WO2006061913A1 - Method and device for measuring distance and speed - Google Patents

Abstract

In order to provide a method and a device for measuring distance and speed capable of determining a distance and a relative speed accurately without relying upon the relation between a distance to and a relative speed with an object, the inventive radar comprises a section (1) for delivering an emission wave to an object, a receiving section (2) generating a beat signal by receiving a reflection wave from the object, and a control section (3) for generating the waveform pattern of the emission wave and calculating a distance to or a relative speed with the object from the beat signal, wherein the control section (3) comprises a waveform pattern generating section (10), and a distance and speed calculating section (11) consisting of a candidate calculating section (12) and a specific processing section (13).

Description

 Specification

 Method and apparatus for measuring distance and speed

 Technical field

 TECHNICAL FIELD [0001] The present invention relates to a method and apparatus for measuring a distance and speed from an object using an FMCW radar.

 Background art

 [0002] In general, FMCW radars have been put into practical use as radars that measure the distance to a target and the relative speed. For example, it is used as an on-vehicle radar, detects a vehicle in front of the vehicle, finds distance, relative speed, direction, etc., and performs vehicle control and alarm output based on these information.

 [0003] This FMCW method is generated when a reflected wave obtained by radiating a radio wave (hereinafter referred to as "launch wave" t), which is an FM modulation of a continuous wave signal, and a launch wave are mixed. The frequency of the beat signal (hereinafter referred to as “beat frequency”) is measured, and two types of beat frequency are determined by the time until the reflected wave returns (proportional to the distance) and the Doppler effect vs. the velocity) This is a method to obtain distance and relative speed.

 [0004] FIG. 1A (a) shows the emitted wave and reflected wave in the FMCW system, and FIG. 1A (b) shows the waveform of the beat signal at that time.

 The solid line in Fig. 1A (a) indicates the emission wave, and the broken line indicates the reflected wave. In addition, the reflected wave shown in the figure shows a reflected wave when the object is a moving body, and has a waveform that is shifted in the direction of the arrow shown in the figure by the Doppler effect.

 [0005] Fig. LA (b) shows the beat signal obtained by mixing the emitted wave and reflected wave shown in Fig. 1A (a), and has a constant frequency bl (for example, period (1)) and b2 (for example, Period (2)) is provided.

 [0006] Here, the distance to the object is d [m], the speed of light is c [m / s], and the slope of the frequency change of the emitted and reflected waves shown in Fig. 1A (a) is k [ When the Doppler effect is ignored, the beat frequencies bl and b2 shown in Fig. LA (b) can be obtained from the following equations.

[0007] bl = b2 = k * A t = k * (2 * dZc) Furthermore, if the relative velocity with the object is v [mZs] and the Doppler effect is taken into account, the frequency variation due to the Doppler effect is (2 * vZc) * fO, so the beat frequencies bl and b2 are More.

[0008] bl = (2 * kZc) * d + (2 * fOZc) * v (la)

 b2 = (2 * kZc) * d— (2 * fOZc) * v (lb)

 Here for the sake of simplicity

 D = (2 * kZc) * d, V = (2 * fOZc) * v (2)

 Then, the expressions (la) and (lb) are

 bl = D + V (3a)

 b2 = D-V (3b)

 D and V are obtained as follows by solving equations (3a) and (3b).

[0009] D = (bl + b2) / 2 (4a)

 V = (bl-b2) / 2 (4b)

 Patent Document 1 discloses a device that transmits an FM-CW wave as a launch wave to the front of the vehicle, analyzes the beat signal obtained from the reflected wave, and measures the distance between the vehicle and the vehicle ahead. An apparatus that finds an accurate combination of modulation frequency peaks, even if present, to measure distance and speed between vehicles is disclosed.

[0010] In addition, Patent Document 2 discloses a continuous wave radar, a distance velocity measuring device, and a frequency modulation method that can determine individual distances and relative velocities when there are a plurality of measurement objects. Has been.

 Patent Document 1: Japanese Patent Application Laid-Open No. 07-020233

 Patent Document 2: Japanese Patent Laid-Open No. 2001-337160

 Disclosure of the invention

 However, since the beat frequency is acquired as an absolute value of the difference between the emitted wave and the reflected wave, the acquired beat frequency does not include information on the sign. Therefore, the sign was not considered. Actually, in formulas (3a) and (3b), D and V were obtained on the assumption that D> I V I.

[0012] As a result, the distance to the object and the relative speed satisfy certain conditions (D> IVI) In other cases, there was a problem that accurate distance and relative speed could not be obtained. For example, when IVI is larger than D, that is, when an object existing at a short distance moves at a large relative speed, there is a problem that an accurate distance and relative speed cannot be obtained.

