JP7584859B2 - Apparatus and method for detecting moving speed - Google Patents

Description

This invention relates to a device and method for detecting moving speed, and in particular to a technology for estimating the moving speed of the radar device itself based on radar data obtained by processing the reflected waves that are returned after radio waves transmitted from a radar are reflected off the surface of an object.

A radar device that detects a target and estimates the relative speed of the target is known, which includes a radar antenna configured to repeatedly transmit and receive signals while rotating in a horizontal plane, a display that displays a radar image showing the position of targets around the device, and a speed estimation unit that estimates the relative speed between the device and the target in the radiation direction component of the radio waves from the device (see Patent Document 1).

JP 2010-266292 A

However, if it were possible to estimate the moving speed of the radar device itself based on the radar data acquired using a radio wave sensor/radar device, it would be useful to know the moving speed of various equipment, devices, vehicles, facilities, etc. by installing the radio wave sensor/radar device.

The present invention aims to provide a moving speed detection device and method that can estimate the moving speed of the radar device itself based on radar data.

In order to solve the above problem, the present invention includes a radar unit of a vehicle that emits a transmission wave and receives a reflected wave of the transmission wave that is reflected by a surrounding stationary object and outputs radar data; a signal processing unit that performs frequency analysis of the radar data to generate a frequency spectrum and calculates a distance and a relative speed to the surrounding stationary object ; a reception strength integrating unit that integrates the reception strength in the frequency spectrum for each value of the relative speed to calculate an integrated reception strength value for each value of the relative speed; a moving speed specifying unit that specifies the value of the relative speed (referred to as a "relative speed value") corresponding to the maximum value of the integrated reception strength; and a moving speed specifying unit that specifies the maximum value of the reception strength for each value of the relative speed and then specifies the value of the distance corresponding to the maximum value of the reception strength to generate combined data of the relative speed value and the distance value, and further includes a characteristic of the combined data in which the value of the relative speed is within a predetermined range among the combined data in which the value of the distance is within a predetermined range smaller than the value of the relative speed, and a characteristic of the combined data in which the value of the relative speed is within a predetermined range smaller than the value of the relative speed. and a travel speed output unit which, based on the result of the determination, outputs the relative speed value as the travel speed of the vehicle directly or outputs the relative speed value after performing calculation processing that takes into account the wraparound of the speed information, wherein the radar unit is installed on the vehicle so that the front direction of the radar unit is at a depression angle, and the predetermined range of distance values is set to approximately half of the range on the radar unit side of the range on the ground from a position of the radar unit orthogonal projection onto the ground to an intersection of the front direction and the ground, and the predetermined range in which the relative speed value is smaller than the relative speed value and the predetermined range in which the relative speed value is larger than the relative speed value have the same size and are set to a range of approximately 1/10 of the maximum detectable speed of the radar unit .

The invention described in claim 2 is characterized in that, in the moving speed detection device described in claim 1, the characteristic of the combination data is the number of combination data whose relative speed value is smaller than the relative speed value and the number of combination data whose relative speed value is larger than the relative speed value among the combination data whose distance value is within the predetermined range.

The invention described in claim 3 is characterized in that, in the moving speed detection device described in claim 1, the characteristics of the combination data are the average value of the distances of the combination data whose relative speed values are in the predetermined range smaller than the relative speed value among the combination data whose distance values are in the predetermined range, and the average value of the distances of the combination data whose relative speed values are in the predetermined range larger than the relative speed value.
It is characterized by:

The invention described in claim 4 provides a method for calculating a distance and a relative speed between a vehicle and a stationary object in the vicinity by performing a frequency analysis of radar data output from a radar device of a vehicle which emits a transmission wave and receives a reflected wave of the transmission wave reflected by a stationary object in the vicinity to generate a frequency spectrum, a process for integrating the reception strength in the frequency spectrum for each value of the relative speed to calculate an integrated reception strength value for each value of the relative speed, a process for identifying the value of the relative speed (referred to as a "relative speed value") corresponding to the maximum value of the integrated reception strength, and a process for identifying the maximum value of the reception strength for each value of the relative speed, and then identifying the value of the distance corresponding to the maximum value of the reception strength to generate combined data of the value of the relative speed and the value of the distance. and a process of determining whether or not wraparound of speed information occurs in the frequency analysis by comparing a characteristic of the combination data in which the value of the relative speed is in a predetermined range smaller than the relative speed value with a characteristic of the combination data in which the value of the relative speed is in a predetermined range larger than the relative speed value, among the combination data in which the value of the distance is in a predetermined range, and a process of outputting the relative speed value as the moving speed of the vehicle as it is or after performing a calculation process taking the wraparound of the speed information into consideration, based on a result of the determination. The predetermined range of the distance value refers to a process of outputting the relative speed value as the moving speed of the vehicle as it is or after performing a calculation process taking the wraparound of the speed information into consideration,
a predetermined range in which the relative velocity value is smaller than the relative velocity value and a predetermined range in which the relative velocity value is larger than the relative velocity value are the same in size and are set to a range of approximately 1/10 of the maximum detectable speed of the radar device.

The invention described in claim 5 is characterized in that, in the method for detecting the moving speed described in claim 4, the characteristics of the combination data include counting the number of combination data in which the value of the relative speed is smaller than the relative speed value among the combination data in which the value of the distance is within the predetermined range, and counting the number of combination data in which the value of the relative speed is larger than the relative speed value.

The invention described in claim 6 is characterized in that, in the method for detecting the moving speed described in claim 4, the characteristics of the combination data include calculating an average value of the distances of the combination data in which the relative speed value is smaller than the relative speed value among the combination data in which the distance value is within the predetermined range, and calculating an average value of the distances of the combination data in which the relative speed value is larger than the relative speed value.

According to the inventions described in claims 1 and 4, the moving speed of the radar device itself can be estimated based on radar data, so that by installing a radar device, it is possible to know the moving speed of various equipment, devices, vehicles, facilities, etc. from only the data received from one receiving antenna. According to the inventions described in claims 1 and 4, in particular, it is determined whether or not there is any leakage of speed information in the frequency analysis of the radar data, so that even if an object is detected that is faster than the system design speed of the radar device, it is possible to detect the correct relative speed, and thus it is possible to improve the reliability of the technology for estimating moving speed.

According to the inventions described in claims 2 and 3 and claims 5 and 6, it is possible to appropriately determine whether or not loopback of speed information occurs in the frequency analysis of radar data, and it is possible to more reliably detect the correct relative speed even if an object is detected that is faster than the system design speed of the radar device.

