JP7564017B2 - Axis offset estimation device - Google Patents

Description

This disclosure relates to a technology for estimating the axis deviation angle of a radar device.

There is known a radar device that is mounted on a moving object and detects targets by receiving reflected waves of irradiated waves at a preset measurement cycle. In this type of radar device, if the installation state changes for some reason, an axis misalignment may occur in which the reference direction of the radar device is misaligned with the reference direction of the moving object as determined by design. When an axis misalignment occurs, the detection error increases, and there is a risk of erroneous detection of the target's azimuth, etc. Therefore, a technology is known that suppresses erroneous detection of the target's azimuth, etc. by estimating the axis misalignment angle, which is the angle of such an axis misalignment.

As one technique for estimating the axis deviation angle, for example, Patent Document 1 discloses a technique for calculating an estimate of the mounting angle of the radar device for each measurement cycle, smoothing the calculated estimated values, and updating the learned value of the mounting angle by taking into account the smoothed value. In the technique disclosed in Patent Document 1, when the learning count, which is the number of updates so far, is less than a predetermined number, the contribution of the estimated value to the learning value is set to be higher compared to when the learning count is equal to or greater than the predetermined number. As a result, in the early stages of learning, the estimated value is more likely to be reflected in the learning value, so that the learning value can be brought closer to the true value quickly, and the time required for the learning value to sufficiently converge can be shortened.

Patent No. 6439728

However, in the technology disclosed in Patent Document 1, the estimated value is likely to be reflected in the learned value in the early stages of learning, regardless of the reliability of the estimated value. Therefore, when learning is started in a driving environment where a highly reliable estimated value is likely to be obtained, the highly reliable estimated value is likely to be reflected in the learned value, so the reliability of the learned value does not decrease, and the estimation accuracy of the axis deviation angle does not decrease. On the other hand, when learning is started in a driving environment where a highly reliable estimated value is difficult to obtain, such as a snowy road environment, the less reliable estimated value is likely to be reflected in the learned value, so the reliability of the learned value decreases, and the estimation accuracy of the axis deviation angle also decreases. In this way, it is thought that the estimation accuracy of the axis deviation angle may differ depending on the driving environment at the start of learning.

Therefore, as a result of detailed investigation by the inventors, it was found that the technology disclosed in Patent Document 1 has an issue in that the effect of reducing the time until the estimation converges is significantly dependent on the driving environment at the start of learning, in other words, the technology has low robustness against the driving environment.

One aspect of the present disclosure provides technology that improves robustness to the driving environment while shortening the time it takes for estimation to converge.

One aspect of the present disclosure is an axis deviation estimation device that estimates an axis deviation angle of a radar device mounted on a moving object, and includes a first calculation unit (4, S40), a second calculation unit (4, S50), and an estimate value update unit (4, S611 to S616, S621 to S624, S631 to S634). The first calculation unit calculates a latest estimate value that is an estimate value of the latest axis deviation angle based on target information that is information on targets detected by the radar device. The second calculation unit calculates an estimate reliability that is a reliability of the latest estimate value. The estimate value update unit updates an output estimate value that is a value output as an estimate result of the axis deviation angle by taking into account the latest estimate value. In addition, when the estimate reliability is the first reliability, the estimate value update unit increases the degree of contribution of the latest estimate value to the output estimate value compared to when the estimate reliability is the second reliability that is lower than the first reliability.

This configuration can reduce the time it takes for the estimation to converge while improving robustness to the driving environment.

1 is a block diagram showing a configuration of a vehicle control system according to a first embodiment; FIG. 4 is an explanatory diagram illustrating an irradiation range of a radar wave in the vertical direction. FIG. 2 is an explanatory diagram illustrating a horizontal irradiation range of a radar wave. FIG. 4 is an explanatory diagram for explaining the azimuth angle and axis shift of a reflection point. 4 is a flowchart of an axis shift estimation process according to the first embodiment. 10 is a flowchart of an output value update process according to the first embodiment. 13 is a flowchart of an output value update process according to the second embodiment. 13 is a flowchart of an output value update process according to the third embodiment.

Hereinafter, exemplary embodiments of the present disclosure will be described with reference to the drawings.
[1. First embodiment]
[1-1. Configuration]
The vehicle control system 1 shown in Fig. 1 is a system mounted on a vehicle. The vehicle control system 1 includes a radar device 2, an on-vehicle sensor group 3, a signal processing unit 4, an assistance execution unit 5, and an axis deviation notification device 6. Hereinafter, the vehicle on which the vehicle control system 1 is mounted is also referred to as the host vehicle. The vehicle height direction of the host vehicle is also referred to as the vertical direction, and the vehicle width direction of the host vehicle is also referred to as the horizontal direction.

The radar device 2 includes an antenna unit that transmits and receives radar waves. The antenna unit is configured to detect the direction of arrival of reflected waves in both the vertical and horizontal directions. In this embodiment, the antenna unit is an array antenna that includes multiple antennas arranged vertically and horizontally.

