JP2020134460A - Gyro sensor correction system, gyro sensor correction method and processing device - Google Patents

Abstract

To provide a gyro sensor correction system that is applicable and high in versatility even while a vehicle is traveling in an environment where a GPS signal cannot be received.SOLUTION: A system includes: a GPS reception unit; a gyro sensor that outputs an amount of drift in a horizontal direction of a vehicle; a camera that shoots the periphery of the vehicle; a memory; and a processing device. The system has at least a first traveling state measurement mode, and a second traveling state measurement mode. The processing device is configured to: store a standard trajectory pattern acquired based on a trajectory of a characteristic point of an object shot by the camera when the vehicle is in a straight traveling state in the memory beforehand; when it is in the first traveling state measurement mode, compare a trajectory of a characteristic point of the object when the vehicle travels with the standard trajectory pattern, and thereby determine whether or not the vehicle is in the straight traveling state; when it is determined that the vehicle is in the straight traveling state, calculate an error value on the basis of the output of the gyro sensor at this point; and correct the gyro sensor on the basis of the error value.SELECTED DRAWING: Figure 2

Description

The present disclosure relates to a gyro sensor correction system, a gyro sensor correction method, and a processing device that can correct an accumulation error of a gyro sensor even while traveling in an environment where it is difficult to receive GPS signals.

The in-vehicle navigation system usually measures the absolute position of the vehicle with high accuracy based on the GPS signal, but the GPS signal cannot be received when the vehicle is traveling in a tunnel, a high-rise building area, a mountainous area, etc. or due to some abnormality. Sometimes, the position of the vehicle can be estimated based on the vehicle speed signal based on the output of the vehicle speed sensor, the magnitude and direction of acceleration based on the output of the acceleration sensor, and the magnitude and direction of the angular velocity based on the output of the gyro sensor. is there.

However, the gyro sensor is easily affected by temperature due to its structure, and even if it has high performance, a drift error (for example, 0.1 degree per 100 seconds) occurs with the passage of time. Therefore, it is necessary to correct the accumulation error of the gyro sensor (zero point correction, etc.) at a constant frequency (for example, every 20 minutes).

Therefore, as in Patent Document 1, the vehicle speed sensor detects the stationary state of the vehicle, the drift amount output by the gyro sensor when stopped is estimated as an error value, and the zero point correction of the gyro sensor is performed by subtracting the error value. The technology to do is proposed.

Further, as in Patent Document 2, there is a technique of calculating an error by comparing the amount of azimuth change obtained from the gyro sensor and the amount of azimuth change obtained from the GPS receiver, and correcting the gyro sensor.

Japanese Unexamined Patent Publication No. 64-3509 Japanese Unexamined Patent Publication No. 2000-55678

By the way, since Patent Document 1 cannot correct the zero point of the gyro sensor unless it is in a stationary state, it is not suitable for a case where the vehicle does not stop for a long time, for example, when traveling on a highway. Further, Patent Document 2 cannot be applied when traveling in a tunnel, in an environment where the reception environment is extremely poor such as a skyscraper town or a mountainous area, or in an environment where GPS signals cannot be received such as when an abnormality occurs in a GPS system. The present disclosure provides a highly versatile gyro sensor correction system, a gyro sensor correction method, and a processing device, which have been devised in view of the above-mentioned conventional circumstances and can be applied even while driving in an environment where GPS signals cannot be received. The purpose is to do.

The present disclosure is a system including a GPS receiver, a gyro sensor that outputs a horizontal drift amount of the vehicle, a camera that photographs the surroundings of the vehicle, a memory, and a processing device. The processing device has a running state measurement mode and a second running state measurement mode, and the processing device stores in advance a standard trajectory pattern acquired based on the trajectory of the feature point of the object taken by the camera when the vehicle is traveling straight. In the first traveling state measurement mode, it is determined whether or not the vehicle is in a straight-ahead state by comparing the trajectory of the feature point of the object when the vehicle is traveling with the standard trajectory pattern. Provided is a gyro sensor correction system that calculates an error value based on the output of the gyro sensor at that time and corrects the gyro sensor based on the error value when is determined to be in a straight running state.

