Method for controlling lateral position of a vehicle on a traffic lane

Abstract

A method for controlling the lateral position of a vehicle (1) on a traffic lane is disclosed, the method comprising: - a first control step following a first reference trajectory (TR1), and - a step of alerting the driver when the lateral distance of the vehicle from the edge of the traffic lane is less than a first threshold, followed by - a step of detecting a command applied to the steering wheel of the vehicle, followed by - a second control step following a second reference trajectory (TR2) determined as a function of the command applied to the steering wheel, and - a step of alerting the driver when the lateral distance of the vehicle from the edge of the traffic lane is less than a second threshold, the second threshold being less than the first threshold.

Description

Technical Field

[0001] This invention relates to a method for controlling the lateral position of a vehicle in a driving lane. The invention also relates to a motor vehicle including means for implementing this control method. Background Technology

[0002] Lane Centering Assist (LCA) systems are designed to enable autonomous or semi-autonomous vehicles to drive and stay centered in their lane.

[0003] Documents DE102011076418 and EP 2248710 describe this system.

[0004] These systems work in conjunction with detection devices that identify the lateral boundaries of the driving lane and then determine the vehicle's equidistant positioning between these boundaries—that is, centering the vehicle within the driving lane. Using such a system may seem unnatural or inappropriate in certain driving configurations, such as when a truck is in an adjacent lane or when a vehicle veers out of its lane to create passage for a motorcycle or emergency vehicle. During these particular situations, the driver may wish to temporarily veer out of their lane while remaining within the same lane.

[0005] It is known that in "flexible" driver assistance systems, the torque applied to the steering wheel by the driver always affects the vehicle's position within the lane. Therefore, the driver can apply torque to the steering wheel to cause the vehicle to drift towards the edge of the lane. During this maneuver, the assistance system counteracts the driver's request to return the vehicle to the center of the lane. This resistance is uncomfortable, causes anxiety, and can lead to misalignment and / or insufficient safe distance from surrounding vehicles. Furthermore, off-center positioning of the vehicle within the driving lane triggers the playback of warning messages imposed by the standards governing the driver assistance system. These warning messages are also anxiety-inducing and inappropriate.

[0006] WO 03091813 also discloses a guidance system for motor vehicles that collaborates with sensors capable of detecting surrounding objects in adjacent lanes. The vehicle's lateral position is then adjusted based on tracking data of these objects. This method is complex to implement and not satisfactory in all situations. For example, in heavy traffic, the system is susceptible to numerous trajectory changes, which can cause discomfort for passengers.

[0007] Invention Introduction

[0008] The purpose of this invention is to provide a lateral position control method that overcomes the above-mentioned shortcomings and improves upon known control methods in the prior art.

[0009] More precisely, one subject of the present invention is a comfortable, simple to implement, and reassuring method for lateral position control. Summary of the Invention

[0010] This invention relates to a method for controlling the lateral position of a vehicle in a driving lane, the control method comprising:

[0011] -The first step of automatically adjusting the vehicle's lateral position following the first reference trajectory, and

[0012] - A first step of monitoring the lateral distance of the vehicle from the edge of the lane, the first monitoring step including a sub-step of alerting the driver when the lateral distance of the vehicle from the edge of the lane is less than or equal to a first threshold, followed by...

[0013] - The step of detecting the command applied by the driver to the steering wheel of the vehicle to move the vehicle toward the edge of the lane, and then...

[0014] - Stop this first monitoring step.

[0015] - The second step is to automatically control the lateral position of the vehicle following a second reference trajectory, which is determined based on commands applied to the steering wheel by the driver, and

[0016] - A second step of monitoring the lateral distance of the vehicle from the edge of the lane, the second monitoring step including a sub-step of alerting the driver when the lateral distance of the vehicle from the edge of the lane is less than or equal to a second threshold, the second threshold being strictly less than the first threshold.

[0017] The control method may include a sub-step of calculating the first threshold based on the width of the lane and the lateral speed of the vehicle in the lane, and / or the control method may include a sub-step of calculating the second threshold based on the width of the lane and the lateral speed of the vehicle in the lane.

[0018] The control method may include a sub-step of stopping the warning given to the driver when the lateral distance between the vehicle and the edge of the lane is greater than or equal to a third threshold, the third threshold being strictly greater than the first threshold.

[0019] The first control step and / or the second control step may include:

[0020] - A sub-step to calculate the first steering torque of the vehicle's steering wheels.

