Method for controlling the lateral position of a vehicle in a driving lane.

Abstract

A method for controlling the lateral position of a vehicle (1) on a driving lane is disclosed, the method comprising: - a first control step of following a first reference trajectory (TR1); - a step of warning the driver when the lateral distance separating the vehicle from the edge of the driving lane becomes shorter than a first threshold; then - a step of detecting commands applied to a steering wheel of the vehicle; then - a second control step of following a second reference trajectory (TR2) determined in response to the commands applied to the steering wheel; and - a step of warning the driver when the lateral distance separating the vehicle from the edge of the driving lane becomes shorter than a second threshold, the second threshold being shorter than the first threshold.

Description

Technical Field

[0001] The present invention relates to a method for controlling the lateral position of a vehicle on a driving lane. The present invention also relates to a motor vehicle comprising means for carrying out such a control method.

Background Art

[0002] Lane centering assist (LCA) systems are intended to drive autonomous or semi-autonomous vehicles and keep them in the center of the lane they are traveling on.

[0003] Documents DE102011076418 and EP 2248710 describe such systems.

[0004] These systems cooperate with detection means that can identify the lateral limits of the driving lane and then determine an equidistant positioning of the vehicle between these two lateral limits, i.e., the positioning of the vehicle at the center of the driving lane. The use of such systems seems unnatural or inappropriate under certain driving scenarios, such as when a truck is driving in an adjacent lane or when offsetting the vehicle within the lane to create a passage for a motorcycle or an emergency vehicle. During these specific situations, the driver may want to temporarily offset their vehicle while maintaining the same driving lane.

[0005] A "flexible" assist system is known in which the torque applied to the steering wheel by the driver constantly influences the vehicle's position within the lane. Therefore, the driver can apply torque to the steering wheel to offset their vehicle towards the edge of the lane. During this maneuver, the assist system will return the vehicle towards the center of the lane against the driver's request. Such resistance is unpleasant, unsettling, and can lead to incorrect positioning and / or insufficient safety distance from surrounding vehicles. Furthermore, abnormal positioning of the vehicle within the lane will result in the broadcasting of warning messages mandated by the standards governing the driver assistance system. Such warning messages are also unsettling and inappropriate.

[0006] Patent application WO03091813 also discloses a guidance system for an automated vehicle that works in cooperation with sensors capable of detecting surrounding objects in adjacent lanes. In this case, the lateral position of the vehicle is adapted based on tracking data of these objects. Such a method is complex to implement and is not necessarily satisfactory in all situations. For example, in congested traffic, the system is subjected to many trajectory changes, which could result in an unpleasant experience for passengers. [Overview of the project]

[0007] The object of the present invention is to provide a lateral position control method that overcomes the above-mentioned drawbacks and improves upon control methods known in the prior art.

[0008] More precisely, one of the subjects of the present invention is a method for controlling lateral position that is comfortable, easy to implement, and provides a sense of security.

[0009] The present invention relates to a method for controlling the lateral position of a vehicle on a driving lane, and the control method is: - A first step of automatically adjusting the lateral position of a vehicle following a first reference track, - A first step of monitoring the lateral distance separating the vehicle from the edge of the driving lane, the first monitoring step includes a substep of warning the driver when the lateral distance separating the vehicle from the edge of the driving lane falls below a first threshold, and then, - A step of detecting a command applied by the driver to the steering wheel of the vehicle to shift the vehicle toward the edge of the driving lane, and then, - A step to stop the first monitoring step, - A second step of automatically controlling the lateral position of a vehicle following a second reference track, wherein the second track is determined based on a command applied to the steering wheel by the driver, - A second step of monitoring the lateral distance separating the vehicle from the edge of the driving lane, the second monitoring step includes a substep of warning the driver when the lateral distance separating the vehicle from the edge of the driving lane falls below a second threshold, the second threshold being strictly shorter than the first threshold, and Includes.

[0010] The control method may include a substep of calculating a first threshold based on the width of the driving lane and the lateral speed of vehicles in the driving lane, and / or the control method may include a substep of calculating a second threshold based on the width of the driving lane and the lateral speed of vehicles in the driving lane.

[0011] The control method may include a substep of deactivating a warning given to the driver when the lateral distance separating the vehicle from the edge of the driving lane exceeds a third threshold, the third threshold being strictly longer than the first threshold.

