JP7136050B2 - Vehicle position estimation device - Google Patents

Description

The present invention relates to an own vehicle position estimation device that estimates the position of the own vehicle within the own lane, which is the lane in which the own vehicle is located during execution of automatic driving control.

BACKGROUND ART In recent years, research and development of automatic driving control for automatically driving a vehicle without the need for driving by a driver have been advanced. In the automatic driving control, first, the vehicle position in the own lane is estimated, and then the travel route is calculated and/or various vehicle controls are executed based on the estimated vehicle position. The estimation of the vehicle position within the own lane is performed after the absolute position estimation process of estimating the absolute position of the vehicle. That is, lane estimation processing is performed to estimate the own lane based on the absolute position estimated by the absolute position estimation processing, and then position estimation processing is performed to estimate the vehicle position based on the estimated own lane. , the vehicle position in the own lane is estimated.

Absolute position estimation processing is performed using, for example, information acquired using GNSS (Global Navigation Satellite System) including GPS, and sensors capable of detecting the momentum of the vehicle (wheel speed sensor and IMU etc.) is performed by so-called dead reckoning (see Patent Document 1). Note that IMU is an abbreviation for Inertial Measurement Unit, and is a device equipped with a sensor that detects angular velocity, acceleration, and the like in three dimensions.

JP 2018-155731 A

By performing the processes in the order described above, it is possible to estimate the vehicle position in the own lane while reducing the possibility of an increase in the computational load. However, depending on the driving environment of the vehicle, the estimation error due to the absolute position estimation process may increase, and in this case, the lane estimation process that should be executed subsequently may not be performed appropriately. For example, when the absolute position estimation process is performed by the dead reckoning described above, the estimation error increases due to the accumulation of the detection error of the momentum of the vehicle, and as a result, there is a possibility that the lane estimation process cannot be executed. be.

If the lane estimation process is not performed properly in this way, the position estimation process that should be executed later will not be performed properly (that is, the process will be stagnant on the way), so the vehicle in the own lane It becomes impossible to estimate the position appropriately, and there is a possibility that execution of automatic driving control becomes difficult.

The present invention has been made to address the problems discussed above. That is, one of the objects of the present invention is to provide a vehicle position estimation method that can appropriately estimate the vehicle position in the own lane even when the absolute position estimation error in the absolute position estimation process is relatively large. An object of the present invention is to provide an estimation device.

A self-vehicle position estimating device of the present invention (hereinafter also referred to as "present invention device") estimates the position of the self-vehicle in the self-lane, which is the lane in which the self-vehicle is located.
The device of the present invention is
absolute position estimating means (S205) for estimating the absolute position of the own vehicle;
imaging means (14) for imaging an area in front of the own vehicle including at least the road surface of the own lane;
map information acquisition means for acquiring map information (15a, 15b) including at least lane information that is information about lanes in which the vehicle can travel;
estimating the position of the own vehicle in the own lane based on the estimated absolute position, the captured image captured by the imaging means (14), and the acquired map information (15a, 15b); In-lane position estimation means for
Prepare.
The in-lane position estimation means includes:
If the estimated error of the absolute position by the absolute position estimating means is equal to or less than a predetermined error threshold (S210: Yes),
By estimating the own lane (S215) and then estimating the position of the own vehicle within a predetermined first range including the estimated own lane (S220), the position of the own vehicle within the own lane , and
If the estimated error exceeds the error threshold (S210: No),
By estimating the position of the own vehicle within a predetermined second range larger than the first range (S230), and then estimating the own lane based on the estimated position of the own vehicle (S235). estimating the position of the own vehicle in the own lane;
is configured as

In general, the process of estimating the own lane (lane estimation process) has a smaller computational load than the process of estimating the position of the own vehicle (position estimation process). Therefore, in the conventional vehicle position estimation device, after estimating the absolute position, the lane estimation process is first performed to narrow down the range in which the vehicle is located, and then the position estimation process is performed within the narrowed range. Therefore, the position of the own vehicle in the own lane is estimated while reducing the possibility of increasing the computational load. However, when the absolute position estimation error increases, the lane estimation processing may not be performed properly. (because the vehicle stops at a certain point), there is a possibility that the position of the own vehicle in the own lane cannot be estimated appropriately.