Further, the present disclosure is a gyro sensor correction method in a system having a GPS receiving unit, a gyro sensor that outputs a drift amount in the horizontal direction of the vehicle, a camera that photographs the periphery of the vehicle, and a memory. The system has at least a first running state measurement mode and a second running state measurement mode, and preliminarily obtains a standard trajectory pattern acquired based on the trajectory of the feature point of the object taken by the camera when the vehicle is traveling straight. In the step of storing in the memory and in the first running state measurement mode, it is determined whether or not the vehicle is in a straight running state by comparing the locus of the feature point of the object when the vehicle is running and the standard locus pattern. The gyro has a step of calculating an error value based on the output of the gyro sensor at that time when the vehicle is determined to be in a straight-ahead state, and a step of correcting the gyro sensor based on the error value. A sensor correction method is provided.

Further, the present disclosure is a processing device for controlling a system having a GPS receiving unit, a gyro sensor that outputs the amount of drift in the horizontal direction of the vehicle, a camera that photographs the periphery of the vehicle, and a memory. The system has at least a first running state measurement mode and a second running state measurement mode, and the processing device acquires based on the locus of feature points of the object taken by the camera when the vehicle is traveling straight. The standard trajectory pattern is stored in the memory in advance, and in the first traveling state measurement mode, whether the vehicle is in a straight-ahead state by comparing the trajectory of the feature point of the object when the vehicle is traveling with the standard trajectory pattern. Provided is a processing device that determines whether or not, and when it is determined that the vehicle is traveling straight, calculates an error value based on the output of the gyro sensor at that time, and corrects the gyro sensor based on the error value. ..

It should be noted that any combination of the above components and the conversion of the expression of the present disclosure between methods, devices, systems, recording media, computer programs and the like are also effective as aspects of the present disclosure.

According to the present disclosure, the gyro sensor can be used even in a situation where the error correction process to be performed when the vehicle is stopped cannot be performed even when the vehicle is traveling in an environment where GPS signals cannot be received, or when the vehicle is continuously traveling for a long time such as when traveling on a highway. We will realize a highly versatile gyro sensor correction system, gyro sensor correction method, and processing device that enable correction.

Block diagram of the gyro sensor correction system in the present disclosure Flow chart showing an example of the gyro sensor correction method in the present disclosure Flowchart showing an example of steps to generate a standard trajectory pattern Schematic diagram showing the environment behind the vehicle in different driving states of the vehicle Schematic diagram showing the trajectory of a road sign in a straight-ahead state Schematic diagram showing changes in the white line when a vehicle travels on different positions on the road Schematic diagram showing the trajectory of the white line when the vehicle is curved Schematic diagram showing the relationship between angle change and time in different driving states of a vehicle Schematic diagram for explaining a preferred embodiment of a gyro sensor correction system

Hereinafter, embodiments in which the gyro sensor correction system, the gyro sensor correction method, and the processing device according to the present disclosure are specifically disclosed will be described in detail with reference to the accompanying drawings as appropriate. However, more detailed explanation than necessary may be omitted. For example, detailed explanations of already well-known matters and duplicate explanations for substantially the same configuration may be omitted. This is to avoid unnecessary redundancy of the following description and to facilitate the understanding of those skilled in the art. It should be noted that the accompanying drawings and the following description are provided for those skilled in the art to fully understand the present disclosure, and are not intended to limit the subject matter described in the claims.

The gyro sensor correction system in the present disclosure is a system for correcting an error of a gyro sensor mounted on a vehicle. In the following, it will be described as a system mounted on an automobile for convenience, but it may be applied to any other vehicle such as a truck, a bus, or a motorcycle. Hereinafter, for convenience of explanation, the same means will be described with the same reference numerals in the drawings.

FIG. 1 is a block diagram of the gyro sensor correction system in the present disclosure. As shown in FIG. 1, the gyro sensor correction system 100 in the present embodiment includes, but is not limited to, at least a processing device 101, a GPS receiving unit 102, a gyro sensor 103, a camera 104, and a memory 105. Any other means such as an acceleration sensor, a geomagnetic orientation sensor, a display device, etc. may be included.

The processing device 101 is, for example, a processor or the like, and performs various controls by performing calculations. The processing device 101 may constitute the processing device in the present disclosure. Further, the process (step) executed by the processing device 101 may constitute the gyro sensor correction method in the present disclosure. The specific content of the process will be described later. In the present disclosure, the processing device 101 will be described as one means for convenience of explanation, but the present disclosure is not necessarily realized by one processor physically, and each processor of each means jointly describes the processing device 101. May be configured. Further, the central processing unit (CPU) and the processing unit of each device may cooperate to perform processing.

