Lane centering driving control method and system

Abstract

The invention provides a lane centering driving control method and system, and the method comprises the steps: building a lane line geometric model through the perception capability of a camera, obtaining a steering wheel angle needed for passing a curve according to the vehicle wheelbase, the vehicle speed, the lane line radius and the transverse distance of a preview point, and carrying out the feedforward calculation, according to the lateral deviation and the course deviation of the vehicle and the lane line, a required lateral deviation compensation rotation angle and a course deviation compensation rotation angle are obtained, namely feedback calculation is carried out, finally, a total steering wheel rotation angle is obtained through calculation in combination with a feedforward and feedback algorithm, the lane line on the other side is virtualized when the vehicle enters a two-in-one scene or a one-in-two scene, and therefore the vehicle can enter the two-in-one scene or a one-in-two scene. A safe driving track is planned, a vehicle is smoothly controlled to enter a new lane in the middle, connection between lane lines is seamlessly achieved, and the situation that a driver frequently takes over the vehicle, and the driving experience is affected is avoided; and meanwhile, driving risks caused by line pressing and line riding of the vehicle are avoided.

Description

Technical Field

[0001] The present invention relates to the field of vehicle electronics technology, and specifically, to a lane centering driving control method and system. Background Art

[0002] Currently, information technologies represented by high-precision sensors, high-computing power chips, Internet of Things, cloud computing, big data, and artificial intelligence are widely used, accelerating the intelligent development of society. The intelligent process in the field of vehicle traffic has also evolved accordingly. Among them, ADAS / AD (Advanced Driver Assistance System / Autonomous Driving) is a key innovation area in the vehicle industry.

[0003] During the evolution of ADAS (Advanced Driver Assistance System) to AD (Autonomous Driving), various sub-functions emerge in an endless stream (from concept proposal to function implementation), such as ACC (Adaptive Cruise Control), LKA (Lane Keeping Assistance), LDW (Lane Departure Warning), TJA / ICA (Traffic Jam Assist / Integrated Cruise Assist), etc. In the traditional LKA function, when passing through a one-lane-to-two-lanes or two-lanes-to-one-lane road, generally one of the following two strategies is adopted: ① The LKA function directly exits and is taken over by the driver (one-lane-to-two-lanes road). ② Virtual lane lines, and continue to drive forward for 1 second to 2 seconds (two-lanes-to-one-lane road). For strategy ①, the superiority of assisted driving is not reflected; for strategy ②, it is possible that the function exits during the process of passing through an intersection, or when entering a new lane, there is a situation of crossing the line / riding the line. Therefore, there is an urgent need for a method to enrich the traditional LKA function and improve the driving experience, so as to reasonably control the vehicle to drive within the lane. Summary of the Invention

[0004] Aiming at the defects in the prior art, the purpose of the present invention is to provide a lane centering driving control method and system. In a two-lanes-to-one-lane or one-lane-to-two-lanes scenario, based on the lane line geometric model, a virtual lane line on one side is created, and the feedforward-feedback algorithm is used to control the lateral operation of the vehicle, so that the vehicle smoothly and centrally enters the new lane.

[0005] To achieve the above technical effects, the present invention adopts the following technical solutions:

[0006] According to the first aspect of the present invention, a lane centering driving control method is provided, including the following steps: Step S1. Taking the vehicle centroid as the origin of the coordinate system, the forward direction of the vehicle as the x-axis, and the lateral direction of the vehicle as the y-axis, a vehicle coordinate system is established. The vehicle front camera continuously collects the information of the front lane lines, obtains the lateral offset distance C0, lane line heading angle C1, and lane line curvature C2 of each lane line in the vehicle coordinate system, and based on the above parameters, a geometric model of the lane line is established in the vehicle coordinate system: Among them, the variable x represents the distance along the forward direction of the vehicle (unit: meter); y represents the distance in the lateral direction of the vehicle (unit: meter), representing the lateral offset of the lane line relative to the vehicle's center of mass. The model is used to describe the shape of the lane line in real time as the vehicle moves forward;

[0007] Step S2. Calculate the change in the heading angle ΔC1 and the change in curvature ΔC2 of the lane lines on both sides of the vehicle in real time. When one side of the lane line disappears and at the same time |ΔC1| > 0.08 or |ΔC2| > 0.01 of the lane line on the other side is detected, it is determined that the vehicle has entered the one-lane-splits-into-two / two-lanes-merge-into-one scenario;

