JP7555666B2 - 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 invention described in claim 1 is a moving speed detection device comprising: a radar unit that emits a transmission wave, receives a reflected wave of the transmission wave that is reflected by an object and returns, and outputs radar data; a signal processing unit that performs frequency analysis of the radar data to generate a frequency spectrum, and calculates the distance and relative speed to the object to generate combined data of the distance, the relative speed, and the reception strength in the frequency spectrum; a reception strength integration unit that integrates the reception strength for each value of the relative speed using only the combined data in which the distance value is within a predetermined range, to calculate an integrated reception strength value for each value of the relative speed; a moving speed estimation unit that identifies the value of the relative speed corresponding to the maximum value of the integrated reception strength value; and a reliability determination unit that calculates a speed reliability based on the relationship between the maximum value of the integrated reception strength value and at least an average value of the integrated reception strength value excluding the maximum value, wherein the identified value of the relative speed is output as the moving speed of the device itself, and the value of the moving speed of the device itself is not updated for a predetermined period of time depending on the value of the speed reliability.

The invention described in claim 2 is the moving speed detection device described in claim 1 , characterized in that the radar data is data acquired using a frequency modulated continuous wave radar.

The invention described in claim 3 is a method for detecting a moving speed, comprising the steps of: performing frequency analysis of radar data output from a radar device that emits a transmission wave and receives a reflected wave that is returned after the transmission wave is reflected by an object, generating a frequency spectrum, and calculating a distance and relative speed to the object to generate combined data of the distance, the relative speed, and the receiving strength in the frequency spectrum; integrating the receiving strength for each value of the relative speed using only the combined data in which the distance value is within a predetermined range to calculate an integrated receiving strength value for each value of the relative speed; identifying a value of the relative speed that corresponds to a maximum value of the integrated receiving strength value; and calculating a speed reliability based on a relationship between the maximum value of the integrated receiving strength value and at least an average value of the integrated receiving strength value excluding the maximum value, wherein the identified value of the relative speed is set as the moving speed of the device itself, and the value of the moving speed of the device itself is not updated for a predetermined period of time depending on the value of the speed reliability.

The invention described in claim 4 is the moving speed detection method described in claim 3 , characterized in that the radar data is data acquired using a frequency modulated continuous wave radar.

According to the invention of claim 1 and claim 3 , since the moving speed of the radar device itself can be estimated based on the radar data, by installing the radar device, it becomes possible to know the moving speed of various equipment, devices, vehicles, facilities, etc. from only the reception data of one receiving antenna system. According to the invention of claim 1 and claim 5, in particular, the moving speed of the device itself is estimated using the integrated value of the reception intensity for each value of the relative speed calculated using only data whose distance value is within a predetermined range, so that it is possible to prevent erroneous estimation and more accurately estimate the moving speed of the device itself in various environments.

According to the inventions described in claims 1 and 3 , it is possible to prevent the output of abnormal values of the estimated moving speed when the reception strength is significantly reduced due to external disturbances, etc., and it is possible to avoid sudden fluctuations in the estimated value of the moving speed and maintain the continuity of the estimated value of the moving speed. In turn, it is possible to improve the reliability of the technology for estimating the moving speed by suppressing the effect on the estimated value of the moving speed caused by a short-term reduction in reception strength.

According to the invention as recited in claim 2 or claim 4 , the above-mentioned advantageous effects can be achieved by combining with a frequency modulated continuous wave radar.

1 is a functional block diagram showing a schematic configuration of a moving speed detection device according to an 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 according to an embodiment of the present invention. 1A is a diagram showing an example of VR data output from a signal processing unit, and FIG. 1B is a diagram showing the relationship between the relative speed and the integrated value of the received intensity for the VR data of FIG. 1A is a diagram showing an example of setting an intensity integration distance range for VR data output from a signal processing unit, and FIG. 1B is a diagram showing the relationship between relative speed and received intensity integration value when the intensity integration distance range is taken into account for the VR data of FIG. FIG. 11 is a diagram for explaining the content of calculation of speed reliability. 10 is a flowchart showing another processing procedure in the moving speed detection device of FIG. 1 and also showing a processing procedure of a moving speed detection method according to another embodiment of the present invention.

