A parking path generation method, device and computer program product

Abstract

The application relates to a parking path generation method and device and a computer program product, comprising: receiving an initial parking path, the initial parking path comprising at least two path segments; acquiring the curvature and the curvature change rate of the starting point or the ending point of each path segment; determining the length of the spiral curve corresponding to each path segment according to the preset ending point curvature of the spiral curve and the curvature and the curvature change rate of the starting point or the ending point of each path segment; constructing the spiral curve corresponding to each path segment according to the length of the spiral curve corresponding to each path segment; and generating a new parking path according to the spiral curve corresponding to each path segment and the at least two path segments. Through the application, the technical problem that when the curvature at the path turning point of the parking path obtained according to a geometric method or a search method is not zero, the vehicle exists the phenomenon of turning in place can be solved.

Description

Technical Field

[0001] This application relates to the field of automatic parking technology, specifically to a parking path generation method, apparatus, and computer program product. Background Technology

[0002] Parking path generation methods are mainly divided into geometric methods and search-based methods. Geometric methods primarily rely on parking space and obstacle information, calculating arcs based on the vehicle's minimum turning radius, and generating a parking path that avoids obstacles by adding straight lines to the arcs. Search-based methods calculate a locally optimal path for the vehicle by acquiring real-time data on parking spaces and drivable areas identified by the environmental perception system. Calculation methods include hybrid AlphaGo algorithms and Restricted Real-Time (RRT) algorithms. After obtaining the initial parking path using geometric and search methods, smoothing methods such as optimization are applied to smooth the initial parking path. The smoothed parking path is then provided to the control system as trajectory points. The control system uses the smoothed parking path as a reference and employs lateral and longitudinal control algorithms to track the trajectory points on the parking path, enabling the vehicle to park in the parking space.

[0003] However, parking paths obtained using geometric or search-based methods often have non-zero curvature at turning points. When this parking path is provided to the control system as trajectory points, the vehicle exhibits a tendency to turn in place. To address this issue, a method of replacing parts of the original parking path with a spiral curve has been proposed. However, this method suffers from the need to calculate offsets and poor versatility. Furthermore, the length of the spiral curve is typically calculated based on the maximum vehicle speed and the time required for the steering wheel to reach its maximum angle, or set based on empirical values. Neither method considers the original trajectory curvature, leading to abrupt changes in curvature and hindering the control system's ability to track trajectory points. Summary of the Invention

[0004] The purpose of this application is to propose a parking path generation method and apparatus, as well as a computer program product, to solve the technical problem that when the curvature at the turning point of a parking path obtained by geometric methods or search methods is not zero, the vehicle turns in place.

[0005] To achieve the above objectives, according to a first aspect of this application, a parking path generation method is provided, the method comprising:

[0006] Receive an initial parking path, which includes at least two path segments;

[0007] Obtain the curvature and rate of change of curvature at the start or end point of each path segment;

[0008] The length of the spiral curve corresponding to each path segment is determined based on the preset curvature of the spiral curve endpoint and the curvature and rate of change of curvature of the starting or ending point of each path segment.

[0009] Construct the spiral curve corresponding to each path segment based on the length of the spiral curve corresponding to each path segment;

[0010] A new parking path is generated based on the spiral curve corresponding to each path segment and the at least two path segments.

[0011] According to a second aspect of this application, a parking path generation apparatus is provided, the apparatus including a module for performing the method described in the first aspect of this application.

[0012] According to a third aspect of this application, a parking path generation apparatus is provided, comprising:

[0013] A communication interface used for communicating with other electronic devices;

[0014] Memory is used to store computer program instructions;

[0015] A processor is configured to execute the computer program instructions to support the implementation of the method according to the first aspect of this application based on the parking path generation device.

[0016] According to a fourth aspect of this application, a computer program product is provided, including computer program instructions that instruct a computer device to perform an operation corresponding to the method described in the first aspect of this application.