As shown in Figs. 2 and 3, the radar device 2 is mounted on the front side of the vehicle VH. The radar device 2 irradiates radar waves in an irradiation range that is a predetermined angular range in front of the vehicle VH. Specifically, the radar device 2 irradiates radar waves in an irradiation range Rv in the vertical direction and an irradiation range Rh in the horizontal direction, and receives reflected waves of the irradiated radar waves. The radar device 2 detects targets present in the irradiation range for each predetermined measurement cycle by periodically irradiating radar waves to the entire irradiation range and receiving reflected waves. Target information, which is information on targets detected by the radar device 2, includes at least information indicating the azimuth angle of the reflection point that reflected the radar wave and the relative speed q between the radar device 2 and the reflection point. The target information is output to the signal processing unit 4 for each measurement cycle.

The azimuth angle of the reflection point is at least one of the vertical angle (hereinafter, vertical angle) Ver and the horizontal angle (hereinafter, horizontal angle) Hor among the angles of the reflection point obtained based on the reference direction A of the radar device 2 as shown in FIG. 4. In this embodiment, both the vertical angle Ver and the horizontal angle Hor are included in the target information as information representing the azimuth angle of the reflection point. The vertical angle Ver is expressed as an angle in which the reference direction A of the radar device 2 is the reference (i.e., 0°) when the vehicle VH is viewed from the right side, and the rightward angle is positive and the leftward angle is negative from the reference direction A of the radar device 2 when the vehicle VH is viewed from the sky, and the reference direction A of the radar device 2 is the reference, and the rightward angle is positive and the leftward angle is negative. The reference direction A of the radar device 2 is the direction of the radar device 2 that is determined as a reference in the design. In this embodiment, the direction of the central axis of the irradiation range is set as the reference direction A of the radar device 2. In this embodiment, the radar device 2 is mounted on the host vehicle VH so that the reference direction A of the radar device 2 coincides with the reference direction of the vehicle. The reference direction of the vehicle is the direction of the vehicle that is determined as a reference in terms of design, and in this embodiment, the traveling direction B of the host vehicle VH is set as the reference direction of the vehicle. When the radar device 2 is mounted on the host vehicle VH so that the reference direction A of the radar device 2 coincides with the traveling direction B of the host vehicle VH, the azimuth angle of the detected reflection point coincides with the angle of the reflection point relative to the traveling direction B of the host vehicle VH. In other words, if there is a deviation between the reference direction A of the radar device 2 and the traveling direction B of the host vehicle VH, information indicating the angle of the reflection point relative to the traveling direction B of the host vehicle VH will not be obtained correctly.

4 shows a state in which the radar device 2 has an axis deviation in the vertical direction, that is, an axis deviation in the xz plane, which is a vertical surface. The axis deviation refers to a state in which the reference direction A of the radar device 2 is deviated from the reference direction of the vehicle (in this embodiment, the traveling direction B of the host vehicle VH). The axis deviation angle refers to an angle indicating the magnitude of deviation between the reference direction A of the radar device 2 and the reference direction of the vehicle (in this embodiment, the traveling direction B of the host vehicle VH). Hereinafter, the axis deviation angle in the vertical direction is referred to as the vertical axis deviation angle α _v , and the axis deviation angle in the horizontal direction is referred to as the horizontal axis deviation angle α _h .

In this embodiment, the radar device 2 employs a known FMCW method, which alternately transmits radar waves in the uplink modulation section and radar waves in the downlink modulation section at a preset modulation period, and receives the reflected radar waves. FMCW stands for Frequency Modulated Continuous Wave. As a result, the radar device 2 detects a target for each modulation period, and outputs the relative speed q, vertical angle Ver, and horizontal angle Hor as target information to the signal processing unit 4. The radar device 2 can also output the distance to the reflection point and the reception power of the received radar wave to the signal processing unit 4 as target information.

Returning to FIG. 1, the on-vehicle sensor group 3 is a variety of sensors mounted on the host vehicle VH to detect the state of the host vehicle VH, etc. The sensors that make up the on-vehicle sensor group 3 include at least a vehicle speed sensor that detects the moving object speed Cm, which is the speed of the host vehicle VH, based on the rotation of the wheels. The detected moving object speed Cm is output to the signal processing unit 4.

The signal processing unit 4 is mainly composed of a microcomputer (hereinafter, a microcomputer) having a CPU 41, a ROM 43, a RAM 44, a semiconductor memory such as a flash memory (hereinafter, a memory 42). The various functions of the signal processing unit 4 are realized by the CPU 41 executing a program stored in a non-transitive real recording medium. In this example, the memory 42 corresponds to the non-transitive real recording medium storing the program. In addition, the program is executed to execute a method corresponding to the program. The number of microcomputers constituting the signal processing unit 4 may be one or more. In addition, the method of realizing the various functions of the signal processing unit 4 is not limited to software, and some or all of the elements may be realized using one or more hardware. For example, when the above functions are realized by an electronic circuit that is hardware, the electronic circuit may be realized by a digital circuit including a large number of logic circuits, an analog circuit, or a combination of these.

The processes executed by the signal processor 4 include at least an axis offset estimation process and a target recognition process.
Among these, the axis deviation estimation process is a process for estimating an axis deviation angle of the radar device 2 and calculating an output estimation value M which is a value output as an estimation result of the axis deviation angle of the radar device 2. The axis deviation estimation process will be described in detail later. The estimation result in the axis deviation estimation process is output to the axis deviation notification device 6, etc.

