Method for Controlling Lateral Position of Motor Vehicle

Abstract

The invention relates to a method for controlling the lateral position of a motor vehicle (1), characterized in that it comprises: a step (E41) of calculating a visibility distance (L) of a detection means (8) installed in the vehicle (1); a step (E5) of calculating a first component (FFD) of a steering angle setpoint (δc) of the steered wheels (2f) of the vehicle (1), the first component (FFD) being an open-loop component of the control system, the first component (FFD) being weighted by a gain (G), the gain (G) being a decreasing function of the visibility distance (L); and a step (E6) of calculating a second component (FBK) of the steering angle setpoint (δc), the second component (FBK) being a closed-loop component of the control system.

Description

Technical Field

[0001] The present invention relates to a method for controlling the lateral position of a motor vehicle, particularly of a vehicle equipped with a driver assistance system. The present invention further relates to a motor vehicle comprising hardware and / or software means for carrying out such a method. Finally, the present invention relates to a method for calibrating such a vehicle.

Background Art

[0002] A vehicle equipped with a driver assistance system generally includes a computer-controlled steering system. The steering system controls the orientation of the steered wheels of the vehicle so that the vehicle follows a given trajectory. The computer executes a control method that enables the vehicle to be positioned laterally on a traffic lane. In particular, the computer can execute a control method called LCA (Lane Centering Assist) that enables the vehicle to be kept at the center of its traffic lane.

[0003] Such control methods require that the vehicle be steered gradually and without jerks along a given trajectory. However, it has been found that the quality of control implemented by vehicles known from current technology is degraded when the vehicle's state and / or external conditions change. In particular, the vehicle's load, the position of its center of gravity, the condition of its tires, or the type of tires used, affects the vehicle's dynamic behavior, especially when turning. The steering angle setpoint calculated based on the execution of the control method may lead to a trajectory that differs significantly from the planned trajectory. Corrective movements to alter the vehicle's lateral position then occur. These corrective movements can be delayed, even inappropriate, and can cause discomfort to the driver. Therefore, performance degradation can be felt not only when the vehicle's state changes, but also when external conditions change, such as changes in road grip and / or changes in wind force or direction.

[0004] Methods are known for calculating the steering angle setpoint of the steering wheel, relying on the use of vehicle state sensors to adapt control laws. However, identifying factors that disrupt the vehicle's dynamic behavior remains complex and difficult. Furthermore, such sensors are complex to integrate into a vehicle. These methods are therefore complex to implement and do not allow for complete overcoming of the lateral acceleration experienced by the vehicle.

[0005] Overview of the invention The objective of the present invention is to provide a method for controlling the lateral position of a motor vehicle that corrects the above-mentioned drawbacks and improves upon control methods known from the prior art.

[0006] More specifically, the first subject of the present invention is a method for controlling the lateral position of a motor vehicle, which is less dependent on the state of the vehicle or on external conditions of the vehicle.

[0007] A second subject of the present invention is a method for controlling the lateral position of a motor vehicle that is not only less dependent on the state of the vehicle and / or the external conditions of the vehicle, but also does not require the use of a vehicle state sensor, or a sensor for external conditions of the vehicle, or even the identification of factors that alter the dynamic behavior of the vehicle. [Overview of the Initiative]

[0008] The present invention is a method for controlling the lateral position of a motor vehicle, - A step of calculating the distance of attention (distance de visee) of the detection means installed inside the vehicle, - A step of calculating a first component of the steering angle setpoint of a steering wheel of a vehicle, wherein the first component is an open-loop component of a control system, the first component is weighted by a gain, and the gain is a decreasing function of the distance of interest, - A step of calculating a second component of the steering angle setpoint, wherein the second component is a closed-loop component of the control system. This includes methods.

[0009] The aforementioned gain may be between 0 and 1.

[0010] The gain may be a decreasing linear function of the distance of interest, and / or may be equal to 1 when the distance of interest is 0.

[0011] The control method may include the step of calculating a steering angle setpoint, wherein the steering angle setpoint is equal to the sum of the open-loop components and the closed-loop components.

[0012] The step of calculating the second component may include a substep of calculating the vehicle state vector, wherein the state vector includes a component equal to the lateral displacement of the vehicle with respect to the reference trajectory at the distance of interest.

[0013] The step of calculating the second component of the steering angle setpoint may include a substep of multiplying the lateral displacement of the vehicle at the distance of interest by the distance of interest.

