KR102144222B1 - Clothoid parking path generation method and apparatus using a towing point - Google Patents

Abstract

The present invention discloses a clothoid parking path generation method and device using a towing point. According to the present invention, the parking path generation device for autonomous parking comprises: a processor; and a memory connected to the processor. The memory stores program instructions, which may be executed by the processor, to receive a parking space image through a camera, set a towing point and a parking completion point on a parking space coordinate system using the parking space image, generate a clothoid curve from an initial pose of a vehicle to the set towing point, update a rate of a change of curvature of the clothoid curve according to movement of the vehicle and generate a clothoid parking path while moving the towing point in a direction of the parking completion point when the vehicle approaches the set towing point.

Description

Clothoid parking path generation method and apparatus using a towing point}

The present invention relates to a method and apparatus for generating a clothoid parking route using a towing point.

Traffic accidents frequently occur due to the driver's carelessness, poor visibility, and violation of the duty to look forward to the vehicle behind the vehicle.

To prevent this, vehicles are recently equipped with Advanced Driver Assistance Systems (ADAS).

The intelligent driver assistance system uses advanced detection sensors, GPS, communication, and intelligent video equipment to recognize some situations while driving by itself to determine the situation, control the car, or make sound and light so that the driver can detect danger in advance. It is a driver assistance system that informs you by vibration, etc.

Among the driver assistance systems, the Smart Parking Assistant System (SPAS) provides convenience to the driver when parking a vehicle and prevents contact accidents caused by leaving the parking space to drivers who are inexperienced in parking.

Recently, a service that supports autonomous parking using cameras and sensors installed around the vehicle is also provided.

Conventional parking assistance systems (SPAS) detect obstacles using sensors such as ultrasonic waves with limited sensing distance and direction to find a part of the parking space, and if the driver wants to park in the parking space, the vehicle can enter the parking space. To be able to do so, a parking path consisting of a combination of an arc and a straight line is created, and steering is obtained directly from the parking path to control the steering angle of the vehicle.

At this time, the connecting part of the arc and the straight line has a discontinuous curvature, and in order to implement such a planned path, the steering is very fast at the discontinuity point and the vehicle speed must be negligibly small, thus creating a fairly unnatural path.

Korean Patent Registration No. 10-0974704

In order to solve the problems of the prior art described above, the present invention is to propose a method and apparatus for generating a clothoid parking path using a towing point that can be well followed by a vehicle.

In order to achieve the above object, according to an embodiment of the present invention, an apparatus for generating a parking route for autonomous parking, comprising: a processor; And a memory connected to the processor, wherein the memory receives a parking space image through a camera, sets a towing point and a parking completion point on a parking space coordinate system using the parking space image, and at the initial pose of the vehicle Generate a clothoid curve up to the set towing point, update the rate of change of curvature of the clothoid curve according to the movement of the vehicle, and when the vehicle approaches the set towing point, the towing point is parked There is provided a parking route generating apparatus storing program instructions executable by the processor so as to generate a clothoid parking route while moving in the direction of a completion point.

The parking space coordinate system is defined by x, y, and a heading angle, and the towing point may be set to have a y coordinate and a heading angle similar to the parking completion point.

When the reference point of the vehicle is located within a preset distance from the set towing point, the program instructions may generate the closesoid parking path while moving the towing point in the x coordinate direction of the parking completion point.

The reference point of the vehicle may be set as x, y and a heading angle of the center of the rear wheel axis of the vehicle on the vehicle coordinate system.

The program instructions may move the towing point in the direction of the parking completion point based on the speed of the vehicle.

The clothoid curve is defined by the following formula,

[Equation]

The program instructions determine the distance between the reference point of the vehicle and the set towing point according to the movement of the vehicle, the distance between the reference point of the vehicle and the set towing point, the y coordinate and the heading angle of the set towing point. Each coefficient of the clothoid curve can be calculated using.

According to another aspect of the present invention, there is provided a method for generating a parking path for autonomous parking, comprising: (a) receiving an image of a parking space through a camera; (b) setting a towing point and a parking completion point on a parking space coordinate system using the parking space image; (c) generating a clothoid curve from the initial pose of the vehicle to the set towing point; (d) updating a rate of change of curvature of the clothoid curve according to the movement of the vehicle; And (e) when the vehicle is close to the set towing point, moving the towing point in the direction of the parking completion point and generating a closed parking route.

According to another aspect of the present invention, a program recorded on a recording medium for performing the above method is provided.

According to the present invention, since a clothoid parking path is generated using a towing point, autonomous parking can be smoothly performed and comfort can be provided to the driver.