On the other hand, the target recognition process is a process for detecting the lane in which the host vehicle VH is traveling, a preceding vehicle traveling in the same lane as the host vehicle VH, other vehicles, obstacles, etc., based on the target information obtained from the radar device 2 and various information obtained from the on-board sensor group 3. Note that the target information may be corrected based on the estimation result in the axis deviation estimation process. The processing result in the target recognition process is output to the assistance execution unit 5, etc.

The assistance execution unit 5 controls various in-vehicle devices to perform predetermined driving assistance based on the results of the target recognition processing output from the signal processing unit 4. The in-vehicle devices to be controlled include monitors that display various images, audio equipment that outputs warning sounds and guidance voices, and may also include control devices that control the internal combustion engine, powertrain mechanism, brake mechanism, etc. of the host vehicle VH.

The axis deviation notification device 6 is an audio output device installed in the vehicle cabin. The axis deviation notification device 6 outputs an alarm sound to the occupants of the vehicle VH based on the estimation result of the axis deviation estimation process output from the signal processing unit 4.

[1-2. Processing]
[1-2-1. Axis offset estimation process]
Next, the axis offset estimation process executed by the signal processor 4 will be described with reference to the flowchart shown in Fig. 5. This process is started when the ignition switch is turned on, and ends when the ignition switch is turned off.

When this process is started, in S10, the signal processing unit 4 inputs target information from the radar device 2. Note that the processes from S10 to S30 are performed for each measurement cycle.
Next, in S20, the signal processor 4 extracts, from the reflection points included in the target information, reflection points that are assumed to be points where the radar wave is reflected by a stationary object, as stationary reflection points. The extraction of stationary reflection points can be performed by various known methods.

Then, the signal processing unit 4 uses the extracted still reflection points to calculate a cycle estimate C, which is an estimate of the axis deviation angle calculated for each measurement cycle. Note that the signal processing unit 4 may select still reflection points that satisfy a predetermined condition from the extracted still reflection points, and calculate the cycle estimate C using the selected still reflection points.

In the following, an example is shown of calculating a vertical cycle estimate C _v which is an estimate of a vertical axis shift angle α _v calculated for each measurement. Note that a horizontal cycle estimate C _h which is an estimate of a horizontal axis shift angle α _h calculated for each measurement can also be calculated in a similar manner. For example, the signal processing unit 4 calculates the vertical cycle estimate C _v according to equation (1).

Here, Ver' is the vertical angle when no axial deviation occurs in the radar device 2, and Ver is the vertical angle for each stationary reflection point included in the target information acquired from the radar device 2 in S10. q _v is the magnitude in the xz plane of the relative speed q of the stationary reflection point, and Cm _v is the magnitude in the xz plane of the moving object speed Cm input from the on-board sensor group 3. γ _v is the vertical moving object speed error, which is the magnitude in the xz plane of the moving object speed error γ, which is the speed error included in the moving object speed Cm.

Based on equation (1), an equation is obtained for each stationary reflection point with the vertical cycle estimated value C _v and the vertical moving body velocity error γ _v as unknown parameters. In other words, the same number of simultaneous equations as the number of extracted stationary reflection points are obtained. By solving these simultaneous equations, the vertical cycle estimated value C _v and the vertical moving body velocity error γ _v are obtained. As a specific method for solving the simultaneous equations, for example, the least squares method can be used. However, the method for solving the simultaneous equations is not limited to the least squares method.

Next, in S30, the signal processing unit 4 determines whether the cycle estimation number Ncy, which is the number of times the cycle estimation value C is calculated, is less than J times. J is any integer equal to or greater than 2. In this embodiment, the signal processing unit 4 increments the cycle estimation number Ncy by 1 each time the cycle estimation value C is calculated. Note that the cycle estimation number Ncy at the start of the axis deviation estimation process is 0 times. If the signal processing unit 4 determines that the cycle estimation number Ncy is less than J times, it returns to S10. If the signal processing unit 4 determines that the cycle estimation number Ncy is not less than J times, it proceeds to S40. That is, the processes from S10 to S20 are repeated J times.

In S40, the signal processing unit 4 calculates a latest estimated value m, which is an estimate of the latest axis deviation angle. In this embodiment, the signal processing unit 4 smoothes J cycle estimated values C calculated in the most recent J measurement cycles (hereinafter, smoothing intervals) including the current measurement cycle to calculate the latest estimated value m. As a smoothing method, for example, a method of taking the arithmetic mean of the J cycle estimated values C calculated in the smoothing interval can be used. However, the smoothing method is not limited to this, and for example, a method of extracting cycle estimated values C that satisfy a predetermined condition from the J cycle estimated values C calculated in the smoothing interval and taking the arithmetic mean of the extracted cycle estimated values C can also be used.

Next, in S50, the signal processing unit 4 calculates the estimation reliability w, which is the reliability of the latest estimation value m. In this embodiment, the signal processing unit 4 calculates a value representing the smallness of the variation of the J cycle estimation values C calculated in the smoothing section as the estimation reliability w. More specifically, in this embodiment, the signal processing unit 4 calculates the reciprocal of the standard deviation of the J cycle estimation values C calculated in the smoothing section as the estimation reliability w. However, the estimation reliability w is not limited to this, and for example, the estimation reliability w may be a value representing the smallness of the difference between the maximum and minimum cycle estimation values C among the J cycle estimation values C calculated in the smoothing section.