[0012] The first control step and / or the second control step is: - A substep to calculate the first steering torque of the vehicle's steering wheels, - A substep to calculate the gain, which is a decrease function of the torque applied to the steering wheel by the driver, - A substep to calculate the second steering torque of the vehicle's steering wheels by multiplying the first torque by the gain. It can include...

[0013] The control method may include a step of verifying at least one criterion related to the command, the step of automatically controlling the position of a vehicle following a second reference track is performed only if the at least one criterion is met, and the step of verifying at least one criterion is, - A substep of comparing the lateral deviation of the vehicle relative to a first reference track with a minimum lateral deviation threshold, and / or - A substep of comparing the lateral deviation of the vehicle relative to a first reference track with a maximum lateral deviation threshold, and / or - A substep of comparing the torque applied to the vehicle's steering wheel with a minimum torque threshold, and / or - A substep that compares the torque applied to the vehicle's steering wheel with the maximum torque threshold. Includes.

[0014] The control method may include the step of determining the lateral offset of the vehicle with respect to a first reference trajectory, following a command applied to the steering wheel by the driver, the second reference trajectory being defined based on the first reference trajectory and the lateral offset, and the step of determining this includes detecting an increase in torque applied to the steering wheel by the driver, followed by detection of stabilization following that increase, and / or detecting an increase in a vehicle state parameter, followed by detection of stabilization following that increase.

[0015] The second control step is: - A step of calculating the vehicle's reference state vector, - A step of calculating the observed state vector of the vehicle, - A step of calculating the setpoint for the steering angle of the vehicle's steering wheels based on the difference between the reference state vector and the observed state vector, - A transition step executed at the start of the second control step, including replacement of a component of the vehicle's observed state vector with a component calculated such that the steering angle setpoint of the vehicle's steering wheel equals the current value of the steering angle of the steering wheel. It can include.

[0016] The control method - A step of temporarily maintaining the second control step, and then automatically - A third step of automatically controlling the position of a vehicle following a first reference trajectory It can include.

[0017] The present invention also relates to a computer program product including program code instructions recorded on a computer-readable medium, which, when the program is executed on a computer, implements the steps of the control method defined above.

[0018] Finally, the present invention also relates to a motor vehicle comprising a steering wheel connected to a steering handle, means for detecting the vehicle's environment, means for warning the vehicle's driver, and at least one computer configured to execute the control method defined above.

[0019] These subjects, features and advantages of the present invention are explained in detail in the following description of specific embodiments given in a non-limiting manner with reference to the accompanying drawings.

Brief Description of the Drawings

[0020] [Figure 1] It is a schematic diagram of a motor vehicle according to an embodiment of the present invention. [Figure 2] It is a schematic diagram of a vehicle on a driving lane. [Figure 3] It is a block diagram of a method for controlling the lateral position of a vehicle on a driving lane according to an embodiment of the present invention. [Figure 4] It is a schematic diagram of a controller used in the step of controlling the lateral position of a vehicle. [Figure 5] This is a diagram of an activity that shows how to warn the driver if the vehicle drifts sideways. [Figure 6] This graph shows the parameterization of the first threshold. [Figure 7] This graph shows the parameterization of the second threshold. [Modes for carrying out the invention]

[0021] Figure 1 schematically shows an automated vehicle 1 according to one embodiment of the present invention. Vehicle 1 may be of any type, in particular a passenger car, utility vehicle, truck, or bus. Vehicle 1 is equipped with two steering front 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 is equipped with 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 be equipped with an assisted steering module integrated into, for example, the steering device 4. The steering system 3 further comprises an electronic control unit 6.

[0022] Vehicle 1 also includes means 8 for detecting the environment of Vehicle 1, such as radar and / or lidar and / or cameras. Vehicle 1 also includes means 9 for warning the driver. These warning means may be any means intended to warn the driver's senses, and may be visual warning means such as indicator lights or screens that can display symbols or messages. These warning means may be audible warning means, or even vibration warning means.

[0023] The electronic control unit 6 is electrically connected to the steering device 4, the detection means 8, and the warning means 9. The electronic control unit 6 may also be directly or indirectly connected to other vehicle sensors, such as the vehicle's steering angle sensor, speed sensor, roll sensor, or a torque sensor applied by the driver to the steering wheel 5.