[0021] - A sub-step to calculate the gain, which is a decreasing function of the torque applied to the steering wheel by the driver.

[0022] - A sub-step to calculate the second steering torque of the vehicle's steering wheels by multiplying the first torque by the gain.

[0023] The control method may include a step of verifying at least one criterion associated with the command, and implementing the step of automatically controlling the vehicle's position according to the second reference trajectory only if the at least one criterion is met. The step of verifying at least one criterion includes:

[0024] - A sub-step that compares the lateral deviation of the vehicle relative to the first reference trajectory with a minimum lateral deviation threshold, and / or

[0025] - A sub-step that compares the lateral deviation of the vehicle relative to the first reference trajectory with a maximum lateral deviation threshold, and / or

[0026] - A sub-step that compares the torque applied to the vehicle's steering wheel with a minimum torque threshold, and / or

[0027] - A sub-step that compares the torque applied to the vehicle's steering wheel with the maximum torque threshold.

[0028] The control method may include a step of determining the lateral offset of the vehicle relative to a first reference trajectory after the driver applies the command to the steering wheel, the second reference trajectory being defined based on the first reference trajectory and the lateral offset, the determining step including detecting an increase in torque applied to the steering wheel by the driver and subsequent stabilization and / or detecting an increase in the vehicle's state parameters and subsequent stabilization.

[0029] The second control step may include:

[0030] - The steps to calculate the reference state vector of the vehicle.

[0031] - The steps to calculate the observed state vector of the vehicle.

[0032] - The step of calculating the steering angle setpoint of the vehicle's steering wheels based on the difference between the reference state vector and the observed state vector.

[0033] - A transitional step performed at the start of the second control step, which includes replacing the components of the vehicle's observed state vector with the calculated components, such that the steering angle setpoints of the vehicle's steering wheels are equal to the current values ​​of the steering angles of those steering wheels.

[0034] The control method may include:

[0035] - Hold this second control step temporarily, then automatically,

[0036] - The third step is to automatically control the vehicle's position following the first reference trajectory.

[0037] The present invention also relates to a computer program product comprising program code instructions recorded on a computer-readable medium for implementing the steps of the control method as defined above when the program is run on a computer.

[0038] Finally, the present invention also relates to a motor vehicle including a steering wheel connected to a steering wheel, a device for detecting the vehicle environment, a device for alerting the driver, and at least one computer configured to implement the control method as defined above. Attached Figure Description

[0039] These subjects, features, and advantages of the invention will be explained in detail in the following description of specific embodiments given in a non-limiting manner with reference to the accompanying drawings, in which:

[0040] Figure 1 This is a schematic diagram of a motor vehicle according to an embodiment of the present invention.

[0041] Figure 2 This is a diagram of vehicles on the driving lane.

[0042] Figure 3 This is a block diagram of a method for controlling the lateral position of a vehicle in a driving lane according to an embodiment of the present invention.

[0043] Figure 4 This is a schematic diagram of the controller used in the step of controlling the lateral position of the vehicle.

[0044] Figure 5 It is an animated diagram demonstrating how to warn the driver when a vehicle is drifting laterally.

[0045] Figure 6 It is a parameterized graph showing the first threshold.

[0046] Figure 7 This is a parameterized graph showing the second threshold. Detailed Implementation

[0047] Figure 1 A motor vehicle 1 according to an embodiment of the present invention is schematically shown. Vehicle 1 can be any type of vehicle, particularly a passenger car, multi-purpose vehicle, truck, or bus. Vehicle 1 includes two front steering wheels 2f and two rear wheels 2r. The orientation of the steering wheels 2f can be controlled by a steering system 3. The steering system 3 includes a steering device 4 mechanically connected to the two front wheels 2f and a steering wheel 5 mechanically connected to the steering device 4. The steering system 3 may also include an auxiliary steering module, which is, for example, integrated into the steering device 4. The steering system 3 further includes an electronic control unit 6.

[0048] Vehicle 1 also includes devices 8 for detecting the environment of vehicle 1, such as radar and / or lidar and / or cameras. It also includes devices 9 for alerting the driver. These alerting devices can be any devices designed to alert the driver's senses: for example, visual alerting devices capable of displaying symbols or messages, such as indicator lights or screens. These alerting devices can also be audible alerting devices or even vibration alerting devices.