 [0013] The present invention has been made in view of the above-described problems, and the problem to be solved is to obtain an accurate distance and relative speed without depending on the relationship between the distance to the object and the relative speed. It is to provide a distance and speed measuring method and apparatus that can be obtained

[0014] In order to solve the above problems, a distance and speed measurement method using an FMCW radar according to the present invention includes a waveform pattern generation process for generating a waveform pattern having three or more frequency change patterns, and The waveform pattern generated by the waveform pattern generation processing is frequency-modulated to generate a emission wave, and the transmission processing for transmitting the emission wave, and the reception processing for receiving the reflected wave reflected from the object by the emission wave. A beat frequency acquisition process for acquiring the beat frequency corresponding to the pattern by mixing the emitted wave and the reflected wave, and the beat frequency is a first frequency component based on a time delay of the reflected wave and a Doppler A relational force that is an absolute value of the sum or difference with the second frequency component based on one effect, and a distance and speed calculation process for calculating the distance and relative speed of the object. It is a sign.

 [0015] In the distance and speed calculation processing, each beat frequency obtained by the beat frequency acquisition processing is divided into a first frequency component (D) based on the time delay of the reflected wave and a second frequency component based on the Doppler effect (V Since the distance and relative speed of the object are calculated from the relationship between the absolute value of the sum or difference with) and the like, the accurate distance and The relative speed can be obtained.

[0016] Further, in the distance and speed measurement method using the FMCW radar according to the present invention, in the distance and speed calculation process, the gradients of the three frequency change patterns are kl, k2, and k3, and the center. When the frequency is fO and the speed of light is c, the relational expression of the first beat frequency bl and the second beat frequency b2 and the third beat frequency with the first frequency component and the second frequency component bl = I (2 water kl / c) Water d + (2 water fO / c) Water v I

 b2 = I (2 * k2Zc) * d + (2 * fOZc) * v I

 b3 = I (2 water k3 / c) Water d + (2 water fO / c) Water v I

 And a specific process for identifying the distance and relative speed of the object.

[0017] Thereby, in the candidate calculation process, it is possible to calculate a solution candidate for the distance d and relative speed V of the object without being constrained by the constraint condition D> IVI, which has been a precondition in the past. In the identification process, it is possible to identify the correct object distance d and relative velocity V solution.

[0018] Further, the distance and speed measurement method using the FMCW radar according to the present invention includes a waveform pattern including three frequency change patterns of an ascending part, a descending part, and a constant part in the waveform pattern generation process. In the calculation process, the first beat frequency is an absolute value of the sum of the first frequency component and the second frequency component, and the second beat frequency is the first frequency component. Is the absolute value of the difference between the first frequency component and the second frequency component, the candidate calculation processing for calculating solution candidates for the first frequency component and the second frequency component, and the third beat frequency are Based on the relationship that it is the absolute value of the second frequency component, a solution is identified from the solution candidates calculated by the candidate calculation processing, and the identified first frequency component and second frequency component are used. Distance of the object The specific process of calculating the fine relative speed may be provided.

[0019] Further, in the candidate calculation process, the first beat frequency bl, the second beat frequency b2, and the first frequency are set so that the absolute values of the frequency increase and decrease slopes are the same. Relational expression for component D and second frequency component V

 bl = I D + V I

 b2 = I D-V I

 The solution candidate is calculated by solving for the third beat frequency b3.

 b3 = I V I

And the solution candidate that minimizes the distance between the solution candidate and the solution candidate may be identified as the distance and relative speed of the object. [0020] In addition, when two reflected waves are received by the reception process, the specifying process includes four straight lines passing through two solution candidates that are specified as the solution on the DV plane. The value of the intercept on the D-axis or V-axis may be set as a constraint condition to match the four beat frequencies acquired by the beat frequency acquisition process. As a result, it is possible to identify two correct solutions from the solution candidates obtained by the candidate calculation process based on the four beat frequencies acquired by the two reflected wave force beat frequency acquisition processes received by the reception process. Become.

 In addition, when there are two or more reflected waves, the specifying process is performed by using the D-V plane and the intercept value in the D-axis or V-axis of the straight line group that passes through the plurality of solution candidates to be specified. However, it may be a constraint that all the beat frequencies acquired by the beat frequency acquisition process are covered. In addition, the present invention provides a waveform pattern generation unit that generates a waveform pattern having three or more frequency change patterns, and generates a firing wave by frequency-modulating the waveform pattern generated by the waveform pattern generation unit. A transmitting unit that transmits the emission wave, a reception unit that receives a reflected wave reflected from the object by the emission wave, and a beat frequency corresponding to the pattern is obtained by mixing the emission wave and the reflected wave And a relational power that the beat frequency is an absolute value of the sum or difference of the first frequency component based on the time delay of the reflected wave and the second frequency component based on the Doppler effect. And a distance and speed calculation unit that calculates a distance and a relative speed, and a distance and speed measurement device using an FMCW radar.

