A vertical parking method

Abstract

The application provides a vertical parking space parking method, a two-segment circular arc is used for planning a vehicle tail parking track in a vertical parking space, under the condition of meeting boundary constraints and collision avoidance constraints, a pose at a tangent position of the two-segment circular arc track and parameters of the two-segment circular arc track are adaptively calculated according to a relative position relationship between an initial position of a vehicle and a boundary obstacle, and a parking opposite space and a parking space are maximally utilized, so that an initial feasible area of parking can be effectively widened, and the two-segment circular arc track effectively reduces a number of times of vehicle rolling, and riding comfort is better.

Description

Technical Field

[0001] This invention relates to the field of automatic parking technology, and more particularly to a method for parking in a perpendicular parking space. Background Technology

[0002] With the rapid development of the automotive industry, automatic parking has become a common feature in modern cars. This function effectively assists or replaces the driver in parking operations in different environments, improving driving safety during the parking process. However, current automatic parking technology still faces the major challenge of ensuring passenger comfort while efficiently planning the trajectory within limited space.

[0003] Compared to parallel parking spaces, planning the rear-end parking trajectory for perpendicular parking spaces requires a larger parking area due to the vehicle's length during forward movement. Existing parking strategies typically employ multi-step parking, requiring repeated maneuvering (shifting gears while parking is one maneuver) to adjust the vehicle's position. During parking, issues with tracking and control accuracy can lead to parking failures, resulting in low efficiency. Furthermore, the frequent acceleration and deceleration caused by repeated maneuvering significantly reduces passenger comfort. Summary of the Invention

[0004] This invention provides a perpendicular parking method that aims to overcome the shortcomings of existing technologies, maximize the use of opposite parking space and parking space space, effectively widen the initial feasible parking area, and effectively reduce the number of times the vehicle has to maneuver around the parking space, resulting in better passenger comfort.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0006] This invention provides a method for parking in a perpendicular parking space, comprising:

[0007] Step 1: Establish a parking kinematics model based on the Ackermann steering model;

[0008] Step 2: Obtain the coordinates of the target parking space, lane boundaries, obstacles, and the vehicle's position in the parking scenario, and establish a local parking coordinate system based on the target parking space;

[0009] Step 3: Determine the effective range of the parking starting point that satisfies the two-segment parking trajectory;

[0010] Step 4: Determine whether the vehicle's current position is within the effective range of the parking starting point. If yes, proceed to the next step; otherwise, determine that the vehicle's current position cannot be used for two-stage parking and return to step 2.

[0011] Step 5: Calculate the pose of the trajectory switching point based on the initial parking position, the coordinates of the target parking space, and the width of the opposite lane, and calculate the parameters of the two arc trajectories based on the pose of the trajectory switching point.

[0012] Specifically, step 3 includes:

[0013] Step 301: Determine the lower and upper limits of the ordinate of the starting point of the parking trajectory that satisfies the two-segment parking trajectory.

[0014] Step 302: Based on the lower and upper limits of the ordinate of the parking starting point of the parking trajectory, draw the upper limit cutoff line and the lower limit cutoff line of the parking starting point in the local parking coordinate system, respectively. The range determined by the upper and lower limit cutoff lines of the parking starting point is the effective range of the parking starting point.

[0015] Specifically, the method for determining the lower limit of the vertical coordinate of the parking starting point includes: in the first arc trajectory of the two-segment parking trajectory, setting the first relationship when the vehicle is in a first state, wherein the first state is when the line connecting the right rear point of the vehicle and the center of the first arc trajectory is perpendicular to the parking space entrance line.

[0016] Specifically, the first relation is: y O1 -|O1V3'|>y P2 , where y O1 This represents the ordinate of the center O1 of the first circular arc trajectory, y p2 The vertical coordinate of the upper left corner point P2 of the target parking space is represented by |O1V3'|, and the length of the line connecting the right rear point V3 of the vehicle and the center O1 of the first arc trajectory when the vehicle is in the first state is represented by |O1V3'|.