[0017] This application proposes a parking path generation method, apparatus, and computer program product. By introducing a spiral curve to smooth the initial parking path, the curvature at the end of the final parking path is zero, thus solving the problem of vehicles turning in place. The length of the spiral curve corresponding to each path segment is determined by the preset curvature at the end of the spiral curve, as well as the curvature and rate of change of curvature at the beginning or end of each path segment. This method can avoid abrupt changes in the curvature of the connecting spiral curves and the curvature at the end of the original path, ensuring the curvature continuity of the parking path at turning points. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings required in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 This is a flowchart of a parking path generation method in an embodiment of this application.

[0020] Figure 2 This is a schematic diagram of the coordinate system for the spiral curve in an embodiment of this application.

[0021] Figure 3This is a schematic diagram of the splicing of spiral curves in an embodiment of this application. Detailed Implementation

[0022] The detailed description of the accompanying drawings is intended to illustrate the present embodiments of this application and is not intended to represent only the forms in which this application can be implemented. It should be understood that the same or equivalent functions can be accomplished by different embodiments intended to be included within the spirit and scope of this application.

[0023] See Figure 1 One embodiment of this application provides a parking path generation method, the method comprising the following steps:

[0024] Step S10: Receive the initial parking path, which includes at least two path segments.

[0025] Specifically, when using automatic parking, multiple adjustments are often required to park the vehicle in the parking space. In this case, the initial parking path will contain at least two paths, with a turning point between adjacent paths. For example, if a vehicle needs to park in a parking space, the initial parking path may include the first path (turning to avoid obstacles) and the second path (entering the new parking space).

[0026] Step S20: Obtain the curvature and rate of change of curvature of the starting or ending point of each path segment.

[0027] Specifically, in the example above, the turning point of two adjacent path segments is the end point of the first path segment and the starting point of the second path segment. Although they are the same point, the curvature and rate of change of curvature of the end point of the first path segment are different from those of the starting point of the second path segment. The curvature and rate of change of curvature of the end point of the first path segment should be calculated and determined based on the first path segment, and the curvature and rate of change of curvature of the starting point of the second path segment should be calculated and determined based on the second path segment. In other words, a sudden change in curvature will occur at the turning point. If this is not handled, it will cause the vehicle to turn in place.

[0028] Step S30: Determine the length of the spiral curve corresponding to each path segment based on the preset curvature of the spiral curve endpoint and the curvature and rate of change of curvature of the starting or ending point of each path segment.

[0029] Specifically, in this embodiment, the preset curvature of the spiral curve endpoint is 0. In the above example, the length of the spiral curve corresponding to the first path segment needs to be determined based on the curvature of the spiral curve endpoint, the curvature of the endpoint of the first path segment, and the rate of change of curvature. The length of the spiral curve corresponding to the second path segment needs to be determined based on the curvature of the spiral curve endpoint, the curvature of the starting point of the second path segment, and the rate of change of curvature.

[0030] The formula for calculating the length of a spiral curve is as follows:

[0031]

[0032] Where s is the length of the spiral curve, s_k is the curvature at the end or beginning of the path, e_k is the curvature at the end of the spiral curve, and d_k is the rate of change of curvature at the end or beginning of the path.

[0033] Specifically, the length of the spiral curve corresponding to each path segment is determined by the preset curvature of the spiral curve endpoint and the curvature and rate of change of curvature at the start or end of each path segment. This method can avoid abrupt changes in the curvature of the connecting spiral curve and the curvature at the end of the original path, ensure the curvature continuity of the parking path at the turning point, reduce the impact on the vehicle steering system, avoid severe friction between the tires and the ground, and improve the safety and comfort of parking.

[0034] Step S40: Construct the spiral curve corresponding to each path segment based on the length of the spiral curve corresponding to each path segment.