 [0021] As described above, according to the present invention, a distance and speed measurement method that makes it possible to obtain an accurate distance and relative speed without depending on the relationship between the distance to the object and the relative speed, and An apparatus can be provided.

 Brief Description of Drawings

 FIG. 1A is a diagram showing a conventional example of a emitted wave, a reflected wave, and a beat signal in the FMCW system.

 FIG. 1B is a diagram showing functional blocks of an FMCW radar according to an embodiment of the present invention.

[Fig. 2] Shows the emission wave, reflected wave, and beat signal of the FMCW radar according to this embodiment. FIG.

 FIG. 3 is a flowchart showing processing of a distance and speed calculation unit in the control unit.

 FIG. 4A is a diagram illustrating an example of a relationship of Expressions (5a) to (5c) when bl> b2.

 FIG. 4B is a diagram showing an example of the relationship of equations (5a)-(5c) in the case of bl≤b2.

 FIG. 5 is a diagram showing a relationship between a region targeted in a conventional example and a region targeted in the present invention.

 FIG. 6A is a diagram showing an example of the relationship of equations (5a) to (5c) when two reflected waves are received.

 FIG. 6B is a diagram showing an example of the relationship of equations (5a) to (5c) when two reflected waves are received. BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, embodiments of the present invention will be described with reference to FIGS. 1B to 6B.

 FIG. 1B shows a functional block diagram of the FMCW radar according to the embodiment of the present invention. The radar shown in FIG. 1B includes a transmission unit 1 that transmits a emission wave to an object and a reflected wave from the object. And at least a control unit 3 for generating a wave pattern pattern of the emission wave and calculating a distance from the beat signal and an object relative to the target, a relative speed, and the like.

 [0024] The sending unit 1 includes at least a DZA conversion unit 4, a VCO (voltage control transmission device) 5, and a sending antenna 6. For example, triangular wave data generated by the waveform pattern generation unit 10 is D

Frequency modulation and analog conversion are performed by the ZA converter 4 and output to VC05.

The VC 05 generates a signal force emission wave that has been frequency-modulated by the DZA conversion unit 4, and sends it to the object via the transmission antenna 6.

 The reception unit 2 includes at least a reception antenna 7, a mixing unit 8, and an AZD conversion unit 9, and a reflected wave from the object is received by the reception antenna 7 and output to the mixing unit 8.

The mixing unit 8 mixes the emission wave generated by the VC 05 and the reception wave received by the reception antenna 7 to generate a beat wave and outputs it to the AZD conversion unit 9. Then, the beat signal digitalized by the AZD conversion unit 9 is output to the control unit 3.

The control unit 3 includes at least a waveform pattern generation unit 10 and a distance and speed calculation unit 11 including a candidate calculation unit 12 and a specific processing unit 13. The waveform pattern generation unit 10 generates waveform pattern data transmitted by the transmission unit 1 and outputs the waveform pattern data to the DZA conversion unit 4. Further, the candidate calculation unit 12 constituting the distance and speed calculation unit 11 calculates a solution candidate for the distance and relative speed with respect to the object based on the beat signal from the AZD conversion unit 9, and further specifies the specific processing unit 13 To identify the optimal solution (distance and relative speed) from the solution candidates.

[0028] Fig. 2 (a) shows the emitted wave and reflected wave of the FMCW radar according to the present embodiment. The emitted wave shown in Fig. 2 shows the output waveform of VC05 shown in Fig. 1B. The reflected wave shown in the figure shows the input waveform to the mixing unit 8 shown in FIG. 1B.

 [0029] In addition, the emission wave shown in FIG. 2 is an emission wave as shown in FIG. 2 (a), that is, the rising part of period (1), the falling part of period (2), and the period (3). The waveform pattern data formed by the waveform pattern generation unit 10 constituting the control unit 3 is analog-converted through the DZA conversion unit 4 and further obtained through the VC05.

 [0030] On the other hand, the reflected wave shown in the figure is a received wave obtained when the emitted wave sent from the sending unit 1 is reflected by the object and received by the receiving antenna 7.

 Figure 2 (b) shows the frequency of the beat signal obtained in Fig. 2 (a).

 [0031] The beat signal shown in the figure is obtained by mixing the output waveform (emitted wave) of VC05 shown in Fig. 2 (a) and the reflected wave obtained by reflecting the emitted wave on the object at the mixing unit 8. It is obtained by mixing, and has a beat frequency bl of period (4), a beat frequency b2 of period (5), and a beat signal frequency of period (6).

 [0032] The beat signal shown in the figure is output to the AZD conversion unit 9, digitized, and then output to the control unit 3.

 Then, the distance and speed calculation unit 11 constituting the control unit 3 calculates the distance and relative speed with respect to the object based on the beat frequencies bl, b2, and b3.

