METHOD AND DEVICE FOR CONTROLLING THE ACCELERATION OF A VEHICLE

Description

technical field

[0001] The invention relates to methods and devices for controlling the acceleration of a vehicle, in particular a motor vehicle. The invention also relates to a method and device for controlling a vehicle, in particular for controlling an adaptive cruise control system of a vehicle. Technological background

[0002] Some contemporary vehicles are equipped with functions or systems or driver assistance systems, known as ADAS (from the English "Advanced Driver-Assistance System" or in French "Système d'aide à la conduite avancé").

[0003] Among these systems, the adaptive cruise control system, or ACC, has as its primary function the automatic and adaptive regulation of the speed of equipped vehicles according to their environment. Such an ACC system determines one or more acceleration commands based on a speed setting and information relating to the vehicle's surroundings; the acceleration command(s) are specifically designed to regulate the vehicle's speed adaptively, that is, by taking the vehicle's environment into account.

[0004] This environmental information includes, for example, the distance between the vehicle equipped with the ACC system and a vehicle traveling ahead, the speed (e.g., relative speed) of the vehicle in front, the acceleration (or deceleration) of the vehicle in front, and / or a regulatory speed limit. Such a vehicle traveling ahead is called the target vehicle or target object of the ACC system. The acceleration command(s) are determined, for example, from a control law based on estimates of the torque supplied by a powertrain (e.g., an internal combustion or electric motor) to one or more wheels of the vehicle and the vehicle's current acceleration.

[0005] A vehicle's environmental information is obtained, for example, from sensors onboard the vehicle, such as radar. This information is particularly important for a vehicle, for example, to improve vehicle safety by taking into account the surrounding environment, including other vehicles.

[0006] When the vehicle equipped with ACC loses sight of the target vehicle, for example, due to a malfunction of the onboard sensors or when the target vehicle's trajectory changes, the acceleration of the vehicle whose speed is regulated by the ACC system may be significant, even abrupt. This can cause discomfort for passengers, and even lead to an accident if the target vehicle is still ahead of the vehicle equipped with ACC.

[0007] In addition, the prior art is known from documents US2018237011A1 and US2010250087A1. Summary of the invention

[0008] One object of the present invention is to solve at least one of the problems of the technological background described above.

[0009] Another object of the present invention is to improve the operation of an ACC system of a vehicle.

[0010] According to a first aspect, the invention relates to a method for controlling the acceleration of a first vehicle, the first vehicle comprising an adaptive speed control system, known as the ACC system, the method comprising the following steps subsequent to the deselection of a second vehicle as the target vehicle of the ACC system: a) determination of a representative value of a current acceleration variation, called current jolt value, as a function of a current speed of the first vehicle and an acceleration value, called previous acceleration value, obtained from the ACC system at a time before the current time; b) determination of a current acceleration value of the ACC system as a function of the current jolt value and the previous acceleration value; c) acceleration control of the first vehicle as a function of the current acceleration value.

[0011] This process filters or adjusts the acceleration calculated by the ACC system based on a vibration value that depends, among other things, on the speed of the first vehicle. The function relating the vibration value to the speed of the first vehicle determines a vibration value that attenuates the acceleration of the first vehicle. This attenuation is particularly useful when the target vehicle of the ACC system is lost or deselected, for example, in the event of a sensor malfunction on the first vehicle, a problem analyzing environmental data by the ACC system, or a change in trajectory of the vehicle that previously corresponded to the target vehicle.

[0012] According to one variant, the current shock value corresponds to: a first value of shock when the previous acceleration value is strictly less than 0, the first value of shock being according to a first function of the speed of the first vehicle; or a second value of shock when the previous acceleration value is greater than or equal to 0, the second value of shock being according to a second function of the speed of the first vehicle.

[0013] According to another variant, the first shock value is: equal to a first minimum shock value for any speed of the first vehicle between 0 and a first minimum speed, following an increasing function of the speed of the first vehicle when the speed of the first vehicle is between the first minimum speed and a first maximum speed of the first vehicle, the first maximum speed being greater than the first minimum speed, and equal to a first maximum shock value for any speed of the first vehicle greater than the first maximum speed; and the second shock value is: equal to a second minimum shock value for any first vehicle speed between 0 and a second minimum speed, the second minimum shock value being less than the first minimum shock value, following an increasing function of the first vehicle speed when the first vehicle speed is between the second minimum speed and a second maximum first vehicle speed, the second maximum speed being greater than the second minimum speed, and equal to a second maximum shock value for any first vehicle speed greater than the second maximum speed, the second maximum shock value being less than the first maximum shock value.