1 is a functional block diagram showing a schematic configuration of a moving speed detection device according to a first embodiment of the present invention; 2 is a flowchart showing a processing procedure in the moving speed detection device of FIG. 1 and also a processing procedure of a moving speed detection method in accordance with the first embodiment of the present invention; 1 is a diagram showing an example of data when a moving speed detection device is moving at about +15 km/h, (A) is a diagram showing an example of VR data output from a signal processing unit, and (B) is a diagram showing the relationship between the relative speed and the integrated reception intensity value for the VR data of (A). FIG. 4 is a diagram for explaining the details of the speed detected by the radar unit. 1 is a diagram showing an example of data when a moving speed detection device is moving at about +15 km/h, (A) is a diagram showing an example of VR data output from a signal processing unit, and (B) is a diagram showing the relationship between the relative speed and the maximum intensity distance value for the VR data of (A). 5(B) is a diagram for explaining counting the number of data in the relationship between the relative speed and the maximum intensity distance value in FIG. 5(A) is a diagram showing an example of setting a data counting distance range for the maximum intensity distance data. (B) is a partially enlarged view of the data counting distance range in (A), showing an example of setting a left speed range and a right speed range for the maximum intensity distance data. FIG. 13 is a diagram for explaining the concept of setting a data count distance range. 1 is a diagram showing data (simulation data) in the case where wraparound of velocity information occurs in fast Fourier transform processing, (A) is a diagram showing an example of VR data, and (B) is an enlarged view of a portion including a data count distance range of the relationship between the relative velocity and the maximum intensity distance value for the VR data of (A). 1 is a diagram showing an example of data when a moving speed detection device is moving at approximately -15 km/h. (A) is a diagram showing an example of VR data output from a signal processing unit. (B) is a diagram showing the relationship between the relative speed and the integrated reception intensity value for the VR data of (A). 9(A) is a diagram for explaining counting the number of data in the relationship between the relative speed and the maximum intensity distance value for the VR data of FIG. 9(A), (A) is a diagram showing an example of setting a data counting distance range for the maximum intensity distance data for the VR data of FIG. 9(A), (B) is a partially enlarged view of the data counting distance range of (A), showing an example of setting a left speed range and a right speed range for the maximum intensity distance data. 10 is a functional block diagram showing a schematic configuration of a moving speed detection device according to a second embodiment of the present invention; FIG. 12 is a flowchart showing the processing procedure in the moving speed detection device of FIG. 11 and also the processing procedure of the moving speed detection method according to the second embodiment of the present invention. This is an enlarged view of a portion including the range that satisfies the conditions of the average value calculation distance range of maximum intensity distance data and the left speed range and right speed range, and explains the calculation of the average value of the distance in the relationship between the relative speed and the maximum intensity distance value.

The present invention will be described below based on the illustrated embodiment.

(Embodiment 1)
Fig. 1 is a functional block diagram showing a schematic configuration of a moving speed detection device 1 according to a first embodiment of the present invention. Fig. 2 is a flowchart showing a processing procedure in the moving speed detection device 1 and a processing procedure of a moving speed detection method according to the first embodiment of the present invention.

The moving speed detection device 1 is a mechanism for estimating the moving speed of the device itself based on radar data acquired by a radar, and mainly comprises a control unit 2, a radar unit 3, a signal processing unit 4, a reception intensity integrating unit 5, a moving speed identifying unit 6, a loop detection unit 7, and a moving speed output unit 8. For example, as merely one example, the moving speed detection device 1 is mounted on a vehicle such as a train or an automobile, and is used to estimate the moving speed/traveling speed of the vehicle by estimating the moving speed of the moving speed detection device 1 itself.

The control unit 2 is a mechanism for controlling each part of the moving speed detection device 1, and is configured as a mechanism including a central processing unit 21 (CPU: abbreviation for Central Processing Unit) that performs calculations related to the detection of moving speed, a ROM 22 (ROM: abbreviation for Read Only Memory) which is a readable storage device, and a RAM 23 (RAM: abbreviation for Random Access Memory) which is a readable/writable storage device.

The control unit 2 uses the RAM 23 as a working area as necessary by executing a program stored in the ROM 22 for controlling the operation of the moving speed detection device 1 via the central processing unit 21, and controls the start, content, and end of processing of each part of the moving speed detection device 1 in accordance with the program.

The moving speed detection device 1 according to the first embodiment includes a radar unit 3 that emits a transmission wave and receives a reflected wave that is reflected by an object and returns to output radar data, a signal processing unit 4 that performs frequency analysis of the radar data to generate a frequency spectrum and calculates the distance R and relative speed V to the object, a reception intensity integration unit 5 that integrates the reception intensity I in the frequency spectrum for each value of the relative speed V to calculate an integrated reception intensity value Is for each value of the relative speed V, a moving speed determination unit 6 that specifies the value Vm of the relative speed V (referred to as the "relative speed value") corresponding to the maximum value Ismax of the reception intensity integrated value Is, and a moving speed determination unit 7 that specifies the maximum value Imax of the reception intensity I for each value of the relative speed V and then specifies the value Rm of the distance R corresponding to the maximum value Imax of the reception intensity I. The device has a loop detection unit 7 that generates combination data (V, Rm) of the value of the relative velocity V and the value of the distance R Rm, and compares the characteristics of the combination data (V, Rm) in which the value of the relative velocity V is in a predetermined range smaller than the relative velocity value with the characteristics of the combination data (V, Rm) in which the value of the relative velocity V is in a predetermined range larger than the relative velocity value to determine whether looping of the speed information has occurred in the frequency analysis, and a movement speed output unit 8 that outputs the relative velocity value as the movement speed of the device itself based on the result of the determination, or outputs it after performing calculation processing that takes into account the looping of the speed information (see FIG. 1).

The moving speed detection device 1 according to the first embodiment further configures the characteristics of the combination data (V, Rm) to be the number of combination data (V, Rm) in which the value Rm of the distance R falls within a predetermined range, in which the value of the relative speed V falls within a predetermined range smaller than the relative speed value, and the number of combination data (V, Rm) in which the value of the relative speed V falls within a predetermined range larger than the relative speed value.

In addition, the method of detecting the moving speed according to the first embodiment includes a process of performing frequency analysis of radar data output from the radar unit 3, which emits a transmission wave and receives a reflected wave that is returned by the transmission wave reflected by an object, to generate a frequency spectrum and calculate the distance R and relative speed V to the object (steps S1 to S4), a process of integrating the reception intensity I in the frequency spectrum for each value of the relative speed V to calculate the reception intensity integrated value Is for each value of the relative speed V (step S5), a process of identifying the value Vm (i.e., the relative speed value) of the relative speed V corresponding to the maximum value Ismax of the reception intensity integrated value Is, and a process of identifying the maximum value Imax of the reception intensity I for each value of the relative speed V, and then identifying the value Rm of the distance R corresponding to the maximum value Imax of the reception intensity I to calculate the relative speed. The system includes a process (steps S7-S9) of generating combination data (V, Rm) of the value of the degree V and the value of the distance R Rm, comparing the characteristics of the combination data (V, Rm) in which the value of the relative velocity V is in a predetermined range smaller than the relative velocity value with the characteristics of the combination data (V, Rm) in which the value of the relative velocity V is in a predetermined range larger than the relative velocity value to determine whether or not wraparound of the velocity information has occurred in the frequency analysis, and a process (step S10) of outputting the relative velocity value as the moving speed of the device itself or outputting it after performing a calculation process that takes the wraparound of the velocity information into account based on the result of the determination (see FIG. 2).

