METHOD FOR AUTOMATED MANAGEMENT OF THE LONGITUDINAL SPEED OF A VEHICLE

A method for automated management of the longitudinal speed of a first vehicle travelling on a first lane includes: detecting an intention of a second vehicle travelling on a second lane adjacent to the first lane to perform an insertion maneuver on the first lane; estimating a corrected longitudinal distance, the corrected longitudinal distance corresponding to the longitudinal distance that will separate the first vehicle from the second vehicle at the end of the insertion maneuver, the corrected longitudinal distance being calculated as a function of a measured longitudinal distance between the first vehicle and the second vehicle, and as a function of a relative longitudinal speed measured between the second vehicle and the first vehicle; and calculating a longitudinal speed setpoint of the first vehicle as a function of the corrected longitudinal distance.

The invention relates to a method for the automated management of the longitudinal speed of a vehicle. The invention also relates to a device for the automated management of the longitudinal speed of a vehicle. The invention also relates to a motor vehicle comprising such an automated management device.

Driving assistance technologies are becoming increasingly widespread and are no longer limited to high-specification15vehicles.

These technologies make it possible to simplify the driving of motor vehicles and/or to make the behavior of the drivers of the vehicles more reliable.

Some automated speed management systems are commonly installed in modern vehicles, these generally operating on the basis of regulating distance between the vehicle fitted therewith, also called ego vehicle, and the vehicle in front thereof in its traffic lane, called target.

Some automated speed management systems also take into consideration targets performing a cut-in maneuver before the cut-in thereof into the lane of the ego vehicle takes place. However, anticipating the speed regulation with respect to a target entering into the lane of the ego vehicle may generate discomfort when driving.

The aim of the invention is to provide a system and a method for the automated management of the longitudinal speed of a vehicle that rectifies the abovementioned drawbacks.

A first subject of the invention is a method for managing longitudinal speed that produces a comfortable and reassuring regulation for the passengers in the vehicle.

To this end, the invention relates to a method for the automated management of the longitudinal speed of a first vehicle traveling in a first lane. The method comprises the following steps:a first step of detecting an intention of a second vehicle traveling in a second lane adjacent to the first lane to perform a cut-in maneuver into the first lane,a second step of estimating a corrected longitudinal distance, the corrected longitudinal distance corresponding to the longitudinal distance that will separate the first vehicle from the second vehicle at the end of the cut-in maneuver, the corrected longitudinal distance being computed based on a longitudinal distance measured between the first vehicle and the second vehicle, and based on a relative longitudinal speed measured between the second vehicle and the first vehicle,a third step of computing a longitudinal speed setpoint for the first vehicle based on the corrected longitudinal distance.

The first detection step may comprise a sub-step of computing a time to line crossing, and then a sub-step of comparing the time to line crossing with a predefined threshold.

The corrected longitudinal distance computed in the second step may depend on the measured longitudinal distance, on the measured relative longitudinal speed and on the time to crossing.

The corrected longitudinal distance computed in the second step may be equal to the sum of the measured longitudinal distance and the product of the measured relative longitudinal speed and the time to crossing.

The first detection step may comprise a sub-step of detecting visual indicators on the second vehicle signaling a cut-in maneuver, in particular detection of the use of flashing lights.

The method may comprise a step of comparing the speed of the first vehicle and the speed of the second vehicle, the longitudinal speed setpoint computed in the third step being a strong deceleration setpoint if the speed of the second vehicle is strictly less than the speed of the first vehicle, and the longitudinal speed setpoint computed in the third step being a weak deceleration setpoint if the speed of the second vehicle is strictly greater than the speed of the first vehicle.

The method may comprise:a step of computing a first reference longitudinal speed based on the corrected longitudinal distance,a step of detecting at least one third vehicle in traffic around the first vehicle,a step of computing at least one second reference longitudinal speed based on the speed of the at least one third vehicle.
The longitudinal speed setpoint computed in the third step may be equal to the minimum of the first reference longitudinal speed and the at least one second reference longitudinal speed.