FIG. 3 is a flowchart showing the processing of the distance and speed calculation unit 11 in the control unit 3.

When the input signal (beat signal) from the AZD converter 9 is input to the controller 3, step S In 301, the control unit 3 performs processing such as FFT on the input beat signal to obtain the beat frequencies bl, b2, and b3 in the period (4) one (6) shown in FIG. 2 (b). .

When the beat frequency is acquired, the process proceeds to step S 302, and the candidate calculation unit 12 calculates the distance and relative speed of the acquired beat frequency force object.

 Here, the beat frequencies bl, b2, and b3 are the distance to the object d [m], the speed of light c [mZs], and the slopes of the emission and reflected wave modulations shown in Fig. 2 (a). Is k [HzZs] and the relative velocity of the object is v [mZs]

 bl = I (2 * kZc) * d + (2 * fOZc) * v I

 b2 = I (2 * kZc) * d— (2 * fOZc) * v I

 b3 = I (2 water fO / c) Water v I

 Thus, by using the formula (2), the formula (5a), the formula (5b), and the formula (5c) are obtained.

[0035] bl = I D + V I (5a)

 b2 = I D-V I (5b)

 b3 = I V I (5c)

 First, the candidate calculation unit 12 calculates solution candidates for the forces D and V in the equations (5a) and (5b). In other words, Equation (5a) and Equation (5b) are based on the relationship between D and V.

 D = (bl + b2) / 2

 V = (bl-b2) / 2

 And if D <V,

 D = (bl-b2) / 2

 V = (bl + b2) / 2

 It becomes. In addition, in the case of D Kuichi V,

 D = (-bl + b2) / 2

 V = (-bl-b2) / 2

 It becomes.

[0036] In the above case, D is a value proportional to the distance to the object, so that the force cannot be negative and the magnitude relational force of bl and b2 is limited to the following two cases, and bl> For b2, D = (bl + b2) / 2 • · · (6a)

 V = (bl-b2) / 2 • · · (6b)

 Or

 D = (bl-b2) / 2 • · · (7a)

 V = (bl + b2) / 2 • · · (7b)

 And if bl≤b2,

 D = (bl + b2) / 2 • · · (8a)

 V = (bl-b2) / 2 • · · (8b)

 Or

 D = (-bl + b2) / 2 • · · (9a)

 V = (-bl-b2) / 2 • · · (9b)

 It becomes.

 [0037] Therefore, the candidate calculation unit 12 compares the beat frequencies bl and b2 acquired in step S301. If bl> b2, the equations (6a) and (6b), the equations (7a) and (7b ) To calculate (D, V) solution candidates.

 [0038] If the beat frequencies bl and b2 are bl≤b2, using (8a) and (8b), (9a) and (9b), (D, V) solution candidates Is calculated.

 When the solution candidate calculation process is completed, the process proceeds to step S303, and the identification processing unit 13 performs a process of identifying an optimal (correct) solution with the solution candidate power calculated in step S302. However, since the three straight lines generally do not intersect at one point due to measurement errors, the intersection point closer to the straight line in equation (5c) is adopted.

[0039] That is, in the case of bl> b2, using equation (6b) and equation (7b),

 δ 1 = | (bl-b2) / 2-b3 I

 δ 2 = | (bl + b2) / 2-b3 I

 If δ ΐ δ 2, specify (D, V) obtained by Equations (6a) and (6b) as the solution, and if δ 1> δ 2, then Equation (7a) And (D, V) determined by (7b) is identified as the solution.

[0040] Similarly, if bl≤b2, δ 1 = I (bl-b2) / 2 + b3 I

 δ 2 = | (-bl-b2) / 2 + b3 I

 When δ ΐ δ 2, specify (D, V) obtained by equations (8a) and (8b) as the solution, and if δ 1> δ 2, then equation (9a) And (D, V) determined by (9b) is identified as the solution.

 When (D, V) is calculated by the above processing, the distance d and relative velocity V of the object are calculated from the equation (2), and the processing is completed.

 FIG. 4A is a diagram illustrating an example of the relationship of Expressions (5a)-(5c) when bl> b2.

[0042] In the figure, the formula (5a) force is obtained.

 bl = D + V,

 bl = -D-V

 And formula (5b) force is obtained.

 b2 = D-V,

 b2 = -D + V

 Considering that D> 0, the intersection (1) and the intersection (2) are changed to (D, V) by the processing of step S302 shown in FIG. Calculated as a solution candidate.

 [0043] Further, in the same figure, the force of formula (5c) is obtained.

 b3 = V

 b3 = -V

 The intersection (1) and the intersection (2) are identified as the solution of (D, V) from the intersection (1) and the intersection (2) by the process of step S303 shown in FIG.