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

Figure 1 is a functional block diagram showing the schematic configuration of a moving speed detection device 1 according to an embodiment of the present invention. Figure 2 is a flowchart showing the processing procedure in the moving speed detection device 1 and the processing procedure of the moving speed detection method according to an 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 integration unit 5, a moving speed estimation unit 6, and a reliability determination unit 7. For example, as merely one example, the moving speed detection device 1 is mounted on a vehicle such as a train or 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 using 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 this 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 to generate combined data of the distance R, the relative speed V, and the receiving strength I in the frequency spectrum; a receiving strength integration unit 5 that integrates the receiving strength I for each value of the relative speed V using only the combined data in which the value of the distance R is within a predetermined range to calculate the receiving strength integrated value Is for each value of the relative speed V; and a moving speed estimation unit 6 that identifies the value Vm of the relative speed V corresponding to the maximum value Ismax of the receiving strength integrated value Is (see FIG. 1).

The moving speed detection device 1 according to this embodiment further includes a reliability determination unit 7 that calculates a speed reliability I R based on the relationship between the maximum value I of the integrated reception strength value I and an average value _I of the integrated reception strength value I excluding at least the maximum value I , and is configured not to update the value of the moving speed of the device itself for a predetermined period of time according to the value of the speed reliability I _R (see FIG. 1).

The method for detecting the moving speed according to this embodiment includes the steps 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 reflected by an object, to generate a frequency spectrum; calculating the distance R and relative velocity V to the object to generate combined data of the distance R, the relative velocity V, and the reception intensity I in the frequency spectrum (steps S1 to S4); integrating the reception intensity I for each value of the relative velocity V using only the combined data in which the value of the distance R is within a predetermined range to calculate the integrated reception intensity value Is for each value of the relative velocity V (step S5); and identifying the value Vm of the relative velocity V that corresponds to the maximum value Ismax of the integrated reception intensity value Is (step S6) (see FIG. 2).

The method for detecting the moving speed according to this embodiment further includes a process (step S7) of calculating a speed reliability I _R based on the relationship between the maximum value I of the integrated reception strength value I and an average value I of the integrated reception strength value I excluding at least the maximum value I max , and is configured not to update the value of the moving speed of the device itself for a predetermined period of time according to the value of the speed reliability I _R (steps S8, S10, S11) (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 a radar scan using a radar method such as FMCW (Frequency Modulated-Continuous Wave) method.

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 sections of 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, with 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 a detailed description 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 which the horizontal axis represents relative velocity 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.

Here, the VR data (V, R, I) includes a speed component that corresponds to (in other words, is equivalent to) the moving speed of the moving speed detection device 1 itself, which is caused by reflected waves from surrounding stationary objects (for example, the ground/road surface, structures, or equipment fixedly installed relative to the ground/land; referred to as "stationary targets"). In this invention, the moving speed of the moving speed detection device 1 itself is estimated by focusing on the reflected waves from the stationary targets. 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 stationary target.

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 strength integration unit 5 uses a set of VR data (V, R, I) to integrate the value of reception strength I for each value of relative speed V to calculate an integrated reception strength value Is for each value of relative speed V. The integrated reception strength value Is is the integrated value of reception strength I in the direction of distance R for each value of relative speed V in a VR plane as shown in FIG. 3, which is configured by a set of VR data (V, R, I). If necessary, the reception strength integration unit 5 may divide the value of relative speed V into a predetermined range and integrate the value of reception strength I for each speed rank (in other words, speed bin).

Figure 3(B) shows a set of combined data (V, Is) of relative velocity V and integrated reception intensity value Is, calculated using the set of VR data (V, R, I) shown in Figure 3(A). In Figure 3(B), the horizontal axis shows relative velocity V, and the vertical axis shows integrated reception intensity value Is.

In FIG. 3(B), peak A is a peak related to the received strength of reflected waves from an object near the radar unit 3 (particularly the transmitting antenna and receiving antenna), for example, reflected waves from a part of the vehicle structure. In this case, the object is moving together with the radar unit 3, so the value of the relative velocity V is 0, and therefore the peak appears at the position where the value of the relative velocity V on the horizontal axis is 0.