[0014] The control method is, - A step to calculate the vehicle's future lateral acceleration, - A step of comparing the lateral acceleration with a threshold, and then, - A step of calculating a first component of the steering angle setpoint when the lateral acceleration is greater than or equal to a threshold, wherein the first component is weighted by a gain equal to a predetermined value independent of the distance of interest, - A step of calculating a first component of the steering angle setpoint when the lateral acceleration is strictly below a threshold, wherein the first component is weighted by a gain, and the gain is a decreasing function of the distance of interest. It can include...

[0015] The step of calculating the vehicle's future lateral acceleration may include a substep of obtaining the curvature of the traffic lane using a navigation system.

[0016] The step of calculating the distance of interest may include selecting the minimum value between a predetermined distance and the line of sight (portee de vue) of the vehicle detection means.

[0017] The present invention further relates to a computer program product comprising program code instructions stored on a medium and readable by an electronic control unit for executing steps of a control method as defined above when the program is executed on the electronic control unit.

[0018] The present invention further relates to a computer program product downloadable from a communication network and / or stored on a computer-readable data medium and / or executable by a computer, the product comprising instructions for causing the computer to execute a control method as defined above when the program is run by the computer.

[0019] The present invention further relates to a data storage medium readable by an electronic control unit on which is stored a computer program comprising program code instructions for implementing a control method as defined above.

[0020] The present invention further relates to a computer-readable storage medium comprising instructions for causing a computer to execute a control method as defined above when the instructions are executed by the computer.

[0021] The present invention further relates to a signal from a data medium carrying a computer program product as defined above.

[0022] The present invention further relates to a steering system comprising hardware and / or software means for executing a control method as defined above.

[0023] The present invention further relates to a motor vehicle comprising a steering system as defined above.

[0024] The present invention further relates to a method for calibrating a vehicle as defined above, the calibration method comprising - A first step of measuring a reference lateral deviation of the vehicle with respect to a reference trajectory when the vehicle travels on a first course, the first step of measuring the reference lateral deviation of the vehicle, wherein the attention distance is defined to be equal to zero; - A second step of gradually increasing the attention distance and reducing the gain while the lateral deviation of the vehicle with respect to the reference trajectory is substantially equal to the reference lateral deviation when the vehicle travels on the first course; and and / or, the calibration method comprises: - A first step of defining the attention distance to be equal to a predetermined distance; - A second step of gradually increasing the gain while the lateral deviation of the vehicle with respect to the reference trajectory is below a threshold value when the vehicle travels on a second course. relates to a method.

[0025] These objectives, features, and advantages of the present invention will be explained in detail in the subsequent description of individual embodiments given non - limitatively in relation to the accompanying drawings. [[ID=第十九]]

Brief Description of the Drawings

[0026] [Figure 1] It is a schematic diagram of a motor vehicle according to an embodiment of the present invention. [Figure 2] It is a first top - view schematic diagram of a vehicle on a traffic lane. [Figure 3] It is a second top - view schematic diagram of a vehicle on a traffic lane. [Figure 4] It is a block diagram of a control method according to an embodiment of the present invention. [Figure 5] It is a schematic diagram of a regulator executed in the control method. [[ID=第二十]]<000010> [Figure 6] It is a graph exemplifying the trend of the open - loop gain of the regulator as a function of the attention distance.

Modes for Carrying Out the Invention

[0028] The electronic control unit 6 is electrically connected to the steering wheel angle sensor 7, the steering device 4, and possibly other sensors in the vehicle, and / or other electronic control units or computers in the vehicle 1. The electronic control unit 6 includes, among other things, memory, a microprocessor, and input / output interfaces for receiving data from or sending data to other devices in the vehicle 1. The memory of the electronic control unit is a data storage medium in which a computer program is stored, which includes program code instructions for performing the method according to embodiments of the present invention. The microprocessor is capable of performing this method. Among other things, the electronic control unit 6 is capable of sending control commands to the steering device 4 via its input / output interfaces to turn the steering wheel according to a calculated angle, i.e., to determine the orientation of the steering wheel. The longitudinal axis X1 of the vehicle may be defined as the axis parallel to the direction in which the vehicle is oriented along a straight line.

[0029] Vehicle 1 further includes means 8 for detecting the surroundings of Vehicle 1, such as radar and / or lidar and / or cameras. These detection means may be elements of the steering system. The detection means 8 is further connected to an electronic control unit 6. Vehicle 1 is a vehicle equipped with a driver assistance system.

