Information processing method, information processing device, and information processing program

Abstract

To provide an information processing method capable of accurately and stably identifying a vehicle speed, an information processing device, and an information processing program.SOLUTION: An information processing method causes a computer to perform processing for: acquiring the Doppler velocities of a plurality of targets and azimuths of the targets based on a mobile body by a Doppler radar mounted on the mobile body; when the speed, acceleration, and yaw rate of the mobile body meet prescribed conditions, generating a regression curve indicative of the relationship between the Doppler velocities and the azimuths on the basis of the orthogonal distance from the acquired Doppler velocities and the azimuths to the regression curve; and identifying the speed of the mobile body on the basis of the generated regression curve.SELECTED DRAWING: Figure 7

Description

[Technical field]

[0001] The present invention relates to an information processing method, an information processing device, and an information processing program for identifying the speed of a moving object. [Background technology]

[0002] In passenger cars, trucks, and other vehicles that perform autonomous driving or driving assistance, sensors such as radar perform self-diagnosis of their mounting angles and self-calibration of measured angles, and precise measurement of the vehicle's speed is essential for these processes.In addition, precise vehicle speed is also essential for improving tracking accuracy in tracking processes that continuously identify the positions of surrounding vehicles and pedestrians.

[0003] Thus, precise vehicle speed is important measurement data for controlling a vehicle. However, it is known that vehicle speed sensors used up to now have errors due to the structure of the vehicle. Vehicle speed sensors generally determine vehicle speed in the following procedure. The rotation of the tire is measured with a rotary encoder, and the rotation speed of the axle is determined from the number of pulses per time output by the rotary encoder. The vehicle speed is calculated from the rotation speed of the axle and the tire circumference. Therefore, if the tire circumference changes due to insufficient air pressure or wear in the tire, an error will occur between the actual vehicle speed and the calculated vehicle speed.

[0004] In such a situation, a Doppler radar installed on a vehicle is used to detect the vehicle speed. A Doppler radar emits radio waves in the microwave or millimeter wave band. The emitted radio waves are called the transmitted waves. The transmitted waves are reflected by objects around the vehicle and return. The returning radio waves are called the reflected waves. An object that reflects the transmitted waves and is detected by the Doppler radar is called a target. If there is a speed difference between the target and the Doppler radar, the reflected wave has a frequency shift due to the Doppler effect. This shift is called a Doppler shift. It is possible to calculate the relative speed with respect to the target based on the amount of Doppler shift and the angle (called the "azimuth") that indicates the direction in which the reflected wave returns. If the target is a stationary object on the road, a traffic light, a road sign, a road lamp, or a roadside tree, the calculated relative speed will be equal to the vehicle speed.

[0005] However, since the vehicle is moving between when the Doppler radar emits the transmitted wave and when it measures the reflected wave, even if the target is a stationary object, a measurement error occurs in the azimuth angle, which results in an error in the vehicle speed. Patent Document 1 proposes a detection device that uses only reflected waves whose azimuth angles are smaller than a predetermined threshold value to improve the accuracy of the calculated vehicle speed, since the smaller the azimuth angle value, the smaller the error. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] JP 2019-7926 A Summary of the Invention [Problem to be solved by the invention]

[0007] However, in the conventional technology, only targets that return reflected waves with azimuth angles smaller than a predetermined threshold are used, so it may be difficult to stably detect the vehicle speed. The present invention has been made in consideration of such circumstances. An object of the present invention is to provide an information processing method, an information processing device, and an information processing program that are capable of accurately and stably specifying the vehicle speed. [Means for solving the problem]

[0008] An information processing method according to one aspect of the present application includes a computer that acquires Doppler velocities of a plurality of targets and azimuth angles of the targets relative to the moving body from a Doppler radar mounted on a moving body, and when the speed, acceleration, and yaw rate of the moving body satisfy predetermined conditions, generates a regression curve showing the relationship between the Doppler speed and the azimuth angle based on the orthogonal distance from the acquired Doppler speed and azimuth angle to the regression curve, and determines the speed of the moving body based on the generated regression curve. Effect of the Invention

[0009] According to one aspect of the present application, the vehicle speed can be determined accurately and stably. [Brief description of the drawings]