Therefore, the apparatus of the present invention adopts a configuration in which the order of subsequent processing is variable according to the estimated error of the absolute position. That is, when the estimation error of the absolute position is equal to or less than the error threshold (typically, when the estimation error is small enough to appropriately perform lane estimation processing), the lane estimation processing is first performed as in the conventional case, and then, Position estimation processing is performed within the range (first range) narrowed down by the processing. On the other hand, when the absolute position estimation error exceeds the error threshold (typically, when the estimation error is large enough to prevent lane estimation processing from being performed properly), the position estimation processing is performed first, and then the lane estimation processing is performed. I do. At this time, the position estimation process is performed within a second range that is larger than the first range. According to this configuration, even if the estimation error of the absolute position is relatively large, it is possible to appropriately estimate the position of the own vehicle in the own lane without stagnation in the middle of the process. Although the computational load increases as the position estimation process is performed within the second range, the position estimation process is performed within this range only when the absolute position estimation error exceeds the error threshold. The increase in load is kept to a minimum.

In the above description, in order to facilitate understanding of the invention, the reference numerals used in the embodiments are attached to the configurations of the invention corresponding to the embodiments in parentheses. are not limited to the embodiments defined by

1 is a schematic configuration diagram of a vehicle position estimation device according to an embodiment of the present invention; FIG. FIG. 2 is a flow chart showing a routine executed by a CPU of an ECU 10 shown in FIG. 1; FIG.

<Embodiment>
(Constitution)
An own vehicle position estimation device according to an embodiment of the present invention (hereinafter also referred to as "this embodiment device") is a vehicle capable of executing automatic driving control (hereinafter also referred to as "own vehicle" to distinguish it from other vehicles ). As shown in FIG. 1, the embodiment apparatus includes an own vehicle position estimation ECU 10 (hereinafter also simply referred to as "ECU 10").

ECU is an abbreviation for electronic control unit. The ECU 10 is an electronic control circuit including a microcomputer including CPU, ROM, RAM and the like. The CPU implements various functions described later by executing instructions (routines) stored in the ROM.

ECU 10 is connected with wheel speed sensor 11 , IMU 12 , GPS receiver 13 , camera sensor 14 and map database 15 . The ECU 10 acquires the signals and information acquired by these sensors and receivers 11 to 14 each time a predetermined time elapses. In addition, the ECU 10 acquires the map information stored in the map database 15 each time a predetermined period of time elapses.

The wheel speed sensor 11 is provided for each wheel (not shown) of the own vehicle. The wheel speed sensor 11 generates a pulse signal each time the corresponding wheel rotates by a predetermined angle.

The IMU 12 has an angular velocity sensor and an acceleration sensor. The angular velocity sensor measures three-axis angular velocity (roll angular velocity, pitch angular velocity, yaw angular velocity) of the own vehicle. The acceleration sensor measures three-axis acceleration (longitudinal acceleration, left-right acceleration, vertical acceleration) of the own vehicle. The "front-rear" direction represents the longitudinal axis direction of the vehicle, the "left-right" direction represents the width direction of the vehicle, and the "up-down" direction represents the height direction of the vehicle.

The GPS receiver 13 receives radio waves from GPS satellites.

The camera sensor 14 includes a camera section that captures a scene in front of the vehicle using visible light, and a data analysis section that analyzes image data captured by the camera section.
The data analysis unit recognizes road division lines (hereinafter also referred to as “white lines” for convenience) and lanes that are areas defined by the white lines, and recognizes the own lane (where the own vehicle is located) included in the image data. Information about the white lines such as the type of white lines (solid and dashed lines) on the left and right of the current lane), the distance between the white lines (lane width), and the shape of the white lines (for example, the curvature of the white lines) is acquired. Hereinafter, this information is also referred to as "camera own lane information".
In addition, the data analysis unit recognizes road markings and signboards installed near the road included in the image data, and acquires information about these road markings and signboards. Hereinafter, this information is also referred to as "camera target information".