On the other hand, peak B is a peak related to the reception strength of the reflected wave from a stationary target, and corresponds to the movement speed of the moving speed detection device 1 itself. When the moving speed detection device 1 and a surrounding object are moving relatively closer to each other, the peak related to the reception strength corresponding to the movement speed of the moving speed detection device 1 itself appears in a region where the value of the relative speed V is negative (it can also be made to appear in a positive region depending on the calculation formula used).

From the above, in order to determine the relative speed of the device with respect to a stationary target, it is necessary to exclude the received strength of reflected waves from objects/structures in the vicinity of the radar unit 3 that are moving together with the radar unit 3.

In addition, the stationary targets that are used as a reference when calculating the relative speed of the device are not distributed over the entire range of the distance R calculated in the processing of step S3. For this reason, if the value of the reception intensity I is integrated for each value of the relative speed V for the entire range of the distance R calculated in the processing of step S3 for a set of VR data (V, R, I), a problem occurs in that a large amount of noise is integrated, resulting in a small signal-to-noise ratio.

Therefore, in this invention, when calculating the reception intensity integrated value Is, the value of the reception intensity I is integrated for each value of the relative speed V within a specific range of the distance R calculated in the processing of step S3. The range of the distance R when calculating the reception intensity integrated value Is is called the "intensity integrated distance range."

Specifically, when calculating the received intensity integrated value Is, the directivity of the transmitting/receiving antennas is taken into consideration, as well as the following items, and the range of the distance R is then limited and the intensity integrated distance range is appropriately set to an appropriate range.
a) Excluding the range in which there is an object that exists in the vicinity of the radar unit 3, moves together with the moving speed detection device 1, and the value of the relative speed V with respect to the moving speed detection device 1 becomes zero.
a) Excluding an area where it is clear that there is an object moving relative to the ground/land. For example, when the moving speed detection device 1 is mounted on a railway and estimates the traveling speed of the railway, the area where other railways run (e.g., the area of adjacent tracks) is excluded, or when the moving speed detection device 1 is mounted on an automobile and estimates the traveling speed of the automobile, the area where other automobiles run (e.g., the area of adjacent lanes) is excluded.
c) Excluding ranges where there are no stationary targets or where the received strength of the reflected waves is extremely weak even if a stationary target is present.

For the intensity integration distance range, only a lower limit may be set for the range of distance R (i.e., only the values of reception intensity I of VR data whose values of distance R are equal to or greater than a predetermined value are integrated), only an upper limit may be set (i.e., only the values of reception intensity I of VR data whose values of distance R are equal to or less than a predetermined value are integrated), or both a lower limit and an upper limit may be set (i.e., only the values of reception intensity I of VR data whose values of distance R are equal to or greater than a predetermined value and less than a predetermined value are integrated).

For the VR data (V, R, I) shown in Figure 3(A), if the intensity integration distance range is set as shown in Figure 4(A) and the received intensity integration value Is is calculated, the result will be as shown in Figure 4(B). In the example shown in Figure 4, the lower limit of the intensity integration distance range is set to 12 m and the upper limit is set to 30 m, just as an example.

In the example shown in FIG. 4(B), there is no peak (peak A in FIG. 3(B)) in the reception strength of the reflected waves from objects near the radar unit 3 (particularly the transmitting antenna and receiving antenna), but peak B (see also FIG. 3(B)) in the reception strength of the reflected waves from the stationary target appears. In other words, the influence of objects near the radar unit 3 is eliminated, and the S/N ratio of the stationary target can be increased, so that the relative speed of the device itself can be accurately calculated, and ultimately the moving speed of the moving speed detection device 1 itself can be accurately estimated.

The reception intensity integration unit 5 sets an intensity integration distance range for the VR data (V, R, I), integrates the value of the reception intensity I for each value of the relative velocity V using only the VR data (V, R, I) whose distance R value falls within the intensity integration distance range, and outputs a set of data (V, Is) consisting of a combination of the relative velocity V and the reception intensity integration value Is. The data (V, Is) output from the reception intensity integration unit 5 is called "reception intensity integration value data."

The moving speed estimation unit 6 uses the set of reception strength integrated value data (V, Is) output from the reception strength integration unit 5 to estimate the moving speed of the moving speed detection device 1 itself (step S6).

The moving speed estimation 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 combined with the identified maximum value Ismax of the integrated reception strength value Is.