1 is a view showing the configuration of a parking route generating apparatus according to an embodiment of the present invention.
2 is a diagram showing a vehicle and a parking space coordinate system according to the present embodiment.
3 is a view showing a clothoid parking route according to an embodiment of the present invention.
4 is a view showing a process of initial parking, just before moving to the towing point, moving to the towing point, and until parking is completed according to an embodiment of the present invention.
5 is a flowchart illustrating a process of generating a closed parking path for autonomous parking according to an exemplary embodiment of the present invention.

In the present invention, various modifications may be made and various embodiments may be provided, and specific embodiments will be illustrated in the drawings and described in detail.

However, this is not intended to limit the present invention to a specific embodiment, it is to be understood as including all changes, equivalents, and substitutes included in the spirit and scope of the present invention.

The present invention creates a clothoid parking route for autonomous parking.

The clothoid curve means a curve having a continuous and gradually changing curvature rate of change, and is generally applied to road construction for smooth driving of a vehicle.

Applying the clothoid curve to the parking path creation enables smooth steering and vehicle movement without discontinuous curvature, enabling very comfortable parking control for the driver.

1 is a view showing the configuration of a parking route generating apparatus according to an embodiment of the present invention.

As shown in FIG. 1, the apparatus for generating a parking route according to the present embodiment may include a processor 100 and a memory 102.

The processor 100 may include a central processing unit (CPU) capable of executing a computer program or a virtual machine.

The memory 102 may include a nonvolatile storage device such as a fixed hard drive or a removable storage device. The removable storage device may include a compact flash unit, a USB memory stick, or the like. Memory 102 may also include volatile memories such as various random access memories.

Program instructions executable by the processor 100 are stored in the memory 102.

The apparatus for generating a parking route according to the present embodiment is a computing device installed in a vehicle, and generates a parking route so that the vehicle can autonomously park in a parking space using a parking space image input through a camera.

In more detail, the program instructions according to this embodiment receive a parking space image through a camera, use the parking space image to set a towing point and a parking completion point on the parking space coordinate system, and the initial vehicle Create a clothoid curve from the pose to the towing point, update the rate of change of curvature of the clothoid curve according to the movement of the vehicle, and move the towing point toward the parking completion point when the vehicle approaches the set towing point. While creating a clothoid parking route.

The parking space image may be an image obtained by converting an image captured from a front or rear camera of the vehicle into a top view.

Hereinafter, a coordinate system for generating a parking route, a vehicle, a towing point, a parking completion point, and a parking route generation process according to the present embodiment will be described in detail with reference to the drawings.

In the present specification, the coordinates of the vehicle, the towing point, and the parking completion point are defined as a pose, and the pose means the coordinates of a predetermined reference point of the vehicle in the vehicle coordinate system, the coordinates of the towing point coordinates, and the parking completion point in the parking space coordinate system.

2 is a diagram showing a vehicle and a parking space coordinate system according to the present embodiment.

상 목적물의 포즈를

로 표시한다. 2, arbitrary coordinate system

The pose of the target object

Denoted by

평면상에 존재할 때, 목적물의 포즈는 목적물의 지정된 특징점의 좌표계 상의 위치

와 목적물이

좌표축과 이루는 헤딩각

로 표시한다. Target

When present on the plane, the pose of the object is the position on the coordinate system of the specified feature point of the object.

And the object

Heading angle with coordinate axis

Denoted by

The parking completion point is located in the parking space, and the center of the rear axle (hereinafter referred to as CRA) of the vehicle is located when parking is completed with respect to the parking space.

In the present invention, a parking completion point of a parking space is set as a feature point (reference point), and a pose for the parking completion point is defined as a pose of the parking space.

로 표시한다. The parking completion point of the parking space is

Denoted by

로 표시한다. The vehicle's feature point (reference point) is set as CRA, and the pose for the CRA is defined as the vehicle's pose,

Denoted by

는 주차 완료점을 원점으로 하고 주차공간에 고정된 좌표계로 정의한다. Parking space coordinate system

Is defined as the coordinate system fixed in the parking space with the parking completion point as the origin.

는 차량의 CRA를 원점으로 하고 차량에 고정된 좌표계로 정의한다. Vehicle coordinate system

Is defined as the vehicle's CRA as the origin and a fixed coordinate system on the vehicle.

When the origin of the vehicle coordinate system and the location of the sensor installed in the vehicle are different, the sensor value is transformed from the sensor coordinate system and displayed in the vehicle coordinate system.

평면에 주차공간이 존재하고,

평면에 차량이 존재하는 것으로 가정한다. For convenience

There is a parking space on the plane,

It is assumed that there is a vehicle on the plane.

이고, 차량 좌표계는

로 표시한다. As shown in Figure 2, the parking space coordinate system determined in the present invention is

And the vehicle coordinate system is

Denoted by

에 해당하는 주차공간 좌표계의 원점이다. Parking completion point

It is the origin of the parking space coordinate system corresponding to.

