CN116295488A

CN116295488A - Pavement full-coverage path generation method applied to Ackerman vehicle and vehicle

Info

Publication number: CN116295488A
Application number: CN202310252889.1A
Authority: CN
Inventors: 廖文龙; 张利峰; 何弢; 张润玺
Original assignee: Shanghai Kuyi Robot Co ltd; Kuwa Technology Co ltd
Current assignee: Shanghai Kuyi Robot Co ltd; Kuwa Technology Co ltd
Priority date: 2023-03-16
Filing date: 2023-03-16
Publication date: 2023-06-23

Abstract

The invention discloses a pavement full-coverage path generation method applied to an ackerman vehicle, which is used for planning a vehicle running path and comprises the following steps of: s1, obtaining a pavement ID; s2, obtaining data from the high-definition map according to the ID; s3, shifting; s4, obtaining an initial path; s5, obtaining key points between adjacent obstacles; s6, obtaining a zigzag path; s7, selecting a starting point according to the position of the vehicle, connecting the crossed path and the non-collision path, and controlling the vehicle to run according to the path; the non-collision path is a path along which the vehicle is controlled to travel without collision with the tree pool. The method generates a coverage rate higher for the sidewalk with the multi-tree pool obstacle, is suitable for the coverage path of the ackerman vehicle, better solves the problem of traversing and covering the area between tree pools by the generated path, and provides a better reference for completing the traversing of the vehicle.

Description

Pavement full-coverage path generation method applied to Ackerman vehicle and vehicle

Technical Field

The invention relates to the field of robot or vehicle path planning, in particular to a pavement full-coverage path generation method applied to an ackerman vehicle and the vehicle.

Background

In the field of robot or vehicle autopilot technology, path planning is of paramount importance, and traversing path planning (CPP) has become a subject of intense research in the field of robot applications, such as autonomous cleaning, lawn trimming and agriculture, and also including exploration, mapping, searching and rescue. Robotic end effectors may also benefit from CPPs, such as surface treatment applications (milling, laser cleaning, painting, deposition modeling printing, manufacturing inspection, etc.). CPP is a method of determining a path that covers all points from an initial state to a final state while detecting and avoiding obstacles in a target environment. Generally speaking, the objective of traversal path generation methods is to find an optimal coverage path to generate collision-free trajectories by reducing travel time, processing speed, energy costs, number of turns along the path length, and low overlap rate.

In the prior art, revisitingBoustrophedonCoveragePath PlanningasaGeneralizedTravelingSalesmanProblem, a combination of cow farming decomposition and travel business problems is proposed. As shown in fig. 1 and 2. The specific practice is to abstract the coverage area and the obstacle into polygons, decompose the traversing area into cells by cow cultivation decomposition, and execute cow cultivation path for each cell. Fig. 2 shows straight line segment generation in an x-axis monotonic polygon. We initialize the first straight line segment at the leftmost vertex parallel to the y-axis, which we call the scan direction. Generally, we limit the scan direction to be collinear with one of the boundaries of the polygon, as these directions have been shown to cover the polygon with a minimum number of straight line segments. Individual straight line segments are generated by alternating between intersecting the line in the y-direction with the polygon and offsetting the line from the leftmost to rightmost vertex. As shown in fig. 3, the units are finally connected, which method expresses this as a traveller problem, with the aim of finding the shortest path in each polygonal unit (point ellipsoid) to access exactly one scanning pattern (gray point) in the process from the start node ns to the target node ng. Fig. 4 shows a scenario in which it generates a full coverage path for a lawn.

The above-described technique has the following drawbacks:

(1) The characteristics of the algorithm are only suitable for large regular areas such as squares, farmlands and lawns, and are not suitable for long-strip areas such as sidewalks, and in the sidewalk, the algorithm is divided into too many units due to the fact that a large number of obstacles such as tree pools exist, so that too many turning paths are generated, and the energy cost is greatly increased;

(2) The algorithm searches the shortest path between two points through the Euclidean distance, so that the path is only suitable for robots with flexibility such as unmanned aerial vehicles, all-direction robots and the like, and the Ackerman vehicle is not suitable for the robots;

(3) Often, a narrower area is present in the sidewalk, and in this way, the cell lysis method may occur in a narrow area, which is not handled.