[0010] [Figure 1] FIG. 1 is an explanatory diagram illustrating an example of the configuration of an information system. [Diagram 2] FIG. 2 is a block diagram showing an example of the configuration of an ECU and a Doppler radar. [Diagram 3] FIG. 1 is an explanatory diagram showing the measurement principle of a Doppler radar. [Figure 4] 1 is a graph showing an example of a Doppler radar measurement result and a fitting curve. [Diagram 5] FIG. 11 is an explanatory diagram regarding a fitting method. [Figure 6] FIG. 4 is an explanatory diagram showing an example of a target list. [Figure 7] 10 is a flowchart illustrating an example of a procedure for a measurement process. [Figure 8] 13 is a graph showing an example of an estimation result. [Figure 9] 10 is a flowchart illustrating another example of a procedure of the measurement process. [Figure 10] 13 is a flowchart illustrating an example of a procedure for a filtering process. [Figure 11] 13 is a flowchart illustrating another example of a procedure for the filtering process. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Hereinafter, an embodiment will be described with reference to the drawings. FIG. 1 is an explanatory diagram showing an example of the configuration of an information system. The information system includes an ECU (Electronic Control Unit) 1, a Doppler radar 2, and a vehicle 3. FIG. 1 is a diagram showing the vehicle 3 traveling on a road as viewed from above. The ECU 1 and the Doppler radar 2 are mounted on the vehicle 3. For example, the ECU 1 is installed inside the vehicle cabin. The Doppler radar 2 is installed inside a bumper, an emblem, or the like so that it is not visible from the outside. The ECU 1 is an example of an information processing device. The vehicle 3 is an example of a moving body. Also, a part of the information processing may be performed in the Doppler radar, and the remaining information processing may be performed by the ECU 1. The ECU 1 may be configured to be provided inside the Doppler radar 2.

[0012] The target 4 is an object that exists on the road or in the vicinity of the road. The target includes moving objects such as traffic participants such as cars and people, obstacles, walls, and objects that are stationary on the ground such as telephone poles. The target also includes structures such as road shoulders and sidewalk steps. Moving targets, including those that are temporarily stopped, are called dynamic targets, and stationary targets are called static targets.

[0013] 2 is a block diagram showing an example of the configuration of the ECU and the Doppler radar. The ECU 1 includes a control unit 11, a storage unit 12, a communication unit 13, and an interface 14. The control unit 11 is configured with a CPU (Central Processing Unit) or an MPU (Micro Processing Unit), etc. The control unit 11 performs various control processes and arithmetic processes by reading and executing a control program 1P and data stored in advance in the storage unit 12. The control unit 11 functions as an acquisition unit, a generation unit, and an identification unit by executing the control program 1P (program product) stored in the storage unit 12.

[0014] The storage unit 12 is configured with memory elements such as RAM (Random Access Memory) or ROM (Read Only Memory), such as DRAM (Dynamic RAM), EEPROM (Electrically Erasable Programmable ROM) or flash memory. The storage unit 12 stores in advance a control program and data to be referenced during processing. The control program stored in the storage unit 12 may be a control program 1P read from a recording medium 1a readable by the EUC 1. Alternatively, the control program 1P may be downloaded from an external computer (not shown) connected to a communication network (not shown) and stored in the storage unit 12.

[0015] The communication unit 13 is a communication interface using a communication protocol such as CAN (Control Area Network), LIN (Local Interconnect Network), Ethernet (registered trademark), etc. The communication unit 13 communicates with in-vehicle devices connected to the in-vehicle network.

[0016] The interface 14 is an interface for performing serial communication or parallel communication. The interface 14 and the Doppler radar 2 are connected by a cable or the like. The interface 14 is an interface for inputting and outputting data between the control unit 11 and the Doppler radar 2.

[0017] The Doppler radar 2 includes a transmitter 21, a transmitting antenna 22, a receiver 23, and a receiving antenna 24. The transmitter 21 is connected to the ECU 1 via an interface 14. The transmitter 21 transmits radio waves (transmission waves) based on a signal from the control unit 11 of the ECU 1. The transmission waves are, for example, radio waves in the millimeter wave band from 30 GHz to 300 GHz, or in the microwave band from 300 MHz to 300 GHz.

[0018] The transmitting antenna 22 is a directional antenna that transmits radio waves with different strengths depending on the direction. The transmitting antenna 22 is connected to the transmitting unit 21, and transmits radio waves (transmission waves) by output from the transmitting unit 21.

[0019] The receiving antenna 24 is a directional antenna whose receiving sensitivity varies depending on the direction. The receiving antenna 24 is connected to the receiving unit 23 and is arranged so as to face substantially the same direction as the transmitting antenna 22. The receiving antenna 24 receives waves reflected by a target and outputs them to the receiving unit 23. The range in which the Doppler radar 2 detects a target is determined by the directivity of the transmitting antenna 22 and the directivity of the receiving antenna 24.

[0020] The receiving unit 23 is connected to the ECU 1 via the interface 14. The receiving unit 23 acquires a reflected wave reflected by the target 4 via a receiving antenna 24. The receiving unit 23 performs, for example, A / D conversion on the acquired reflected wave and outputs it to the control unit 11.

[0021] Fig. 3 is an explanatory diagram showing the measurement principle of Doppler radar. A transmission wave is emitted by a transmitter 21 of the Doppler radar 2 via a transmission antenna 22. The transmission wave is reflected by a target in the vicinity of the vehicle. The reflected wave is observed by a receiver 23 via a receiving antenna 24. The difference in frequency between the transmission wave and the reflected wave is a frequency that corresponds to the relative speed between the target and the Doppler radar 2. This frequency is called the Doppler frequency. From the Doppler frequency, it is possible to calculate the relative speed (Doppler speed) of the target with respect to the Doppler radar 2 attached to the vehicle 3.

