JP2020132009A - Travel control method and travel control device for vehicle - Google Patents

Abstract

To provide a travel control method and a travel control device for a vehicle capable of executing proper control to behavior of an own vehicle when control intervention to the vehicle is performed in an emergency.SOLUTION: A travel control device 100 comprises a track controller 8 for determining a target track Tand a motion controller 9 for controlling behavior of an own vehicle K. The track controller 8 outputs a revolution command so that the own vehicle K follows the target track Tand reaches a target lateral position Yat a forward gazing point Q, and the motion controller 9 estimates an estimation lateral position Ythat the own vehicle K can reach at the forward gazing point Q according to the vehicle characteristics of the own vehicle K identified in advance under the revolution command, and controls the behavior of the own vehicle K on the basis of a lateral deviation between the target lateral position Yand the estimation lateral position Y.SELECTED DRAWING: Figure 4

Description

The present invention relates to a travel control method and a travel control device for controlling the travel of the own vehicle.

The conventional vehicle travel control device calculates an estimated lateral position that the own vehicle is estimated to reach at the forward gazing point based on the current steering angle of the own vehicle. Then, the travel control device calculates the lateral displacement amount and the lateral displacement speed from the target traveling path at the estimated lateral position in order to calculate the steering assist amount and the acceleration / deceleration command value corresponding thereto (Patent Document 1).

International Publication No. 2016/163210

However, in the travel control device shown in Patent Document 1, since the estimated lateral position of the own vehicle is estimated using only the steering angle information at the time of calculation, the estimated lateral position calculated by the travel control device is the vehicle characteristic of the own vehicle. Is not reflected. Therefore, it was not possible to accurately grasp the lateral deviation between the target lateral position according to the target trajectory in the forward gazing point and the estimated lateral position that the own vehicle can reach based on the vehicle characteristics. As a result, when the travel control device performs control intervention on the own vehicle in an emergency such as when the own vehicle goes off the course, there is a possibility that unnecessary control is performed on the behavior of the own vehicle.

The problem to be solved by the present invention is to provide a vehicle travel control method and a travel control device capable of appropriately controlling the behavior of the own vehicle when performing control intervention on the own vehicle in an emergency. ..

The vehicle travel control method and the travel control device according to the present invention use the motion controller to estimate the estimated lateral position that the own vehicle can reach from the forward gazing point in response to the turning command from the track controller, and target the target. The above problem is solved by controlling the traveling of the own vehicle based on the lateral deviation between the lateral position and the estimated lateral position.

According to the vehicle travel control method and the travel control device according to the present invention, when a control intervention is performed on the own vehicle in an emergency, it is possible to appropriately control the behavior of the own vehicle.

It is a block diagram which shows the structure of the vehicle travel control system including the vehicle travel control device which concerns on 1st Embodiment of this invention. It is a flowchart which shows the outline of the travel control of own vehicle by the travel control device shown in FIG. It is a flowchart which shows the outline of the behavior control of own vehicle by the traveling control device shown in FIG. It is a flowchart which shows the method of calculating the lateral deviation between the target lateral position and the estimated lateral position in the forward gazing point by the traveling control device shown in FIG. FIG. 5 is a plan view showing an example of a traveling track of the own vehicle when a turning command is output by the trajectory controller of the traveling control device shown in FIG. 1.

Hereinafter, the traveling control device 100 according to the embodiment of the present invention will be described with reference to FIGS. 1 to 5.
FIG. 1 is a block diagram showing a configuration of a travel control system 101 including a travel control device 100. The vehicle travel control method and the vehicle travel control device 100 according to the present invention autonomously control the behavior of the drive system actuator 11, the braking system actuator 12, and the steering system actuator 13 for traveling the own vehicle K by a computer. It is a travel control method and a travel control device.

The travel control device 100 is composed of one or more computers and software installed on the computers. The travel control device 100 includes a track controller 8 that determines a target trajectory of the own vehicle K from the current location to the destination, and a drive system actuator 11 and a braking system actuator 12 of the own vehicle K based on a command from the track controller 8. And a motion controller 9 for controlling the steering system actuator 13. That is, the travel control device 100 includes a ROM that stores a program for exerting each function of the track controller 8 and the motion controller 9, a CPU that executes the program stored in the ROM, and an accessible storage device. It consists of a RAM that functions as. As the operating circuit, MPU, DSP, ASIC, FPGA or the like can be used instead of or in combination with the CPU.