Next, in S60, the signal processing unit 4 executes an output value update process to update the output value based on the latest estimated value m calculated in S40 and the estimated reliability w calculated in S50. The output value includes an output estimated value M and an output value reliability W, which is the reliability of the output estimated value M. The output value update process will be described later. The signal processing unit 4 outputs at least the output estimated value M of the updated output values to the axis deviation notification device 6, etc.

Next, in S70, the signal processing unit 4 resets the estimated cycle number Ncy to 0. After that, the signal processing unit 4 returns to S10.
[1-2-2. Output value update process]
Next, the output value update process executed in S60 will be described with reference to the flowchart shown in Fig. 6. Here, the output estimate value M before being updated in the output value update process is referred to as the current output estimate value Mn _-1 , the output estimate value M after being updated in the output value update process is referred to as the updated output estimate value _Mn , the output value reliability W before being updated in the output value update process is referred to as the current output value reliability Wn _-1 , and the output value reliability W after being updated in the output value update process is referred to as the updated output value reliability _Wn .

First, in S611, the signal processing unit 4 judges whether or not the estimation reliability w calculated in S50 and the absolute value Dm of the estimation value difference, which is the difference between the latest estimation value m and the current output estimation value M _n-1 calculated in S40, satisfy a first condition. The first condition is a condition in which the estimation reliability w is greater than an estimation reliability threshold THw, which is a predetermined threshold, and the absolute value Dm of the estimation value difference is greater than a difference threshold THm, which is a predetermined threshold. If the signal processing unit 4 judges that the estimation reliability w and the absolute value Dm of the estimation value difference satisfy the first condition, it proceeds to S613. If the signal processing unit 4 judges that the estimation reliability w and the absolute value Dm of the estimation value difference do not satisfy the first condition, it proceeds to S612.

In S612, the signal processing unit 4 determines whether the estimation reliability w satisfies the second condition. The second condition is that the estimation reliability w is greater than the estimation reliability threshold THw. If the signal processing unit 4 determines that the estimation reliability w satisfies the second condition, it transitions to S614. If the signal processing unit 4 determines that the estimation reliability w does not satisfy the second condition, it transitions to S615.

In S613, the signal processing unit 4 sets the update coefficient k, which is a coefficient used when updating the output value, to the first update coefficient K1. The first update coefficient K1 is a value greater than 0 and less than or equal to 1. After that, the signal processing unit 4 proceeds to S616.

In S614, the signal processing unit 4 sets the update coefficient k to the second update coefficient K2. The second update coefficient K2 is a value greater than 0 and less than the first update coefficient K1. After that, the signal processing unit 4 proceeds to S616.

In S615, the signal processing unit 4 sets the update coefficient k to the third update coefficient K3. In this embodiment, the third update coefficient K3 is 0. However, the third update coefficient K3 is not limited to 0, and may be, for example, a value greater than 0 and less than the second update coefficient K2. After that, the signal processing unit 4 proceeds to S616.

The process of S611 to S615 is a process of setting the update coefficient k to one of the first update coefficient K1, the second update coefficient K2, and the third update coefficient K3 based on the estimation reliability w and the absolute value Dm of the estimated value difference. That is, when the estimation reliability w is greater than the estimation reliability threshold THw and the absolute value Dm of the estimated value difference is greater than the difference threshold THm, the signal processing unit 4 sets the update coefficient k to the first update coefficient K1, which has the largest value. When the estimation reliability w is greater than the estimation reliability threshold THw and the absolute value Dm of the estimated value difference is equal to or less than the difference threshold THm, the signal processing unit 4 sets the update coefficient k to the second update coefficient K2. When the estimation reliability w is equal to or less than the estimation reliability threshold THw, the signal processing unit 4 sets the update coefficient k to the third update coefficient K3, which has the smallest value.

In S616, the signal processing unit 4 calculates an updated output estimate M n according to equation (2) using the update coefficient _k set in the processes of S611 to S615, the latest estimate m, and the current output estimate M _n-1 .

Next, in S617, the signal processing unit 4 calculates the update output value reliability W n according to equation (3) using the update coefficient k, the estimated reliability w, and the current output value reliability W _{n-1 set} in the processes of S611 to S615.

Then, the signal processing unit 4 ends the output value update process.
As is clear from equation (2), the update coefficient k is the degree of contribution of the latest estimated value m to the updated output estimated value _Mn . Also, as is clear from equation (3), the update coefficient k can be said to be the degree of contribution of the estimation reliability w to the updated output value reliability _Wn .

That is, when the estimation reliability w is the first reliability, the signal processing unit 4 updates the output value by increasing the contribution degree of the latest estimated value m to the updated output estimated value _Mn and the contribution degree of the estimation reliability w to the updated output value reliability _Wn, compared to when the estimation reliability w is a second reliability lower than the first reliability. Also, when the absolute value Dm of the estimate value difference is the first absolute value, the signal processing unit 4 updates the output value by increasing the contribution degree of the latest estimated value m to the updated output estimated value _Mn and the contribution degree of the estimation reliability w to the updated output value reliability _Wn, compared to when the absolute value Dm of the estimate value difference is a second absolute value lower than the first absolute value.