[0022] The receiving antenna 24 of the Doppler radar 2 is composed of multiple small antennas with directivity, and the azimuth angle of the reflected wave is calculated from the phase difference of the reflected wave received by each small antenna. The azimuth angle between the target and the Doppler radar 2 is derived based on the forward traveling direction of the traveling vehicle 3 (front direction of the vehicle). Therefore, if the speed of the vehicle 3 is Host V and the azimuth angle of the target is θ, the relative speed (Doppler speed) of the target is V d is expressed by the following equation (1).

[0023] V d = -1 * Host V * cosθ … (1)

[0024] When θ is 0, cosθ=1, and V d = -1 * Host V. That is, the Doppler velocity V d The extreme value (maximum absolute value) of is equal to the vehicle speed Host V. Doppler velocity V d If the vehicle speed Host V can be measured with high accuracy, the Host V can be calculated with high accuracy.

[0025] However, measurements using the Doppler radar 2 are subject to the following error factors. These are installation errors that occur when the transmitting antenna 22 and the receiving antenna 24 of the Doppler radar 2 are attached to the vehicle 3. Even a slight installation error will cause an error in the azimuth angle θ. Furthermore, in order not to spoil the external design of the vehicle 3, the transmitting antenna 22 and the receiving antenna 24 are usually housed in a housing and covered with a cover called a radome before being attached to the vehicle 3. When the reflected wave passes through the radome, slight refraction occurs, which will cause an error in the azimuth angle θ.

[0026] Doppler velocity V d In order to obtain the vehicle speed Host V with higher accuracy, the error is corrected. As described above, the azimuth angle θ is the explanatory variable, and the objective variable is the Doppler velocity V d The function is a trigonometric function. In addition, when there are multiple targets around the vehicle 3 and reflected waves from multiple targets are observed in one measurement, the vehicle speed Host V can be considered to be constant. Therefore, multiple observation data by the Doppler radar 2 are calculated by using the azimuth angle θ as an explanatory variable and the Doppler speed V as a target variable. d By fitting to a trigonometric function (cosine function) such that:

[0027] FIG. 4 is a graph showing an example of Doppler radar measurement results and fitting curves. The horizontal axis is azimuth angle θ, with units in radians, for example. The vertical axis is Doppler velocity, with units in meters per second (m / s) or kilometers per hour (km / h), for example. If the vehicle speed value is positive, the Doppler velocity will be a negative value, but in FIG. 4 it is shown as an absolute value. The points shown in FIG. 4 show the observation results of multiple targets by the Doppler radar 2. The points showing the observation results will hereinafter be referred to as observation points. The curve is a fitting curve (regression curve) obtained by fitting the observation results.

[0028] FIG. 5 is an explanatory diagram of the fitting method. FIG. 5A is an explanatory diagram of fitting by the least squares method. FIG. 5B is an explanatory diagram of fitting by orthogonal distance regression. First, consider FIG. 5A. As shown in FIG. 5A, in the least squares method, the difference between the observation point and the fitting curve is evaluated in the vertical axis direction. Therefore, as shown in the left diagram of FIG. 5A, in a place where the inclination of the fitting curve is gentle, the difference in the position of the observation point in the horizontal axis direction is appropriately reflected as the difference in the vertical axis direction. However, as shown in the right diagram of FIG. 5A, in a place where the inclination of the fitting curve is steep, the difference in the position of the observation point in the horizontal axis direction is excessively reflected as the difference in the vertical axis direction.

[0029] Next, consider FIG. 5B. As shown in FIG. 5B, in orthogonal distance regression, the difference between the observation point and the fitting curve is evaluated in a direction perpendicular to the fitting curve. Therefore, as shown in the left diagram of FIG. 5B, even in a portion where the fitting curve has a gentle slope, as shown in the right diagram of FIG. 5B, even in a portion where the fitting curve has a steep slope, as shown in the right diagram of FIG. 5B, it can be seen that the difference in the position of the observation point in the horizontal axis direction is appropriately reflected as the difference in the vertical axis direction. From the above, it is clear that the orthogonal distance regression is more accurate than the least squares method in the fitting method of the observation point to the curve. Therefore, in this embodiment, curve fitting is performed using orthogonal distance regression.

