Estimation method and estimation device

Abstract

Provided is an estimation method including: a reception step (S10) for receiving, with a first antenna and a second antenna, radio waves transmitted from a transmission antenna and including a reflected wave reflected by an object; a phase difference calculation step (S11) for calculating a phase difference between first reception radio waves, which are radio waves received by the first antenna in the reception step (S10), and second reception radio waves, which are radio waves received by the second antenna in the reception step (S10); a phase difference correction step (S12) for calculating a correction amount using the amplitude of the first reception radio waves and the amplitude of the second reception radio waves, and adding the calculated correction amount to the phase difference calculated in the phase difference calculation step (S11), thereby obtaining a corrected phase difference in which said phase difference is corrected; and an estimation step (S13) for estimating the direction in which the object is present on the basis of the corrected phase difference and the distance between the first antenna and the second antenna.

Description

[Technical Field]

[0001] The present disclosure relates to an estimation method and an estimation device. [Background technology]

[0002] Patent Document 1 discloses a technique that makes it possible to estimate the angle of arrival of received radio waves from the phase difference of the received radio waves. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2010-286402 Summary of the Invention [Problem to be solved by the invention]

[0004] However, with the technology disclosed in Patent Document 1, if the received radio waves are disturbed, for example, by including waves reflected by a reflecting object other than the target in addition to waves reflected by the target, the arrival angle of the received radio waves cannot be accurately estimated. In such cases, the direction to the target cannot be accurately estimated.

[0005] The present disclosure has been made in consideration of the above-mentioned circumstances, and aims to provide an estimation method and estimation device that can estimate the direction in which an object is located even if there is disturbance in the received radio waves. [Means for solving the problem]

[0006] In order to achieve the above object, an estimation method according to one embodiment of the present disclosure includes: a receiving step of receiving, by a first antenna and a second antenna different from the first antenna, radio waves transmitted from a transmitting antenna and including reflected waves reflected by an object; a phase difference calculation step of calculating a phase difference between a first received radio wave, which is the radio wave received by the first antenna in the receiving step, and a second received radio wave, which is the radio wave received by the second antenna in the receiving step; a phase difference correction step of calculating a correction amount using the amplitude of the first received radio wave and the amplitude of the second received radio wave, and adding the calculated correction amount to the phase difference calculated in the phase difference calculation step to obtain a corrected phase difference by correcting the phase difference; and an estimation step of estimating a direction in which the object is located based on the corrected phase difference and the distance between the first antenna and the second antenna.

[0007] In this way, by correcting the phase difference of the received radio waves with a correction amount that uses the amplitude of the received radio waves, it is possible to suppress disturbances in the phase difference of the received radio waves. Therefore, even if the received radio waves are disturbed, it is possible to estimate the angle of arrival of the received radio waves from the corrected phase difference, and therefore the direction in which the target is located can be estimated.

[0008] Here, for example, in the phase difference correcting step, the correction amount may be calculated using a coefficient and a value of the ratio between the amplitude of the first received radio wave and the amplitude of the second received radio wave.

[0009] In this way, by correcting the phase difference of the received radio waves with a correction amount that uses the value of the amplitude ratio of the received radio waves, it is possible to suppress disturbance in the phase difference of the received radio waves.

[0010] Here, for example, the absolute value of the correction amount becomes smaller as the value of the ratio approaches a predetermined value k, and the predetermined value k may be determined from experimental results or simulation results.

[0011] Furthermore, for example, in the phase difference correcting step, the correction amount may be calculated using a term having a highest degree of 2 or more, which is 2 or more and includes the ratio, and the coefficients 2 or more.

[0012] In this way, by correcting the phase difference of the received radio waves with a correction amount calculated using a high-order equation that uses the amplitude ratio of the received radio waves, it is possible to further suppress disturbance in the phase difference of the received radio waves.

[0013] Also, for example, in the phase difference correction step, a correction amount may be calculated using a difference between the amplitude of the first received radio wave and the amplitude of the second received radio wave and a coefficient, and the absolute value of the correction amount may be smaller as the absolute value of the difference is smaller.

[0014] In this way, by correcting the phase difference of the received radio waves with a correction amount that uses the amplitude difference of the received radio waves, it is possible to suppress disturbance in the phase difference of the received radio waves.

[0015] Furthermore, for example, in the phase difference correcting step, the correction amount may be calculated using two or more terms whose highest order is two or more and which include the difference, and the two or more coefficients.

[0016] In this way, by correcting the phase difference of the received radio waves with a correction amount calculated by a high-order equation using the amplitude difference of the received radio waves, it is possible to further suppress disturbance in the phase difference of the received radio waves.

[0017] Furthermore, for example, in the phase difference correcting step, the correction amount may be calculated using a coefficient and a value of the ratio of the sum and difference between the amplitude of the first received radio wave and the amplitude of the second received radio wave.

[0018] In this way, by correcting the phase difference of the received radio waves with a correction amount that uses the ratio between the sum and difference of the amplitudes of the received radio waves, it is possible to suppress disturbance in the phase difference of the received radio waves.

[0019] Here, for example, the absolute value of the correction amount may be smaller as the ratio of the difference to the sum approaches a predetermined value m.

[0020] Also, for example, in the phase difference correction step, the correction amount may be calculated using two or more terms whose highest order is two or more and which include the ratio of the sum and difference, and the two or more coefficients.

[0021] In this way, by correcting the phase difference of the received radio waves with a correction amount calculated using a high-order equation that uses the ratio of the sum and difference of the amplitudes of the received radio waves, it is possible to further suppress disturbances in the phase difference of the received radio waves.

[0022] Furthermore, for example, in the phase difference correction step, if the phase difference calculated in the phase difference calculation step is within a predetermined range including a range where monotonicity is lost in the relationship between the phase difference and the angle of arrival, the phase difference is corrected to obtain a corrected phase difference, and in the estimation step, if the phase difference is within the predetermined range, the direction may be estimated based on the corrected phase difference and the distance between the first antenna and the second antenna, and if the phase difference is not within the predetermined range, the direction may be estimated based on the phase difference and the distance between the first antenna and the second antenna.