[0035] Specifically, spiral curves are usually described by specific mathematical equations. Common spiral curve types include Clothoid and Cornu (Euler-Spiral) curves, both of which provide continuously varying curvature and are suitable for vehicle path planning. These mathematical equations contain parameters such as initial curvature, terminal curvature, and curve length. Therefore, based on the known spiral curve length and the curvature at the start and end points, these parameters can be solved to obtain the mathematical equation of the spiral curve.

[0036] Step S50: Generate a new parking path based on the spiral curve corresponding to each path segment and the at least two path segments;

[0037] Specifically, after obtaining the spiral curve corresponding to each path segment, the spiral curve can be used to smooth the at least two path segments to obtain an optimized new parking path, which enables the vehicle to achieve smooth and safe steering during parking, while improving parking efficiency and accuracy.

[0038] In some specific embodiments, step S40 further includes:

[0039] Step S401: Based on the curvature of the starting or ending point of each path segment, the curvature of the ending point of the spiral curve, and the length of the spiral curve corresponding to each path segment, obtain the rate of change of curvature of the spiral curve corresponding to each path segment.

[0040] Specifically, the rate of change of curvature of a cyclotron is constant, and its curvature changes linearly with the arc length, mathematically defined as:

[0041]

[0042] Where: k is curvature, dk is the change in curvature, which can be calculated based on the curvature of the starting and ending points of the spiral curve. In the example above, the starting point of the spiral curve corresponding to the first path segment is the ending point of the first path segment, the starting point of the spiral curve corresponding to the second path segment is the starting point of the second path segment, s is the length of the spiral curve calculated in step S30, ds is the change in the length of the spiral curve, which is actually ds = s, and c is the rate of change of curvature, which is a constant.

[0043] Step S402: Construct the spiral curve corresponding to each path segment based on the length and curvature change rate of each path segment.

[0044] Specifically, for each path segment's spiral curve, its length, rate of change of curvature, starting curvature, and ending curvature are already known. This information provides sufficient parameters to define the shape of the spiral curve, thus allowing the construction of the spiral curve corresponding to each path segment. It should be noted that, given the length, rate of change of curvature, starting curvature, and ending curvature as constraints, multiple spiral curves may satisfy these constraints. Each curve has its unique shape and transition effect. The choice of which curve to use depends on specific application requirements and performance goals. For example, in this embodiment, a further constraint can be added: the spiral curves corresponding to adjacent path segments should fit as closely as possible, facilitating a smooth transition from the first path segment to the second.

[0045] In some specific embodiments, determining the length of the spiral curve corresponding to each path segment based on the preset curvature of the spiral curve endpoint and the curvature and rate of change of curvature of the starting or ending point of each path segment further includes:

[0046] Based on the standard coordinate system, the coordinates and tangent angles of each point on the spiral curve corresponding to each path segment are obtained according to the length and curvature change rate of the spiral curve corresponding to each path segment, and the spiral curve corresponding to each path segment in the standard coordinate system is generated according to the coordinates and tangent angles of each point.

[0047] The coordinate transformation matrix is ​​obtained by taking the tangent angle of each point on the spiral curve corresponding to each path segment. The spiral curve corresponding to each path segment in the standard coordinate system is transformed to the non-standard coordinate system based on the coordinate transformation matrix, so as to obtain the spiral curve corresponding to each path segment in the non-standard coordinate system.

[0048] Specifically, the standard coordinate system represents a rectangular coordinate system whose origin is established at a point with zero curvature, i.e., x0 = 0, y0 = 0, s0 = 0, k0 = 0, and this is an infinite series. Under the above assumptions, the coordinates and tangent angles of any point on the spiral curve corresponding to each path segment in the standard coordinate system are obtained as follows:

[0049]

[0050]

[0051] Where, x j Let y be the x-coordinate of point j on the spiral curve. j Let s be the ordinate of point j on the spiral curve. j Let α be the length of the spiral curve from its starting point to point j. j Let be the tangent angle at point j on the spiral curve, the standard coordinate system is a rectangular coordinate system with zero curvature at the origin, N is a preset value, i∈0~N, and ! is the factorial operator.