[0008] Step S3. Generate a virtual lane line in the vehicle coordinate system based on C0 of the originally disappeared lane line, C1 and C2 of the lane line on the other side of the vehicle, and the lane line geometric model established in Step S1; calculate the virtual lane line duration Ti according to the real-time vehicle speed V: Ti = 2.5 - V / 120, where Ti ∈ [1.5, 2.5] seconds and V is the real-time vehicle speed, unit: Km / h; within the time Ti, if it is recognized that the length L of the new lane line ≥ 20 + 40*(2.5 - Ti) meters, it is determined that the new lane line has an effective length, and Step 4 is executed, otherwise, the driver is prompted to take over the vehicle;

[0009] Step S4. Within the virtual lane line duration Ti, execute the feedforward-feedback control algorithm, including: S4.1 Feedforward control: Calculate the front wheel steering angle δ through the following formula: , where L is the wheelbase of the vehicle; e is the lateral distance of the preview point in the virtual lane line; l d is the straight-line distance of the preview point; at the same time, calculate the actual steering wheel angle : , where r is the steering wheel transmission ratio;

[0010] S4.2 Feedback control: Calculate the lateral deviation compensation angle and the heading deviation compensation angle to eliminate the lateral deviation and the heading deviation of the vehicle:

[0011] ; ;

[0012] where, KP 1 , KI 1 , KD 1 are the coefficients of the lateral deviation PID controller, KP 2 , KI 2 , KD 2is the coefficient of the heading deviation PID controller, the variable ε is the C0 detected in real time, and the variable β is the C1 detected in real time; S4.3 The actual steering wheel angle and the lateral deviation compensation angle and the heading deviation compensation angle are weighted and fused to generate the total steering wheel angle , and execute.

[0013] Optionally, the generation rule of the virtual lane line in step 3 is: when the left lane line disappears, the left virtual lane line is generated based on the C0 of the original left lane line and the C1 and C2 of the right lane line; when the right lane line disappears, the right virtual lane line is generated based on the C0 of the original right lane line and the C1 and C2 of the left lane line.

[0014] Optionally, the straight-line distance l d of the preview point in step 4.1 is calculated by the following formula: ; where k is the gain coefficient; V is the real-time vehicle speed, in km / h; l b is the basic preview distance, which is 10 m.

[0015] Optionally, the lateral distance e of the preview point is calculated by the following method: Let the coordinates of the preview point in the lane line geometric model be (a, b), substitute the coordinates into the virtual lane line geometric model, and get b = C0 + C1 * a + 1 / 2 * C2 * a 2 , where the ordinate |b| of the preview point in the lane line geometric model is the lateral distance e of the preview point. Combining the coordinate values of the preview point and the geometric relationship formula d of the straight-line distance l of the preview point, calculate the ordinate |b| of the preview point, that is, the lateral distance e of the preview point.

[0016] Optionally, in step 4.3, the total steering wheel angle is calculated according to the following formula: , where A and B are proportionality coefficients, and A + B = 1.

[0017] Optionally, the proportionality coefficient B is positively correlated with the lane line curvature C2.

[0018] According to the second aspect of the present invention, a lane centering driving control system is provided for implementing the above-mentioned lane centering driving control method, which specifically includes the following components:

[0019] Environmental perception module: integrated with a forward camera, used to collect lane line parameters and vehicle speed information, and transmit the lane line parameters and vehicle speed information to the data processing module;

[0020] Data processing module: Equipped with a lane modeling unit, a scene recognition unit, and a virtual lane generation unit, it is used to parse the data information transmitted by the environmental perception module and construct a road model; among which:

[0021] The lane modeling unit is used to construct the geometric model of the lane lines according to the lane line parameters provided by the environmental perception module;

[0022] The scene recognition unit is used to identify the changes in the lane lines on both sides of the vehicle to determine whether it enters the two-in-one / one-in-two scene;

[0023] The virtual lane generation unit is used to construct virtual lane lines in the vehicle coordinate system according to the lane line parameters of the originally disappeared lane line and the lane line on the other side in the two lanes on both sides; at the same time, calculate the maintenance time of the virtual lane lines according to the real-time vehicle speed and identify whether there are new lane lines with effective lengths during the duration of the virtual lane lines;