The method of detecting the moving speed according to the first embodiment further counts, as a characteristic of the combination data (V, Rm), the number of combination data (V, Rm) in which the value Rm of the distance R falls within a predetermined range and the number of combination data (V, Rm) in which the value of the relative speed V falls within a predetermined range smaller than the relative speed value, and the number of combination data (V, Rm) in which the value of the relative speed V falls within a predetermined range larger than the relative speed value (step S8) (see FIG. 2).

The radar unit 3 has a transmitter 31 and a receiver 32 and has the function of transmitting and receiving radio waves, and outputs radar data acquired by performing radar scanning using an FMCW (Frequency Modulated-Continuous Wave) radar system. In addition, the radar unit 3 may be configured as a MIMO (Multiple Input Multiple Output) radar having multiple transmitting antennas and multiple receiving antennas.

In the FMCW method, a frequency-modulated continuous wave (specifically, radio waves; equivalent to the transmitted signal) is transmitted as the transmitted wave, and a reflected wave (specifically, radio waves; equivalent to the received signal) that is reflected off the surface of the object is received. The difference between the transmitted wave and the received wave (i.e., the reflected wave) (in other words, the frequency difference between the transmitted wave and the received wave) is analyzed to calculate the distance between the radar unit 3 and the object, and the relative speed between the radar unit 3 and the object is calculated by measuring and analyzing the phase of the frequency of the calculated distance for each continuous wave.

FMCW radar is a continuous oscillation radar that performs frequency modulation over time, and generates and transmits (in other words, emits or radiates) a burst wave containing multiple chirps. Each chirp contained in the burst wave is generated by sweeping the frequency over time, so that the frequency changes linearly over time (specifically, increases/decreases). The modulation width and modulation period of the chirp frequency (i.e., the chirp repetition period) may be adjusted as appropriate.

Here, multiple chirps are transmitted at a specific time interval, and a series of multiple chirps that form a single unit is called a "chirp frame." One chirp frame corresponds to one radar scan, and each chirp frame is processed independently.

The transmitter 31 of the radar unit 3 is configured as a mechanism including, for example, a voltage generator, a voltage controlled oscillator, and a transmitting antenna.

The voltage generator generates and outputs a control voltage that changes in a triangular (or sawtooth) waveform, with successive alternating sections of gradually increasing level and gradually decreasing level on the time axis.

The voltage-controlled oscillator generates and outputs a transmission signal that changes in a triangular (or sawtooth) waveform in which modulation sections in which the frequency gradually increases and modulation sections in which the frequency gradually decreases alternately on the time axis in response to the control voltage.

The transmitting antenna generates a transmission wave based on the transmission signal and radiates the transmission wave into the space around the vehicle on which the moving speed detection device 1 is mounted (referred to as the "surrounding space"; it is preferable that the space includes the space along the traveling direction of the vehicle). A part of the transmission signal is also transmitted to the receiving unit 32 as a local signal at a predetermined distribution ratio.

The transmitter 31 generates radio waves (also called "millimeter waves") having a frequency of, for example, 79 GHz, 76 GHz, or 60 GHz, and radiates them into the surrounding space via a transmitting antenna. In this invention, it is preferable to use radio waves in a high frequency band.

The receiver 32 of the radar unit 3 is configured as a mechanism including, for example, a receiving antenna, a mixer, and an A/D converter.

The receiving antenna receives radio waves emitted from the transmitting antenna of the transmitter 31 (i.e., transmitted waves), including radio waves that are reflected off the surfaces of objects in the surrounding space and return (i.e., reflected waves; also called "Doppler reflected waves"), as received waves, and converts the received received waves/reflected waves into a received signal and outputs it.

The mixer mixes the radio waves (transmission signal; i.e., local signal) distributed and transmitted from the transmitter 31 with the radio waves (reception signal) output from the receiving antenna to generate and output a differential signal (note that this is an analog signal).

The A/D converter performs sampling processing (in other words, analog-to-digital conversion processing) on the differential signal output from the mixer using a predetermined sampling frequency, converts the differential signal into digital data, and outputs the digitized differential signal.

The differential signal output as radar data from the radar unit 3 after a radar scan is a signal having a frequency component that is the difference between the frequency component of the radio wave (transmission signal; i.e., local signal) distributed and transmitted from the transmission unit 31 and the frequency component of the radio wave (reception signal) output from the receiving antenna (i.e., a signal having a beat frequency, also called a "beat signal").

Each time a radar scan is performed, radar data is output from the radar unit 3 and input to the signal processing unit 4 (step S1).

The signal processing unit 4 performs frequency analysis of the radar data output from the radar unit 3, and uses the frequency analysis results to calculate distance information and motion information regarding the object that reflected the transmitted wave. The signal processing unit 4 includes a frequency analysis unit 41, a distance calculation unit 42, and a speed calculation unit 43.

The frequency analysis unit 41 performs frequency analysis of the differential signal (beat signal) as radar data (in other words, beat waveform data) output from the radar unit 3 (specifically, the A/D converter of the receiving unit 32) (step S2).

The frequency analysis unit 41 specifically performs a fast Fourier transform (FFT: short for Fast Fourier Transform) process on the beat waveform data for the sampling time width (e.g., 100 milliseconds) per radar scan, specifically the amplitude of the differential signal (beat signal), to generate and output a frequency spectrum (beat frequency spectrum) that indicates the frequency distribution of the amplitude of the differential signal. The frequency spectrum indicates the amplitude of each frequency component contained in the differential signal.

The magnitude of the amplitude and the frequency bin (in other words, the FFT bin) in the frequency spectrum correspond to the received intensity and beat frequency of the reflected wave from the object. From the received intensity and beat frequency in the frequency spectrum, the relative distance and relative speed of the object that reflected the transmitted wave can be obtained as distance information and motion information about the object.

The distance calculation unit 42 calculates and outputs the distance R between the radar unit 3 and the object based on the frequency spectrum output from the frequency analysis unit 41 (step S3). The distance R is calculated for each frequency bin in the frequency spectrum that is the result of the frequency analysis in the processing of step S2.

There are known methods for calculating distance based on the frequency spectrum, and this invention is not limited to a specific method, so a detailed explanation will be omitted here. For example, the distance between the radar unit 3 and an object that reflects the transmitted wave can be calculated by a known method such as a method that utilizes the fact that the difference between the frequency of the transmitted wave and the frequency of the received wave increases or decreases in proportion to the distance between the radar unit 3 and the object.

The velocity calculation unit 43 calculates and outputs the relative velocity V between the radar unit 3 and the object (specifically, the instantaneous relative velocity when the transmitted wave is reflected by the surface of the object) based on the frequency spectrum output from the frequency analysis unit 41 (step S4). The relative velocity V is calculated for each frequency bin in the frequency spectrum that is the result of the frequency analysis in the processing of step S2.