Disclosure of Invention

Aiming at the problems in the prior art, the patent provides a pavement full-coverage path generation method applied to an Ackerman vehicle and the vehicle, wherein the pavement with multiple tree pool barriers generates a coverage path which is higher in coverage rate and suitable for the Ackerman vehicle, and the generated path can solve the problem of traversing coverage of areas among tree pools and provides references for vehicle completion traversal. In order to achieve the above purpose, the present invention adopts the following technical scheme: the pavement full-coverage path generation method applied to the ackerman vehicle is used for planning a vehicle driving path and comprises the following steps of:

s1, inputting a pavement ID to be traversed;

s2, obtaining data from the high-definition map HDMap according to the ID and performing sampling processing;

s3, taking a boundary as a reference line to offset to the opposite side;

s4, checking whether the distance between the current path and the opposite side boundary is smaller than a safety distance, if so, storing the current path and continuing to shift to the opposite side, and if so, obtaining an initial path;

s5, obtaining key points between adjacent obstacles by judging whether collision occurs with the obstacles;

s6, obtaining a cross path according to the key points; obtaining a zigzag path according to the outermost collision path and the innermost collision path; wherein, the outermost collision path is: the tree pool is collided with, but the path farthest from the road boundary at one side of the tree pool is the path closest to the collision path at the innermost layer;

s7, selecting a starting point according to the position of the vehicle, connecting the crossed path and the non-collision path, and controlling the vehicle to run according to the path; the non-collision path is a path along which the vehicle is controlled to travel without collision with the tree pool.

Further, in S2, the pavement boundary information and the obstacle information to be traversed are obtained through a high-definition map, then in S3, the pavement boundary is firstly screened through a slope k, and when the difference between the slopes of the front point and the rear point is larger than 1, the pavement boundary is added into a pavement boundary vertex set.

Further, in S2, the sampling process is: referring to an S axis of a current sidewalk under an SL coordinate system, sampling is carried out once every first preset length, left_point and right_point of sampling points on the current S axis are obtained until the end of the sidewalk, and all the left_point and right_point are saved, wherein the left_point and the right_point extend to two sides by a second preset length taking the S axis as the center, and the second preset length is equal to half of the width of the vehicle plus a safety distance.

Further, the first preset length is 0.3m, and the safety distance is 0.15m.

Further, in S3 and S4, a smoother is selected according to the curvature of the left and right boundaries of the pavement, and is translated to another boundary as a reference line, the distance of each translation is determined by the width of the vehicle, the first translation distance is set to be a safe distance, the translation is stopped until the second translation exceeds the safe distance of the opposite side lane, and finally the opposite side boundary is used as the reference line to make a translation of the safe distance in the opposite direction, so that the edge portion of the opposite side can be covered.

Further, in S3 and S4, the maximum width of the current sidewalk is first obtained, and then the number of times of required traversal is calculated according to the maximum width.

Further, the safety width is equal to half the vehicle width plus a safety distance.

Further, in S5, by performing collision judgment on the vehicle Box and the Polygon of the obstacle (tree pool), taking the self-generated path as a reference line, firstly, assuming that the vehicle is at the path starting point, judging whether the vehicle collides, if so, shifting forward by 0.3m along the path until no collision occurs, shifting again until collision occurs with the tree pool, taking the previous point as the non-collision key point, adding the non-collision key point into the set, and circularly processing until the road end, thus obtaining the non-collision key points between the two tree pools or the tree pool and the boundaries of the two ends, and saving the front and rear tree pool IDs and the driving direction of the collision point.

Further, in S6, the path that does not generate an intersection with the tree pool (hereinafter referred to as a collision-free path) remains the original path, and is directly added to the traversal path, and the path that has an intersection with the tree pool (hereinafter referred to as a collision-free path) remains only when the two tree pools are far apart, and is generated by the key point when the tree pools are close, where the distance is 10m. It is assumed here that the tree pool has at most intersections with the first two paths. Firstly, the first key point of the second path is the starting point of entering the tree pool, the next target is the key point of the opposite side first layer, and the first key point of the first path is connected, wherein the first key point of the opposite side first layer is used for reversing, and a buffer point is added before the key point of the opposite side is connected for adjusting the position of the vehicle, so that reversing is better realized. The areas among all the tree pools are processed by the same method, half of the areas are traversed, and the whole area can be traversed by traversing the areas in opposite directions once and twice for entering the areas among the tree pools. And the path passing through the tree pool is obtained by outwards shifting a line segment formed by connecting the collision path at the outermost side with key points at two sides obtained by judging the collision of the tree pool.

