JPH112677A - Radar device for vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve detection performance for a long distance obstacle without degrading the tracking performance for a short distance vehicle by forming a weight with a frequency around a prediction peak frequency for low frequency region, calculating the averaging of signal intensity at every past frequency and forming a weight with the value for high frequency region. SOLUTION: A frequency range dividing weight forming means 12 forms a weight with a frequency around a prediction peak frequency from a prediction peak frequency determining means 7 for low frequency region, and forms a weight with averaging of signal intensity at every frequency stored in the past in a signal intensity memory means 11 for high frequency region. A peak frequency determining means 9 gives weight based on the signal intensity at every frequency from a signal intensity measuring means 6 and determines a peak frequency. A distance/velocity calculation means 10 outputs the distance and velocity of the obstacle using the peak frequency. For low frequency region, a peak frequency around a prediction peak frequency is efficiently detected and for high frequency region, a peak frequency can be detected by suppressing noise level.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an in-vehicle radar apparatus for performing a triangular frequency modulation on a transmission signal of a continuous wave radar and simultaneously receiving a reflected signal from an obstacle to detect a distance and a speed. It is.

[0002]

2. Description of the Related Art A conventional radar apparatus of this type is disclosed in Japanese Patent Application Laid-Open No. Hei 5-333143. FIG. 4 is a block diagram showing a configuration of a conventional on-vehicle radar device.
FMCW transmitting means 1), an antenna 2 capable of transmitting a signal transmitted from the FMCW transmitting means 1 as a radio wave, and receiving a reflected and returned signal; Mixing means 3 for mixing the signal and the signal received by the antenna 2 to output a beat signal, and analog / digital signal converting means (hereinafter, A / D) for converting the beat signal output from the mixing means 3 into discrete values. Conversion means 4), a Fourier transformation means 5 for transforming the beat signal converted into a discrete value by the A / D conversion means 4 into a frequency using Fourier transformation or the like, and a beat signal from the output of the Fourier transformation means 5 A signal strength measuring means 6 for measuring a signal strength for each frequency; and a predicted peak frequency determining means for predicting a frequency to be a peak frequency and outputting a predicted peak frequency. 7, weight forming means 8 for forming a weight with frequencies around the predicted peak frequency which is the output of the predicted peak frequency determining means 7, and weight forming means 8 for the signal strength for each frequency which is the output of the signal strength measuring means 6. A peak frequency determining means 9 for determining a peak frequency by weighting with the output of the above, and a distance / speed calculation for calculating a distance and a speed from the peak frequency output from the peak frequency determining means 9 to an obstacle corresponding to the peak frequency. Means 10 are provided.

[0003]

However, in the conventional radar device having the structure shown in FIG. 4, even if the peak frequency determining means 9 can easily detect the peak frequency in the low frequency region where the noise level is small. In addition, there is a problem that it is difficult to detect a peak frequency in a high frequency region having a large noise level. In addition, since the noise level is too high, there is a problem that it is difficult to detect an obstacle in a high frequency region even if weighting is performed using the predicted peak frequency.

The present invention solves the above-mentioned conventional problem. In the high frequency region of the beat frequency, weighting is performed by averaging the signal intensities measured in the past for each frequency, and the noise level in the high frequency region is reduced. It is another object of the present invention to provide an on-vehicle radar device capable of improving the detection performance for a long-range obstacle that is difficult to detect without impairing the short-range vehicle tracking performance.

[0005]

In order to achieve the above object, an on-vehicle radar device according to the present invention comprises a signal strength storage means for storing a signal strength for each frequency; And a frequency range-based weight forming means for calculating an average of signal intensities for each frequency in the past in the signal strength storing means for the high frequency region and forming a weight with the calculated value. It is configured as follows.

When there is a predicted peak frequency in a high frequency region, the frequency range-based weight forming means weights the frequency around the predicted peak frequency together with the weight of the average value of the signal intensities of the past frequencies. It is configured as follows.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The invention according to claim 1 of the present invention provides an FMCW transmitting means for frequency-modulating a carrier wave in a triangular shape and outputting the same, and a signal output from the FMCW transmitting means. An antenna for receiving a signal reflected back from an obstacle; a mixing means for mixing the signal received by the antenna with a signal output from the FMCW transmitting means to output a beat signal; Analog / digital signal converting means for converting the beat signal output from the digital signal into a discrete value, a Fourier transform means for converting the beat signal converted into a discrete value by the analog / digital signal converting means into a frequency and outputting the frequency, Signal strength measuring means for measuring and outputting the signal strength for each frequency from the output of the Fourier transform means; and for each frequency output from the signal strength measuring means. Signal strength storage means for storing the signal strength of, the predicted peak frequency determining means for predicting the peak frequency, in a low frequency region weights are formed at frequencies around the predicted peak frequency which is the output of the predicted peak frequency determining means; In a high frequency region, a weight forming means for each frequency range for forming a weight by an average value of signal strengths for each frequency stored in the past, which is an output of the signal strength storing means, and a frequency which is an output of the signal strength measuring means. Frequency determining means for determining the peak frequency by weighting the signal strength for each frequency based on the output from the frequency range weighting means, the distance from the peak frequency which is the output of the peak frequency determining means to the obstacle And a distance / speed calculating means for outputting at least one of the speed and the speed. Since the peak frequency in the vicinity of expected peak frequency for frequency can be efficiently detected, which can detect the peak frequency by suppressing the noise level for a higher frequency range,
Even if there is an obstacle at a long distance, it is possible to perform good detection while suppressing the influence of noise.