[0049] The electronic control unit 6 is electrically connected to the steering equipment 4, the detection device 8, and the warning device 9. It can also be directly or indirectly connected to other sensors in the vehicle, such as the steering wheel angle sensor, speed sensor, vehicle yaw sensor, or a sensor of the torque applied to the steering wheel 5 by the driver.

[0050] Specifically, the electronic control unit 6 includes a memory, a microprocessor, and input / output interfaces for receiving data from or transmitting data to other devices in the vehicle 1. The memory of the electronic control unit is a medium for recording data, on which a computer program is recorded, including program code instructions for implementing a method according to an embodiment of the invention. The microprocessor is capable of executing the method. Specifically, the electronic control unit 6 is capable of sending control commands to the steering device 4 via its input / output interfaces to apply torque intended to orient the steering wheels 2f. Therefore, the vehicle 1 is an autonomous or semi-autonomous vehicle, i.e., it can be guided and maintained on a steering track without driver intervention. The vehicle 1 can also be controlled by a driver in a conventional manner by actuating the steering wheel. Note that in this document, the “torque” applied to the steering wheels refers to the useful torque used to orient the steering wheels and thus guide the vehicle. Therefore, this term does not refer to the useful engine torque used to turn the wheels to propel the vehicle.

[0051] Figure 2 A vehicle 1 is shown traveling on lane 10. The lane is designed to accommodate a single vehicle across its width. Lane 10 is defined to the left and right by two edges, BG and BD. These edges can be embodied as dividing lines, such as continuous white or yellow lines or dashed lines. In variations, edges BG and BD can simply correspond to the lateral ends of the lane and be embodied by sidewalks, embankments, or simply the edges of the road surface. The roadway on which vehicle 1 travels may include multiple lanes located to the left and / or right of lane 10.

[0052] Figure 2The diagram also shows dashed lines LS1G, LS2G, LS3G, LS1D, LS2D, LS3D, and LM. These lines are not specifically depicted on the driving lane but are simply shown for clarity of the invention. Lines LS1G, LS2G, and LS3G are substantially parallel to the left edge BG and are respectively separated from it by thresholds S1, S2, and S3. Similarly, lines LS1D, LS2D, and LS3D are substantially parallel to the right edge BD and are respectively separated from it by thresholds S1, S2, and S3. Line LM extends equidistantly from edges BG and BD. In other words, line LM is the centerline of driving lane 10. Note that... Figure 2 The driving lane shown is a straight line. However, the invention can also be implemented when the driving lane describes a curve or bend.

[0053] The detection device 8 is able to identify the edges BG and BD of the driving lane 10 and determine the lateral position of the vehicle 1 in the driving lane. The lateral position of the vehicle can be determined, for example, by quantifying the lateral distance D (or lateral deviation D) between the left edge of the vehicle and the left edge BG of the driving lane.

[0054] In this document, the longitudinal axis is defined as the lane axis at the height of vehicle 1. Therefore, the longitudinal axis can be substantially parallel to edges BG and BD. Assuming edges BG and BD are not strictly parallel, the longitudinal axis can represent the bisector of these two lines at the height of vehicle 1. The longitudinal axis can also correspond to an axis that is parallel only to one of the two edges BG or BD. The lateral axis is the lane axis perpendicular to the longitudinal axis. The adjective "lateral" characterizes an object along the lateral axis. Therefore, the lateral position of a vehicle represents its position along the lateral axis.

[0055] Now refer to Figure 3 An embodiment of a method for controlling the lateral position of a vehicle 1 on a driving lane 10 is described.

[0056] In the first step E1, automatic control of the vehicle position is performed following a first reference trajectory TR1. The first reference trajectory can be defined essentially at the center of the driving lane. Therefore, it can correspond to the center line LM. In other words, the lateral position of the vehicle is controlled to follow the center line LM.

[0057] Automatic control of the vehicle's lateral position following the reference trajectory TR1 can be achieved through, for example... Figure 4The closed-loop algorithm is schematically illustrated in the diagram and executed accordingly. Therefore, the first control step E1 includes: a sub-step E11 of calculating the vehicle's reference state vector Xref; a sub-step E12 of calculating the vehicle's observed state vector Xobs; and a sub-step E13 of calculating the steering angle setpoint δc of the vehicle's steering wheels based on the difference between the reference state vector Xref and the observed state vector Xobs. Subsequently, during subsequent iterations of the first step E1, the observed state vector Xobs is calculated using the steering angle setpoint δc.

