reflected signal Hs reflected by the object. ), And when other signals are mixed as the reflected signal Hs, it becomes relatively low.

  That is, the correlation processing unit 106 determines whether or not the level of the signal obtained by mixing the code signal Fs and the reflected signal Hs with a mixer (not shown) has a peak value (maximum value), thereby generating the code signal generation unit 103. It is possible to determine whether or not the reflected signal Hs reflected by the object is received by the code signal Fs generated by the above. The correlation processing unit 106 mixes the code signal Fs generated by the code signal generation unit 103 while gradually increasing the delay amount of the time for mixing with the reflected signal Hs received by the reception unit 105. When the level of the mixed signal has a peak value (maximum value), it is determined that the reflected signal Hs of the code signal Fs has been received, and reception information Jj indicating that the reflected signal Hs has been received is generated. Further, the delay amount of the above-described time when it is determined that the reflected signal is received is calculated as the above-described time interval td. The correlation processing unit 106 not only determines whether or not the level of the signal obtained by mixing the code signal Fs and the reflected signal Hs in a mixer (not shown) has a peak value, but also determines the level of the mixed signal in advance. By determining whether or not the value is greater than or equal to the value, it may be determined whether or not the code signal Fs generated by the code signal generation unit 103 has received the reflected signal Hs reflected by the object.

  The correlation processing unit 106 gradually increases the delay amount from zero after the start timing of the time interval tb arrives, and sets the delay amount to zero when the end timing of the time interval tb arrives. Reset and continue the correlation calculation. It is preferable that the increment of 1 degree when the delay amount is gradually increased is equal to or less than half of the chip length of the code signal Fs.

  When the information calculation unit 107 acquires the reception information Jj generated by the correlation processing unit 106, the information calculation unit 107 acquires the time interval td from the correlation processing unit 106, and based on the relationship between the propagation speed of the electromagnetic wave in space and the time interval td, The relative distance from the object that reflected the reflected signal Hs that produced the peak value (maximum value) of the correlation is calculated.

  The above is description of each functional block shown in FIG. 1 of the radar apparatus 1 which concerns on this embodiment. Next, the processing of the radar apparatus 1 according to the present embodiment will be described with reference to the flowchart shown in FIG.

  In step S101, the radar apparatus 1 captures an image with the camera 101 and generates image data Gd. When the radar apparatus 1 completes the process of step S101, the radar apparatus 1 advances the process to step S102.

  In step S102, the radar apparatus 1 processes the image data Gd as described above in the object detection unit 102, and count data indicating the number of other vehicles captured in the image indicated by the image data Gd. Num is generated. When the radar apparatus 1 completes the process of step S102, the radar apparatus 1 proceeds to step S103.

  In step S103, the radar apparatus 1 acquires the count data Num by the object detection unit 102, and based on the number of other vehicles indicated by the data, the order k of the code signal Fs generated by the code signal generation unit 103 is described above. Calculate as follows. When the radar apparatus 1 completes the process of step S103, the radar apparatus 1 proceeds to step S104. In step S103, when the code length N calculated to calculate the order k is 1, the radar apparatus 1 has a predetermined lower limit code length of 3 or 3 or more as described above. The order k is calculated with the code length N.

  In step S <b> 104, the radar apparatus 1 generates the code signal Fs of the order k calculated in step S <b> 103 by the code signal generation unit 103, radiates it as an electromagnetic wave from the transmission unit 104, and simultaneously resets the delay amount of the correlation processing unit 106. When the radar apparatus 1 completes the process of step S104, the process proceeds to step S105.

  In step S105, the radar apparatus 1 performs the above-described correlation calculation in the correlation processing unit 106, and determines whether or not the reflected signal Hs reflected by the object is received in step S104. When it is determined that the received information has been received, the reception information Jj is generated. When the radar apparatus 1 completes the process of step S105, the radar apparatus 1 proceeds to step S106.

  In step S106, when the radar apparatus 1 acquires the reception information Jj from the correlation processing unit 106, the radar apparatus 1 further acquires the time interval td calculated by the correlation processing unit 106, and calculates the relative distance from the target object. Calculate as When the radar apparatus 1 calculates the relative distance to the object, the radar apparatus 1 generates object data indicating the calculated information. When the radar apparatus 1 completes the process of step S106, the radar apparatus 1 advances the process to step S107.