[0017] Specifically, the lower limit of the vertical coordinate of the parking starting point is determined according to the following formula:

[0018]

[0019] Among them, y A1 The lower limit of the ordinate of the parking starting point, y p2 The ordinate of P2 represents the top left corner of the target parking space, s1 represents the safe distance between the vehicle and the lower boundary of the lane, and R represents the vertical coordinate of the target parking space. min W represents the minimum turning radius of this vehicle. v Indicates the width of this vehicle, L r This indicates the rear overhang length of the vehicle.

[0020] Specifically, the method for determining the upper limit of the vertical coordinate of the parking starting point includes: in the second arc trajectory of the two-segment parking trajectory, setting a second relational expression to be satisfied when the vehicle is in a second state, wherein the second state is that the line connecting the left front point of the vehicle and the center of the second arc trajectory is perpendicular to the opposite boundary.

[0021] Specifically, the second relation is: y O2 +|O2V1'| <y P1 +wr θ1>θ3

[0022] Among them, y O2 The y-coordinate represents the center O2 of the second circular arc trajectory. p1 The w represents the ordinate of the top right corner P1 of the target parking space. r The width of the oncoming lane is represented by |O2V1'|, which represents the length of the line connecting the front left point V1 of the vehicle and the center O2 of the second arc trajectory when the vehicle is in the second state. θ1 represents the central angle of the first trajectory segment, and θ3 represents the decision angle, which is determined according to the following formula:

[0023]

[0024] L represents the wheelbase of this vehicle. f W indicates the front overhang length of this vehicle. v Indicates the width of this vehicle, R min This indicates the vehicle's minimum turning radius.

[0025] Specifically, the upper limit of the vertical coordinate of the parking starting point is determined according to the following formula:

[0026]

[0027] Among them, y A2 The y-coordinate of the parking starting point represents the upper limit of the coordinate. p1 The w represents the ordinate of the top right corner P1 of the target parking space. r R indicates the width of the oncoming lane. min s2 represents the minimum turning radius of the vehicle, s2 represents the safe distance between the vehicle and the upper boundary of the lane, and L represents the track width of the vehicle. f W indicates the front overhang length of this vehicle. v This indicates the width of the vehicle.

[0028] Specifically, step 5 includes:

[0029] Step 501: Control the vehicle to drive to the parking starting point and control the initial heading angle of the vehicle to 0.

[0030] Step 502: Adaptively determine the length of the first arc trajectory based on the distance from the parking starting point to the opposite boundary of the target parking space, and control the vehicle to stop after it reaches the trajectory switching point;

[0031] Step 503: Switch the vehicle to reverse gear and turn the steering wheel to its limit in the opposite direction. Control the vehicle to reverse along the second arc trajectory into the parking end point of the target parking space.

[0032] Specifically, the coordinates of the parking start point, trajectory switching point, parking end point, and the vehicle's heading angle at the above locations are determined according to the following formula:

[0033] x A =x C +R min (1-cosθ2-sinθ1)

[0034] x B =x C +R min (1-cosθ2)

[0035] y B =y A +R min (1-cosθ1)

[0036] y C =y A +R min (1-cosθ1-sinθ2)

[0037]

[0038] θ2=π / 2-θ1

[0039] θ A =0,θ B =θ1,θ C =π / 2

[0040] in:

[0041] m = y P1 +W r -s2-R min -y A

[0042]

[0043] y A The vertical coordinate of the parking starting point, x C The x-coordinate of the parking endpoint is a known value.

[0044] The beneficial effects of this invention are as follows: Based on the two-segment circular arc planning of the rear parking trajectory of a vehicle in a vertical parking space, under the condition of satisfying boundary constraints and collision avoidance constraints, this invention adaptively calculates the pose at the tangent point of the two circular arc trajectories and the parameters of the two circular arc trajectories according to the relative position relationship between the initial position of the vehicle and the boundary obstacles, thereby maximizing the use of the parking opposite space and the parking space space. This not only effectively widens the initial feasible area for parking, but also effectively reduces the number of times the vehicle zigs through the parking space, resulting in better ride comfort. Attached Figure Description

[0045] Figure 1 This is a flowchart illustrating the perpendicular parking method of the present invention.