[0058] The reference state vector Xref describes the vehicle's desired position and trajectory. Specifically, this state vector can be calculated based on the first reference trajectory TR1 (i.e., the centerline LM). Because the vehicle 1 is subjected to various disturbances caused by factors both internal and external to the vehicle 1, the reference state vector Xref at a given moment may differ from the vehicle's observed state vector Xobs. These internal or external factors can be, for example, changes in vehicle grip, load variations, road deformation, the effects of wind, or the accuracy of the detection device 8.

[0059] This can be obtained from sensors installed in the vehicle, particularly from detection device 8, and from the vehicle's kinematic model (in... Figure 4 (identified by 11) and observer (in) Figure 4 The observation state vector Xobs is calculated using the 12-character identifier. The observation state vector Xobs may include all or some of the following seven components:

[0060] - Vehicle yaw speed, and / or

[0061] - The vehicle's heading angle, and / or

[0062] - The vehicle's lateral speed, and / or

[0063] - Lateral deviation of the vehicle relative to the reference trajectory, and / or

[0064] - The steering speed of the vehicle's steering wheels, and / or

[0065] - The steering angle of the vehicle's steering wheels, and / or

[0066] - The integral of the lateral deviation of the vehicle relative to the reference trajectory.

[0067] Then, the first control step E1 includes a sub-step E14 during which a first torque C1 is calculated. This first torque C1 is calculated based on the previously calculated steering angle setpoint δc and by the PID controller 13 (i.e., a proportional-integral-derivative controller).

[0068] The first control step E1 further includes a sub-step E15, during which a gain K1 between 0 and 1 is calculated. Advantageously, the gain K1 can be a decreasing function of the torque applied by the driver to the steering wheel 5. In other words, the higher the torque applied by the driver to the steering wheel 5, the lower the gain K1.

[0069] Finally, the first control step E1 includes sub-step E16, in which the torque C2 to be applied to the steering wheel 2f is calculated by multiplying the torque C1 by the gain K1. The torque C2 thus obtained can then be provided to the steering device 4 to orient the steering wheel.

[0070] Therefore, vehicle 1 can be controlled according to several operating modes: In the first mode, called manual mode and corresponding to a gain K1 value of 0, the orientation of the steering wheels 2f is controlled solely by the driver. In the second mode, corresponding to a gain K1 value of 1, the torque C2 transmitted to the steering wheels is sufficient to follow the first reference trajectory. Finally, in the third operating mode, where the gain K1 is between 0 and 1 (excluding 1), the torque C2 transmitted to the steering wheels is insufficient to follow the first reference trajectory. However, the driver feels the torque C2 by gripping the steering wheel, and this torque is interpreted as a cue to orient the steering wheel to follow the first reference trajectory TR1. The actual steering torque applied to the steering wheels 2f is then generated by adding the torque C2 and the torque transmitted to the steering wheels through the driver's actions on the steering wheel. As long as the gain K1 is strictly greater than 0, control of the vehicle's lateral position is considered automatic.

[0071] In parallel with the first control step E1, the method includes a first step E2 that monitors the lateral distances of the vehicle from the edges BG and BD of the driving lane.

[0072] The first monitoring step E2 first includes a sub-step E21 that calculates a first threshold S1. Specifically, the first threshold S1 can be calculated based on the width of the lane 10 and the lateral speed of the vehicle 1 on the lane 10. The first threshold can be determined to provide a standard for imposing driver warnings in the event of vehicle drift. The width of the lane can be the distance from the edge BG to the BD of the lane at the height of the vehicle 1 or at a given distance in front of the vehicle 1. It can be calculated by the detection device 8. The lateral speed of the vehicle 1 represents the speed of the vehicle along the lateral axis Y, i.e., the speed at which the vehicle approaches the edge BG or BD. Figure 6An example of the mapping for the first threshold S1 is shown. Axis X1 represents the lane width, for example, between 2.5m and 4m. Axis Y1 represents the lateral speed of vehicle 1 in absolute value, for example, between 0 and 1.8m / s. Axis Z1 represents the obtained threshold S1, which may be between, for example, approximately 10cm and 30cm. Threshold S1 can be an increasing function of both the lateral speed and the lane width. Advantageously, the threshold S1 is the same for the left and right sides of the lane, but in variations, the threshold can also be different.