[0014] According to a further variant, the current acceleration value of the ACC system is: A t = A t − dt + J V * dt , with A(t) the current acceleration value, A(t-dt) the previous acceleration value, dt the time interval separating the previous instant and the current instant, J(V) the value of the jolt as a function of the speed V of the first vehicle.

[0015] According to yet another variant, steps a), b) and c) are repeated for a determined duration from a time instant corresponding to the deselection of the second vehicle.

[0016] According to an additional variant, the determined duration is equal to 2 seconds.

[0017] According to a second aspect, the invention relates to a vehicle acceleration control device, the device comprising a memory associated with a processor configured for the implementation of the steps of the process according to the first aspect of the invention.

[0018] According to a third aspect, the invention relates to a vehicle, for example of the automobile type, comprising the device as described above according to the second aspect of the invention.

[0019] According to a fourth aspect, the invention relates to a computer program which includes instructions adapted for carrying out the steps of the process according to the first aspect of the invention, in particular when the computer program is executed by at least one processor.

[0020] Such a computer program can use any programming language, and be in the form of source code, object code, or an intermediate form between source code and object code, such as in a partially compiled form, or in any other desirable form.

[0021] According to a fifth unclaimed aspect, the invention may relate to a computer-readable recording medium on which is recorded a computer program comprising instructions for carrying out the steps of the process according to the first aspect of the invention.

[0022] On the one hand, the recording medium can be any entity or device capable of storing the program. For example, the medium can include a storage means, such as a ROM, a CD-ROM or a microelectronic circuit-type ROM, or a magnetic recording means or a hard drive.

[0023] 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 transmitted via an electrical or optical cable, by conventional or radio frequency, by self-directing laser beam, or by other means. The computer program according to the invention can, in particular, be uploaded to a network such as the Internet.

[0024] 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 the execution of the process in question. Brief description of the figures

[0025] Other features and advantages of the invention will become apparent from the description of the non-limiting embodiments of the invention below, with reference to figures 1 to 5 attached, on which: [ Fig. 1] schematically illustrates a first vehicle and a second vehicle, according to a particular embodiment of the present invention; ] Fig. 2 ] illustrates functions representing the evolution of a shock value as a function of the speed of the first vehicle in the figure 1 , according to a particular embodiment of the present invention; [ Fig. 3 ] illustrates a diagram representing the evolution of acceleration over time as determined by an ACC system installed in the first vehicle of the figure 1 , according to a particular embodiment of the present invention; [ Fig. 4 ] schematically illustrates a device configured to control the acceleration of the first vehicle in the figure 1 , according to a particular embodiment of the present invention. [ Fig. 5 ] illustrates a flowchart of the different stages of a process for controlling the acceleration of the first vehicle of the figure 1, according to a particular embodiment of the present invention. Description of the implementation methods

[0026] A method and device for controlling the acceleration of a vehicle will now be described in what follows, with joint reference to figures 1 to 5 The same elements are identified with the same reference symbols throughout the description that follows.

[0027] According to a particular and non-limiting embodiment of the invention, a computer, for example the computer responsible for controlling the ACC system of a first vehicle, determines an acceleration value (corresponding to a potential acceleration value or a gross acceleration value) at a current instant as a function of a current jerk value. This jerk value is advantageously determined as a function of the current speed of the first vehicle and a previous acceleration value determined by the ACC system at an instant preceding the current instant, for example, as a function of the sign, positive or negative, of the previous acceleration value. The acceleration of the first vehicle is then controlled according to the determined current acceleration value.

[0028] A shock value advantageously corresponds to a quantity representing a variation of the acceleration over time, expressed in ms -3< .

[0029] This process filters or adjusts the acceleration calculated by the ACC system based on a vibration value that depends, among other things, on the speed of the first vehicle. The function relating the vibration value to the speed of the first vehicle determines a vibration value that attenuates the acceleration of the first vehicle. This attenuation is particularly useful when the target vehicle of the ACC system is lost or deselected, for example, in the event of a sensor malfunction on the first vehicle, a problem analyzing environmental data by the ACC system, or a change in trajectory of the vehicle that previously corresponded to the target vehicle.

[0030] Such an adjustment improves the safety of the first vehicle and the comfort of its passengers by attenuating acceleration based on a jolt value, particularly when the target vehicle has been deselected by mistake and is still in front of the first vehicle.

[0031] There figure 1 schematically illustrates a first vehicle 10 following a second vehicle 11 on a section of road in an environment 1, according to a particular and non-limiting embodiment of the present invention.