[0046] Figure 2 This is a schematic diagram of the parking kinematics model of the present invention;

[0047] Figure 3 This is a schematic diagram of the parking partial coordinate system of the present invention;

[0048] Figure 4 This is a schematic diagram illustrating the calculation of the lower limit of the vertical coordinate of the parking starting point according to the present invention;

[0049] Figure 5 This is a schematic diagram illustrating the calculation of the upper limit value of the vertical coordinate of the parking starting point according to the present invention;

[0050] Figure 6 This is a schematic diagram of the effective range of the parking starting point of the present invention;

[0051] Figure 7 This is a schematic diagram of the two-segment circular arc trajectory planning of the present invention;

[0052] Figure 8 This is a schematic diagram of the parking trajectory when the parking starting point is close to the boundary of the parking space entrance according to the present invention;

[0053] Figure 9 This is a schematic diagram of the parking trajectory when the parking starting point of the present invention is close to the boundary of the opposite lane. Detailed Implementation

[0054] The embodiments of the present invention are described in detail below with reference to the accompanying drawings. The drawings are for reference and illustration only and do not constitute a limitation on the scope of protection of the present invention.

[0055] In the process described in the specification, claims, or drawings of this invention, each step is numbered (e.g., step 10, 20, etc.). These numbers are used only to distinguish the steps and do not represent any execution order. It should be noted that the terms "first," "second," etc., used herein are only for distinguishing the objects being described and do not represent a chronological order, nor do they indicate that "first," "second," etc., are different types.

[0056] like Figure 1 As shown, this embodiment provides a method for parking in a perpendicular parking space, including:

[0057] Step 1: Establish a parking kinematics model based on the Ackermann steering model.

[0058] Figure 2 This is a schematic diagram of the parking kinematics model of the present invention, where θ is the vehicle heading angle. To determine the equivalent front wheel steering angle, the coordinates of the rear axle center point R are (x... r ,y r L is the wheelbase between the front and rear axles. f For the front overhang length, Lr For rear overhang length, W v The width of the vehicle.

[0059] The parking condition is a low-speed condition with no wheel slippage, and the center point R of the rear axle of the vehicle is used as the reference point.

[0060] Step 2: Obtain the coordinates of the target parking space, lane boundaries, obstacles, and the vehicle's position in the parking scene, and establish a local parking coordinate system based on the target parking space.

[0061] like Figure 3 As shown, in the parking scenario of this invention, the opposite lane of the parking space is a two-lane road, w in the figure. r For the width of the oncoming lane, w p For parking space width, L p The length of the parking space is V1 to V4, which are the outline points of the vehicle body, and P1 to P4 are the four corner points of the parking space.

[0062] In this embodiment, the horizontal axis of the parking local coordinate system is parallel to the parking space entrance line P1P2, and the vertical axis is perpendicular to the parking space entrance line P1P2.

[0063] Step 3: Determine the effective range of the parking starting point that satisfies the two-segment parking trajectory.

[0064] In this embodiment, step 3 includes:

[0065] Step 301: Determine the lower limit value y of the ordinate of the parking starting point that satisfies the two-segment parking trajectory. A1 Upper limit value y A2 .

[0066] like Figure 4 As shown, in this embodiment, the lower limit value of the vertical coordinate y of the parking starting point is determined. A1 The method includes: in the first arc trajectory of the two-segment parking trajectory, setting the vehicle to satisfy the first relationship when it is in a first state, wherein the first state is when the line O1V3' connecting the right rear point V3 of the vehicle and the center O1 of the first arc trajectory is perpendicular to the parking space entrance line P1P2.

[0067] In this embodiment, the first relation is: y O1 -|O1V3'|>y P2 , where y O1 This represents the ordinate of the center O1 of the first circular arc trajectory, y p2 The vertical coordinate of the upper left corner point P2 of the target parking space is represented by |O1V3'|, and the length of the line connecting the right rear point V3 of the vehicle and the center O1 of the first arc trajectory when the vehicle is in the first state is represented by |O1V3'|.