The second vehicle and the at least one third vehicle may be situated ahead of the first vehicle.

The invention also relates to a device for the automated management of the longitudinal speed of a vehicle, the device comprising hardware and/or software elements implementing a method as defined above.

The invention also relates to a motor vehicle comprising a device for the automated management of the longitudinal speed of a vehicle as defined above.

The invention also relates to a computer program product comprising program code instructions recorded on a computer-readable medium for implementing the steps of the method defined above when said program runs on a computer and/or to a computer program product able to be downloaded from a communication network and/or recorded on a computer-readable and/or computer-executable data medium, characterized in that it comprises instructions that, when the program is executed by the computer, prompt said computer to implement the method defined above.

The invention also relates to a computer-readable data recording medium on which is recorded a computer program comprising program code instructions for implementing the method defined above and/or to a computer-readable recording medium comprising instructions that, when they are executed by a computer, prompt said computer to implement the method defined above.

The invention also relates to a signal of a data medium carrying the computer program product defined above.

One embodiment of a vehicle equipped with a means for implementing a method for the automated management of longitudinal speed is described below with reference toFIG.1.

The motor vehicle10is a motor vehicle of any type, in particular a leisure vehicle or a utility vehicle. In this description of one embodiment, the vehicle comprising the means for implementing the invention is called “ego” vehicle. This name makes it possible only to distinguish it from other nearby vehicles and does not confer any technical limitation per se on the motor vehicle10.

The first motor vehicle10or ego vehicle10comprises a system1for the automated management of the longitudinal speed of a motor vehicle.

The system1for the automated management of the longitudinal speed of a motor vehicle may form part of a more global driving assistance system9.

The system1for the automated management of the longitudinal speed of a motor vehicle comprises primarily the following elements:a detection means3for detecting vehicles traveling in the lane of the motor vehicle10, called main lane, and in the traffic lanes, called adjacent lanes, located on either side of the main lane,a microprocessor2,a memory6.

The system1for the automated management of the longitudinal speed of a motor vehicle, and particularly the microprocessor2, comprises primarily the following modules:a module21for detecting an intention of a second vehicle traveling in a second lane adjacent to the first lane to perform a cut-in maneuver into the first lane, this module being able to interact with the detection means3,a module22for estimating a corrected longitudinal distance that will separate the ego vehicle10from the second vehicle at the end of the cut-in maneuver, this module being able to interact with the detection means3,a module23for computing a longitudinal speed setpoint for the ego vehicle based on said corrected longitudinal distance, this module being able to interact with the detection means.

The motor vehicle10, in particular the system1for the automated management of the longitudinal speed of a motor vehicle, preferably comprises all of the hardware and/or software elements configured so as to implement the method defined in the subject of the invention or the method described further below.

The detection means3may comprise for example a radar, and/or a lidar, and/or a camera and/or any other type of sensor suitable for detecting targets in the environment of the ego vehicle.

The detection means3may provide measurements to the microprocessor2, including:the longitudinal distance between the ego vehicle and the surrounding vehicles,the longitudinal and lateral speeds of the surrounding vehicles,the longitudinal and lateral acceleration of the surrounding vehicles, andthe relative longitudinal speed of the surrounding vehicles with respect to the ego vehicle.

As a variant, some of these measurements could be computed by the microprocessor on the basis of measurements supplied by the detection means3. These measurements may be repeated indefinitely at a given frequency.

The microprocessor2may furthermore also receive information relating to the longitudinal speed of the ego vehicle, for example by way of speed sensors of the ego vehicle connected to the system1. The microprocessor2may also receive information relating to the lateral distance between the ego vehicle and surrounding vehicles and/or information for positioning the ego vehicle in a reference frame, in particular for positioning the ego vehicle with respect to demarcation lines.

The module23for computing a longitudinal speed setpoint is able to transmit control orders to an engine4or to a braking system5of the vehicle so as to control the longitudinal speed of the ego vehicle.

