FR3138098A1 - Method and device for determining a yaw rotation speed of a vehicle - Google Patents

Abstract

The present invention relates to a method for determining a yaw rotation speed, called yaw speed, of a vehicle (10) traveling on a current traffic lane (101). For this purpose, first data representative of lateral boundaries (111, 112) of said lane (101) are received and second data representative of a center of said lane (101) are determined. Third data representative of a speed of said vehicle (10) are also received. Finally, fourth data representing a lateral distance at a determined horizon between said center of said traffic lane and said vehicle (10) are determined as a function of said second data and said third data, and fifth data representative of said yaw speed. are determined based on said third data and said fourth data. Figure for abstract: Figure 1

Description

Method and device for determining a yaw rotation speed of a vehicle

The present invention relates to methods and devices for determining the speed of a vehicle, in particular a motor vehicle. The present invention also relates to a method and a device for controlling a driving assistance system, called the ADAS system, of a vehicle, for example a motor vehicle. The present invention also relates to a method and a device for controlling a vehicle, in particular an autonomous vehicle.

Technology background

Road safety is one of the important issues facing our societies. With the increase in the number of vehicles traveling on road networks around the world, regardless of traffic conditions, the risks of accidents and incidents caused by traffic conditions have never been greater.

To improve road safety, certain contemporary vehicles are equipped with driving assistance functions or systems, known as ADAS (from English “Advanced Driver-Assistance System” or in French “Advanced Driving Assistance System”). . ADAS systems, for example, implement processes based on the detection of surrounding obstacles using peripheral sensors on board a vehicle such as cameras, radars, or even lidars (from the English “Light Detection And Ranging”). , or “Detection and estimation of distance by light” in French).

ADAS systems can also take into account navigation data indicating in advance the characteristics of a road, in particular speed limits, hills or even the radius of curvature of turns on the route, so as to optimize the driving of the vehicle in advance. vehicle.

Among these systems, the lane-keeping assistance system, known as the LPA system (from the English “Lane Positioning Assist” or in French “Assistant de positioning dans la queue”) or LKA (from the English “Lane Positioning Assist”). Lane Keeping Assist” or in French “Lane Keeping Assistant”) has the primary function of assisting the driver of the vehicle to follow the route of a traffic lane. In particular, the LPA system tracks certain vehicle parameters in order to maintain its position on a traffic lane. The LPA system follows, for example, a yaw rotation speed, called yaw speed, of the vehicle, so as to adjust the orientation of the vehicle in accordance with the direction of the traffic lane. The vehicle's yaw rate is commonly obtained from a sensor associated with the vehicle's chassis.

In a certain number of situations, for example in the event of absence or malfunction of the yaw rate sensor, the LPA system is thus rendered inoperative, or can cause unexpected behavior of the vehicle, for example oscillations or errors in centering of the vehicle in the traffic lane, resulting from erroneous vehicle yaw speed values.

Summary of the present invention

An object of the present invention is to solve at least one of the problems of the technological background described above.

Another object of the present invention is to reduce the number of sensors necessary for the operation of a vehicle's ADAS systems.

Another object of the present invention is to allow the use of ADAS systems, in particular an LPA system, in vehicles lacking a yaw speed sensor, or whose yaw speed sensor is inoperative.

Another object of the present invention is to reinforce the information received from a vehicle yaw rate sensor.

According to a first aspect, the present invention relates to a method for determining a yaw rotation speed, called yaw speed, of a vehicle traveling on a current lane of a road, the method being implemented by a calculator, the method comprising the following steps:

- reception of first data representative of lateral boundaries of the current traffic lane from a camera on board the vehicle;

- determination of second data representative of a center of the traffic lane based on the first data;

- reception of third data representative of a vehicle speed from an on-board system in the vehicle;

- determination of fourth data representative of a lateral distance at a determined horizon between the center of the traffic lane and the vehicle based on the second data and the third data;

- determination of fifth data representative of the yaw speed as a function of the third data and the fourth data.

It is understood here that the third data includes information on the speed of the vehicle, which excludes the yaw speed that the method seeks to obtain, for example due to the absence of a dedicated sensor on board the vehicle.

The determined horizon corresponds for example to a section of the road, located at a determined longitudinal distance from the vehicle, towards the front of the vehicle according to its direction of travel. The yaw speed is thus obtained from the lateral offset between the center of the traffic lane and the vehicle, and is for example used to orient the vehicle, for example so that, once the vehicle has traveled until reaching the section of the road corresponding to the horizon, the vehicle is located in the center of the traffic lane.