[0030] Vehicle 1, and lastly, includes a navigation system 9. The navigation system includes, among other things, a database of roads that the vehicle can follow. The navigation system has the ability to calculate the curvature of the road the vehicle is traveling on or is about to travel on. The navigation system is connected to an electronic control unit 6, and this curvature value can be transmitted to the electronic control unit 6.

[0031] Figure 2 illustrates a vehicle 1 traveling on a traffic lane 10. The traffic lane 10 is defined on the left and right by two boundary lines 11, which are embodied on the traffic lane, for example, in the form of continuous or discontinuous lines colored white or yellow. Detection means 8 are capable of identifying the boundary lines 11. The electronic control unit includes software means that enable the calculation of a reference track 12 or setpoint track. The reference track 12 is identified by discontinuous lines in Figure 2. The reference track 12 is a theoretical line that is not visible on the traffic lane 10. The reference track 12 may, for example, embody the center of the lane and correspond to a line that is, for example, equidistant from the two boundary lines 11. In a variation, the reference track 12 may be defined differently. The reference track 12 may be more skewed to one or the other of the two boundary lines 11. The reference track 12 can further be calculated as a correlative element for detecting obstacles or other vehicles present on a traffic lane or on a traffic lane adjacent to traffic lane 10.

[0032] In this document, the longitudinal axis X is defined as the axis of a traffic lane parallel to the reference track at the height of vehicle 1, for example, at the height of the center of gravity of vehicle 1. The transverse axis Y is the axis of a traffic lane perpendicular to the reference track at the height of vehicle 1. Axis Z is explicitly defined as being perpendicular to the longitudinal axis X and the transverse axis Y. The traffic lane illustrated in Figure 2 is a traffic lane that curves to the left. However, the present invention can be equally implemented when the traffic lane is a straight line or curves to the right.

[0033] The state of a vehicle, namely its position on the traffic lane 10 and its trajectory, can be characterized by a set of physical quantities or state variables, partially represented in Figure 2. In particular, the state of the vehicle is characterized by the following quantities: - Vehicle yaw velocity dΨ / dt, and / or, - The vehicle's heading angle Ψ, and / or, - The lateral speed of the vehicle dy / dt, and / or, - The lateral displacement y of the vehicle relative to the reference track, and / or, - The turning speed dδ / dt of the steering wheel of the vehicle, and / or, - The steering angle δ of the steering wheel of the vehicle, and / or, - The integral of the lateral displacement of the vehicle relative to the reference track ly It can be characterized by the following.

[0034] The yaw velocity dΨ / dt is the speed of the vehicle's rotation around axis Z. The yaw velocity can be measured, for example, by means of a yaw sensor. The head angle Ψ can be defined as the angle formed between the longitudinal axis X of the traffic lane 10, i.e., the axis tangential to the reference track 12 at vehicle height, and the longitudinal axis X1 of the vehicle. The lateral displacement y can be defined as the distance from the reference track 12 to a given point on the vehicle (in particular, the vehicle's center of gravity C). In a variation, the lateral displacement y can also be a measure of the distance from the boundary line 11 to a given point on the vehicle. The head angle Ψ and the lateral displacement y can be calculated, for example, using the vehicle detection means 8. The lateral velocity dy / dt is the derivative of the lateral displacement y with respect to time. The integral ly of the lateral displacement can be calculated with respect to time and from an initial time point corresponding to the time of activation of the control method.

[0035] The steering angle δ of a steered wheel can be defined as the angle formed between an axis X2 parallel to the direction of rotation of the steered front wheel and the longitudinal axis X1 of the vehicle. The steering angle δ is proportional to the steering wheel angle measured by the steering wheel angle sensor 7. It should be noted that when the vehicle is moving, the two steered wheels of the vehicle are generally turned by slightly different angles to account for the different radii of curvature followed by each of the steered wheels. These differences can then be considered negligible. Thus, the state of the vehicle can be simplified by using the so-called "bicycle" model, that is, by considering a single steered wheel, for which the steering angle causes the vehicle to follow the same curvature as the two steered wheels would follow with different steering angles. The steering angle of a steered wheel using the "bicycle" model can be, for example, the average angle between the steering angle of the left steered wheel and the steering angle of the right steered wheel. The steering wheel's turning speed dδ / dt is the derivative of the steering angle δ with respect to time.