[0030] Next, data used when performing fitting will be described. FIG. 6 is an explanatory diagram showing an example of a target list. The target list 121 includes an ID sequence, an azimuth sequence, an elevation sequence, a distance sequence, and a Doppler velocity sequence. The ID sequence stores an ID for identifying each target. The ID may simply be a sequential number. The azimuth sequence stores the azimuth of the target obtained by observation. The elevation sequence stores the elevation of the target obtained by observation. The distance sequence stores the distance to the target obtained by observation. The Doppler velocity sequence stores the Doppler velocity obtained by observation. The target list 121 is created and updated for each observation period. Note that the observation results of the Doppler radar 2 are also used for processing related to the vehicle 3 other than the measurement processing described below. The data items shown in FIG. 6 are items that are particularly necessary for the measurement processing described below, and the target list 121 may include other data items.

[0031] Next, the process performed by the ECU 1 will be described. Fig. 7 is a flowchart showing an example of the procedure of the measurement process. The measurement process is a process that is repeatedly executed by the ECU 1 while the vehicle 3 is traveling straight ahead at a constant speed. For example, the constant speed means that the vehicle speed is 15 to 120 km / h and the acceleration (component excluding the gravitational acceleration) is 1.0 m / s 2 For example, going straight means that the yaw rate is within 1.0 deg / s. The control unit 11 of the ECU 1 acquires the target list 121 (step S1). The control unit 11 judges the driving state of the vehicle 3 (step S2). The driving state is acquired by a process performed by the ECU 1 separately from the measurement process. Depending on the driving state, measurement data suitable for fitting may not be obtained, so this judgment is necessary. The control unit 11 judges whether to continue the process (step S3).

[0032] The guideline for the judgment is as follows, for example: If the vehicle 3 is moving straight, the control unit 11 judges that the processing should be continued. If the vehicle 3 is not moving straight but is traveling on a curve, or is turning right or left at an intersection or the like, or the vehicle 3 is moving within a certain range (for example, ±1.0 m / s 2), the vehicle 3 changes its traveling direction, and thus the state is inappropriate for the measurement process. Therefore, the control unit 11 determines not to continue the process. Whether the vehicle 3 is moving straight or not can be determined by acquiring the amount of turning and the yaw rate of the vehicle from an angular velocity sensor such as a gyro sensor mounted on the vehicle. If the vehicle speed is not within a predetermined range, the control unit 11 determines that the vehicle 3 is inappropriate for the measurement process. This is because, when the vehicle speed is below a predetermined first threshold, the Doppler velocity becomes extremely small, making it difficult to measure and perform accurate fitting. Also, when the vehicle speed is above a predetermined second threshold, the angular velocity of the azimuth angle increases, and thus the measurement accuracy of the azimuth angle decreases, making it difficult to perform accurate fitting. If the absolute value of the acceleration of the vehicle 3 is smaller than a predetermined third threshold, the control unit 11 determines to continue the measurement process. If the absolute value of the acceleration is not small enough, the Doppler velocity changes during the time period in which the reflected wave is received, making it difficult to measure the Doppler velocity with high accuracy, and making it difficult to appropriately correct the error.

[0033] When the control unit 11 determines not to continue the process (NO in step S3), the control unit 11 ends the process in the current cycle. When the control unit 11 determines to continue the process (YES in step S3), the control unit 11 performs filtering of the target to be used for fitting (step S4).

[0034] There are four types of filtering. In the first filtering process, only observation points whose azimuth and elevation angles are within a specified range are processed, and other observation points are excluded from processing. In this process, observation points that are not within the normal field of view are excluded from processing.

[0035] In the second filtering process, observation points for which the amount of change between the azimuth angle measured one cycle ago and the azimuth angle measured this time is less than a predetermined value are processed, and observation points for which the amount of change is equal to or greater than the predetermined value are excluded from the processing. In this process, observation points whose positions have changed significantly are excluded from the processing. Note that the second filtering process does not have to be performed.

[0036] In the third filtering process, the error A from the estimated true value of the azimuth angle of the observation point and the error V from the true value of the vehicle speed of the observation point are used to determine the maximum and minimum values ​​of the Doppler velocity error from the maximum and minimum values ​​of error A and error V. The range of values ​​that the Doppler velocity taking the error into account should take is determined. If the Doppler velocity of the observation point is within this range, it is retained as a processing target, and if it is not within this range, it is excluded from the processing target. In this process, observation points whose observed Doppler velocity is significantly different from the Doppler velocity expected when the target is assumed to be a static target are excluded.

[0037] In the fourth filtering process, the Doppler velocity at each observation point is calculated. The difference between the Doppler velocity at each observation point and the ideal value (an ideal value that does not include error, expressed as -1 * Host V * cos(θ)) is tallied, and the median (or average) of the differences is calculated. If the difference between each observation point and the median is less than a predetermined value, it is left as a processing target, and if it is equal to or greater than the predetermined value, it is excluded from the processing target. In this process, only observation points that are highly likely to be static targets are left as processing targets.

[0038] In the filtering, the first to fourth filtering processes are performed on all observation points, and the observation points determined to be the processing target by all filters are left. Alternatively, the first filtering process may be performed on all observation points, and the second filtering process may be performed on the observation points remaining as the processing target, and so on.