[0032] There figure 1 illustrates a first vehicle 10, for example a motor vehicle, carrying one or more sensors configured to detect the presence of objects in the environment 1 of the first vehicle 10. According to other examples, the first vehicle 10 corresponds to a coach, a bus, a truck, a utility vehicle or a motorcycle, that is to say a motorized land vehicle type vehicle.

[0033] The first vehicle, 10, corresponds to a vehicle operating under the full supervision of a driver or operating in an autonomous or semi-autonomous mode. The first vehicle operates according to an autonomy level of 0 or according to an autonomy level ranging from 1 to 5, for example, according to the scale defined by the American federal agency which has established 5 levels of autonomy from 1 to 5, level 0 corresponding to a vehicle with no autonomy, whose driving is under the full supervision of the driver, level 1 corresponding to a vehicle with a minimal 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 fully autonomous vehicle.

[0034] Following the example of the figure 1The first vehicle 10 travels on a two-lane section of road, 1001, 1002. For example, the first vehicle 10 travels in the right-hand lane 1001, with both lanes 1001 and 1002 traveling in the same direction. Alternatively, lane 1001 travels in one direction and lane 1002 in the opposite direction.

[0035] Following the example of the figure 1 , the first vehicle 10 follows a second vehicle 11, at a determined distance which may vary over time (depending on the dynamic behavior of the first vehicle 10 and the second vehicle 11), the second vehicle 11 traveling on the same traffic lane 1001 as the first vehicle 10 and in the same direction as the first vehicle 10.

[0036] The second vehicle 11 corresponds to the target object (also called the target vehicle) selected by the ACC system of the first vehicle 10, at least for a certain period of time until the second vehicle is deselected as the target vehicle of the ACC system. Deselection is implemented, for example, by the ACC system when the sensors of the first vehicle 10 no longer detect the presence of the second vehicle 11 or when the ACC system misinterprets the data received from these sensors.

[0037] The first vehicle 10, for example, carries one or more of the following sensors: one or more millimeter-wave radars arranged on the first 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 reflected by one or more objects (for example the second vehicle 11 located in front of the first vehicle 10 according to the example of the figure 1), in order to detect obstacles and their distances from the first vehicle 10; and / or one or more LIDAR(s) (from the English "Light Detection And Ranging", or "Detection and estimation of distance by light" in French), a LIDAR sensor corresponding to an optoelectronic system composed of a laser emitting device, a receiving device including a light collector (to collect the part of the light radiation emitted by the emitter and reflected by any object located in the path of the light rays emitted by the emitter) and a photodetector which transforms the collected light into an electrical signal; a LIDAR sensor thus makes it possible to detect the presence of objects (for example the second vehicle 11) located in the emitted light beam and to measure the distance between the sensor and each detected object;and / or one or more cameras (with or without a depth sensor) for acquiring one or more images of the environment around the first vehicle 10 located in the field of vision of the camera(s).

[0038] The data obtained from this sensor or these sensors varies depending on the type of sensor. In the case of radar or LiDAR, the data corresponds, for example, to distance data between points on the detected object and the sensor. Each detected object is thus represented by a point cloud (each point corresponding to a point on the object receiving the radiation emitted by the sensor and reflecting at least part of this radiation). The point cloud represents the envelope (or part of the envelope) of the detected object as seen by the sensor and ultimately by the vehicle carrying the sensor. In the case of a video camera, the data corresponds to data associated with each pixel of the acquired image(s), for example, grayscale values ​​coded on, for example, 8, 10, 12 or more bits for each color channel, for example RGB (Red, Green, Blue).This data allows, for example, the determination of the successive positions taken by an object moving within environment 1, such as the second vehicle 11, and the deduction of one or more dynamic parameters of the moving object, such as its speed and / or acceleration. This data also allows the determination of lane markings on the ground, for example, to help determine whether the second vehicle 11 and the first vehicle 10 belong to the same traffic lane.

[0039] The data acquired by the on-board sensor(s) feeds, for example, one or more driver assistance systems, known as ADAS (Advanced Driver-Assistance System), on-board in the first vehicle 10. Such an ADAS system is configured to assist, or even replace, the driver of the first vehicle 10 in controlling the first vehicle 10 on its journey.

[0040] The first vehicle 10 advantageously carries an ADAS system corresponding to an automatic speed regulation system, known as ACC. When the ACC system is activated, the ACC system aims to achieve a setpoint acceleration, denoted A(t) (also called gross setpoint acceleration or potential acceleration), which varies over time 't' and which allows maintaining a determined safety distance from the second vehicle 11 ahead of the first vehicle 10, i.e. a target vehicle traveling in front of the first vehicle 10 in the same direction of travel on the same lane of travel as long as this second vehicle 11 is detected by the sensors on board the first vehicle 10.