The system1for the automated management of the longitudinal speed of a motor vehicle comprises a memory6. The memory6constitutes a recording medium able to be read by a computer or by the processor, comprising instructions that, when they are executed by the computer or the processor, prompt same to implement a method for the automated management of longitudinal speed according to one embodiment of the invention.

With reference toFIG.2, it is assumed that the ego vehicle10is traveling on a roadway containing at least two traffic lanes in the same direction. In the example illustrated inFIG.2, the ego vehicle10is positioned in the central lane40of a three-lane road. Two traffic lanes41,42are therefore adjacent to the central lane40and are located on either side thereof.

With reference toFIG.2, a definition is given of the terminology used in the rest of the document:The axis called the longitudinal axis101of the ego vehicle is defined as being an axis of symmetry of the ego vehicle parallel to the axis along which the vehicle moves in a straight line, oriented ahead of the vehicle.The axis called the lateral axis102of the ego vehicle perpendicularly intersects the longitudinal axis101at a point situated at the center of gravity of the ego vehicle, and it is oriented to the left of the ego vehicle, the left and the right being defined according to the viewpoint of the driver.The speed vector103of the ego vehicle in a projection onto the longitudinal axis101defines the longitudinal component104of the speed vector, called longitudinal speed.The speed vector103of the ego vehicle in a projection onto the lateral axis102defines the lateral component105of the speed vector, called lateral speed.Likewise, a distance between two vehicles may be projected onto the longitudinal and lateral axes, thus defining a longitudinal distance and a lateral distance.By convention, a vehicle will be considered to be situated ahead of the ego vehicle if it is located at least partially (for example to at least 50%) in the hemispace delimited by an axis106parallel to the lateral axis102and passing through the front end of the front bumpers of the ego vehicle and oriented in the direction of the axis101. This hemispace therefore corresponds to an area107called traffic area situated ahead of the ego vehicle.The traffic lane of the ego vehicle40is called main lane.The traffic lanes41and42adjacent to the main lane and situated on either side of this lane are called adjacent lanes.

The same terminology is applied to define the position parameters and speed parameters of a second vehicle20, shown inFIG.2. This second vehicle20is characterized by the fact that it is situated in the traffic around the ego vehicle, more particularly that it is traveling in an adjacent lane41,42and that its trajectory parameters (including position and speed) are taken into consideration when computing the setpoint longitudinal speed of the ego vehicle. In the rest of the document, this second vehicle20may also be referred to using the term target vehicle20.

A target vehicle may be a motor vehicle of any type, in particular a leisure vehicle or a utility vehicle or even a motorcycle.

The position parameters and speed parameters of the target vehicle20are defined as follows, with reference toFIG.2:The axis called the longitudinal axis201of the target vehicle20is defined as being its axis of longitudinal symmetry, oriented ahead of the vehicle.The axis called the lateral axis202of the target vehicle20perpendicularly intersects the longitudinal axis201at a point situated at the center of gravity of the target vehicle, and it is oriented to the left of the target vehicle.The speed vector203of the target vehicle20in a projection onto the longitudinal axis201defines the longitudinal component204of the speed vector, called longitudinal speed.The speed vector203of the target vehicle20in a projection onto the lateral axis202defines the lateral component205of the speed vector, called lateral speed.

In the rest of the document, “cut-in maneuver” denotes a driving sequence allowing a target vehicle20,50traveling in an adjacent lane41,42to cut in ahead of the ego vehicle, into the traffic in the main driving lane40.

In the rest of the document, “traffic corridor of the ego vehicle” denotes an area of the traffic lane of the ego vehicle that is delimited laterally by two notional lines parallel to the longitudinal axis of the ego vehicle, these two lines being equidistant from the longitudinal axis of the ego vehicle. In one embodiment, the traffic corridor may be defined as the longitudinal projection of the ego vehicle onto its traffic lane. In this embodiment, the width of the traffic corridor therefore corresponds to the width of the ego vehicle. In one alternative embodiment, the width of the traffic corridor of the ego vehicle could be different from the width of the ego vehicle, preferably greater than said width of the ego vehicle. In this embodiment, the width of the traffic corridor may for example define a margin of 30 cm on either side of the ego vehicle.

