JP2019045365A - Radar device - Google Patents

Abstract

To provide a radar device that does not need an expensive circuit and the like and prevents peaks of two-dimensional FFT results of a stationary object which is an object in the vicinity and a preceding vehicle from overlapping with each other by folding back of relative speed generated due to the restriction of a repetition frequency of chirp waves.SOLUTION: A control calculator 11 estimates relative speed of a roadside stationary object from its own vehicle speed and changes a repetition cycle of a transmission wave from a transmitter 12 so that a folded frequency does not overlap with a frequency of a preceding vehicle.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a radar device.

  Conventionally, in order to detect an object in the vicinity of the host vehicle as shown in Patent Document 1, there is a radar apparatus that obtains information on distance, speed, and direction from the object by transmitting radio waves and receiving reflected waves from the object. It is used in a collision damage reduction brake system that reduces damage caused when an own vehicle collides with an obstacle ahead, and an adaptive cruise control system that follows a vehicle ahead.

There are various types of methods for measuring the distance and velocity of a radar device, but there is known an FCM (Fast Chirp Modulation) method of repeatedly transmitting a chirp wave that continuously increases or decreases the frequency.
In the FCM method, the distance to an object is calculated from the frequency difference between the transmission wave of each chirp wave and the reception wave. Further, the phase of the frequency of the calculated distance is measured for each of the repeatedly transmitted chirp waves, and the relative speed is obtained by obtaining the rotational speed of the phase, that is, the frequency.
In practice, the transmit wave and the receive wave of each chirp wave are mixed, and the beat signal that has passed through the band pass filter is frequency converted by the first fast Fourier transform (hereinafter referred to as FFT) processing, and One FFT result is arranged for each frequency, and the second FFT processing is performed for each frequency. By two-time FFT processing, two-dimensional FFT results of the first frequency axis corresponding to the distance R and the second frequency axis corresponding to the relative velocity V as shown in FIG. 7 are obtained. The peak position of this two-dimensional FFT result corresponds to the distance R and the velocity V of the object.

The measurement range of the relative velocity is determined by the repetition period of the chirp wave, and the smaller the repetition period, the wider the measurement range of the relative velocity.
If the repetition period of the chirp wave is not sufficiently short, the relative velocity measurement range may be narrower than the desired measurement range, and for an object with a relative velocity exceeding the measurement range, the frequency folded in the measurement range is obtained Will be That is, the relative velocity obtained by the two-dimensional FFT can not be determined whether it is the relative velocity due to the folded frequency in the desired measurement range, and has an ambiguity of the relative velocity.

In Patent Document 1, sampling is performed at high speed so that return of relative speed does not occur in a normal speed range in which a vehicle travels.
In Patent Documents 2 and 3, relative velocity folding is permitted, and in order to resolve an ambiguity corresponding to the relative velocity, the repetition period of the chirp wave is switched every measurement period, and measurement one or more previous measurement periods earlier The ambiguity of the relative velocity is resolved by comparing it with the measurement result of the relative velocity of the cycle.

JP 2011-526370 gazette Japanese Patent Application Publication No. 2013-513093 JP, 2017-58291, A

In Patent Document 1, there is a problem that it is necessary to use an expensive AD (Analog to Digital) converter in order to speed up sampling.
In Patent Documents 2 and 3, although the relative velocity ambiguity can be solved, since the relative velocity folding itself occurs, when there are objects of two relative velocities which are equidistant and have different relative velocity, it has a relative velocity which does not occur. There is a problem that a peak due to an object and a peak due to an object having a relative velocity at which aliasing occurs overlap and become one peak.