[0041] As long as the second vehicle 11 is selected as the target vehicle of the ACC system, an acceleration value (setpoint, raw setpoint, or potential) is determined, for example, at a current instant 't' by the ACC system from a set of data obtained from one or more object detection sensors on board the first vehicle 10 and / or dynamic parameters of the first vehicle 10. The target acceleration value (expressed in ms⁻²) is, for example, calculated from: representative data of the dynamic behavior of the second vehicle 11 (e.g. speed and / or acceleration), this data being obtained for example from a set of positions taken by the second vehicle 11 over a time interval preceding the current instant 't' for which the target acceleration is determined.The data on the positions taken by the second vehicle 11 are advantageously determined from the data received from the object detection sensor(s) on board the first vehicle 10; data representative of the dynamic behavior of the first vehicle 10 (for example speed, acceleration, distance from the second vehicle 11), this data being obtained from sensors on board the first vehicle 10, the distance being obtained for example from the data received from the object detection sensor(s); and / or setpoint parameters provided to the ACC system, such as for example a target inter-vehicle distance or time (IVD or IVT), these parameters being stored in memory or entered by a user via a Human-Machine Interface, known as an HMI.

[0042] A process for controlling the acceleration of a vehicle, for example the first vehicle 10 equipped with the ACC system, is advantageously implemented by the vehicle 10 itself, i.e., by a computer or a combination of computers of the vehicle 10's onboard system, for example, by the computer(s) responsible for controlling the ACC system. To this end, one or more acceleration values ​​(potential or raw setpoint) are determined via the operations or steps described below.

[0043] Such a process is advantageously implemented or initiated when the second vehicle 11 is lost as the target vehicle of the ACC system of the first vehicle 10, that is, when the ACC system deselects the second vehicle 11 as the target vehicle, for whatever reason (end of detection of the second vehicle 11 by the sensors of the first vehicle 10 or problem analyzing the data from these sensors for example).

[0044] In a first operation, a representative value of a current acceleration variation, called the current shock value, is determined or calculated as a function of a current speed V(t) of the first vehicle 10 and an acceleration value, called the previous acceleration value A(t-dt), obtained from the ACC system at a time 't-dt' preceding the current time 't'.

[0045] The value of the shock at time 't' is advantageously determined according to one or more functions of the speed of the first vehicle 10. The function relating the value of the shock to the speed of the first vehicle advantageously corresponds to a monotonically increasing function.

[0046] When the previous acceleration value A(t-dt) is strictly less than 0 (of negative sign with A(t-dt)<0), the value of the jolt is according to a first (increasing monotonic) function, denoted J1(V), of the speed V of the first vehicle 10.

[0047] When the previous acceleration value A(t-dt) is greater than or equal to 0 (of positive sign with A(t-dt)≥0), the value of the jolt is according to a second (increasing monotonic) function, denoted J2(V) of the velocity V of the first vehicle 10.

[0048] There figure 2 illustrates an example of a first function 21 and a second function 22 between the value of the shock (noted J on the ordinate of diagram 2) and the speed of the first vehicle 10 (noted V on the abscissa of diagram 2).

[0049] Following the example of the figure 2 The first function 21 includes: a first part for which the value of the shock (called first value of the shock) corresponds to a constant and is equal to a first minimum value of the shock, denoted J1 min, for any speed V of the first vehicle 10 between 0 km / h and a first minimum speed, denoted V1 min; a second part for which the first value of the shock increases as the speed V of the first vehicle increases, the first value of the shock increasing for example according to a linear function to go from the first minimum value of the shock J1 min to a first maximum value of the shock, denoted J1 max, (J1 max > J1 min) for a speed V between the first minimum speed V1 min and a first maximum speed, denoted V1 max, with V1 max > V1 min;and a third part for which the first shock value corresponds to a constant and is equal to the first maximum shock value J1 max for any speed V of the first vehicle 10 greater than the first maximum speed V1 max. ;

[0050] Following the example of the figure 2 The second function 22 includes: a first part for which the shock value (called the second shock value) corresponds to a constant and is equal to a second minimum shock value, denoted J2 min, for any speed V of the first vehicle 10 between 0 km / h and a second minimum speed, denoted V2 min; V2 min is for example greater than V1 min; a second part for which the second shock value increases as the speed V of the first vehicle increases, the second shock value increasing for example according to a linear function to go from the second minimum shock value J2 min to a second maximum shock value, denoted J2 max, (J2 max > J2 min) for a speed V between the second minimum speed V2 min and a second maximum speed, denoted V2 max, with V2 max > V2 min; V2 max is for example greater than V1 max;and a third part for which the second shock value corresponds to a constant and is equal to the second maximum shock value J2 max for any speed V of the first vehicle 10 greater than the second maximum speed V2 max. ;

[0051] The value of J1 max is, for example, greater than the value of J2 max and the value of J1 min is, for example, greater than the value of J2 min.