The GPS receiving unit 102 receives signals (time, orbit information) from a plurality of GPS satellites in orbit on the earth, calculates the time difference and the arrival speed of radio waves, and determines the distance from the satellites. By specifying the latitude and longitude based on that, the absolute position information of the vehicle is acquired. In addition, the gyro sensor correction system can also acquire the bearing and speed of the vehicle based on the change in the absolute position information obtained from the GPS receiving unit 102. The specific configuration of the GPS receiving unit 102 in the present disclosure may be a conventional one, and detailed description thereof will be omitted here. Although the GPS receiving unit 102 is described here as a part of the gyro sensor correction system, the GPS receiving unit 102 actually constitutes a part of the vehicle navigation system, and the navigation system can communicate with the gyro sensor correction system. It may be a configuration.

The gyro sensor 103 measures an angular velocity (angle / s) indicating the amount of rotation per unit time. The angular velocity includes yaw, pitch, and roll depending on the measurement direction, but in the present disclosure, the amount of drift in the horizontal direction (that is, the left-right direction on a plane) of the vehicle is output by detecting at least the angular velocity of yaw. .. Here, the drift amount is, for example, a yaw angle displacement amount that indicates the horizontal turning behavior (yaw) of the vehicle. The specific structure of the gyro sensor 103 may be any conventional structure, and detailed description thereof will be omitted here.

The camera 104 images the periphery of the vehicle. The camera 104 preferably captures the rear of the vehicle, which is the easiest to determine the traveling locus of the vehicle, but is capable of photographing an object that can determine the straight-ahead state of the vehicle based on the locus of the feature points when the vehicle is traveling. If so, other directions such as the front or left and right of the vehicle may be photographed. The camera 104 may be, for example, a back camera provided for displaying the rear situation on the display when the vehicle is backed up, or may be an individual camera attached later. However, when the back camera of the vehicle is used as the camera 104, it is not necessary to display the captured image on the display. Further, it is preferable that the camera 104 is provided with a lens having an angle of view capable of tracking the movement of an object around the vehicle as the vehicle travels (for example, a white line having a length of 2 to 3 m). The specific structure of the camera 104 itself may be any conventional one, and detailed description thereof will be omitted here.

The memory 105 may be any computer-readable recording medium, for example, SRAM (Static Random Access Memory), DRAM (Dynamic Random Access Memory), EEPROM (Erasable Programmable Read Only Memory), EEPROM (Electrically Erasable Programmable Read-Only Memory). , And at least one of a flash memory such as a USB memory. The memory 105 may include a memory in a narrow sense for tentatively storing data processed by the processing device 101 for calculation, and a storage for recording data acquired by each means. Further, although the memory 105 is conceptually described as one means for convenience of explanation, it does not have to be physically one means, for example, each means has its own memory. These may jointly form the memory 105.

Next, various processes (steps) of the processing device 101 in the gyro sensor correction system 100 will be described in detail with reference to FIG. In addition, each step described below may constitute the gyro sensor correction method in this disclosure.

First, the processing device 101 stores in advance the standard trajectory pattern acquired based on the trajectory of the feature points of the object captured by the camera 104 when the vehicle is traveling straight (step S10). The "object" here means a subject within the shooting range of the camera, such as the center line, side line, bicycle road separation line, guardrail, step, wall, sign, utility pole, etc. marked on the road. Can be mentioned. The "feature point" may be any element for identifying the above-mentioned object, and includes, for example, information on the shape, color, pattern, etc. of the whole or a part of the object.

Taking the camera 104 that captures the rear of the vehicle as an example, if the vehicle is in a straight-ahead state, an image as shown in FIG. 4A can be acquired, for example. At this time, the three objects of the white line L1, the white line L2, and the guardrail G extend linearly. On the other hand, if the vehicle is in a curved state, the white line L1, the white line L2, and the guardrail G are all curved as shown in FIG. 4B, for example. In step S10, a standard locus pattern that serves as a “measure” for determining straight ahead in the future is acquired and stored in the memory 105 in advance. The standard locus pattern is preferably a locus of feature points of an object photographed in a state where the straight-ahead state of the vehicle can be accurately confirmed by GPS signals, map information of the vehicle navigation system, or the like.