  For example, as shown in FIG. 5, a host vehicle 500 equipped with a radar device whose relative speed range which can be measured without ambiguity is +60 km / h to −60 km / h is 120 km / h of the road speed as shown in FIG. When traveling following the leading vehicle 501, the relative velocity of the roadside stop object 502, which is a surrounding object, is -120 km / h. In such a case, since the relative velocity is -60 km / h or less, a turnaround of the relative velocity occurs, and a peak appears at the same position as the peak of the relative velocity 0 km / h. In addition, the relative speed of the leading vehicle 501 during tracking is approximately 0 km / h. When the distance between the stop object 502 and the preceding vehicle 501 is substantially the same (t = T), as shown in FIG. 8, the peaks of the two-dimensional FFT result are at the same position. turn into. In the case where the stop 502 is present alone, the overlapping of the two peaks is temporary, so this is not a serious problem, but as shown in FIG. 6, there are guardrails on the roadside, that is, guardrails. In the case where the pillars of the road exist continuously as the roadside stop object 502, as shown in FIG. 9, the peak due to the stop object 502 and the peak due to the preceding vehicle 501 overlap one after another as shown in FIG. In particular, when the leading vehicle 501 has a small radar reflection cross section (hereinafter referred to as RCS) such as a two-wheeled vehicle and the stopping object RCS is larger, the peak due to the preceding vehicle 501 is buried in the peak due to the stopping object 502. Even if it can not be detected, or even if it can be detected, the accuracy of the angle measurement process calculated based on the amplitude and phase of the peak may deteriorate.

  The present invention is intended to solve the problems as described above, and does not require an expensive circuit, etc., and the return of the relative velocity generated by the restriction of the repetition period of the chirp wave makes two-dimensional It is an object of the present invention to obtain a radar apparatus in which the peaks of the FFT result do not overlap.

  In the radar apparatus according to the present invention, the distance between the transmitter and the receiver, the receiver for receiving the reflected wave from the surrounding objects, and the reception data of the receiver are frequency analyzed to determine the distance and relative velocity to the surrounding objects. For an object having a relative velocity that is calculated and that is a frequency outside the analysis range of frequency analysis corresponding to the relative velocity, the control computing device is provided with a control computing device that computes the relative velocity from the folded frequency. It is determined whether the first frequency of the relative velocity at which aliasing occurs and the second frequency of the relative velocity at which aliasing does not overlap overlap, and the first frequency and the second frequency may overlap. If there is, the transmitter's transmission cycle is changed so that the frequency at which the object with relative velocity at which aliasing occurs does not overlap with the frequency of the object at which aliasing does not occur.

  According to the radar device of the present invention, it is determined whether or not the first frequency of the object at the relative velocity at which aliasing occurs and the second frequency of the object at the relative velocity at which aliasing does not occur overlap. When there is a possibility that the second frequency and the second frequency overlap, the transmission frequency is changed so that the frequency at which the object at the relative velocity at which the return occurs is not overlapped with the frequency of the object at which the return does not occur. By changing the repetition period of the chirp accordingly, it is possible to prevent the peak due to the stopping object from overlapping with the peak due to the preceding vehicle, and it becomes possible to accurately detect the preceding vehicle.

It is a block diagram showing a radar installation which is Embodiment 1 of this invention. It is a block diagram which shows the structure of the control arithmetic unit in the radar apparatus which is Embodiment 1 of this invention. It is a figure which shows the flow of the data of a modulation pattern of a FCM system, an observation signal (digital voltage data) from a receiving signal, and a two-dimensional FFT result. It is a flowchart for demonstrating the repetition period selection process of a chirp in the control calculator of the radar apparatus which is Embodiment 1 of this invention. It is a figure showing the state where a self-vehicle follows a preceding car and there is one stop thing on the road shoulder. It is a figure which shows the state which the own vehicle follows a preceding vehicle and there exist several stop objects which continued on the road shoulder. It is a figure which shows the example of a two-dimensional FFT result in case one detected object whose relative velocity is 0 exists. FIG. 8 is a diagram showing an example in which there is one detected object with a relative velocity of 0 and one object that has a high relative velocity and is folded back and the peak of the two-dimensional FFT result overlaps at time t = T. It is a figure which shows the example in which the relative velocity is large, and one to-be-detected object with a relative velocity of 0 exists, and two or more objects which are return | surroundings exist continuously. It is a figure which shows the relationship of a true relative velocity and the observed relative velocity.