로 표시한다. The vehicle's pose is the center of the rear wheel axis (CRA) as the parking space coordinate system.

Denoted by

로 표시한다. The pose of the towing point is in the parking space coordinate system.

Denoted by

로 표시한다. The pose of the parking space in the vehicle coordinate system

Denoted by

로 표시한다. The pose of the obstacle in the vehicle coordinate system

Denoted by

, 그 시간 미분을

라 하고, 상태 변수를

라 하고 차량에 가하는 가속도 명령을

라 할 때 아래와 같다. Vehicle speed-acceleration modeling in such a coordinate system

, That time derivative

And the state variable

And give the acceleration command to the vehicle

Is as follows.

는 time constant,

,

이다. here,

Is the time constant,

,

to be.

라 하고

의 순차 값으로 시간

이라 할 때 이산화 모델식은 다음과 같다. Sampling cycle

La and

Time as a sequential value of

In this case, the discrete model equation is as follows.

,

이다.here,

,

to be.

로 표시할 때 종횡 모션 모델링은 다음과 같다. Vehicle pose

When expressed as, the vertical and horizontal motion modeling is as follows.

The formula for the Forward-Euler discrete model in the parking space coordinate system is as follows.

이다. here,

to be.

Hereinafter, a process of generating a closed parking path through the coordinate system and vehicle speed-acceleration modeling will be described in detail.

The clothoid pathway is a curve subject to a continuously slowly changing curvature.

The curvature along the arc is expressed as follows.

If the arc change is not severe, the continuous curvature condition can be applied to the straight line distance as follows.

Integrating this twice gives the closesoid parking path equation as shown below.

In creating a parking route, a curved shape and a straight line or a shape close to a straight line are required differently for each area outside and inside the parking space.

In order to park, the parking space has a straight parking path with a curvature of zero passing through the parking space, and before entering the parking space, the curve has a curvature to enter the center of the parking space at the right angle while touching the vehicle's pose. Should be.

As such, the parking path has a discontinuous curvature between before entering the parking space and inside the parking space. In this situation, since the curvature rate is also different, it is not possible to display a clothoid curve between the vehicle pose before entering the parking space and the parking completion point. That is, a parking path with a discontinuous curvature (the rate of change of curvature is not constant) does not meet the closesoid condition.

FIG. 3 is a diagram showing a clothoid parking route according to an embodiment of the present invention, and FIG. 4 is a process of initial parking, just before moving to the towing point, moving to the towing point, and completing parking according to an embodiment of the present invention. It is a diagram showing.

As shown in Figs. 3 to 4, the present invention creates a closed path with a constant curvature change rate only for some sections necessary for tracking the parking path of the vehicle in creating the parking path, and changes the pose according to the path tracking of the vehicle. According to the update rate of change of curvature, the closoid parking path is updated.

The present invention sets a towing point that moves in the direction of the parking completion point according to the transformation of the vehicle's pose between the parking completion point and the vehicle's pose in order to generate and update the clothoid curve, and from the pose of the towing point to the pose of the vehicle Create a clothoid parking route.

에 설정하는 토잉점(towing point)

까지의 주차공간 진입에 적합한 클로소이드 경로를 생성한다.In the present invention, in order to generate a clothoid curve, in the pose of a vehicle capable of generating a clothoid curve as follows,

Towing point

Create a clothoid path suitable for entering the parking space to.

에서 토잉점과의 거리 차이인

를 계산한다. Initial position of the vehicle

Is the difference between the towing point and

To calculate.

초기값을 구한다. As shown below, in the initial pose of the vehicle

Find the initial value.

를 구하고

를 클로소이드 조건이 만족되도록 정한다. When the vehicle is moving, depending on the vehicle's pose change

To get

Is determined so that the clothoid condition is satisfied.

는

의 변화를 클로소이드 조건에 맞게 정하는 설계변수이다. here,

Is

It is a design variable that determines the change of in accordance with the clothoid condition.

와

는 토잉점 포즈

로부터

와 같이 바로 구할 수 있다. Coefficient

Wow

The toe point pose

from

You can get it right away.

가

또는

이 되도록

축상에 위치하게 되면 차량을 주차공간 중심에 위치와 각도가 맞게 토잉하는 바람직한 의미가 있다. Toying store

end

or

To be

If it is located on the shaft, it has a desirable meaning of towing the vehicle to the center of the parking space with the correct position and angle.

For an arbitrary toe point pose and a pose of a given vehicle

관계를 이용하여

를 계산한다.

Using relationships

To calculate.

에 가까이 오게되면 점차

의 값도 작아지고 헤딩각

도 작아지게 된다. The vehicle is towing point along the clothoid parking path as above.