[1-3. Effects]
According to the first embodiment described above in detail, the following effects can be obtained.
(1a) The signal processor 4 is configured to calculate an updated output estimate _Mn by taking into account the latest estimate m. When the estimation reliability w is a first reliability, the signal processor 4 is configured to increase the contribution of the latest estimate m to the updated output estimate _Mn , compared to when the estimation reliability w is a second reliability lower than the first reliability.

According to this configuration, the latest estimated value m with low reliability is unlikely to be reflected in the updated output estimated value _Mn , so that even if learning is started in a driving environment in which it is difficult to obtain a latest estimated value m with high reliability, it is possible to suppress a decrease in the estimation accuracy of the axis deviation angle. In other words, it is possible to suppress a difference in the estimation accuracy of the axis deviation angle depending on the driving environment at the start of learning. Therefore, it is possible to improve robustness against the driving environment while shortening the time until the estimation of the axis deviation angle converges.

(1b) The signal processing unit 4 is configured to smooth a cycle estimated value C, which is an estimate of the axis deviation angle for each measurement cycle, to calculate a latest estimated value m.
With this configuration, the influence of the error contained in the cycle estimate value C on the updated output estimate value M _n can be suppressed.

(1c) When the absolute value Dm of the estimate value difference, which is the difference between the latest estimate value m and the current output estimate value M _n-1, is a first absolute value, the signal processing unit 4 is configured to increase the degree of contribution of the latest estimate value m to the updated output estimate value M _n compared to when the absolute value Dm of the estimate value difference is a second absolute value lower than the first absolute value.

According to this configuration, when the latest estimated value m is significantly different from the current output estimated value M _n-1 , that is, when the latest estimated value m is changing suddenly, the latest estimated value m can be updated with an increased contribution of the latest estimated value m to the updated output estimated value M _n . Therefore, compared to a configuration in which the output value update process is redone when the latest estimated value m is changing suddenly, for example, the time until the estimation of the axis deviation angle converges can be shortened.

(1d) The signal processing unit 4 is configured to increase the contribution of the latest estimated value m to the updated output estimated value M _n when the estimation reliability w is the first reliability and the latest estimated value m is changing suddenly.

According to this configuration, when the latest estimated value m has changed suddenly but its reliability is high, the contribution of the latest estimated value m to the updated output estimated value _Mn can be increased to calculate the updated output estimated value _Mn . Therefore, compared to a configuration in which the output value update process is redone when the latest estimated value m has changed suddenly, it is possible to reduce the time until the estimation of the axis deviation angle converges while suppressing a decrease in the estimation accuracy of the axis deviation angle.

(1e) The signal processing unit 4 is configured to set the contribution degree of the latest estimated value m to the updated output estimated value M _n to 0 when the estimation reliability w is equal to or smaller than an estimation reliability threshold THw.
According to this configuration, it is possible to prevent the latest estimated value m having low reliability from being reflected in the updated output estimated value M _n , and therefore it is possible to prevent the estimation accuracy of the axis deviation angle from decreasing.

[1-4. Modifications]
In the first embodiment, the signal processing unit 4 determines whether the estimation reliability w satisfies the second condition in S612, and sets the update coefficient k to the second update coefficient K2 if it is determined that the estimation reliability w satisfies the second condition, and sets the update coefficient k to the third update coefficient K3 if it is determined that the estimation reliability w does not satisfy the second condition. However, the method of setting the update coefficient k is not limited to this. For example, the signal processing unit 4 may set the update coefficient k more finely in S612 according to the value of the estimation reliability w. In this case, the update coefficient k is set so that the larger the value of the estimation reliability w, the larger the update coefficient k.

[2. Second embodiment]
The second embodiment has a basic configuration similar to that of the first embodiment, and therefore differences will be described below. Note that the same reference numerals as those in the first embodiment indicate the same configurations, and the preceding description will be referred to.

[2-1. Processing]
The second embodiment differs from the first embodiment in that the output value update process shown in Fig. 7 is executed instead of the output value update process shown in Fig. 6. The output value update process shown in Fig. 7 differs from the output value update process shown in Fig. 6 in that the process of S621 to S625 is executed instead of the process of S611 to S617. However, the process of S621 and S624 to S625 is the same as the process of S611 and S616 to S617.

In S621, if the signal processing unit 4 determines that the estimation reliability w and the absolute value of the estimated value difference Dm satisfy the first condition, it transitions to S622, and if it determines that the estimation reliability w and the absolute value of the estimated value difference Dm do not satisfy the first condition, it transitions to S623.

In S622, the signal processing unit 4 sets the update coefficient k to the fourth update coefficient K4. After that, the signal processing unit 4 proceeds to S624. The fourth update coefficient K4 is calculated according to formula (4). However, if the fourth update coefficient K4 calculated according to formula (4) is a value greater than 1, the signal processing unit 4 sets the update coefficient k to 1.