The track controller 8 is a vehicle K from the current location to the destination based on information from the navigation device 1, the map database 2, the vehicle position detector 3, the camera 4, the radar device 5, the vehicle speed sensor 6, and the input unit 7. The target trajectory of is calculated and determined. The target track determined by the track controller 8 is output as data including one or more lanes, a straight line, a course including a curve having a curvature or a traveling direction, or a combination thereof. Further, the trajectory controller 8 calculates and outputs the required vertical force FxAD and the required lateral force FyAD at the current location at predetermined time intervals. On the other hand, the motion controller 9 controls the behavior of the drive system actuator 11, the braking system actuator 12, and the steering system actuator 13 of the own vehicle K based on the track information determined by the track controller 8.

The navigation device 1 selects from a display capable of displaying information on the current position of the own vehicle K and information such as a travel route to the destination, and the input destination and the current location detected by the own vehicle position detector 3. It includes a computer equipped with a program that calculates a traveling route according to the route calculation mode.

The map database 2 stores three-dimensional high-definition map information based on the road shape detected when traveling on an actual road using a data acquisition vehicle. The three-dimensional high-definition map information stored in this map database 2 includes map information, boundary information at each map coordinate, two-dimensional position information, three-dimensional position information, road information, road attribute information, ascending information, descending information, and the like. Lane identification information, connection destination lane information, etc. are included. Road information and road attributes include road width, radius of curvature, shoulder structure, road traffic regulations (speed limit, lane changeability), road confluences, branch points, toll gates, lane reduction positions, service areas. / Contains information such as parking areas.

The own vehicle position detector 3 is composed of a GPS unit, a gyro sensor, a vehicle speed sensor, and the like. The own vehicle position detector 3 detects radio waves transmitted from a plurality of satellite communications by the GPS unit, periodically acquires the position information of the own vehicle K, and the acquired position information of the own vehicle K and a gyro sensor. Based on the angle change information acquired from the vehicle speed sensor and the vehicle speed acquired from the vehicle speed sensor, the current position information of the own vehicle K is periodically detected.

The camera 4 is composed of an image sensor such as a CCD wide-angle camera, and is provided on the own vehicle K in front and behind and on both sides as needed, and images the surroundings of the own vehicle K to acquire image information. The camera 4 may be a stereo camera or an omnidirectional camera, and may include a plurality of image sensors. From the acquired image data, the camera 4 detects the road and structures around the road in front of the own vehicle K, road markings, signs, other vehicles, two-wheeled vehicles, bicycles, pedestrians, etc. as the surrounding conditions of the own vehicle K. To do.

The radar device 5 is provided on the front, rear, and both sides of the own vehicle K, irradiates the periphery of the own vehicle K with millimeter waves or ultrasonic waves, scans a predetermined range around the own vehicle K, and scans the predetermined range around the own vehicle K. Detects obstacles such as other vehicles, motorcycles, bicycles, pedestrians, curbs on the shoulder, guardrails, walls, and fillings that exist in the surrounding area. For example, the radar device 5 detects the relative position (azimuth) between the obstacle and the own vehicle K, the relative speed of the obstacle, the distance from the own vehicle K to the obstacle, and the like as the surrounding conditions of the own vehicle K.

The vehicle speed sensor 6 measures the rotational speed of the drive shaft or the like, and detects the traveling speed of the own vehicle K based on this. The input unit 7 is composed of a mechanical switch, an electronic switch displayed on the display, and the like, and the driver inputs information such as a destination and a decision as to whether or not to perform automatic operation.

Next, an outline of the overall control by the travel control device 100 will be described with reference to FIG.
First, the travel control device 100 estimates its own position based on the position information of its own vehicle K obtained by the own vehicle position detector 3 and the map information of the map database 2 (step S1). Further, the travel control device 100 recognizes pedestrians and other obstacles around the own vehicle K by the camera 4 and the radar device 5 (step S2). Then, the self-position information estimated in step S1 and the information such as obstacles recognized in step S2 are expanded and displayed on the map of the map database 2 (step S3).