Thus, according to the present invention, the yaw speed of the vehicle is determined in an alternative manner to the use of a dedicated sensor, in particular based on the layout of the lateral boundaries of the current lane of the vehicle. This yaw speed can then be used to maintain the operation of the vehicle's ADAS systems, or to supplement or correct yaw speed information from an on-board sensor of the vehicle.

According to a variant, the determination of the second data comprises a determination of at least one polynomial representation of the current traffic lane, the center of the lane being a function of the polynomial representation.

According to an additional variant, the determination of the fourth data comprises the following steps:

- determination of a longitudinal distance between the vehicle and the horizon based on the third data;

- determination of the lateral distance to the horizon based on the second data and the longitudinal distance.

According to an additional variant, the determination of the fourth data further comprises the following steps:

- determination of a heading on the horizon of the center of the traffic lane with respect to the vehicle based on the second data and the longitudinal distance;

- determination of a lateral acceleration of the vehicle as a function of the heading to the horizon and the lateral distance to the horizon,

the yaw rate being determined as a function of the lateral acceleration and the third data.

According to another variant, the method further comprises the following steps:

- reception of sixth data representative of a yaw rotation speed, called perceived yaw speed, from at least one sensor on board the vehicle;

- comparison of the yaw speed with the perceived yaw speed; And

- determination of a yaw speed correction value based on a result of the comparison.

According to yet another variant, the method further comprises a step of controlling a driving assistance system, called the ADAS system, of the vehicle as a function of the yaw speed.

According to a second aspect, the present invention relates to a device for determining a yaw rotation speed of a vehicle traveling on a current traffic lane of a road, the device comprising a memory associated with a processor configured for updating implementing the steps of the method according to the first aspect of the present invention.

According to a third aspect, the present invention relates to a vehicle, for example of the automobile type, comprising a device as described above according to the second aspect of the present invention.

According to a fourth aspect, the present invention relates to a computer program which comprises instructions adapted for the execution of the steps of the method according to the first aspect of the present invention, in particular when the computer program is executed by at least one processor.

Such a computer program can use any programming language, and be in the form of a source code, an object code, or an intermediate code between a source code and an object code, such as in partially compiled form, or in any other desirable form.

According to a fifth aspect, the present invention relates to a computer-readable recording medium on which is recorded a computer program comprising instructions for executing the steps of the method according to the first aspect of the present invention.

On the one hand, the recording medium can be any entity or device capable of storing the program. For example, the medium may comprise a storage means, such as a ROM memory, a CD-ROM or a ROM memory of the microelectronic circuit type, or even a magnetic recording means or a hard disk.

On the other hand, this recording medium can also be a transmissible medium such as an electrical or optical signal, such a signal being able to be conveyed via an electrical or optical cable, by conventional or terrestrial radio or by self-directed laser beam or by other ways. The computer program according to the present invention can in particular be downloaded onto an Internet type network.

Alternatively, the recording medium may be an integrated circuit in which the computer program is incorporated, the integrated circuit being adapted to execute or to be used in executing the method in question.

Brief description of the figures

Other characteristics and advantages of the present invention will emerge from the description of the particular and non-limiting examples of embodiment of the present invention below, with reference to the attached Figures 1 to 3, in which:

schematically illustrates a portion of road on which a vehicle travels, according to a particular and non-limiting example of embodiment of the present invention;

schematically illustrates a device configured to determine a yaw rotation speed of the vehicle of the , according to a particular and non-limiting embodiment of the present invention;

illustrates a flowchart of the different stages of a method for determining a yaw rotation speed of the vehicle of the , according to a particular and non-limiting embodiment of the present invention.

Description of the implementation examples

A method and a device for determining a yaw rotation speed of a vehicle will now be described in what follows with reference jointly to Figures 1 to 3. The same elements are identified with the same reference signs throughout. throughout the description which follows.

According to a particular and non-limiting example of embodiment of the present invention, the determination of a yaw rotation speed, called yaw speed, of a vehicle traveling on a current lane of a road comprises the reception, by the vehicle, first data representative of lateral boundaries of the current traffic lane. These first data are advantageously received from a camera on board the vehicle, this camera having in its field of vision the road surface on which the vehicle is traveling. The first data correspond for example to information making it possible to delimit and position the lateral limits of the current traffic lane, in relation to the vehicle.

Second data representative of a center of the taxiway are obtained from the first data. The center of the traffic lane is for example defined as an intermediate position between the lateral boundaries of the current traffic lane, and thus corresponds to a layout of a central position of the current traffic lane. The center of the traffic lane corresponds for example to a position objective for a system to help keep the vehicle in a lane.