There are known methods for calculating the relative velocity based on the frequency spectrum, and this invention is not limited to a specific method, so detailed explanation will be omitted here. For example, the relative velocity between the radar unit 3 and an object can be calculated by a known method such as a method that utilizes the fact that when the radar unit 3 and an object that reflects the transmitted waves are moving relative to each other, the frequency of the radio waves (i.e., the received waves) reflected by the surface of the object and received by the receiving antenna is affected by the relative velocity of the radio waves with respect to the frequency of the radio waves (i.e., the transmitted waves) transmitted from the transmitting antenna when reflected by the surface of the object, and the Doppler effect causes a shift in accordance with the relative velocity between the radar unit 3 and the object.

The signal processing unit 4 outputs data (V, R, I) consisting of a combination of the relative speed V (unit: km/h) between the radar unit 3 and the object, the distance R (unit: m) between the radar unit 3 and the object, and the reception intensity I, which is the absolute value of the amplitude for each frequency bin, calculated for each frequency bin in the frequency spectrum as a result of the frequency analysis based on the radar data output from the radar unit 3 through the above processing. The data (V, R, I) output from the signal processing unit 4 is called "VR data".

Note that distance R and relative velocity V are calculated for each frequency bin in the frequency spectrum, and if there are multiple combinations of distance R and relative velocity V with the same value, the sum of the reception intensity I values for each combination of distance R and relative velocity V is used as the reception intensity I value for that combination of distance R and relative velocity V.

The processing by the signal processing unit 4 is performed for each radar scan of a predetermined time period (in other words, the sampling time width). That is, each time a radar scan is performed, a set of VR data (V, R, I) related to that radar scan is generated and output.

An example of VR data (V, R, I) is shown in Fig. 3(A). In Fig. 3(A), the horizontal axis represents relative speed V and the vertical axis represents distance R, and the value of reception intensity I corresponding to the combination of (V, R) is displayed in a different color according to the magnitude of the value. In Fig. 3(A), a small value of reception intensity I is displayed darker, and as the value of reception intensity I increases, it becomes brighter.

When the moving speed detection device 1 (specifically, the transmitting antenna and receiving antenna) moves, a spectrum appears with a speed component corresponding to (in other words, equivalent to) the moving speed of the moving speed detection device 1 itself, as shown in FIG. 3(A), in relation to the waves reflected from surrounding stationary objects (for example, the ground/road surface, structures, or equipment fixedly installed on the ground/land). In this invention, the moving speed of the moving speed detection device 1 itself is estimated by focusing on the waves reflected from surrounding stationary objects. In other words, in this invention, the moving speed of the moving speed detection device 1 itself is estimated by calculating the relative speed of the device itself with respect to the surrounding stationary objects.

Specifically, the relative speed at the position where the value of reception intensity I is large over the entire distance, as indicated by the upward arrow in Figure 3 (A), is the speed component that corresponds (in other words, is equivalent) to the actual movement speed of the movement speed detection device 1 itself when the VR data was acquired (which is approximately +15 km/h). Note that when the movement speed of the movement speed detection device 1 itself is 0 (i.e., the movement speed detection device 1 is stopped), the value of reception intensity I becomes large at the position where the relative speed value is 0.

In relation to Figure 3 (A), when radio waves (i.e., transmission waves) transmitted from the transmitting antenna of the radar unit 3 strike the ground, various relative velocities are detected depending on the direction relative to the radar unit 3 (see Figure 4). Specifically, the relative velocity corresponding to the radio waves reflected back from the front of the radar unit 3 (specifically, the transmitting antenna and receiving antenna) is the maximum, and is the relative velocity closest to the true value. On the other hand, the further away from the front of the radar unit 3 is, the smaller the apparent relative velocity detected by the radar unit 3 becomes. And since the antenna gain is greatest directly in front of the radar unit 3, the maximum relative velocity is seen the furthest (in other words, the value of the receiving intensity I is large over the entire distance R).

The reception intensity integrator 5 calculates the reception intensity integrated value for each relative velocity value for the set of VR data (V, R, I) output from the signal processor 4 (step S5).

The reception intensity integrator 5 uses a set of VR data (V, R, I) to integrate the value of reception intensity I for each value of relative velocity V to calculate an integrated reception intensity value Is for each value of relative velocity V. The integrated reception intensity value Is is the integrated value of reception intensity I in the direction of distance R for each value of relative velocity V in a VR plane as shown in FIG. 3A, which is configured by a set of VR data (V, R, I). Note that the reception intensity integrator 5 may, as necessary, divide the value of relative velocity V into a predetermined range and integrate the value of reception intensity I for each speed rank (in other words, speed bin). In the description of the embodiment, the term "value of relative velocity V" is used to include the meaning of "speed bin".

The reception intensity integrator 5 outputs a set of data (V, Is) consisting of a combination of the relative velocity V and the reception intensity integrated value Is. The data (V, Is) output from the reception intensity integrator 5 is called "reception intensity integrated value data."

Figure 3(B) shows a set of integrated reception intensity data (V, Is) calculated using the set of VR data (V, R, I) shown in Figure 3(A). In Figure 3(B), the horizontal axis represents relative speed V and the vertical axis represents integrated reception intensity Is. In Figure 3(B), it can be seen that the value of integrated reception intensity Is is maximum at the position of the speed component that corresponds (in other words, is equivalent) to the actual moving speed of the moving speed detection device 1 itself when the data in question was acquired (i.e., approximately +15 km/h).

When calculating the reception intensity integrated value Is, the reception intensity I may be integrated for each value of the relative velocity V over the entire range of the distance R calculated in the processing of step S3, or the reception intensity I may be integrated for each value of the relative velocity V over a specific range of the calculated distance R.

When calculating the reception intensity integrated value Is, for example, if a part of the vehicle structure is located near the radar unit 3 (particularly the transmitting antenna, the receiving antenna) and reflects the transmission wave emitted from the transmitting antenna, the distance between the radar unit 3 and the part of the structure may be taken into consideration, and the value of the reception intensity I may be integrated for each value of the relative speed V, excluding the VR data (V, R, I) for a combination where the distance R is near the radar unit 3 and the relative speed V is close to 0.

The moving speed determination unit 6 uses the set of reception intensity integrated value data (V, Is) output from the reception intensity integrator 5 to determine the relative speed value at which the reception intensity integrated value is maximum (step S6).

The moving speed determination unit 6 identifies the maximum value Ismax of the integrated reception strength value Is from the set of integrated reception strength value data (V, Is), and identifies and outputs the value Vm of the relative speed V (i.e., the relative speed value) combined with the identified maximum value Ismax of the integrated reception strength value Is.

Here, in FMCW radar, the maximum detectable speed is determined by the system design (specifically, the chirp interval). For this reason, it is not possible to detect speeds above the designed speed. Furthermore, when the relative speed is calculated using FMCW radar, a fast Fourier transform process is performed. In the fast Fourier transform process, if an object traveling at a speed above the designed speed is detected, the speed information wraps around (also called "foldback"), making it impossible to detect the correct relative speed.

