Lateral control strategy for low-speed following stop and start

Abstract

The invention discloses a transverse control strategy for low-speed following parking and starting, which comprises the following steps of: identifying following parking and starting of a vehicle by combined longitudinal control of the state of an ACC and the given vehicle state of the ACC during longitudinal control of the vehicle, then optimizing a transverse LCK control function, and comprehensively considering the stability of transverse control when the vehicle is at a low speed. According to the invention, transverse control is carried out on the vehicle comprehensively according to the motion parameters of the front vehicle, an ideal effect is achieved, intelligence of the vehicle is increased, and operation is more convenient when the vehicle follows the vehicle on an urban road and passes through a traffic light intersection.

Description

Technical Field

[0001] The invention belongs to the field of vehicle control, and in particular relates to a lateral control strategy for low-speed following, stopping and starting. Background Art

[0002] With the development of automobile technology, assisted driving functions are becoming more and more popular. Vehicle lateral control is very important. It can stabilize the lateral driving of the vehicle and reduce the burden on the driver. Lane Centering Control (LCK) is a common function. The main state and jump logic of the current mass-produced LCK algorithm are fixed. Adaptive cruise control (ACC) must be activated before LCK is activated. ACC controls the longitudinal speed of the vehicle and has multiple states.

[0003] The main states of ACC control are introduced as follows: Override means that when the ACC function is turned on, the driver operates the accelerator pedal, and the depth of the accelerator pedal exceeds the accelerator pedal depth value requested by ACC, and the vehicle responds to the driver's accelerator pedal operation; ON state means that when there is a target vehicle in front of the vehicle and the speed set by the driver is greater than the target speed in front, ACC controls the vehicle to travel at the speed in front; SpeedControl state means that when there is no target vehicle in front, or there is a target vehicle in front but the speed of the target vehicle in front is greater than the cruising speed set by the driver, ACC controls the vehicle to travel at the set cruising speed; tempStop state means that ACC controls the vehicle to follow the target in front to a stop state, and when the vehicle in front starts again, ACC controls the vehicle to start again and follow the vehicle. The duration of tempStop is generally about 3s. If this time is exceeded, ACC will enter the Stop state; Stop state means that ACC controls the vehicle to stop following the vehicle in front. After the vehicle leaves, the driver can step on the accelerator or operate the ACC system switch, and the ACC system controls the vehicle to follow the vehicle in front again.

[0004] There are two existing strategies for LCK lateral control when the vehicle is following, stopping or starting: Option 1 is that LCK retreats when ACC stops, and LCK is not automatically activated after ACC is restarted. The operation is simple, but the driver needs to restart LCK when he stops and starts again at a red light or in congestion, which is distracting and reduces convenience; Option 2 is that LCK does not retreat when ACC stops, and no control value is output when the vehicle is stationary. LCK resumes control when ACC restarts. In this solution, there is a risk of activating LCK when the vehicle is stationary, and the speed detection error may cause the vehicle to turn on the spot and damage the steering system. When ACC changes from Stop to Override, LCK resuming control will interfere with the driver. Therefore, a lateral control strategy for low-speed following, stopping and starting is needed to solve the above problems. Summary of the invention

[0005] In order to solve the problems raised in the above background technology, the present invention provides a lateral control strategy for low-speed following, stopping and starting.

[0006] To achieve the above object, the present invention provides the following technical solution: a lateral control strategy for low-speed follow-stop and start, comprising the following steps:

[0007] Step 1: Obtain the target information output by the front-end perception device and the vehicle information input by the vehicle;

[0008] Step 2: Based on the information in step 1, the driver activates the ACC function and then operates the LCK switch. After the LCK determines that the lateral system meets the lateral activation conditions, the system is activated, calculates the torque or angle required for the desired lateral control under the current working conditions, controls the vehicle laterally, and monitors the vehicle speed and ACC status.

[0009] Step 3: Based on the information in step 2, when it is detected that the vehicle speed is less than 0.5 km / h, LCK does not output the requested torque or angle. When it is detected that the ACC state enters the Stop state, the LCK function exits and records the exit, while monitoring the ACC state.