[0036] The attention distance L may be defined as the minimum value between a predetermined distance Lmax and the field of view Lrange of the vehicle detection means. The field of view of the detection means is the maximum distance at which the detection means can detect the surroundings with a good level of confidence or with sufficient clarity. The field of view depends, in particular, on the sensitivity of the sensor embedded in the detection means, but also on brightness conditions and / or weather or atmospheric conditions. The field of view also depends on the type of traffic lane being followed and the possible presence of obstacles or other vehicles in front of the detection means 8. In particular, when the vehicle begins to turn, the field of view of the detection means 8 may be reduced. The predetermined distance Lmax may be a value determined by the vehicle calibration. The predetermined distance Lmax may be defined, for example, with a value of 30 meters.

[0037] The distance of interest L is represented in particular in Figure 3. Figuratively speaking, the distance of interest can be considered a "fishing rod" attached to the roof of the vehicle. The lateral displacement yL at the distance of interest can be defined as the lateral distance separating the reference track 12 from the end of the "fishing rod". In other words, the lateral displacement yL corresponds to the lateral displacement between the reference track 12 and a predetermined point at the distance of interest L in front of the vehicle 1, in a direction perpendicular to the tangent to the reference track at vehicle level.

[0038] The lateral displacement yL is measured in polynomial form, particularly at the vehicle's center of gravity C, by a camera that provides real-time lateral displacement data, which makes it possible to know the lateral displacement at any distance (within the limits of the camera's field of view), and especially at distance L.

[0039] Referring to Figure 4, a method for controlling the lateral position of vehicle 1 will now be described according to one embodiment of the present invention. The method can be subdivided into seven steps: E1 to E7. This driver assistance method can be repeated according to a given frequency. As will be described in detail below herein, the control method further relies on a control system called a regulator. The control system includes a first open-loop component FFD (also called "feedforward") and a second closed-loop component FBK (also called "feedback"). The FFD loop is inherently reactive, while the FBK loop is slower, which improves comfort and allows for correction of errors in the open-loop model. The steering angle setpoint of the steering wheel is obtained by the sum of the first component FFD and the second component FBK. The present invention makes it possible to mitigate the FFD components during turns and simultaneously compensate for this by adapting the FBK components, thereby transforming the turning process into a more solid manner and improving the driver's perception, the driver thus benefiting from greater comfort.

[0040] In the first step E1, a reference track 12 is calculated. The reference track is the track that the vehicle will follow. For this final purpose, for example, boundary lines 11 can be detected by the detection means 8, and then the reference track 12 can be calculated as a line placed equidistant from the two boundary lines 11. The reference track can be represented by a reference state vector Xref, which is used as input to the control system. The reference state vector Xref is therefore calculated as a function of the reference track 12.

[0041] In the second step E2, the future lateral acceleration of the vehicle, i.e., the lateral acceleration that the vehicle will withstand after a time T0 which may be defined, for example, by calibration, is calculated. For this ultimate purpose, the curvature of the traffic lane 10 in front of the vehicle may first be determined, and this value may be combined with the vehicle's speed and possibly its acceleration to estimate the lateral acceleration as the vehicle is moving based on that curvature. For example, the lateral acceleration aymax of the vehicle may be calculated by the following formula. ay max =ρ(Lmax).v 2 In that formula, - p(Lmax) specifies the curvature of the traffic lane at a distance Lmax from the vehicle. -v indicates the vehicle's speed.

[0042] The curvature of a traffic lane can also be calculated at a fixed distance from the vehicle. This curvature is determined using the detection means if they have a sufficient field of view, otherwise it can be obtained using the in-vehicle navigation system 9. Assuming the latter, the curvature of the traffic lane can be transmitted from the navigation system to the electronic control unit. The use of data from the navigation system makes it possible to calculate the curvature of the traffic lane even when the detection means have an insufficient field of view.

[0043] In the third step E3, the lateral acceleration is compared to a threshold S1. This threshold S1 may be equal to, for example, 0.2g or 0.25g, but as a variation, the threshold S1 may be defined with different values ​​selected after testing of the vehicle. This comparison makes it possible to distinguish normal driving conditions, in which turns are not very sharp and lateral acceleration is low, from driving conditions, in which turns are sharper and the field of view of the detection means is reduced.

[0044] In the fourth step E4, a gain G is calculated, which is useful for calculating the open-loop components in order to weight the contribution of the open-loop component FFD. Two cases can be distinguished, depending on whether the lateral acceleration is greater than or equal to the threshold S1, or strictly less than the threshold S1.