The moving speed detection device 1 therefore has a loopback detection unit 7 as a mechanism for determining whether the detected relative speed is correct by focusing on information other than the value of the relative speed itself.

The loopback detection unit 7 determines whether loopback of speed information occurs in the fast Fourier transform process based on the characteristics of the data related to the value Vm of the relative speed V output from the moving speed determination unit 6. The loopback detection unit 7 includes a maximum strength determination unit 71, a data number counting unit 72, and a loopback determination unit 73.

The maximum strength identification unit 71 identifies the distance value at which the reception strength is maximum for each relative velocity value for the set of VR data (V, R, I) output from the signal processing unit 4 (step S7).

The maximum strength identification unit 71 uses a set of VR data (V, R, I) to identify the maximum value Imax of the reception strength I for each value of the relative speed V, and identifies the value Rm of the distance R that is combined with the identified maximum value Imax of the reception strength I. The value Rm of the distance R identified by the maximum strength identification unit 71 is called the "maximum strength distance value."

The maximum strength identification unit 71 outputs a set of data (V, Rm) consisting of a combination of the relative velocity V and the maximum strength distance value Rm. The data (V, Rm) output from the maximum strength identification unit 71 is called "maximum strength distance data."

Figure 5(B) shows a set of maximum intensity distance data (V, Rm) calculated using the set of VR data (V, R, I) shown in Figure 5(A). In Figure 5(B), the horizontal axis represents relative velocity V and the vertical axis represents maximum intensity distance value Rm. The circles in Figure 5(B) are plots corresponding to each combination of maximum intensity distance data (V, Rm). Note that the VR data (V, R, I) shown in Figure 5(A) is the same data as the VR data (V, R, I) shown in Figure 3(A).

The data number counting unit 72 counts the number of pieces of data that satisfy a predetermined condition for the set of maximum strength distance data (V, Rm) output from the maximum strength identification unit 71 (step S8).

The data number counting unit 72 uses the set of maximum intensity distance data (V, Rm) to count the number of data whose maximum intensity distance value Rm falls within a specified range and whose relative velocity V value falls within a specified range.

Specifically, first, a lower limit and an upper limit are set for the range of the maximum intensity distance value Rm when counting the number of data items. The lower limit may be set to 0 m. The range of the maximum intensity distance value Rm when counting the number of data items is called the "data counting distance range."

The data counting distance range is not limited to a specific range, but is set appropriately, for example, taking into consideration the specifications/performance (specifically, for example, the irradiation range) of the radar equipment used as the radar unit 3.

As shown in FIG. 7, for example, the data counting distance range is assumed to be set to about half of the range of the ground Gp-i from the orthogonal projection position Gp of the radar unit 3 (specifically, the transmission antenna, the reception antenna) onto the ground G to the intersection point Gi of the front direction Df of the radar unit 3 and the ground G, on the assumption that there is a reflection point and a reflection range of the radio wave (i.e., the transmission wave) emitted from the transmission antenna of the radar unit 3 on the ground Gp-i from the orthogonal projection position Gp of the radar unit 3 onto the ground G to the intersection point Gi of the front direction Df of the radar unit 3 and the ground G. Specifically, for example, when the distance on the ground Gp-i from the orthogonal projection position Gp of the radar unit 3 to the intersection point Gi of the front direction Df of the radar unit 3 and the ground G is 10 m, the lower limit of the data counting distance range can be set to 0 m and the upper limit can be set to 5 m. That is, the data counting distance range can be set to 0≦Rm≦5. As shown in the example in FIG. 7, it is preferable that the radar unit 3 is installed (i.e., attached to a vehicle, etc.) so that the front direction Df of the radar unit 3 is adjusted to a depression angle.

Figure 6(A) shows an example of setting the data counting distance range for the set of maximum intensity distance data (V, Rm) shown in Figure 5(B) (the range surrounded by the dashed line in the figure is the data counting distance range). The display method in Figure 6 is the same as that in Figure 5(B). In the example shown in Figure 6, the lower limit of the data counting distance range is set to 0m and the upper limit is set to 5m, and the data counting distance range is set to 0≦Rm≦5, just as an example.

The range of relative velocity V when counting the number of data items is set to a range smaller than the value Vm of relative velocity V (i.e., the relative velocity value) output from the movement velocity identification unit 6, and a range larger than the value Vm of relative velocity V (i.e., the relative velocity value) (see FIG. 6B). The range of relative velocity V set to a range smaller than the value Vm of relative velocity V when counting the number of data items is called the "left side velocity range", and the range of relative velocity V set to a range larger than the value Vm of relative velocity V is called the "right side velocity range".

The left speed range and the right speed range are not limited to a specific range, but are appropriately set to an appropriate range, taking into consideration, for example, the specifications/performance (specifically, for example, the maximum detectable speed) of the radar equipment used as the radar unit 3. The left speed range and the right speed range are set so that the size of each range/width is the same.

The left speed range and the right speed range may each be set to, for example, a range of about 1/10 of the maximum detectable speed of the radar unit 3. Specifically, for example, when the maximum detectable speed of the radar unit 3 is ±100 km/h and the value Vm of the relative speed V output from the moving speed determination unit 6 is +15 km/h, the left speed range may be set to a range of +5 to +15 km/h and the right speed range may be set to a range of +15 to +25 km/h. In other words, the left speed range may be set to +5≦V<+15 and the right speed range may be set to +15<V≦+25.

When the moving speed of the moving speed detection device 1 itself (i.e., the value Vm of the relative speed V) is near the boundary of the maximum detectable speed of the radar unit 3, depending on the width set as the left speed range or the right speed range, the left speed range or the right speed range is set as a range that is folded back to accommodate the wraparound of the speed information.

The data number counting unit 72 counts the number of pieces of data for which the maximum strength distance value Rm is within the data counting distance range and the value of the relative velocity V is within the left speed range for a set of maximum strength distance data (V, Rm). The number of pieces of data within the data counting distance range and the left speed range is called the "left data number."

The data number counting unit 72 counts the number of pieces of data for a set of maximum intensity distance data (V, Rm) in which the maximum intensity distance value Rm is within the data counting distance range and the value of the relative velocity V is within the right speed range. The number of pieces of data within the data counting distance range and the right speed range is called the "right data number."

The loopback determination unit 73 determines whether loopback of speed information has occurred in the fast Fourier transform process based on the number of left-side data and the number of right-side data output from the data number counting unit 72 (step S9).

The loopback determination unit 73 compares the number of left-side data with the number of right-side data, and determines whether loopback of speed information has occurred in the fast Fourier transform processing by the frequency analysis unit 41 based on the magnitude relationship between the two.

Specifically, by comparing the number of left side data with the number of right side data, if the number of data in the range closer to the position where the value of relative speed V is 0, based on the position of the value Vm of relative speed V, is greater (in the example shown in FIG. 6B, the number of left side data in the left speed range), the wraparound determination unit 73 determines that wraparound of speed information has not occurred.