[0044] FIG. 4B is a diagram illustrating an example of a relationship of Expressions (5a) to (5c) in the case of bl≤b2.

 As with Fig. 4A, formula (5a) force can be obtained.

 bl = D + V,

 bl = -D-V

 And formula (5b) force is obtained.

b2 = DV, b2 = -D + V

 Considering that D> 0, the intersection (3) and the intersection (4) are changed to (D, V) by the process of step S302 shown in FIG. Calculated as a solution candidate.

 [0045] Further, in the same figure, the force of formula (5c) is obtained.

 b3 = V

 b3 = -V

 The intersection (3) and the intersection (4) are identified as the solution of (D, V) from the intersection (3) and the intersection (4) by the process of step S303 shown in FIG.

FIG. 5 is a diagram showing the relationship between the area targeted in the conventional example and the area targeted in the present invention.

 In the past, in Equations (3a) and (3b), the relationship D> I V I was assumed, so the solution was obtained only for region (1) of (D, V) shown in the figure.

 Therefore, for example, even when the original solution is the intersection (5), the intersection (6) is calculated as the solution in the conventional example. Similarly, even if the original solution was the intersection (7), the intersection (8) was calculated as the solution in the conventional example.

 That is, when the distance to the object and the relative speed do not satisfy the condition of D> I V I, there is a problem that an accurate distance and relative speed cannot be obtained.

 For example, when the original solution is the intersection (5) or the intersection (7), calculating the intersection (6) or the intersection (8) as the solution is a distance farther than the original distance and smaller than the original relative velocity. A dangerous situation where the object is close to the distance (D) and the relative speed (IVI) is large, such as when detecting a vehicle or an obstacle in front of the traveling vehicle. There is a problem of overlooking.

 On the other hand, in the embodiment according to the present invention, as shown in FIG. 3, the solution is specified in consideration of the case of D ≦ I V I. In other words, since the solution is calculated for the region (1) and (3) of (D, V) shown in Fig. 5, it depends on the relationship between the distance (D) to the object and the relative velocity (IVI). It is possible to obtain an accurate distance and relative speed.

[0050] For example, when the original solution is the intersection (5), the intersection (5) is calculated as the solution. As a result, it is possible to prevent a distance that is longer than the original distance, smaller than the original relative speed, and erroneously recognized as a speed as in the past.

[0051] In the conventional method, if the slope k of the frequency change is increased, D increases and D <IVI can hardly occur. However, D and IVI cannot be completely eliminated, and the distribution range of beat frequencies is widened. (Because the maximum value of the beat frequency is the maximum value of D + IVI, it increases with the maximum value of D.) The load of frequency analysis processing such as FFT (the amount of calculation and the memory capacity used for calculation, etc.) There is a drawback that becomes larger. In this method, a correct solution can be obtained even if k is small, so that the beat frequency distribution range can be kept narrow, and the load of frequency analysis can be reduced.

 [0052] A specific calculation will be made assuming on-vehicle use. Assuming that fO is generally 75 GHz, the measurement distance range is 10 m—200 m, and the relative velocity range is −60 mZs— “h30 mZs (corresponding to 216 Km—“ l · 108 Km per hour). The relative speed was set to a large value considering the existence of oncoming vehicles.

 [0053] In order to be able to calculate correctly with the conventional method, the minimum value of D ≥ I V I maximum value is required.

 From equation (2)

 (2 * kZc) * (Minimum value of d) ≥ (2 * f0 / c) * (Maximum value of I V I)

 This power,

 k ≥ fO * (maximum value of I V I) / (minimum value of d)

 = 75GHz * (60m / s) / (10m)

 = 450GHz / s

 Maximum beat frequency bmax is

 bmax = maximum value of D + | maximum value of V |

 = (2 * kZc) * (maximum value of d)

 + (2 * f0 / c) * (maximum value of I V I)

 = (2 / c) * (450GHz / s * 200m + 75GHz * 60m / s)

 = 630KHz

It becomes. (Light speed c = 3 * 10 ⁸ mZs)

On the other hand, in the present invention, k may be a value of 0 or more in principle. However, if k is close to 0, the accuracy of the obtained distance will deteriorate, so it is sufficient to determine k carefully. [0054] Now, if the design is such that the maximum value of D is about the same as the maximum value of IVI, the accuracy of d and v is considered to be almost balanced. So the maximum value of D = | V |

 k = fo * (| maximum value of V |) / (maximum value of d) = 22.5 GHz / s

 See as. Then, the maximum value of the beat frequency is

 bmax = (2 * k / c) * (maximum value of d)

 + (2 * f0 / c) * (| V | maximum value)

 = (2 / c) * (22.5 GHz / s * 200m + 75GHz * 60m / s) = 60KHz

 Thus, it can be seen that it is less than one-tenth compared to the conventional method of 630 KHz.