[0073] The first monitoring step E2 includes a sub-step E22 that alerts the driver when the lateral distance between the vehicle and the edge of the lane (BD or BG) becomes less than or equal to a previously calculated first threshold (S1). The driver is alerted by activating the warning device 9. Therefore, the driver is warned that the steering device 4's action on the steering wheels 2f is insufficient to follow the first reference trajectory TR1. Consequently, the driver can then take action with the steering wheel 5 to bring the vehicle back to the center of the lane. Thus, the regulatory requirement to alert the driver when the vehicle is too close to the edge of the lane is met.

[0074] In the third sub-step E23, when the lateral distance between the vehicle and the edge BD or BG of the driving lane is greater than or equal to the third threshold S3, the warning given to the driver is stopped. The third threshold S3 is strictly greater than the first threshold S1. The third threshold S3, which can be referred to as the reset threshold, can be defined according to the width of the driving lane and its curvature. Therefore, untimely activation and deactivation of the warning device 9 are avoided.

[0075] When the vehicle's position is controlled to follow a first reference trajectory, the driver may wish to veer their vehicle to one side of the driving lane to anticipate any form of risk. For example, if the driver is overtaking a truck on the left, they may wish to veer their vehicle to the left of the driving lane to increase the lateral distance between their vehicle and the truck. If a motorcycle or emergency vehicle is preparing to overtake the vehicle on the left, the driver may wish to veer their vehicle to the right to leave sufficient passage. The driver may also wish to veer their vehicle simply to improve their visibility of the road ahead relative to vehicles in the driving lane. To veer their vehicle, the driver therefore applies a command in the form of torque applied to the steering wheel 5 to guide their vehicle in the desired direction.

[0076] The control method then includes step E3, which detects a command applied to the steering wheel 5 by the driver. The lateral deviation of the vehicle relative to a first reference trajectory and the torque applied to the steering wheel 5 are then observed. As will be seen below, the lateral deviation relative to the reference trajectory serves as the basis for defining a second reference trajectory TR2. Prior to this, detection step E3 may include a sub-step E31 that verifies various criteria associated with the command applied by the driver.

[0077] Verification step E31 may include a sub-step E311 that compares the vehicle's lateral deviation with a minimum lateral deviation threshold. This minimum threshold (which may be fixed, for example, at 10 cm) allows unintentional movements of the driver relative to the first reference trajectory TR1 to be filtered out. Therefore, as long as the driver's actions on the steering wheel cause the vehicle's deviation from the reference trajectory to be less than 10 cm, the first control step E1 will continue, and the vehicle will continue to follow the first reference trajectory TR1.

[0078] Verification step E31 may further include a sub-step E312 comparing the vehicle's lateral deviation with a maximum lateral deviation threshold. This maximum threshold can be defined based on the vehicle's lateral acceleration, the vehicle's speed, the lane width, and the vehicle's width. Specifically, the maximum threshold can be an increasing function of the lane width and / or a decreasing function of the vehicle width, vehicle speed, and lateral acceleration. By defining the maximum threshold, excessive offset of the second reference trajectory relative to the center of the lane is prevented. Therefore, if a driver's command results in excessive lateral deviation, the command will not lead to the definition of the second reference trajectory.

[0079] Verification step E31 may further include a sub-step E313 comparing the torque applied to the steering wheel with a minimum torque threshold. This minimum threshold can be defined based on the vehicle's longitudinal speed and the curvature of the driving lane. Therefore, the minimum threshold may include, for example, between 0.8 Nm and 1.6 Nm. In a variant, the minimum torque threshold may be equal to a fixed value, for example, defined as 1.5 Nm. This minimum torque threshold allows for filtering out unintentional movements of the driver on the steering wheel. For example, if one of the driver's hands temporarily releases the steering wheel, a small change in torque transmitted to the steering wheel can be detected; however, this does not correspond to the driver's intention to deviate from the vehicle. Nevertheless, the first control step E1 continues, and the vehicle continues to follow the first reference trajectory.

[0080] The verification step E31 may also include a sub-step E314 that compares the torque applied to the vehicle's steering wheel with a maximum torque threshold. This maximum torque threshold may, for example, be defined as 4 Nm. If the driver applies such torque to the steering wheel, which can be interpreted as an emergency command, particularly an evasive maneuver, the control method can be deactivated to allow the driver full control of the vehicle's direction.