The number of objects is not limited to one, and a plurality of objects may exist as shown in FIGS. 4A and 4B. When there are a plurality of objects, the processing device 101 may store the standard locus pattern of each object in the memory 105. At this time, the timing of acquiring and recording the standard trajectory pattern applied to each object may be different. For example, when the guardrail G appears in the middle of traveling, the processing device 101 may acquire the standard trajectory pattern of the guardrail G at the timing when the guardrail G appears and store it in the memory 105.

As described above, in particular, a linear sign or an object extending along the traveling direction of a vehicle such as a line, a guard rail, or a wall is an object in the present disclosure because the traveling locus of the vehicle can be recognized from a single still image. Is suitable as. On the other hand, when the object is a single object such as a road sign, a plurality of continuous images may be acquired at different timings to calculate the trajectory of the object. For example, the camera 104 acquires the image of FIG. 5 (A) at the timing of t1, the image of FIG. 5 (B) at the timing of t2 thereafter, and the image of FIG. 5 (C) at the timing of t3 thereafter. Is obtained. Since the vehicle is traveling straight, the road signs taken at the above three timings from the camera behind the vehicle move away in the order of sign S (t1), sign S (t2), and sign S (t3). By tracking the positions of the signs at different timings, it is possible to calculate the trajectory of the sign S as the vehicle travels. Then, the processing device 101 may store the locus of the sign S in the straight-ahead state in the memory 105 in step S10.

The gyro sensor correction system in the present disclosure has a first running state measurement mode for measuring the straight running state of the vehicle based on the standard trajectory pattern stored in the memory 105 in step S10, and a second running state other than that. It has a measurement mode.

In the first traveling state measurement mode, the processing device 101 determines whether or not the vehicle is in a straight-ahead state by comparing the locus of feature points of an object during traveling of the vehicle with a standard locus pattern. Specifically, the processing device 101 measures the locus of the feature points of the object captured by the camera 104, reads out the standard locus pattern stored in step S10 from the memory 105, and has a parallel relationship between the two. Judge whether or not. Here, the judgment standard is set to "parallel" instead of "match" because, as shown in FIG. 6 (A), the vehicle at the t (standard) timing at the time of generating the standard trajectory pattern even in the same straight running state. This is because the position of the vehicle and the position of the vehicle at the timing of t (measurement) at the time of measuring the traveling state do not always match the object. As shown in FIG. 6B, when the white line L1 and the white line L2 obtained when measuring the traveling state are in a parallel relationship with the standard L1 and the standard L2 in the standard locus pattern, the processing device 101 is concerned. Judge that the vehicle is going straight.

On the other hand, as shown in FIG. 7A, the vehicle may be curved when measuring the traveling state. At this time, the white line L1 and the white line L2 obtained when measuring the traveling state as shown in FIG. 7B have a constant angle with the standard L1 and the standard L2 and are not parallel to each other. Determines that the vehicle is not in a straight running state.

Note that "parallel" in the present disclosure does not have to be strict parallel, and includes cases where the angle is fine. Further, as shown in FIG. 8A, the processing device 101 compares the locus of feature points of objects around the vehicle while traveling with a standard locus pattern, and obtains a predetermined time t of an angle change Δ. When the average value within (for example, 10 seconds; the same applies hereinafter) is within a predetermined threshold value, it may be determined that the vehicle is in a straight-ahead state. The average value can be calculated by integrating, for example, the angle change Δ at a predetermined time t. As a result, it is possible to prevent the vehicle from being unable to accurately determine the straight-ahead state due to accidental blurring of the vehicle.

On the other hand, as shown in FIG. 8B, the average value of the angle change Δ obtained by comparing the locus of the feature points of the surrounding objects when the vehicle is running and the standard locus pattern within a predetermined time t. If exceeds a certain threshold value, the processing device 101 determines that the vehicle is not in a straight-ahead state. At this time, it is preferable that the processing device 101 outputs information indicating the traveling direction of the vehicle to the navigation system of the vehicle. As shown in FIG. 9, when the vehicle travels in the gentle Y-branch direction D1, the amount of drift in the horizontal direction is below the threshold value that can be identified by the gyro sensor, so that the navigation system is traveling straight in the direction of D2. May be misunderstood. Such an error can be overcome by the processing device 101 outputting information indicating the traveling direction of the vehicle to the navigation system.