[0068] In this embodiment, the lower limit value of the vertical coordinate of the parking starting point is y. A1Determined according to the following formula:

[0069]

[0070] Among them, y A1 The lower limit of the ordinate of the parking starting point, y p2 The ordinate of P2 represents the top left corner of the target parking space, s1 represents the safe distance between the vehicle and the lower boundary of the lane, and R represents the vertical coordinate of the target parking space. min W represents the minimum turning radius of this vehicle. v Indicates the width of this vehicle, L r This indicates the rear overhang length of the vehicle.

[0071] like Figure 5 As shown, in this embodiment, the upper limit value of the vertical coordinate y of the parking starting point is determined. A2 The method includes: in the second arc trajectory of the two-segment parking trajectory, setting a second relation to satisfy when the vehicle is in a second state, wherein the second state is that the line O2V1' connecting the left front point V1 of the vehicle and the center O2 of the second arc trajectory is perpendicular to the opposite boundary.

[0072] In this embodiment, the second relation is: y O2 +|O2V1'| <y P1 +w r θ1>θ3

[0073] Among them, y O2 The y-coordinate represents the center O2 of the second circular arc trajectory. p1 The w represents the ordinate of the top right corner P1 of the target parking space. r The width of the oncoming lane is represented by |O2V1'|, which represents the length of the line connecting the front left point V1 of the vehicle and the center O2 of the second arc trajectory when the vehicle is in the second state. θ1 represents the central angle of the first trajectory segment, and θ3 represents the decision angle, which is determined according to the following formula:

[0074]

[0075] L represents the wheelbase of this vehicle. f W indicates the front overhang length of this vehicle. v Indicates the width of this vehicle, R min This indicates the vehicle's minimum turning radius.

[0076] In this embodiment, the upper limit value of the vertical coordinate y of the parking starting point is... A2 Determined according to the following formula:

[0077]

[0078] Among them, y A2The y-coordinate of the parking starting point represents the upper limit of the coordinate. p1 The w represents the ordinate of the top right corner P1 of the target parking space. r R indicates the width of the oncoming lane. min s2 represents the minimum turning radius of the vehicle, s2 represents the safe distance between the vehicle and the upper boundary of the lane, and L represents the track width of the vehicle. f W indicates the front overhang length of this vehicle. v This indicates the width of the vehicle.

[0079] Step 302: Based on the lower limit value y of the ordinate of the parking starting point of the parking trajectory... A1 Upper limit value y A2 In the parking local coordinate system, draw the upper limit cutoff line Line1 and the lower limit cutoff line Line2 of the parking starting point. The range determined by the upper limit cutoff line and the lower limit cutoff line is the effective range of the parking starting point.

[0080] like Figure 6 As shown, after passing through the upper limit value y A2 Lower limit value y A1 The area between Line1 and Line2, which are parallel to the horizontal axis of the parking local coordinate system, is the effective range of the parking starting point.

[0081] Step 4: Determine whether the vehicle's current position is within the valid range of the parking starting point. If yes, proceed to the next step; otherwise, determine that the vehicle's current position cannot be used for two-stage parking and return to Step 2.

[0082] Step 5: Calculate the pose of the trajectory switching point based on the initial parking position, the coordinates of the target parking space, and the width of the opposite lane, and calculate the parameters of the two arc trajectories based on the pose of the trajectory switching point.

[0083] The two-segment circular arc trajectory planning of the present invention is as follows: Figure 7 As shown, point A is the parking start point, point B is the trajectory switching point, and point C is the parking end point. The vehicle's heading angle at points A, B, and C is denoted as θ. A θ B θ C To reduce planning complexity, the radii of both circular arc trajectories are the vehicle's minimum turning radius R. min .

[0084] In this embodiment, step 5 includes:

[0085] Step 501: Control the vehicle to drive to parking starting point A, and control the initial heading angle of the vehicle to 0.

[0086] If the starting parking point does not coincide with the parking start point A, then control the vehicle to move in a straight line to the parking start point position.

[0087] Step 502: Based on the distance from the parking starting point A to the opposite boundary of the target parking space, adaptively determine the length of the first arc trajectory AB, and control the vehicle to stop after traveling to the trajectory switching point B.

[0088] It is easy to understand that the length of the first arc trajectory AB in this embodiment is determined by its corresponding central angle θ1.