[0045] In the case where the lateral acceleration is strictly below the threshold S1, the gain G is defined as a decreasing function of the distance of interest L. In other words, the larger the distance of interest, the lower the gain G, and the lower the contribution of the open-loop component FFD in calculating the setpoint angle.

[0046] The gain G can be between 0 and 1. The contribution of the open-loop component is therefore at most equal to the value its contribution would have if the gain G were not included, and when the gain G is strictly less than 1, the contribution of the open-loop component to the calculation of the steering angle setpoint is reduced.

[0047] The gain G can be equal to 1 when the distance of interest is 0. Thus, when the line of sight range of the detection means is 0, the contribution of the open-loop component is not reduced.

[0048] More specifically, and still in the case where the lateral acceleration is strictly below the threshold S1, the fourth step E4 may include a first substep E41 in which the distance L of interest of the detection means installed in the vehicle 1 is calculated. As previously confirmed, the distance L of interest can be calculated by the following formula. L = min(Lmax, Lrange) In that formula, - Lmax specifies a predetermined distance. - Lrange specifies the field of view range of the vehicle detection means.

[0049] Next, in the second substep E42, the gain G can be calculated by means of a function dependent on the distance of interest. The gain G can be calculated, in particular, by the following formula. In the formula, β specifies a parameter that can be adjusted during the vehicle calibration phase. The parameter β is less than or equal to 1 and can be strictly greater than 0. Figure 6 illustrates two functions for calculating the gain G, given by the example. According to the first function F1, the gain G decreases linearly from 1 (when the distance of interest is zero) to 0 (when the distance of interest is equal to a given distance Lmax). The parameter β of the first function F1 is therefore equal to 1. Function F2 represents a second example of calculating the gain G, where the parameter β is strictly less than 1.

[0050] In cases where the lateral acceleration is greater than or equal to a threshold S1, the gain G can be set to a predetermined value γ that does not depend on the distance of interest.

[0051] Next, in the fifth step E5, the open-loop component FFD of the steering angle setpoint is calculated. This open-loop component may be substantially equal to the steering angle δeq of the steering wheel required to follow the curvature of the road, weighted by the gain G calculated in the fourth step E4. Thus, the open-loop component can be calculated by the following formula. FFD=G.δeq

[0052] The steering angle δeq of the steering wheel required to follow the curvature of the road can be calculated using the following formula. In the formula TIFF2022552087000003.tif18170, - ρ indicates the curvature of the traffic lane at vehicle height. -v indicates the vehicle's speed. - a11, a12, a16, a31, a32, and a36 are components of matrix A that will be defined later, and these components are functions of the intrinsic characteristics of vehicle 1 and of the speed of vehicle 1.

[0053] In the sixth step E6, the closed-loop component FBK of the steering angle setpoint is calculated. The closed-loop component allows for correction of the open-loop component that best follows the reference track regardless of the vehicle state and / or external conditions. The closed-loop component is calculated by means of a closed-loop regulator, which is based on a vehicle state representation. The goal of the closed-loop component is to correct all reference state vectors Xref, and in particular the head direction angle Ψ, the derivative of the head direction angle dΨ / dt, and the wheel steering angle δ, so that these parameters match the parameters of the reference state vector Xref.

[0054] Figure 5 shows a control system according to an embodiment of the present invention. The hybrid vector Xhyb is shown in Figure 5 as the output of the observer for the sake of simplicity, but it should be kept in mind that this output is not direct because the hybrid vector Xhyb is selected, and its reconstruction for two observed states is done by recapturing the direct outputs of the observer for these two states and by recapturing the measured values ​​for five other states. Nevertheless, as a variation, the vector Xhyb may not be hybrid, but instead contain only observed states, as shown in Figure 5.