[0081] A time period can be applied to each of substeps E311, E312, E313, and E314 to ensure the criterion is validated within a minimum duration. For example, a low-frequency filter can be used to filter vehicle lateral deviation measurements and / or torque applied to the steering wheel. A counter can also be used, and this can be verified by observing it over a sufficiently large number of iterations of the method.

[0082] If all criteria verified during verification step E31 are met, the lateral deviation between vehicle 1 and the first reference trajectory can be stored and used as the lateral offset OL for defining the second reference trajectory TR2. Therefore, the second reference trajectory TR2 is substantially parallel to the first reference trajectory TR1 and offset from it by the value of the lateral offset OL. Thus, detection step E3 may include a sub-step E32 determining the lateral offset OL. This determining step E32 may include detecting an increase in torque applied to the steering wheel by the driver and subsequent stabilization. The lateral offset corresponds to the lateral deviation obtained after the torque applied to the steering wheel stabilizes. The torque can be considered stable when it becomes less than or equal to a threshold defined by parameterization (e.g., a value of approximately 0.7 Nm). Deactivation of the control method can also be provided if the torque becomes unstable at the end of a duration defined by parameterization (e.g., a duration of approximately 10 seconds). In a variant, the lateral offset can also be determined by observing an increase in another state parameter of the vehicle and subsequent stabilization. This state parameter may be, for example, the lateral deviation relative to the first reference trajectory TR1, the vehicle's heading angle, or the vehicle's lateral velocity.

[0083] Finally, the lateral offset (OL) is defined by the driver's actions on the steering wheel. Therefore, it is a result of driver selection, not an automatically defined one. Consequently, drivers can freely define the lateral offset value of their vehicle according to their needs and traffic conditions.

[0084] Next, in the second control step E4, the vehicle's position is automatically controlled following the second reference trajectory TR2. This step is, of course, implemented only if the criteria tested during verification step E31 are met.

[0085] The lateral position control of the vehicle following the second reference trajectory TR2 can be performed in the same manner as the lateral position control following the first reference trajectory TR1. Therefore, the second control step E4 may include sub-steps E41, E42, E43, E44, E45, and E46, which are identical to the aforementioned steps E11, E12, E13, E14, E15, and E16, except that the first reference trajectory TR1 is replaced by the second reference trajectory TR2. Therefore, the driver can follow the second reference trajectory TR2 without having to apply torque to the steering wheel to counteract the torque generated by the steering device 4 that tends to return the vehicle to the first reference trajectory TR1. Thus, the guidance of vehicle 1 is more pleasant and precise.

[0086] Parallel to the second control step E4, the method includes a second step E5 that monitors the lateral distance of the vehicle from the edges BG and BD of the driving lane. The second monitoring step E5 is also performed in a manner similar to the first monitoring step E2. Therefore, it includes sub-steps E51, E52, and E53 corresponding to the aforementioned sub-steps E21, E22, and E23. However, the difference between the second monitoring step E5 and the first monitoring step E1 is that the first threshold S1 is replaced by a second threshold S2 that is strictly less than the first threshold S1. In other words, during the second control step E4, the vehicle is allowed to move closer to the edge BG or BD before triggering a driver warning. This allows for the avoidance of triggering an inappropriate driver warning, as the vehicle's deviation is intentional. However, if the vehicle is too close to the lateral edges BG or BD, the warning device remains active. The warning given to the driver during step E52 can be the same as the warning given to the driver during step E22. In variations, the warning can be different, for example, more intense, depending on the proximity to the edges BG or BD of the driving lane.

[0087] Once the second monitoring step E5 is activated, the first monitoring step E2 stops. This transition between the two monitoring steps can occur when the criteria tested during verification step E31 are met. Therefore, at any given time there is at least one threshold S1 or S2 that generates a driver warning when exceeded.

[0088] Figure 7 An example of mapping the second threshold S2 is shown. Axis X1 represents the lane width, for example, between 2.5m and 4m. Axis Y1 represents the lateral speed of vehicle 1 approaching the edge in question, for example, between 0 and 1.8m / s. Axis Z1 represents the obtained threshold S2, which can be, for example, between approximately 0 and 20cm. Threshold 2 can be an increasing function of both the lateral speed and the lane width. Advantageously, the threshold S2 is the same for the left and right sides of the lane, but in variations, the threshold can also be different. Note that threshold S2 is independent of the lateral offset OL.