Here, the value Vm of the relative speed V to be identified as the moving speed of the moving speed detection device 1 itself is the relative speed to surrounding stationary objects that reflect the transmitted waves (e.g., structures or equipment that is fixedly installed on the ground/land; i.e., stationary targets). However, in an environment where stationary targets cannot be detected, or an environment where stationary targets can be detected but the reception strength is below the noise level, a speed at which a stationary target does not actually exist, in other words, a speed corresponding to a reflected wave that is not from a stationary target, may be erroneously detected as the moving speed of the moving speed detection device 1 itself.

Therefore, in this embodiment, a reliability determination unit 7 is provided as a mechanism for suppressing the influence on the estimated value of the moving speed when the value of the relative speed V corresponding to the reflected wave not from a stationary target is erroneously detected as the moving speed of the moving speed detection device 1 itself.

The reliability determination unit 7 determines the reliability of the value Vm of the relative speed V output from the moving speed estimation unit 6 as the moving speed of the moving speed detection device 1 itself, and determines how to handle the value Vm of the relative speed V. The reliability determination unit 7 includes a reliability calculation unit 71, a reliability evaluation unit 72, and a hold determination unit 73.

The reliability calculation unit 71 calculates a speed reliability I _R as an index for evaluating the reliability of the value V m of the relative speed V as the moving speed of the moving speed detection device 1 itself (step S7).

Specifically, the reliability calculation unit 71 calculates the speed reliability I _R [dB] based on the distribution of the integrated reception strength value Is for each value of the relative speed V, using the following formula 1. In formula 1, Ismax is the maximum value of the integrated reception strength value Is, that is, the value of the integrated reception strength value Is combined with the value Vm of the relative speed V in the set of integrated reception strength value data (V, Is), and Isavg is the average value of the integrated reception strength values Is excluding Ismax (see FIG. 5).
(Math. 1) I _R = 20×log ₁₀ (Ismax/Isavg)

When calculating the average value Isavg of the integrated reception strength value Is, in addition to the maximum value Ismax of the integrated reception strength value Is, the value of the integrated reception strength value Is corresponding to the value of the relative speed V near the value Vm of the relative speed V corresponding to the maximum value Ismax may also be excluded. For example, when the value of the integrated reception strength value Is is integrated for each speed bin, the value of the integrated reception strength value Is of the speed bin on either side of the speed bin corresponding to the maximum value Ismax of the integrated reception strength value Is may also be excluded, or the value of the integrated reception strength value Is of the speed bin on either side of the speed bin corresponding to the maximum value Ismax of the integrated reception strength value Is may also be excluded.

The reliability evaluation unit 72 evaluates the reliability of the value Vm of the relative speed V output from the moving speed estimation unit 6 as the moving speed of the moving speed detection device 1 itself, based on the speed reliability I _R calculated by the reliability calculation unit 71 (step S8).

Specifically, when the value of the speed reliability I _R is greater than the reliability threshold T _R (step S8: Yes), the reliability evaluation unit 72 outputs the value Vm of the relative speed V output from the moving speed estimation unit 6 as the moving speed of the moving speed detection device 1 itself, and stores the value Vm of the relative speed V as the hold relative speed value _VH (specifically, for example, stores it in the ROM 23, etc.), and sets the value of the hold count C to 0 (step S9). After that, the reliability evaluation unit 72 returns the processing procedure for detecting the moving speed to the processing of step S1.

On the other hand, if the value of the speed reliability I _R is equal to or less than the reliability threshold T _R (step S8: No), the reliability evaluation unit 72 outputs the hold relative velocity value V _H as the moving speed of the moving speed detection device 1 itself, and also adds 1 to the value of the hold count C (step S10).

In other words, when the value of the speed reliability I _R is equal to or lower than the reliability threshold T _R (step S8: No), the value Vm of the relative velocity V estimated based on the set of VR data (V, R, I) generated from the radar data acquired by the radar scan in question (step S1) and output from the movement speed estimation unit 6 is not output as the movement speed of the movement speed detection device 1 itself, but the value of the movement speed of the movement speed detection device 1 itself in the previous processing is held (i.e., the value of the movement speed of the movement speed detection device 1 itself is not updated).