The map database 15 includes a spatial information map 15a and a high precision spatial information map 15b. The spatial information map 15a includes information about white lines such as the types of white lines on the left and right sides of lanes in which the vehicle can travel, the distance between the white lines, and the shape of the white lines. Hereinafter, this information is also referred to as "map lane information". The high-precision spatial information map 15b contains more detailed information than the spatial information map 15a regarding roads and the environment near the roads. Specifically, the high-precision spatial information map 15b includes information on road markings and signboards installed near roads in addition to map lane information. Hereinafter, this information is also referred to as "map target information".

The ECU 10 executes absolute position estimation processing for estimating the absolute position of the own vehicle based on signals acquired from these sensors and receivers 11 to 13 . After that, the ECU 10 performs in-lane position estimation for estimating the position of the own vehicle (vehicle position) within the own lane based on the signals and information acquired from these sensors and receivers 11 to 14 and the map database 15. Execute the process. The in-lane position estimation process includes a lane estimation process of estimating the own lane and a position estimation process of estimating the position of the own vehicle within a predetermined range. The ECU 10 changes the order of executing the lane estimation process and the position estimation process according to the estimation error of the absolute position estimated by the absolute position estimation process. A specific description will be given below.

[Absolute position estimation process]
The ECU 10 calculates the speed of the vehicle (vehicle speed) based on the signal transmitted from the wheel speed sensor 11 . In addition, the ECU 10 acquires signals representing triaxial angular velocities and triaxial accelerations respectively measured by the angular velocity sensor and the acceleration sensor of the IMU 12 . Furthermore, the ECU 10 identifies the current position (latitude and longitude) of the vehicle based on GPS signals transmitted from the GPS receiver 13 .
The ECU 10 adds the momentum of the vehicle (vehicle speed, angular velocity, and acceleration) obtained from the wheel speed sensors 11 and the IMU 12 to the vehicle position specified based on the GPS signal (so-called dead reckoning). Estimate location.

[Lane estimation process]
The ECU 10 performs white line matching processing based on the camera own lane information acquired from the camera sensor 14 and the map lane information of the spatial information map 15 a acquired from the map database 15 . The white line matching process is a process of estimating a lane in which the types of white lines on the left and right of the own lane included in the camera's own lane information match the types of white lines included in the map lane information. The ECU 10 estimates the vehicle's own lane through white line matching processing. Note that the white line matching process may be performed based on the distance between the white lines and/or the shape of the white lines, in addition to the types of the white lines.

[Position estimation process]
Based on the camera own lane information and camera target information acquired from the camera sensor 14 and the map lane information and map target information contained in the high-precision spatial information map 15b acquired from the map database 15, the ECU 10 Matching processing for white lines and matching processing for road markings and signboards are performed. The white line matching process is as described above. The road marking and signboard matching process is a process of estimating a position where the road marking and signboard included in the camera target information match the road marking and signboard included in the map target information. The ECU 10 performs the white line matching process and the road marking/signboard matching process in parallel, thereby estimating the position of the vehicle on the high-precision spatial information map 15b in detail. As a result, the position of the own vehicle on the map 15b can be estimated with high accuracy.
Based on the absolute position estimation error in the absolute position estimation process, the ECU 10 performs the position estimation process in two ways: a first range that is relatively narrow and a second range that is relatively wide. Execute within range (details later).
Note that a coordinate system is set in advance in the high-precision spatial information map 15b, and the ECU 10 estimates the position of the vehicle using the coordinates. Therefore, the own lane is not estimated in the position estimation process.

In this embodiment, the absolute position is estimated by dead reckoning. Therefore, when the estimation error of the absolute position increases due to the accumulation of the detection error of the momentum of the vehicle, there is a possibility that the lane estimation process cannot be executed appropriately. Therefore, when the estimation error is equal to or less than a predetermined error threshold, the ECU 10 performs lane estimation processing and then position estimation processing, thereby performing in-lane position estimation processing (processing for estimating the position of the vehicle within the vehicle lane). However, on the other hand, if the estimation error exceeds the error threshold and therefore the lane estimation processing cannot be performed, the position estimation processing is performed first, and then the lane estimation processing is performed, thereby estimating the in-lane position Execute the process. That is, the ECU 10 changes (replaces) the order of the lane estimation process and the position estimation process according to the estimation error of the absolute position.