Here, the difference threshold value THm is the same as the difference threshold value THm, which is the predetermined threshold value included in the first condition. However, the difference threshold value THm in the formula (4) is not limited to this, and a value different from the difference threshold value THm, which is the predetermined threshold value included in the first condition, may be set. Also, the first update coefficient K1 is a value greater than 0 and equal to or less than 1, as in the first embodiment. The fifth update coefficient K5 is a value greater than 0 and less than the first update coefficient K1.

In S623, the signal processor 4 sets the update coefficient k to a fifth update coefficient K5. After that, the signal processor 4 proceeds to S624.
The process of S621 to S623 is a process of setting the update coefficient k to the fourth update coefficient K4 or the fifth update coefficient K5 based on the estimation reliability w and the absolute value Dm of the estimated value difference. That is, when the estimation reliability w is greater than the estimation reliability threshold THw and the absolute value Dm of the estimated value difference is greater than the difference threshold THm, the signal processing unit 4 sets the update coefficient k to the fourth update coefficient K4 according to the formula (4). As is clear from the formula (4), the fourth update coefficient K4 is not smaller than the fifth update coefficient K5. Moreover, the fourth update coefficient K4 is proportional to the magnitude of the absolute value Dm of the estimated value difference in the range of the fifth update coefficient K5 or more. On the other hand, when the estimation reliability w is equal to or less than the estimation reliability threshold THw or the absolute value Dm of the estimated value difference is equal to or less than the difference threshold THm, the signal processing unit 4 sets the update coefficient k to the fifth update coefficient K5 which is equal to or less than the fourth update coefficient K4.

Here, the configuration in S622 for setting the fourth update coefficient K4 in proportion to the magnitude of the absolute value Dm of the estimated value difference is expressed as a difference proportional section.
[2-2. Effects]
According to the second embodiment described above in detail, in addition to the effects (1a) to (1e) of the first embodiment described above, the following effects can be obtained.

(2a) The signal processing unit 4 of this embodiment is configured to include a difference proportional unit that increases the contribution of the latest estimated value _{m to the updated output estimated value Mn} in proportion to the magnitude of the absolute value Dm of the estimated value difference.

According to this configuration, the greater the deviation between the latest estimated value m and the current output estimated value Mn _-1 , that is, the greater the degree of sudden change in the latest estimated value m, the higher the contribution degree of the latest estimated value _m to the update output estimated value _Mn can be calculated. In other words, since the contribution degree of the latest estimated value m to the update output estimated value _Mn can be set according to the degree of sudden change in the latest estimated value m, and the update output estimated value _Mn can be calculated, it is possible to suppress a decrease in the estimation accuracy of the axis deviation angle even if the latest estimated value m changes suddenly.

[3. Third embodiment]
The third embodiment has a basic configuration similar to that of the first embodiment, and therefore differences will be described below. Note that the same reference numerals as those in the first embodiment indicate the same configurations, and the preceding description will be referred to.

[3-1. Processing]
The third embodiment differs from the first embodiment in that the output value update process shown in Fig. 8 is executed instead of the output value update process shown in Fig. 6. The output value update process shown in Fig. 8 differs from the output value update process shown in Fig. 6 in that the process of S631 to S635 is executed instead of the process of S611 to S617. However, the process of S631 and S634 to S635 is the same as the process of S611 and S616 to S617.

In S631, if the signal processing unit 4 determines that the estimation reliability w and the absolute value of the estimated value difference Dm satisfy the first condition, it transitions to S632, and if it determines that the estimation reliability w and the absolute value of the estimated value difference Dm do not satisfy the first condition, it transitions to S633.

In S632, the signal processing unit 4 sets the update coefficient k to the sixth update coefficient K6. After that, the signal processing unit 4 proceeds to S634. The sixth update coefficient K6 is calculated according to formula (5). However, if the sixth update coefficient K6 calculated according to formula (5) is a value greater than 1, the signal processing unit 4 sets the update coefficient k to 1.

Here, similarly to the first embodiment, the first update coefficient K1 is a value greater than 0 and equal to or less than 1. The seventh update coefficient K7 is a value greater than or equal to 0 and smaller than the first update coefficient K1.
In S633, the signal processor 4 sets the update coefficient k to the seventh update coefficient K7. After that, the signal processor 4 proceeds to S634.

The processing of S631 to S633 is processing for setting the update coefficient k to the sixth update coefficient K6 or the seventh update coefficient K7 based on the estimation reliability w and the absolute value Dm of the estimated value difference. That is, when the estimation reliability w is greater than the estimation reliability threshold THw and the absolute value Dm of the estimated value difference is greater than the difference threshold THm, the signal processing unit 4 sets the update coefficient k to the sixth update coefficient K6 according to the formula (5). As is clear from the formula (5), the sixth update coefficient K6 is not smaller than the seventh update coefficient K7. Moreover, the sixth update coefficient K6 is proportional to the magnitude of the ratio of the estimation reliability w to the current output value reliability W _n-1 in the range of the seventh update coefficient K7 or more. On the other hand, when the estimation reliability w is equal to or less than the estimation reliability threshold THw or the absolute value Dm of the estimated value difference is equal to or less than the difference threshold THm, the signal processing unit 4 sets the update coefficient k to the seventh update coefficient K7, which is equal to or less than the sixth update coefficient K6.