[0089] Step 503: Switch the vehicle to reverse gear and turn the steering wheel to its limit in the opposite direction. Control the vehicle to reverse along the second arc trajectory into the parking endpoint C of the target parking space.

[0090] In this embodiment, the x-coordinate of the parking endpoint C is the coordinate of the midpoint between the upper left corner point P4 and the upper right corner point P1 of the target parking space.

[0091] In this embodiment, the coordinates of the parking start point A, trajectory switching point B, parking end point C, and the vehicle's heading angle at the above locations are determined according to the following formula:

[0092] x A =x C +R min (1-cosθ2-sinθ1)

[0093] x B =x C +R min (1-cosθ2)

[0094] y B =y A +R min (1-cosθ1)

[0095] y C =y A +R min (1-cosθ1-sinθ2)

[0096]

[0097] θ2=π / 2-θ1

[0098] θ A =0,θ B =θ1,θ C =π / 2

[0099] in:

[0100] m = y P1 +W r -s2-R min -y A

[0101]

[0102] The ordinate y of the parking starting point A A x-coordinate of the parking endpoint C C The value is known.

[0103] This step allows for the following: if the parking starting point is closer to the target parking space, the vehicle's direction can be adjusted as much as possible within the first arc trajectory using the opposing space; if the parking starting point is closer to the opposing boundary, the vehicle's position can be adjusted as much as possible within the second arc trajectory using the space between the vehicle and the parking space entrance, as well as the internal space of the target parking space.

[0104] Figure 8 , Figure 9 The diagrams show extreme conditions at the starting point of parking, near the boundary of the parking space entrance and at the boundary of the opposite lane. As can be seen from the changes in the vehicle body profile, no collision occurred during the entire parking process, and the vehicle ultimately stopped in the target parking space with the correct body posture.

[0105] The above-disclosed embodiments are merely preferred embodiments of the present invention and should not be construed as limiting the scope of protection of the present invention. Therefore, any equivalent variations made in accordance with the claims of the present invention are still within the scope of the present invention.

Claims

1. A method for parking in a perpendicular parking space, characterized in that, include: Step 1: Establish a parking kinematics model based on the Ackermann steering model; Step 2: Obtain the coordinates of the target parking space, lane boundaries, obstacles, and the vehicle's position in the parking scenario, and establish a local parking coordinate system based on the target parking space; Step 3: Determine the effective range of the parking starting point that satisfies the two-segment parking trajectory; Step 4: Determine whether the vehicle's current position is within the effective range of the parking starting point. If yes, proceed to the next step; otherwise, determine that the vehicle's current position cannot be used for two-stage parking and return to step 2. Step 5: Calculate the pose of the trajectory switching point based on the initial parking position, the coordinates of the target parking space, and the width of the opposite lane, and calculate the parameters of the two arc trajectories based on the pose of the trajectory switching point. Step 3 includes: Step 301: Determine the lower and upper limits of the ordinate of the starting point of the parking trajectory that satisfies the two-segment parking trajectory. Step 302: Based on the lower limit and upper limit of the ordinate of the parking starting point of the parking trajectory, draw the upper limit cutoff line and the lower limit cutoff line of the parking starting point in the local parking coordinate system, respectively. The range determined by the upper limit cutoff line and the lower limit cutoff line of the parking starting point is the effective range of the parking starting point. The method for determining the lower limit of the vertical coordinate of the parking starting point includes: in the first arc trajectory of the two-segment parking trajectory, setting the first relationship when the vehicle is in a first state, wherein the first state is when the line connecting the right rear point of the vehicle and the center of the first arc trajectory is perpendicular to the parking space entrance line. The first relation is: y O1 -|O2V1'|> y P2 ,in, y O1 This represents the ordinate of the center O1 of the first circular arc trajectory. y p2 The vertical coordinate of the upper left corner point P2 of the target parking space is represented by |O1V3'|, which represents the length of the line connecting the right rear point V3 of the vehicle and the center O1 of the first arc trajectory when the vehicle is in the first state. The lower limit of the ordinate of the parking starting point is determined according to the following formula: in, y A1 This represents the lower limit of the ordinate of the parking starting point. y p2 The ordinate of P2 represents the top left corner of the target parking space, s1 represents the safe distance between the vehicle and the lower boundary of the lane, and R represents the vertical coordinate of the target parking space. min This indicates the vehicle's minimum turning radius. W v This indicates the width of the vehicle. L r This indicates the rear overhang length of the vehicle.