Embodiment 1
FIG. 1 is a block diagram showing a radar device 1 according to a first embodiment of the present invention.
As shown in FIG. 1, the radar device 1 includes a control computing unit 11, a transmitter 12, a receiver 13, an analog-to-digital converter 14, and a memory 15.

The control computing unit 11 controls each part of the radar device 1 and calculates the distance to the target object and the velocity using digital data stored in a memory 15 described later.
The control computing unit 11 is configured by, for example, a one-chip microcomputer having a CPU (Central Processing Unit) function or a PLD (Programmable Logic Device) such as an FPGA (Field-Programmable Gate Array). The details of the control computing unit 11 will be described later.

  The transmitter 12 generates a desired voltage waveform at a timing controlled by a control unit 111 of a control operation unit 11 (see FIG. 2) described later, a voltage control oscillator 122, a distribution circuit 123, and an amplification circuit 124. , Antenna for transmission 125.

  The receiver 13 includes a receiving antenna 131, a mixer 132, an amplifier circuit 133, and a filter circuit 134.

  The analog-to-digital converter 14 is a converter that receives the observation signal voltage from the receiver 13 and converts it into digital voltage data at a timing controlled by a control unit 111 (see FIG. 2) of the control computing unit 11 described later. The converted digital voltage data is output to the memory 15.

  The memory 15 is digital voltage data output from the analog-to-digital converter 14 at a timing controlled by a control unit 111 (see FIG. 2) of the control operation unit 11 described later, spectrum and peak data output from the control operation unit 11 It is a circuit for storing the vehicle speed data of the vehicle from the vehicle side ECU (Engine Control Unit) 20, and is a RAM (Random Access Memory) capable of writing and reading data.

Next, details of the control computing unit 11 will be described with reference to FIG. 2 which is a functional configuration diagram of the control computing unit 11.
As shown in FIG. 2, the control computing unit 11 includes a control unit 111, a first distance direction frequency analysis unit 112a, a second distance direction frequency analysis unit 112b, a first velocity direction frequency analysis unit 113a, a second Speed direction frequency analysis unit 113b, first peak detection unit 114a, second peak detection unit 114b, first peak data generation unit 115a, second peak data generation unit 115b, first distance / temporary velocity calculation unit 116a, a second distance / provisional velocity calculation unit 116b, and a distance / velocity calculation unit 117, each of which is configured of, for example, a program operating on a one-chip microcomputer or a logic circuit on an FPGA.

  The control unit 111 includes a voltage generation circuit 121 of the transmitter 12, an analog-to-digital converter 14, a memory 15, and a first distance frequency analysis unit 112a and a second distance frequency analysis unit 112b in the control computing unit 11. Speed direction frequency analysis unit 113a, second speed direction frequency analysis unit 113b, first peak detection unit 114a, second peak detection unit 114b, first peak data generation unit 115a, second peak data generation It controls the operation timings of the unit 115b, the first distance / temporary velocity calculation unit 116a, the second distance / temporal velocity calculation unit 116b, the distance / velocity calculation unit 117, etc. The chirp repetition timing of the generation circuit 121 is determined.

  The first distance direction frequency analysis unit 112a and the second distance direction frequency analysis unit 112b read the digital voltage data stored in the memory 15 at the timing controlled by the control unit 111, and perform the first FFT, It is output to the memory 15.

  The first velocity direction frequency analysis unit 113a and the second velocity direction frequency analysis unit 113b are controlled by the control unit 111, respectively, and one distance direction frequency analysis unit 112a stored in the memory 15 and the second The first FFT result corresponding to the distance direction which is the output of the distance direction frequency analysis unit 112b is read, the second FFT is performed, and the two-dimensional FFT result corresponding to the distance direction and the velocity direction is output to the memory 15 It is.