[0039] The control unit 11 determines whether the number of remaining observation points after filtering is equal to or greater than a predetermined threshold (step S5). If the control unit 11 determines that the number of remaining observation points is less than the threshold (NO in step S5), it ends the processing in this cycle. If the control unit 11 determines that the number of remaining observation points is equal to or greater than the threshold (YES in step S5), it performs fitting (step S6).

[0040] In the fitting, the running speed of vehicle 3 is Host V, the azimuth angle of the target is θ, and the Doppler velocity V d Then, the fitting curve shown in equation (2) is set.

[0041] V d = -1 * (Host V + α) * cos(θ + β) … (2)

[0042] The control unit 11 uses the remaining observation points to be processed to find optimal α and β by orthogonal distance regression. For example, the BBS algorithm (algorithm of Boggs, Byrd and Schnabel) is used to find α and β. The BBS algorithm is an algorithm proposed by Paul T. Boggs, Richard H. Byrd, and Robert B. Schnabel. Since it is a well-known algorithm, a detailed explanation is omitted, but the details of the algorithm are disclosed in the following papers, etc.: Paul T. Boggs, Richard H. Byrd, Robert B. Schnabel, "A Stable and Efficient Algorithm for Nonlinear Orthogonal Distance Regression", SIAM Journal on Scientific and Statistical Computing (USA), Society for Industrial and Applied Mathematics, May 1987, Vol. 8, No. 61

[0043] The control unit 11 determines the vehicle speed and the azimuth angle of the mounting angle of the sensor based on the fitting result and the observed Doppler velocity (step S7). The vehicle speed is the extreme value in the fitting curve. The azimuth angle of the mounting angle of the sensor is the azimuth angle showing the extreme value. The control unit 11 stores the determined vehicle speed and the azimuth angle of each target (step S8), and ends the process. As described above, the measurement process shown in FIG. 7 is a periodic process that is periodically repeated.

[0044] Fig. 8 is a graph showing an example of an estimation result. The horizontal axis is time in seconds. The vertical axis is vehicle speed in meters per second. As shown in Fig. 8, compared to the graph of the conventional technology, the graph of this embodiment has less large fluctuations in values ​​and has improved accuracy.

[0045] The present embodiment has the following advantages. Since the orthogonal distance regression is used as the fitting method, instead of the least squares method that has been widely used in the past, it is possible to obtain a highly accurate result. As a result, it is possible to estimate the vehicle speed with high accuracy.

[0046] Since the vehicle speed can be estimated with high accuracy, it is possible to estimate and correct the azimuth angle measurement error using the vehicle speed. That is, by using the above formula (1), θ= acos(V d The azimuth angle measurement error can be estimated from the following equation: / (-1*HostV) In addition, the deviation in the mounting angle of the Doppler radar 2, for example, if the radar is mounted facing 62 degrees counterclockwise from the front of the vehicle instead of facing 60 degrees counterclockwise from the front of the vehicle due to an assembly error, an error of +2 degrees can be detected at the same time as the vehicle speed.

[0047] In the above description, the vehicle 3 is equipped with only the ECU 1 as a control device, but this is not limited thereto. A plurality of ECUs may be provided. When a plurality of ECUs are provided, it is common to provide a main ECU that controls the entire vehicle, and a plurality of sub-ECUs that control each part of the vehicle under the management of the main ECU. In this case, one of the sub-ECUs is the above-mentioned ECU 1, and is named, for example, a radar ECU.

[0048] In the above description, the EUC 1 and the Doppler radar 2 are separate entities, but this is not limiting. In particular, when a sub-ECU including a main ECU and a radar ECU is provided, the radar ECU and the Doppler radar may be integrated into one device.

[0049] When the above-mentioned information system is configured using a CCU (Central Computing Unit), the above-mentioned ECU (Electronic Control Unit) 1 and storage medium 1a are provided in the CCU. The Doppler radar 2 may be provided externally as a satellite radar. Furthermore, the above-mentioned reference data may be data previously generated by the ECU 1 or the CCU itself.

[0050] In the above description, the transmitting antenna 22 and the receiving antenna 24 are each a directional antenna, but this is not limited thereto. Non-directional antennas or omnidirectional antennas may be used as the transmitting antenna 22 and the receiving antenna 24 as long as they can perform the functions required of the transmitting and receiving antennas of the Doppler radar 2.

[0051] Next, another embodiment of the process performed by the ECU 1 will be described. Fig. 9 is a flow chart showing another procedure example of the measurement process. The measurement process is a process that is repeatedly executed by the ECU 1 while the vehicle 3 is traveling straight ahead at a constant speed. For example, the constant speed means that the vehicle speed is 15 to 120 km / h and the acceleration (component excluding the gravitational acceleration) is 1.0 m / s 2 For example, going straight means that the yaw rate is within 1.0 deg / s. The control unit 11 of the ECU 1 acquires the target list 121 (step S11). The control unit 11 determines the driving state of the vehicle 3 (step S12). The driving state is acquired by a process performed by the ECU 1 separately from the measurement process. Depending on the driving state, measurement data suitable for fitting may not be obtained, so the control unit 11 performs the driving state determination. The control unit 11 determines whether or not the process needs to continue based on the result of the driving state determination (step S13).

