New vehicle control method based on "polyline" path

Abstract

A new vehicle control method based on a "polyline" path. For vehicle control in a "polyline" path scene, the present method provides a new vehicle control method in the "polyline" path scene. According to the method, traveling directions of a vehicle in path segments can be automatically planned on the basis of a passing point set of path planning, so that a traveling posture of the vehicle is determined; on the basis of the traveling posture, acceleration and deceleration control is performed on the route, so that the longitudinal linear speed of each segment can be well automatically adjusted; and on the basis of the traveling posture, the vehicle rotates around the geometric center of the vehicle at a "polyline" vertex, so that the error is reduced to the maximum extent, ensuring the precision of a subsequent straight path segment.

Description

A new vehicle control method based on "broken line" path Technical Field

[0001] The present invention belongs to the technical field of automatic control, and in particular relates to a new vehicle control method based on a "broken line" path. Background Art

[0002] Autonomous control of lawn mowers, warehouse logistics vehicles, agricultural machinery, and other vehicles requires answering three fundamental questions: Where am I? Where am I going? How do I get there? Lateral and longitudinal control of the vehicle falls under the purview of the third question. Different lateral and longitudinal control methods are required for different scenarios. Among these, there is a category of lateral and longitudinal control for "zigzag" path scenarios, which has a wide range of applications. Currently, there are two extremes in lateral and longitudinal control for this scenario. The first extreme is that lateral control is relatively detailed, but longitudinal control is less comprehensive. Compared to autonomous driving (or assisted driving) that only considers lateral control, the quality of longitudinal control in this type of unmanned driving significantly impacts both overall control performance and the vehicle's service life. The second extreme is that lateral and longitudinal control methods are often applied to passenger vehicles. However, passenger vehicles operate in completely unstructured scenarios, with different control priorities and significant variations in controller performance. Therefore, selecting the appropriate lateral and longitudinal control method for "zigzag" path scenarios is particularly important.

[0003] Unlike the control focus of autonomous passenger cars, control accuracy is often a crucial metric in structured or semi-structured "zigzag" path scenarios. An error of around 30 centimeters in passenger cars is insufficient for practical use. Without refined longitudinal control, maintaining accuracy near the "inflection points" along these "zigzag" paths is difficult. Furthermore, considering requirements like obstacle avoidance, these "inflection points" often require even higher accuracy.

[0004] Therefore, in the process of vehicle control on a "zigzag" path, how to improve the accuracy of longitudinal control and "inflection point" control is a hot topic and pain point in current industry research.

[0005] Summary of the Invention

[0006] In order to solve the above technical problems, we propose a new vehicle control method based on "broken line" path for vehicle control in the "broken line" path scenario.

[0007] The present invention provides the following technical solutions:

[0008] A new vehicle control method based on a "broken line" path includes the following steps:

[0009] S100: Acquire real-time position information of the vehicle;

[0010] S200: Calculating the driving direction of the path segment based on the passing point set;

[0011] S300: Calculating the longitudinal linear velocity of the path segment based on the passing point set;

[0012] S400: Calculate the angular velocity at the “inflection point”;

[0013] S500: Calculate the angular velocity of the path segment.

[0014] Preferably, the vehicle is controlled in real time by the longitudinal linear velocity of the path segment, the angular velocity of the path segment and the angular velocity at the "inflection point".

[0015] Preferably, in step S100, the real-time position information of the vehicle is obtained by installing a GNSS antenna on the vehicle.