Here, the error threshold is an upper limit of an estimation error at which a normal (described later) lane estimation process can be appropriately performed, and can be calculated in advance by experiments or simulations. However, there are cases in which lane estimation processing is possible even if the estimation error exceeds the error threshold. In such a case, the ECU 10 first performs the lane estimation process and then the position estimation process, as in the case where the estimation error is equal to or less than the error threshold. Here, "when lane estimation processing is possible even if the estimation error exceeds the error threshold" means, for example, that the update of the camera sensor 14 allows the data analysis unit to detect not only the own lane but also the white lines of adjacent lanes. , information such as lane width and shape can be acquired, and lane estimation processing can be performed appropriately even if the estimated absolute position is relatively distant from the actual position of the vehicle. is the case. That is, the above-described "normal lane estimation processing" means lane estimation processing based on the performance of the ECU 10 at the time of initialization (before update).

More specifically, when the estimation error is equal to or less than the error threshold, or when the estimation error exceeds the error threshold but the lane estimation process is possible, the ECU 10 first executes the lane estimation process to estimate the own lane. By (identifying), the range in which the own vehicle may exist is narrowed down. Then, the position estimation process is executed within the range narrowed down by the process (that is, the range including at least the own lane; the first range).

The position estimation process is a process with a relatively high computational load, but according to this configuration, the position estimation process is executed within the range (first range) narrowed down by the lane estimation process, so the computational load increases. It is possible to estimate the position of the own vehicle in the own lane with high accuracy while reducing the possibility of

On the other hand, if the estimation error exceeds the error threshold and therefore the lane estimation process is impossible, the ECU 10 will set the estimated absolute position to a relatively wide range (i.e. The position of the vehicle on the high-precision spatial information map 15b is estimated by the coordinates by executing the position estimation process over a range that can include the actual position even if the position is changed (second range). Then, lane estimation processing is executed by performing white line matching processing based on the estimated coordinates.

In the conventional in-lane position estimation process, the order of executing the lane estimation process and the position estimation process is fixed in this order from the viewpoint of reducing the possibility of an increase in the computational load. For this reason, if the lane estimation process is not properly executed due to an absolute position estimation error due to the absolute position estimation process, the position estimation process that is supposed to be executed later cannot be performed. There was a possibility that the process would not be executed properly due to stagnation. However, according to the above configuration, when the estimation error of the absolute position exceeds the error threshold and the lane estimation process is impossible, the order of the lane estimation process and the position estimation process is changed (replaced). That is, the position estimation process is performed within the expanded second range, and then the lane estimation process is performed based on "the position of the own vehicle estimated by the position estimation process". Therefore, the in-lane position estimation process can be properly executed without stopping in the middle. Although the computational load increases when the position estimation process is executed within the second range compared to when it is executed within the first range, the position estimation process is executed within the second range due to the estimation error. Since it is limited to when the threshold value is exceeded, an increase in computational load is suppressed to a minimum.

The first range may be a predetermined range, or a range that changes according to the lane width of the own lane estimated by the lane estimation process (that is, a range that expands as the lane width increases). may be The second range may be a predetermined range, or may be a range that changes according to the estimation error of the absolute position (that is, a range that expands as the estimation error increases).

The "position of the own vehicle in the own lane" estimated by the ECU 10 is transmitted to other ECUs (not shown) that are connected so that data can be exchanged (communicated) via a communication/sensor system CAN (Controller Area Network). It is used when calculating the travel route and/or executing various other controls by automatic driving control.

(Specific action)
Next, specific operations of the ECU 10 will be described. The CPU of the ECU 10 executes the routine shown by the flow chart in FIG. 2 each time a predetermined period of time elapses.