[0052] The guideline for judging whether or not the process needs to be continued is, for example, as follows: If the vehicle 3 is moving straight, the control unit 11 judges that the process should be continued. If the vehicle 3 is not moving straight but is traveling on a curve, or is turning right or left at an intersection or the like, or the vehicle 3 is moving within a certain range (for example, ±1.0 m / s 2), the vehicle 3 changes its traveling direction or the amount of change in vehicle speed during sampling of the Doppler speed becomes large, so that the state is inappropriate for the measurement process. Therefore, the control unit 11 determines not to continue the process. Whether the vehicle 3 is traveling straight or not can be determined by acquiring the amount of turning or the yaw rate of the vehicle from an angular speed sensor such as a gyro sensor mounted on the vehicle. If the vehicle speed is not within a predetermined range, the control unit 11 determines that the vehicle 3 is in an inappropriate state for the measurement process. This is because if the vehicle speed is below a predetermined first threshold (e.g., 15 km / h), the Doppler speed becomes extremely small, making measurement and accurate fitting difficult. Also, if the vehicle speed is above a predetermined second threshold (e.g., 120 km / h), the angular speed of the azimuth angle becomes large, so that the measurement accuracy of the azimuth angle decreases, making accurate fitting difficult. The control unit 11 determines that the absolute value of the acceleration of the vehicle 3 is equal to or greater than a predetermined third threshold (e.g., ±1.0 m / s 2 ), it is determined that the measurement process should be continued. If the absolute value of the acceleration is not small enough, the Doppler velocity changes during the time period in which the reflected wave is received, making it difficult to measure the Doppler velocity with high accuracy, and making it difficult to appropriately correct the error.

[0053] When the control unit 11 determines not to continue the process (NO in step S13), the control unit 11 ends the process in the current cycle. When the control unit 11 determines to continue the process (YES in step S13), the control unit 11 performs filtering of the target to be used for fitting (step S14). For example, in this embodiment, five types of filtering processes are performed.

[0054] 10 is a flowchart showing an example of the procedure of the filtering process. The control unit 11 performs a first filtering process (step S31). In the first filtering process, only observation points whose azimuth angle (Azimuth) is within a predetermined range and whose elevation angle (Elevation) is within a predetermined range are processed. For example, it is determined whether the predetermined range of the azimuth angle is + / - 75 deg from the front of the Doppler radar and the predetermined range of the elevation angle is + / - 20 deg.

[0055] The control unit 11 performs filtering (step S32). The control unit 11 keeps as processing targets those observation points whose azimuth angle and elevation angle satisfy the conditions, and excludes those that do not. By the first filtering process, the control unit 11 excludes from processing targets observation points that are not within the normal viewing angle.

[0056] The control unit 11 performs a second filtering process (step S33). In the second filtering process, the observation point where the change amount between the azimuth angle measured one cycle ago and the azimuth angle measured this time is less than a predetermined value is processed. For example, it is determined whether the change amount between the azimuth angle of the observation point measured one cycle ago and the azimuth angle measured this time is less than or equal to + / - 20 deg.

[0057] Control unit 11 performs screening (step S34). Control unit 11 keeps as processing targets those observation points whose amount of change in azimuth angle satisfies the condition, and excludes from processing those that do not. In the second filtering process, control unit 11 excludes from processing targets those observation points whose positions have changed significantly through the tracking process of the observation points.

[0058] The control unit 11 performs a third filtering process (step S35). In the third filtering process, the range of error in the observation is taken into consideration, and observation points that are obviously moving relative to the ground are removed, and all observation points that may be stationary are processed. For example, it is determined whether the observation point is observed within the range of maximum and minimum values ​​of Doppler (predetermined value range) that is obtained by using a range of + / -10 deg for the azimuth angle of the observation point and a range of + / -15% for the true value of the vehicle speed.

[0059] The control unit 11 performs screening (step S36). The control unit 11 keeps as processing targets those observation points observed within a predetermined range, and excludes those not observed from processing targets.

[0060] In the fourth filtering process (step S37), the control unit 11 processes observation points that are likely to be static targets, taking into account the effect of the error in the vehicle speed. For example, for each observation point, the ideal value of the Doppler speed is calculated (vehicle speed * cos (azimuth angle)) assuming that the vehicle speed and azimuth angle are accurate, and the observed value of the Doppler speed is compared with the ideal value to obtain the error in the vehicle speed (vehicle speed error = (observed value of Doppler speed / ideal value of Doppler speed) - 1). The median (or average value) is selected from the obtained vehicle speed errors, and this value is set as the provisional vehicle speed error. Using this provisional vehicle speed error, the expected Doppler speed is recalculated for each observation point ((1 + vehicle speed error) * vehicle speed * cos (azimuth angle)), and if the observed Doppler speed is within a certain range, the fourth filtering process is terminated. The control unit 11 returns the process to the caller.