Further, when the destination is input from the input unit 7 and the start instruction of the autonomous driving control is input, the destination is set on the map of the map database 2 (step S4), and the navigation device 1 and the map database 2 are used. Then, route planning from the current location to the destination is performed (step S5). Then, the action of the own vehicle K is determined based on the information developed on the map (step S6). Specifically, for example, at each position of a plurality of intersections existing on the planned route, the direction in which the own vehicle K turns is determined. Next, drive zone planning is performed on the map of the map database 2 based on information such as obstacles recognized by the camera 4 or the radar device 5 (step S7). Specifically, in consideration of the relationship with obstacles, which lane the own vehicle K should travel in at a predetermined position or a predetermined interval on the route is appropriately set. Then, the track controller 8 sets the target trajectory of the own vehicle K based on the input position information of the current location and the destination, the set route information, the behavior of the own vehicle K, and the information of the drive zone (step). S8). Further, the motion controller 9 controls the behavior of the own vehicle K so that the own vehicle K follows the target trajectory (step S9).

Next, the outline of the behavior control of the own vehicle K by the motion controller 9 will be described with reference to FIG.
The control mode of the travel control device 100 of the present embodiment is an autonomous driving mode in which the driver executes autonomous driving control of the own vehicle K, and a manual mode in which the own vehicle K is driven by the driver's driving operation without executing the autonomous driving control. The driving mode can be selected. For example, when the driver selects the autonomous driving mode of the input unit 7, the execution of the autonomous driving control is started, and when the driver selects the end of the autonomous driving mode of the input unit 7, the autonomous driving control is terminated and the manual driving mode is started. Transition to. Further, when an operation intervention by the driver such as a steering wheel operation, a brake operation or an accelerator operation is performed during the execution of the autonomous driving control, the manual operation takes precedence over the autonomous driving control.

A command value based on the required longitudinal force FxAD and the required lateral force FyAD generated by the trajectory controller 8 of the automatic driving hierarchy according to the target trajectory is input to the motion controller 9 (step S11). Further, a command value based on the manual operation of the driver is input to the motion controller 9 in parallel (step S12). The motion controller 9 adjusts the command value in the autonomous driving mode and the command value based on the manual operation (step S13), and outputs the longitudinal force command value Fx and the lateral force command value Fy (step S14). For example, in the adjustment in step S13, the content that the manual operation is prioritized over the autonomous driving control is defined. Then, based on the longitudinal force command value Fx and the lateral force command value Fy, the behavior of the vehicle body is controlled so that the own vehicle K follows the target trajectory (step S15), and the behavior of the wheels is controlled. (Step S16). As a result, the drive system actuator 11, the braking system actuator 12, and the steering system actuator 13 of the own vehicle K are operated by these controls (step S17).

The vehicle body behavior control in step S15 and the wheel behavior control in step S16 are controlled based on the vertical force command value Fx and the lateral force command value Fy output by the motion controller 9 in step S14. In the autonomous driving mode, the required vertical force FxAD and the required lateral force FyAD output by the track controller 8 are most reflected in the control range in which the behavioral stability of the vehicle body and the behavioral stability of the wheels can be optimized. , Vertical force command value Fx and lateral force command value Fy are selected. That is, the track controller 8 generates a target track based on the current location, the destination, map data, etc., without considering the stability of the vehicle body and the stability of the wheels of the own vehicle K, and determines the behavior of the own vehicle K. Control. On the other hand, the motion controller 9 limits the traveling control of the own vehicle K within a range in which the stability of the vehicle body and the stability of the wheels are taken into consideration with respect to the target trajectory. Therefore, the target trajectory calculated by the track controller 8 may not match the actual traveling track of the own vehicle K controlled by the motion controller 9.

The target trajectory information generated by the travel control device 100 is divided into a required longitudinal force FxAD parallel to the traveling direction of the own vehicle K and a required lateral force FyAD perpendicular to the traveling direction of the own vehicle K. Powered and output. Then, the acceleration / deceleration required for the own vehicle K to follow the target trajectory is controlled from the output of the required longitudinal force FxAD, and the own vehicle K turns along the target trajectory by the output of the required lateral force FyAD. Be controlled.