At a predetermined timing, the CPU starts the in-lane position estimation processing from step 200 in FIG. Subsequently, the CPU proceeds to step 210 and determines whether or not the absolute position estimation error calculated in step 205 is equal to or less than the error threshold. If the determination is affirmative (S210: Yes), the CPU proceeds to step 215 and performs lane estimation processing for estimating the own lane by white line matching processing based on the camera's own lane information and map lane information. After that, the CPU proceeds to step 220, and in the first range narrowed down based on the processing of step 215, white line matching processing and road marking and signboard matching processing based on camera target information and map target information are performed. A position estimation process for estimating the position (coordinates) of the own vehicle in detail is performed by performing the above processes in parallel. As a result, the position of the own vehicle within the own lane can be estimated with high accuracy. After that, the CPU proceeds to step 295 and once terminates this routine.

On the other hand, if a negative determination is made in step 210 (S210: No), the CPU proceeds to step 225 and determines whether lane estimation processing is possible. If an affirmative determination is made (in other words, if the estimation error of the absolute position exceeds the error threshold, but the lane estimation process becomes possible due to an update of the camera sensor 14, etc. S225: Yes), the CPU The processing of steps 215 and 220 described above is performed in this order, and then the routine proceeds to step 295 to once end this routine.

On the other hand, if a negative determination is made in step 225 (in other words, if the absolute position estimation error exceeds the error threshold and therefore lane estimation processing is impossible; S225: No), the CPU Proceeding to step 230, position estimation processing for estimating the position of the host vehicle in detail within a second range that is larger than the first range is performed. Thereafter, the CPU proceeds to step S235, and performs lane estimation processing for estimating the own lane by performing white line matching processing based on the position (coordinates) of the own vehicle estimated by the processing of step S230. As a result, the position of the own vehicle within the own lane can be estimated with high accuracy. After that, the CPU proceeds to step 295 and once terminates this routine.

As described above, according to this embodiment, even when the absolute position estimation error in the absolute position estimation process is relatively large, the in-lane position estimation process can be executed appropriately. Appropriate estimation becomes possible.

When changing lanes using automated driving control (for example, merging into the main lane on a motorway, exiting to an exit, or changing lanes while driving), the position of the vehicle within its own lane can be estimated with high accuracy. requested. For this reason, this embodiment device is particularly useful when a lane change is performed by automatic driving control.

The present invention is not limited to the above embodiments, and various modifications are possible without departing from the object of the present invention.

For example, in the above embodiment, the vehicle position in the own lane estimated by the own vehicle position estimation device is used for calculating the travel route by automatic driving control, but the configuration is not limited to this. For example, the estimated vehicle position within the own lane may be used for calculation of a travel route by driving support control, or the like.

In addition, this embodiment device may be used when lane keeping is performed by automatic driving control or driving support control.

10: vehicle position estimation ECU, 11: wheel speed sensor, 12: IMU, 13: GPS receiver, 14: camera sensor, 15: map database, 15a: spatial information map, 15b: high precision spatial information map

Claims (1)

An own vehicle position estimation device for estimating the position of the own vehicle within the own lane, which is the lane in which the own vehicle is located,
absolute position estimation means for estimating the absolute position of the own vehicle;
imaging means for imaging an area in front of the own vehicle including at least the road surface of the own lane;
map information acquisition means for acquiring map information including at least lane information, which is information about lanes in which the vehicle can travel;
in-lane position estimation means for estimating the position of the vehicle within the own lane based on the estimated absolute position, the captured image captured by the imaging means, and the acquired map information;
with
The in-lane position estimation means includes:
when the estimation error of the absolute position by the absolute position estimating means is equal to or less than a predetermined error threshold,
estimating the own lane, and then estimating the position of the own vehicle within the own lane by estimating the position of the own vehicle within a predetermined first range including the estimated own lane;
if the estimated error exceeds the error threshold,
estimating the position of the own vehicle within a predetermined second range larger than the first range, and then estimating the own lane based on the estimated position of the own vehicle; estimating the position of the vehicle;
configured as
Self-vehicle position estimation device.

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