[0061] The control unit 11 performs screening (step S38). For each observation point, only those observation points whose observed Doppler velocities are within a certain range are kept, and those that are not are excluded from processing.

[0062] The control unit 11 performs a fifth filtering process, which is a process of thinning out the observation points in order to improve the accuracy of fitting (step S39). For example, the control unit 11 divides the observation range of the azimuth angle into a plurality of sections each having 1 degree, and leaves a maximum of one (a predetermined number) observation point as a threshold value from each section (same section) as a processing target, and excludes the second and subsequent observation points from the processing target.

[0063] The control unit 11 performs filtering (step S40). For each observation point, only the observation points remaining after the fifth filtering are passed on to the next processing step, and the other observation points are not passed on to the next processing step.

[0064] In the filtering process shown in FIG. 10, a first filtering process is performed on all observation points, and then a second filtering process is performed on the observation points remaining to be processed, and so on. In this manner, filtering is performed in sequence.

[0065] 11 is a flow chart showing another example of the procedure of the filtering process. The control unit 11 performs the first filtering process for all observation points (step S51). The processing contents are as described above. The control unit 11 stores whether or not each observation point has been determined to be a processing target in the first filtering process (step S52).

[0066] The control unit 11 performs the second filtering process for all the observation points (step S53). The processing contents are as described above. The control unit 11 stores whether or not each observation point has been determined as a processing target in the second filtering process (step S54).

[0067] The control unit 11 performs the third filtering process on all the observation points (step S55). The processing contents are as described above. The control unit 11 stores whether or not each observation point has been determined to be a processing target in the third filtering process (step S56).

[0068] The control unit 11 performs a fourth filtering process on all the observation points (step S57). The processing contents are as described above. The control unit 11 stores whether or not each observation point has been determined as a processing target in the fourth filtering process (step S58).

[0069] The control unit 11 performs a fifth filtering process on all the observation points (step S59). The processing contents are as described above. The control unit 11 stores whether or not each observation point has been determined as a processing target in the fifth filtering process (step S60).

[0070] The control unit 11 performs narrowing down (step S61). From among all the observation points, the control unit 11 leaves the observation points that have been determined to be processing targets in all of the filtering processes. The control unit 11 returns the process to the caller.

[0071] The control unit 11 may perform the first to fifth filtering processes (steps S51, S53, S55, S57, and S59) and the subsequent storage processes (steps S52, S54, S56, S58, and S60) in parallel. In this case, the control unit 11 executes step S61 after all filtering processes and storage processes are completed.

[0072] There is no restriction on the order of execution of the first to fifth filtering processes described above or the number of filtering processes to be selected. It is not necessary to execute all of these five filtering processes, and necessary filtering processes may be implemented as appropriate. In addition, filtering processes other than the filtering processes illustrated may be added. For example, the first filtering process, the third filtering process, the fourth filtering process, and the fifth filtering process may be implemented and executed in this order. In addition, the fourth filtering process may be omitted if it is confirmed in the third process, the tracking process described above, or the selection process described above that most or all of the observation points are likely to be stationary with respect to the ground.

[0073] The control unit 11 determines whether the observation points remaining after the filtering process are observed within a predetermined range within the observation range of the azimuth angle of the Doppler radar (step S15). For example, the control unit 11 determines that the remaining observation points are observed within the predetermined range if the maximum and minimum values ​​of the azimuth angle of the remaining observation points are present in a range of 50% or more of the observation range (viewing angle) of the azimuth angle of the Doppler radar. Presence in a range of 50% or more means that, when the Doppler radar has an observation range of ±θ with respect to the azimuth angle, i.e., 2θ, the difference between the maximum and minimum values ​​of the azimuth angle of the remaining observation points is θ or more. If the control unit 11 determines that the remaining observation points are not observed within the predetermined range (NO in step S15), it ends the processing for the current cycle.

[0074] If the control unit 11 determines that the observation points are within the predetermined range (YES in step S15), the control unit 11 performs fitting using the observation points remaining as processing targets in the above processing (step S16). The fitting is the same as the content of step S4 described above, so a description thereof will be omitted.

[0075] The control unit 11 calculates the vehicle speed and the azimuth angle of the mounting angle of the sensor based on the fitting result and the observed Doppler speed (step S17). The content of step S17 is the same as step S7 described above, so the explanation is omitted. The control unit 11 stores the calculated vehicle speed and the azimuth angle of each target (step S18), and ends the process.

[0076] The graph of the estimation results in this embodiment, like that of FIG. 8 referred to above, has improved accuracy compared to the graph of the prior art.