[0010] Step 4: Based on the information in step 3, when it is detected that the ACC state is reactivated and enters the Override state, LCK does not resume activation. When the ACC state enters the On state from Override, LCK determines whether there is a lane line. If there is a lane line, the vehicle's lateral direction is controlled according to the lane line to ensure that the vehicle travels within the lane line.

[0011] Step 5: Based on the information in step 3, when it is detected that the ACC state is reactivated and enters the Override state, LCK does not resume activation. When the ACC state enters the On state from Override, LCK determines whether there is a lane line. If there is no lane line, the motion parameters of the preceding vehicle are used to fit a fifth-order polynomial. The fitted fifth-order polynomial is used to control the lateral direction of the vehicle to ensure that the vehicle follows the motion trajectory of the preceding vehicle.

[0012] Step 6: Based on the information in step 3, when the ACC state is detected to be reactivated and enter the Override state, LCK does not resume activation. When the ACC state enters the SpeedControl state from the Override state, LCK determines whether there is a lane line. If there is a lane line, it controls the lateral direction of the vehicle according to the lane line to ensure that the vehicle drives within the lane line. If LCK determines that there is no lane line, LCK is not activated.

[0013] Step 7: Based on the information in step 3, when the ACC state is detected to be reactivated and enters the ON state, LCK determines whether there is a lane line. If there is a lane line, the vehicle's lateral direction is controlled according to the lane line to ensure that the vehicle travels within the lane line.

[0014] Step 8: Based on the information in step 3, when the ACC state is detected to be reactivated and enters the ON state, LCK determines whether there is a lane line. If there is no lane line, the motion parameters of the preceding vehicle are used to fit a fifth-order polynomial. The fitted fifth-order polynomial is used to control the lateral direction of the vehicle to ensure that the vehicle follows the motion trajectory of the preceding vehicle.

[0015] Step 9: Based on the information in step 3, when the ACC state is detected to be reactivated and the vehicle enters the SpeedControl state, LCK determines whether there is a lane line. If there is a lane line, the vehicle's lateral direction is controlled according to the lane line to ensure that the vehicle travels within the lane line. If there is no lane line, LCK is not activated.

[0016] Step 10: According to the previous information, when the ACC state is detected to be exited, the LCK function will exit and will not be automatically restored. When the driver needs the lateral LCK function, he needs to press the LCK function switch again to activate it.

[0017] Compared with the prior art, the present invention has the following beneficial effects:

[0018] 1. The present invention improves the lateral control performance: improves the smoothness of the lateral control of the intelligent driving vehicle in the following stop and starting stages and the safety in the low-speed stage, and enhances the portability of the lateral control algorithm and the adaptability between different vehicle models.

[0019] 2. Improve driving experience: Improve vehicle comfort and make it easier for drivers to stop and start following the vehicle in front at traffic lights and congested roads. The operation is more convenient and reduces driving stress. The LCK function can be automatically restored after starting, making the assisted driving function more intelligent and increasing driving pleasure.

[0020] 3. Optimize control algorithm: Improve the robustness and real-time performance of the longitudinal control algorithm, which will help increase the public's trust in and acceptance of intelligent driving. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] 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:

[0022] Figure 1 This is the overall flow chart of a lateral control strategy for low-speed stop and start;

[0023] Figure 2 The process of the present invention Figure 2 ;

[0024] Figure 3 The process of the present invention Figure 3 . DETAILED DESCRIPTION

[0025] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. The components of the embodiments of the present invention generally described and shown in the drawings here can be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present invention provided in the drawings is not intended to limit the scope of the claimed invention, but merely represents the selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without making creative work belong to the scope of protection of the present invention.

[0026] First, refer to Figures 1 to 3 A lateral control strategy for low-speed following stop and starting related to an embodiment of the present invention is described in detail.