Next, the procedure for calculating the lateral deviation between the target lateral position Y _RQ and the estimated lateral position Y _POT of the own vehicle K at the forward gazing point Q will be described with reference to FIGS. 4 and 5. In the following description, the current straight direction of the own vehicle K is defined as the vertical direction x, and the direction perpendicular to the vertical direction x is defined as the horizontal direction y. Further, the coordinate position in the vertical direction x is the vertical position, and the coordinate position in the horizontal direction y is the horizontal position. Further, the forward gazing point Q is, for example, a point at a predetermined distance in front of the own vehicle on the vehicle body center line extending in the vertical direction x through the center of the vehicle width of the own vehicle K. This specified distance is obtained by experiments and the like, and is determined by the vehicle speed of the own vehicle K.

First, as shown in FIG. 4, the inertial sensor provided in the own vehicle K measures the yaw rate r [rad / s] indicating the current turning state of the own vehicle K (step S21). Thereby, the current curvature change rate ρ ₀ [rad / m] can be calculated from the following equation (1) based on the yaw rate r and the vehicle speed V [m / s] (step S22). The increase / decrease in the rate of change in curvature corresponds to the increase / decrease in the lateral acceleration of the own vehicle K.

Further, the motion controller 9 calculates the yaw angular acceleration Sr _MODEL [rad / s ² ] based on the vehicle characteristics of the own vehicle K identified in advance (step S23). Based on this yaw angular acceleration Sr _MODEL , the rate of change Sρ ₀ [rad / m ² ] of the rate of change in curvature that can be generated by the own vehicle K is calculated from the following equation (2) (step S24). The rate of change in the rate of change in curvature is the amount of change in the rate of change in curvature with respect to 1 m of movement of the own vehicle K in the vertical direction x.

Further, the motion controller 9 calculates the maximum turning curvature R _MAX [rad], which is the upper limit of the turning curvature that the own vehicle K can achieve, based on the vehicle characteristics of the own vehicle K identified in advance (step S25). ..

The motion controller 9 has the following equation (based on the current curvature change rate ρ ₀ , the change rate Sρ ₀ of the curvature change rate that the own vehicle K can generate, and the maximum turning curvature R _MAX that the own vehicle K can achieve. The vertical position Xs [m] of the lateral acceleration saturation point P that satisfies 3) is calculated (step S26). Therefore, as shown in FIG. 5, when the own vehicle K reaches the lateral acceleration saturation point P, the turning curvature of the own vehicle K becomes equal to the maximum turning curvature R _MAX . Here, the rate of change in curvature of the own vehicle K becomes 0 [rad / m] after the own vehicle K passes the lateral acceleration saturation point P, and the own vehicle K holds the maximum turning curvature R _MAX . It runs in a steady turn. That is, at the lateral acceleration saturation point P, the lateral acceleration of the own vehicle K is saturated.

Comparing the vertical position Xt of the forward gazing point Q and the vertical position Xs of the lateral acceleration saturation point P, the vertical position Xt exists at the same position as the vertical position Xs or at a position close to the current position of the own vehicle K. In this case, the estimated lateral position Y _POT [m] is calculated by the following equation (4) (step S27). That is, in this case, the lateral acceleration of the own vehicle K is not saturated until the front gazing point Q is reached, and the value of the turning curvature continues to increase additionally.

Further, as in the example shown in FIG. 5, when the vertical position Xs of the lateral acceleration saturation point P exists on the front side of the vertical position Xt of the forward gazing point Q, the estimated horizontal position Y _POT is calculated by the following equation (5). Is calculated (step S27). This is because it is estimated that after the own vehicle K has passed the lateral acceleration saturation point P, it makes a steady turn with a constant maximum turning curvature R _MAX until the front gazing point Q is reached.

The minimum lateral position Y _CUR [m] shown in FIG. 5 is the lateral position at the forward gazing point Q when it is assumed that the own vehicle K travels from the current position while maintaining the current curvature change rate ρ _0. The position. The minimum lateral position Y _CUR is _calculated by the following equation (6). Therefore, the estimated lateral position Y _POT that the own vehicle K can reach at the forward gazing point Q takes a larger distance than the minimum lateral position Y _CUR calculated only from the current vehicle speed V and the yaw rate r.