[0024] The electronic control unit 6, in detail, includes memory, a microprocessor, and input / output interfaces for receiving data from or emitting data to attract the attention of other devices in the vehicle 1. The memory of the electronic control unit is a medium for recording data, on which a computer program containing program code instructions for implementing a method according to one embodiment of the present invention is recorded. The microprocessor can execute this method. In detail, the electronic control unit 6 can send control commands to the steering device 4 via the input / output interfaces of the electronic control unit 6 to apply torque for orienting the steering wheels 2f. Thus, the vehicle 1 is an autonomous or semi-autonomous vehicle, i.e., the vehicle 1 can perform and maintain steering tracking without driver intervention. The vehicle 1 can also be controlled conventionally by a driver by driving the steering wheel. Note in this document that “torque” applied to the steering wheels relates to useful torque for orienting the steering wheels and, consequently, for guiding the vehicle. Thus, this term does not refer to engine torque useful for rotating the wheels and propelling the vehicle.

[0025] Figure 2 shows a vehicle 1 traveling on a driving lane 10. The driving lane is intended to accommodate one vehicle across its entire width. The driving lane 10 is defined on the left and right by two edges BG and BD. These edges can be materialized in the form of boundary lines, such as continuous or dashed lines in white or yellow. In a modified embodiment, edges BG and BD may simply correspond to the lateral ends of the driving lane and can be materialized by a sidewalk, embankment, or simply the edge of the road pavement. The road on which vehicle 1 travels may have multiple driving lanes located to the left and / or right of the driving lane 10.

[0026] Similarly, Figure 2 shows virtual lines LS1G, LS2G, LS3G, LS1D, LS2D, LS3D, and LM. These lines are not materialized on the driving lane, but are briefly shown to clearly understand the present invention. Lines LS1G, LS2G, and LS3G are substantially parallel to the left edge BG and are located at thresholds S1, S2, and S3, respectively, from edge BG. Similarly, lines LS1D, LS2D, and LS3D are substantially parallel to the right edge BD and are located at thresholds S1, S2, and S3, respectively, from edge BD. Line LM extends at equidistant from edge BG and edge BD. In other words, line LM is the center line of the driving lane 10. Note that the driving lane shown in Figure 2 is straight. However, the present invention can be realized even if the driving lane is curved or bent.

[0027] The detection means 8 can identify the edges BG and BD of the driving lane 10 and determine the lateral position of the vehicle 1 on the driving lane. The lateral position of the vehicle can be determined, for example, by quantifying the lateral distance D (i.e., lateral deviation D) separating the left edge of the vehicle from the left edge BG of the driving lane.

[0028] In this document, the vertical axis is defined as the axis of the driving lane at the height of vehicle 1. Therefore, the vertical axis may be substantially parallel to the edges BG and BD. Assuming that the edges BG and BD are probably not strictly parallel, the vertical axis may represent the bisector of these two lines at the height of vehicle 1. The vertical axis may also correspond to an axis parallel to only one of the two edges BG or BD. The horizontal axis is the axis of the driving lane perpendicular to the vertical axis. The adjective "lateral" describes the object that follows the horizontal axis. Therefore, the lateral position of the vehicle indicates the position of the vehicle following the horizontal axis.

[0029] Below, an embodiment of a method for controlling the lateral position of vehicle 1 on the driving lane 10 will be described with reference to Figure 3.

[0030] In the first step E1, automatic control of the vehicle's position is performed to follow the first reference track TR1. The first reference track can be defined as substantially the center of the driving lane. Thus, the first reference track can correspond to the center line LM. In other words, the vehicle's lateral position is controlled to follow the center line LM.

[0031] Automatic control of the lateral position of a vehicle following a reference track TR1 can be performed by a closed-loop algorithm schematically shown in Figure 4. Thus, the first control step E1 includes a substep E11 for calculating the vehicle's reference state vector Xref, a substep E12 for calculating the vehicle's observed state vector Xobs, and a substep E13 for calculating a setpoint for the steering angle δc of the vehicle's steering wheels based on the difference between the reference state vector Xref and the observed state vector Xobs. Next, the observed state vector Xobs is calculated using the setpoint for the steering angle δc during subsequent iterations of the first step E1.