  The first peak detection unit 114a and the second peak detection unit 114b are controlled by the control unit 111, respectively, the first velocity direction frequency analysis unit 113a stored in the memory 15, and the second velocity direction frequency. It reads out the two-dimensional FFT result corresponding to the distance direction and the velocity direction which is the output of the analysis unit 113b, and detects the detection threshold sequentially calculated from the power of the two-dimensional FFT result, or The power of the dimensional FFT results is compared, and a spectrum that is larger and larger than the detection threshold is detected as a peak, and the distance direction frequency and the velocity direction frequency of the peak are detected by the first peak data generation unit 115a; Output to the peak data generation unit 115b.

  The first peak data generation unit 115a and the second peak data generation unit 115b are detected by the first peak detection unit 114a and the second peak detection unit 114b at timings controlled by the control unit 111, respectively. The distance direction frequency and the velocity direction frequency of the peak are input, the distance is calculated from the distance direction frequency, and output to the memory 15 as peak data consisting of the distance and the velocity direction frequency.

The first distance / temporary velocity calculation unit 116 a and the second distance / temporal velocity calculation unit 116 b control the first peak data generation unit 115 a stored in the memory 15 at the timing controlled by the control unit 111, and The peak data which is the output of the peak data generation unit 115b of 2 is read out, the distance is calculated by multiplying the frequency in the distance direction by a predetermined coefficient, and the provisional velocity is calculated by multiplying the frequency in the velocity direction by a predetermined coefficient It is output to 15.
The reason why the speed is assumed to be a temporary speed is that the ambiguity of aliasing is not resolved.

  The distance / velocity calculation unit 117 reads the distance / provisional velocity which is the output of the first distance / provisional velocity calculation unit 116 a stored in the memory 15 and the second distance / proportional velocity calculation unit 116 b, and the control unit 111 controls At the correct timing, calculate the speed without distraction and ambiguity.

  Next, the operation of the radar device 1 configured as described above will be described with reference to FIG. 1, FIG. 2, and FIG.

  In the radar device 1, first, the control unit 111 of the control computing unit 11 estimates the relative velocity of the stationary object as −Vs from the own vehicle velocity Vs of the own vehicle stored in the memory 15, and from the relative velocity −Vs of the stationary object Selection of repetition periods of first and second chirps described later is performed.

  Next, at the timing controlled by the control unit 111 of the control computing unit 11, the voltage generation circuit 121 generates a predetermined first modulation voltage for transmission signal at the repetition cycle of the above-mentioned selected chirp, and the voltage control oscillator 122 Output.

The voltage control oscillator 122 outputs to the distribution circuit 123 transmission signals (chirp waves of the first transmission signal) 301 a to 301 c whose frequency changes according to the first transmission signal modulation voltage.
The distribution circuit 123 distributes and outputs the transmission signal input from the voltage control oscillator 122 to the amplification circuit 124 and the mixer 132.
The amplification circuit 124 amplifies the transmission signal input from the distribution circuit 123 and outputs 125 to the transmission antenna, and the transmission antenna 125 radiates the amplified transmission signal input from the amplification circuit 124 into space as a radio wave Do.

Next, the radio wave radiated from the transmitter 12 to the space is reflected and scattered by an object that reflects the radio wave present around the radar device 1.
Of the radio waves reflected and scattered by the object reflecting the radio waves present around the radar device 1, the radio waves returned to the radar device 1 become reception signals 302a to 302c by the receiving antenna 131, and are output to the mixer 132 Ru.
The mixer 132 mixes (mixes) the reception signals 302a to 302c from the reception antenna 131 and the transmission signals 301a to 301c from the distribution circuit 123 of the transmitter 12 to generate a mixed signal, and the amplification circuit 133 Output to
The amplification circuit 133 amplifies the mixed signal input from the mixer 132 and outputs the mixed signal to the filter circuit 134. The filter circuit 134 suppresses unnecessary frequency components from the amplified mixed signal input from the amplification circuit 133, The observation signal is output to the analog-to-digital converter 14.