[0052] The parameters J1 min, J1 max, J2 min, J2 max, V1 min, V1 max, V2 min and V2 max are adjustable or calibrable to adapt to the type of ACC system (e.g. silhouette, type of actuators, type of sensors), the type of the first vehicle and / or the profile or expectations of the driver of the first vehicle.

[0053] As a purely illustrative example, J1 min = 1 ms -3< ; J1 max = 2 ms -3< ; J2 min = 0.5 ms -3< ; J2 max = 1.5 ms -3< ; V1 min = 3 ms -1< ; V1 max = 30 ms -1< ; V2 min = 5 ms -1< ; V2 max = 50 ms -1< .

[0054] Following the example of the figure 2 , the variation in acceleration allowed by the first function 21 is thus greater than the variation in acceleration allowed by the second function 22.

[0055] In a second operation, a current acceleration value (at the current time 't') of the ACC system is determined as a function of the current jolt value obtained in the first operation as a function of the current speed of the first vehicle, according to the first function 21 or the second function 22, that is to say according to the positive or negative sign of the acceleration determined by the ACC system at the previous time 't-dt'.

[0056] The ACC system, for example, determines an acceleration value at regular intervals, with a duration equal to dt, for example, equal to 50 ms. In other examples, dt is equal to 10, 20, 30 or 40 ms, or any value between 10 and 50 ms.

[0057] The acceleration value A(t) of the ACC system, that is to say determined by the ACC system and supplied at the output of the ACC system at a time 't', is obtained via the following equation 1: A t = A t − dt + J V * dt

[0058] With A(t-dt) corresponding to the acceleration value obtained by the ACC system at the time 't-dt' preceding the time 't' according to the time step 'dt', J(V) corresponding to the value of the jolt obtained as a function of the speed V of the first vehicle 10 according to the first function 21 (J(V) then being equal to J1(V) and corresponding to the first value of jolt) or according to the second function 22 (J(V) then being equal to J2(V) and corresponding to the second value of jolt) and 'dt' corresponding to the time step or the time interval between two successive determinations (from a time perspective) of the acceleration by the ACC system.

[0059] When the process begins, that is, when the ACC system of the first vehicle 10 loses the second vehicle 11 and deselects it so that the second vehicle 11 is no longer the target vehicle, the first value of A(t) is calculated at t deselect +dt, where t deselect corresponds to the time of deselecting the second vehicle 11 as the target vehicle, via equation 1, taking A(t-dt) to be equal to the last acceleration value determined by the ACC system based on the second vehicle 11 as the target vehicle, that is, from the difference in speed between the first vehicle 10 and the second vehicle 11 and from the distance separating the first vehicle 10 from the second vehicle 11. Subsequent values ​​of the acceleration A(t) are determined from the previous acceleration value determined via equation 1.

[0060] There figure 3illustrates a diagram 3 representing an acceleration profile (noted A on the ordinate of diagram 3) obtained at the output of the ACC system of the first vehicle 10 as a function of time (noted t on the abscissa of diagram 3), according to a particular and non-limiting embodiment of the present invention.

[0061] Following the example of the figure 3The acceleration profile includes a first part 31 where the acceleration is negative (corresponding to deceleration) and decreases until it reaches a minimum (or maximum deceleration). This first part corresponds to a time period 310 during which the ACC system is based on the second vehicle 11 (which corresponds to the target vehicle of the ACC system) located in front of the first vehicle 10. According to this example, the second vehicle 11 is in a deceleration phase, which results in negative acceleration values, determined by the ACC system, to maintain, for example, a specific inter-vehicle distance. The moment when the ACC system loses the second vehicle as the target object is represented by a point 311 on the figure 3 , the associated deselection instant of the second vehicle corresponding to deselection t, with for example an associated acceleration value determined by the ACC system as a function of the second vehicle 11.

[0062] The acceleration profile illustrated on the figure 3 It also includes a second part 32 and a third part 33 extending over a time period 320. The duration of the time period 320 corresponds, for example, to a parameter of the ACC system and may have an adjustable duration (e.g., by the driver) or a fixed duration stored in the ACC system's memory. The duration of the time period 320 is, for example, equal to 2 seconds, this time period starting at the moment of deselection t deselection 311. According to other examples, the duration of the time period 320 is equal to 1, 1.5, 2.5, 3, or 4 seconds.