[0016] Preferably, in step S200,

[0017] The set of passing points of the planned vehicle is S i (x i ,y i ),i=1,2,...,N,x i ,y i are the x-coordinate component and y-coordinate component of the origin of the vehicle coordinate system in the world coordinate system respectively;

[0018] Then the point set contains N-1 path segments in total. For the i-th path segment, its path inclination angle θ is i is θ i =a tan 2(Δy i ,Δx i )=a tan 2(y i+1 -y i ,x i+1 -x i ), i=1,2,...,N-1;

[0019] Let Δθ i =θ i -θ i-1 , i=2,3,...,N-1, then

[0020] Based on the driving direction of the first path segment, the driving direction d of each path segment can be recursively determined i ,

[0021] Preferably, in step S300,

[0022] The set of passing points of the planned vehicle is S i (x i ,yi ),i=1,2,...,N,x i ,y i are the x-coordinate component and y-coordinate component of the origin of the vehicle coordinate system in the world coordinate system,

[0023] Then the point set contains N-1 path segments in total. For the i-th path segment, its path inclination angle θ is i for

[0024] θ i =a tan 2(Δy i ,Δx i )=a tan 2(y i+1 -y i ,x i+1 -x i ), i=1,2,...,N-1;

[0025] S i (x i ,y i ), i=1,2,...,N-1 is the origin, S i (x i ,y i ) points to S i+1 (x i+1 ,y i+1 ) is the positive of X axis, and Y is determined to be positive in accordance with the right-hand rule, and the path coordinate system F is established. i , according to the current position of the vehicle is P0(x0,y0,θ0), according to the plane coordinate conversion formula:

[0026] The vehicle is in the path coordinate system F i The x coordinate under is x 0i , the y coordinate is y 0i , the posture is θ 0i ;

[0027] x 0i Indicates that the vehicle starts from the starting point S i (x i ,y i ) Drive to the target point S i+1 (x i+1 ,y i+1 ) in the process of the current point P0 (x0, y0, θ0) and the starting point S i (x i ,y i ) in the path segment S i S i+1 The projection on

[0028] xx 0iIndicates that the vehicle starts from the starting point S i (x i ,y i ) Drive to the target point S i+1 (x i+1 ,y i+1 ) in the process of the current point P0 (x0, y0, θ0) and the target point S i+1 (x i+1 ,y i+1 ) in the path segment S i S i+1 The projection on

[0029] Order xx 0i =||S i S i+1 ||-x 0i ,but

[0030] Among them, the pose of the current point P0: x0-x coordinate value in the world coordinate system, y0-y coordinate value in the world coordinate system; θ0-the inclination angle of the vehicle coordinate system (with the geometric center of the vehicle as the origin and the direction of the vehicle head as the positive X axis, in accordance with the right-hand rule) in the world coordinate system, that is, the current posture of the vehicle;

[0031] ||S i S i+1 ||: Starting point S i With the target point S i+1 the distance between them;

[0032] Among them, v start : Starting speed, |Δθ i |≤θ min , v start =v is ;|Δθ i |>θ min , v start is the set value;

[0033] θ min The angle difference between the set same-direction path segments is theoretically 0, but actually is a smaller value of 1;

[0034] d a : acceleration distance, when ‖S i S i+1 ‖≤d a +d d , d a =0.5||S i S i+1 ||;||S i S i+1 ||>d a +dd , d a is the set value;

[0035] v is : set speed on the i-th path segment;

[0036] Among them, v tmp : intermediate variable; |Δθ i+1 |≤θ min , v tmp =v i+1,s ;|Δθ i+1 |>θ min , v tmp is the set value;

[0037] d d :Deceleration distance, when ||S i S i+1 ||≤d a +d d , d d =0.5||S i S i+1 ||;||S i S i+1 ||>d a +d d , d d is the set value;

[0038] d min : The longitudinal distance threshold for switching between path segments. The theoretical value is 0, but it is actually set to a smaller value.

[0039] Absolute value of longitudinal linear velocity

[0040] Longitudinal linear velocity v i =v i 'd i .