  Next, the analog-to-digital converter 14 converts the observation signal input from the receiver 13 into digital voltage data 303a to 303c at the timing controlled by the control unit 111, and outputs the digital voltage data 303a to 303c to the memory 15. The observation signals (digital voltage data) 303 a to 303 c input from the analog-to-digital converter 14 are stored at the timing controlled by

  The first distance direction frequency analysis unit 112a reads observation signals (digital voltage data) 303a, 303b, and 303c for the entire period of one chirp wave stored in the memory 15 at the timing controlled by the control unit 111. Perform FFT. Furthermore, the complex spectrum 304a, 304b, 304c in which the discrete frequency of the FFT result corresponds to the distance is obtained and output to the memory 15. The memory 15 outputs the complex spectrum 304a, 304b, 304c in which the discrete frequency corresponds to the distance. Remember.

In the first velocity direction frequency analysis unit 113a, at the timing controlled by the control unit 111, the complex spectrum 304a in which the discrete frequency output from the first distance direction frequency analysis unit 112a stored in the memory 15 corresponds to the distance, 304b and 304c are read out for all repeated chirp waves, and FFT is performed on a complex spectrum of discrete frequencies corresponding to the same distance to obtain a power spectrum 305a and 305b and 305c whose discrete frequencies correspond to velocity.
That is, power spectra 305a to 305c are output to the memory 15 as two-dimensional FFT results in the distance direction and the velocity direction, and the memory 15 stores two-dimensional FFT results corresponding to the distance direction and the velocity direction.

  The first peak detection unit 114a reads out a two-dimensional FFT result corresponding to the distance direction and the velocity direction which is the output of the first velocity direction frequency analysis unit 113a stored in the memory 15 at the timing controlled by the control unit 111. By comparing the power of the two-dimensional FFT result with the detection threshold sequentially calculated from the power of the two-dimensional FFT result or the preset detection threshold and the power of the two-dimensional FFT result; Is detected as a peak, the distance direction discrete frequency and the velocity direction discrete frequency of the peak are obtained, and are output to the first peak data generation unit 115a. Here, it is assumed that the number of detected peaks is N_1.

  In the first peak data generation unit 115a, at the timing controlled by the control unit 111, the principle of the FMCW (Frequency Modulated Continuous Wave) radar from the distance direction discrete frequency F_1 [k_1] {k_1 = 1 to N_1} of the detected peak Based on the equation, the distance Dst_1 [k_1] {k_1 = 1 to N_1} is calculated by the following equation (1), where C is the velocity of the radio wave, T_1 is the modulation time width of the transmission signal, and B_1 is the modulation frequency width of the transmission signal. Do.

Dst_1 [k_1] = (C × T_1 × F_1 [k_1]) / (2 × B_1) {k_1 = 1 to N_1} (1)

  Peak data consisting of the distance Dst_1 [k_1] {k_1 = 1 to N_1} and the velocity direction discrete frequency Fv_1 [k_1] {k_1 = 1 to N_1} is output to the memory 15, and the memory 15 generates the first peak data. Store as data.

FIG. 10 is a diagram showing the relationship between the true relative velocity and the observed (generated aliasing) relative velocity.
As shown in FIG. 10, P_1 is the maximum number of times of relative velocity return within the relative velocity detection range determined in advance, and Vr_1 is the relative velocity at which the first return occurs.
The first distance / temporary velocity calculation unit 116a reads out the first peak data stored in the memory 15, and at a timing controlled by the control unit 111, the velocity direction discrete frequency Fv_1 [k_1] {k_1 = 1 to N_1}. From the above, the provisional velocity Vt_1 [k_1] [m_1] {k_1 = 1 to N_1, m_1 = −P_1 to P_1} is calculated by the following equation (2).