The reliability threshold T _R [dB] is not limited to a specific value, but is appropriately set to an appropriate value taking into consideration the characteristics associated with the output of the radar unit 3 and whether the radar data is received in a good condition with no (or few) disturbances and in which a peak in the reception intensity corresponding to an object reflecting the transmission wave can accurately appear, or whether the radar data is received in a condition that cannot be considered good due to disturbances and in which a peak in the reception intensity corresponding to an object reflecting the transmission wave cannot accurately appear. Specifically, the reliability threshold T _R [dB] may be set to an appropriate value within the range of about 2 to 8 [dB], for example, as just one example.

The hold determination unit 73 determines whether or not to continue holding the value of the movement speed of the movement speed detection device 1 itself based on the value of the hold count C (step S11).

Specifically, when the value of the hold count C is equal to the hold threshold T _C (step S11: Yes), the hold determination unit 73 releases the hold state of the value of the moving speed as a response to the case where the value of the speed reliability I _R is equal to or less than the reliability threshold T _R , stores the value Vm of the relative speed V estimated based on the set of VR data (V, R, I) in the radar scan in question (step S1) and output from the moving speed estimation unit 6 as the hold relative speed value V _H , and resets the value of the hold count C to 0 (step S12). After that, the hold determination unit 73 returns the processing procedure for detecting the moving speed to the processing of step S1.

On the other hand, if the value of the hold count C is not equal to the hold threshold _Tc (step S11: No), the hold determination unit 73 returns the procedure for detecting the moving speed to the process of step S1. As a result, the moving speed of the moving speed detection device 1 itself is not updated for a predetermined period of time.

The hold threshold value T _C is not limited to a specific value, but is set to an appropriate value taking into consideration the sampling time width per radar scan and the prevention of a situation in which an abnormal value of the relative velocity V is held continuously due to an occurrence of speed hijacking or the like.

The above-mentioned moving speed detection device 1 and moving speed detection method can estimate the moving speed of the radar device (radar unit 3) itself 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 received data of one receiving antenna system. The above-mentioned moving speed detection device 1 and moving speed detection method estimate the moving speed of the device itself using the reception intensity integrated value Is for each value of the relative speed V, which is calculated using only data whose distance R value is within the intensity integrated distance range, in particular, so that it is possible to prevent erroneous estimation and more accurately estimate the moving speed of the device itself in various environments.

According to the above-mentioned moving speed detection device 1 and moving speed detection method, and also by the processing by the reliability determination unit 7 (i.e., the processing of steps S7 to S12), it is possible to prevent the output of abnormal values of the estimated moving speed when the reception strength is significantly reduced due to disturbances, etc., and it is possible to avoid sudden fluctuations in the estimated value of the moving speed and maintain the continuity of the estimated value of the moving speed, and ultimately to improve the reliability of the technology for estimating the moving speed by suppressing the effect of a short-term decrease in reception strength on the estimated value of the moving speed.

Although the embodiment of the present invention has been described above, the specific configuration is not limited to the above embodiment, and even if there are design changes within the scope of the invention that do not deviate from the gist of the invention, they are included in the invention.

Specifically, in the above embodiment, the FMCW method is used as the radar method, but the use of the FMCW method as the radar method is not a required configuration for this invention, and any radar method may be used as long as it is possible to create the VR data (V, R, I) in the above embodiment. In this respect, the specific configurations of the radar unit 3 and signal processing unit 4 in the above embodiment are not limited to those in the above embodiment.

In addition, in the above embodiment, the reliability determination unit 7 is provided to determine the reliability of the value Vm of the relative speed V as the moving speed of the moving speed detection device 1 itself, but the processing by the reliability determination unit 7 (i.e., the processing of steps S7 to S12) is not an essential component of this invention, and the moving speed detection device 1 may specify the value Vm of the relative speed V by the moving speed estimation unit 6 (step S6) and output it as the moving speed of the moving speed detection device 1 itself.

In addition, in the above embodiment, the speed reliability I _R [dB] is calculated by the formula 1, but the method of calculating the speed reliability I _R is not limited to the formula 1. Specifically, for example, the common logarithm may not be taken for the maximum value Ismax or the average value Isavg of the integrated reception intensity value Is.