[0032] The reference state vector Xref describes the desired position and trajectory for the vehicle. This state vector can be calculated in detail based on a first reference trajectory TR1, i.e., the center line LM. When vehicle 1 encounters various obstacles caused by internal or external factors of vehicle 1, the reference state vector Xref at a given instant may differ from the observed state vector Xobs of the vehicle. These internal or external factors may be, for example, changes in the vehicle's grip, changes in load, deformation of the roadway, wind impact, or the accuracy of the detection means 8.

[0033] The observed state vector Xobs can be calculated from sensors installed on the vehicle, specifically from the detection means 8, the vehicle's motion model (identified by 11 in Figure 4), and the observer (identified by 12 in Figure 4). The observed state vector Xobs may include all or some of the following seven components: - Vehicle sway speed, and / or - The vehicle's angle of head, and / or - The lateral speed of the vehicle, and / or - Lateral deviation of the vehicle from the reference track, and / or - Steering speed of the vehicle's steering wheels, and / or - The steering angle of the vehicle's steering wheels, and / or - The integral of the lateral deviation of the vehicle from the reference track.

[0034] The first control step E1 then includes a substep E14 during which a first torque C1 is calculated. This first torque C1 is calculated by the PID controller 13, i.e., a proportional-integral-derivative controller, based on the steering angle setpoint δc which has already been calculated.

[0035] The first control step E1 also includes a substep E15 during which a gain K1 between 0 and 1 is calculated. Favorably, the gain K1 may be a decreasing function of the torque applied to the steering wheel 5 by the driver. In other words, the greater the torque applied to the steering wheel 5 by the driver, the smaller the gain K1 will be.

[0036] Finally, the first control step E1 includes a substep E16 in which the torque C2 applied to the steering wheel 2f is calculated by multiplying the torque C1 by a gain K1. The torque C2 thus obtained can then be applied to the steering device 4 in order to orient the steering wheel.

[0037] Therefore, vehicle 1 can be controlled according to several operating modes. In the first mode, called manual mode, which corresponds to a gain K1 value equal to 0, the orientation of the steering wheels 2f is controlled solely by the driver. In the second mode, which corresponds to a gain K1 value equal to 1, the torque C2 transmitted to the steering wheels is sufficient to follow a first reference trajectory. Finally, in the third operating mode, where the gain K1 is between 0 and 1, the torque C2 transmitted to the steering wheels is insufficient to follow the first reference trajectory. However, this torque C2 is perceived by the driver by gripping the steering wheel and is interpreted as a prompt to orient the steering wheel to follow the first reference trajectory TR1. In this case, the steering torque actually applied to the steering wheels 2f is the sum of the torque C2 and the torque transmitted to the steering wheels by the driver's action on the steering wheel. Control of the vehicle's lateral position is considered automatic as long as the gain K1 is strictly greater than 0.

[0038] In parallel with the first control step E1, the method includes a first step E2 of monitoring the lateral distance separating the vehicle from the edges BG and BD of the driving lane.

[0039] The first monitoring step E2 includes a substep E21 which first calculates a first threshold S1. In detail, the first threshold S1 can be calculated based on the width of the driving lane 10 and the lateral speed of the vehicle 1 on the driving lane 10. The first threshold can be determined to comply with standards that impose a driver warning if the vehicle drifts. The width of the driving lane may be the height of the vehicle 1, or the distance separating the edges BG and BD of the driving lane at a given distance in front of the vehicle 1. The width of the driving lane can be calculated by the detection means 8. The lateral speed of the vehicle 1 represents the speed of the vehicle following the lateral axis Y, i.e., the speed at which the vehicle is approaching the edge BG or edge BD. Figure 6 shows an example of mapping the first threshold S1. Axis X1 represents a lane width between, for example, 2.5m and 4m. Axis Y1 represents the lateral speed of the vehicle 1 in the form of an absolute value between, for example, 0m / s and 1.8m / s. Axis Z1 represents the obtained threshold S1, which may be, for example, between approximately 10 cm and 30 cm. The threshold S1 may be an increasing function of lateral velocity and an increasing function of lane width. It is advantageous for the threshold S1 to be exactly the same on both sides of the driving lane, but in modified embodiments, the threshold S1 may be different on both sides of the driving lane.