[0023] As a result, in a phase difference range where the relationship between the phase difference and the angle of arrival is monotonic and there is no need to suppress disturbances in the phase difference of the received radio waves, the direction to the target can be estimated more accurately using the phase difference before correction.On the other hand, in a phase difference range where the relationship between the phase difference and the angle of arrival is disrupted by disturbances in the phase difference of the received radio waves, the direction to the target can be estimated more accurately using the phase difference after correction.

[0024] Here, for example, in the phase difference correction step, if the difference between the phase difference and the corrected phase difference at the boundary of the specified range is larger than a predetermined value, the corrected phase difference may be adjusted so that the difference between the phase difference and the corrected phase difference becomes smaller than the predetermined value.

[0025] This makes it possible to keep the gap between the post-correction phase difference value and the pre-correction phase difference value at the boundary between the characteristic curve using the pre-correction phase difference and the characteristic curve using the post-correction phase difference smaller than a predetermined value. As a result, the arrival angle of the received radio wave can be more accurately estimated from the post-correction phase difference or the pre-correction phase difference, and therefore the direction to the target object can be more accurately estimated.

[0026] Moreover, an estimation device according to one embodiment of the present disclosure includes: a receiving unit that receives radio waves transmitted from a transmitting antenna and including reflected waves reflected by an object at a first antenna and a second antenna different from the first antenna; a phase difference calculation unit that calculates a phase difference between a first received radio wave, which is the radio wave received by the first antenna in the receiving unit, and a second received radio wave, which is the radio wave received by the second antenna in the receiving unit; a phase difference correction unit that calculates a correction amount using the amplitude of the first received radio wave and the amplitude of the second received radio wave, and adds the calculated correction amount to the phase difference calculated by the phase difference calculation unit to obtain a corrected phase difference by correcting the phase difference; and an estimation unit that estimates a direction in which the object is located based on the corrected phase difference and the distance between the first antenna and the second antenna.

[0027] These comprehensive or specific aspects may be realized as a system, a method, an integrated circuit, a computer program, or a computer-readable recording medium such as a CD-ROM, or may be realized as any combination of a system, a method, an integrated circuit, a computer program, and a recording medium. [Effects of the Invention]

[0028] According to the estimation method and the like of the present disclosure, it is possible to estimate the direction in which an object exists even if there is disturbance in the received radio waves. [Brief explanation of the drawings]

[0029] [Figure 1] FIG. 1 is a diagram showing an example of a typical use scene of an estimation device according to an embodiment. [Figure 2] FIG. 2 is a diagram illustrating an example of a functional configuration of an estimation device according to an embodiment. [Figure 3] FIG. 3 is a diagram illustrating an example of a hardware configuration of a computer that realizes the functions of the estimation device according to the embodiment by software. [Figure 4A]FIG. 4A is a diagram for conceptually explaining a method for estimating an arrival angle according to a comparative example. [Figure 4B] FIG. 4B is a diagram for conceptually explaining a method for estimating an arrival angle according to a comparative example. [Figure 5A] FIG. 5A is a diagram for conceptually explaining a method for estimating an angle of arrival according to an embodiment. [Figure 5B] FIG. 5B is a diagram for conceptually explaining the method for estimating the angle of arrival according to the embodiment. [Figure 5C] FIG. 5C is a diagram for conceptually explaining a method for estimating an angle of arrival according to an embodiment. [Figure 6] FIG. 6 is a flowchart showing the operation of the estimation device according to the embodiment. [Figure 7A] FIG. 7A is a diagram for conceptually explaining the occurrence of a portion where the monotonicity of the characteristic curve of the corrected phase difference according to the modified example deteriorates. [Figure 7B] FIG. 7B is a diagram for conceptually explaining the occurrence of a portion where the monotonicity of the characteristic curve of the corrected phase difference according to the modified example deteriorates. [Figure 8A] FIG. 8A is a diagram conceptually illustrating that a gap occurring between the phase difference value before correction and the phase difference value after correction at a boundary portion according to a modified example can be adjusted by an offset. [Figure 8B] FIG. 8B is a diagram for conceptually explaining that a gap occurring between the phase difference value before correction and the phase difference value after correction at a boundary portion according to the modified example can be adjusted by an offset. DETAILED DESCRIPTION OF THE INVENTION

[0030] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. Note that each of the embodiments described below represents a specific example of the present disclosure. The numerical values, shapes, materials, components, component placement and connection configurations, usage procedures, communication procedures, etc. shown in the following embodiments are merely examples and are not intended to limit the present disclosure. Furthermore, among the components in the following embodiments, components that are not recited in the independent claims that represent the highest concept of the present disclosure will be described as optional components. Furthermore, each figure is not necessarily an exact illustration. In each figure, substantially identical components are assigned the same reference numerals, and redundant explanations are omitted or simplified.

[0031] (Embodiment) Hereinafter, an estimation device and an estimation method according to an embodiment will be described with reference to the drawings.

[0032] [1 Estimation device] FIG. 1 is a diagram showing an example of a typical use scene of an estimation device 10 according to an embodiment.

[0033] The estimation device 10 constitutes, for example, a radar and is used to estimate the direction of a target object 50. Typically, as shown in FIG. 1 , the estimation device 10 receives radio waves transmitted from a transmitting antenna 20 and including waves reflected by the target object 50, using a first antenna 31 and a second antenna 32. The estimation device 10 then estimates the angle of arrival of the radio waves including the waves reflected by the target object 50, using the phase difference between the radio waves received by the first antenna 31 and the radio waves received by the second antenna 32. Note that in this embodiment, for simplicity of explanation, the target object 50 will be described as moving in one direction.

[0034] FIG. 2 is a diagram illustrating an example of a functional configuration of the estimation device 10 according to the embodiment.

[0035] As shown in FIG. 2, the estimation device 10 includes a transmitting antenna 20, a first antenna 31, a second antenna 32, a transmitting unit 101, a receiving unit 102, a phase difference calculation unit 103, an amplitude calculation unit 104, a phase difference correction unit 105, and an arrival angle estimation unit 106.