[0052] In applications, it's impossible to always start from a point where curvature is zero. For example, when connecting two circular arcs, the curvature changes from one non-zero curvature to another. In this case, the calculation methods of the standard coordinate system become limited. Furthermore, if the origin of the rectangular coordinate system is not established at a point where curvature is zero (referred to as a non-standard coordinate system), the mathematical processing becomes very complex. Therefore, this embodiment first calculates the coordinates and tangent angles of each point on the spiral curve based on the standard coordinate system, and then converts the calculation results to a non-standard coordinate system, such as... Figure 2 As shown.

[0053] In some specific embodiments, obtaining the coordinate transformation matrix based on the tangent angles at various points on the spiral curve corresponding to each path segment further includes:

[0054] For any point on the spiral curve corresponding to each path segment in the standard coordinate system, substitute the tangent angle at that point into the following matrix equation. Obtain the coordinate transformation matrix corresponding to any point, and transform the coordinates of any point in the standard coordinate system to a non-standard coordinate system based on the coordinate transformation matrix to obtain the coordinates of any point in the non-standard coordinate system.

[0055] Specifically, for any point j on the cyclotron curve, according to the relationship between the curvature and arc length of the cyclotron curve... Calculate the heading angle α of point j in the standard coordinate system XOY. j This allows us to obtain the coordinate transformation matrix between the non-standard coordinate system xoy and the standard coordinate system XOY corresponding to point j:

[0056]

[0057] The transformation relationship between the two coordinate systems with respect to the coordinates of point j is as follows:

[0058]

[0059] Where X0 and Y0 are the coordinates of the origin o of the non-standard coordinate system xoy in the XOY coordinate system, X j and Y j Let x be the coordinates of point j in the non-standard coordinate system xoy; j and y j Let j be the coordinates of point j in the non-standard coordinate system xoy;

[0060] Conversely, coordinates in the standard coordinate system XOY mapped to the non-standard coordinate system xoy are:

[0061]

[0062] The method in this embodiment first calculates the cyclotron curve based on the standard coordinate system, and then transforms the cyclotron curve in the standard coordinate system to a non-standard coordinate system. This allows the cyclotron curve to be calculated from a point where the curvature is non-zero, increasing the application scenarios of the cyclotron curve. It also simplifies the calculation process of the cyclotron curve with a non-zero curvature at the starting point and improves the program's calculation speed.

[0063] In some specific embodiments, step S50 further includes:

[0064] Step S501: The spiral curves corresponding to each constructed path segment are spliced ​​to the starting point or ending point of the corresponding path.

[0065] Specifically, in the example above, step S50 yields the first spiral curve corresponding to the first path segment and the second spiral curve corresponding to the second path segment. The starting point of the first spiral curve is connected to the ending point of the first path segment to form a new first path segment, and the starting point of the second spiral curve is connected to the starting point of the second path segment to form a new second path segment. During automatic parking, the vehicle first travels along the new first path segment, and then adjusts to travel along the new second path segment until it is parked in the parking space. Some adjustments may be needed between the new first path segment and the new second path segment, but these adjustments are easy to implement because there is no obvious curvature change during the adjustment process, and the vehicle will not turn in place.

[0066] The method in this embodiment splices a spiral curve at the turning point (where the curvature is not zero) of the initial parking path to smooth the initial parking path, so that the curvature at the end of the final parking path is zero. This solves the problem of the vehicle turning in place, does not replace part of the original path, does not require calculation of splicing offset, and improves the applicability of the smoothing method.

[0067] In some specific embodiments, step S50 further includes:

[0068] Step S502: Obtain the endpoint pose of the spiral curve corresponding to each path segment, and generate a straight line corresponding to each path segment based on the endpoint pose.