[0063] The second part 32 follows temporally from the first part 31, the values ​​of the acceleration A forming this second part being determined by the ACC system via equation 1 as a function of the first value of shock J1(V) since the acceleration values ​​are strictly less than 0 ms -2< .

[0064] When the acceleration value reaches 0 ms⁻², the third part 33 of the profile begins with a profile different from that of the second part 32. The third part 33 follows temporally from the second part 32, the acceleration values ​​A forming this second part being determined by the ACC system via equation 1 as a function of the second shock value J2(V), since the acceleration values ​​are greater than or equal to 0 ms⁻². The profile of the third part 33 differs from that of the second part 32 in that the change in acceleration between two successive acceleration values ​​is less significant than it is for two successive acceleration values ​​in the second part 32.This is explained by the profile of the second function 22 (of the second shock value) which is different from that of the first function 21 (of the first shock value), the minimum and maximum values ​​of the second function 22 being lower than the minimum and maximum values, respectively, of the first function 21.

[0065] The acceleration determined by the ACC system following the loss of the target vehicle is smoother and with a lower maximum acceleration than would be obtained with a prior art ACC system not based on jolt values ​​determined as a function of the speed of the first vehicle 10, as described above.

[0066] Filtering the acceleration value with a jolt value that is a function of the speed of the first vehicle 10 limits the variation in acceleration, resulting in a less abrupt acceleration and therefore greater comfort for passengers. Furthermore, if the deselection of the second vehicle 11 was erroneous (for example, due to a problem with the sensors of the first vehicle 10), limiting the acceleration reduces the risk of collision with the second vehicle 11, which remains positioned in front of the first vehicle 10.

[0067] Of course, the acceleration profile illustrated on the figure 3 corresponds to a particular example, the invention not being limited to such an example. For example, the first part 31 could correspond to a phase of positive acceleration, followed by a single second phase extending over the entire time period 320 and determined from equation 1 as a function of the second value of the shock J2(V).

[0068] In a third operation, the acceleration of the first vehicle 10 is controlled according to the acceleration value(s) determined in the second operation.

[0069] For example, the acceleration value(s) determined in the second operation and obtained at the output of the ACC system are used as the target acceleration(s) to regulate the acceleration of the first vehicle 10.

[0070] According to one variant, the acceleration value(s) determined in the second operation and obtained at the output of the ACC system are compared to accelerations determined by another module of the speed control system of the first vehicle 10. For example, the acceleration values ​​obtained at the output of the ACC system are compared to acceleration values ​​determined by a speed control system using as parameters a setpoint speed (for example, entered by the driver) and the current speed of the first vehicle 10. The comparison makes it possible to select the acceleration with the smallest value at a time 't', i.e., either the acceleration obtained at the output of the ACC system, or the acceleration obtained at the output of the speed control system, the selected acceleration value being used as the setpoint acceleration to regulate the acceleration of the first vehicle 10.

[0071] According to another variant, filtering is applied to the setpoint acceleration (obtained from the ACC system or the speed control system), for example to limit acceleration variations according to parameters stored in the memory of the acceleration control system of the first vehicle 10, for passenger comfort for example.

[0072] The first, second and third operations are thus implemented to determine at a current instant an acceleration value of the ACC system after loss of the target vehicle by the ACC system.

[0073] According to one embodiment, the first, second, and third operations are repeated for a predetermined duration (e.g., 2 seconds), for example, at regular intervals with a predetermined time step dt, for example, equal to 50 ms. According to this embodiment, an acceleration value is determined by the ACC system every 50 ms for 2 seconds, starting from the moment the vehicle that previously corresponded to the target vehicle is deselected as the target vehicle by the ACC system.

[0074] [ Fig. 2 ] illustrates functions of the shock value C as a function of the danger level N danger, according to a particular and non-limiting embodiment of the present invention.

[0075] There figure 2illustrates a first curve 21 showing the values ​​taken by the shock value C 1 as a function of the hazard (or criticality) level N hazard, that is to say when the shock value is greater than 0. Curve 21 includes, for example, 3 parts: a first part where C 1 takes a first value C 1_low, for example equal to 1 ms -3< , when the level of danger is less than a first threshold N low, for example equal to 0.2; a second part where C 1 corresponds to a linear increasing function, C 1 being between the first value C 1_low and a second value C 1_high, for example equal to 3 ms -3< , C 1_low being associated with N low and C 1_high being associated with a second threshold N high of the level of danger, for example equal to 0.9; and a third part where C 1 takes the second value C 1_high when the level of danger is greater than the second threshold N high.