Third data representative of a vehicle speed are also received from a system embedded in the vehicle, for example from a speed sensor or from a navigation system embedded in the vehicle. The third data includes, for example, information representative of a longitudinal speed of the vehicle. Depending on the second data and the third data, fourth data representative of a lateral distance, at a determined horizon, between the center of the traffic lane and the vehicle are determined. This lateral distance thus corresponds to the movement of the center of the lane relative to the position of the vehicle, along a portion of the traffic lane located in front of the vehicle and corresponding to the horizon. The longitudinal speed of the vehicle makes it possible, for example, to position the horizon, in particular so as to obtain a lower yaw speed when the longitudinal speed of the vehicle is high.

Fifth data representative of the yaw speed are then determined based on the third data and the fourth data. This yaw speed, corresponding to an estimate of the yaw speed as a function of the layout of the traffic lane, is for example obtained by combining the lateral distance with a tangential speed of the vehicle, that is to say the speed of the vehicle along an axis perpendicular to the direction of movement of the vehicle.

The determination of the yaw speed of the vehicle can therefore be carried out in the absence of a dedicated sensor, based mainly on the layout of the traffic lane and on other vehicle speed information, distinct and more easily accessible than its yaw speed. The vehicle's ADAS systems, particularly the LPA system, can therefore operate under more varied conditions, including when the vehicle's yaw rate sensor is unavailable.

There schematically illustrates an environment in which a vehicle 10 operates, according to a particular and non-limiting embodiment of the present invention.

There illustrates a vehicle 10, for example a motor vehicle, traveling on a portion of the road in environment 1. According to other examples, the vehicle 10 corresponds to a coach, a bus, a truck, a utility vehicle or a motorcycle, that is to say a vehicle of the motorized land vehicle type.

Vehicle 10 corresponds to a vehicle circulating under the full supervision of a driver or circulating in an autonomous or semi-autonomous mode. The vehicle 10 circulates according to a level of autonomy equal to 0 or according to a level of autonomy ranging from 1 to 5 for example, according to the scale defined by the American federal agency which has established 5 levels of autonomy ranging from 1 to 5, level 0 corresponding to a vehicle having no autonomy, whose driving is under the total supervision of the driver, level 1 corresponding to a vehicle with a minimum level of autonomy, whose driving is under the supervision of the driver with minimal assistance from an ADAS system, and level 5 corresponding to a completely autonomous vehicle.

The 5 levels of autonomy in the classification of the federal agency responsible for road safety are:

- level 0: no automation, the vehicle driver has full control over the main functions of the vehicle (engine, accelerator, steering, brakes);

- level 1: driver assistance, automation is active for certain vehicle functions, the driver maintaining overall control over vehicle driving; cruise control is part of this level, like other aids such as ABS (anti-lock braking system) or ESP (programmed electro-stabilizer);

- level 2: automation of combined functions, the control of at least two main functions is combined in the automation to replace the driver in certain situations; for example, adaptive cruise control combined with lane centering allows a vehicle to be classified level 2, as does automatic parking assistance;

- level 3: limited autonomous driving, the driver can cede complete control of the vehicle to the automated system which will then be in charge of critical safety functions; however, autonomous driving can only take place in certain specific environmental and traffic conditions (only on motorways for example);

- level 4: complete autonomous driving under conditions, the vehicle is designed to ensure all critical safety functions alone over a complete journey; the driver provides a destination or navigation instructions but is not required to make himself available to regain control of the vehicle;

- level 5: completely autonomous driving without driver assistance in all circumstances.

According to a particular embodiment, the vehicle 10 circulates in a semi-autonomous or autonomous mode, that is to say with a level of autonomy greater than or equal to 2 according to the classification above.

According to the example of the , the vehicle 10 travels on a portion of the road comprising a plurality of lanes 101, 102. The vehicle 10 travels on a current traffic lane 101, an adjacent side lane 102 being to the left of the current traffic lane 102 (in the direction circulation of the vehicle 10).

The notions of right and left are defined according to the direction of movement of the vehicle 10. The traffic lane 101 corresponds for example to the "slowest" lane and the traffic lane 102 corresponds according to this example to the "slowest" lane. fast ". The “slowest” lane is on the right in countries where vehicles travel in the right lane (countries such as France for example). The “slowest” lane of traffic is on the left in countries where vehicles travel in the left lane (countries such as the United Kingdom for example).

The example of the corresponds to an example where vehicles travel on the right, as in France. The invention is, however, not limited to such an example and extends to all road configurations, including those where vehicles travel on the left.