[0055] In the first substep E61 of the sixth step E6, an observed state vector characterizing the position and trajectory of the vehicle on the traffic lane 11 is calculated, and a hybrid state vector Xhyb, encompassing five measurements (dΨ / dt, Ψ, yL, δ, and -ly) and two observed states (dy / dt and dδ / dt), is reconstructed to reconstruct these states dy / dt and dδ / dt, which are not known by measurement. The reference state vector Xref of the vehicle that constitutes the setpoint is independent of the hybrid state vector at a given moment. The hybrid state vector may be defined as follows. TIFF2022552087000004.tif49170

[0056] The hybrid state vector, therefore, contains seven components. Generally, the state vector can characterize the position, velocity, and acceleration experienced by the vehicle at a given moment. The hybrid state vector is therefore a time-variable vector. Of the seven components of the hybrid state vector, the components dΨ / dt, Ψ, dy / dt, dδ / dt, δ, and -ly characterize the position and trajectory of vehicle 1 at the present moment, i.e., the moment during which the control method is performed, or at the actual position of vehicle 1. As previously confirmed, the characteristic yL corresponds to the lateral displacement of a given point at a point of interest at a distance L in front of the vehicle, perpendicular to the tangent to the trajectory at the vehicle level, with respect to the reference trajectory 12. In variations, the components of the state vector may be presented in a different order. The following explanation will then be adapted accordingly.

[0057] The hybrid state vector Xhyb is reconstructed from the observed vector and the measured values, and therefore its hybrid state vector is derived from sensors embedded in the vehicle, from the vehicle's kinematics model (identified by 21 in Figure 5), and from the observer (identified by 22 in Figure 5). The kinematics model 21 can be described by the following equations. dXhyb / dt = A.Xhyb + B1.δc + B2.ρ

[0058] It is a given formula, and in that formula, - dXhyb / dt is the derivative of the hybrid state vector Xhyb with respect to time. - δc is the steering angle setpoint of the steered wheel calculated in a preceding iteration of the control method. - ρ is the curvature of the traffic lane. - A is a 7x7 matrix defined below: - B1 and B2 are vectors with the following seven components:

[0059] Matrix A can be defined by the following formula. In the formula TIFF2022552087000005.tif45170, - cf specifies the drift stiffness of the vehicle's front suspension. - cr indicates the drift stiffness of the vehicle's rear suspension. - lf specifies the distance between the vehicle's center of gravity C and the front suspension. - lr indicates the distance between the vehicle's center of gravity C and the rear suspension. - lz indicates the vehicle's inertia. - m indicates the vehicle's weight. -v indicates the vehicle's speed. - ζ specifies the damping factor of the steering system. - ω explicitly indicates the natural frequency of the steering system filter. - L indicates the distance of focus.

[0060] parameter c f , c r , l f , l r , l zm, ζ, and ω are therefore constants that characterize the vehicle. These parameters are defined once for every instance of vehicle tuning and can be stored in the memory of the electronic control unit.

[0061] By using "aij", the components of row i and column j of matrix A are defined, thereby specifying parameters a11, a12, a16, a31, a32, and a36, which are useful for calculating the steering angle δeq, which is necessarily included in calculating the open-loop component FFD. In particular, the following apply. TIFF2022552087000006.tif86170

[0062] Matrix A is multiplied by the state vector Xhyb. The incorporation of the distance of interest L in matrix A allows for compensation of the reduction of the open-loop component FFD resulting from multiplying the open-loop component FFD by the gain G. Thus, advantageously, the larger the distance of interest, the lower the weight of the open-loop component and the greater the weight of the closed-loop component FBK. In a modified form, the distance of interest L can be incorporated by any other means in calculating the closed-loop component.

[0063] Vector B1 can be defined by the following formula. In that formula, ω explicitly represents the natural frequency of the steering system filter.

[0064] Vector B2 can be defined by the following formula. In the formula TIFF2022552087000008.tif33170, -v indicates the vehicle's speed. - L indicates the distance of focus.

[0065] Furthermore, the measurement vector Y can be defined by the following formula. Y=C.Xhyb In that equation, C explicitly represents a diagonal matrix that allows for the separation of state variables that constitute the hybrid vector Xhyb, which are directly available from sensors embedded within the vehicle 1. Matrix C is therefore a matrix that depends on measurements available on the vehicle. Vector Y can then be defined by the following formula. TIFF2022552087000009.tif31170

[0066] Based on the kinematics model 21 presented above, the observer 22, and the vector Y, the state vector Xhyb can be calculated. The observer 22 allows for the estimation of the unmeasured components of the hybrid state vector. The observer 22 can be used as input, on the one hand, the closed-loop component FBK calculated in a previous iteration of the method, and on the other hand, the vector Y. Starting from the principle that the vehicle is on a straight line, a reference state vector Xref equal to zero is used. The steering angle of the steering wheel required to follow the curve is supplied by the open-loop component FFD. Furthermore, the measurements must be corrected to "extract" the curve portion of the state vector Xhyb. To do this, the vector Y1, defined by the following formula, can be subtracted from the vector Y. TIFF2022552087000010.tif29170