[0076] There figure 2illustrates a second curve 22 showing the values ​​taken by the shock value C2 as a function of the hazard (or criticality) level Nhazard, that is, when the shock value is less than 0. Curve 22 comprises, for example, 3 parts: a first part where C2 takes a first value C2_low, for example equal to -1 ms -3< , when the danger level is less than the first threshold N low, for example equal to 0.2; a second part where C2 corresponds to a linear decreasing function, C2 being between the first value C2_low and a second value C2_high, for example equal to -6 ms -3< , C2_low being associated with N low and C2_high being associated with the second threshold N high of the danger level, for example equal to 0.9; and a third part where C2 takes the second value C2_high when the danger level is greater than the second threshold N high.

[0077] There figure 4Figure 4 schematically illustrates a device configured to control the acceleration of a vehicle, for example the first vehicle 10, according to a particular and non-limiting embodiment of the present invention. The device 4 corresponds, for example, to a device embedded in the first vehicle 10, for example a computer.

[0078] Device 4, for example, is configured to implement the operations described alongside the figures 1 to 3 and / or steps of the process described in relation to the figure 5Examples of such a device 4 include, but are not limited to, embedded electronic equipment such as a vehicle's on-board computer, an electronic control unit such as an ECU (Electronic Control Unit), a smartphone, a tablet, or a laptop computer. The elements of the device 4, individually or in combination, may be integrated into a single integrated circuit, into several integrated circuits, and / or into discrete components. The device 4 may be implemented as electronic circuits, software (or computer) modules, or a combination of electronic circuits and software modules.

[0079] The device 4 comprises one (or more) processor(s) 40 configured to execute instructions for carrying out the steps of the process and / or for executing instructions from the software embedded in the device 4. The processor 40 may include integrated memory, an input / output interface, and various circuits known to those skilled in the art. The device 4 further comprises at least one memory 41, corresponding, for example, to volatile and / or non-volatile memory, and / or includes a memory storage device that may include volatile and / or non-volatile memory, such as EEPROM, ROM, PROM, RAM, DRAM, SRAM, flash, magnetic disk, or optical disk.

[0080] The computer code of the embedded software(s) including the instructions to be loaded and executed by the processor is, for example, stored on memory 41.

[0081] According to various specific and non-limiting embodiment examples, device 4 is coupled in communication with other similar devices or systems (e.g. other computers) and / or with communication devices, e.g. a TCU (Telematic Control Unit), e.g. via a communication bus or through dedicated input / output ports.

[0082] According to a specific and non-limiting embodiment, device 4 includes a block 42 of interface elements for communicating with external devices. The interface elements of block 42 include one or more of the following interfaces: radio frequency (RF) 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 2.4 GHz frequency band, or of the Sigfox type using UBN (Ultra Narrow Band) radio technology, or LoRa in the 868 MHz frequency band, LTE (Long-Term Evolution), LTE-Advanced; USB (Universal Serial Bus) interface; HDMI (High Definition Multimedia Interface); LIN (Local Interconnect Network) interface.

[0083] Data is for example loaded to device 4 via the interface of block 42 using a Wi-Fi ®< network such as according to IEEE 802.11, an ITS G5 network based on IEEE 802.11p or a mobile network such as a 4G (or 5G) network based on the LTE (Long Term Evolution) standard defined by the 3GPP consortium, in particular an LTE-V2X network.

[0084] According to another specific and non-limiting embodiment, the device 4 includes a communication interface 43 that enables communication with other devices (such as other computers in the embedded system) via a communication channel 430. The communication interface 43 corresponds, for example, to a transmitter configured to transmit and receive information and / or data via the communication channel 430. The communication interface 43 corresponds, for example, to a wired CAN (Controller Area Network) type network. FD (from the English "Controller Area Network Flexible Data-Rate" or in French "Réseau de contrôles à débit de données flexible"), FlexRay (standardized by the ISO 17458 standard) or Ethernet (standardized by the ISO / IEC 802-3 standard).

[0085] In one particular, non-limiting embodiment, device 4 can provide output signals to one or more external devices, such as a display screen (touchscreen or not), one or more speakers, and / or other peripherals (projection system), via respective output interfaces. In one variant, one or more of the external devices is integrated into device 4.