[0027] Step 1: Obtain the target information ahead output by the camera, millimeter-wave radar and other sensing devices and the vehicle information input by the vehicle;

[0028] Step 2: Based on the information in step 1, the driver activates the ACC function and then operates the LCK switch. After the LCK determines that the lateral system meets the lateral activation conditions, the system is activated, calculates the torque or angle required for the desired lateral control under the current working conditions, controls the vehicle laterally, and monitors the vehicle speed and ACC status.

[0029] Step 3: Based on the information in step 2, when it is detected that the vehicle speed is less than 0.5 km / h, LCK does not output the requested torque or angle. When it is detected that the ACC state enters the Stop state, the LCK function exits and records the exit, while monitoring the ACC state.

[0030] Step 4: Based on the information in step 3, when it is detected that the ACC state is reactivated and enters the Override state, LCK does not resume activation. When the ACC state enters the On state from Override, LCK determines whether there is a lane line. If there is a lane line, the vehicle's lateral direction is controlled according to the lane line to ensure that the vehicle travels within the lane line.

[0031] Step 5: Based on the information in step 3, when it is detected that the ACC state is reactivated and enters the Override state, LCK does not resume activation. When the ACC state enters the On state from Override, LCK determines whether there is a lane line. If there is no lane line, the motion parameters of the preceding vehicle are used to fit a fifth-order polynomial. The fitted fifth-order polynomial is used to control the lateral direction of the vehicle to ensure that the vehicle follows the motion trajectory of the preceding vehicle.

[0032] Step 6: Based on the information in step 3, when the ACC state is detected to be reactivated and enter the Override state, LCK does not resume activation. When the ACC state enters the SpeedControl state from the Override state, LCK determines whether there is a lane line. If there is a lane line, it controls the lateral direction of the vehicle according to the lane line to ensure that the vehicle drives within the lane line. If LCK determines that there is no lane line, LCK is not activated.

[0033] Step 7: Based on the information in step 3, when the ACC state is detected to be reactivated and enters the ON state, LCK determines whether there is a lane line. If there is a lane line, the vehicle's lateral direction is controlled according to the lane line to ensure that the vehicle travels within the lane line.

[0034] Step 8: Based on the information in step 3, when the ACC state is detected to be reactivated and enters the ON state, LCK determines whether there is a lane line. If there is no lane line, the motion parameters of the preceding vehicle are used to fit a fifth-order polynomial. The fitted fifth-order polynomial is used to control the lateral direction of the vehicle to ensure that the vehicle follows the motion trajectory of the preceding vehicle.

[0035] Step 9: Based on the information in step 3, when the ACC state is detected to be reactivated and the vehicle enters the SpeedControl state, LCK determines whether there is a lane line. If there is a lane line, the vehicle's lateral direction is controlled according to the lane line to ensure that the vehicle travels within the lane line. If there is no lane line, LCK is not activated.

[0036] Step 10: According to the previous information, when the ACC state is detected to be exited, the LCK function will exit and will not be automatically restored. When the driver needs the lateral LCK function, he needs to press the LCK function switch again to activate it.

[0037] To achieve the reliability and comfort of the lateral control exit process of the assisted driving system. In the LCK control, the present invention takes into account the scenarios of the vehicle following and starting at low speed, ensuring the intelligence of the LCK control during the low-speed following and stopping of the vehicle and the process from stopping to starting, so that the driver can effectively control the vehicle. At the same time, it can meet the driver's needs when the vehicle needs to follow the vehicle in front and start after passing through traffic lights and congested sections in urban roads. There is no need to frequently activate the lateral control LCK function. LCK optimizes the lateral control of the vehicle according to the vehicle speed and the working status of ACC.

[0038] The activation of the LCK function requires the fulfillment of various conditions, the main ones of which are as follows:

[0039] The vehicle speed meets the LCK activation conditions, and the speed range generally needs to be less than 120km / h, which is mainly to ensure the safety of the vehicle.

[0040] The lane line meets the conditions. The vehicle needs to be in the presence of a lane line, or in the absence of a lane line but with a target vehicle in front. The ACC system controls the vehicle to follow the vehicle in front. The LCK system can simulate the driving trajectory of the vehicle in front based on the target vehicle in front and use it as a lane line for lateral control. The LCK system controls the vehicle to follow the vehicle in front.