[0036] 2 illustrates an example in which the estimation device 10 includes a first antenna 31 and a second antenna 32, but this is not limiting. The estimation device 10 may include more than two antennas. For example, if the estimation device 10 includes four antennas, it may operate using a pair of the first and second antennas, or a pair of the third and fourth antennas. Alternatively, if the estimation device 10 includes three antennas, it may operate using a pair of the first and second antennas, or a pair of the second and third antennas. Furthermore, the estimation device 10 does not necessarily include the transmitter 101 and the transmitting antenna 20. If the estimation device 10 does not include the transmitter 101 and the transmitting antenna 20, the transmitter 101 and the transmitting antenna 20 may be located near the estimation device 10.

[0037] Before describing each component of the estimation device 10, an example of the hardware configuration of the estimation device 10 according to this embodiment, excluding the transmitting antenna 20, the first antenna 31, and the second antenna 32, will be described below with reference to FIG. 3.

[0038] [1.1 Hardware configuration] FIG. 3 is a diagram illustrating an example of a hardware configuration of a computer 1000 that realizes the functions of the estimation device 10 according to the embodiment by software.

[0039] 3, the computer 1000 is a computer including an input device 1001, an output device 1002, a CPU 1003, an internal storage 1004, a RAM 1005, a reading device 1007, a transmitting / receiving device 1008, and a bus 1009. The input device 1001, the output device 1002, the CPU 1003, the internal storage 1004, the RAM 1005, the reading device 1007, and the transmitting / receiving device 1008 are connected by the bus 1009.

[0040] The input device 1001 is a user interface device such as an input button, a touchpad, a touch panel display, etc., and accepts user operations. Note that the input device 1001 may be configured to accept voice operations, remote operations using a remote control, etc., in addition to accepting user touch operations.

[0041] The output device 1002 is also used as the input device 1001, and is configured by a touch pad or a touch panel display, etc., and notifies the user of information that should be made known to the user.

[0042] The internal storage 1004 is a flash memory or the like. The internal storage 1004 may also store in advance at least one of a program for realizing the functions of the estimation device 10 and an application that utilizes the functional configuration of the estimation device 10.

[0043] The RAM 1005 is a random access memory, and is used to store data and the like when a program or application is executed.

[0044] The reading device 1007 reads information from a recording medium such as a USB (Universal Serial Bus) memory. The reading device 1007 reads the above-mentioned programs and applications from a recording medium on which the programs and applications are recorded, and stores the programs and applications in the built-in storage 1004.

[0045] The transmitting / receiving device 1008 is a communication circuit for performing wireless or wired communication. The transmitting / receiving device 1008 may communicate with, for example, a server device or a cloud connected to a network, download the above-mentioned programs and applications from the server device or the cloud, and store them in the built-in storage 1004.

[0046] The CPU 1003 is a central processing unit that copies programs and applications stored in the internal storage 1004 to the RAM 1005, and sequentially reads and executes instructions contained in the programs and applications from the RAM 1005.

[0047] Next, each functional configuration of the estimation device 10 according to this embodiment will be described.

[0048] [1.2 Transmitter 101] The transmitting unit 101 generates a high-frequency signal used to estimate the direction in which the target object 50 is located. The transmitting unit 101 includes a transmitting antenna 20 as shown in FIG. 2. In this embodiment, the transmitting unit 101 transmits the generated signal (radio wave) from the transmitting antenna 20.

[0049] 1.3 Receiving unit 102 The receiving unit 102 receives, at each of a plurality of antennas, radio waves that are transmitted from the transmitting antenna 20 and include waves reflected by the object 50. In this embodiment, the receiving unit 102 includes a first antenna 31 and a second antenna 32 that is different from the first antenna 31, as shown in FIG. 2. The receiving unit 102 receives, at the first antenna 31 and the second antenna 32, radio waves that are transmitted from the transmitting antenna 20 and include waves reflected by the object 50.

[0050] The receiving unit 102 outputs a first received radio wave, which is a radio wave received by the first antenna 31, and a second received radio wave, which is a radio wave received by the second antenna 32, to the phase difference calculation unit 103 and the amplitude calculation unit 104. In Fig. 2, the first received radio wave is denoted as RX1, and the second received radio wave is denoted as RX2.

[0051] If the receiving unit 102 has an even number of antennas, which is greater than two, the same can be said by designating each of the two antennas in a pair as the first antenna 31 and the second antenna 32.

[0052] [1.4 Phase difference calculation unit 103] The phase difference calculation unit 103 calculates the phase difference between the received radio waves from each of two antennas that form a pair in the plurality of antennas, from the radio waves received by the receiving unit 102. In this embodiment, the phase difference calculation unit 103 calculates the phase difference between the first received radio wave and the second received radio wave received by the receiving unit 102.

[0053] [1.5 Amplitude calculation unit 104] The amplitude calculation unit 104 calculates the amplitude of the radio waves received by the receiving unit 102. In this embodiment, the amplitude calculation unit 104 calculates the amplitude of the first received radio wave and the amplitude of the second received radio wave received by the receiving unit 102. Note that the amplitude calculation unit 104 may calculate the power of the radio waves received by the receiving unit 102 instead of the amplitude of the radio waves received by the receiving unit 102. Because the power includes information about the amplitude, it can be handled in the same way as the amplitude described below.

[0054] [1.6 Arrival angle estimation unit 106] The arrival angle estimation unit 106 estimates the direction in which the object 50 exists, based on the corrected phase difference calculated by the phase difference correction unit 105 and the distance between the first antenna 31 and the second antenna 32. In this embodiment, the arrival angle estimation unit 106 estimates the arrival angle of radio waves transmitted from the transmitting antenna 20 and including waves reflected by the object 50, based on the distance between the first antenna 31 and the second antenna 32 and the corrected phase difference. Here, the arrival angle of the radio waves is the angle of the radio waves arriving at the receiving unit 102, and in this embodiment, it is the angle of the radio waves arriving at the first antenna 31 and the second antenna 32. Then, the arrival angle estimation unit 106 can estimate the direction in which the object 50 exists, relative to the estimation device 10, by estimating the arrival angle of the radio waves arriving at the receiving unit 102.