  In step S107, the radar apparatus 1 determines whether or not the time tb has elapsed since the code signal Fs was radiated as an electromagnetic wave in step S104. When the radar apparatus 1 determines in step S107 that the time tb has elapsed, the radar apparatus 1 returns the process to step S101. On the other hand, when the radar apparatus 1 determines in step S107 that the time tb has not elapsed, the radar apparatus 1 returns the process to step S105.

  The above is description of the process of the radar apparatus 1 which concerns on this embodiment. Next, effects obtained by the radar apparatus 1 according to the present embodiment will be described with reference to FIG.

  FIG. 6 is a diagram comparing a code signal radiated into the space as an electromagnetic wave by the radar apparatus 1 according to the present embodiment and a code signal having a predetermined code length repeatedly radiated into the space as an electromagnetic wave according to the prior art. It is. As shown in FIG. 6, the code length of the code signal radiated into the space for the first time is 7 regardless of whether the code signal is generated by the radar apparatus 1 or the conventional technique. The code signal radiated to the space for the second time is generated and radiated with the code length 3 by the radar apparatus 1 performing the above-described processing, whereas the code signal is radiated for the first time in the prior art. A code signal having the same code length 7 as the code signal is radiated.

  The radar apparatus 1 according to the present embodiment counts the number of other vehicles based on the image captured by the camera 101, and adjusts the code length N of the code signal according to the counted number of other vehicles. Therefore, according to the radar apparatus 1 according to the present embodiment, the second code signal whose code length is shorter by 4 than the first code signal can be radiated as an electromagnetic wave, as is apparent from FIG. Compared with the prior art, power for generating one code signal can be saved. Moreover, according to the radar apparatus 1 according to the present embodiment, the transmission time and reception time of one code signal can be shortened because the code length of one code signal is adjusted according to the number of other vehicles. The time required for the correlation processing unit 106 to calculate the correlation once can be shortened.

  In addition, the radar apparatus 1 according to the present embodiment generates an M-sequence code signal as the code signal Fs and calculates a correlation with the reflected signal, so that an electromagnetic wave radiated from another radar apparatus or noise is reflected on the reflected signal. The correlation is low when it is received as Hs, and the correlation is high only when the electromagnetic wave radiated from the transmission unit 104 of the radar apparatus 1 according to the present embodiment is received as the reflected signal Hs. That is, the radar apparatus 1 according to the present embodiment determines whether or not the correlation has a peak value (maximum value), and thereby reflects the electromagnetic wave radiated from another radar apparatus existing within the measurement range as the reflected signal Hs. As a result, it is possible to reduce the possibility of calculating incorrect information on the object.

  Note that the radar apparatus 1 according to the present embodiment may radiate electromagnetic waves in a frequency band called millimeter waves from the transmission unit 104. Further, the radar apparatus 1 according to the present embodiment may radiate electromagnetic waves in a wide frequency band called UWB (Ultra Wide Band) from the transmission unit 104.

  In the description of the first embodiment described above, the case where the radar apparatus 1 radiates a binary code signal as a pulse signal and measures the relative distance to the object has been described as an example. However, the radar apparatus 1 according to the present invention can be applied not only to the relative distance but also to a radar apparatus that calculates the relative speed with respect to the object as information on the object based on the shift amount of the Doppler shift.

  When the radar apparatus 1 measures the relative velocity with respect to the object, a modulation signal obtained by modulating a reference signal having a predetermined frequency with a code signal is radiated from the transmission unit 104 in order to calculate the shift amount of the Doppler shift. . Any method may be used to modulate the reference signal. For example, when the reference signal is modulated with a binary code signal such as an M-sequence code signal, ASK (Amplitude Shift Keying), FSK (Frequency) The reference signal may be modulated by a technique such as Shift Keying) or BPSK (Binary Phase Shift Keying). In this case, the correlation processing unit 106 calculates the correlation between the modulation signal and the reflected signal instead of the code signal as described above.