Vt_1 [k_1] [m_1] = (C × Fc_1) / (2 × Fv_1 [k_1]) + Vr_1 × m_1 (2)

  The temporary object data consisting of the distance Dst_1 [k_1] {k_1 = 1 to N_1} and the provisional velocity Vt_1 [k_1] [m_1] {k_1 = 1 to N_1, m_1 = −P_1 to P_1} is output to the memory 15, Stores the temporary object data as first temporary object data (temporary velocity).

Next, at the timing controlled by the control unit 111 of the control computing unit 11, the voltage generation circuit 121 generates a predetermined second modulation voltage for transmission signal at the repetition cycle of the above-mentioned selected chirp, to the voltage control oscillator 122. It is output.
Hereinafter, in the second distance direction frequency analysis unit 112b, the second velocity direction frequency analysis unit 113b, the second peak detection unit 114b, the second peak data generation unit 115b, and the second distance / temporary velocity calculation unit 116b. The first distance direction frequency analysis unit 112a, the first velocity direction frequency analysis unit 113a, the first peak detection unit 114a, the first peak data generation unit 115a, and the first distance / temporary velocity calculation unit 116a. And the memory 15 stores the second temporary object data (temporary velocity).

  From the first temporary object data and the second temporary object data stored in the memory 15, the distance / velocity calculation unit 117 sets a group of temporary objects satisfying the conditions of the following two expressions, expressions (3) and (4) Extract

  | Dst_1 [k_1] [m_1] -Dst_2 [k_2] [m_2] | <Dth (3)

  | Vt_1 [k_1] [m_1] -Vt_2 [k_2] [m_2] | <Vth (4)

  For the extracted temporary object set, the distance and the relative velocity are calculated by the following two equations, Equations (5) and (6), and are stored in the memory 15 as the distances D [q] and V [q] of the objects. Remember. Here, q is the number of sets of extracted temporary objects.

  D [q] = (Dst_1 [k_1] [m_1] + Dst_2 [k_2] [m_2]) / 2 (5)

  V [q] = (Vt_1 [k_1] [m_1]]-Vt_2 [k_2] [m_2]) / 2 (6)

  Next, selection of the repetition period of the chirp in the control unit 111 of the control computing unit 11 described above will be described using the flowchart of FIG.

  First, the host vehicle speed Vs stored in the memory 15 in step ST1 is input. It is assumed that the own vehicle speed is transmitted from the vehicle side ECU 20 at a constant cycle and stored in the memory 15 through the in-vehicle network or the like.

  Next, in step ST2, whether the difference between the relative velocity-Vs of the stationary object which is the peripheral object and the relative velocity V1 which is the first turn in the first distance / temporary velocity calculation unit 116a is smaller than a predetermined value ΔV1 It is determined whether or not. In the case of YES, since the peak due to the stopping object is folded back and the relative velocity overlaps in the vicinity of 0, the first chirp repetition period is changed from T1a to T1b in step ST4.

  Further, in the case of NO in step ST2, there is no particular problem, so the first chirp repetition period is set to T1a which is a normal value.

  Next, in step ST5, it is determined whether or not the difference between the relative velocity-Vs of the stationary object and the relative velocity V2 which is the first return in the second distance / temporal velocity calculation unit 116b is smaller than a predetermined value ΔV2. . In the case of YES, since the peak due to the stopping object is folded back and the relative velocity overlaps in the vicinity of 0, the second chirp repetition period is changed from T2a to T2b in step ST7.

  Further, in the case of NO at step ST5, there is no particular problem, so the second chirp repetition period is set to T2a which is a normal value.

  As described above, according to the present invention, by changing the repetition period of the chirp according to the vehicle speed, it is possible to prevent the peak due to the stop and the peak due to the preceding vehicle from overlapping, so that the preceding vehicle can be detected accurately. Is possible. That is, the control computing unit 11 determines whether or not the frequency of the relative velocity at which aliasing occurs by the object and the frequency of the object at the relative velocity at which aliasing does not overlap overlap, and if both frequencies overlap, aliasing occurs. The transmission cycle of the transmitter 12 is changed so that the frequency at which the object with the relative velocity is folded does not overlap the frequency of the object at which no aliasing occurs.