Here, the configuration in S632 for setting the sixth update coefficient K6 in proportion to the magnitude of the ratio of the estimation reliability w to the current output value reliability W _n-1 is represented as a ratio proportional section.
[3-2. Effects]
According to the third embodiment described above in detail, in addition to the effects (1a) to (1e) of the first embodiment described above, the following effects can be obtained.

(3a) The signal processing unit 4 of this embodiment is configured to include a ratio proportional section that increases the contribution of the latest estimated value m to the updated output estimated value M _n in proportion to the ratio of the estimation reliability _w to the current output value reliability W n-1.

According to this configuration, the greater the ratio of the estimation reliability w to the current output value reliability Wn _-1 , that is, the greater the degree of increase in the estimation reliability w, the greater the contribution of the latest estimated value m to the update output estimate value _Mn, thereby making it possible to calculate the update output estimate value _Mn . In other words, when the estimation reliability w rises sharply, the latest estimated value m, which has a higher reliability than the current output estimate value Mn _-1 , is more likely to be reflected in the update output estimate value _Mn , thereby improving the estimation accuracy of the axis deviation angle.

4. Other embodiments
Although the embodiments of the present disclosure have been described above, it goes without saying that the present disclosure is not limited to the above-described embodiments and can take various forms.

(4a) In the above embodiment, the signal processing unit 4 smoothes multiple cycle estimate values C to calculate the latest estimate value m in S40. However, smoothing is not essential. For example, the signal processing unit 4 may use one cycle estimate value C calculated in S20 as the latest estimate value m without smoothing it. In this case, the process of S30 may be omitted.

In this case, the estimation reliability w calculated in S50 may be calculated based on information obtained in the process of calculating the cycle estimation value C in S20, for example, the number of stationary reflection points used to calculate the cycle estimation value C.

(4b) In the above embodiment, the signal processing unit 4 executes the processes of S30 to S50 in sequence, but the order in which the processes are executed is not limited to this. For example, the signal processing unit 4 may execute the process of S30 after the processes of S40 and S50.

In this case, the signal processing unit 4 smoothes the cycle estimate value C for each measurement cycle, and calculates a provisional estimate value t, which is a provisional estimate value of the axis deviation angle, for each measurement cycle. That is, the signal processing unit 4 smooths the provisional estimate value t and the cycle estimate value C to calculate a new provisional estimate value t for each measurement cycle. Then, the provisional estimate value t calculated after smoothing is repeated J times is set as the latest estimate value m.

(4c) In the above embodiment, the radar device 2 transmits radar waves toward the front of the vehicle VH, but the transmission direction of the radar waves is not limited to the front of the vehicle VH. For example, the radar device 2 may be configured to transmit radar waves toward at least one of the front, front right, front left, rear, rear right, rear left, right side, and left side of the vehicle VH.

(4d) In the above embodiment, the radar device 2 outputs target information including both the vertical angle Ver and the horizontal angle Hor as information representing the azimuth angle of the reflection point to the signal processing unit 4, but the target information output by the radar device 2 is not limited to this. For example, the target information may include only the vertical angle Ver as information representing the azimuth angle of the reflection point, or may include only the horizontal angle Hor as information representing the azimuth angle of the reflection point.

(4e) In the above embodiment, an example was shown in which the radar device 2 adopted the FMCW method, but the radar method of the radar device 2 is not limited to FMCW, and may be configured to adopt, for example, two-frequency CW, FCM, or pulse. FCM is an abbreviation for Fast-Chirp Modulation.

(4f) In the above embodiment, an audio output device installed in the vehicle cabin is used as the axis deviation notification device 6, but the axis deviation notification device 6 is not limited to this. For example, an audio device or the like provided in the assistance execution unit 5 may be used as the axis deviation notification device 6.

(4g) The functions of one component in the above embodiments may be distributed among multiple components, or the functions of multiple components may be integrated into one component. In addition, part of the configuration of the above embodiments may be omitted. In addition, at least part of the configuration of the above embodiments may be added to or substituted for the configuration of another of the above embodiments.

(4h) The present disclosure can be realized in various forms, such as the axis offset estimation device described above, a vehicle control system 1 including the axis offset estimation device, a program for causing a computer to function as the axis offset estimation device, a medium on which the program is recorded, and an axis offset estimation method.

In the above embodiment, the signal processing unit 4 corresponds to the axis deviation estimation device. Also, S40 corresponds to the processing as the first calculation unit, S50 corresponds to the processing as the second calculation unit, S611 to S616, S621 to S624, and S631 to S634 correspond to the processing as the estimated value update unit, S617, S625, and S635 correspond to the processing as the reliability update unit, S632 corresponds to the processing as the ratio proportional unit, and S622 corresponds to the processing as the difference proportional unit. Also, the host vehicle VH corresponds to the moving body.

1...vehicle control system, 2...radar device, 3...vehicle-mounted sensor group, 4...signal processing unit, 41...CPU, 42...memory, 43...ROM, 44...RAM.