[0067] In the second substep E62 of the sixth step E6, the closed-loop component FBK is calculated based on a comparison between the vehicle's reference state vector Xref and the hybrid state vector Xhyb. The difference between the reference state vector Xref and the hybrid state vector Xhyb is calculated first. Thus, a vector Xerr, representing the error between the vehicle's theoretical state and its actual state, is obtained. Vector Xerr can therefore be defined by the following formula. Xerr=Xref-Xhyb

[0068] The vector Xerr is then multiplied by the control vector Ks, which is dependent on the vehicle's speed v. The closed-loop components are thus obtained by the subsequent calculation. FBK=Ks.Xerr

[0069] It should be noted that vector Ks is defined as a function of the vehicle's speed. The memory of the electronic control unit can therefore contain different values ​​of vector Ks defined for a given speed value. When the vehicle is actually traveling at a speed intermediate between two given speed values, vector Ks can be interpolated by weighting the vectors Ks stored for speeds greater than the vehicle's actual speed and speeds less than that actual speed.

[0070] In the seventh step E7, the steering angle setpoint δc of the steered wheel is calculated by adding the open-loop component FFD and the closed-loop component FBK. The steering angle setpoint δc can therefore be calculated using the following formula. δc = FBK + FFD

[0071] The steering angle setpoint δc is then sent to the steering device 4, which determines the orientation of the steered wheel according to the steering angle setpoint δc. This setpoint δc is further used for calculating the hybrid state vector Xhyb in the next iteration of the control method.

[0072] It should be noted that the control method described above can be equivalently replaced by a method for calculating the steering angle of the steering wheel, since the steering angle is the orientation of the steering wheel of the vehicle that allows for adjustment of the vehicle's lateral position. Furthermore, the method can be replaced by a method for calculating the steering wheel angle, since the steering wheel angle and the steering angle of the steering wheel are related to each other by a proportional relationship. The control method can also be applied to any quantity that is correlated with the vehicle's lateral position by a known function.

[0073] Thanks to the present invention, the angle calculation of the steering angle setpoint of a steered wheel is achieved in a way that is less dependent on factors that may disrupt the dynamic behavior of a vehicle. The method according to the present invention does not require prior identification of these factors.

[0074] The present invention further relates to a method for calibrating a method for controlling the lateral position of a vehicle. Tests on a road can be performed for the calibration, or in other words, parameterization, of the control method. The calibration of the control method aims, in particular, to determine the values ​​for the previously defined parameters β and γ.

[0075] In the first step C1 of the calibration method, the test is conducted on a first course in which the vehicle experiences a lateral acceleration strictly below the threshold S1. The first step C1 includes a first substep C11 which measures the lateral displacement of the vehicle with respect to a reference track 12 as the vehicle runs on the first course, wherein the distance of interest is defined as equal to zero. The reference lateral displacement yref is thus obtained.

[0076] In the second substep C12, the first course is run again, and the distance of interest is progressively increased as the gain G decreases. This second step C12 is repeated insofar as the lateral displacement y of the vehicle with respect to the reference track is substantially equal to the reference lateral displacement yref. "Substantially equal" should be understood as meaning that the difference between the lateral displacement y and the reference lateral displacement yref is less than a threshold. Thus, the characteristic of the distance of interest can be constructed as a function of the gain G. Based on this characteristic, a parameter β can be defined that allows for the best approach to this characteristic.

[0077] In the second step C2 of the calibration method, the test is conducted on a second course in which the vehicle will experience a lateral acceleration of threshold S1 or greater. The second step C2 includes a first substep C21 which defines the vehicle's distance of interest L. The distance of interest L is then defined to be equal to a predetermined distance Lmax.

[0078] In the second substep C22, the second course is run continuously while progressively increasing the gain G. The second substep C22 is repeated until the lateral deviation of the vehicle with respect to the reference track is less than or equal to a threshold, for example, a threshold of 30 centimeters. The value of the gain G that makes it possible to achieve this lateral deviation with respect to the reference track below this threshold can be defined as the gain value γ.

[0079] Ultimately, through testing on a circuit, the ideal compromise for controlling the lateral position of a vehicle on a traffic lane is to be found. On the one hand, the vehicle follows a reference track without deviating excessively from it. In particular, the vehicle does not excessively shortcut curves. On the other hand, the vehicle is controlled without jerks or unpleasant sudden movements for the rider.