[0055] 4A and 4B are diagrams for conceptually explaining a method for estimating an arrival angle according to a comparative example. Fig. 4A schematically shows how radio waves, including waves reflected by an object 50, arrive at the first antenna 31 and the second antenna 32 of the receiving unit 102 at an arrival angle α. Fig. 4B shows a curve 1 indicating the relationship between the phase difference and the arrival angle.

[0056] The arrival angle α shown in FIG. 4A can be expressed by the following equation (1): where λ is the wavelength of the radio wave and d is the distance (spacing) between the first antenna 31 and the second antenna 32.

[0057]

number

[0058] 4B shows a characteristic curve of the phase difference according to the comparative example, and corresponds to a graph of the above-mentioned (Equation 1). The measured value of the phase difference is the phase difference between RX1 and RX2 received by the receiving unit 102, and is calculated by the phase difference calculating unit 103.

[0059] As shown in FIG. 4B, if the phase difference between RX1 and RX2 received by the receiving unit 102 can be calculated, it is possible to uniquely estimate the angle of arrival.

[0060] 5A to 5C are diagrams for conceptually explaining a method for estimating an angle of arrival according to this embodiment.

[0061] 5A schematically shows how radio waves including waves reflected by an object 50 arrive at the first antenna 31 and the second antenna 32 of the receiving unit 102 at an arrival angle α. Compared to FIG. 4A, the radio waves including waves reflected by the object 50 also include waves reflected by a reflecting object 60 other than the object 50. Therefore, the radio waves received by the first antenna 31 and the second antenna 32 of the receiving unit 102 are disturbed.

[0062] Curve 2 shown in FIG. 5B indicates a characteristic curve of the phase difference according to this embodiment, and conceptually shows that there is a disturbance in the phase difference within a predetermined range.

[0063] In other words, when the receiving unit 102 receives radio waves that include waves reflected by the reflecting object 60 in addition to waves reflected by the object 50, the received radio waves are distorted due to the inclusion of unnecessary radio waves, and the characteristic curve of the phase difference is no longer monotonic, as shown by curve 2 in Fig. 5B. Note that, from curve 2 in Fig. 5B, the object 50 appears to be moving back and forth, even though it is actually moving in one direction.

[0064] Therefore, when the characteristic curve of the phase difference is not monotonic, as in curve 2 shown in FIG. 5B, even if the phase difference between RX1 and RX2 received by the receiving unit 102 is calculated, the angle of arrival cannot be uniquely estimated if curve 2 for the calculated phase difference is not monotonic.

[0065] Curve 3 shown in FIG. 5C is a characteristic curve of the corrected phase difference according to this embodiment, and when compared with curve 2, it conceptually shows that monotonicity is obtained.

[0066] As shown in curve 3 in FIG. 5C, by using a corrected phase difference obtained by correcting the phase difference calculated by the phase difference calculation unit 103 with the phase difference correction unit 105, it is possible to impart monotonicity to the relationship (characteristic curve of the phase difference indicating) between the corrected phase difference and the angle of arrival.

[0067] Therefore, since the characteristic curve of the corrected phase difference is monotonic, as shown by curve 3 in FIG. 5C, the arrival angle can be uniquely estimated by calculating the phase difference between RX1 and RX2 received by the receiving unit 102.

[0068] [1.7 Phase difference correction section 105] The inventors have discovered that the amplitudes of RX1 and RX2 often change with the same period as the disturbance in the phase difference between RX1 and RX2, and that the disturbance in the phase difference can be reduced by adding the amplitudes and an appropriate coefficient to the phase difference.

[0069] Furthermore, the inventors have discovered that by using the corrected phase difference obtained by correcting the phase difference in this manner, it is possible to impart monotonicity to the relationship between the corrected phase difference and the angle of arrival, and that by calculating the phase difference between RX1 and RX2, it is possible to uniquely estimate the angle of arrival.

[0070] Therefore, the phase difference correcting unit 105 corrects the phase difference calculated by the phase difference calculating unit 103 using the amplitude calculated by the amplitude calculating unit 104. In this embodiment, the phase difference correcting unit 105 calculates a correction amount using the amplitude of the first received radio wave and the amplitude of the second received radio wave, and adds the calculated correction amount to the phase difference calculated by the phase difference calculating unit 103 to obtain a corrected phase difference obtained by correcting the phase difference calculated by the phase difference calculating unit 103.

[0071] For example, the phase difference correction unit 105 may calculate the correction amount using a coefficient and a difference between the amplitude of the first received radio wave and the amplitude of the second received radio wave, and the absolute value of the correction amount should be smaller as the difference value is smaller. More specifically, the phase difference correction unit 105 corrects the phase difference θ calculated by the phase difference calculation unit 103 to obtain a corrected phase difference θ as shown in (Equation 2). comp In (Equation 2), c is a coefficient, a2 is the amplitude of the second received radio wave, and a1 is the amplitude of the first received radio wave.

[0072]

number

[0073] Furthermore, for example, the phase difference correction unit 105 may calculate the correction amount using a coefficient and a ratio between the amplitude of the first received radio wave and the amplitude of the second received radio wave. Because the amplitudes of the first received radio wave and the second received radio wave depend on the size and distance of the object 50, the influence of this can be eliminated by using the ratio between the amplitude of the first received radio wave and the amplitude of the second received radio wave. The absolute value of the correction amount should be smaller as the ratio value approaches a predetermined value k. More specifically, the phase difference correction unit 105 may obtain a corrected phase difference θcomp by correcting the phase difference θ calculated by the phase difference calculation unit 103, as shown in Equation 3. In Equation 3, c is a coefficient, a2 is the amplitude of the second received radio wave, and a1 is the amplitude of the first received radio wave. Furthermore, k may be set to an appropriate value based on actual measurements, simulation results, etc.