Claims (9)

An axis shift estimation device that estimates an axis shift angle of a radar device mounted on a moving object, comprising:
a first calculation unit (4, S40) that calculates a latest estimated value of the axis deviation angle based on target information that is information on a target detected by the radar device;
A second calculation unit (4, S50) for calculating an estimated reliability which is a reliability of the latest estimated value;
an estimate value update unit (4, S611 to S616, S621 to S624, S631 to S634) that updates an output estimate value that is a value output as a result of estimating the axis deviation angle, taking into account the latest estimate value;
Equipped with
the estimate value update unit is configured to increase a contribution degree of the latest estimate value to the output estimate value when the estimation reliability is a first reliability, compared to when the estimation reliability is a second reliability lower than the first reliability;
the first calculation unit is configured to calculate a cycle estimate value that is an estimate value of the axis deviation angle for each measurement cycle based on the target information for each measurement cycle that is set in advance, and to calculate the latest estimate value by smoothing a plurality of the cycle estimate values;
The axis shift estimation device, wherein the estimation reliability is calculated as a value representing the smallness of variation among the plurality of cycle estimates. An axis shift estimation device that estimates an axis shift angle of a radar device mounted on a moving object, comprising:
a first calculation unit (4, S40) that calculates a latest estimated value of the axis deviation angle based on target information that is information on a target detected by the radar device;
A second calculation unit (4, S50) for calculating an estimated reliability which is a reliability of the latest estimated value;
an estimate value update unit (4, S611 to S616, S621 to S624, S631 to S634) that updates an output estimate value that is a value output as a result of estimating the axis deviation angle, taking into account the latest estimate value;
Equipped with
the estimate value update unit is configured to increase a contribution degree of the latest estimate value to the output estimate value when the estimation reliability is a first reliability, compared to when the estimation reliability is a second reliability lower than the first reliability;
the estimate value updating unit increases the degree of contribution when an absolute value of a difference between the output estimate value and the latest estimate value is a first absolute value, compared to when the absolute value of the difference is a second absolute value smaller than the first absolute value. An axis shift estimation device that estimates an axis shift angle of a radar device mounted on a moving object, comprising:
a first calculation unit (4, S40) that calculates a latest estimated value of the axis deviation angle based on target information that is information on a target detected by the radar device;
A second calculation unit (4, S50) for calculating an estimated reliability which is a reliability of the latest estimated value;
an estimate value update unit (4, S611 to S616, S621 to S624, S631 to S634) that updates an output estimate value that is a value output as a result of estimating the axis deviation angle, taking into account the latest estimate value;
Equipped with
the estimate value update unit is configured to increase a contribution degree of the latest estimate value to the output estimate value when the estimation reliability is a first reliability, compared to when the estimation reliability is a second reliability lower than the first reliability;
The method further includes a reliability update unit (4, S617, S625, S635) that updates an output value reliability, which is a reliability of the output estimated value, by taking into account the estimation reliability,
The axis shift estimation device, wherein the estimated value update unit includes a ratio proportion unit (4, S632) that increases the degree of contribution in proportion to the magnitude of the ratio of the estimation reliability to the output value reliability. An axis shift estimation device that estimates an axis shift angle of a radar device mounted on a moving object, comprising:
a first calculation unit (4, S40) that calculates a latest estimated value of the axis deviation angle based on target information that is information on a target detected by the radar device;
A second calculation unit (4, S50) for calculating an estimated reliability which is a reliability of the latest estimated value;
an estimate value update unit (4, S611 to S616, S621 to S624, S631 to S634) that updates an output estimate value that is a value output as a result of estimating the axis deviation angle, taking into account the latest estimate value;
Equipped with
the estimate value update unit is configured to increase a contribution degree of the latest estimate value to the output estimate value when the estimation reliability is a first reliability, compared to when the estimation reliability is a second reliability lower than the first reliability;
The axis shift estimation device, wherein the estimate value update unit includes a difference proportional unit (4, S622) that increases the degree of contribution in proportion to the magnitude of an absolute value of a difference between the output estimate value and the latest estimate value. 5. The axis shift estimation device according to claim 3, further comprising:
the estimate value updating unit increases the degree of contribution when an absolute value of a difference between the output estimate value and the latest estimate value is a first absolute value, compared to when the absolute value of the difference is a second absolute value smaller than the first absolute value. 6. The axis shift estimation device according to claim 4, further comprising:
The method further includes a reliability update unit (4, S617, S625, S635) that updates an output value reliability, which is a reliability of the output estimated value, by taking into account the estimation reliability,
The axis shift estimation device, wherein the estimated value update unit includes a ratio proportion unit (4, S632) that increases the degree of contribution in proportion to the magnitude of the ratio of the estimation reliability to the output value reliability. 7. The axis shift estimation device according to claim 2,
the first calculation unit calculates a cycle estimate that is an estimate of the axis deviation angle for each measurement cycle based on the target information for each predetermined measurement cycle, and smoothes a plurality of the cycle estimate values to calculate the latest estimate value. 8. The axis deviation estimation device according to claim 7,
The axis shift estimation device, wherein the estimation reliability is calculated as a value representing the smallness of variation among the plurality of cycle estimates. 9. The axis shift estimation device according to claim 1,
The estimation value update unit sets the contribution degree to 0 when the estimation reliability is equal to or less than a threshold value.

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