[0055] If the beat frequency is high and distributed up to the frequency, it is obvious that the amount of calculation of the frequency analysis is increased accordingly. (As is well known, when the frequency is 10 times, 10 ² = 100 times in the discrete Fourier transform, and lOlog 10 = 33 times in the fast Fourier transform.

 2

 Add. )

 In the conventional method, the correct distance and relative velocity are not always obtained for the reflected wave of the object force at a distance of 0-10 m in the conventional method, but in the present invention, it is always obtained correctly in that region.

In the above description, the emission wave generated by the waveform pattern generation unit 10 is not limited to the waveform shown by the equations (5 a) to (5c). In other words, if there are three different frequency change patterns, and the slope of the frequency change at this time is kl, k2, and k3, the beat signal is

 bi = I (2 * kiZc) * d + (2 * fOZc) * v I

 = (2 * f0 / c) I (ki / fO) * d + v I

 And ai = kiZfO,

 bi = (2 * f0 / c) I ai * d + v I (10)

 It becomes. Where i = l, 2, 3

[0057] Here, if 1, a 2, a 3) = (k / fO, -k / fO, 0), it is possible to obtain equations (5a), (5b), and (5c). The

 In equation (10), for i = l, 2

bi = (2 * fOZc) i * d + v) bi = — (2 * fOZc) i * d + v)

 Solve for v

 v = ai * d + (cZ (2 * fO)) * bi

 v = ai * d— (cZ (2 * fO)) * bi

 It becomes. This is because two parallel lines are two sets, for a total of four linear forces,

 V = --a2 * d + (cZ (2 * fO)) * b2

 v = —al * d + (cZ (2 * fO)) * bl

 The intersection of

 v = --a2 * d + (cZ (2 * fO)) * b2

 v = al * d— (cZ (2 * fO)) * bl

 The intersection of

 v = a2 * d— (cZ (2 * fO)) * b2

 v = —al * d + (cZ (2 * fO)) * bl

 The intersection of

 v = a2 * d— (cZ (2 * fO)) * b2

 v = al * d— (cZ (2 * fO)) * bl

 4 points are required.

That is, when the candidate calculation unit 12 actually calculates these four intersections,

 dl = cZ (2 * fO (al—a2)) * (bl—b2)

 d2 = cZ (2 * fO (al— α2)) * (bl + b2)

 vl = c / (2 * f0 (al-a2)) * (b2 * al— bl * a 2)

 v2 = c / (2 * f0 (al-a2)) * (b2 * αΐ + bl * a 2)

 As

 (dl, vl), (d2, -v2), (— dl, — vl), (— d2, v2)

 The solution candidate can be calculated.

[0059] Further, when the specific processing unit 13 excludes d <0 solutions, the number of solutions is reduced to two. And the remaining 2 points and the following 2 straight lines

V = --a3 * d + (cZ (2 * fO)) * b3 v = a3 * d— (cZ (2 * fO)) * b3

 The solution can be specified if one point is determined according to the relationship.

[0060] For example, if the solution of d> 0 is (d, V) = (dl, vl), (d2, i2), the distance of the v component from the two straight lines is calculated as

 δ 11 = I vl + a3 * dl— (cZ (2 * fO)) * b3 I

 δ 12 = I vl + a3 * dl + (cZ (2 * fO)) * b3 I

 621 = I v2 + a3 * d2— (cZ (2 * fO)) * b3 I

 622 = I v2 + a3 * d2 + (cZ (2 * fO)) * b3 I

 If min (δ 11, δ 12) <min (δ 21, δ22), specify (dl, vl) as the solution, and min (δ 11, δ 12)> min (δ 21, δ 22) In this case, (d2, v2) can be specified as the solution. This process corresponds to the selection of 3 lines from 3 parallel lines, a total of 6 lines.

 [0061] In order to further improve the accuracy, the coordinates of the center of gravity of the triangle surrounded by the selected three straight lines may be solved.

 In equation (10), if the straight line when i = 1, the straight line when i = 2, and the straight line when i = 3 contain parallel lines, the intersection point will not be determined, so set the slopes different from each other. There is a need to. For example, you can determine ex i (ki) so that they intersect at an angle! ,.

 The present embodiment described above is also effective when there are reflected waves from a plurality of objects. The distance and relative speed calculation processing when there are reflected waves from a plurality of objects will be described below based on the flowchart shown in FIG.

 In the following, the frequency change pattern similar to the emission wave shown in FIG. 2 is generated and transmitted by the waveform pattern generation unit 10 as the simplest case of the frequency change pattern, and received by the reception unit 2 (receiving antenna 7 ) Explains the case of receiving two reflected waves, but this is not meant to be limiting.