[0041] Preferably, in step S400,

[0042] Let the angle difference Δθ v0 =θ vi -θ0, then

[0043] Unlimited angular velocity

[0044] Among them, k b : Large angle difference rotation coefficient, which is the set value;

[0045] θ b : Large angle error threshold, which is the set value;

[0046] k s : Small angle difference rotation coefficient, which is the set value;

[0047] θ s : Small angle error threshold, which is the set value;

[0048] Among them, ω min : Minimum rotation angular velocity, which is the set value;

[0049] ω max : Maximum rotation angular velocity, which is the set value.

[0050] Preferably, in the step S500, according to the y in the step S200 0i and θ 0i ,y 0i This is the lateral position deviation at this time, θ 0i This is the yaw angle deviation at this time; combined with the lateral control algorithm, the angular velocity ω of the path segment is obtained mi .

[0051] Preferably, the lateral control algorithm is any one of pure tracking, front axle feedback, rear axle feedback, LQR and MPC.

[0052] Compared with the existing technology, the beneficial effects of the present invention are: it can realize the autonomous judgment of the driving direction in the path segment under the "broken line" path scenario; it can realize the calculation of the longitudinal linear velocity in the path segment under the "broken line" path scenario; it can realize the calculation of the angular velocity at the "inflection point" under the "broken line" path scenario; the present application can automatically plan the driving direction of the vehicle in each path segment according to the passing point set of the path planning, thereby determining the driving posture of the vehicle; based on the driving posture, acceleration and deceleration control is performed on the route, which can automatically adjust the longitudinal linear velocity of each segment; based on the driving posture, at the "inflection point", the vehicle rotates around its own geometric center to minimize errors to ensure the accuracy of subsequent straight path segments. BRIEF DESCRIPTION OF THE DRAWINGS

[0053] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention and do not constitute a limitation of the present invention. In the accompanying drawings:

[0054] FIG1 is a schematic flow diagram of the present invention. DETAILED DESCRIPTION

[0055] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0056] The present invention provides a technical solution, and the specific flow chart is shown in FIG1 . The specific execution process of the method is as follows.

[0057] A GNSS antenna must be installed on the vehicle to obtain the vehicle's real-time position information.

[0058] 1. Calculate the driving direction of each path segment based on the passing point set

[0059] 1.1 Calculation of path inclination angle θ i : In the planning module, the set of passing points of the planned vehicle is S i (x i ,y i ),i=1,2,...,N,x i ,y i are the x-coordinate component and y-coordinate component of the origin of the vehicle coordinate system in the world coordinate system respectively;

[0060] Then the point set contains N-1 path segments in total. For the i-th path segment, its path inclination angle θ is i for

[0061] θ i =a tan 2(Δy i ,Δx i )=a tan 2(y i+1 -y i ,x i+1 -x i ), i=1,2,...,N-1;

[0062] 1.2 Determining whether the driving direction has changed: In this structured or semi-structured scenario, considering the friction damage to the vehicle and the ground when rotating around its own geometric center, the angle of rotation of the vehicle around itself should be as small as possible between two path segments. Based on this principle, let Δθ i =θ i -θ i-1 , i=2,3,...,N-1, then

[0063] 1.3 Recursively determine the driving direction of each path segment: Based on the driving direction of the first path segment, the driving direction of each path segment can be recursively determined. i ,

[0064] 2. Calculate the longitudinal linear velocity on the path segment based on the passing point set

[0065] 2.1 Calculation of path inclination angle θ i : In the planning module, the set of passing points of the planned vehicle is S i (x i ,y i ),i=1,2,...,N,x i ,y i They are the x-coordinate component and y-coordinate component of the origin of the vehicle coordinate system in the world coordinate system.