A lane 101, 102 of the road portion corresponds to a traffic lane, that is to say a lane provided for the circulation of vehicles, or to any type of lane, for example an exit lane of a restricted access road (also called expressway road), a motorway exit lane or an emergency lane, noted BAU.

According to the example of the , the portion of road corresponds to a portion of motorway or a portion of expressway road with several lanes of traffic for each direction of traffic. According to this particular example, each of the tracks 101 and 102 correspond to traffic lanes, the BAU (to the right of track 101) not being shown on the .

Each of the lanes 101 and 102 is marked or delimited by lateral boundaries 111, 112 and 113 which correspond for example to marking lines on the ground or to safety barriers (or barriers).

According to the particular example of the , each of the lateral boundaries 111 to 113 are of the ground marking line type. The ground marking lines are also called horizontal markings and correspond to a set of lines 111, 112 and 113 drawn on the ground. The ground marking lines 111 to 113 can be of several types, for example edge lines or center lines, with different characteristics. The ground marking lines can thus be of the continuous line, discontinuous line or mixed line type (comprising a continuous line and a discontinuous line parallel to the continuous line). A dashed line may also have different characteristics, with spacing lengths between lines varying from one type of dashed line to another and/or line length varying from one type to another.

Thus, according to the example of the , the current traffic lane 101 is delimited on the left by a discontinuous line 112. This discontinuous line 112 marks the separation between the current traffic lane 101 and the adjacent side lane 102 also corresponding to a traffic lane. The current traffic lane 101 is delimited on the right by a first continuous line 111 and the adjacent side lane 102 is delimited on the left by a second continuous line 113.

The distance of a delimitation relative to the vehicle 10 is determined for example in a reference point centered on the vehicle 10 having as longitudinal axis the axis of movement of the vehicle 10 along the traffic lane 101 and as lateral axis (also called transverse axis ) an axis perpendicular to the longitudinal axis. The distance between the vehicle 10 and a boundary corresponds to the distance between a reference point of the vehicle 10 (for example the middle of the front axle or the middle of the rear axle of the vehicle 10) and the line along the axis lateral.

The vehicle 10 advantageously carries one or more driving assistance systems, called ADAS (from English “Advanced Driver-Assistance System” or in French “Advanced Driving Assistance System”). The vehicle in particular incorporates a system for assisting in maintaining a lane, known as the LPA system (from the English “Lane Positioning Assist” or in French “Assistant de positioning dans la queue”) or LKA (from the English “Lane Keeping Assist” or in French “Lane Keeping Assistant”). Such a system is based in particular on the detection and recognition of the marking lines on the ground to keep the vehicle 10 correctly positioned within the current traffic lane 101.

Among the checks carried out by the LPA system to keep the vehicle 10 in the current traffic lane 101, the LPA system controls the yaw rotation speed, called yaw speed, of the vehicle 10, in other words the rotation towards the left or towards the left. right of the vehicle 10. The vehicle 10 commonly obtains a measurement of its yaw speed from a dedicated on-board sensor, for example a sensor associated with the chassis of the vehicle 10, so as to adjust and control the orientation of the vehicle 10.

One problem that arises is that measuring the yaw rate of vehicle 10 is not always reliable. Thus, when the vehicle 10 does not have a working yaw speed sensor, the associated ADAS systems, in particular the LPA system, are rendered inactive. In other situations, if the yaw speed sensor returns erroneous values, the rotation of the vehicle 10 is distorted and its behavior becomes unpredictable. An on-board LPA system operating from an erroneous measurement of yaw speed can thus generate oscillations of the vehicle 10 while it tries to center itself on the current traffic lane 101. The process described below offers a solution to this issue.

The vehicle 10 advantageously carries a ground marking detection system. Such a system is for example coupled to the LPA system or integrated into the LPA system. According to another example, such a system is coupled to a semi-automatic lane change system, called the SALC system (from the English “Semi-Automatic Lane Change”), or integrated into a SALC system, the SALC system. being embedded in the vehicle 10. Such a ground marking detection system receives data from one or more first cameras embedded in the vehicle 10 and configured for the acquisition of images of the traffic lane taken by the vehicle 10 , for example the portion of the road located at the front and/or on the sides of the vehicle 10. The road marking detection system is thus configured to detect the road markings in the environment of the vehicle 10. Processing of The image is applied to the images obtained from the first camera(s) of the ground marking detection system to determine the presence of lines on the ground and to classify these lines into different categories, for example to determine whether the lines on the ground correspond to shore lines or center lines for example. An example of image processing to detect lines on the ground is for example described in document WO2017194890A1.