  Then, when the information calculation unit 107 acquires information indicating that the reflection signal has been received from the correlation processing unit 106, the information calculation unit 107 correlates the above-described time interval, the reflection signal received at the time interval, and the reflection signal. The modulation signal used for the calculation is acquired from the correlation processing unit 106. The information calculation unit 107 calculates the relative distance from the object that reflected the reflection signal based on the relationship between the acquired time interval and the propagation speed of the electromagnetic wave in the space. Furthermore, the information calculation unit 107 is configured to detect an object that reflects the reflected signal based on a shift amount of Doppler shift obtained by performing FFT (Fast Fourier Transform) processing based on the acquired modulated signal and reflected signal. The relative speed of is calculated. When the radar apparatus 1 measures the relative speed with respect to the object, a reference signal having a predetermined frequency is modulated with a code signal and radiated to the space. Therefore, the electromagnetic wave radiated to the space is an electromagnetic wave having a phase. The information calculation unit 107 can calculate the shift amount of the Doppler shift by performing an FFT process.

  In addition, any known method may be used as a method for synchronizing the transmission signal and the reflected signal or synchronizing the modulated signal and the reflected signal when the correlation processing unit 106 calculates the correlation. As a specific example, the correlation between the code signal and the reflected signal or the correlation between the modulated signal and the reflected signal may be calculated by a conventionally known technique such as a matched filter.

  In the first embodiment, the method of calculating information on an object using a pulse signal, that is, the method applicable to the pulse pair method or the pulse Doppler method has been described as an example. However, the method of calculating the object information by the radar apparatus 1 according to the present invention is not limited to the pulse pair method or the pulse Doppler method for calculating the object information using the pulse signal, and the frequency of the reference signal is periodically changed. Needless to say, the present invention is also applicable to a method for calculating information on an object using continuous signals having a continuous waveform, such as an FM-CW method in which information on an object is calculated by changing to the above.

  The radar apparatus 1 according to the present invention can also be applied to a radar apparatus that calculates a horizontal angle where the object exists in addition to the relative distance and relative speed with the object as information on the object. When the radar apparatus 1 according to the present invention calculates the horizontal angle at which the object exists, at least two receiving units 105 are arranged in the horizontal direction at predetermined intervals. Then, based on the phase difference or level difference calculated by radiating the above-mentioned modulated signal as an electromagnetic wave from the transmitting unit 104 and performing FFT processing or the like on each reflected signal received by the two receiving units 105. Thus, the angle in the horizontal direction where the object exists may be calculated. The method of calculating the horizontal angle where the object exists based on the phase difference is known as the phase comparison monopulse method, and the method of calculating the horizontal angle where the object exists based on the level difference is the amplitude This is known as a comparative monopulse method.

  In the first embodiment, the code signal is generated with the code length N calculated each time the code signal is emitted as an electromagnetic wave. However, the code signal with the same code length N or the code signal with the same pattern is used. May be generated a predetermined number of times, and a new code signal may be generated with a newly calculated code length N.

  In the above-described processing of the radar apparatus 1, predetermined program data stored in a storage device (ROM, RAM, hard disk, etc.) capable of executing the above-described processing procedure is interpreted and executed by a CPU or a microcomputer. It may be realized with. The CPU may be a CPU constituting an ECU (Electric Control Unit) mounted on a moving body such as an automobile. In this case, the program data may be introduced into the storage device via the storage medium, or may be directly executed from the storage medium. The storage medium may be a semiconductor memory such as a ROM, a RAM, or a flash memory, a magnetic disk memory such as a flexible disk or a hard disk, an optical disk memory such as a CD-ROM, a DVD, or a BD, and a memory card. Each functional configuration of the radar apparatus 1 described above may be realized by an electronic circuit. Furthermore, the functional configuration of the radar apparatus 1 described above may be realized by appropriately combining an electronic circuit, a CPU, a microcomputer, and the like.

  Further, the camera 101 described above may generate the image data Gd as an analog signal or a digital signal. Then, when the acquired image data Gd is an analog signal, the object detection unit 102 may perform the above-described processing with the analog signal if possible, or convert it to a digital signal with an AD converter (not shown). The processing described above may be performed. Further, each of the correlation processing unit 106 and the information calculation unit 107 may perform the above-described processing as an analog signal if possible, or may be converted into a digital signal by an AD converter (not shown) and then described above. May be processed.

  Although the present invention has been described in detail above, the above description is merely an example of the present invention in all respects and is not intended to limit the scope thereof. It goes without saying that various improvements and modifications can be made without departing from the scope of the present invention.

  ADVANTAGE OF THE INVENTION According to this invention, the radar apparatus which can adjust the code length of a code signal according to the number of other vehicles can be provided, for example, it is useful for the radar apparatus etc. which are mounted in moving bodies, such as a vehicle.