[0024] Control decision-making module: Built-in with a feedforward-feedback composite controller and a steering wheel angle conversion algorithm, it is used to execute the feedforward-feedback control algorithm during the duration of the virtual lane lines, calculate the actual steering wheel angle, the lateral deviation compensation angle, and the heading deviation compensation angle, and at the same time, according to the steering wheel angle conversion algorithm, weight and fuse the actual steering wheel angle, the lateral deviation compensation angle, and the heading deviation compensation angle to generate the total steering wheel angle and transmit it to the actuator module for execution;

[0025] Actuator module: Includes an electric power steering system EPS, which is responsible for receiving and executing the total steering wheel angle transmitted in the control decision-making module to smoothly drive the vehicle into the new lane.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] The method and system provided by the present invention, based on the one-in-two and two-in-one lane environments, use the original lane lines and adjacent lane lines as references to virtualize the lane lines on the other side, plan a safe driving trajectory, smoothly control the longitudinal and lateral operations of the vehicle, and seamlessly achieve the connection between lane lines. On the one hand, it can avoid frequently asking the driver to take over the vehicle and affecting the driving experience. On the other hand, it can also avoid the vehicle from pressing on or straddling the lane lines, resulting in driving risks. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] By reading the detailed description of the non-limiting embodiments with reference to the following drawings, other features, objectives, and advantages of the present invention will become more obvious:

[0029] Figure 1 It is a schematic diagram of the lane centering driving control method provided in the first embodiment;

[0030] Figure 2Schematic diagram of virtual lane lines in the one - split - into - two scenario for the lane - centering driving control method provided in the first embodiment;

[0031] Figure 3 Schematic diagram of virtual lane lines in the two - split - into - one scenario for the lane - centering driving control method provided in the first embodiment;

[0032] Figure 4 Schematic diagram of the lateral trajectory planning of the vehicle based on preview tracking described in the first embodiment. Detailed implementation manners

[0033] To make the objectives, technical solutions, and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present application. Apparently, the described embodiments are some, but not all, of the embodiments of the present application. Usually, the components of the embodiments of the present application described and illustrated in the accompanying drawings here can be arranged and designed in various different configurations.

[0034] Therefore, the following detailed description of the embodiments of the present application provided in the accompanying drawings is not intended to limit the scope of the present application claimed, but merely represents selected embodiments of the present application. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in the present application without creative efforts fall within the scope of protection of the present application.

[0035] It should be noted that: Similar reference numerals and letters denote similar items in the following drawings. Therefore, once an item is defined in one drawing, it does not need to be further defined and explained in subsequent drawings. In addition, all directional indications (such as up, down, left, right, front, back, bottom, etc.) in the present application are only used to explain the relative positional relationship and movement conditions between components in a specific posture (as shown in the drawings). If the specific posture changes, the directional indications will also change accordingly. Further, the descriptions involving "first", "second", etc. in the application are only for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the quantity of the indicated technical features.

[0036] The first embodiment

[0037] As Figure 1 shown, a lane - centering driving control method is provided in this embodiment, which is applied to the merging and splitting scenarios of two - in - one / one - split - into - two lanes, and specifically includes the following steps:

[0038] Step 1. Road environment perception and lane modeling

[0039] Taking the vehicle's center of mass as the origin of the coordinate system, the forward direction of the vehicle as the x-axis, and the lateral direction of the vehicle as the y-axis to establish a vehicle coordinate system. In this coordinate system, the data information of the front lane lines is collected in real time through a forward camera, and at the same time, the following parameters of each lane line are obtained: a) The lateral offset distance C0 of the lane line in the vehicle coordinate system; b) The angle between the tangent of the lane line and the forward direction (X-axis) of the vehicle in the vehicle coordinate system, that is, the lane line heading angle C1; c) The lane line curvature C2; d) The longitudinal distance DX_n from the proximal end of the lane line to the origin of the vehicle coordinate system; e) The longitudinal distance DX_f from the distal end of the lane line to the origin of the vehicle coordinate system. At most, the information of the following four lane lines is collected simultaneously: the left-left lane line (LL), the left lane line (L), the right lane line (R), and the right-right lane line (RR).