As you get closer to

The value of is also smaller and the heading angle

Also becomes smaller.

를 주차 완료점(주차장 좌표계 원점) 방향으로 차량의 속도에 따른

또는

의 변화만큼 이동시키면서 차량의 포즈

까지 클로소이드 주차경로 생성을 주차 완료시까지 계속한다. Towing point under these conditions

In the direction of the parking completion point (the origin of the parking lot coordinate system) according to the vehicle speed.

or

The vehicle's pose while moving as much as the change of

The creation of the clothoid parking route is continued until parking is completed.

가 미리 설정된 임계치 이하가 되면, 아래와 같은 식으로 토잉점을 주차 완료점 방향으로 이동시킨다. According to this embodiment, with reference to the distance between the towing point and the vehicle,

When is below the preset threshold, the towing point is moved toward the parking completion point in the following manner.

As shown in Equation 12, the towing point moves in the direction of the parking completion point based on the speed of the vehicle.

5 is a flowchart illustrating a process of generating a closed parking path for autonomous parking according to an exemplary embodiment of the present invention.

Referring to FIG. 5, the apparatus for generating a parking route receives an image of a parking space through a camera (step 500).

Here, the camera may be a front or rear camera of the vehicle.

The image input in step 500 is converted into a top view image, and the parking route generating apparatus sets a towing point and a parking completion point on the parking space coordinate system through the top view image (step 502).

Here, the parking completion point is the origin on the parking space coordinate system, and the towing point is set to have a y coordinate and a heading angle similar to the parking completion point.

Next, a clothoid curve from the initial pose of the vehicle to a preset towing point is generated (step 504).

Thereafter, the rate of change of the curvature of the clothoid curve is updated according to the movement of the vehicle (step 506).

The parking route generating apparatus determines whether the vehicle is close to the towing point (step 508), and when the vehicle approaches the towing point by a preset distance or less, moves the towing point toward the parking completion point (step 510).

The apparatus for generating a parking route generates a closed parking route between the vehicle's pose (center of the rear wheel axis) and the moving towing point (step 512).

The above-described embodiments of the present invention have been disclosed for purposes of illustration, and those skilled in the art having various knowledge of the present invention will be able to make various modifications, changes, and additions within the spirit and scope of the present invention. It should be regarded as belonging to the following claims.

Claims (10)

As a parking route generating device for autonomous parking,
Processor; And
Including a memory connected to the processor,
The memory,
The parking space video is input through the camera,
Set the towing point and the parking completion point on the parking space coordinate system using the parking space image,
Generate a clothoid curve from the initial pose of the vehicle to the set towing point,
Updating the rate of change of the curvature of the clothoid curve according to the movement of the vehicle,
When the vehicle approaches the set towing point, to create a closesoid parking path while moving the towing point toward the parking completion point,
A parking route generating device that stores program instructions executable by the processor. The method of claim 1,
The parking space coordinate system is defined by x, y and heading angles,
The towing point is set to have a y-coordinate and a heading angle similar to the parking completion point. The method of claim 2,
The program instructions,
When the reference point of the vehicle is located within a preset distance to the set towing point, the parking route generating device generates the closesoid parking route while moving the towing point in the x coordinate direction of the parking completion point. The method of claim 3,
The reference point of the vehicle is set to the x, y and heading angles of the rear wheel axis center of the vehicle on the vehicle coordinate system. The method of claim 3,
The program instructions,
A parking path generating device for moving the towing point in the direction of the parking completion point based on the speed of the vehicle. The method of claim 4,
The clothoid curve is defined by the following formula,
[Equation]

The program instructions,
Obtaining the distance between the reference point of the vehicle and the set towing point according to the movement of the vehicle,
A parking route generating device that calculates each coefficient of the clothoid curve by using the distance between the reference point of the vehicle and the set towing point, the y coordinate of the set towing point, and a heading angle. As a method of creating a parking route for autonomous parking,
(a) receiving an image of a parking space through a camera;
(b) setting a towing point and a parking completion point on a parking space coordinate system using the parking space image;
(c) generating a clothoid curve from the initial pose of the vehicle to the set towing point;
(d) updating a rate of change of curvature of the clothoid curve according to the movement of the vehicle; And
(e) when the vehicle approaches the set towing point, moving the towing point in the direction of the parking completion point and generating a closed parking route. The method of claim 7,
The parking space coordinate system is defined by x, y and heading angles,
The towing point is set to have a y-coordinate and a heading angle similar to the parking completion point. The method of claim 8,
In the step (e), when the reference point of the vehicle is located within a preset distance to the set towing point, the towing point is moved in the direction of the x coordinate of the parking completion point, and the parking path is generated to generate the closesoid parking path. Way. A program recorded on a recording medium performing the method according to claim 8.

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