The second running state measurement mode measures the straight running state of the vehicle based on a reliable conventional determination method using GPS signals. As an example of the second driving state measurement mode, when the map information of the navigation system mounted on the vehicle is read out and it is recognized that the vehicle is running on a straight road based on the GPS signal, the vehicle is going straight. to decide. As another example of the second traveling state measurement mode, the straight running state of the vehicle is measured based on the azimuth information of the GPS signal received by the GPS receiving unit 102. Then, the processing device 101 can measure the traveling state of the vehicle more accurately by combining the above two examples.

More preferably, as shown in FIG. 2, the processing device 101 monitors the reception status of the GPS signal by the GPS receiving unit 102, and when the GPS receiving unit 102 cannot receive the GPS signal for a certain period of time (for example, 20 minutes) or more. (Step S20, "YES") is set to the first running state measurement mode (step S30), and when GPS signals can be received (step S20, "NO"), the second running state measurement mode is set (step S20). S40).

If the processing device 101 determines that the vehicle is not in a straight-ahead state (step S50, "NO") by the first traveling state measurement mode or the second traveling state measurement mode, the process returns to step S20 and is based on the GPS signal reception status. Reselect the driving condition measurement mode.

On the other hand, when the processing device 101 determines that the vehicle is in a straight-ahead state in the first running state measurement mode or the second running state measurement mode, an error value is calculated based on the output of the gyro sensor 103 at that time. Then, the gyro sensor 103 is corrected based on the error value. For example, when the vehicle is traveling straight, the output voltage of the gyro sensor 103 indicating the draft amount in the horizontal direction should be originally zero. Therefore, if the output voltage at that time is detected, the processing device 101 will perform. The gyro sensor 103 can be corrected by storing it in the memory 105 as an error value and then subtracting the error value from the output voltage of the gyro sensor 103.

Through the above series of processes, even while driving in an environment where GPS signals cannot be received, the straight-ahead state of the vehicle is determined by comparing the trajectory of the object around the vehicle photographed by the camera 104 with the standard trajectory pattern. Then, the error value can be calculated to correct the gyro sensor.

In the gyro sensor correction system 100 of the present disclosure, the standard locus pattern is used to determine the straight running state of the vehicle by comparing the locus of the feature points of the object when measuring the running state of the vehicle with the standard locus pattern stored in advance. The accuracy of is essential. Therefore, the present disclosure provides an example for generating a highly reliable standard locus pattern as shown in FIG.

First, the first locus of the feature points of the object photographed when the vehicle is determined to be in the straight-ahead state based on the second traveling state measurement mode is stored in the memory 105 (step S11). Since the second traveling state measurement mode is a highly reliable measurement mode based on GPS signals, the accuracy of the first trajectory is guaranteed.

Then, after a predetermined time, the second locus of the feature points of the object photographed when the vehicle goes straight based on the second traveling state measurement mode is calculated (step S12), and is stored in the memory 105. Compare with 1 locus. At this time, since the second locus is also acquired based on the highly reliable second traveling state measurement mode, the accuracy is guaranteed.

Then, when the first locus and the second locus are parallel (step S13, “YES”), the first locus or the second locus is stored as a standard locus pattern. On the other hand, when the first locus and the second locus are not parallel (step S13, "NO"), the process returns to step S11 and is acquired from the first locus again. Thereby, the reliability of the gyro sensor correction system in the present disclosure can be significantly improved.

Although the present disclosure has been described above using the embodiments, the technical scope of the invention according to the present disclosure is not limited to the scope described in the above-described embodiments. It will be apparent to those skilled in the art to make various changes or improvements to the embodiments described above. It is clear from the description of the claims that the form with such changes or improvements may be included in the technical scope of the present invention.

The execution order of each process such as operation, procedure, step, and step in the device, system, program, and method shown in the claims, the specification, and the drawings is particularly "before" and "prior to". As long as the output of the previous process is not used in the subsequent process, it can be realized in any order. Even if the scope of claims, the specification, and the operation flow in the drawings are explained using "first", "next", etc. for convenience, it does not mean that it is essential to carry out in this order. Absent.

The present disclosure is useful as a highly versatile gyro sensor correction system that can be applied even while traveling in an environment where GPS signals cannot be received.