[0040] Based on the above parameters, the following lane line geometric model is established in the vehicle coordinate system: ; where the variable x represents the distance along the forward direction of the vehicle (unit: meter); y represents the distance in the lateral direction of the vehicle (unit: meter), representing the lateral offset of the lane line relative to the vehicle's center of mass. The above model is used to describe the shape of the lane line in real time as the vehicle moves. The origin of the coordinate system is the vehicle's center of mass. When the vehicle moves, the origin of the coordinate system (the vehicle's center of mass) will change continuously. Therefore, each time the camera collects data, the lane line parameters C0, C1, and C2 sensed by the camera each time will change in real time with the movement of the vehicle. For example, when the vehicle is going straight, if the lane line is straight, C1 and C2 may remain relatively stable, while C0 (lateral offset) may change with the position of the vehicle relative to the lane line. If the vehicle is turning, C1 and C2 will also reflect the curvature change of the lane line. In addition, if the vehicle deviates from the center of the lane, C0 will increase or decrease, depending on the deviation direction.

[0041] Step 2. Recognition of merging and splitting scenarios

[0042] As Figure 2 、 Figure 3 shown, in the scenarios of one split into two and two merging into one, one side of the original lane line will disappear, and significant changes will occur in C1 and C2 of one side of the original lane line. When the change amount of the lane line heading angle |ΔC1| or the change amount of the lane line curvature |ΔC2| exceeds a predetermined threshold, it is determined that the vehicle enters the one split into two / two merging into one scenario. Among them, ΔC1 and ΔC2 refer to the real-time change amounts of the heading angle and curvature of the lane line in two adjacent frames. For example, in the one split into two scenario shown in Figure 2 , the first lane line 1 disappears, and significant changes occur in C1 and C2 of the second lane line 2; in the two merging into one scenario shown in Figure 3 , the fourth lane line 4 disappears, and significant changes occur in C1 and C2 of the sixth lane line 6. The specific steps include:

[0043] Calculate the change in the lane line heading angle ΔC1 and the change in the lane line curvature ΔC2 on both sides of the vehicle in real time as the vehicle moves. When it is recognized that one side of the lane line disappears and there is a sudden change in the lane line heading angle or lane curvature on the other side (|ΔC1| is greater than 0.08 rad or |ΔC2| is greater than 0.01), it is determined that the vehicle has entered a one-lane-to-two-lanes / two-lanes-to-one-lane scenario.

[0044] Step 3. Generate a virtual lane line

[0045] As Figure 2 、 Figure 3 shown, after it is determined that the vehicle has entered a one-lane-to-two-lanes or two-lanes-to-one-lane scenario, one of the original lane lines disappears, and a virtual lane line (the dashed line part in Figure 2 Figure 3 ) is constructed on the side where the lane line disappears. At the same time, set the duration of the virtual lane line and identify the new lane line. Specifically, it includes:

[0046] 1. According to the above lane line geometric model , generate a virtual lane line in the vehicle coordinate system. This virtual lane line maintains the lateral reference of the original disappearing lane line, that is, it inherits the C0 of the original disappearing lane line to ensure lateral continuity; at the same time, dynamically adopt the C1 and C2 of the non-disappearing adjacent lane lines as the included angle and curvature of the virtual lane line. For example, in Figure 2 , when the vehicle enters the lane splitting scenario of one-lane-to-two-lanes, the first lane line 1 disappears and the second lane line 2 mutates, generating a left virtual lane line. The left virtual lane line maintains the C0 of the original left first lane line 1 and adopts the C1 and C2 of the second lane line 2. In Figure 3 , when the vehicle enters the two-lanes-to-one-lane scenario, the fourth lane line 4 disappears and the sixth lane line 6 mutates, generating a right virtual lane line. The right virtual lane line maintains the C0 of the original fourth lane line 4 and adopts the C1 and C2 of the sixth lane line 6. The generated virtual lane line satisfies the following geometric model in the vehicle coordinate system: , where the C0 in the geometric model of the virtual lane line adopts the C0 value of the original disappearing lane line, and the C1 and C2 dynamically adopt the C1 and C2 values of the non-disappearing adjacent lane lines.

[0047] 2. Based on the vehicle speed of the host vehicle, set the duration of the virtual lane line by interpolation so that the camera can identify the new lane line. In this embodiment, the duration Ti of the virtual lane is determined according to the real-time vehicle speed V, and the duration is calculated according to the following formula: Ti = 2.5 - V / 120. As shown in Table 1, for safety reasons, the duration Ti of the virtual lane line is 1.5 seconds to 2.5 seconds.