On the other hand, when comparing the number of left-side data with the number of right-side data, if the number of data in the range farther from the position where the value of relative velocity V is 0, based on the position of the value Vm of relative velocity V, is greater (in the example shown in FIG. 6B, the number of right-side data within the right-side velocity range), the loopback determination unit 73 determines that loopback of speed information has occurred.

For example, in the example shown in FIG. 6(B), the number of left-side data is 80 and the number of right-side data is 35. The number of left-side data, which is the number of pieces of data in the range (i.e., the left-side speed range) closer to the position where the value of relative speed V is 0, based on the position of the value Vm of relative speed V (i.e., approximately +15 km/h), is greater, so the wraparound determination unit 73 determines that wraparound of speed information has not occurred.

Figure 8 shows an example in which the number of data points is greater in the range farther away from the position where the value of relative velocity V is 0, with the position of the value Vm of relative velocity V as the reference point. The example shown in Figure 8 is simulation data.

Figure 8(A) is an example of a set of VR data (V, R, I). The display method of Figure 8(A) is the same as that of Figure 3(A).

A set of VR data (V, R, I) shown in FIG. 8(A) is used to calculate a set of integrated reception intensity data (V, Is), the maximum value Ismax of the integrated reception intensity value Is is identified from the set of integrated reception intensity data (V, Is), and the value Vm of the relative speed V combined with the identified maximum value Ismax of the integrated reception intensity value Is is identified to be +70 km/h.

In addition, a set of maximum intensity distance data (V, Rm) is generated using the set of VR data (V, R, I) shown in Figure 8 (A), and a data counting distance range is set for the set of maximum intensity distance data (V, Rm), and a left speed range and a right speed range are set to count the number of data for each. The number of left data items is counted to be 8 and the number of right data items is counted to be 51.

In the example shown in FIG. 8, the distance on the ground Gp-i from the orthogonal projection position Gp of the radar unit 3 to the intersection point Gi of the front direction Df of the radar unit 3 and the ground G is 10 m, and the lower limit of the data count distance range is set to 0 m and the upper limit is set to 5 m. In other words, the data count distance range is set to 0≦Rm≦5.

In the example shown in FIG. 8, the maximum detectable speed of the radar unit 3 is ±113.6 km/h, the value Vm of the relative speed V is +70 km/h, the left speed range is set to the range of +58.64 to +70 km/h, and the right speed range is set to the range of +70 to +81.36 km/h. In other words, the left speed range can be set to +58.64≦V<+70, and the right speed range can be set to +70<V≦+81.36.

In the example shown in FIG. 8B, when comparing the number of left-side data and the number of right-side data, the number of left-side data is 8 and the number of right-side data is 51. The number of right-side data, which is the number of pieces of data in the range farther from the position where the value of relative speed V is 0 (i.e., the right-side speed range) based on the position of the value Vm (i.e., +70 km/h) of relative speed V, is greater, so the loopback determination unit 73 determines that loopback of speed information has occurred.

Furthermore, Figures 3, 5, and 6 are examples of data when the moving speed detection device 1 itself is moving at approximately +15 km/h, while Figures 9 and 10 show examples of data when the moving speed detection device 1 itself is moving at approximately -15 km/h.

Figure 9 (A) is an example of a collection of VR data (V, R, I) output from the signal processing unit 4 when the moving speed detection device 1 itself is moving at approximately -15 km/h. The display method of Figure 9 (A) is the same as that of Figure 3 (A).

Figure 9(B) shows a set of integrated reception intensity data (V, Is) calculated by the reception intensity integrator 5 using the set of VR data (V, R, I) shown in Figure 9(A). The display method of Figure 9(B) is the same as that of Figure 3(B). In Figure 9(B), it can be seen that the value of the integrated reception intensity value Is is maximum at the position of the speed component that corresponds (in other words, is equivalent to) the actual moving speed of the moving speed detection device 1 itself when the data in question was acquired (i.e., approximately -15 km/h).

Figure 10 (A) is a diagram showing an example of setting the data counting distance range for a set of maximum intensity distance data (V, Rm) calculated using the set of VR data (V, R, I) shown in Figure 9 (A) (the range surrounded by a dashed line in the figure is the data counting distance range). The display method of Figure 10 (A) is the same as that of Figure 5 (B). In the example shown in Figure 10, the lower limit of the data counting distance range is set to 0 m and the upper limit is set to 5 m, and the data counting distance range is set to 0 ≦ Rm ≦ 5, just as an example.

Figure 10 (B) is a partially enlarged view of the data counting distance range in Figure 10 (A), showing an example of setting the left and right speed ranges for a set of maximum intensity distance data (V, Rm).

In the example shown in Figures 9 and 10, the number of left-side data is 18 and the number of right-side data is 78. The number of right-side data, which is the number of pieces of data in the range closer to the position where the value of relative speed V is 0 (i.e., the right-side speed range) based on the position of the value Vm of relative speed V (i.e., approximately -15 km/h), is greater, so the wraparound determination unit 73 determines that wraparound of speed information has not occurred.

On the other hand, if the number of data points in the range farther from the position where the value of relative velocity V is 0, based on the position of the value Vm of relative velocity V (in the example shown in FIG. 10(B) , the number of left-side data points in the left-side velocity range) is greater, the wraparound determination unit 73 determines that wraparound of speed information has occurred.

If the loopback determination unit 73 determines that loopback of the speed information has not occurred, it outputs a message indicating that loopback has not occurred, and if it determines that loopback of the speed information has occurred, it outputs a message indicating that loopback has occurred as a result of the determination of whether loopback has occurred.

The moving speed output unit 8 outputs the moving speed of the moving speed detection device 1 based on the value Vm of the relative speed V output from the moving speed determination unit 6 and the determination result of the occurrence or non-occurrence of a wraparound output from the wraparound detection unit 7 (step S10).

When the wraparound detection unit 7 outputs a determination result indicating that no wraparound of speed information has occurred, the movement speed output unit 8 outputs the value Vm of the relative speed V output from the movement speed identification unit 6 as the movement speed of the movement speed detection device 1.

On the other hand, when the wraparound detection unit 7 outputs a determination result indicating that wraparound of speed information has occurred, the movement speed output unit 8 performs a calculation process on the value Vm of the relative speed V output from the movement speed determination unit 6, taking into account wraparound of the speed information, and outputs it as the movement speed of the movement speed detection device 1.