[0040] The first monitoring step E2 includes a substep E22 that warns the driver if the lateral distance separating the vehicle from the edge BD or edge BG of the driving lane falls below a first threshold S1 that has already been calculated. The driver is warned by activating the warning means 9. Thus the driver is warned that the action of the steering device 4 on the steering wheels 2f is insufficient to follow the first reference trajectory TR1. The driver can then operate the steering wheel 5 to return the vehicle to the center of the driving lane. Thus the legal regulatory requirement to warn the driver when the vehicle is getting too close to the edge of the driving lane is met.

[0041] In the third substep E23, if the lateral distance separating the vehicle from the edge BD or edge BG of the driving lane becomes greater than or equal to the third threshold S3, or again greater than or equal to the third threshold S3, the warning given to the driver is stopped. The third threshold S3 is strictly longer than the first threshold S1. The third threshold S3, which can be called the reset threshold, can be defined based on the width and curvature of the driving lane. Thus, the untimely activation and deactivation of the warning means 9 are avoided.

[0042] While the vehicle's position is controlled to follow a first reference trajectory, the driver may want to offset their vehicle to one side of the lane in anticipation of some form of hazard. For example, if the driver is attempting to overtake a truck on the left, the driver may want to offset their vehicle to the left side of the lane to increase the lateral distance separating the vehicle from the truck. If a motorcycle or emergency vehicle is attempting to overtake on the left, the driver may want to offset their vehicle to the right side to leave a sufficient passage. The driver may also simply want to offset their vehicle in relation to a vehicle traveling ahead in the lane to improve their road view ahead of the vehicle. Therefore, the driver applies a command in the form of torque applied to the steering wheel 5 to guide their vehicle in the desired direction in order to offset their vehicle.

[0043] The control method then includes step E3 of detecting a command applied to the steering wheel 5 by the driver. Next, the lateral deviation of the vehicle from the first reference trajectory and the torque applied to the steering wheel 5 are observed. As will be seen below, the lateral deviation from the reference trajectory serves as the basis for defining a second reference trajectory TR2. Before defining the second reference trajectory TR2, detection step E3 may include substep E31 of verifying various criteria related to the command applied by the driver.

[0044] The verification step E31 may include a substep E311 that compares the vehicle's lateral deviation to a minimum lateral deviation threshold. This minimum threshold, which can be fixed to a value of, for example, 10 cm, can filter out unconscious shifts by the driver relative to the first reference trajectory TR1. Thus, as long as the driver's action on the steering wheel results in a vehicle deviation of less than 10 cm from the reference trajectory, the first control step E1 continues and the vehicle continues to follow the first reference trajectory TR1.

[0045] Verification step E31 may also include a substep E312 which compares the vehicle's lateral deviation to a maximum lateral deviation threshold. This maximum threshold can be defined based on the vehicle's speed, lane width, and vehicle width, based on the vehicle's lateral acceleration. More specifically, this maximum threshold may be an increasing function of the lane width and / or a decreasing function of the vehicle's width, vehicle speed, and lateral acceleration. Defining a maximum threshold prevents excessive offset of the second reference trajectory relative to the center of the lane. Therefore, if a driver's command results in excessive lateral deviation, the command will not result in the delimitation of the second reference trajectory.

[0046] Verification step E31 may also include a substep E313 which compares 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 lane. Thus, this minimum threshold may be between, for example, 0.8 Nm and 1.6 Nm. In a modified embodiment, this minimum torque threshold may be equal to a fixed value, for example, a value defined as 1.5 Nm. This minimum torque threshold allows for the detection of unconscious actions by the driver on the steering wheel. For example, even if the driver temporarily releases the steering wheel from one of their hands, a slight change in the torque transmitted to the steering wheel can be detected without corresponding to the driver's intention to offset their vehicle. However, the first control step E1 continues, and the vehicle continues to follow the first reference trajectory.

[0047] Verification step E31 may also include a substep E314 which compares the torque applied to the vehicle's steering wheel with a maximum torque threshold. This maximum torque threshold can be defined, for example, as 4 Nm. When the driver applies such torque to the steering wheel, this torque may be interpreted as an emergency command, specifically an evasive maneuver, and the control method may then be deactivated, allowing the driver complete control of the vehicle's direction.

[0048] To ensure that the criteria are verified within the shortest possible duration, a time period can be applied to each of the substeps E311, E312, E313, and E314. For example, a low-frequency filter can be used to filter out lateral deviation measurements of the vehicle and / or torque values ​​applied to the steering wheel. A counter can also be used to verify that the condition is observed while the method is repeated a sufficient number of times.