[0064] In step S301, beat frequencies generated by mixing two reflected waves and emission waves received by the receiving antenna 7 by the mixing unit 8 are b 11 (when the frequency is increased), bl2 (when the frequency is increased), Assuming b21 (when the frequency is decreasing) and b22 (when the frequency is decreasing), the following eight lines are obtained. [0065] That is, the formula (5a) force is obtained.

 bll = D V. (11a)

 bll = — D- -v (lib)

 bl2 = D V (11c)

 bl2 = — D- -v ··· (lid)

 And formula (5b) force is obtained.

 b21 = D-V (lie)

 b21 = -D + V (llf)

 b22 = -D + V (llh)

 In total (8 straight lines (1 la)-(1 lh) shown in FIGS. 6A and 6B)). When the beat frequency is acquired, the control unit 3 shifts the processing to step S302, and the candidate calculation unit 12 performs calculation processing of the equation (11a)-(llh) force solution candidates. That is, the candidate calculation unit 12 calculates the intersection point of the straight line represented by the equations (11a)-(llh) at D> 0. In this embodiment, for example, as shown in FIG. 6A, eight intersections (10) to (17) are acquired. That is, eight (D, V) solution candidates are calculated.

[0066] Here, conventionally, only the region (1) shown in Fig. 5 is targeted, so only the four points of the intersections (10), (11), (14), and (15) are the candidate solutions. On the other hand, in the embodiment of the present invention, since the region (1) and (3) shown in FIG. 5 are targeted, eight points of intersections (10) to (17) are candidate solutions. It is possible to identify the optimal (correct) solution candidate.

 [0067] When the calculation of the solution candidate is completed by the process of step S302, the process proceeds to step S303, and the identification processing unit 13 performs the process of identifying the optimum solution for the solution candidate power calculated in step S302.

[0068] For example, assuming that the beat frequency of the non-modulation part (constant frequency part) acquired in step S301 is b31 and b32, V of intersection (10)-(17) calculated by the process of step S302 You can select two intersections whose values match each of b32 or b32, and specify these two points (D, V) as the solution. [0069] Actually, there is an error and it does not completely match. For example, the intersection where the distance (error) between the b b31 and the intersection (10)-(17) is the smallest, the b b and the intersection (10)-(17) It is only necessary to select the intersections that minimize the distance (error) and identify these two points (D, V) as the solution.

 [0070] Here, when specifying the intersection with the smallest distance as the solution, the absolute value of the intercept on the D-axis or V-axis of a total of four straight lines passing through the two selected points is bl l, By selecting the constraint condition that bl4, b21, and b22 must be covered as the condition for the specific processing of the solution in the specific processing unit 13, it is possible to prevent selecting an incorrect combination.

 [0071] For example, in FIG. 6A, the specific processing unit 13 calculates the errors between the operator b31 and the intersections (10) to (17), and selects the intersection (14) with the smallest error. At this time, the intersection (14) covers bl2 and b22, so the other intersection must cover bl l and b21. Therefore, the other intersection to be specified is only the intersection (11) or (12), and the intersection (12) having the smallest error with the b 32 is selected.

 [0072] In this example, the force that first determines the intersection point using the b b31 may first determine the intersection point using the b b32 and the remaining b b using the b b31. In order to further improve the accuracy, the solution with the smaller error of these two determination methods may be finally selected.

 [0073] In actual operation, the beat frequency may be degenerated. For example, b21 and b22 are detected as one beat frequency as a result of frequency analysis when the frequencies are close by chance. In some cases, the reflected wave is too weak to detect all three beat frequencies. Also, beat frequencies that are not possible due to external noise may be detected, but even in that case, it is possible to narrow down candidates by considering the possibility of degeneration and the possibility of noise using the strength of the beat signal. It is. Specifically, for example, the electric field strength is relatively strong, and the beat signal may be degenerated, so that the combination of distance and relative speed is tentatively obtained. The beat signal with low electric field strength is regarded as noise. It is only necessary to exhaustively try some cases, such as tentatively finding the combination of distance and relative speed after removal, and adopt the case with the smallest error when determining the combination of distance and relative speed. (In the case where all three beat signals are not captured, the beat signal detected for the object can be regarded as noise).