[0086] There figure 5 illustrates a flowchart of the different stages of a method for controlling the acceleration of a vehicle, for example, the first vehicle 10, according to a particular and non-limiting embodiment of the present invention. The method is implemented, for example, by a device embedded in the first vehicle 10 or by the device 4 of the figure 4The process is implemented, for example, by one or more processors in one or more control units, such as one or more control units controlling the vehicle's ACC system. The process is implemented following the deselection of a second vehicle as the target vehicle of the ACC system.

[0087] In a first step 51, a representative value of a current acceleration variation, called the current jolt value, is determined as a function of a current speed of the first vehicle and an acceleration value, called the previous acceleration value, obtained from the ACC system at a time before the current time.

[0088] In a second step 52, a current acceleration value of the ACC system is determined as a function of the current jolt value and the previous acceleration value.

[0089] In a third step 53, the acceleration of the first vehicle is controlled according to the current acceleration value.

[0090] According to one variant, the variants and examples of the operations described in relation to the figure 1, 2 and / or 3 apply to the steps of the process of the figure 5 .

[0091] Of course, the present invention is not limited to the embodiments described above but extends to a method for controlling a vehicle, for example an autonomous vehicle, which would include secondary steps without falling outside the scope of the present invention. The same would apply to a device configured for implementing such a method.

[0092] The present invention also relates to an adaptive speed control system for vehicles comprising device 4 of the figure 4 .

[0093] The present invention also relates to a vehicle, for example a motor vehicle or more generally an autonomous land-powered vehicle, comprising device 4 of the figure 4 or the adaptive cruise control system for the above-mentioned vehicle.

Claims

1. Method for controlling the acceleration of a first vehicle (10), said first vehicle (10) comprising an adaptive speed regulation system, called an ACC system, said method comprising the following steps after a deselection of a second vehicle (11) as a target vehicle of said ACC system: a) determination (51) of a value representative of a current acceleration variation, referred to as the current shake value, as a function of a current speed of said first vehicle (10) and of an acceleration value, referred to as the previous acceleration value, obtained from said ACC system at an instant preceding said current instant; b) determination (52) of a current acceleration value of the ACC system based on the current shake value and the previous acceleration value; c) checking (53) the acceleration of said first vehicle (10) as a function of said current acceleration value.

2. Method according to claim 1, wherein said current shake value corresponds to: - a first shaking value when said previous acceleration value is strictly less than 0, said first shaking value being according to a first function of the speed of said first vehicle (10); or - second value of shaking when said previous acceleration value is greater than or equal to 0, said second value of shaking being according to a second function of the speed of said first vehicle (10).

3. Method according to claim 2, wherein said first shake value is: - equal to a first minimum shaking value for any speed of said first vehicle (10) comprised between 0 and a first minimum speed, according to an increasing function of the speed of said first vehicle when said speed of said first vehicle (10) lies between said first minimum speed and a first maximum speed of said first vehicle (10), said first maximum speed being greater than said first minimum speed, and - equal to a first maximum shaking value for any speed of said first vehicle (10) greater than said first maximum speed; and said second shake value is: - equal to a second minimum shaking value for any speed of said first vehicle (10) lying between 0 and a second minimum speed, said second minimum shaking value being less than said first minimum shaking value, according to an increasing function of the speed of said first vehicle (10) when said speed of said first vehicle lies between said second minimum speed and a second maximum speed of said first vehicle (10), said second maximum speed being greater than said second minimum speed, and - equal to a second maximum shaking value for any speed of said first vehicle (10) greater than said second maximum speed, said second maximum shaking value being less than said first maximum shaking value.

4. Method according to claim 3, wherein said second minimum speed is greater than said first minimum speed and said second maximum speed is greater than said first maximum speed.

5. Method according to one of claims 1 to 4, for which the said current acceleration value of the said ACC system is equal to: A t = A t − dt + J V * dt , with A(t) said current acceleration value, A(t-dt) said previous acceleration value, dt the time interval separating the previous instant and the current instant, J(V) said jolt value as a function of the speed V of said first vehicle (10).

6. Method according to one of claims 1 to 5, for which the said steps a), b) and c) are repeated for a determined period starting from a time instant corresponding to the said deselection of the said second vehicle (11).

7. Method according to claim 6, for which said determined duration is equal to 2 seconds.

8. Device (4) for controlling the acceleration of a first vehicle (10), said device (4) comprising a memory (41) associated with at least one processor (40) configured for implementing the steps of the method according to any one of claims 1 to 7.

9. Vehicle (10) comprising the device (4) according to claim 8.

10. A computer plan product comprising instructions adapted for executing the steps of the method according to one of claims 1 to 7, when the computer plan is executed by at least one processor.