According to a second aspect of the present invention, when the frequency range-based weight forming means includes a predicted peak frequency output from the predicted peak frequency determining means in a high frequency region, the signal strength storage means The weight is formed by the average value of the signal strength for each frequency stored in the past as the output, and the weights of the frequencies around the predicted peak frequency are also formed by overlapping. By this, when the predicted peak frequency is in the high frequency region, it is possible to detect the peak frequency by weighting around the predicted peak frequency, and to suppress the influence of noise on obstacles that are predicted to exist at long distances. Can be detected.

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

FIG. 1 is a block diagram showing a configuration of an on-vehicle radar device for explaining an embodiment of the present invention. In the figure, the same reference numerals are given to the components having the same configuration and the same operation and effect as described in FIG. 4 showing the conventional example.
The present embodiment differs from the configuration of the apparatus of FIG. 4 in that a signal strength storage means 11 for storing the signal strength of each frequency output from the signal strength measurement means 6 and a predicted peak frequency determination means in a low frequency region. Weighting is performed on the frequency around the predicted peak frequency output from the signal 7, and in the high frequency region, weighting is performed using an average value of the signal strengths of the frequencies stored in the past output from the signal strength storage unit 11. Is provided with a frequency range-dependent weight forming means 12 that forms

The operation of the on-vehicle radar device configured as described above will be described.

[0012] In the FMCW transmitting means 1, a carrier frequency-modulated in a triangular shape is output, and the carrier wave is transmitted via the antenna 2. The transmitted carrier wave reflects off an obstacle and is received again by the antenna 2. The received signal and the signal output from the FMCW transmission means 1 are converted into a beat signal by mixing by a mixing means 3, converted into discrete values by an A / D conversion means 4, and Converted to frequency values.

After that, the signal strength of the beat signal converted into the frequency value by the signal strength measuring means 6 is measured for each frequency, and the signal strength for each frequency is stored in the signal strength storing means 11.

On the other hand, the predicted peak frequency determining means 7 predicts the current peak frequency from the previously determined peak frequency and the like. Then, based on the peak frequency predicted by the predicted peak frequency determining means 7 and the signal strength for each frequency stored in the signal strength storing means 11, the frequency range-based weight forming means 12 calculates the vicinity of the predicted peak frequency in the low frequency region. Form a weight at the frequency of
In the high frequency region, the weight is formed by the average value of the signal intensities for each frequency stored in the past, which is the output of the signal intensity storage means 11. This weighting value is multiplied by the signal strength for each frequency obtained by the signal strength measuring means 6,
When the frequency is larger than the threshold value, the frequency is determined as the peak frequency, and the distance and the speed corresponding to the peak frequency are calculated by the distance / speed calculating means 10. Whether to calculate one of the distance and the speed or both of them is appropriately selected.

Next, with reference to the flow chart of FIG. 2, weighting means for each frequency range in the first embodiment of the present invention.
Operation 12 will be described.

First, the band of the beat frequency is divided into N (N is an integer). After the start (S1), 1 is substituted for i in order to determine the weight for the first frequency (S2).
Next, it is determined whether or not the i-th frequency f [T] [i] at the time T is in a low frequency region (S3). If Yes, the process of (S4) is performed. (S7) is performed.

In the process of (S3), if it is determined to be Yes, the predicted peak frequency fp output from the predicted peak frequency determining means 7 and the i-th frequency f [T] [i] at time T are calculated. It is determined whether or not the absolute value of the difference is smaller than a certain value ε (S4), and if Yes, the process of (S5) is performed.
If No, the process of (S6) is performed. In the processing of (S4), if it is determined to be Yes, the i-th frequency f
A value η larger than 1 is substituted for the weight coefficient α [i] of [T] [i] (S5). If it is determined as No in the processing of (S4), the value 1 is substituted for the weight coefficient α [i] of the i-th frequency f [T] [i] (S6).

On the other hand, if it is determined as No in the processing of (S3), j = 1 and Pa = 0 are set (S7). Thereafter, it is determined whether or not j is equal to k (S8). If Yes, the process of (S11) is performed, and if No, the process of (S9) is performed. In the process of (S8), when it is determined that the frequency is no, the frequency f [T−
j] [i], using the signal strength P [Tj] [i], Pa
= (Pa + P [T-j] [i]) / k is substituted (S9), and then j = j + 1 is substituted (S10). Further, in the case of Yes in the processing of (S8), a weighting coefficient α [i] = Pa × ν is set using a constant value ν (S11).