Further, the track controller 8 outputs a turning command to the motion controller 9 so that the own vehicle K follows the target track T _RQ . As shown in FIG. 5, when it is assumed that the own vehicle K follows the target trajectory T _RQ based on the turning command output by the track controller 8, the own vehicle K reaches the forward gazing point Q. _Let the horizontal position of be the target horizontal position Y _RQ . Motion controller 9, the command value based on the requested vertical force FxAD and required lateral force FyAD trajectory controller 8 outputs, calculates the target lateral position _{Y REQ} (Step S28). Then, the motion controller 9 calculates the lateral deviation (Y _RQ −Y _POT ) between the target lateral position Y _RQ and the estimated lateral position Y _POT at the forward gazing point Q (step S29). The estimated lateral position Y _POT is a lateral position that the own vehicle K can actually reach at the forward gazing point Q according to the vehicle characteristics in response to the turning command from the track controller 8. Therefore, if the lateral deviation between the target lateral position Y _RQ and the estimated lateral position Y _POT is equal to or greater than a predetermined value, it is determined that the own vehicle K may go off course. Therefore, the motion controller 9 controls the braking system actuator 12 so that the own vehicle K applies the emergency brake when the lateral deviation between the target lateral position Y _RQ and the estimated lateral position Y _POT is equal to or more than a predetermined value. .. Further, the motion controller 9 controls not only the braking system actuator 12, but also the drive system actuator 11 and the steering system actuator 13 as appropriate according to the lateral deviation between the target lateral position Y _RQ and the estimated lateral position Y _POT. It shall be.

From the above, the travel control device 100 of this embodiment uses the motion controller 9 and responds to the turning command from the track controller 8 according to the vehicle characteristics of the own vehicle K identified in advance. Estimates the estimated lateral position Y _POT that can be reached at the forward gazing point Q. As a result, the motion controller 9 controls the drive system actuator 11, the braking system actuator 12, and the steering system actuator 13 of the own vehicle K based on the lateral deviation between the target lateral position Y _RQ and the estimated lateral position Y _POT. Can be done. Therefore, it is possible to suppress the deviation of the own vehicle K from the target lateral position Y _RQ in the forward gazing point Q, and thus it is possible to suppress the execution of control that does not match the road condition. Further, in the present invention, since the followability to the generated target trajectory T _RQ can be improved, it is possible to suppress an unintended posture without following the target trajectory. For example, in an emergency such as when the own vehicle K goes off course, the travel control device 100 can appropriately control the behavior of the own vehicle K.

In the present invention, in order to consider the control delay time, the preview time or the preview position (forward gazing point Q) from the own vehicle K is set, and the own vehicle K travels according to the target value in the preview time. Used in the system that controls. In the present invention, the turning control can be executed based on the actually reachable lateral position in the preview position. Therefore, it is possible to suppress the attempt to follow the target trajectory T _RQ without considering the control delay time. A conventional method can be applied to the method of setting the preview time, the preview position, and the forward gazing point Q described above.

Further, the motion controller 9 calculates the curvature change rate ρ ₀ of the turning curvature of the own vehicle K according to the yaw rate r indicating the current turning state of the own vehicle K, and the vehicle characteristics of the own vehicle K identified in advance. The rate of change Sρ _{0 of the} rate of change in the curvature of the own vehicle K is calculated accordingly. The motion controller 9 estimates the estimated lateral position Y _POT based on at least the curvature change rate ρ ₀ and the curvature change rate change rate Sρ ₀ . As a result, the estimation accuracy of the estimated horizontal position Y _POT is improved, and the finally feasible estimated horizontal position Y _POT can be calculated.
Further, by calculating the change rate Sρ ₀ of the curvature change rate of the own vehicle K according to the vehicle characteristics of the own vehicle K, it is possible to prevent the curvature change rate of the own vehicle K from being excessively calculated. ..

Further, the motion controller 9 calculates the maximum turning curvature R _MAX , which is the upper limit of the turning curvature of the own vehicle K, according to the vehicle characteristics of the own vehicle K identified in advance, and has a curvature change rate ρ ₀ and a curvature change. Based on the rate of change Sρ ₀ and the maximum turning curvature R _MAX , the vertical position Xs of the lateral acceleration saturation point P at which the lateral acceleration of the own vehicle K is saturated is calculated. Here, since it is presumed that the behavior of the own vehicle K becomes unstable at the lateral acceleration saturation point P, the lateral position of the own vehicle K estimated at the lateral acceleration saturation point P and the side of the actual own vehicle K There is a possibility that the position will deviate. Therefore, by using the vertical position Xs for estimating the position of the lateral acceleration saturation point P, the estimation accuracy of the estimated horizontal position Y _POT is further improved.