[0077] The technical features (constituent elements) described in each embodiment can be combined with each other, and by combining them, new technical features can be formed. The embodiments disclosed herein are illustrative in all respects and should not be considered as limiting. The scope of the present invention is indicated by the claims, not by the above meaning, and is intended to include all modifications within the meaning and scope of the claims. In addition, the independent claims and dependent claims described in the claims can be combined with each other in all combinations regardless of the reference format. Furthermore, the claims use a format (multiple claim format) in which a claim references two or more other claims, but this is not limited to this. A format in which a multiple claim (multi-multi claim) that references at least one multiple claim may be used. [Explanation of symbols]

[0078] 1: ECU 11: Control section 12: Storage section 121:Target list 13: Communications Department 14: Interface 1P: Control program 1a: Recording medium 2: Doppler radar 21: Transmission unit 22: Transmitting antenna 23: Receiving unit 24: Receiving antenna 3: Vehicle 4:Target

Claims

1. A Doppler radar mounted on a moving body acquires Doppler velocities of a plurality of targets and azimuth angles of the targets relative to the moving body; generating a regression curve showing a relationship between the Doppler velocity and the azimuth angle based on an orthogonal distance from the acquired Doppler velocity and azimuth angle to the regression curve when the velocity, acceleration, and yaw rate of the moving object satisfy a predetermined condition; The speed of the moving object is identified based on the generated regression curve. An information processing method in which processing is performed by a computer.

2. Calculating the azimuth angle of the target based on the velocity and the Doppler velocity of the target. The information processing method according to claim 1 .

3. The azimuth angle is repeatedly output by periodic processing.

3. The information processing method according to claim 1.

4. performing a filtering process including determining whether the target can be regarded as a static target; The target that has passed the filtering process is used as a processing object to generate the regression curve. The information processing method according to claim 3.

5. The filtering process includes: a first filtering process for passing the acquired azimuth angle if the acquired azimuth angle is within a predetermined range; determining a Doppler velocity of the target; a second filtering process for passing the Doppler velocity if the Doppler velocity is within a range of values ​​that should be taken with the error taken into account; A difference between the Doppler velocity of each of the plurality of targets and an ideal value of the Doppler velocity is collected; Calculate the median or average of the differences, The Doppler velocity is recalculated assuming that the determined median or average value is an error. a third filtering process for passing the recalculated Doppler velocity if it is within a predetermined range; The information processing method according to claim 4 , further comprising:

6. performing the second filtering process on the targets that have passed the first filtering process; The third filtering process is performed on the targets that have passed the second filtering process. The information processing method according to claim 5.

7. The first filtering process, the second filtering process, and the third filtering process are performed in parallel for the same target, and only targets that have passed all of the filtering processes are treated as processing targets. The information processing method according to claim 5.

8. generating a regression curve when the number of targets whose azimuth angles fall within a predetermined range is equal to or greater than a threshold value for the targets that have passed the filtering process; A process of identifying the speed of the moving object based on the generated regression curve is performed. The information processing method according to claim 4.

9. Divide the observable azimuth range into intervals, determining in which section the target that has passed the filtering process is included; When a predetermined number of targets are included in the same section, the predetermined number of targets are treated as processing objects, and a regression curve is generated; Identifying the speed of the moving object based on the generated regression curve 9. The information processing method according to claim 8, further comprising the step of:

10. The filtering process includes: a first filtering process for passing the target when the azimuth angle of the target is within a predetermined range; a third filtering process for removing observations where the target is clearly moving relative to the ground and for passing all static targets that may be stationary; a fourth filtering process that removes observation points that are unlikely to be static targets, taking into account the effect of an error in the vehicle speed of the moving body, and passes observation points that are likely to be static targets; The information processing method according to claim 4 , further comprising:

11. The regression curve is obtained using the BBS algorithm.

3. The information processing method according to claim 1.

12. an acquisition unit that acquires Doppler velocities of a plurality of targets and azimuth angles of the targets with respect to the moving body from a Doppler radar mounted on the moving body; a generator that generates a regression curve showing a relationship between a Doppler velocity and an azimuth angle based on an orthogonal distance from the acquired Doppler velocity and azimuth angle to the regression curve when the velocity, acceleration, and yaw rate of the moving object satisfy a predetermined condition; A determination unit that determines the speed of the moving object based on the generated regression curve; An information processing device comprising:

13. A Doppler radar mounted on a moving body acquires Doppler velocities of a plurality of targets and azimuth angles of the targets relative to the moving body; generating a regression curve showing a relationship between the Doppler velocity and the azimuth angle based on an orthogonal distance from the acquired Doppler velocity and azimuth angle to the regression curve when the velocity, acceleration, and yaw rate of the moving object satisfy a predetermined condition; The speed of the moving object is identified based on the generated regression curve. An information processing program that causes a computer to perform processing.

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