In the process described below, only the detection of the presence of ground marking lines is taken into account. According to a variant, the classification of the detected lines is also implemented, for example to confirm the determination of the line type as obtained according to the process described below.

According to an alternative embodiment, the vehicle 10 also carries one or more of the following sensors:

- one or more millimeter wave radars arranged on the vehicle 10, for example at the front, at the rear, on each front/rear corner of the vehicle; each radar is adapted to emit electromagnetic waves and to receive the echoes of these waves returned by one or more objects (for example the barriers 110), with the aim of detecting obstacles or other objects and their distances with respect to the vehicle 10; and or

- one or more LIDAR(s) (from the English “Light Detection And Ranging”, or “Detection and estimation of the distance by light” in French), a LIDAR sensor corresponding to an optoelectronic system composed of a transmitter device laser, a receiving device comprising a light collector (to collect the part of the light radiation emitted by the transmitter and reflected by any object located in the path of the light rays emitted by the transmitter) and a photodetector which transforms light collected as an electrical signal; a LIDAR sensor thus makes it possible to detect the presence of objects (for example barriers 110) located in the emitted light beam and to measure the distance between the sensor and each detected object.

A process for determining a yaw speed of the vehicle 10 traveling on the current traffic lane 101 of the road 1 is advantageously implemented by the vehicle 10, that is to say by a computer or a combination of computers of the on-board system of the vehicle 10, for example by the computer(s) in charge of controlling the LPA system or by the computer(s) in charge of the detection system (and classification if applicable) of the ground marking lines.

According to a particular and non-limiting embodiment, such a process is part of a broader process of controlling the ADAS system, for example the LPA system, of the vehicle 10. The vehicle 10 thus implements, in this example, a control process of the ADAS system as a function of the yaw speed determined by the process according to the invention. In particular, the LPA system of the first vehicle 10 can determine a trajectory of the vehicle 10 as a function of the yaw speed determined by the process.

According to a variant embodiment, such a control process of the ADAS system is configured to use a yaw speed measurement from a yaw speed sensor on board the vehicle 10. When this yaw speed measurement is unavailable, the control process of the ADAS system then uses the yaw speed determined according to the invention until the yaw speed measurement becomes available again.

In a first operation, first data representative of the lateral boundaries 111, 112 of the current traffic lane 101 are received. The first data are for example part of a set of data representative of the set of lateral delimitations 111, 112, 113 of the plurality of tracks 101, 102, and making it possible to establish the number, layout and profile of the plurality of channels 101, 102.

These first data are for example received from one or more sensors, in particular from one or more cameras on-board in the vehicle 10, via one or more communication buses of the on-board system of the vehicle 10, for example a bus-type communication bus data CAN (from the English “Controller Area Network” or in French “Réseau de controllers”), CAN FD (from the English “Controller Area Network Flexible Data-Rate” or in French “Network of data rate controllers”) flexible"), FlexRay (according to ISO 17458), Ethernet (according to ISO/IEC 802-3) or LIN (from English "Local Interconnect Network", or in French "Réseau interconnectée local").

According to a variant embodiment, part of the data is received from the camera(s) and another part is received from radar and/or LIDAR type object detection sensors (from the English “Light Detection And Ranging”, or “Detection and estimation of distance by light” in French). This variant is for example implemented when lateral boundaries of the slide or barrier type are present on one edge of the road portion.

In a second operation, second data representative of a center of the taxiway 101 are determined based on the first data. In other words, the first data make it possible to determine a central position of the current traffic lane 101, for example located equidistant from the lateral boundaries 111, 112.

According to a variant embodiment, the current traffic lane is represented by a polynomial of degree 3 in the form P(x) = C ₀ + C ₁ * x + C ₂ * x² + C ₃ * x ³ , with C ₀ , C ₁ , C ₂ and C ₃ the coefficients of the polynomial. According to a first variant, a polynomial represents the center of the current traffic lane 101, which is thus associated with a single polynomial describing its route. According to a second variant, each polynomial represents the lateral boundaries 111, 112, the current traffic lane 101 being associated with two polynomials describing its limits.

The coefficients C ₀ , C ₁ , C ₂ and C ₃ come from the on-board camera(s) of the vehicle 10 or from the ground marking detection system using images from this camera(s).

The coefficient C ₀ represents for example a distance between the center of the vehicle 10 and each boundary considered. The coefficient C ₁ represents an angle between the trajectory of the vehicle 10 and a tangent to the traffic lane (the heading). The coefficient C ₂ represents a radius of curvature and the coefficient C ₃ represents a derivative of this radius of curvature.