[0074]

number

[0075] Furthermore, for example, the phase difference correction unit 105 may calculate the correction amount using a coefficient and a value of the ratio of the sum and difference between the amplitude of the first received radio wave and the amplitude of the second received radio wave. This is because the amplitude of the first received radio wave and the amplitude of the second received radio wave depend on the size and distance of the object 50, and therefore the influence of this can be eliminated by using the ratio of the sum and difference between the amplitude of the first received radio wave and the amplitude of the second received radio wave. The absolute value of the correction amount should be smaller as the ratio of the difference to the sum approaches a predetermined value m. More specifically, the phase difference correction unit 105 calculates the corrected phase difference θ by correcting the phase difference θ calculated by the phase difference calculation unit 103, as shown in (Equation 4). comp In equation 4, c is a coefficient, a2 is the amplitude of the second received radio wave, and a1 is the amplitude of the first received radio wave. An appropriate value for m can be set based on actual measurements, simulation results, etc. If the numerator and denominator in the parentheses are divided by a1, it can be seen that, like equation 3, it depends on the ratio of the amplitude of the first received radio wave to the amplitude of the second received radio wave.

[0076]

number

[0077] The phase difference correcting unit 105 may use two or more coefficients (c1, c2, ...) to correct the phase difference calculated by the phase difference calculating unit 103 using a correction amount calculated by a higher-order equation. This is because a correction amount calculated by a higher-order equation can express a more flexible shape, and therefore can further reduce the disturbance of the phase difference calculated by the phase difference calculating unit 103.

[0078] Specifically, the phase difference correcting unit 105 corrects the phase difference θ calculated by the phase difference calculating unit 103 as shown in, for example, the following (Equation 5), (Equation 6), or (Equation 7), to obtain a corrected phase difference θ comp may be obtained.

[0079]

number

[0080]

number

[0081]

number

[0082] That is, the phase difference correction unit 105 may calculate the correction amount using two or more terms whose highest order is two or more and which include the difference in amplitude between the first received radio wave and the second received radio wave, and two or more coefficients, for example, as shown in (Equation 5).

[0083] Furthermore, the phase difference correction unit 105 may calculate the correction amount using a term having a highest order of 2 or more, which includes a ratio between the amplitude of the first received radio wave and the amplitude of the second received radio wave, and a coefficient of 2 or more, as shown in (Equation 6), for example.

[0084] Furthermore, the phase difference correction unit 105 may calculate the correction amount using two or more terms whose highest order is two or more and which include the ratio of the sum and difference between the amplitude of the first received radio wave and the amplitude of the second received radio wave, and two or more coefficients, for example, as shown in (Equation 7).

[0085] [2 Operation of the Estimation Device 10] Next, the operation of the estimation device 10 according to this embodiment will be described.

[0086] FIG. 6 is a flowchart showing the operation of the estimation device 10 according to the embodiment.

[0087] First, the estimation device 10 receives, via the first antenna 31 and the second antenna 32, radio waves transmitted from the transmitting antenna 20 and including waves reflected by the object 50 (S10).

[0088] Next, the estimation device 10 calculates the phase difference between the first received radio wave, which is the radio wave received by the first antenna 31 in step S10, and the second received radio wave, which is the radio wave received by the second antenna 32 in step S10 (S11).

[0089] Next, the estimation device 10 calculates a correction amount using the amplitude of the first received radio wave and the amplitude of the second received radio wave, and adds the calculated correction amount to the phase difference calculated in step S11 to obtain a corrected phase difference by correcting the phase difference (S12).

[0090] Next, the estimation device 10 estimates the direction in which the target object 50 exists based on the corrected phase difference obtained in step S10 and the distance between the first antenna and the second antenna (S13).

[0091] [3 Effects, etc.] As described above, the arrival angle of the object 50 can be calculated from the phase difference of the received radio waves when the radio waves, including the waves transmitted from the transmitting antenna 20 and reflected by the object 50, are received by multiple antennas. However, if the received radio waves contain waves reflected by an unintended reflecting object 60 and the phase difference is disturbed, the arrival angle of the object 50 cannot be calculated.

[0092] In response to this, the inventors discovered that the period of the phase difference disturbance of the received radio wave is synchronized with the amplitude period of the received radio wave. Furthermore, the inventors discovered that, although the phase difference characteristic curve does not return to a clean curve like when there is no phase difference disturbance, it is possible to impart monotonicity to the corrected phase difference characteristic curve obtained by adding a correction term to the phase difference equation that can suppress the phase difference disturbance using amplitude.

[0093] Therefore, in the estimation device 10 and estimation method according to the present embodiment, radio waves transmitted from a transmitting antenna and including waves reflected by an object are received by a first antenna and a second antenna, and a phase difference between a first received radio wave, which is the radio wave received by the first antenna, and a second received radio wave, which is the radio wave received by the second antenna, is calculated. Then, a correction amount is calculated using the amplitude of the first received radio wave and the amplitude of the second received radio wave, and added to the calculated phase difference to obtain a corrected phase difference by correcting the phase difference. The direction to the object is estimated based on the corrected phase difference and the distance between the first antenna and the second antenna.

[0094] In this way, the estimation device 10 and estimation method according to this embodiment correct the phase difference of the received radio waves with a correction amount that uses the amplitude of the received radio waves, thereby suppressing disturbances in the phase difference of the received radio waves, and therefore it is possible to estimate the angle of arrival of the received radio waves from the corrected phase difference even if the received radio waves are disturbed. Therefore, the estimation device 10 and estimation method according to this embodiment make it possible to estimate the direction in which the target object 50 is located.

[0095] Here, the phase difference of the received radio waves may be corrected using a correction amount that uses the value of the amplitude ratio of the received radio waves, or may be corrected using a correction amount that uses the value of the amplitude difference of the received radio waves, or may be corrected using a correction amount that uses the value of the ratio between the sum and difference of the amplitudes of the received radio waves. Whichever correction method is applied, it is possible to suppress disturbance in the phase difference of the received radio waves.

[0096] The correction amount may be calculated using a high-order equation that uses the amplitude ratio of the received radio waves, or may be calculated using a high-order equation that uses the amplitude difference of the received radio waves, or may be calculated using a high-order equation that uses the ratio of the sum and difference of the amplitudes of the received radio waves. By using any of these correction amounts, it is possible to further suppress the disturbance of the phase difference of the received radio waves.