100 Gyro sensor correction system 101 Processing device 102 GPS receiver 103 Gyro sensor 104 Camera 105 Memory

Claims (10)

GPS receiver and
A gyro sensor that outputs the amount of drift in the horizontal direction of the vehicle,
A camera that captures the surroundings of the vehicle
With memory
In a system with a processing device
The system has at least a first running state measurement mode and a second running state measurement mode.
The processing device is
A standard locus pattern acquired based on the locus of feature points of an object taken by the camera when the vehicle is traveling straight is stored in the memory in advance.
In the first traveling state measurement mode, whether or not the vehicle is in a straight-ahead state is determined by comparing the trajectory of the feature point of the object captured by the camera while the vehicle is traveling with the standard trajectory pattern. Judge,
A gyro sensor correction system that calculates an error value based on the output of the gyro sensor at that time when the vehicle is determined to be in a straight-ahead state, and corrects the gyro sensor based on the error value. The processing device is
In the second driving state measurement mode, whether or not the vehicle is in a straight-ahead state is determined based on at least one of the map information of the navigation system mounted on the vehicle and the azimuth information of the GPS signal. The gyro sensor correction system according to claim 1. The second aspect of the present invention is that the processing device is set to the second running state measurement mode when a GPS signal can be received, and is set to the first running state measurement mode when the GPS signal cannot be received for a predetermined time. Described gyro sensor correction system. The gyro sensor correction system according to any one of claims 1 to 3, wherein the camera captures the rear of the vehicle. The gyro sensor correction system according to any one of claims 1 to 4, wherein the object is at least one linear sign or object extending along the traveling direction of the vehicle. The processing device is
Based on the second traveling state measurement mode, the first locus of the feature points of the object taken when the vehicle is determined to be in the straight-ahead state is stored in the memory.
After a predetermined time, the second locus of the feature point of the object photographed when the vehicle goes straight based on the second traveling state measurement mode is calculated.
The gyro sensor correction according to any one of claims 2 to 5, wherein when the first locus and the second locus are parallel, the first locus or the second locus is stored as the standard locus pattern. system. When the average value of the angle change within a predetermined time obtained by comparing the locus of feature points of an object around the vehicle while traveling and the standard locus pattern is within a predetermined threshold value, the vehicle The gyro sensor correction system according to any one of claims 1 to 6, which determines that the vehicle is in a straight-ahead state. When the average value of the angle change within a predetermined time obtained by comparing the locus of feature points of an object around the vehicle while traveling and the standard locus pattern exceeds a predetermined threshold value, the vehicle advances. The gyro sensor correction system according to any one of claims 1 to 7, which outputs information indicating a direction to the navigation system of the vehicle. A gyro sensor correction method in a system having a GPS receiver, a gyro sensor that outputs the amount of drift in the horizontal direction of the vehicle, a camera that photographs the surroundings of the vehicle, and a memory.
The system has at least a first running state measurement mode and a second running state measurement mode.
A step of storing in advance a standard trajectory pattern acquired based on the trajectory of a feature point of an object taken by the camera when the vehicle is traveling straight, and a step of storing the standard trajectory pattern in the memory in advance.
In the first traveling state measurement mode, a step of determining whether or not the vehicle is in a straight-ahead state by comparing the trajectory of a feature point of the object during traveling of the vehicle with the standard trajectory pattern, and
A gyro sensor having a step of calculating an error value based on the output of the gyro sensor at that time when the vehicle is determined to be in a straight-ahead state and correcting the gyro sensor based on the error value. Correction method. A processing device for controlling a system having a GPS receiving unit, a gyro sensor that outputs the amount of drift in the horizontal direction of the vehicle, a camera that photographs the surroundings of the vehicle, and a memory.
The system has at least a first running state measurement mode and a second running state measurement mode.
The processing device is
The standard trajectory pattern acquired based on the trajectory of the feature point of the object captured by the camera when the vehicle is traveling straight is stored in the memory in advance.
In the first traveling state measurement mode, it is determined whether or not the vehicle is in a straight-ahead state by comparing the locus of the feature points of the object during traveling of the vehicle with the standard locus pattern.
A processing device that calculates an error value based on the output of the gyro sensor at that time when the vehicle is determined to be in a straight-ahead state, and corrects the gyro sensor based on the error value.

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