[0041] ACC function is activated. ACC is in longitudinal control of the vehicle. Only after ACC function is activated, LCK function is allowed to be activated;

[0042] The vehicle conditions meet the requirements, which mainly include that the steering wheel angle of the vehicle is less than a certain angle, the turn signal is not turned on, the brake pedal is not pressed, and there are no faults in the LCK-related systems. The requirements of each company may vary, but the main purpose is to ensure the safety of lateral control and prevent lateral control from affecting the driver's operation of the vehicle. When the driver has a strong intention to control the vehicle, the LCK function needs to be suppressed.

[0043] In order to improve the safety and comfort of the lateral control function of the auxiliary driving controller during low-speed following and starting, the present invention will comprehensively consider the vehicle speed and the activation state of the ACC system to optimize the control of LCK and consider exiting and automatically resuming at the appropriate time. The specific considerations are as follows:

[0044] Vehicle speed detection: LCK detects vehicle speed. When the vehicle speed exceeds a certain value, generally greater than 120km for a certain period of time, the LCK function will exit. When the vehicle speed is lower than 0.5km / h, LCK keeps the system activated but no longer outputs the requested lateral control torque or steering angle value to prevent the LCK from requesting lateral control when the vehicle is stationary, causing the vehicle to turn when it is stationary; when the vehicle speed is greater than 0.6km / h, LCK is allowed to output the lateral control torque or steering angle value.

[0045] ACC status detection: When the ACC system enters the Stop state from activation, the vehicle stops following the vehicle in front. The ACC system controls the vehicle to keep the brakes stopped, the LCK function exits, and the exit status is recorded. When ACC is reactivated from Stop, LCK performs corresponding operations according to the following two working conditions. When the ACC system enters Stop mode for a period of time (generally 3 minutes to 5 minutes, different companies have different regulations. When this time is exceeded, the ACC system will exit from Stop mode and the ACC system will enter the inactive state), when the vehicle in front of the ACC starts from a standstill, the ACC system can be reactivated from Stop. There are two main ways. One is that the driver presses the accelerator pedal, the ACC system is reactivated, and enters the Override state from Stop. At this time, LCK judges that the driver's intention to operate the vehicle is relatively obvious. LCK does not automatically activate, but waits for the driver to exit the control of the vehicle before automatically reactivating. When the driver does not press the accelerator pedal, the ACC system enters the On state or the SpeedControl state. When LCK detects that ACC has entered the On state, LCK returns to the active state and detects whether there is a lane line. When the lane line exists, LCK controls the vehicle's lateral direction according to the lane line to ensure that the vehicle is driving in the center of the lane; when it is detected that the lane line does not exist, the center line of the lane is fitted according to the motion trajectory of the front vehicle followed by ACC, and the fitted lane line is used to control the vehicle's lateral direction. When LCK detects that ACC has entered the SpeedControl state, it means that the target vehicle in front is lost, or the speed of the front vehicle is greater than the cruising speed set by the driver. At this time, LCK detects whether there is a lane line. When the lane line exists, LCK resumes activation and controls the vehicle's lateral direction to make the vehicle drive in the center of the lane; when it is detected that the lane line does not exist, because there is no target vehicle in front, LCK does not allow automatic recovery. Another way is that the driver operates the ACC start switch or recovery switch to control ACC to activate directly, and the ACC system state directly enters the On state or SpeedControl state from Stop. When LCK determines that the driver has not intervened in the control of the vehicle, LCK does not need to wait in the Override state as in the previous method, but can directly enter the activated state. When LCK detects that ACC has entered the On state, LCK returns to the activated state and detects whether there is a lane line. When the lane line exists, LCK controls the vehicle's lateral direction according to the lane line to ensure that the vehicle travels in the center area of ​​the lane; when it is detected that the lane line does not exist, the center line of the lane is fitted according to the motion trajectory of the front vehicle followed by ACC, and the fitted lane line is used to control the vehicle's lateral direction.When LCK detects that ACC has entered the SpeedControl state, it means that the target vehicle in front has been lost, or the speed of the vehicle in front is greater than the cruising speed set by the driver. At this time, LCK detects whether there is a lane line. When the lane line exists, LCK resumes activation and controls the vehicle's lateral direction to keep the vehicle driving in the center of the lane. When it is detected that the lane line does not exist, because there is no target vehicle in front, LCK is not allowed to automatically recover.