[0048] Table 1

[0049] Vehicle speed V (km / h) 0 120 Duration Ti (seconds) 2.5 1.5

[0050] 3. Identify the effective length of the new lane line:

[0051] During the time of the virtual lane line, a new lane line with an effective length must be identified ( Figure 2 the third lane line 3 in Figure 3 or the fifth lane line 5 in

[0052] Table 2

[0053] Time (seconds) 2.5 1.5 Minimum value of the effective length of the new lane (meters) 20 60

[0054] In order to more smoothly and continuously control the vehicle to enter the new lane, when a new lane line with an effective length is identified during the duration Ti of the virtual lane line, execute the lateral control decision in step 4. If no new lane line is identified or the effective length of the new lane line is insufficient during the duration, the lane keeping assist function exits and the driver is prompted to take over.

[0055] Step 4. Execution of the feedforward-feedback composite control algorithm

[0056] Based on the fitted virtual lane line and the real lane, execute the lateral control decision, and the lateral control decision adopts a feedforward + feedback control algorithm to achieve the lateral control of the vehicle and keep the vehicle smoothly and safely enter the new lane. Specifically, it includes:

[0057] S4.1 Adopt feedforward control to perform the lateral trajectory planning of the vehicle based on preview tracking as shown in Figure 4 specifically including:

[0058] 1. Set the coordinates of the preview point P on the virtual lane line as P(X r , Y r ), where X r represents the longitudinal distance of the preview point, and Y r represents the lateral distance e of the preview point. The abscissa and ordinate of this preview point satisfy the following lane line geometric equation: Y r =C0 + C1*X r +1 / 2*C2*X r 2 ; The straight-line distance between the preview point and the origin of the vehicle coordinate system is ld , l d is calculated by the following formula: ; where k is the gain coefficient (0.2); V is the real-time vehicle speed (unit: km / h); l b is the basic preview distance (10 m); meanwhile, according to Figure 4 the geometric relationship in, it can be known that , combined with the virtual lane line equation Y r = C0 + C1*X r + 1 / 2*C2*X r 2 , the Y r value is calculated, that is, the lateral distance e of the preview point.

[0059] 2. Calculate the front wheel steering angle according to the following formula : ; where L is the wheelbase of the vehicle (unit: m); e is the lateral distance of the preview point; l d is the straight-line distance of the preview point.

[0060] The derivation process of the above formula for the front wheel steering angle is as follows:

[0061] Based on geometric principles, the turning radius can be calculated according to the relationship between the preview point and the vehicle position, and then the front wheel steering angle is obtained through the wheelbase L of the vehicle and the turning radius .

[0062] First, it can be deduced by the sine theorem that , where l d is the straight-line distance of the preview point; is the angle between the preview point and the vehicle's forward direction; is the turning radius.

[0063] Furthermore, it is deduced that: ,

[0064] At the same time, as shown by Figure 4 , it can be obtained that , , L is the wheelbase of the vehicle; e is the lateral distance of the preview point.

[0065] Finally, the formula for calculating the front wheel steering angle is sorted out: .

[0066] 3. Perform the steering wheel angle conversion according to the following formula to convert the theoretical front wheel steering angle to the actual steering wheel angle : , where r is the steering wheel transmission ratio (fixed parameter).

[0067] S4.2 Perform feedback control based on real-time PID correction to eliminate the lateral deviation of the vehicle and the heading deviation , specifically including:

[0068] 1. Real-time monitor the lateral and heading deviation amounts of the current vehicle: Among them, the lateral deviation of the vehicle is C0 detected in real time, and the heading deviation is C1 (the included angle of the lane lines) detected in real time;

[0069] 2. Calculate the lateral deviation compensation rotation angle and the heading deviation compensation rotation angle to eliminate the lateral deviation of the vehicle and the heading deviation :

[0070]

[0071]

[0072] Among them, KP 1 , KI 1 , KD 1 are the coefficients of the lateral deviation PID controller, KP 2 , KI 2 , KD 2 are the coefficients of the heading deviation PID controller. The variable ε is C0 detected in real time, and the variable β is C1 detected in real time.

[0073] S4.3 Weight and fuse the feedforward and feedback amounts to generate the steering wheel rotation angle , and hand it over to the actuator EPS for execution;

[0074] Since the proportions of feedforward and feedback in the system are different, coefficients (A, B) are required for adjustment. Obtain the total steering wheel rotation angle required by the system according to the following formula :

[0075]

[0076] Among them, A and B are proportionality coefficients, and A + B = 1. The proportionality coefficients are related to the curvature (i.e., C2) - the greater the curvature, the greater B, to eliminate the predictable lateral deviation and heading deviation. Vice versa.