[0097] (Variation) In the above embodiment, it has been explained that by correcting the phase difference by adding a correction term to the phase difference equation that can suppress disturbances in the phase difference using the amplitude of the received radio wave, it is possible to make the relationship between the corrected phase difference and the angle of arrival (i.e., the characteristic curve of the corrected phase difference) monotonic.

[0098] However, although the characteristic curve of the phase difference after correction can be made monotonic, there may be some portions where the monotonicity deteriorates compared to the relationship between the phase difference and the angle of arrival before correction (i.e., the characteristic curve of the phase difference before correction).

[0099] Therefore, in this modified example, we will explain the case where a characteristic curve of the corrected phase difference is used in which a correction term that can suppress phase difference disturbance using the amplitude of the received radio wave is added to the phase difference equation only in parts where monotonicity does not deteriorate compared to the characteristic curve of the pre-correction phase difference.

[0100] 7A and 7B are diagrams conceptually illustrating the occurrence of portions where the monotony deteriorates in the characteristic curve of the post-correction phase difference according to this modification. FIG. 7A is a diagram showing a characteristic curve of the pre-correction phase difference that exhibits disturbances in a predetermined range of the phase difference. Note that curve 2 shown in FIG. 7A is the same as curve 2 shown in FIG. 5B. Curve 4 shown in FIG. 7B is a characteristic curve of the post-correction phase difference in which the phase difference is corrected using a correction term that can suppress disturbances in the phase difference using the amplitude of the received radio wave, and FIG. 7B shows that portions where the monotony deteriorates occur in curve 4.

[0101] 7A and 7B, it can be seen that, in curve 4 of Fig. 7B, the disturbance in phase difference shown in curve 2 of Fig. 7A is suppressed and monotonicity is achieved, but the monotonicity is broken and deteriorated in region B compared to curve 2 of Fig. 7A. For this reason, it can be seen that the deterioration of monotonicity can be suppressed by making curve 4 only in the range Ax of arrival angles excluding region B and making curve 2 in the range outside range Ax.

[0102] Therefore, in this modification, the phase difference is corrected only within the range Ay of the phase difference before correction, which corresponds to the range Ax of the angle of arrival shown in Fig. 7A, thereby achieving better monotonicity over the entire range of the phase difference.

[0103] More specifically, when the phase difference calculated by the phase difference calculation unit 103 is within a predetermined range including a range in which the monotonicity is lost in the relationship between the phase difference and the angle of arrival, the phase difference correction unit 105 according to this modification obtains a corrected phase difference by correcting the phase difference.

[0104] Furthermore, when the phase difference calculated by the phase difference calculation unit 103 is within the predetermined range, the arrival angle estimation unit 106 according to this modification estimates the direction in which the object 50 exists based on the corrected phase difference obtained by the phase difference correction unit 105 and the distance between the first antenna and the second antenna. On the other hand, when the phase difference calculated by the phase difference calculation unit 103 is not within the predetermined range, the arrival angle estimation unit 106 according to this modification estimates the direction in which the object 50 exists based on the phase difference calculated by the phase difference calculation unit 103 and the distance between the first antenna 31 and the second antenna 32.

[0105] As a result, in a phase difference range where the relationship between the phase difference and the angle of arrival (characteristic curve of the phase difference before correction) is monotonic and there is no need to suppress disturbances in the phase difference of the received radio waves, the direction to the location of the target can be estimated with greater accuracy using the phase difference before correction.On the other hand, in a phase difference range where the monotonicity is lost due to disturbances in the phase difference of the received radio waves in the relationship between the phase difference and the angle of arrival (characteristic curve of the phase difference before correction), the direction to the location of the target can be estimated with greater accuracy using the phase difference after correction.

[0106] 7A, a gap (step or deviation) may occur between the pre-correction phase difference value and the post-correction phase difference value at the boundary of the pre-correction phase difference range Ay in range C. In such a case, the offset or slope of at least one of the pre-correction phase difference and the post-correction phase difference may be adjusted to reduce the gap to an allowable value or less.

[0107] 8A and 8B are diagrams for conceptually explaining that a gap occurring between the phase difference value before correction and the phase difference value after correction at a boundary portion according to this modification can be adjusted by an offset.

[0108] Fig. 8A shows that a gap (step, deviation) occurs between curve 4 shown in Fig. 7B and curve 2 shown in Fig. 7A at the boundary portion in range C shown in Fig. 7A. Fig. 8A also shows an example in which the gap between curve 4 shown in Fig. 7B and curve 2 shown in Fig. 7A is eliminated by adjusting the offset of curve 4 shown in Fig. 7B, i.e., the phase difference after correction, to obtain curve 5. Fig. 8B shows that there is no gap at the boundary portion between curve 2, which represents the characteristic curve of the phase difference before correction, and curve 5, which represents the characteristic curve of the phase difference after correction with the offset adjusted.

[0109] In this way, by adjusting the offset of the phase difference after correction, the gap that occurs between the phase difference value before correction and the phase difference value after correction at the boundary part in range C can be made to be equal to or less than an acceptable value (a predetermined value), such as 0.

[0110] More specifically, the phase difference correction unit 105 according to this modification may further adjust the corrected phase difference so that the difference between the phase difference and the corrected phase difference becomes smaller than the predetermined value when the difference between the phase difference and the corrected phase difference is larger than a predetermined value at the boundary of a predetermined range.

[0111] This makes it possible to keep the gap between the post-correction phase difference value and the pre-correction phase difference value at the boundary between the characteristic curve using the pre-correction phase difference and the characteristic curve using the post-correction phase difference smaller than a predetermined value. As a result, the arrival angle of the received radio wave can be more accurately estimated from the post-correction phase difference or the pre-correction phase difference, and therefore the direction to the target object can be more accurately estimated.

[0112] While the estimation method and estimation device according to aspects of the present disclosure have been described above based on embodiments, the present disclosure is not limited to these embodiments. For example, the present disclosure may be embodied in another embodiment realized by arbitrarily combining the components described in this specification or excluding some of the components. Furthermore, the present disclosure also includes various modifications that would be conceivable by a person skilled in the art to the above-described embodiments without departing from the spirit of the present disclosure, i.e., the meaning of the wording set forth in the claims.