[0049] If all the criteria verified during verification step E31 are met, the lateral deviation separating vehicle 1 from the first reference trajectory can be stored and used as the lateral offset OL to define the second reference trajectory TR2. Thus, the second reference trajectory TR2 is substantially parallel to the first reference trajectory TR1 and offset from the first reference trajectory TR1 by the value of the lateral offset OL. Therefore, detection step E3 can include a substep E32 for determining the lateral offset OL. This determination step E32 can include the detection of an increase following the stabilization of the torque applied to the steering wheel by the driver. In this case, the lateral offset corresponds to the lateral deviation obtained after the torque applied to the steering wheel has stabilized. The torque can be considered stable from the moment it falls below a threshold value defined by parameterization, for example, a value of about 0.7 Nm. If the torque is not stable at the end of a duration fixed by parameterization, for example, a duration of about 10 seconds, it can also be provided to deactivate the control method. In the modified configuration, the lateral offset can also be determined by observing the subsequent increase in the stabilization of another state parameter of the vehicle. This state parameter may be, for example, a first reference track TR1, the vehicle's heading angle, or the lateral deviation with respect to the vehicle's lateral velocity.

[0050] Finally, the lateral offset OL is defined by the driver's actions on the steering wheel. Therefore, the lateral offset OL is a matter of driver choice, not automatic definition. Thus, drivers can freely define the lateral offset value of their vehicle based on their own requirements and traffic conditions.

[0051] Next, in the second control step E4, the vehicle's position is automatically controlled to follow the second reference track TR2. Naturally, this step is realized only if the criteria tested during the verification step E31 are met, and only if the criteria are met.

[0052] Controlling the lateral position of a vehicle following the second reference track TR2 can be carried out in exactly the same way as controlling the lateral position of a vehicle following the first reference track TR1. Therefore, the second control step E4 can include substeps E41, E42, E43, E44, E45, and E46, which are exactly the same as steps E11, E12, E13, E14, E15, and E16 described above, except that the first reference track TR1 is replaced by the second reference track TR2. Thus, the driver can follow the second reference track TR2 without having to apply torque to the steering wheel against the torque generated by the steering device 4, which tends to return the vehicle toward the first reference track TR1. Therefore, the guidance of the vehicle 1 is more pleasant and more precise.

[0053] In parallel with the second control step E4, the method includes a second step E5 in which the lateral distance separating the vehicle from the edge BG and edge BD of the driving lane is monitored. The second monitoring step E5 is also carried out in the same manner as the first monitoring step E2. Thus, the second monitoring step E5 includes substeps E51, E52 and E53 corresponding to the substeps E21, E22 and E23 described above. However, the second monitoring step E5 is distinguished from the first monitoring step E1 in that the first threshold S1 is replaced by a second threshold S2 which is strictly smaller than the first threshold S1. In other words, during the second control step E4, the vehicle may approach the edge BG or edge BD before a driver warning is triggered. This avoids the triggering of an inappropriate driver warning because the vehicle's offsetting behavior is intentional. However, if the vehicle approaches the lateral edge BG, BD too closely, the warning means are maintained. The warning given to the driver during step E52 may be exactly the same as the warning given to the driver during step E22. In a modified version, this warning may be different, for example, more intense in consideration of proximity to the edge BG or edge BD of the driving lane.

[0054] The first monitoring step E2 is stopped immediately when the second monitoring step E5 is activated. This transition between the two monitoring steps may occur if the criteria tested during verification step E31 are met. Thus, at any given time, there is at least one threshold S1 or S2, and the driver is warned if that threshold is exceeded.

[0055] Figure 7 shows an example of mapping the second threshold S2. Axis X1 represents the lane width, for example, between 2.5m and 4m. Axis Y1 represents the lateral speed at which vehicle 1 approaches the edge, for example, between 0m / s and 1.8m / s. Axis Z1 represents the obtained threshold S2, which may be, for example, between approximately 0cm and 20cm. Threshold S2 may be an increasing function of lateral speed and an increasing function of lane width. It is advantageous for threshold S2 to be exactly the same on both sides of the driving lane, but in modified forms, threshold S2 may be different. Note that threshold S2 is independent of the lateral offset OL.

[0056] In addition to a warning given to the driver when threshold S1 or threshold S2 is exceeded, the system can provide a step to automatically return the vehicle to the center and re-establish a lateral distance from edge BG or edge BD that is strictly longer than threshold S1 or threshold S2, respectively.