[0077] The second embodiment

[0078] This embodiment provides a lane centering driving control system for implementing the lane centering driving control method described in the first embodiment, specifically including the following parts:

[0079] Environmental perception module: Integrates a forward camera for collecting lane line parameters and vehicle speed information; in this module, a two-dimensional coordinate system is established with the vehicle centroid as the origin, and five parameters of the front lane line are collected through the forward camera: a) the lateral offset distance C0 of the lane line in the vehicle coordinate system; b) the angle between the tangent of the lane line and the vehicle's forward direction (X-axis) in the vehicle coordinate system, i.e., the lane line heading angle C1; c) the lane line curvature C2; d) the longitudinal distance DX_n from the proximal end of the lane line to the origin of the vehicle coordinate system; e) the longitudinal distance DX_f from the distal end of the lane line to the origin of the vehicle coordinate system, and the above collected parameters are uploaded to the data processing module.

[0080] Data processing module: Equipped with a lane modeling unit, a scene recognition unit, and a virtual lane generation unit for parsing the data information transmitted by the environmental perception module and constructing a road model; among them:

[0081] The lane modeling unit is used to construct a geometric model of the lane line according to the lane line parameters provided by the environmental perception module: ;

[0082] The scene recognition unit is used to identify the changes in the lane lines on both sides of the vehicle to determine whether it enters the two-in-one / one-in-two scene. The specific recognition content is whether one side of the lane line disappears and the change in the lane line heading angle |ΔC1| or the change in the lane line curvature |ΔC2| on the other side exceeds the preset threshold;

[0083] The virtual lane generation unit is used to construct a virtual lane line in the vehicle coordinate system according to the CO of the originally disappeared lane line in the two side lanes and the C1 and C2 of the lane line on the other side, and the virtual lane line satisfies the geometric model of the lane line: ; At the same time, calculate the maintenance time of the virtual lane line according to the real-time vehicle speed and identify whether there is a new lane line with an effective length during the duration of the virtual lane line.

[0084] Control decision-making module: Built-in a feedforward-feedback composite controller and a steering wheel angle conversion algorithm, used to execute the feedforward-feedback control algorithm during the duration of the virtual lane line, calculate the actual steering wheel angle and the lateral deviation compensation angle and the heading deviation compensation angle , and at the same time, according to the steering wheel angle conversion algorithm, the actual steering wheel angle and the lateral deviation compensation angle and the heading deviation compensation angle are weighted and fused to generate the total steering wheel angle and it is transmitted to the actuator module for execution.

[0085] Actuator module: It includes an Electric Power Steering (EPS) system, which is responsible for receiving and executing the total steering wheel angle transmitted from the control decision-making module , and smoothly driving the vehicle into the new lane.

[0086] The specific embodiments of the present invention have been described above. Through the above description, relevant staff can make various changes and modifications completely within the scope of not deviating from the technical idea of the present invention.

Claims

1. A lane centering driving control method, characterized in that: The following steps are involved: Step S1. A vehicle coordinate system is established with the center of mass of the vehicle as the origin of the coordinate system, the forward direction of the vehicle as the x-axis, and the lateral direction of the vehicle as the y-axis. The vehicle's forward camera collects the lane line information in front in real time, obtains the lateral offset distance C0, lane line heading angle C1, and lane line curvature C2 of each lane line in the vehicle coordinate system, and establishes a geometric model of the lane line in the vehicle coordinate system based on the above parameters: , where variable x represents the distance along the vehicle's forward direction; y represents the distance in the lateral direction of the vehicle, indicating the lateral offset of the lane line relative to the center of mass of the vehicle. The model is used to describe the shape of the lane line in real time as the vehicle moves; Step S2. Calculate the heading angle change ΔC1 and curvature change ΔC2 of the lane lines on both sides of the vehicle in real time. When the lane line on one side disappears and |ΔC1|> 0.08 or |ΔC2|> 0.01 of the lane line on the other side is detected, it is determined that the lane has entered a one-to-two / two-in-one scenario; Step S3. Generate a virtual lane line in the vehicle coordinate system based on the original disappeared lane line C0, the lane lines C1 and C2 on the other side of the vehicle, and the lane line geometry model established in step S1; calculate the duration Ti of the virtual lane line according to the real-time vehicle speed V: Ti=2.5−V / 120, where Ti∈[1.5, 2.5] seconds, V is the real-time vehicle speed, unit: km / h; within the Ti time, if the length L of the new lane line is identified to be ≥20+40*(2.5−Ti) meters, the new lane line is deemed to have a valid length, and step 4 is executed, otherwise the driver is prompted to take over the vehicle; Step S4. During the virtual lane line duration Ti, execute the feedforward-feedback control algorithm, including: S4.1 Feedforward control: calculate the front wheel turning angle δ by the following formula: , where L is the wheelbase of the vehicle; e is the lateral distance of the preview point in the virtual lane line; l d is the straight-line distance of the preview point; at the same time, the actual steering wheel angle is calculated : , where r is the steering wheel gear ratio; S4.2 Feedback control: Calculate the lateral deviation compensation angle using the following formula: and heading deviation compensation angle To eliminate the lateral deviation of the vehicle and heading deviation : ； ； Among them, KP1, KI1, KD1 are the coefficients of the lateral deviation PID controller, KP2, KI2, KD2 are the coefficients of the heading deviation PID controller, the variable ε is the real-time detected C0, and the variable β is the real-time detected C1; S4.3 The actual steering wheel angle Compensation angle with lateral deviation and heading deviation compensation angle Weighted fusion to generate the total steering wheel angle , and execute.