Then, assuming that i = i + 1 (S12), i = N
Is determined (S13). If Yes, the process of (S14) is performed. If No, the process of (S3) is performed. (S1
If it is determined as Yes in 3), the calculated weighting factors α [1], α [2], α [3],..., Α [N] are output.
(S14), ends (S15).

By doing so, the peak frequency near the predicted peak frequency can be efficiently detected in the low frequency region, and the peak frequency in the high frequency region can be efficiently detected.
Since the peak frequency can be detected with the noise level suppressed, it is possible to detect the obstacle with the influence of the noise even if there is a distant obstacle.

FIG. 3 is a flow chart showing the operation of the frequency domain weight forming means of the on-vehicle radar device for explaining the second embodiment of the present invention.

In FIG. 3, this flow is obtained by deleting the processing of (S11) from the flow chart of FIG.
7, the processing of S18 is added, and S1 to S10,
Since each process in S12 to S15 performs the same operation as S1 to S10 and S12 to S15 described with reference to the flowchart of FIG. 2, detailed description thereof will be omitted.

If it is determined to be Yes in (S8) of FIG. 3, the predicted frequency fp which is the output of the predicted peak frequency determining means 7 and the i-th frequency f [T] at time T
It is determined whether or not the absolute value of the difference from [i] is smaller than a fixed value ε (S16). If Yes, the process of (S17) is performed, and if No, the process of (S18) is performed. Then, in (S16), Y
If it is determined to be es, the weight coefficient of the i-th frequency f [T] [i] is set to α [i] = Pa × η × ν (S17). In (S16), when it is determined that the frequency is No, the i-th frequency f
The weighting coefficient of [T] [i] is set to α [i] = Pa × ν (S18).

In this way, when the predicted peak frequency is in the high frequency region, the peak frequency can be detected by weighting around the predicted frequency.
Further, it is possible to detect an obstacle whose existence is predicted at a long distance while suppressing the influence of noise.

[0025]

As described above, according to the on-vehicle radar device of the present invention, in the low frequency region of the beat signal, the frequency predicted to have a peak is weighted to detect the peak frequency, and the high frequency is detected. For the region, by performing weighting by averaging the signal intensity for each frequency immediately before detection and performing peak frequency, obstacles that are being tracked at a short distance can be easily detected, and the noise level is high. Obstacles at long distances, which are difficult to detect, can be detected with high probability.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of an on-vehicle radar device for describing an embodiment of the present invention.

FIG. 2 is a flowchart relating to the operation of a frequency range-based weight forming unit according to the first embodiment of the present invention.

FIG. 3 is a flowchart illustrating an operation of a frequency range-based weight forming unit in a vehicle-mounted radar device for describing a second embodiment of the present invention.

FIG. 4 is a block diagram for explaining a configuration of a conventional on-vehicle radar device.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... FMCW transmission means, 2 ... Antenna, 3 ... Mixing means, 4 ... A / D conversion means, 5 ... Fourier transformation means,
6: Signal strength measuring means, 7: Predicted peak frequency determining means, 9: Peak frequency determining means, 10: Distance / speed calculating means, 11: Signal strength storing means, 12: Frequency range-dependent weight forming means.

Claims (2)

[Claims] 1. A frequency modulation / continuous radar wave transmitting means for frequency-modulating and outputting a carrier wave in a triangular shape in time, and a signal output from the frequency modulation / continuous radar wave transmitting means is transmitted and the obstacle is obstructed. An antenna for receiving the reflected signal; a mixing means for mixing the signal received by the antenna with the signal output from the frequency modulation / continuous radar wave transmitting means to output a beat signal; Analog / digital signal converting means for converting a beat signal output from the means into a discrete value, a Fourier transform means for converting a beat signal converted into a discrete value by the analog / digital signal converting means into a frequency and outputting the frequency, Signal strength measuring means for measuring and outputting the signal strength for each frequency from the output of the Fourier transform means; Signal strength storage means for storing the signal strength for each frequency; predicted peak frequency determining means for predicting the peak frequency; and forming a weight with frequencies around the predicted peak frequency which is the output of the predicted peak frequency determining means in a low frequency region. And in the high frequency region, a frequency range-based weight forming unit that forms a weight with an average value of the signal strength for each frequency stored in the past, which is an output of the signal strength storing unit, and an output of the signal strength measuring unit. A peak frequency determining means for determining a peak frequency by weighting a signal strength for each frequency based on an output from the frequency range-based weight forming means, and an output from the peak frequency determining means to an obstacle. An on-vehicle radar device comprising a distance / speed calculating means for outputting at least one of a distance and a speed. 2. The method according to claim 2, wherein the weighting means for each frequency range stores, when there is a predicted peak frequency output from the predicted peak frequency determining means in a high frequency region, the past output which is the output of the signal strength storing means. 2. The on-vehicle radar according to claim 1, wherein the weight is formed by an average value of the signal intensities of the respective frequencies, and the weights of the frequencies around the predicted peak frequency are also formed in an overlapping manner. apparatus.