FIG.3shows the key times of a cut-in maneuver for a target vehicle20into the lane of the ego vehicle10:At the time T0, the target vehicle20overtakes the ego vehicle10. Its speed is then purely longitudinal. Its intention to perform a cut-in maneuver is therefore not able to be detected through its driving parameters: its lateral speed and its lateral acceleration are very small and its trajectory remains centered on its traffic lane42. At this stage, the target vehicle20may signal its intention to perform a cut-in maneuver, for example using visual indicators (flashing lights).At the time T1, the target vehicle20has a nonzero lateral speed205and possibly a nonzero lateral acceleration. It has therefore moved toward the demarcation line420situated between the lane of the ego vehicle and that of the target vehicle. At this stage, the driving parameters of the target vehicle20allow the ego vehicle to detect an intention of the target vehicle20to perform a cut-in maneuver into the lane of the ego vehicle.At the time T2, the target vehicle20crosses the demarcation line that separates its lane from that of the ego vehicle.At the time T2b, the target vehicle20penetrates into a traffic corridor110centered on the longitudinal axis of the ego vehicle10.At the time T3, the target vehicle20is situated entirely in the traffic lane of the ego vehicle.

The criterion establishing line crossing by a vehicle may be defined as being the crossing of this line by at least one point of the following parts of the vehicle:the lateral edge of the chassis of the vehicle, this lateral edge being closest to the ego vehicle, orthe lateral edge of at least one of the wheels of this vehicle, orthe center of gravity of this vehicle.

As an alternative, the criterion establishing line crossing by a vehicle may be defined as being the crossing of this line by the whole vehicle.

Preferably, the crossing criterion is defined as being the crossing of this line by at least one point of a lateral edge of the chassis of this vehicle.

In the rest of the document, the expression “end of the cut-in maneuver” may denote the time T3starting from which the target vehicle20is situated entirely in the traffic lane of the ego vehicle. Preferably, the end of the cut-in maneuver may be seen as the time T2bat which the target vehicle20penetrates into a traffic corridor centered on the longitudinal axis of the ego vehicle. According to another variant embodiment, the end of the cut-in maneuver could also be seen as the time T2of crossing the demarcation line.

A first mode of execution of a method for the automated management of longitudinal speed is described below with reference toFIG.3. The management method may also be seen as being a method for operating a management system or as a method for operating a motor vehicle equipped with a management system. This first mode of execution of the method comprises three steps E1, E2and E3, which will be described below.

In a first step E1, an intention of a target vehicle20, traveling in an adjacent lane41, to perform a cut-in maneuver into the main lane40is detected.

With reference toFIG.3described above, an intention to perform a cut-in maneuver may be detected between the time TO and the time T1. Indeed, as illustrated at the time TO, detecting an intention to perform a cut-in maneuver may involve detecting flashing lights even before the vehicle begins maneuvering, that is to say before the target vehicle20begins moving toward the demarcation line420situated between its traffic lane42and that of the ego vehicle40.

In addition or as an alternative, an intention to perform a cut-in maneuver may be detected at a time T1at which the target vehicle has initiated a lateral movement toward the demarcation line420. In this case, detecting an intention to perform a cut-in maneuver may involve trajectory parameters of the target vehicle20. In the case of vehicles traveling in rectilinear lanes, the start of the insertion maneuver is manifested by an increase in the lateral speed205and possibly in the lateral acceleration of the target vehicle20. The method may therefore utilize the data from the detection means3to compare the lateral speed and/or the lateral acceleration of the target vehicle20with minimum thresholds.

In addition or as an alternative, the method uses trajectory data of the target vehicle20to estimate a time to line crossing (TLC in acronym form), corresponding to the time at the end of which the target vehicle20will cross a limit situated between the ego vehicle and the target vehicle.