[0069] Step S503: Connect the straight lines corresponding to each path segment to the endpoint of the corresponding spiral curve.

[0070] Specifically, this embodiment takes into account the existence of control errors in actual situations, and the fact that the control selection of tracking points requires a forward aiming distance, which means that even if the curvature of the end of the spiral curve is 0, the steering wheel will still have a certain angle after the vehicle reaches the end of the curve, which may still result in a certain degree of stationary turning. Therefore, this embodiment adds a straight line at the end of the spiral curve to adjust the control loop.

[0071] For example, such as Figure 3 As shown, the planned initial parking path includes the first segment p1⌒p2 and the second segment p7⌒p8. The rectangle formed by the dashed lines represents the parking space. p2 and p7 are the turning points of the initial parking path (p2 and p7 are the same point). p2 is the end point of the first segment p1⌒p2, and p7 is the starting point of the second segment p7⌒p8. For the spiral curve corresponding to the first segment p1⌒p2, the length of the spiral curve is calculated based on the curvature and rate of change of curvature of point p2. After calculating the spiral curve in the standard coordinate system, it is transformed to the non-standard coordinate system. The curve is then spliced ​​to point p2 according to the coordinate system translation and rotation to form the spiral curve p2⌒p3. A straight line is spliced ​​according to the pose of p3 to form the straight line p3⌒p4. Finally, the first segment p1⌒p2 is smoothed into the path p1⌒p4, where p4 is the turning point of the smoothed first segment. Similarly, p7⌒p8 can be smoothed into p5⌒p8. By performing the above path smoothing operation at each turning point of the parking path, the problem of turning in place during parking can be solved, the parking control effect can be improved, and the comfort of the parking process can be enhanced.

[0072] Another embodiment of this application provides a parking path generation device, including a module for executing the parking path generation method described in the above embodiments. This device can be a hardware device, a software device, or a combination of hardware and software.

[0073] Another embodiment of this application also provides another parking path generation apparatus, including:

[0074] A communication interface used for communicating with other electronic devices;

[0075] Memory is used to store computer program instructions;

[0076] A processor is configured to execute the computer program instructions to support the parking path generation device in implementing the methods described in the above embodiments.

[0077] In this embodiment, the memory mainly includes a program storage area and a data storage area. The program storage area can store the operating device, applications required for at least one function, etc., and the data storage area can store related data, etc. Furthermore, the memory can be a high-speed random access memory, or a non-volatile memory, such as a plug-in hard disk, a smart media card (SMC), a secure digital card (SD), and a flash card, or other volatile solid-state storage devices.

[0078] The processor can be a central processing unit (CPU), or other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. The general-purpose processor can be a microprocessor, or the processor can be any conventional processor. The processor is the control center of the parking path generation device and connects to various parts of the parking path generation device using various interfaces and lines.

[0079] This application also provides a computer program product, including computer program instructions, which instruct a computer device to perform operations corresponding to the methods described in the above embodiments.

[0080] Specifically, the computer program product includes a series of computer program instructions that instruct a computer device to execute the parking path generation method described in this application. These instructions are code written in a computer program that defines how to perform specific operations. In this embodiment, these instructions are used to execute the parking path generation method of the above embodiments.

[0081] These program instructions are designed to be loaded onto a computer device and to instruct the device to perform specific operations, which refer to the various steps in the parking path generation method described in the above embodiments.

[0082] In this way, the computer program product provides a complete software solution that can run on various computer devices to implement the parking path generation method described in the above embodiments.

[0083] The various embodiments of this application have been described above. These descriptions are exemplary and not exhaustive, nor are they limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments. The terminology used herein is chosen to best explain the principles, practical applications, or technological improvements to the embodiments in the market, or to enable others skilled in the art to understand the embodiments disclosed herein.