[0113] The following aspects may also be included within the scope of one or more aspects of the present disclosure.

[0114] (1) Some of the components constituting the above-described estimation device may be a computer system composed of a microprocessor, ROM, RAM, hard disk unit, display unit, keyboard, mouse, etc. A computer program is stored in the RAM or hard disk unit. The microprocessor operates in accordance with the computer program to achieve its functions. Here, the computer program is composed of a combination of multiple instruction codes that indicate instructions to a computer to achieve a predetermined function.

[0115] (2) Some of the components constituting the above-described estimation device may be configured as a single system LSI (Large Scale Integration). The system LSI is an ultra-multifunctional LSI manufactured by integrating multiple components on a single chip, and specifically, is a computer system configured to include a microprocessor, ROM, RAM, etc. A computer program is stored in the RAM. The system LSI achieves its functions when the microprocessor operates in accordance with the computer program.

[0116] (3) Some of the components constituting the above-mentioned estimation device may be composed of an IC card or a standalone module that can be attached to each device. The IC card or the module is a computer system composed of a microprocessor, ROM, RAM, etc. The IC card or the module may include the above-mentioned ultra-multifunctional LSI. The IC card or the module achieves its functions when the microprocessor operates according to a computer program. The IC card or the module may be tamper-resistant.

[0117] (4) Furthermore, some of the components constituting the above-described estimation device may be the computer program or digital signal recorded on a computer-readable recording medium, such as a flexible disk, hard disk, CD-ROM, MO, DVD, DVD-ROM, DVD-RAM, BD (Blu-ray (registered trademark) Disc), semiconductor memory, etc. Alternatively, the components may be the digital signal recorded on such a recording medium.

[0118] In addition, some of the components constituting the above AP may transmit the computer program or the digital signal via a telecommunications line, a wireless or wired communication line, a network such as the Internet, data broadcasting, etc.

[0119] (5) The present disclosure may be embodied as the methods described above, a computer program for implementing these methods on a computer, or a digital signal comprising the computer program.

[0120] (6) The present disclosure may also be a computer system having a microprocessor and a memory, the memory storing the computer program, and the microprocessor operating in accordance with the computer program.

[0121] (7) The program or the digital signal may also be implemented by another independent computer system by recording it on the recording medium and transferring it, or by transferring the program or the digital signal via the network, etc.

[0122] (8) The above-described embodiments and modifications may be combined with each other. [Industrial Applicability]

[0123] The present disclosure can be used in estimation methods and estimation devices, and in particular in estimation methods and estimation devices for use in radar and the like to estimate the direction in which a target object exists. [Explanation of symbols]

[0124] 10 Estimation device 20 transmitting antennas 31 First Antenna 32 Second Antenna 50 Objects 60 Reflective objects 101 Transmitter 102 Receiving unit 103 Phase difference calculation section 104 Amplitude calculation unit 105 Phase difference correction section 106 Arrival angle estimator

Claims

1. A receiving step of receiving radio waves transmitted from a transmitting antenna and including reflected waves reflected by an object by a first antenna and a second antenna different from the first antenna; a phase difference calculation step of calculating a phase difference between a first received radio wave, which is a radio wave received by the first antenna in the receiving step, and a second received radio wave, which is a radio wave received by the second antenna in the receiving step; a phase difference correcting step of calculating a correction amount using the amplitude of the first received radio wave and the amplitude of the second received radio wave, and adding the calculated correction amount to the phase difference calculated in the phase difference calculating step to obtain a corrected phase difference by correcting the phase difference; an estimation step of estimating a direction in which the object is present based on the corrected phase difference and a distance between the first antenna and the second antenna, the phase difference correcting step calculates a correction amount using a ratio between the amplitude of the first received radio wave and the amplitude of the second received radio wave and a coefficient by which the ratio is multiplied; Estimation method.

2. The absolute value of the correction amount becomes smaller as the value of the ratio approaches a predetermined value k, The predetermined value k is determined based on experimental results or simulation results. The estimation method according to claim 1 .

3. In the phase difference correction step, calculating a correction amount using two or more terms having a highest degree of two or more and including the ratio, and the two or more coefficients; The estimation method according to claim 2 .

4. A receiving step of receiving radio waves transmitted from a transmitting antenna and including reflected waves reflected by an object by a first antenna and a second antenna different from the first antenna; a phase difference calculation step of calculating a phase difference between a first received radio wave, which is a radio wave received by the first antenna in the receiving step, and a second received radio wave, which is a radio wave received by the second antenna in the receiving step; a phase difference correcting step of calculating a correction amount using the amplitude of the first received radio wave and the amplitude of the second received radio wave, and adding the calculated correction amount to the phase difference calculated in the phase difference calculating step to obtain a corrected phase difference by correcting the phase difference; an estimation step of estimating a direction in which the object is present based on the corrected phase difference and a distance between the first antenna and the second antenna, the phase difference correcting step calculates a correction amount using a difference between the amplitude of the first received radio wave and the amplitude of the second received radio wave and a coefficient by which the difference is multiplied; The absolute value of the correction amount is smaller as the absolute value of the difference is smaller. Estimation method.

5. In the phase difference correction step, calculating a correction amount using two or more terms having a highest degree of two or more and including the difference, and the two or more coefficients; The estimation method according to claim 4.

6. A receiving step of receiving radio waves transmitted from a transmitting antenna and including reflected waves reflected by an object by a first antenna and a second antenna different from the first antenna; a phase difference calculation step of calculating a phase difference between a first received radio wave, which is a radio wave received by the first antenna in the receiving step, and a second received radio wave, which is a radio wave received by the second antenna in the receiving step; a phase difference correcting step of calculating a correction amount using the amplitude of the first received radio wave and the amplitude of the second received radio wave, and adding the calculated correction amount to the phase difference calculated in the phase difference calculating step to obtain a corrected phase difference by correcting the phase difference; an estimation step of estimating a direction in which the object is present based on the corrected phase difference and a distance between the first antenna and the second antenna, the phase difference correcting step calculates a correction amount using a ratio of a sum and a difference between the amplitude of the first received radio wave and the amplitude of the second received radio wave, and a coefficient by which the ratio of the sum and the difference is multiplied; Estimation method.