In one preferred embodiment, the TLC relates to the crossing of a lateral limit of a traffic corridor110centered on the longitudinal axis of the ego vehicle10. Calibrating the width of this corridor makes it possible to refine the estimate of the time at which the trajectory of the target vehicle20will effectively intersect that of the ego vehicle.

Preferably, the width of the corridor110is therefore greater than the width of the ego vehicle and less than the width of a highway traffic lane.

On the basis of one or the other of the options for computing a TLC time, the method detects an intention to perform a cut-in maneuver by comparing the TLC time with a maximum threshold, for example 1.5 seconds.

In one variant implementation, the method combines the conditions presented above in order to detect an intention to perform a cut-in maneuver.

According to another variant, an intention to perform a cut-in maneuver could be detected by way of an inter-vehicle communication device and/or by way of a device for communication with a remote server and/or by way of a geolocation device.

At a given time, the method detects an intention to perform a cut-in maneuver and moves to a second step E2of estimating a corrected longitudinal distance DLCOR.

The corrected longitudinal distance DLCOR corresponds to an estimate of the longitudinal distance that will separate the ego vehicle10from the target vehicle20at the end of the cut-in maneuver.

For example, with reference toFIG.3, the time of detection of an intention to perform a cut-in maneuver is T1. At the time T1, a corrected longitudinal distance DLCOR1is estimated, the significance of which depends on the criterion chosen to compute the TLC:if the TLC is computed using a criterion regarding crossing of the demarcation line between the lanes40and42, then TLC=T2and DLCOR1will be an estimate of the distance DLMES2that will separate the ego vehicle10from the target vehicle20at the time T2:if the TLC is computed using a criterion regarding the target vehicle20penetrating into a traffic corridor centered on the longitudinal axis of the ego vehicle, then TLC=T2band DLCOR1will be an estimate of the distance DLMES2bthat will separate the ego vehicle10from the target vehicle20at the time T2b,if the TLC is computed as being the time at which the target vehicle20is situated entirely in the traffic lane of the ego vehicle, then TLC=T3and DLCOR1will be an estimate of the distance DLMES3that will separate the ego vehicle10from the target vehicle20at the time T3.

At a time t, the corrected longitudinal distance may be estimated from the driving parameters of the ego vehicle10and of the target vehicle20, these parameters being measured at the time t.

The method thus computes a corrected longitudinal distance DLCOR(t) using the formula

where:DLMES(t) is the longitudinal distance measured at the time t between the ego vehicle10and the target vehicle20,VLR(t) is the relative longitudinal speed measured at the time t between the ego vehicle10and the target vehicle20, andTLC(t) is an estimate at the time t of the time to line crossing.

The relative longitudinal speed VLR(t) measured between the ego vehicle10and the target vehicle20may be positive or negative. Thus, to avoid obtaining a negative value when computing the corrected longitudinal distance DLCOR, the function “maximum ( )” is used to bound the result of this computation to the minimum value of 0.

A corrected longitudinal distance DLCOR(t) is thus computed in real time in order to be transmitted to a third step E3of computing a longitudinal speed setpoint VLC, applicable at the time t.

At each time t, a corrected longitudinal distance DLCOR(t) is computed depending on the relative longitudinal speed VLR(t). The corrected longitudinal distance DLCOR(t) thus computed may vary over time if the relative longitudinal speed between the first and the second vehicle varies. This thus gives an estimate of the corrected longitudinal distance DLCOR(t) that will be all the more precise the more the relative longitudinal speed VLR(t) remains substantially constant beyond the time t. According to one variant embodiment of the invention, the corrected longitudinal distance DLCOR(t) could also be computed based on an acceleration of the first vehicle and/or of the second vehicle, measured or computed at the time t. Such accelerations could be integrated over a period of time equal to the time TLC(t). The computation of the corrected longitudinal distance DLCOR(t) could thus be more complex but also more precise.