The invention also provides a vehicle, which comprises a control system and a sensing system, wherein the control system adopts any one of the pavement full-coverage path generation methods applied to the ackerman vehicle to plan a driving path.

Compared with the prior art, the method acquires the key points between the tree pools in a collision mode, regularly connects the key points between the tree pools to form cross traversal, and completes the traversal by entering the area between the adjacent tree pools twice, so that the area between the tree pools is well covered; the invention prevents turning around in a reversing way, and the turning around is only carried out at two ends of the road, thereby improving the traversing efficiency; the method generates a coverage path which has high coverage rate and is suitable for the ackerman vehicle aiming at the sidewalk with the multi-tree pool obstacle, and provides an application reference for area traversal coverage for the automatic driving sanitation vehicle and the like.

Drawings

FIGS. 1-4 are schematic diagrams of the prior art;

fig. 5 is a schematic diagram of the path planning of the present invention.

Detailed Description

The following description of the embodiments of the present invention will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present invention, but not all embodiments. All other embodiments, which can be made by those skilled in the art to which the embodiments of the invention are applied without inventive faculty, are intended to fall within the scope of the invention.

The pavement full-coverage path generation method applied to the ackerman vehicle is used for planning a vehicle driving path and comprises the following steps of:

s1, inputting a pavement ID to be traversed;

s3, taking a boundary as a reference line to offset to the opposite side;

The invention uses the high-definition map to number all the sidewalk sections to be traversed, so as to be beneficial to generating, optimizing, managing and quickly calling the path according to the number. When the primary path is planned, a high-definition map of a target road section is quickly obtained through the ID number of the sidewalk, so that the shape and the size of the road section and the position and the size of obstacles such as a tree pool are obtained, the basic data are obtained, and then the planning of the traversal path is carried out according to rules. One path is firstly planned by one side boundary, then a second path is made by shifting a certain distance to the opposite side when turning back, and the like until the whole sidewalk is covered. When a path is planned, when obstacles such as a tree pool are blocked in the path, collision points are calculated to obtain key points, a saw-tooth traveling path of the vehicle entering the road surface between adjacent tree pools is planned according to the key points, a complete traversing path is finally obtained and provided for the vehicle, and the vehicle selects a starting point according to the position of the vehicle and travels along the path to finish the operation.

The invention generates a coverage rate higher for the sidewalk with the multi-tree pool obstacle, is suitable for the coverage path of the ackerman vehicle, provides a zigzag coverage path for the actual situation as an alternative route, and the generated path better solves the problem of traversing coverage of the area between tree pools and provides a better reference for completing traversing of the vehicle.

In some embodiments, in S2, the boundary information and the obstacle information of the sidewalk to be traversed are obtained through the high-definition map, where an SL coordinate system of the sidewalk may be established according to the proportion and the image analysis of the high-definition map, so as to obtain parameters such as the size, the coordinates, and the like of the sidewalk level obstacle; and in S3, the pavement boundary is firstly screened once through the slope k, and when the slope difference between the front point and the rear point is larger than 1, the pavement boundary is added into the pavement boundary vertex set. In practical applications, an average method is generally adopted for traversing, and the distances between adjacent paths are the same.

In S2, the corresponding process is as follows: referring to an S axis of a current pavement in an SL coordinate system, setting a first preset length of sampling to be 0.3m (the value can be determined according to actual needs), sampling once every 0.3m, obtaining left_point and right_point of sampling points on the current S axis until the end of the pavement, and storing all the left_point and right_point until the end of the pavement, wherein the left_point and the right_point extend to two sides by taking the S axis as a center by a second preset length, and the second preset length is equal to half of the width of a vehicle plus a safety distance, for example, the width of the vehicle is 0.9m, the safety distance is 0.15m, and the second preset length is 0.6m.

In S3 and S4, a smoother is selected according to the curvature of the left and right boundaries of the sidewalk, the smoother is taken as a reference line to translate towards the other boundary, the distance of each translation is determined by the width of the vehicle, the first translation distance is kept a safe distance until the translation is stopped when the translation exceeds the safe distance of the opposite side lane again, and finally the opposite side boundary is taken as the reference line to translate for a safe distance in the opposite direction, so that the edge part of the opposite side can be covered.