  Also, in the first embodiment, the relative speed is assumed to be approximately 0 on the assumption that the vehicle is following the preceding vehicle, but the relative speed of the preceding vehicle is estimated from the relative speed of the preceding vehicle detected in the past. The repetition cycle may be changed so that the peak and the peak due to the stop do not overlap.

  In addition, in the first embodiment, the repetition cycle is changed so that the peak of the preceding vehicle and the peak of the stop do not overlap, but the peripheral objects having a peak where folding does not occur and the peaks where folding occurs are If there is an object in the vicinity of the object, the repetition period may be changed so that the peaks of the two objects in the vicinity do not overlap.

  The present invention is not limited to the above-described embodiment, and the embodiment can be appropriately modified within the scope of the invention.

DESCRIPTION OF SYMBOLS 1 radar apparatus, 11 control arithmetic unit, 12 transmitter, 13 receiver, 14 analog digital converter, 15 memory, 121 voltage generation circuit, 125 transmission antenna, 131 reception antenna, 111 control part, 117 distance speed Calculation unit, 500 own vehicle, 501 preceding vehicle, 502 stop objects

In the radar apparatus according to the present invention, the distance between the transmitter and the receiver, the receiver for receiving the reflected wave from the surrounding objects, and the reception data of the receiver are frequency analyzed to determine the distance and relative velocity to the surrounding objects. For an object having a relative velocity that is calculated and that is a frequency outside the analysis range of frequency analysis corresponding to the relative velocity, the control computing device is provided with a control computing device that computes the relative velocity from the folded frequency. The relative velocity of the stop object is estimated from the own vehicle speed of the own vehicle, it is determined whether the frequency corresponding to the relative velocity of the stop object is folded back, and in the case of folding back, the folded frequency is estimated, and the own vehicle follows The transmission period of the transmitter is changed so that the frequency that is folded does not overlap with the frequency corresponding to the relative velocity of the preceding vehicle .

Claims (4)

  A transmitter that transmits an electromagnetic wave, a receiver that receives a reflected wave from a nearby object, and frequency analysis of received data from the receiver to calculate distance and relative velocity, and an analysis range of frequency analysis corresponding to relative velocity For an object having a relative velocity that is an outer frequency, the control computing unit calculates a relative velocity from the folded frequency, and the control computing unit determines a first frequency by the object of the relative velocity at which the folding occurs. It is determined whether or not the second frequency of an object at a relative velocity at which aliasing does not occur overlaps, and if the first frequency and the second frequency overlap, an object at a relative velocity at which aliasing occurs is folded A radar apparatus characterized in that a transmission cycle of the transmitter is changed so that the frequency does not overlap with the frequency of an object where aliasing does not occur.   The control arithmetic unit estimates the relative velocity of the stationary object from the own vehicle speed of the host vehicle, determines whether the frequency corresponding to the relative velocity of the stationary object is folded back, and estimates the folded frequency if folded back. The radar apparatus according to claim 1, wherein the transmission period of the transmitter is changed so that the folded frequency does not overlap with the frequency corresponding to the relative velocity of the preceding vehicle followed by the own vehicle.   The control computing unit estimates the distance and relative velocity of the current peripheral object from the distance and relative velocity of the peripheral object detected in the past, and turns back at the frequency corresponding to the estimated distance and relative velocity. The radar apparatus according to claim 1 or 2, wherein a transmission period of the transmitter is changed so that the frequencies do not overlap.   The control computing unit estimates the distance and relative velocity of the current peripheral object from the distance and relative velocity of the peripheral object detected in the past, and when the relative velocity of the peripheral object is folded back, it is set to the folded frequency The radar apparatus according to claim 1, wherein the transmission period of the transmitter is changed such that the frequencies of other surrounding objects whose relative velocities do not turn back do not overlap.

Images