[0089] In addition to alerting the driver when thresholds S1 or S2 are exceeded, a step can be provided to automatically return the vehicle to the center to re-establish lateral distances from the edges BG or BD that are respectively strictly greater than thresholds S1 or S2.

[0090] Figure 5 A method for alerting the driver in the event of lateral drift of the vehicle is demonstrated. State P1 corresponds to the activation state of the method for controlling the lateral position of the vehicle. Based on state P1, a first test V1 is performed, which determines whether the vehicle has reached a first threshold S1, or in other words, whether one of its edges has reached one of lines LS1G or LS1D. If the lateral distance of the vehicle from edge BD or BG remains strictly greater than the threshold S1, the vehicle remains in state P2 without issuing a warning. On the other hand, if the lateral distance becomes less than or equal to the threshold S1, a second test V2 is performed, which determines whether torque is applied to the vehicle's steering wheel 5. If torque is applied to the vehicle's steering wheel 5, the vehicle remains in state P2 without issuing a warning. Conversely, if no torque is applied to the vehicle's steering wheel 5, the vehicle enters state P3, which triggers a driver warning. Based on state P2, a third test V3 is performed, which determines whether the vehicle has reached a second threshold S2, or in other words, whether one of its edges has reached one of lines LS2G or LS2D. If the lateral distance of the vehicle from edge BD or BG remains strictly greater than the threshold S2, the vehicle remains in state P2 without issuing a warning. On the other hand, if the lateral distance becomes less than or equal to the threshold S2, the vehicle enters state P3, which triggers a driver warning.

[0091] In other words, if threshold S1 is reached, the driver is alerted only when no torque is applied to the steering wheel. If threshold S2 is reached, the driver is alerted in all situations.

[0092] Based on state P3, the fourth test V4 is performed to determine whether the vehicle has reached the third threshold S3, or in other words, whether the vehicle has returned to the space defined between lines LS3G and LS3D. If this is not the case, the driver alert is maintained. If this is indeed the case, the driver alert is deactivated.

[0093] According to the original aspect of the invention, the second control step E4 includes a transition step E40 executed at the beginning of the second control step E4. The transition step E40 aims to provide a smooth transition between the two reference trajectories TR1, TR2, without overshoot or abrupt changes. The transition step E40 includes replacing the components of the vehicle's observed state vector Xobs with calculated components such that the steering angle setpoint δc of the vehicle's steering wheels is equal to the current value of the steering angle δm, i.e., the value of the steering angle of the steering wheels measured at the time of execution of the transition step E40. Specifically, the components of the state vector corresponding to the integral of the lateral deviation of the vehicle relative to the reference trajectory can be replaced by values ​​calculated in such a way that the steering angle setpoint δc of the vehicle's steering wheels is equal to the current value of the steering angle δm.

[0094] With the help of this invention, drivers can effortlessly steer their vehicles out of the lane without inappropriately triggering location warnings.

[0095] According to another specific feature of the invention, the control method includes temporarily holding the second control step E4, and then automatically maintaining the vehicle's position according to the first reference trajectory TR1 in a third step E6. The second control step R4 can be held for a predefined duration calibrated. This duration can correspond to the average duration of an overtaking maneuver, for example, at least ten seconds. In a variant, after detecting the end of the overtaking maneuver, a return to the first reference trajectory can be automatically triggered. Therefore, at the end of the predefined duration, the vehicle can automatically return to the center position on the driving lane according to the first reference trajectory. Advantageously, a transition step similar to the transition step E40 described above can be provided to allow for changes in the reference trajectory without abrupt changes.

[0096] During control, the vehicle's lateral position may fluctuate along the reference trajectory. These fluctuations can be approximately 10 cm and may be caused by various internal or external factors as mentioned above. A safety margin, parameterized as a function of the vehicle speed, can be defined. Advantageously, a second reference trajectory TR2 is defined by taking this safety margin into account. Therefore, the second reference trajectory can be defined at a distance from line LS2G or LS2D that is at least greater than or equal to the safety margin.