Claims

1. A parking path generation method, characterized in that, The method includes: Receive an initial parking path, which includes at least two path segments; Obtain the curvature and rate of change of curvature at the start or end point of each path segment; The length of the spiral curve corresponding to each path segment is determined based on the preset curvature of the spiral curve endpoint and the curvature and rate of change of curvature of the starting or ending point of each path segment. Construct the spiral curve corresponding to each path segment based on the length of the spiral curve corresponding to each path segment; A new parking path is generated based on the spiral curve corresponding to each path segment and the at least two path segments; The step of determining the length of the spiral curve corresponding to each path segment based on the preset curvature of the spiral curve endpoint and the curvature and rate of change of curvature of the starting or ending point of each path segment further includes: Based on the standard coordinate system, the coordinates and tangent angles of each point on the spiral curve corresponding to each path segment are obtained according to the length and curvature change rate of the spiral curve corresponding to each path segment, and the spiral curve corresponding to each path segment in the standard coordinate system is generated according to the coordinates and tangent angles of each point. The coordinate transformation matrix is ​​obtained by taking the tangent angle of each point on the spiral curve corresponding to each path segment. The spiral curve corresponding to each path segment in the standard coordinate system is transformed to the non-standard coordinate system based on the coordinate transformation matrix, so as to obtain the spiral curve corresponding to each path segment in the non-standard coordinate system.

2. The method according to claim 1, characterized in that, The step of constructing the spiral curve corresponding to each path segment based on the length of the spiral curve corresponding to each path segment further includes: Based on the curvature of the starting or ending point of each path segment, the curvature of the ending point of the spiral curve, and the length of the spiral curve corresponding to each path segment, the rate of change of curvature of the spiral curve corresponding to each path segment is obtained. Construct a spiral curve for each path segment based on its length and rate of curvature change.

3. The method according to claim 2, characterized in that, The coordinates and tangent angle of any point on the spiral curve corresponding to each path segment in the standard coordinate system are obtained as follows: in, Point on the spiral curve j x-coordinate Point on the spiral curve j The ordinate, From the starting point to the point of the spiral curve j The length of the curve between them Point on the spiral curve j The tangent angle, wherein the standard coordinate system is a rectangular coordinate system with zero curvature at the origin. N This is a preset value, where i is 0~ N .

4. The method according to claim 3, characterized in that, The step of obtaining the coordinate transformation matrix based on the tangent angles at various points on the spiral curve corresponding to each path segment further includes: For any point on the spiral curve corresponding to each path segment in the standard coordinate system, substitute the tangent angle at that point into the following matrix equation. Obtain the coordinate transformation matrix corresponding to any point, and transform the coordinates of any point in the standard coordinate system to a non-standard coordinate system based on the coordinate transformation matrix to obtain the coordinates of any point in the non-standard coordinate system; The angle is the tangent angle.

5. The method according to claim 1, characterized in that, The step of generating a new parking path based on the spiral curve corresponding to each path segment and the at least two path segments further includes: The spiral curves corresponding to each constructed path segment are spliced ​​to the starting or ending point of the corresponding path.

6. The method according to claim 5, characterized in that, The step of generating a new parking path based on the spiral curve corresponding to each path segment and the at least two path segments further includes: Obtain the endpoint pose of the spiral curve corresponding to each path segment, and generate a straight line corresponding to each path segment based on the endpoint pose. Connect the straight lines corresponding to each path segment to the endpoint of the corresponding spiral curve.

7. A parking path generation device, characterized in that, The apparatus includes a module for performing the method according to any one of claims 1 to 6.

8. A parking path generation device, characterized in that, include: A communication interface used for communicating with other electronic devices; Memory is used to store computer program instructions; A processor for executing the computer program instructions to support the apparatus in implementing the method according to any one of claims 1 to 6.

9. A computer program product, characterized in that, It includes computer program instructions that instruct a computer device to perform an operation corresponding to the method as described in any one of claims 1 to 6.

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