[0046] ACC function exit detection: When the ACC system function exits, the LCK function will no longer automatically resume activation. In the next cycle, after ACC is activated, if the driver wants to turn on the lateral function, he needs to re-operate the LCK function switch to activate the lateral control function. During the vehicle following stop stage, the driver can exit the ACC function according to his own needs, such as stepping on the brake pedal, pressing the ACC cancel or function exit button, etc., to exit ACC. Or if the ACC controls the vehicle to stop for more than the maximum time allowed by Stop, the ACC function will also exit.

[0047] Lane line detection and processing when LCK resumes activation: When the vehicle is on an urban road, when the vehicle follows the vehicle in front through a traffic light or intersection, it will stop following the vehicle in front while waiting for the traffic light. After the vehicle in front starts, ACC is reactivated, and when LCK is reactivated, there is no lane line at the traffic light intersection. Therefore, the LCK system is required to fit a lane line based on the motion trajectory of the vehicle in front and the motion state of the vehicle. The present invention uses a 5th-order polynomial to fit the lane center line, which is used for the lane line algorithm in the vehicle starting stage. Detailed algorithm calculation instructions will be provided later.

[0048] LCK function satisfied status detection: When the vehicle is in the following stop stage, LCK also detects the satisfied conditions of the LCK system. When it is detected that the LCK function exit conditions are met, LCK will retain the exit status. During this cycle, LCK will no longer automatically restore the activated status. The driver needs to operate the LCK function switch again to reactivate the LCK function. The LCK exit conditions include but are not limited to the driver stepping on the brake pedal, pulling up the handbrake, and related system EPS, camera failure or occlusion and other conditions.

[0049] The following focuses on fitting the lane centerline using the motion parameters of the vehicle and the target vehicle in front with a 5th-order polynomial. LCK uses the fitted lane centerline to control the vehicle to move along the trajectory of the target vehicle in front. To ensure that the vehicle follows the movement trend of the vehicle in front, ACC controls the longitudinal speed of the vehicle, and LCK controls the lateral movement of the vehicle. This ensures that when the vehicle passes a traffic light intersection, it stops and then restarts after following the vehicle in front, and then follows the vehicle in front through the traffic light intersection. The starting point and end point of the quintic polynomial can be set as: the starting point, the origin of the coordinates of the vehicle, and its related parameters can be obtained based on some sensors of the vehicle, and the end point is the rear protection center point of the target vehicle in front.

[0050] Quintic polynomial: f(x) = C0 + C1x + C2x 2 +C3x 3 +C4x 4 +C5x 5 (1)

[0051] Derivative with respect to x: f'(x) = C1 + 2C2x + 3C3x 2 +4C4x 3 +5C5x 4 (2)

[0052] Find the second derivative with respect to x: f' ‘ (x) = 2C2 + 6C3x + 12C4x 2 +20x 3 (3)

[0053] When x = 0, use the motion parameters at the origin of the vehicle and substitute them to get:

[0054] f(0)=C0=y0=0 (4)

[0055] f'(0)=C1=v y0 (5)

[0056] f”(0)=2C2=a y0 (6)

[0057] Where y0 represents the lateral position error of the vehicle. The starting point of the vehicle's motion planning is the current point of the vehicle, so it is equal to 0;

[0058] For v y0 Represents the lateral speed of the vehicle, which can be obtained through the sensor test of the vehicle;

[0059] For a y0 Represents the lateral acceleration of the vehicle, and this value can also be obtained through the sensor test of the vehicle;