Functional block diagram of the radar apparatus according to the first embodiment The figure explaining an example of the attachment location of the camera in 1st Embodiment. The figure explaining an example of the method of extracting another vehicle The figure explaining an example of the code signal which concerns on 1st Embodiment The flowchart which shows the process of the radar apparatus which concerns on 1st Embodiment. The figure which contrasts the code signal in 1st Embodiment with the code signal in a prior art.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Radar apparatus 101 Camera 102 Object detection part 103 Code signal generation part 104 Transmission part 105 Reception part 106 Correlation processing part 107 Information calculation part

Claims (12)

A radar device for measuring an object existing within a measurement range,
Imaging means for capturing an image within the measurement range;
Counting means for counting the number of other vehicles existing within the measurement range as the number of other vehicles based on the image captured by the imaging means;
A code signal generating means for determining a code length based on the number of other vehicles and generating a code signal of the determined code length;
A radar apparatus comprising: radiation means for radiating the code signal as an electromagnetic wave. Receiving means for receiving a reflected wave reflected by the object by the electromagnetic wave;
A computing means for computing a correlation between the reflected signal and the code signal of the code length radiated as the electromagnetic wave;
2. The radar according to claim 1, further comprising: a calculation unit configured to calculate and measure information of the object that has reflected the reflected wave based on the reflected wave having the correlation equal to or greater than a predetermined threshold value. apparatus.   The radar apparatus according to claim 1, wherein the code signal generation unit generates a binary M-sequence code signal as the code signal. The code signal generating means includes
Code length calculating means for calculating a code length capable of expressing the total number of the other vehicle number and the own vehicle;
Degree calculating means for calculating the order for generating the M-sequence code signal having the code length calculated by the calculating means;
The radar apparatus according to claim 3, further comprising: an M-sequence code generation unit configured to generate the M-sequence code signal with a shift register of the order number calculated by the order calculation unit.   The radar apparatus according to claim 1, wherein the code signal generation unit generates a binary Gold series code signal as the code signal. The code signal generating means includes
Code length calculating means for calculating a code length capable of expressing the total number of the other vehicle number and the own vehicle;
Degree calculating means for calculating the order for generating the M-sequence code signal having the code length calculated by the calculating means;
M-sequence code generation means for generating two M-sequence code signals by the shift register of the order number calculated by the order calculation means;
The Gold code generation means for generating the Gold sequence code signal by calculating an exclusive OR of the two M sequence code signals generated by the M sequence code generation means. Radar device. A measurement method executed by a radar apparatus that measures an object existing within a measurement range based on an electromagnetic wave radiated by a radiation unit and a reflected wave received by a reception unit,
An imaging step of imaging an image within the measurement range;
A counting step of counting the number of other vehicles existing within the measurement range as the number of other vehicles based on the image captured in the imaging step;
A code signal generation step of determining a code length based on the number of other vehicles and generating a code signal of the determined code length;
And a radiation step of radiating the code signal as an electromagnetic wave. A reception step of receiving a reflected wave reflected by the object by the electromagnetic wave;
An operation step of calculating a correlation between the code signal of the code length radiated as the electromagnetic wave and the reflected wave;
The measurement according to claim 7, further comprising: a calculation step of calculating and measuring information on the object that reflects the reflected wave based on the reflected wave that is equal to or greater than a predetermined threshold value for the first publication. Method.   The measurement method according to claim 7, wherein in the code signal generation step, a binary M-sequence code signal is generated as the code signal. The code signal generation step includes:
A code length calculating step of calculating a code length capable of expressing the total number of the other vehicle number and the host vehicle;
An order calculating step for calculating an order for generating the M-sequence code signal having the code length calculated in the code length calculating step;
The measurement method according to claim 9, further comprising: an M-sequence code generation step of generating the M-sequence code signal with a shift register of the number of orders calculated by the order calculation step.   The measurement method according to claim 7, wherein in the code signal generation step, a binary Gold series code signal is generated as the code signal. The code signal generation step includes:
A code length calculating step of calculating a code length capable of expressing the total number of the other vehicle number and the host vehicle;
An order calculating step for calculating an order for generating the M-sequence code signal having the code length calculated in the code length calculating step;
An M-sequence code generation step of generating two of the M-sequence code signals by the shift register of the order number calculated in the order calculation step;
The Gold code generation step of generating the Gold sequence code signal by calculating an exclusive OR of the two M sequence code signals generated in the M sequence code generation step. Measuring method.

Images