Thus, line 111 is for example defined by the polynomial P ₁₁₁ (x) = C _{0_111} + C _{1_111} * x + C _{2_111} * x² + C _{3_111} * x ³ and line 112 is defined by the polynomial P ₁₁₂ (x) = C _{0_112} + C _{1_112} * x + C _{2_112} * x² + C _{3_112} * x ³ .

According to a particular embodiment, the center of the current traffic lane 101 is obtained from the polynomials of the lateral boundaries 111, 112.

The center of the current traffic lane 101 is for example obtained by the following equation:

In a third operation, third data representative of a speed of the vehicle 10 are received. The third data include for example information representative of the longitudinal speed of the vehicle 10, that is to say the speed of the vehicle 10 along a first axis defined by the direction of travel of the current traffic lane 101. The third data optionally also include information representative of the tangential speed of the vehicle 10, that is to say along a second axis perpendicular to the first axis and included in the plane defined by the current traffic lane 101.

The vehicle 10 carries, for example, one or more of the following systems:

- an odometer configured to determine the distance traveled by the vehicle 10, the speed of the vehicle 10 being derived from the distance traveled over a given time interval; and or

- a speedometer comprising for example a speed sensor output from the gearbox or one or more speed sensors connected to the wheels; and or

- an inertial unit, called IMU (from the English “Inertial Measurement Unit” or in French “Unité demeasurement inertielle”); and or

- an on-board navigation system, the speed of the vehicle 10 being derived from the evolution of the position of the vehicle 10 within the road environment.

The third data are then obtained by communication between the vehicle's on-board computer and the on-board system(s).

In a fourth operation, fourth data representative of a lateral distance, at a determined horizon, between the center of the track and the vehicle 10 are determined as a function of the second data and the third data. Fifth data representative of the yaw speed of the vehicle 10 are then determined in a fifth operation based on the third data and the fourth data.

It is understood here that the horizon corresponds to a section of the traffic lane 101 arranged in front of the vehicle 10 and corresponding to a reference position for controlling the vehicle 10, in particular for its maintenance in the current traffic lane 101, and that the lateral distance between the center of the lane and the vehicle 10 on the horizon depends on the evolution of the position of the center of the traffic lane 101 in the reference frame of the vehicle 10.

Thus, the yaw speed, necessary to orient the vehicle 10 with respect to the traffic lane 101, can be obtained without having a dedicated sensor, based on the lateral distance to the horizon between the center of the lane traffic 101 and vehicle 10, as well as on the speed of vehicle 10.

According to an exemplary embodiment, the third data makes it possible to determine the horizon, while the second data makes it possible to establish the lateral distance between the center of the lane and the vehicle 10 at this horizon. The horizon is for example defined firstly as a function of a time interval between two positions of the vehicle 10, and secondly as a function of a distance traveled by the vehicle during this time interval. We thus define a time interval Δt between the vehicle 10 and the horizon and a longitudinal distance ΔL _x between the vehicle 10 and the horizon, the time interval Δt and the longitudinal distance ΔL _x being linked by the following formula:

With V _x the longitudinal speed of the vehicle 10 obtained from the third data.

According to yet another example, the time interval Δt and/or the longitudinal distance ΔL _x are obtained from a correspondence table associating a time interval Δt and/or a longitudinal distance ΔL _x with a plurality of speed values of the vehicle 10 data, or from a function defining Δt=f ₁ (V _x ) and/or ΔL=f ₂ (V _x ), for example a function constructed by interpolation of points taken from a correspondence table .

According to another example, the time interval Δt corresponds to a fixed value recorded in a memory in communication with the vehicle computer 10, the longitudinal distance ΔL _x being obtained from the fixed time interval Δt and the speed of the vehicle 10.

The lateral distance is then determined by combining the longitudinal distance ΔL _x and the second data, for example from the polynomial of the center of the current traffic lane 101 as defined above, according to the formula:

With ΔL _y the lateral distance to the horizon.

According to yet another particular and non-limiting example of embodiment, the determination of the lateral distance to the horizon is completed by the determination of a heading at the horizon of the center of the traffic lane 101 with respect to the vehicle 10 , that is to say a lateral speed from the center of the traffic lane 101, in the reference of the vehicle 10, to the horizon. The heading at the horizon ΔV is for example defined _there according to the following formula derived from the polynomial of the center of the current traffic lane 101:

From the heading to the horizon, it is also possible to obtain a lateral acceleration at the horizon ΔA _y , notably defined as follows:

And the yaw speed ω is, in this same example, given by:

With V _y the tangential speed of the vehicle 10 obtained from the third data.