Claims

The scope of the claims  [1] Waveform pattern generation processing for generating a waveform pattern comprising three or more frequency change patterns;  A transmission process for generating a emission wave by frequency-modulating the waveform pattern generated by the waveform pattern generation process, and transmitting the emission wave;  A reception process for receiving the reflected wave reflected by the object from the emission wave;  A beat frequency acquisition process for acquiring the beat frequency corresponding to the pattern by mixing the emitted wave and the reflected wave;  The beat frequency is a relational power that the absolute value of the sum or difference between the first frequency component based on the time difference of the reflected wave and the second frequency component based on the Doppler effect is calculated. Distance and speed calculation processing,  A distance and speed measurement method using an FMCW radar. [2] The distance and speed calculation process includes:  When the slopes of the three frequency change patterns are kl, k2, and k3, the center frequency is fO, and the speed of light is c, the first beat frequency bl, the second beat frequency b2, and the third beat Relation between the frequency b3 and the first frequency component and the second frequency component bl = I (2 water kl / c) water d + (2 water fO / c) water VI  b2 = I (2 * k2Zc) * d + (2 * fOZc) * v I  b3 = I (2 water k3 / c) Water d + (2 water fO / c) Water v I  Specific processing to identify the distance d and relative velocity v of the object by solving  The distance and speed measurement method using the FMCW radar according to claim 1, comprising: [3] The waveform pattern generation process includes:  Generate a waveform pattern with three frequency change patterns: ascending, descending, and constant,  The calculation process is as follows: The first beat frequency is an absolute value of the sum of the first frequency component and the second frequency component, and the second beat frequency is the first frequency component and the second frequency component. The first frequency component and the second frequency component are identified based on the relationship that the third beat frequency is the absolute value of the second frequency component, 2. The distance and speed measuring method using the FMCW radar according to claim 1, further comprising a specific process for calculating a distance and a relative speed of the object. [4] The candidate calculation process includes a relational expression for the first beat frequency bl, the second beat frequency b2, the first frequency component D, and the second frequency component V.  bl = I D + V I  b2 = I D-V I  Solution candidate is calculated by solving  The specifying process is a relational expression for the third beat frequency b3.  b3 = I V I  4. The distance and speed measurement method using the FMCW radar according to claim 3, wherein a solution candidate having a minimum distance between the target and the solution candidate is identified as a distance and a relative speed of the target object. .  [5] When two reflected waves are received by the reception process,  In the identification process, the absolute value of the intercept on the D axis or the V axis of the straight line group that passes through the plurality of solution candidates to be identified on the DV plane is acquired by the beat frequency acquisition process. 3. The method for measuring distance and speed using the FMCW radar according to claim 2, wherein the frequency coverage is a constraint.  [6] A waveform pattern generation unit that generates a waveform pattern including three or more frequency change patterns;  A transmission unit for generating a emission wave by frequency-modulating the waveform pattern generated by the waveform pattern generation unit, and transmitting the emission wave;  A receiving unit for receiving a reflected wave reflected by an object from the emission wave;  A beat frequency acquisition unit that acquires the beat frequency corresponding to the pattern by mixing the emitted wave and the reflected wave; The relational power that the beat frequency is the absolute value of the sum or difference of the first frequency component based on the time difference of the reflected wave and the second frequency component based on the Doppler effect A distance and speed calculation unit for calculating the distance and relative speed of the object;  An apparatus for measuring distance and speed using an FMCW radar. [7] The distance and speed calculation unit includes:  When the slopes of the three frequency change patterns are kl, k2, and k3, the center frequency is fO, and the speed of light is c, the first beat frequency bl, the second beat frequency b2, and the third beat frequency b3 And the relationship between the first frequency component and the second frequency component bl = I (2 water kl / c) water d + (2 water fO / c) water VI  b2 = I (2 * k2Zc) * d + (2 * fOZc) * v I  b3 = I (2 water k3 / c) Water d + (2 water fO / c) Water v I  7. The distance and speed measuring device using the FMCW radar according to claim 6, further comprising: a specific processing unit that specifies a distance d and a relative speed v of the object by solving. [8] The waveform pattern generator  Generate a waveform pattern with three frequency change patterns: ascending, descending, and constant,  The calculation unit includes:  The first beat frequency is an absolute value of the sum of the first frequency component and the second frequency component, and the second beat frequency is the difference between the first frequency component and the second frequency component. The first frequency component and the second frequency component are identified based on a relationship that the absolute value of the difference and the third beat frequency is the absolute value of the second frequency component, and the target The distance and speed measuring device using the FMCW radar according to claim 6, further comprising a specific processing unit that calculates a distance and a relative speed of the object. [9] The candidate calculation unit includes a relational expression for the first beat frequency bl, the second beat frequency b2, the first frequency component D, and the second frequency component V.  bl = I D + V I  b2 = I D-V I  Solution candidate is calculated by solving The specific processing unit is a relational expression for the third beat frequency b3. b3 = I v I 9. The distance and speed measuring apparatus using the FMCW radar according to claim 8, wherein a solution candidate having a minimum distance between the target and the solution candidate is identified as a distance and a relative speed of the object. .  In the case where a plurality of reflected waves are received by the receiving unit,  The specific processing unit beats on the D-V plane, the beat value acquiring unit acquires the absolute value of the intercept on the D axis or the V axis of the straight line group that passes through the plurality of solution candidates specified as the solution. 10. The apparatus for measuring distance and speed using the FMCW radar according to claim 9, wherein the restriction is to cover frequencies.