2. The perpendicular parking method according to claim 1, characterized in that, The method for determining the upper limit of the longitudinal coordinate of the parking starting point includes: in the second arc trajectory of the two-segment parking trajectory, setting a second relational expression to be satisfied when the vehicle is in a second state, wherein the second state is that the line connecting the left front point of the vehicle and the center of the second arc trajectory is perpendicular to the opposite boundary.

3. The perpendicular parking method according to claim 2, characterized in that, The second relation is: y O2 +|O2V1'|< y P1 + w r , θ 1> θ 3, in, y O2 This represents the ordinate of the center O2 of the second circular arc trajectory. y p1 This represents the ordinate of the top right corner P1 of the target parking space. w r This indicates the width of the oncoming lane. |O2V1'| represents the length of the line connecting the front left point V1 of this vehicle and the center O2 of the second arc trajectory when this vehicle is in the second state. θ 1 represents the central angle of the first segment of the trajectory. θ 3 represents the judgment angle, the judgment angle is... θ 3. Determined according to the following formula: L This indicates the wheelbase of the vehicle. L f This indicates the length of the front overhang of the vehicle. W v Indicates the width of this vehicle, R min This indicates the vehicle's minimum turning radius.

4. The perpendicular parking method according to claim 3, characterized in that, The upper limit of the vertical coordinate of the parking starting point is determined according to the following formula: in, y A2 This represents the upper limit of the vertical coordinate of the parking starting point. y p1 This represents the ordinate of the top right corner P1 of the target parking space. w r R indicates the width of the oncoming lane. min s1 represents the vehicle's minimum turning radius, and s2 represents the safe distance between the vehicle and the upper boundary of the lane. L This indicates the wheelbase of the vehicle. L f This indicates the length of the front overhang of the vehicle. W v This indicates the width of the vehicle.

5. The perpendicular parking method according to claim 1, characterized in that, Step 5 includes: Step 501: Control the vehicle to drive to the parking starting point and control the initial heading angle of the vehicle to 0. Step 502: Adaptively determine the length of the first arc trajectory based on the distance from the parking starting point to the opposite boundary of the target parking space, and control the vehicle to stop after it reaches the trajectory switching point; Step 503: Switch the vehicle to reverse gear and turn the steering wheel to its limit in the opposite direction. Control the vehicle to reverse along the second arc trajectory into the parking end point of the target parking space.

6. The perpendicular parking method according to claim 5, characterized in that, The coordinates of the parking start point, trajectory switching point, and parking end point, as well as the vehicle's heading angle at the above locations, are determined according to the following formula: x A = x C + R min (1-cosθ2-sinθ1) x B = x C + R min (1-cosθ2) y B = y A + R min (1-cosθ1) y C = y A + R min (1-cosθ1-sinθ2) θ 2=π / 2- θ 1 θ A =0, θ B = θ 1, θ C =π / 2 in: x A The x-coordinate of the parking starting point. y A The vertical coordinate represents the starting point of the parking space. x B The x-coordinate of the trajectory switching point. y B The ordinate of the trajectory switching point. x C The x-coordinate represents the endpoint of the parking maneuver. y C The vertical coordinate represents the endpoint of the parking space. R min This indicates the vehicle's minimum turning radius. y P1 This represents the ordinate of the top right corner of the target parking space. θ A The vehicle heading angle indicating the starting point of parking. θ B The vehicle heading angle at the trajectory switching point. θ C The vehicle's heading angle, indicating the end point of parking. W r Indicates the width of the oncoming lane. W v This indicates the width of the vehicle. s 2 indicates the safe distance between the vehicle and the upper boundary of the lane. L This indicates the wheelbase of the vehicle. L f This indicates the front overhang length of the vehicle.

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