[0057] Figure 5 illustrates a method for warning the driver if the vehicle drifts laterally. State P1 corresponds to the state in which the method for controlling the vehicle's lateral position is active. From state P1, a first test V1 is performed to determine whether the vehicle has reached a first threshold S1, in other words, whether one edge of the vehicle has reached either line LS1G or LS1D. If the lateral distance separating the vehicle from edge BD or edge BG remains strictly longer than threshold S1, the vehicle remains in state P2 and no warning is issued. On the other hand, if the lateral distance becomes less than or equal to threshold S1, a second test V2 is performed to determine whether torque is being applied to the vehicle's steering wheel 5. If torque is being applied to the vehicle's steering wheel 5, the vehicle remains in state P2 and no warning is issued. In contrast, if no torque is being applied to the vehicle's steering wheel 5, the vehicle progresses to state P3 and a driver warning is triggered. From state P2, a third test V3 is performed to determine whether the vehicle has reached a second threshold S2, in other words, whether one edge of the vehicle has reached either line LS2G or LS2D. If the lateral distance separating the vehicle from edge BD or edge BG remains strictly longer than threshold S2, the vehicle remains in state P2 and no warning is issued. On the other hand, if this lateral distance falls below threshold S2, the vehicle progresses to state P3 and a driver warning is triggered.

[0058] In other words, the driver is only warned when threshold S1 is reached if no torque is being applied to the steering wheel. The driver is always warned when threshold S2 is reached.

[0059] From state P3, a fourth test V4 is performed, which is to determine whether the vehicle has reached a third threshold S3, in other words, whether the vehicle has returned to the space defined between lines LS3G or LS3D. The driver warning is maintained unless the vehicle has returned to the space defined between lines LS3G or LS3D. If the vehicle has returned to the space defined between lines LS3G or LS3D, the driver warning is deactivated.

[0060] According to an original aspect of the present invention, the second control step E4 includes a transition step E40 performed at the start of the second control step E4. The objective of the transition step E40 is to provide a smooth transition between two reference trajectories TR1 and TR2 without overshoot and without jerky movements. The transition step E40 includes replacing the components of the observed state vector Xobs of the vehicle with components calculated 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 moment the transition step E40 is performed. More specifically, the components of the state vector corresponding to the integral of the vehicle's lateral deviation from the reference trajectory can be replaced with values ​​calculated such that the steering angle setpoint δc of the vehicle's steering wheels is equal to the current value of the steering angle δm.

[0061] The present invention allows the driver to offset their vehicle within the driving lane without effort and without the positioning warning being triggered in an inappropriate time.

[0062] According to another specific feature of the present invention, the control method includes a step of temporarily maintaining a second control step E4, and then a third step E6 of automatically controlling the position of the vehicle following a first reference track TR1. The second control step R4 can be maintained for a duration predetermined by calibration. This duration may correspond to the average duration of an overtaking maneuver, for example, an average duration of about 10 seconds at the shortest. In a modified embodiment, a return to the first reference track can be automatically triggered following the detection of the end of the overtaking maneuver. Thus, at the end of this predetermined duration, the vehicle can automatically resume driving at the center position of the driving lane and follow the first reference track. Advantageously, a transition step similar to the transition step E40 described above can be provided to change the reference track without jerking.

[0063] During control, the lateral position of the vehicle may cause fluctuations in the reference track being followed. These fluctuations, which can be around 10 cm, can be due to various internal or external factors of the vehicle, as mentioned above. A safety margin can be defined as a parameterized function of the vehicle's speed. Advantageously, the second reference track TR2 is defined taking this safety margin into consideration. Thus, the second reference track can be defined at a distance of at least the safety margin from line LS2G or LS2D.