Furthermore, when the value of the speed reliability I _R is equal to or smaller than the reliability threshold T _R (step S8: No), in addition to the above embodiment, as the process of step S10, the reliability evaluation unit 72 may output, as the moving speed of the moving speed detection device 1 itself, a value V _N obtained by weighting the hold relative speed value V _H and the relative speed value V m with weighting coefficients W _H and W m determined according to the value of the speed reliability I _R in accordance with the following Equation 2 (note that, as the process of step S10, 1 is further added to the value of the hold count C) (see FIG. 6 ).
(Math. 2) V _N = (W _H ×V _H +Wm × Vm)/(W _H +Wm)

In this case, the moving speed detection device 1 further includes a reliability determination unit 7 which calculates the speed reliability I _R based on the relationship between the maximum value I max of the integrated reception strength value I and the average value I savg of the integrated reception strength value I excluding at least the maximum value I max , and outputs a value V _N calculated by taking a weighted average of the past moving speed value (specifically, the hold relative speed value V _H ) and the latest moving speed value (specifically, the relative speed V value V m ) using weighting coefficients W _H and W _m determined according to the value of the speed reliability I R as the moving speed of the device itself.

In Equation 2, the weighting coefficient W _H applied to the hold relative velocity value V _H is determined according to the value of speed reliability I _R for the value Vm of the relative velocity V stored as the hold relative velocity value V _H , and the weighting coefficient W m applied to the value Vm of the relative velocity V is determined according to the value of speed reliability I _R for the value Vm of the relative velocity V. In this case, the relationship between the value of the speed reliability I _R and the values of the weighting coefficients W _H and W m is basically determined in advance as a relationship in which the values of the weighting coefficients W _H and W m become larger as the value of the speed reliability I _R becomes larger, specifically, for example, as a function for calculating the values of the weighting coefficients W _H and W m using the value of the speed reliability I _R as an explanatory variable.

1 Movement speed detection device 2 Control unit 21 Central processing unit 22 ROM
23 RAM
REFERENCE SIGNS LIST 3 Radar section 31 Transmitter section 32 Receiver section 4 Signal processor section 41 Frequency analyzer section 42 Distance calculator section 43 Speed calculator section 5 Reception intensity integrator section 6 Travel speed estimator section 7 Reliability determiner section 71 Reliability calculator section 72 Reliability assessor section 73 Hold determiner section

Claims (4)

a radar unit that emits a transmission wave, receives a reflected wave that is the transmission wave reflected by an object and returns, 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 to the object to generate combined data of the distance, the relative velocity, and the reception intensity in the frequency spectrum;
a reception strength integrating unit that integrates the reception strength for each value of the relative speed by using only the combination data in which the distance value is within a predetermined range, and calculates an integrated reception strength value for each value of the relative speed;
a moving speed estimating unit that identifies a value of the relative speed corresponding to a maximum value of the integrated reception strength value;
a reliability determination unit that calculates a speed reliability based on a relationship between the maximum value of the integrated reception strength value and at least an average value of the integrated reception strength value excluding the maximum value ,
outputting the determined value of the relative speed as a moving speed of the own device;
not updating the value of the moving speed of the own device for a predetermined period of time according to the value of the speed reliability;
A moving speed detection device characterized by: The radar data is data acquired using a frequency-modulated continuous wave radar.
2. The moving speed detection device according to claim 1 . A process of performing frequency analysis of radar data output from a radar device that emits a transmission wave and receives a reflected wave of the transmission wave that is reflected by an object, generating a frequency spectrum, and calculating a distance and a relative speed to the object to generate combined data of the distance, the relative speed, and the reception intensity in the frequency spectrum;
A process of integrating the reception strength for each value of the relative speed by using only the combination data in which the distance value is within a predetermined range, and calculating an integrated reception strength value for each value of the relative speed;
A process of identifying a value of the relative velocity corresponding to a maximum value of the integrated reception intensity value;
and calculating a speed reliability based on a relationship between the maximum value of the integrated reception strength value and an average value of the integrated reception strength value excluding at least the maximum value ,
The specified value of the relative speed is set as a moving speed of the own device,
not updating the value of the moving speed of the own device for a predetermined period of time according to the value of the speed reliability;
A method for detecting a moving speed. The radar data is data acquired using a frequency-modulated continuous wave radar.
4. The method for detecting a moving speed according to claim 3 .