Thus, the method according to the invention makes it possible to calculate a yaw speed of the vehicle 10 based mainly on the layout of the current traffic lane 101, as well as on other more accessible measurements of the speed of the vehicle 10. Obviously , it is conceivable that the yaw speed of the vehicle 10 is obtained according to other formulas equivalent to those of the exemplary embodiments stated. The yaw speed of the vehicle 10 can thus be obtained in the event of absence or malfunction of the dedicated sensor.

According to a variant embodiment, the vehicle 10 also receives, in a sixth operation, sixth data representative of a yaw rotation speed, called perceived yaw speed, from at least one sensor on board the vehicle 10, for example a sensor yaw speed associated with the chassis of the vehicle 10. The yaw speed obtained according to the method is then compared with the perceived yaw speed so as to determine a yaw speed correction value. In other words, the perceived yaw speed can be confirmed, invalidated or corrected by the yaw speed obtained according to the method, in particular so as to identify a malfunction of the yaw speed sensor, to calibrate the sensor or even to maintain the operation of the yaw speed sensor. yaw speed sensor in the event of a malfunction, while limiting the requirements for executing the method according to the invention.

The yaw speed obtained or corrected according to the invention can then be used for the implementation of a method of controlling an ADAS system of the vehicle 10, for example the LPA system.

There schematically illustrates a device 2 configured to determine a yaw speed of a vehicle, for example the vehicle traveling on the road of the , according to a particular and non-limiting embodiment of the present invention. The device 2 corresponds for example to a device on board the vehicle 10, for example a computer.

The device 2 is for example configured for the implementation of the operations described with regard to the and/or steps of the process described with regard to the . Examples of such a device 2 include, without being limited to, on-board electronic equipment such as an on-board computer of a vehicle, an electronic computer such as an ECU (“Electronic Control Unit”), a telephone smart (from the English “smartphone”), a tablet, a laptop. The elements of device 2, individually or in combination, can be integrated into a single integrated circuit, into several integrated circuits, and/or into discrete components. Device 2 can be produced in the form of electronic circuits or software (or computer) modules or even a combination of electronic circuits and software modules.

The device 2 comprises one (or more) processor(s) 20 configured to execute instructions for carrying out the steps of the method and/or for executing the instructions of the software(s) embedded in the device 2. The processor 20 may include integrated memory, an input/output interface, and various circuits known to those skilled in the art. The device 2 further comprises at least one memory 21 corresponding for example to a volatile and/or non-volatile memory and/or comprises a memory storage device which may comprise volatile and/or non-volatile memory, such as EEPROM, ROM , PROM, RAM, DRAM, SRAM, flash, magnetic or optical disk.

The computer code of the embedded software(s) comprising the instructions to be loaded and executed by the processor is for example stored on memory 21.

According to different particular and non-limiting examples of embodiment, the device 2 is coupled in communication with other similar devices or systems and/or with communication devices, for example a TCU (from the English “Telematic Control Unit” or in French “Telematic Control Unit”), for example via a communications bus or through dedicated input/output ports.

According to a particular and non-limiting exemplary embodiment, the device 2 comprises a block 22 of interface elements for communicating with external devices, for example a remote server or the "cloud", or the vehicle 10 when the device 2 corresponds to a smartphone or tablet for example. The interface elements of block 22 include one or more of the following interfaces:

- RF radio frequency interface, for example of the Wi-Fi® type (according to IEEE 802.11), for example in the 2.4 or 5 GHz frequency bands, or of the Bluetooth® type (according to IEEE 802.15.1), in the band frequency at 2.4 GHz, or Sigfox type using UBN radio technology (from English Ultra Narrow Band, in French ultra narrow band), or LoRa in the 868 MHz frequency band, LTE (from English “ Long-Term Evolution” or in French “Long-Term Evolution”), LTE-Advanced (or in French LTE-advanced);

- USB interface (from the English “Universal Serial Bus” or “Bus Universel en Série” in French);

- HDMI interface (from the English “High Definition Multimedia Interface”, or “Interface Multimedia Haute Definition” in French).