Claims

1. A method for controlling the lateral position of a vehicle (1) on a driving lane (10), characterized in that, The method includes: - The first control step (E1) automatically controls the lateral position of the vehicle following the first reference trajectory (TR1), and - A first monitoring step (E2) monitors the lateral distance of the vehicle from the edge of the lane (BD, BG), the first monitoring step including a sub-step (E22) that alerts the driver when the lateral distance of the vehicle from the edge of the lane is less than or equal to a first threshold (S1), followed by... - The step (E3) of detecting the command (5) applied by the driver to the steering wheel of the vehicle to move the vehicle toward the edge of the lane, followed by - Stop the first monitoring step (E2). - A second control step (E4) automatically controls the lateral position of the vehicle following a second reference trajectory (TR2), which is determined based on commands applied to the steering wheel by the driver, and - A second monitoring step (E5) to monitor the lateral distance of the vehicle from the edge of the lane, the second monitoring step including a sub-step (E52) to alert the driver when the lateral distance of the vehicle from the edge of the lane is less than or equal to a second threshold (S2), the second threshold (S2) being strictly less than the first threshold (S1). The method includes a sub-step (E21) of calculating the first threshold (S1) based on the width of the lane and the lateral speed of the vehicle in the lane, and / or the method includes a sub-step (E51) of calculating the second threshold (S2) based on the width of the lane and the lateral speed of the vehicle in the lane.

2. The method as described in claim 1, characterized in that, The method includes sub-steps (E23, E53) to stop giving a warning to the driver when the lateral distance between the vehicle and the edge of the lane is greater than or equal to a third threshold (S3), which is strictly greater than the first threshold (S1).

3. The method as described in claim 1 or 2, characterized in that, The first control step (E1) and / or the second control step (E4) includes: - Sub-steps (E14, E44) to calculate the first steering torque (C1) of the steering wheel (2f) of the vehicle. - Sub-steps (E15, E45) to calculate the gain (K1), which is a decreasing function of the torque applied to the steering wheel by the driver. - Sub-steps (E16, E46) to calculate the second steering torque (C2) of the vehicle's steering wheels by multiplying the first steering torque (C1) and the gain (K1).

4. The method as described in claim 1 or 2, characterized in that, The method includes a step (E31) of verifying at least one criterion associated with the command, and a step of automatically controlling the vehicle's position according to the second reference trajectory (TR2) is implemented only if the at least one criterion is met. The step of verifying the at least one criterion includes: - A sub-step (E311) that compares the lateral deviation of the vehicle relative to the first reference trajectory (TR1) with a minimum lateral deviation threshold, and / or - A sub-step (E312) that compares the vehicle's lateral deviation relative to the first reference trajectory (TR1) with a maximum lateral deviation threshold, and / or - A sub-step (E313) that compares the torque applied to the vehicle's steering wheel with a minimum torque threshold, and / or - A sub-step (E314) that compares the torque applied to the steering wheel of the vehicle with the maximum torque threshold.

5. The method as described in claim 1 or 2, characterized in that, The method includes a determination step (E32) after the driver applies the command to the steering wheel to determine the lateral offset (OL) of the vehicle relative to the first reference trajectory (TR1), the second reference trajectory (TR2) being defined based on the first reference trajectory (TR1) and the lateral offset (OL), the determination step including detecting an increase in torque applied to the steering wheel by the driver and subsequent stabilization and / or detecting an increase in the vehicle's state parameters and subsequent stabilization.

6. The method as described in claim 1 or 2, characterized in that, The second control step (E4) includes: - Step (E41) to calculate the reference state vector (Xref) of the vehicle (1). - Step (E42) to calculate the observed state vector (Xobs) of the vehicle (1). - The step (E43) to calculate the steering angle setpoint (δc) of the steering wheel (2f) of the vehicle (1) based on the difference (Xerr) between the reference state vector (Xref) and the observed state vector (Xobs). - A transition step (E40) is performed at the beginning of the second control step (E4), which includes replacing the components of the vehicle's observed state vector (Xobs) with the calculated components, such that the steering angle setpoint (δc) of the vehicle's steering wheels (2f) is equal to the current value of the steering angle (δm) of those steering wheels.

7. The method as described in claim 1 or 2, characterized in that, The method includes: - Hold this second control step (E4) temporarily, then automatically, - The third step (E7) is to automatically control the position of the vehicle following the first reference trajectory (TR1).

8. A computer program product comprising program code instructions recorded on a computer-readable medium, the program code instructions being used to perform the steps of the method as described in any of the preceding claims when the program is run on a computer.

9. A motor vehicle (1), characterized in that, The motor vehicle includes a steering wheel (2f) connected to a steering wheel (5), a device (8) for detecting the environment of the vehicle, a device (9) for alerting the driver of the vehicle, and at least one computer (6) configured to implement the method as described in any one of claims 1 to 7.

Images