When the vertical position Xs of the lateral acceleration saturation point P is closer to the current position of the own vehicle K than the vertical position Xt of the forward gaze point Q, the own vehicle K moves from the lateral acceleration saturation point P to the forward gaze point Q. Until then, the motion controller 9 estimates the estimated lateral position Y _POT , assuming that steady turning is performed while maintaining the maximum turning curvature R _MAX . Therefore, by considering both the turning state until the own vehicle K reaches the lateral acceleration saturation point P and the turning state after the own vehicle K has passed the lateral acceleration saturation point P, the estimated lateral position Y _POT The estimation accuracy is improved.

Further, when the lateral deviation between the target lateral position Y _RQ and the estimated lateral position Y _POT is equal to or greater than a predetermined value, the motion controller controls the braking system actuator 12 of the own vehicle K so that the own vehicle K applies the emergency brake. To do. As a result, it is possible to prevent the own vehicle K from going off course in an emergency.

100 ... Travel control device 8 ... Trajectory controller 9 ... Motion controller 11 ... Drive system actuator 12 ... Braking system actuator 13 ... Steering system actuator K ... Own vehicle P ... Lateral acceleration saturation point Q ... Forward gazing point R _MAX ... Maximum turning curvature T _{REQ ...} target trajectory Xs ... vertical position Y _{POT ...} the rate of change of the estimated lateral position Y _{REQ ...} target lateral position [rho _{0 ...} curvature change rate Sρ _{0 ...} curvature rate of change of the vertical position Xt ... forward fixed point of the lateral acceleration saturation point

Claims (6)

A travel control device including a track controller that determines a target trajectory of the own vehicle from the current location to the destination, and a motion controller that controls an actuator for traveling the own vehicle based on a command from the track controller. In the vehicle travel control method for controlling the travel of the own vehicle using
Using the track controller, the own vehicle follows the target track and outputs a turning command so that the vehicle reaches the target lateral position at the forward gazing point.
Using the motion controller,
In response to the turning command from the track controller, the estimated lateral position that the own vehicle can reach at the forward gazing point is estimated according to the vehicle characteristics of the own vehicle identified in advance.
A vehicle travel control method for controlling the actuator for traveling the own vehicle based on the lateral deviation between the target lateral position and the estimated lateral position. Using the motion controller,
The curvature change rate of the turning curvature of the own vehicle is calculated according to the current turning state of the own vehicle.
The rate of change of the curvature change rate of the own vehicle is calculated according to the vehicle characteristics of the own vehicle identified in advance.
The vehicle traveling control method according to claim 1, wherein the estimated lateral position is estimated based on at least the rate of change in curvature and the rate of change in the rate of change in curvature. Using the motion controller,
The maximum turning curvature, which is the upper limit of the turning curvature of the own vehicle, is calculated according to the vehicle characteristics of the own vehicle identified in advance.
The second aspect of the present invention, wherein the vertical position of the lateral acceleration saturation point at which the lateral acceleration of the own vehicle is saturated is calculated based on the curvature change rate, the change rate of the curvature change rate, and the maximum turning curvature. Vehicle travel control method. When the vertical position of the lateral acceleration saturation point is closer to the current position of the own vehicle than the vertical position of the forward gazing point.
Claim that the estimated lateral position is estimated assuming that the own vehicle makes a steady turn while maintaining the maximum turning curvature while the own vehicle reaches the forward gazing point from the lateral acceleration saturation point. The vehicle traveling control method according to 3. Any of claims 1 to 4, wherein when the lateral deviation between the target lateral position and the estimated lateral position is equal to or greater than a predetermined value, the motion controller controls the actuator so that the own vehicle applies an emergency brake. The vehicle running control method according to item 1. A track controller that determines the target track of the vehicle from the current location to the destination,
It is provided with a motion controller that controls an actuator for traveling the own vehicle based on a command from the track controller.
The track controller outputs a turning command so that the own vehicle follows the target track and reaches the target lateral position at the forward gazing point.
The motion controller
In response to the turning command from the track controller, the estimated lateral position that the own vehicle can reach at the forward gazing point is estimated.
A vehicle travel control device that controls the actuator for traveling the own vehicle based on the lateral deviation between the target lateral position and the estimated lateral position.

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