In S3 and S4, firstly, the maximum width of the current sidewalk is obtained, then the number of times of required traversal is calculated according to the maximum width, the specific method is that firstly, the safety widths on two sides of a traversal path are set, then the maximum width of the current sidewalk is subtracted by two times of the safety widths, and the remaining width is divided by the width of the vehicle, namely the number of times of required traversal of the current sidewalk.

Specific examples are: in S3 and S4, the safety width is equal to half the width of the vehicle plus the safety distance. The width of the current traversed vehicle is 0.9m, the safety distance is set to be 0.15m, so that the safety width at two sides of the two traversed paths is 0.6m, 1.2m (0.9+0.15x2=1.2m) is subtracted from the maximum width of the current sidewalk, and the remaining width is divided by 0.9, namely the number of times the current sidewalk needs to traverse the paths.

In S5, collision is determined by using the vehicle Box and the Polygon (outer frame) of the obstacle (generally, tree pool), the generated path is taken as a reference line, firstly, the vehicle is assumed to be at the starting point of the path, whether the vehicle collides or not is determined, if so, the vehicle is shifted forward by 0.3m along the path until the vehicle does not collide, the point is taken as a key point between the tree pools, the vehicle is shifted again until the vehicle collides with the tree pools, the previous point is taken as a key point of the vehicle which does not collide, the vehicle is added into a set, and the vehicle is circulated until the vehicle reaches the end of the road, so that non-collision key points between the two tree pools or the tree pools and the boundaries of the two ends can be obtained, and the front and rear tree pools IDs and the running directions of the collision points are saved.

In S6, the path that does not intersect with the tree pool (hereinafter referred to as collision-free path) remains the original path, and is directly added to the traversal path, and the path that intersects with the tree pool (hereinafter referred to as collision-free path) remains only when the two tree pools are far apart, and is generated by the key point when the tree pools are close, for example, the distance may be set to 10m. Assuming that the tree pool has an intersection point with the first two paths at most, firstly, the first key point of the second path is the starting point for entering the tree pool, the next target is the key point of the opposite side first layer, and then the first key point of the first path is connected, wherein the first key point of the opposite side first layer is used for reversing, and a buffer point is added before the key point of the opposite side is connected for adjusting the position of the vehicle, so that reversing is better realized. The areas among all the tree pools are processed by the same method, half of the areas are traversed, and the whole area can be traversed by traversing the areas in opposite directions once and twice for entering the areas among the tree pools. And the path passing through the tree pool is obtained by outwards shifting a line segment formed by connecting the collision path at the outermost side with key points at two sides obtained by judging the collision of the tree pool.

As shown in fig. 5, in the high-definition map, the ID00100 sidewalk is shown, the lower side (i.e., R side) edge of the sidewalk is taken as a reference line, the planned path is taken as a starting point, the planned path is firstly shifted to 2 points to the R side, then is forward driven to the key point 3 (the point is as close to the boundary of the tree pool as possible but no collision occurs), then is reversed to 4 points, the traversing of the path which is intersected with the tree pool from the starting point to the tree pool is completed, then the upper L side is shifted to 5 points, at this time, the reversing of the vehicle to 1 point can be controlled, the traversing between 1 point and 5 points can be completed, or the reversing can be not performed, then is driven to 6 points, the reversing to 7 points is carried out, the vehicle shape is adjusted to 8 points, then is reversed to 9 points, the reversing to 10 points is shifted to the left side from 9 points, the reversing to 6 points, the reversing to 11 points, and the like, the traversing to 32 points is completed according to the number, wherein the traversing to 20 points can be reversed to 16 points, the reversing to 20 points, the traversing to 21 points is completed, and the final traversing of the sidewalk is completed. The walkways between tree pools T1, T2, T3 implement a very adapted job path using the illustrated zigzag path.

The invention also provides a vehicle, which comprises a control system and a sensing system, wherein the control system can plan a running path by adopting any one of the pavement full-coverage path generation methods applied to the ackerman vehicle, or can download the planned path from a server, then set a starting position and an ending position according to the vehicle position and finish operation according to the path.

The foregoing is only a preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art, who is within the scope of the present invention, should make equivalent substitutions or modifications according to the technical scheme of the present invention and the inventive concept thereof, and should be covered by the scope of the present invention.