Claims

1. A control method for controlling the lateral position of a vehicle (1) on a driving lane (10), A first control step (E1) that automatically controls the lateral position of the vehicle following a first reference track (TR1), A first monitoring step (E2) for monitoring the lateral distance separating the vehicle from the edge of the driving lane (BD, BG), wherein the first monitoring step includes a substep (E22) for warning the driver when the lateral distance separating the vehicle from the edge of the driving lane falls below a first threshold (S1), and then, Step (E3) detects a command applied by the driver to the steering wheel (5) of the vehicle to shift the vehicle toward the edge of the lane, and then, A step of stopping the first monitoring step (E2), A second control step (E4) for automatically controlling the lateral position of the vehicle following a second reference track (TR2), wherein the second reference track (TR2) is determined based on the command applied to the steering wheel by the driver, A second monitoring step (E5) for monitoring the lateral distance separating the vehicle from the edge of the driving lane, wherein the second monitoring step includes a substep (E52) for warning the driver when the lateral distance separating the vehicle from the edge of the driving lane is less than or equal to a second threshold (S2), and the second monitoring step (E5) for monitoring the lateral distance is such that the second threshold (S2) is strictly shorter than the first threshold (S1). Includes, The control method described above is A substep (E21) of calculating the first threshold (S1) based on the width of the lane and the lateral speed of the vehicle on the lane, and / or A method characterized by including a substep (E51) of calculating the second threshold (S2) based on the width of the driving lane and the lateral speed of the vehicle on the driving lane.

2. The control method according to claim 1, wherein the control method includes a substep (E23, E53) of stopping the warning given to the driver when the lateral distance separating the vehicle from the edge of the driving lane becomes greater than or equal to a third threshold (S3), and the third threshold (S3) is strictly longer than the first threshold (S1).

3. The first control step (E1) and / or the second control step (E4) A substep (E14, E44) for calculating the first steering torque (C1) of the steering wheel (2f) of the vehicle, A substep (E15, E45) for calculating the gain (K1), which is a reduction function of the torque applied to the steering wheel by the driver, Substeps (E16, E46) include calculating the second steering torque (C2) of the steering wheel of the vehicle by multiplying the first steering torque (C1) by the gain (K1), and The control method according to claim 1 or 2, characterized by including the following:

4. The control method includes a step (E31) of verifying at least one criterion related to the command, and the step of automatically controlling the position of the vehicle following the second reference track (TR2) is performed only if the at least one criterion is met and the at least one criterion is met, and the step of verifying at least one criterion is performed A substep (E311) of comparing the lateral deviation of the vehicle from the first reference track (TR1) with a minimum lateral deviation threshold, and / or A substep (E312) of comparing the lateral deviation of the vehicle relative to the first reference track (TR1) with a maximum lateral deviation threshold, and / or A substep (E313) of comparing the torque applied to the steering wheel of the vehicle with a minimum torque threshold, and / or Substep (E314) comparing the torque applied to the steering wheel of the vehicle with a maximum torque threshold. A control method according to any one of claims 1 to 3, characterized by including the following:

5. The control method according to any one of claims 1 to 4, wherein the control method includes a determination step (E32) that determines the lateral offset (OL) of the vehicle with respect to the first reference trajectory (TR1), following the command applied to the steering wheel by the driver, the second reference trajectory (TR2) being defined based on the first reference trajectory (TR1) and the lateral offset (OL), and the determination step includes detecting an increase in torque applied to the steering wheel by the driver, followed by detection of stabilization thereafter, and / or detection of an increase in the vehicle state parameter, followed by detection of stabilization thereafter.

6. The second control step (E4) is, The steps include: (E41) calculating the reference state vector (Xref) of the vehicle (1), The steps include: (E42) calculating the observed state vector (Xobs) of the vehicle (1); Step (E43) of calculating the setting point for the steering angle (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) performed at the start of the second control step (E4), wherein the transition step includes replacing a component of the observed state vector (Xobs) of the vehicle with a component calculated such that the steering angle setting point (δc) of the steering wheel (2f) of the vehicle is equal to the current value of the steering angle (δm) of the steering wheel. The control method according to claim 3, or claim 4 or 5, which directly or indirectly references claim 3.

7. The control method described above is A step of temporarily maintaining the second control step (E4), and then automatically A third step (E7) is to automatically control the position of the vehicle following the first reference track (TR1), and A control method according to any one of claims 1 to 6, characterized by including the following:

8. A computer program product comprising program code instructions recorded on a computer-readable medium, wherein when the program is executed on a computer, the computer program product performs a step of the control method described in any one of claims 1 to 7.

9. An automatic vehicle (1) comprising a steering wheel (2f) connected to a steering wheel (5), means (8) for detecting the environment of the vehicle, means (9) for warning the driver of the vehicle, and at least one computer (6) configured to perform the control method described in any one of claims 1 to 7.

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