[0060] When x=x pWhen , point p is the motion parameter of the rearward center point of the target vehicle in front. Set point p as the rearward center point of the front vehicle as the end point of the lane line of the fifth-order polynomial. LCK can control the vehicle to move to the corresponding lateral position of the front vehicle according to the current position and follow the movement of the front vehicle. Substitute the relevant motion parameters into the fifth-order polynomial, calculate the first-order derivative and the second-order derivative respectively, and then substitute x=x p :

[0061]

[0062] Derivative with respect to x:

[0063] Find the second derivative with respect to x:

[0064] where y p Represents the lateral position of the rear protection center of the target vehicle in front;

[0065] For v yp Represents the lateral speed of the rear protection center of the front target vehicle;

[0066] For a yp Represents the lateral acceleration of the rear guard center of the front target vehicle;

[0067] These three values ​​can be obtained through testing of sensors such as cameras or front millimeter-wave radars.

[0068] The combined equations (4), (5), (6), (7), (8), and (9) can be used to calculate C3, C4, and C5, as shown below:

[0069]

[0070] Then, the obtained parameters C0, C1, C2, C3, C4, and C5 are substituted into the above formula (1) as the control lane line of the lateral LCK. The LCK controls the vehicle to move according to the fitted quintic polynomial, starting from the current position of the vehicle, moving to the front following target, and reaching the lateral position, lateral speed, and lateral acceleration consistent with the front following target at the front target position, and perfectly follows the front vehicle to cross the intersection after starting at the traffic light position, and the control effect is relatively ideal.

[0071] The present invention combines the state of longitudinal control ACC and utilizes the vehicle state given by ACC during longitudinal control of the vehicle to identify the vehicle's following, stopping and starting, and then optimizes the lateral LCK control function. It also comprehensively considers the stability of the lateral control of the vehicle at low speed and the motion parameters of the vehicle in front to comprehensively control the vehicle laterally, thereby achieving a very ideal effect and increasing the intelligence of the vehicle, making it more convenient to operate the vehicle when following a vehicle on a city road and passing a traffic light intersection.

[0072] After actual vehicle verification, on urban roads, when a vehicle follows the vehicle in front, after turning on the ACC function, the lateral control LCK function is turned on. When following the vehicle in front through places with heavy traffic, or passing through traffic lights, the vehicle in front sometimes stops from driving, waiting for traffic lights or waiting for congested vehicles. At this time, the ACC system of this vehicle will control this vehicle to follow and stop. After LCK detects that ACC has entered the follow and stop state, the LCK function exits and records this exit condition. When the driver determines that the vehicle in front has started and the vehicle can start again, the ACC system can be activated by pressing the accelerator pedal or operating the ACC function recovery switch to control the vehicle to start. After LCK detects this condition, if the driver controls the ACC switch to reactivate ACC, LCK will directly recover and use the lane line fitted by the fifth-order polynomial to control the vehicle to follow the vehicle in front. If the driver restarts the vehicle by controlling the accelerator pedal, the ACC system will also be reactivated. When the driver does not step on the accelerator pedal, ACC controls the vehicle. After LCK detects this condition, it automatically resumes activation. When a lane line is detected, the lane line is used to control the vehicle to drive in the center. When there is no lane line but there is a following vehicle in front, the virtual fifth-order polynomial is used to control the vehicle. This algorithm can well control the vehicle on urban roads or congested roads. After turning on the ACC and LCK lateral control functions, this vehicle frequently stops and starts following the vehicle in front. With as few operations as possible, the vehicle can easily stop and start following the vehicle in front, making the vehicle's assisted driving function more intelligent, saving the driver's pressure on driving on urban roads and congested roads, making the vehicle operation more convenient, and improving the overall performance of the vehicle.

[0073] Although the embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the claims and their equivalents.