When leakage of speed information occurs, specifically, assuming that the maximum detectable speed of the radar unit 3 is ±Vr (km/h), the moving speed output unit 8 outputs the speed Vm' (km/h) calculated by the following formula 1A or 1B as the moving speed of the moving speed detection device 1. Note that when leakage of speed information occurs and the value Vm of the relative speed V is greater than 0 (i.e., when Vm>0), the speed Vm' is calculated as a negative value in terms of calculation.
(Equation 1A) Vm' = -Vr - (Vr - Vm) (when Vm > 0)
(Equation 1B) Vm' = + Vr + (Vr - Vm) (when Vm < 0)

In the example shown in Figure 8, specifically, the maximum detectable speed ±Vr of the radar unit 3 is ±113.6 km/h, and the value Vm of the relative speed V is +70 km/h (i.e., Vm > 0), and leakage of speed information is occurring. Therefore, the absolute value of the speed Vm' (km/h) calculated by the following formula 2, in which numerical values are substituted into the above formula 1A, is output as the moving speed of the moving speed detection device 1.
(Equation 2) Vm' = -113.6 - (113.6 - 70) = -157.2

When the value Vm of the relative speed V output from the moving speed determination unit 6 is 0, the moving speed output unit 8 outputs 0 as the moving speed of the moving speed detection device 1.

(Embodiment 2)
Fig. 11 is a functional block diagram showing a schematic configuration of a moving speed detection device 1 according to embodiment 2 of the present invention. Fig. 12 is a flowchart showing a processing procedure in the moving speed detection device 1 and a processing procedure of a moving speed detection method according to embodiment 2 of the present invention.

In this embodiment, the method of determining whether or not loopback of speed information has occurred in the fast Fourier transform process differs from that of embodiment 1. Specifically, the loopback detection unit 7 includes an average distance calculation unit 74 instead of a data number counting unit 72, and the process content of steps S8 and S9 is different. However, other configurations and process content are the same as those of embodiment 1. Therefore, the same reference numerals are used to denote configurations and process content equivalent to those of embodiment 1, and their description will be omitted.

In this embodiment, the processes from step S1 to step S7 performed by the radar unit 3, the signal processing unit 4, the reception intensity integrator 5, the moving speed determination unit 6, and the maximum intensity determination unit 71 of the loopback detection unit 7 are the same as those in the first embodiment.

In this embodiment, the loop detection unit 7 includes a maximum strength determination unit 71, an average distance calculation unit 74, and a loop determination unit 73.

The moving speed detection device 1 according to the second embodiment is configured so that the characteristics of the maximum intensity distance data (V, Rm) are the average value of the maximum intensity distance values Rm of the maximum intensity distance data (V, Rm) in which the value Rm of the distance R falls within a predetermined range and the value of the relative speed V falls within a predetermined range smaller than the relative speed value, and the average value of the maximum intensity distance values Rm of the maximum intensity distance data (V, Rm) in which the value Rm of the distance R falls within a predetermined range larger than the relative speed value.

The method of detecting the moving speed according to the second embodiment calculates the average value of the maximum intensity distance values Rm of the maximum intensity distance data (V, Rm) in which the value Rm of the distance R falls within a predetermined range and the value of the relative velocity V falls within a predetermined range smaller than the relative velocity value, as well as the average value of the maximum intensity distance values Rm of the maximum intensity distance data (V, Rm) in which the value Rm of the distance R falls within a predetermined range larger than the relative velocity value (step S8).

The average distance calculation unit 74 calculates the average value of the maximum strength distance value Rm for the set of maximum strength distance data (V, Rm) output from the maximum strength identification unit 71 (step S8).

The average distance calculation unit 74 uses a set of maximum intensity distance data (V, Rm) to calculate the average value of the maximum intensity distance values Rm for data in which the maximum intensity distance value Rm is within the average calculation distance range and the value of the relative velocity V is within the left speed range. The average value of the maximum intensity distance values Rm calculated for a data group within the average calculation distance range and the left speed range is called the "left distance average value."

The average distance calculation unit 74 uses the set of maximum intensity distance data (V, Rm) and calculates the average value of the maximum intensity distance value Rm for data in which the maximum intensity distance value Rm is within the average calculation distance range and the value of the relative velocity V is within the right speed range. The average value of the maximum intensity distance value Rm calculated for the data group within the average calculation distance range and the right speed range is called the "right distance average value."

The concept of setting the average calculation distance range is the same as the concept of setting the data count distance range in embodiment 1. The left speed range and right speed range are also the same as in embodiment 1.

An example of the calculation of the left distance average value and the right distance average value is shown in Figure 13. The display method in Figure 13 is the same as in Figure 5(B), and Figure 13 shows an enlarged view of the portion including the range that satisfies the conditions of the average calculation distance range and the left speed range and the right speed range.

The specifications/performance of the radar unit 3 used when the data shown in FIG. 13 was acquired are that the distance on the ground Gp-i from the orthogonal projection position Gp of the radar unit 3 to the intersection Gi of the front direction Df of the radar unit 3 and the ground G is 10 m, and the maximum detectable speed is ±113.6 km/h. In addition, the value Vm of the relative speed V identified by the moving speed identification unit 6 is -15.7631 km/h.

In the example shown in Figure 13, the lower limit of the average calculation distance range is set to 0 m and the upper limit is set to 5 m. In the example shown in Figure 13, the left speed range is set to -27.1231 to -15.7631 km/h and the right speed range is set to -15.7631 to -4.4031 km/h.

In the example shown in Figure 13, the average left distance value is calculated to be 4.0071 m, and the average right distance value is calculated to be 2.3989 m.

In this embodiment, the loopback determination unit 73 determines whether loopback of speed information has occurred in the fast Fourier transform process based on the left-side distance average value and the right-side distance average value output from the average distance calculation unit 74 (step S9).

The loopback determination unit 73 compares the left-side distance average value with the right-side distance average value, and determines whether loopback of speed information has occurred in the fast Fourier transform processing by the frequency analysis unit 41 based on the magnitude relationship between the left-side distance average value and the right-side distance average value.

Specifically, by comparing the left-side distance average value with the right-side distance average value, if the average value of the distance in the range closer to the position where the value of relative speed V is 0, based on the position of the value Vm of relative speed V, is smaller (in the example shown in FIG. 13, the right-side distance average value of the right-side speed range), the wraparound determination unit 73 determines that wraparound of speed information has not occurred.

On the other hand, when comparing the left-side distance average value with the right-side distance average value, if the average value of the distance in the range farther from the position where the value of relative velocity V is 0, based on the position of the value Vm of relative velocity V (in the example shown in FIG. 13, the left-side distance average value of the left-side velocity range) is smaller, the wraparound determination unit 73 determines that wraparound of speed information has occurred.

For example, in the example shown in FIG. 13, the left-side distance average value is 4.0071 m and the right-side distance average value is 2.3989 m. The right-side distance average value, which is the average value of the distance in the range (i.e., the right-side speed range) closer to the position where the value of relative speed V is 0, is smaller than the position where the value of relative speed V is Vm (i.e., -15.7631 km/h), so the wraparound determination unit 73 determines that wraparound of speed information has not occurred.

If the loopback determination unit 73 determines that loopback of the speed information has not occurred, it outputs a message indicating that loopback has not occurred, and if it determines that loopback of the speed information has occurred, it outputs a message indicating that loopback has occurred, as a result of the determination of whether loopback has occurred.