[0066] Then the point set contains N-1 path segments in total. For the i-th path segment, its path inclination angle θ is i for

[0067] θ i =a tan 2(Δy i ,Δx i )=a tan 2(y i+1 -y i ,x i+1 -x i ), i=1,2,...,N-1;

[0068] 2.2 Obtaining the path coordinate system F i The pose of the current point P0′(x 0i ,y 0i ,θ 0i )

[0069] Then S i (x i ,y i ), i=1,2,...,N-1 is the origin, S i (x i ,y i ) points to S i+1 (x i+1 ,y i+1 ) is the positive of X axis, and Y is determined to be positive in accordance with the right-hand rule, and the path coordinate system F is established. i , assuming that the current position of the vehicle is P0(x0,y0,θ0), according to the plane coordinate conversion formula

[0070] The vehicle is in the path coordinate system F i The x coordinate under is x 0i , the y coordinate is y 0i , the posture is θ 0i In fact, y 0i This is the lateral position deviation at this time, θ 0i This is the yaw angle deviation at this time;

[0071] 2.3 Obtain the pose of the current point P0(x0,y0,θ0) and the starting point S i (x i ,y i ) and the pose of the current point P0(x0,y0,θ0) and the target point S i+1 (x i+1 ,y i+1 ) on the path segment x 0i , xx 0i :

[0072] x 0i Indicates that the vehicle starts from the starting point S i (x i ,y i ) Drive to the target point S i+1 (x i+1 ,y i+1 ) in the process of the current point P0 (x0, y0, θ0) and the starting point S i (x i ,y i ) in the path segment S i S i+1 The projection on

[0073] xx 0i Indicates that the vehicle starts from the starting point S i (x i ,y i ) Drive to the target point S i+1 (x i+1 ,y i+1 ) in the process of the current point P0 (x0, y0, θ0) and the target point S i+1 (x i+1 ,y i+1 ) in the path segment S i S i+1 The projection on

[0074] Order xx 0i =||S i S i+1 ||-x 0i ,but

[0075] Among them, the pose of the current point P0: x0-x coordinate value in the world coordinate system, y0-y coordinate value in the world coordinate system; θ0-the inclination angle of the vehicle coordinate system (with the geometric center of the vehicle as the origin and the direction of the vehicle head as the positive X axis, in accordance with the right-hand rule) in the world coordinate system, that is, the current posture of the vehicle;

[0076] ||S i S i+1||: Starting point S i With the target point S i+1 the distance between them;

[0077] 2.4 Based on x 0i Calculate the longitudinal linear velocity v during the acceleration phase ia :

[0078] Among them, v start : Starting speed, |Δθ i |≤θ min , v start =v is ;|Δθ i |>θ min , v start is the set value;

[0079] θ min The angle difference between the set same-direction path segments is theoretically 0, but actually is a smaller value of 1;

[0080] d a : acceleration distance, when ‖S i S i+1 ‖≤d a +d d , d a =0.5||S i S i+1 ||;||S i S i+1 ||>d a +d d , d a is the set value;

[0081] v is : set speed on the i-th path segment;

[0082] 2.5 Based on xx 0i Calculate the longitudinal linear velocity v during the deceleration phase id :

[0083] Among them, v tmp : intermediate variable; |Δθ i+1 |≤θ min , v tmp =v i+1,s ;|Δθ i+1 |>θ min , v tmp is the set value;

[0084] d d :Deceleration distance, when ||S i S i+1 ||≤d a+d d , d d =0.5||S i S i+1 ||;||S i S i+1 ||>d a +d d , d d is the set value;

[0085] d min : The longitudinal distance threshold for switching between path segments. The theoretical value is 0, but it is actually set to a smaller value.

[0086] 2.6 Determine the longitudinal velocity v i

[0087] Absolute value of longitudinal linear velocity

[0088] Longitudinal linear velocity v i =v i 'd i .

[0089] 3. Calculate the angular velocity at the "inflection point"

[0090] 3.1 Calculate the desired posture θ of the vehicle vi

[0091] 3.2 Calculate the vehicle's angular velocity ω ei

[0092] Let the angle difference Δθ v0 =θ vi -θ0, then

[0093] Unlimited angular velocity

[0094] Among them, k b : Large angle difference rotation coefficient, which is the set value;

[0095] θ b : Large angle error threshold, which is the set value;

[0096] k s : Small angle difference rotation coefficient, which is the set value;

[0097] θ s : Small angle error threshold, which is the set value;

[0098] Among them, ω min : Minimum rotation angular velocity, which is the set value;

[0099] ω max: Maximum rotation angular velocity, which is the set value.