2. The method according to claim 1, characterized in that: The generation rule of the virtual lane line in step 3 is: when the left lane line disappears, the left virtual lane line is generated based on C0 of the original left lane line and C1 and C2 of the right lane line; when the right lane line disappears, the right virtual lane line is generated based on C0 of the original right lane line and C1 and C2 of the left lane line.

3. The method according to claim 1, characterized in that: The straight-line distance l of the preview point in step 4.1 d Calculated by the following formula: ; Where k is the gain coefficient; V is the real-time vehicle speed, in km / h; l b The basic preview distance is 10m.

4. The method according to claim 3, characterized in that The lateral distance e of the preview point is calculated by the following method: Assume that the coordinates of the preview point in the lane line geometry model are (a, b), substitute the coordinates into the virtual lane line geometry model, and obtain b=C0+C1*a+1 / 2*C2*a 2 , where the ordinate of the preview point in the lane geometry model |b| is the lateral distance e of the preview point, combined with the coordinate value of the preview point and the straight-line distance l of the preview point d The geometric relationship formula , calculate the vertical coordinate |b| of the preview point, that is, the horizontal distance e of the preview point.

5. The method according to claim 1, characterized in that In step 4.3, the total steering wheel angle Calculated according to the following formula: , where A and B are proportional coefficients, and A+B=1.

6. The method according to claim 5, characterized in that The proportional coefficient B is positively correlated with the lane line curvature C2.

7. A lane centering driving control system, characterized in that: The method for controlling a vehicle in a lane centering according to any one of claims 1 to 6 specifically comprises the following components: Environmental perception module: integrated with a forward-facing camera, used to collect lane line parameters and vehicle speed information, and transmit the lane line parameters and vehicle speed information to the data processing module; Data processing module: equipped with lane modeling unit, scene recognition unit and virtual lane generation unit, used to analyze the data information transmitted by the environment perception module and build a road model; among which: The lane modeling unit is used to construct a geometric model of the lane line according to the lane line parameters provided by the environment perception module; The scene recognition unit is used to recognize changes in lane lines on both sides of the vehicle to determine whether it enters a two-in-one / one-split-two scene; The virtual lane generation unit is used to construct a virtual lane line in the vehicle coordinate system according to the lane line parameters of the original disappeared lane line and the lane line on the other side in the lanes on both sides; at the same time, the maintenance time of the virtual lane line is calculated according to the real-time vehicle speed, and whether a new lane line with a valid length appears within the duration of the virtual lane line; Control decision module: Built-in feedforward-feedback composite controller and steering wheel angle conversion algorithm, used to execute the feedforward-feedback control algorithm within the duration of the virtual lane line, calculate the actual steering wheel angle, lateral deviation compensation angle and heading deviation compensation angle, and at the same time, according to the steering wheel angle conversion algorithm, weightedly fuse the actual steering wheel angle with the lateral deviation compensation angle and heading deviation compensation angle to generate the total steering wheel angle and pass it to the actuator module for execution; Actuator module: Contains the electric power steering system EPS, which is responsible for receiving and executing the total steering wheel angle transmitted in the control decision module to enable the vehicle to smoothly enter the new lane.

Images