The moving speed output unit 8 outputs the moving speed of the moving speed detection device 1 based on the value Vm of the relative speed V output from the moving speed determination unit 6 and the determination result of the occurrence or non-occurrence of a wraparound output from the wraparound detection unit 7 (step S10).

The processing of step S10 by the movement speed output unit 8 is the same as in embodiment 1.

The above-described moving speed detection device 1 and moving speed detection method allow the moving speed of the radar device (radar unit 3) itself to be estimated based on radar data, so by installing a radar device, it becomes possible to know the moving speed of various equipment, devices, vehicles, facilities, etc., based on only the received data from one receiving antenna system.

The above-described moving speed detection device 1 and moving speed detection method are particularly adapted to determine whether or not loopback of speed information occurs in the frequency analysis of radar data, making it possible to detect a correct relative speed even if an object is detected that is faster than the system design speed of the radar device, thereby improving the reliability of the technology for estimating moving speed.

The above describes an embodiment of the present invention, but the specific configuration is not limited to the above embodiment, and any design changes that do not deviate from the gist of the present invention are also included in the present invention.

Specifically, in the above-mentioned embodiment 1, it is determined whether or not wraparound of speed information has occurred in the fast Fourier transform processing based on the number of left-side data and the number of right-side data counted using the set of maximum intensity distance data (V, Rm), and in the above-mentioned embodiment 2, it is determined based on the left-side distance average value and the right-side distance average value calculated using the set of maximum intensity distance data (V, Rm). However, the index for determining whether wraparound has occurred is not limited to the number of data or the average distance value. In other words, any index may be used as long as it shows the difference between the characteristics of the maximum intensity distance data included in the left-side speed range and the characteristics of the maximum intensity distance data included in the right-side speed range among the maximum intensity distance data within the data count distance range/average calculation distance range for the set of maximum intensity distance data (V, Rm).

1 Movement speed detection device 2 Control unit 21 Central processing unit 22 ROM
23 RAM
3 radar unit 31 transmission unit 32 reception unit 4 signal processing unit 41 frequency analysis unit 42 distance calculation unit 43 speed calculation unit 5 reception intensity integration unit 6 movement speed determination unit 7 loopback detection unit 71 maximum intensity determination unit 72 data number counting unit (first embodiment)
73 wraparound determination unit 74 average distance calculation unit (second embodiment)
8. Movement speed output section

Claims (6)

a radar unit of the vehicle that emits a transmission wave, receives a reflected wave that is reflected by a surrounding stationary object , and outputs radar data;
a signal processing unit that performs frequency analysis of the radar data to generate a frequency spectrum and calculates a distance and a relative velocity between the radar data and a stationary object in the vicinity ;
a reception strength integrating unit that integrates reception strength in the frequency spectrum for each value of the relative speed to calculate an integrated reception strength value for each value of the relative speed;
a moving speed determination unit that determines a value of the relative speed (referred to as a "relative speed value") that corresponds to a maximum value of the integrated reception strength value;
a loopback detection unit that identifies a maximum value of the reception strength for each value of the relative speed, and then identifies the distance value corresponding to the maximum value of the reception strength to generate combined data of the relative speed value and the distance value, and compares a characteristic of the combined data in which the relative speed value is in a predetermined range smaller than the relative speed value with a characteristic of the combined data in which the relative speed value is in a predetermined range larger than the relative speed value to determine whether loopback of speed information has occurred in the frequency analysis;
a travel speed output unit that outputs the relative speed value as the travel speed of the vehicle based on the result of the determination , or outputs the relative speed value after performing a calculation process that takes into account the wraparound of the speed information;
the predetermined range of distance values is set to approximately half of the range on the radar unit side of the ground from a position where the radar unit is orthogonally projected onto the ground to an intersection point between the front direction and the ground, when the radar unit is installed on the vehicle so that the front direction of the radar unit is at a depression angle;
the predetermined range in which the value of the relative velocity is smaller than the relative velocity value and the predetermined range in which the value of the relative velocity is larger than the relative velocity value have the same size and are set to a range of approximately 1/10 of the maximum detectable velocity of the radar unit.
A moving speed detection device characterized by: the characteristic of the combination data is the number of combination data whose distance value is within the predetermined range and whose relative velocity value is within the predetermined range smaller than the relative velocity value, and the number of combination data whose relative velocity value is within the predetermined range larger than the relative velocity value,
2. The moving speed detection device according to claim 1 . the characteristic of the combination data is an average value of the distances of the combination data in which the value of the distance falls within the predetermined range and the value of the relative velocity falls within the predetermined range smaller than the relative velocity value, and an average value of the distances of the combination data in which the value of the relative velocity falls within the predetermined range larger than the relative velocity value,
2. The moving speed detection device according to claim 1 . A process of performing frequency analysis of radar data output from a radar device of a vehicle that emits a transmission wave and receives a reflected wave that is reflected by surrounding stationary objects , generating a frequency spectrum, and calculating a distance and a relative speed to the surrounding stationary objects ;
A process of integrating the reception strength in the frequency spectrum for each value of the relative speed to calculate an integrated reception strength value for each value of the relative speed;
A process of identifying the value of the relative velocity corresponding to the maximum value of the integrated reception intensity value (referred to as a "relative velocity value");
a process of identifying a maximum value of the reception strength for each value of the relative velocity, identifying the value of the distance corresponding to the maximum value of the reception strength, generating combined data of the values of the relative velocity and the values of the distance, and comparing a characteristic of the combined data in which the value of the relative velocity is in a predetermined range smaller than the relative velocity value with a characteristic of the combined data in which the value of the relative velocity is in a predetermined range larger than the relative velocity value to determine whether or not leakage of velocity information has occurred in the frequency analysis;
and outputting the relative speed value as the moving speed of the vehicle based on the result of the determination, or outputting the relative speed value after performing a calculation process that takes into account the wraparound of the speed information,
the predetermined range of distance values is set to approximately half of a range on the radar device side of a ground surface from a position where the radar device is orthogonally projected onto the ground surface to an intersection point between the front direction and the ground surface, when the radar device is installed on the vehicle such that the front direction of the radar device is at a depression angle ;
the predetermined range in which the value of the relative velocity is smaller than the relative velocity value and the predetermined range in which the value of the relative velocity is larger than the relative velocity value have the same size and are set to a range of approximately 1/10 of the maximum detectable velocity of the radar device.
A method for detecting a moving speed. As the characteristic of the combination data, among the combination data in which the distance value is within the predetermined range, the number of combination data in which the relative velocity value is within the predetermined range smaller than the relative velocity value and the number of combination data in which the relative velocity value is within the predetermined range larger than the relative velocity value are counted.
5. The method for detecting a moving speed according to claim 4. As the characteristic of the combination data, an average value of the distances of the combination data in which the value of the relative velocity is smaller than the relative velocity value and an average value of the distances of the combination data in which the value of the relative velocity is larger than the relative velocity value and ...
5. The method for detecting a moving speed according to claim 4.