7. The absolute value of the correction amount becomes smaller as the ratio of the difference to the sum approaches a predetermined value m. The estimation method according to claim 6.

8. In the phase difference correction step, calculating a correction amount using two or more terms having a highest degree of two or more and including the ratio of the sum and the difference, and the two or more coefficients; The estimation method according to claim 6 or 7.

9. A receiving step of receiving radio waves transmitted from a transmitting antenna and including reflected waves reflected by an object by a first antenna and a second antenna different from the first antenna; a phase difference calculation step of calculating a phase difference between a first received radio wave, which is a radio wave received by the first antenna in the receiving step, and a second received radio wave, which is a radio wave received by the second antenna in the receiving step; a phase difference correcting step of calculating a correction amount using the amplitude of the first received radio wave and the amplitude of the second received radio wave, and adding the calculated correction amount to the phase difference calculated in the phase difference calculating step to obtain a corrected phase difference by correcting the phase difference; an estimation step of estimating a direction in which the object is present based on the corrected phase difference and a distance between the first antenna and the second antenna, In the phase difference correction step, If the phase difference calculated in the phase difference calculation step is within a range in which monotonicity is lost in the relationship between the phase difference and the arrival angle, a corrected phase difference is obtained by correcting the phase difference; In the estimation step, If the phase difference is within the range, estimating the direction based on the corrected phase difference and the distance between the first antenna and the second antenna; If the phase difference is not within the range, estimating the direction based on the phase difference and the distance between the first antenna and the second antenna. Estimation method.

10. In the phase difference correcting step, when a difference between the phase difference and the corrected phase difference at the boundary of the range is larger than a predetermined value, the corrected phase difference is adjusted so that the difference between the phase difference and the corrected phase difference becomes smaller than the predetermined value. The estimation method according to claim 9.

11. a receiving unit that receives radio waves transmitted from a transmitting antenna and including reflected waves reflected by an object, using a first antenna and a second antenna different from the first antenna; a phase difference calculation unit that calculates a phase difference between a first received radio wave that is a radio wave received by the first antenna in the receiving unit and a second received radio wave that is a radio wave received by the second antenna in the receiving unit; a phase difference correction unit that calculates a correction amount using the amplitude of the first received radio wave and the amplitude of the second received radio wave, and adds the calculated correction amount to the phase difference calculated by the phase difference calculation unit to obtain a corrected phase difference by correcting the phase difference; an estimation unit that estimates a direction in which the object is present based on the corrected phase difference and a distance between the first antenna and the second antenna, the phase difference correction unit calculates a correction amount using a ratio between the amplitude of the first received radio wave and the amplitude of the second received radio wave and a coefficient by which the ratio is multiplied; Estimation device.

12. a receiving unit that receives radio waves transmitted from a transmitting antenna and including reflected waves reflected by an object, using a first antenna and a second antenna different from the first antenna; a phase difference calculation unit that calculates a phase difference between a first received radio wave that is a radio wave received by the first antenna in the receiving unit and a second received radio wave that is a radio wave received by the second antenna in the receiving unit; a phase difference correction unit that calculates a correction amount using the amplitude of the first received radio wave and the amplitude of the second received radio wave, and adds the calculated correction amount to the phase difference calculated by the phase difference calculation unit to obtain a corrected phase difference by correcting the phase difference; an estimation unit that estimates a direction in which the object is present based on the corrected phase difference and a distance between the first antenna and the second antenna, the phase difference correction unit calculates a correction amount using a difference between the amplitude of the first received radio wave and the amplitude of the second received radio wave and a coefficient by which the difference is multiplied; The absolute value of the correction amount is smaller as the absolute value of the difference is smaller. Estimation device.

13. a receiving unit that receives radio waves transmitted from a transmitting antenna and including reflected waves reflected by an object, using a first antenna and a second antenna different from the first antenna; a phase difference calculation unit that calculates a phase difference between a first received radio wave that is a radio wave received by the first antenna in the receiving unit and a second received radio wave that is a radio wave received by the second antenna in the receiving unit; a phase difference correction unit that calculates a correction amount using the amplitude of the first received radio wave and the amplitude of the second received radio wave, and adds the calculated correction amount to the phase difference calculated by the phase difference calculation unit to obtain a corrected phase difference by correcting the phase difference; an estimation unit that estimates a direction in which the object is present based on the corrected phase difference and a distance between the first antenna and the second antenna, the phase difference correction unit calculates a correction amount using a value of a ratio of a sum and a difference between an amplitude of the first received radio wave and an amplitude of the second received radio wave, and a coefficient by which the value of the ratio of the sum and the difference is multiplied; Estimation device.

14. a receiving unit that receives radio waves transmitted from a transmitting antenna and including reflected waves reflected by an object, using a first antenna and a second antenna different from the first antenna; a phase difference calculation unit that calculates a phase difference between a first received radio wave that is a radio wave received by the first antenna in the receiving unit and a second received radio wave that is a radio wave received by the second antenna in the receiving unit; a phase difference correction unit that calculates a correction amount using the amplitude of the first received radio wave and the amplitude of the second received radio wave, and adds the calculated correction amount to the phase difference calculated by the phase difference calculation unit to obtain a corrected phase difference by correcting the phase difference; an estimation unit that estimates a direction in which the object is present based on the corrected phase difference and a distance between the first antenna and the second antenna, The phase difference correction unit If the phase difference calculated by the phase difference calculation unit is within a range in which monotonicity is lost in the relationship between the phase difference and the arrival angle, a corrected phase difference is obtained by correcting the phase difference; The estimation unit If the phase difference is within the range, estimating the direction based on the corrected phase difference and the distance between the first antenna and the second antenna; If the phase difference is not within the range, estimating the direction based on the phase difference and the distance between the first antenna and the second antenna. Estimation device.

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