According to another particular and non-limiting example of embodiment, the device 2 comprises a communication interface 23 which makes it possible to establish communication with other devices (such as other computers of the on-board system or on-board sensors) via a channel communication interface 230. The communication interface 23 corresponds for example to a transmitter configured to transmit and receive information and/or data via the communication channel 230. The communication interface 23 corresponds for example to a wired network of the type CAN (from the English “Controller Area Network” or in French “Réseau de controlleres”), CAN FD (from the English “Controller Area Network Flexible Data-Rate” or in French “Réseau de controllers à rate flexible data” ), FlexRay (standardized by the ISO 17458 standard), Ethernet (standardized by the ISO/IEC 802-3 standard) or LIN (from the English “Local Interconnect Network”, or in French “Local Interconnected Network”).

According to a particular and non-limiting embodiment, the device 2 can provide output signals to one or more external devices, such as a display screen, touch or not, one or more speakers and/or other devices (projection system) via respective output interfaces. According to one variant, one or the other of the external devices is integrated into device 2.

There illustrates a flowchart of the different stages of a method for determining a yaw speed of a vehicle traveling on a current lane of a road, according to a particular and non-limiting exemplary embodiment of the present invention. The method is for example implemented by a device on board the vehicle 10 or by the device 2 of the .

In a first step 31, first data representative of lateral boundaries of the current traffic lane are received from a camera on board the vehicle.

In a second step 32, second data representative of a center of the traffic lane are determined based on the first data.

In a third step 33, third data representative of a vehicle speed are received from a system embedded in the vehicle.

In a fourth step 34, fourth data representative of a lateral distance at a determined horizon between the center of the traffic lane and the vehicle are determined based on the second data and the third data.

In a fifth step 35, fifth data representative of the yaw speed are determined based on the third data and the fourth data.

According to a variant, the variants and examples of the operations described in relation to the apply to the stages of the process of .

Of course, the present invention is not limited to the exemplary embodiments described above but extends to a method for determining a yaw speed of a vehicle which would include secondary steps without thereby departing from the scope of the present invention. The same would apply to a device configured to implement such a process.

The present invention also relates to an ADAS system, for example an LPA system, comprising device 2 of the .

The present invention also relates to a vehicle, for example an automobile or more generally an autonomous vehicle with a land engine, comprising the device 2 of the or the ADAS system, for example LPA, above.

Claims (10)

Method for determining a yaw rotation speed, called yaw speed, of a vehicle (10) traveling on a current traffic lane (101) of a road (1), said method comprising the following steps:
- reception (31) of first data representative of lateral boundaries (111, 112) of said current traffic lane (101) from a camera on board said vehicle (10);
- determination (32) of second data representative of a center of said traffic lane (101) as a function of said first data;
- reception (33) of third data representative of a speed of said vehicle (10) from a system embedded in said vehicle (10);
- determination (34) of fourth data representative of a lateral distance at a determined horizon between said center of said traffic lane and said vehicle (10) as a function of said second data and said third data;
- determination (35) of fifth data representative of said yaw speed as a function of said third data and said fourth data. Method according to claim 1, wherein said determination (32) of said second data comprises a determination of at least one polynomial representation of said current traffic lane (101), said center of said lane (101) being a function of said polynomial representation . Method according to claim 1 or 2, wherein said determination (34) of said fourth data comprises the following steps:
- determination of a longitudinal distance between said vehicle (10) and said horizon as a function of said third data;
- determination of said lateral distance to said horizon as a function of said second data and said longitudinal distance. The method of claim 3, wherein said determination (34) of said fourth data further comprises the following steps:
- determination of a heading to said horizon of said center of said traffic lane (101) with respect to said vehicle (10) as a function of said second data and of said longitudinal distance;
- determination of a lateral acceleration of said vehicle (10) as a function of said heading to said horizon and said lateral distance to said horizon,
said yaw speed being determined as a function of said lateral acceleration and said third data. Method according to one of claims 1 to 4, which further comprises the following steps:
- reception of sixth data representative of a yaw rotation speed, called perceived yaw speed, from at least one sensor on board said vehicle (10);
- comparison of said yaw speed with said perceived yaw speed; And
- determination of a yaw speed correction value based on a result of said comparison. Method according to one of claims 1 to 5, further comprising a step of controlling a driving assistance system, called the ADAS system, of said vehicle (10) as a function of said yaw speed. Computer program comprising instructions for implementing the method according to any one of the preceding claims, when these instructions are executed by a processor. Computer-readable recording medium on which a computer program is recorded comprising instructions for carrying out the steps of the method according to one of claims 1 to 6. Device (2) for determining a yaw rotation speed of a vehicle traveling on a current lane of a road, said device (2) comprising a memory (21) associated with at least one processor (20) configured for the implementation of the steps of the method according to any one of claims 1 to 6. Vehicle (10) comprising the device (2) according to claim 9.