Claims

1. A lateral control strategy for low-speed stop and start, characterized in that: The steps include: Obtain the target information output by the front-end sensing device and the vehicle information input by the vehicle, and turn on the longitudinal control ACC and the lateral control LCK function. The LCK system detects the status of the ACC system; When the vehicle speed is less than 0.5km / h or the ACC state enters the Stop state, LCK will process accordingly, that is, when the vehicle speed is less than 0.5km / h, the requested torque or angle will not be output. When the ACC enters the Stop state, the LCK function will exit and record, and monitor the ACC state at the same time; When the ACC state is reactivated and enters the Override state, LCK will not be reactivated. After entering the On state from Override, if there is a lane line, the vehicle will be controlled according to the lane line. If there is no lane line, the vehicle will be controlled according to the fifth-order polynomial fitted by the motion parameters of the preceding vehicle. When the ACC state changes from Override state to SpeedControl state, if there is a lane line, the vehicle will be controlled according to the lane line. If there is no lane line, LCK will not be activated. When the ACC state is exited, the LCK function is exited and will not be automatically restored. The driver needs to press the LCK function switch again to activate it.

2. A lateral control strategy for low-speed stop and start according to claim 1, characterized in that: The following specific steps are also included: Step 1: obtaining target information output by the front-end sensing device and vehicle information input by the vehicle; Step 2: Based on the information in step 1, the driver activates the ACC function and then operates the LCK switch. After LCK determines that the lateral system meets the lateral activation conditions, the system is activated, calculates the torque or steering angle required for the desired lateral control under the current working conditions, controls the vehicle laterally, and monitors the vehicle speed and ACC status.

3. A lateral control strategy for low-speed stop and start according to claim 2, characterized in that: According to the information in step 2, when the vehicle speed is detected to be less than 0.5 km / h, LCK does not output the requested torque or angle. When the ACC state is detected to enter the Stop state, the LCK function exits and records the exit, while monitoring the ACC state.

4. A lateral control strategy for low-speed stop and start according to claim 3, characterized in that: When it is detected that the ACC state is reactivated and enters the Override state, LCK does not resume activation. When the ACC state enters the On state from Override, LCK determines whether there are lane lines. If there are lane lines, it controls the vehicle's lateral direction according to the lane lines to ensure that the vehicle travels within the lane lines.

5. A lateral control strategy for low-speed stop and start according to claim 4, characterized in that: When it is detected that the ACC state is reactivated and enters the Override state, LCK does not resume activation. When the ACC state enters the On state from Override, LCK determines whether there is a lane line. If there is no lane line, the motion parameters of the preceding vehicle are used to fit a fifth-order polynomial. The fitted fifth-order polynomial is used to control the lateral direction of the vehicle to ensure that the vehicle follows the motion trajectory of the preceding vehicle.

6. A lateral control strategy for low-speed stop and start according to claim 5, characterized in that: When it is detected that the ACC state is reactivated and enters the Override state, LCK does not resume activation. When the ACC state enters the SpeedControl state from the Override state, LCK determines whether there are lane lines. If there are lane lines, it controls the vehicle's lateral direction according to the lane lines to ensure that the vehicle travels within the lane lines. When LCK determines that there are no lane lines, LCK is not activated.

7. A lateral control strategy for low-speed stop and start according to claim 6, characterized in that: When it is detected that the ACC state is reactivated and enters the ON state, LCK determines whether there is a lane line. If there is no lane line, it uses the motion parameters of the preceding vehicle to fit a fifth-order polynomial, and uses the fitted fifth-order polynomial to control the lateral direction of the vehicle to ensure that the vehicle follows the motion trajectory of the preceding vehicle.

8. A lateral control strategy for low-speed stop and start according to claim 7, characterized in that: When it is detected that the ACC state is reactivated and enters the SpeedControl state, LCK determines whether there are lane lines. If there are lane lines, it controls the vehicle's lateral direction according to the lane lines to ensure that the vehicle travels within the lane lines; when there are no lane lines, LCK is not activated.

9. A lateral control strategy for low-speed stop and start according to claim 8, characterized in that: When it is detected that the ACC state is exited, the LCK function will exit and will not be automatically restored. When the driver needs the lateral LCK function, he needs to press the LCK function switch again to activate it.

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