Claims

1. The pavement full-coverage path generation method applied to the ackerman vehicle is used for planning the vehicle running path and is characterized by comprising the following steps of:

s1, inputting a pavement ID to be traversed;

s3, taking a boundary as a reference line to offset to the opposite side;

2. The method for generating a full coverage path of a pavement applied to an ackerman vehicle according to claim 1, wherein in S2, pavement boundary information and obstacle information to be traversed are obtained through a high-definition map, then in S3, pavement boundaries are screened once through a slope k, and when a slope difference between a front point and a rear point is greater than 1, the pavement boundary is added into a pavement boundary vertex set.

3. The sidewalk full-coverage path generation method applied to ackerman vehicle according to claim 2, wherein in S2, the sampling process is: referring to an S axis of a current sidewalk under an SL coordinate system, sampling is carried out once every first preset length, left_point and right_point of sampling points on the current S axis are obtained until the end of the sidewalk, and all the left_point and right_point are saved, wherein the left_point and the right_point extend to two sides by a second preset length taking the S axis as the center, and the second preset length is equal to half of the width of the vehicle plus a safety distance.

4. The method for generating a full coverage path for a pavement for an ackerman vehicle according to claim 3, wherein the first preset length is 0.3m and the safety distance is 0.15m.

5. The method for generating a full coverage path for a pavement of ackerman vehicles according to claim 2, wherein in S3 and S4, a smoother one is selected according to the curvature of the left and right boundaries of the pavement, and is translated toward the other boundary as a reference line, the distance of each translation is determined by the width of the vehicle, the first translation distance is set to be a safe distance, the translation is stopped until the translation again exceeds the safe distance of the opposite lane, and finally the opposite boundary is translated toward the opposite direction as a reference line, mainly for enabling the edge portion of the opposite side to be covered.

6. The method for generating a full coverage path for a pavement of an ackerman vehicle according to claim 5, wherein in S3 and S4, the maximum width of the current pavement is obtained first, then the number of times of required traversal is calculated according to the maximum width, the method is that the safety width on both sides of the traversal path is set first, then the maximum width of the current pavement is subtracted by two times of the safety width, and the remaining width is divided by the width of the vehicle, namely the number of times of required traversal of the current pavement.

7. The method of generating a full coverage path for a pavement for an ackerman vehicle according to claim 6, wherein the safety width is equal to half of the vehicle width plus a safety distance.

8. The pavement full coverage path generation method applied to ackerman vehicles according to claim 2, characterized in that in S5, collision is judged by a vehicle Box and a Polygon of an obstacle (tree pool), a self-generated path is taken as a reference line, whether the vehicle collides or not is firstly judged, if the vehicle collides, the vehicle is shifted forward by 0.3m along the path until the vehicle does not collide, the point is taken as a key point between the tree pools, the vehicle is shifted again until collision occurs with the tree pools, the previous point is taken as an uncorrupted key point, and the vehicle is circularly processed until the end of the road, so that non-collision key points between the two tree pools or the boundaries between the tree pools and the two ends can be obtained, and the front and rear tree pool IDs of the collision point and the driving direction are saved.

9. The method for generating a full-coverage path for a pavement of an ackerman vehicle according to claim 2, wherein in S6, a path (hereinafter referred to as a collision-free path) which does not generate an intersection with a tree pool is reserved, the path is directly added to a traversing path, a path (hereinafter referred to as a collision-free path) which has an intersection with a tree pool is reserved only when two tree pools are far apart, and the path is generated by a key point when the tree pools are close, wherein the distance is 10m. It is assumed here that the tree pool has at most intersections with the first two paths. Firstly, the first key point of the second path is the starting point of entering the tree pool, the next target is the key point of the opposite side first layer, and the first key point of the first path is connected, wherein the first key point of the opposite side first layer is used for reversing, and a buffer point is added before the key point of the opposite side is connected for adjusting the position of the vehicle, so that reversing is better realized. The areas among all the tree pools are processed by the same method, half of the areas are traversed, and the whole area can be traversed by traversing the areas in opposite directions once and twice for entering the areas among the tree pools. And the path passing through the tree pool is obtained by outwards shifting a line segment formed by connecting the collision path at the outermost side with key points at two sides obtained by judging the collision of the tree pool.

10. A vehicle, characterized in that an ackerman structure is adopted, and the control system comprises a control system and a sensing system, wherein the control system adopts the pavement full coverage path generation method applied to the ackerman vehicle according to any one of claims 1-9 to plan a running path.