[0080] The present invention is further suitable for application to four-wheel drive vehicles, and requires that a suitable bicycle model be simply used.

Claims

1. A method for controlling the lateral position of a motor vehicle (1), comprising: a step (E41) of calculating the relevance distance (L) of the detection means (8) installed inside said vehicle (1), a step (E5) of calculating a first component (FFD) of the steering angle setpoint (δc) of the steered wheels (2f) of said vehicle (1), said first component (FFD) being an open-loop component of the control system, said first component (FFD) being weighted by a gain (G), said gain (G) being a decreasing function of said attention distance (L); a step (E6) of calculating a second component (FBK) of said steering angle setpoint (δc), said second component (FBK) being a closed-loop component of said control system; A control method comprising:

2. 2. The control method according to claim 1, wherein the gain (G) is greater than or equal to 0 and less than or equal to 1.

3. 3. A control method according to claim 1 or 2, characterized in that the gain (G) is a decreasing linear function of the attention distance (L) and / or that the gain (G) is equal to 1 when the attention distance is 0.

4. 4. A control method according to claim 1, further comprising a step (E7) of calculating the steering angle set point (δc), the steering angle set point (δc) being equal to the sum of the open loop component (FFD) and the closed loop component (FBK).

5. 5. Control method according to claim 1, characterized in that the step (E6) of calculating the second component (FBK) comprises a sub-step (E61) of calculating a state vector (Xhyb) of the vehicle (1), the state vector (Xhyb) comprising a component equal to the lateral deviation (yL) of the vehicle (1) with respect to a reference trajectory (12) at the attention distance (L).

6. 6. The control method according to claim 5, characterized in that the step (E6) of calculating the second component (FBK) of the steering angle setpoint (δc) comprises a substep of multiplying the lateral deviation (yL) of the vehicle (1) at the attention distance (L) by the attention distance (L).

7. The control method includes: a step (E2) of calculating the future lateral acceleration of said vehicle (1); a step (E3) of comparing said lateral acceleration with a threshold value (S1), then a step (E5) of calculating said first component (FFD) of said steering angle setpoint (δc) when said lateral acceleration is greater than or equal to said threshold value (S1), said first component (FFD) being weighted by a gain (G) equal to a predetermined value (γ) independent of said distance of interest (L); - if the lateral acceleration is strictly less than the threshold value (S1), calculating the first component (FFD) of the steering angle setpoint (δc), the first component being weighted by a gain (G), the gain (G) being a decreasing function of the attention distance (L); 7. A control method according to claim 1, comprising:

8. 8. A control method according to claim 7, characterized in that the step (E2) of calculating the future lateral acceleration of the vehicle includes the substep of obtaining the curvature of the traffic lane using a navigation system.

9. 9. Control method according to any one of claims 1 to 8, characterized in that the step (E41) of calculating the remark distance (L) comprises the selection of the minimum value between a predetermined distance (Lmax) and the visual reach (Lrange) of the detection means (8) of the vehicle (1).

10. 10. A computer program product comprising program code instructions stored on a medium, said program being readable by an electronic control unit (6) for carrying out the steps of the control method according to any one of claims 1 to 9, when said program is executed on the electronic control unit (6).

11. A data storage medium readable by an electronic control unit (6) on which a computer program comprising program code instructions for carrying out the control method according to any one of claims 1 to 9 is stored.

12. A steering system (3) characterized in that it comprises hardware means (5, 8) and / or software means for implementing the control method according to any one of claims 1 to 9.

13. A motor vehicle (1) comprising a steering system according to claim 12.

14. A method for calibrating a vehicle (1) according to claim 13, comprising: a first step (C11) of measuring a reference lateral deviation (yref) of the vehicle (1) with respect to a reference trajectory (12) when the vehicle (1) follows a first course, the reference distance (L) being defined as being equal to zero; a second step (C12) of progressively increasing the attention distance (L) and reducing the gain (G) as the vehicle travels along the first course, as long as the lateral deviation (y) of the vehicle relative to the reference trajectory (12) is substantially equal to the reference lateral deviation (yref); characterized in that it comprises and / or a first step (C21) of defining that said distance of interest (L) is equal to a predetermined distance (Lmax); a second step (C22) of gradually increasing said gain (G) as said vehicle follows a second course until said lateral deviation (y) of said vehicle with respect to a reference trajectory (12) is less than or equal to a threshold value; A method comprising:

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