In one embodiment of step E3, the longitudinal speed setpoint VLC may be computed so as to establish and maintain a reference longitudinal distance DLR between the ego vehicle10and the target20. In other words, based on the corrected longitudinal distance DLCOR, computed in step E2, the method computes the longitudinal speed setpoint VLC that the ego vehicle10should apply in order for the longitudinal distance measured between the ego vehicle10and the target vehicle20to be equal to the reference longitudinal distance DLR.

In this embodiment, the reference longitudinal distance may be computed in step E3based on the corrected longitudinal distance DLCOR and on the driving parameters of the ego vehicle10and of the target vehicle20. Advantageously, the driving parameters include the longitudinal speed of the target vehicle.

FIG.6illustrates the sequence of the method and the evolution of the corrected longitudinal distance during a cut-in maneuver of the target vehicle20into the lane of the ego vehicle10, in the case where the relative longitudinal speed VLR of the target vehicle20with respect to the ego vehicle10is strictly positive. In other words, the target vehicle20moves away from the ego vehicle10in the course of the cut-in maneuver.

In the example shown, the relative longitudinal speed VLR measured at t=0 s is 10 meters per second.

At t=0 s,In step E1, a target vehicle20having an intention to perform a cut-in maneuver into the lane of the ego vehicle10is detected.The two vehicles are traveling in two separate lanes and the longitudinal distance DLMES01measured between the target vehicle20and the ego vehicle10is 5 meters.In step E2, the time to crossing TLC is estimated. In the example ofFIG.6, the time to crossing TLC is estimated at 1.5 s.In step E2, a corrected longitudinal distance is computed, DLCOR01=5+10×1.5=20 meters.In step E3, the corrected longitudinal distance is taken into consideration in order to compute a setpoint longitudinal speed VLC01for establishing a reference longitudinal distance between the two vehicles. InFIG.6, it is assumed that the reference longitudinal distance DLR01computed at the time t=0 s is equal to 25 meters in order to illustrate the effect of the invention. With this implementation of the method, the regulation of the longitudinal speed of the ego vehicle10at t=0 will be calibrated based on the difference ΔDLCOR01between the corrected longitudinal distance DLCOR01and the reference longitudinal distance DLR01. In other words, the regulation of the longitudinal speed of the ego vehicle10will be calibrated in order to change the corrected longitudinal distance DLCOR from 20 meters to 25 meters between the times t=0 and t=TLC=1.5 s, this corresponding to a moderate deceleration. Without implementing the method, at t=0 s, the regulation of the longitudinal speed of the ego vehicle10would have been calibrated based on the difference ΔDLMES01between the measured longitudinal distance DLMES01and the reference longitudinal distance DLR01. In other words, the regulation of the longitudinal speed of the ego vehicle10would have been calibrated so as to change the measured longitudinal distance DLMES from 5 meters to 25 meters between the times t=0 and t=TLC=1.5 s, this corresponding to a strong deceleration.

Thus, in the case where the target vehicle20moves away from the ego vehicle10during the cut-in maneuver, implementing the method makes it possible to avoid sudden movements linked to the longitudinal regulation with respect to a target at the start of a cut-in maneuver. Implementing the method therefore makes it possible to improve driving comfort.

FIG.7illustrates the sequence of the method and the evolution of the corrected longitudinal distance during a cut-in maneuver of the target vehicle20into the lane of the ego vehicle10, in the case where the relative longitudinal speed VLR of the target vehicle20with respect to the ego vehicle10is strictly negative. In other words, the target vehicle20moves toward the ego vehicle10during the cut-in maneuver.

In the example shown, the relative longitudinal speed VLR measured at t=0 s is −5 meters per second.