[0100] 4. Calculate the angular velocity of the path segment

[0101] With the lateral position deviation y at 2.2 0i , yaw angle deviation θ 0i , the angular velocity ω in the path segment can be obtained according to the common lateral control algorithm mi .

[0102] Common lateral control algorithms include pure tracking, front axle feedback, rear axle feedback, LQR, and MPC. The first two are control laws based on vehicle geometric constraints, while rear axle feedback is a control law derived from the Lyapunov stability criterion. LQR (Linear Quadratic Regulator) and MPC (Model Predictive Control) are two commonly used methods for solving first-order linear state equations. The former is a full-state feedback control, while the latter is a rolling optimization control. Both are based on minimizing the weighted cost function of the state vector and the input as the optimization objective to find the optimal control solution.

[0103] 5. Real-time vehicle control based on calculation results

[0104] In this embodiment, the vehicle is equipped with a GNSS antenna to obtain real-time posture information of the vehicle. After the steps in the control process of this application, the angular velocity at the "inflection point", the longitudinal linear velocity of the path segment and the angular velocity of the path segment are calculated. The vehicle is controlled in real time based on the obtained angular velocity at the "inflection point", the longitudinal linear velocity of the path segment and the angular velocity of the path segment, thereby realizing lateral and longitudinal control at the path segment and refined control at the "inflection point".

[0105] It should be noted that, in this document, relational terms such as first and second, etc., are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "comprises," "comprising," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that includes a list of elements includes not only those elements but also other elements not explicitly listed, or elements inherent to such process, method, article, or apparatus.

[0106] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art will be able to modify the technical solutions described in the aforementioned embodiments or substitute equivalents for some of the technical features. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

Claims

1. A new vehicle control method based on a "broken line" path, characterized in that, Including the following steps: S100: Obtain the real-time pose information of the vehicle; S200: Calculate the driving direction of the path segment based on the point set; S300: Calculate the longitudinal linear velocity of the path segment based on the point set; S400: Calculate the angular velocity at the "inflection point"; S500: Calculate the angular velocity of the path segment.

2. A new vehicle control method based on a "broken line" path according to claim 1, characterized in that, Perform real-time control of the vehicle through the longitudinal linear velocity of the path segment, the angular velocity of the path segment, and the angular velocity at the "inflection point".

3. A novel vehicle control method based on a "broken line" path according to claim 1, characterized in that, In the step S100, the real-time pose information of the vehicle is obtained by installing a GNSS antenna on the vehicle.