At t=0 s,In step E1, a target vehicle20having an intention to perform a cut-in maneuver into the lane of the ego vehicle10is detected.The two vehicles are traveling in two separate lanes and the longitudinal distance DLMES02measured between the target vehicle20and the ego vehicle10is 20 meters.In step E2, the method estimates the time to crossing TLC. In the example ofFIG.7, said time to crossing TLC is estimated at 1.5 seconds.In step E2, a corrected longitudinal distance is computed, DLCOR02=20+(−5)×1.5=12.5 meters.In step E3, the corrected longitudinal distance DLCOR02is taken into consideration in order to compute a setpoint longitudinal speed VLC for establishing a reference longitudinal distance between the two vehicles. InFIG.7, it is assumed that the reference longitudinal distance DLR02computed at the time t=0 s is equal to 25 meters in order to illustrate the effect of the invention. With the implementation of the method, the regulation of the longitudinal speed of the ego vehicle10at t=0 will be calibrated based on the difference ΔDLCOR02between the corrected longitudinal distance DLCOR02and the reference longitudinal distance DLR02. In other words, the regulation of the longitudinal speed of the ego vehicle10will be calibrated so as to change the corrected longitudinal distance DLCOR from 12.5 meters to 25 meters between the times t=0 and t=TLC=1.5 s, this corresponding to a strong deceleration. Without implementing the method, at t=0 s, the regulation of the longitudinal speed of the ego vehicle10would have been calibrated based on the difference ΔDLMES02between the measured longitudinal distance DLMES02and the reference longitudinal distance DLR02. In other words, the regulation of the longitudinal speed of the ego vehicle10would have been calibrated so as to change the measured longitudinal distance DLMES from 20 meters to 25 meters between the times t=0 and t=TLC=1.5 s, this corresponding to an excessively weak deceleration, or even a lack of deceleration to anticipate the approach of the target vehicle. This excessively small deceleration would therefore have to have been followed by a sharp deceleration in order to avoid a collision with the target vehicle.

In the case described byFIG.7, the cut-in maneuver may be dangerous. The role of the method is here to improve the safety of the vehicle, that is to say to slow the ego vehicle down early and strongly in order to anticipate the approach of the target vehicle.

It is therefore understood that the method may comprise a step of comparing the speed of the ego vehicle and the speed of the second vehicle. The longitudinal speed setpoint computed in the third step E3is a weak deceleration setpoint if the speed of the second vehicle is strictly greater than the speed of the ego vehicle. The longitudinal speed setpoint is a strong deceleration setpoint if the speed of the second vehicle is strictly less than the speed of the ego vehicle. The amplitude (or absolute value) of the weak acceleration is strictly less than the amplitude of the strong deceleration.

A second mode of execution of a method for the automated management of longitudinal speed is described below with reference toFIG.4. This second mode of execution of the method comprises four steps E0, E4, E5and E6.

This mode of execution relates to the implementation of the method for the automated management of longitudinal speed in a context of multi-target longitudinal guidance. In particular, this mode of execution describes the implementation of the method in a traffic configuration shown inFIG.8.

The traffic configuration shown inFIG.8is such that:the ego vehicle10, or first vehicle, is positioned in the central lane40of a three-lane highway,a second vehicle20is traveling in an adjacent lane41,42,a third vehicle30is traveling in the lane of the ego vehicle and ahead thereof,the second vehicle20performs a cut-in maneuver into the central lane, between the ego vehicle and the third vehicle30.

Step E0consists of three sub-steps, E1, E2and E3. The sub-steps E1, E2and E3of the second mode of execution are respectively similar to steps E1, E2and E3described above for the first mode of execution.

During step E0, the method therefore detects the cut-in maneuver of the second vehicle20and computes a first reference longitudinal speed based on a computation of a corrected longitudinal distance between the ego vehicle10and the second vehicle20.

In parallel with the sequence of step E0, in a step E4, the method detects a third vehicle30.

In a step E5, the method computes a second reference longitudinal speed of the ego vehicle based on the speed of the third vehicle30.

The first and second reference longitudinal speeds are then processed in a step E6.

In step E6, the method computes the longitudinal speed setpoint for the ego vehicle for maintaining a given minimum longitudinal distance between the ego vehicle10and the second and third vehicle20,30.

The longitudinal speed setpoint for the ego vehicle will be computed by selecting the minimum longitudinal speed from among the first and second reference longitudinal speeds computed in steps E0and E5.

The method is thereby in a configuration with guidance with respect to the target having the most constrictive reference longitudinal speed.