4. A new vehicle control method based on a "broken line" path according to claim 1, characterized in that, In the step S200, The set of passing points of the planned vehicle is S i (x i , y i ), i = 1, 2,..., N, where x i , y i are the x - coordinate component and y - coordinate component of the origin of the vehicle coordinate system in the world coordinate system respectively; Then this point set contains a total of N - 1 path segments. For the i-th path segment, its path inclination angle θ i is θ i = a tan 2(Δy i , Δx i ) = a tan 2(y i+1 - y i , x i+1 - x i ), i = 1, 2,..., N - 1; Let Δθ i = θ i - θ i-1 , where i = 2, 3,..., N - 1, then Based on the driving direction of the first path segment, the driving direction d of each path segment can be recursively determined i , 5. A new vehicle control method based on a "broken line" path according to claim 1, characterized in that, In the step S300, The set of passing points of the planned vehicle is S i (x i ,y i ), i = 1, 2,..., N, x i ,y i are the x - coordinate component and y - coordinate component of the origin of the vehicle coordinate system in the world coordinate system respectively, Then the point set contains a total of N - 1 path segments. For the i-th path segment, its path inclination angle θ i is θ i = a tan 2(Δy i , Δx i ) = a tan 2(y i+1 - y i , x i+1 - x i ), i = 1, 2,..., N - 1; Taking S i (x i , y i ), i = 1, 2,..., N - 1 as the origin, taking S i (x i , y i ) pointing to S i+1 (x i+1 , y i+1 ) as the positive X-axis, determining the positive Y according to the right-hand rule, and establishing the path coordinate system F i . Given that the pose of the current point of the vehicle is P0(x0, y0, θ0), according to the plane coordinate transformation formula: It can be obtained that the vehicle is in the path coordinate system F i and the x coordinate under it is x 0i , the y coordinate is y 0i , and the attitude is θ 0i ; x 0i Indicates that the vehicle drives from the starting point S i (x i , y i ) towards the target point S i+1 (x i+1 , y i+1 ) during which the pose P0(x0, y0, θ0) of the current point and the starting point S i (x i , y i ) is the projection of the distance on the path segment S i S i+1 is as follows. xx 0i Indicates that the vehicle starts from the starting point S i (x i , y i ) and drives towards the target point S i+1 (x i+1 , y i+1 ), during which the pose P0(x0, y0, θ0) of the current point and the target point S i+1 (x i+1 , y i+1 ) is the projection of the distance on the path segment S i S i+1 . Let xx 0i = ||S i S i+1 || - x 0i then Wherein, the pose P0 of the current point: x0 - the x coordinate value in the world coordinate system, y0 - the y coordinate value in the world coordinate system; θ0 - the inclination angle of the vehicle coordinate system (with the geometric center of the vehicle as the origin, the front direction as the positive X axis, conforming to the right-hand rule) in the world coordinate system, that is, the current attitude of the vehicle; ||S i S i+1 ||: Starting point S i and the target point S i+1 The distance between; Among them, v start : starting speed, |Δθ i | ≤ θ min , v start = v is ; |Δθ i | > θ min , v start is the set value; θ min is the angular difference of the set same-direction path segments, theoretically 0 and actually a small value; d a : Acceleration distance, when ||S i S i+1 || ≤ d a +d d ,d a =0.5||S i S i+1 ||;||S i S i+1 || > d a +d d ,d a is a set value; v is : The set speed on the i-th path segment; where, v tmp : intermediate variable; |Δθ i+1 | ≤ θ min , v tmp = v i+1,s ; |Δθ i+1 | > θ min , v tmp is a set value; d d : Deceleration distance, when ||S i S i+1 || ≤ d a +d d ,d d = 0.5||S i S i+1 ||; ||S i S i+1 || > d a +d d ,d d is a set value; d min : The vertical distance threshold for switching between path segments, with a theoretical value of 0 and an actual value set to a relatively small value; Absolute value of the longitudinal linear velocity Longitudinal linear velocity v i = v i 'd i .

6. A new vehicle control method based on a "broken line" path according to claim 1, characterized in that, In the described step S400, Let the angular difference be Δθ v0 = θ vi - θ0, then Unrestricted angular velocity where k b : the large angular difference rotation coefficient, which is a set value; θ b : Large angle error threshold, which is a set value; k s : The small angular difference rotation coefficient, which is a set value; θ s : Small angle error threshold, which is a set value; where ω min : the minimum rotational angular velocity, which is a set value; ω max : The maximum rotational angular velocity, which is a set value.

7. A novel vehicle control method based on a "broken line" path according to claim 1, characterized in that, In the said step S500, according to y in S200 0i and θ 0i , y 0i is the lateral position deviation at this time, and θ 0i is the yaw angle deviation at this time; combining with the lateral control algorithm, the angular velocity ω mi of the path segment is obtained.

8. A novel vehicle control method based on a "broken line" path according to claim 7, characterized in that, The lateral control algorithm is any one of pure tracking, front axle feedback, rear axle feedback, LQR, and MPC.

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