Driving assistance for intersections

Abstract

The invention relates to a driving assistance device when a vehicle (1) approaches an intersection (3) of traffic lanes (2) and a change of direction is indicated by the driver: if the automatic deceleration that the ECU (4) can apply is insufficient, it is refused, and the driver is alerted immediately, to allow him to prepare for braking. (Fig. 1)

Description

Title of the invention: Driving assistance for intersections Technical field of the invention

[0001] The invention relates, in general, to assistance in driving motor vehicles at road intersections, when an indication of a change of direction has been given by the driver.

[0002] It relates more specifically to an improvement of a driving assistance device, capable of imposing automatic deceleration on the vehicle as soon as such an indication of change of direction has been given. State of the prior art

[0003] Driver assistance devices, also known as ADAS, are present on most modern motor vehicles. They include various functions intended to relieve the driver of certain tasks, or to meet legal or safety requirements, for example speed limitation, good consideration of obstacles, safety distance between vehicles, in different combinations depending on the vehicle model.

[0004] A common type of ADAS is ACC, also known as adaptive cruise control, one category of which is pACC, also known as predictive adaptive cruise control. These regulators determine speed changes that are desirable to impose on the vehicle in certain driving circumstances. The invention relates to an improvement of a particular function of pACC, which is used when the vehicle arrives at an intersection and the driver has indicated his desire to change direction.

[0005] Known pACC functions then apply automatic deceleration to the vehicle, without the driver having to brake, in order to allow the vehicle to turn under conditions deemed satisfactory when it has reached the intersection, and in particular without exceeding a determined target speed. The deceleration may have a variable intensity, or begin only after a delay, depending on the speed of the vehicle and its distance from the intersection. However, it may happen that the driver indicates his intention to turn too late for this target speed to be reached, even at the greatest possible deceleration.

[0006] The consequence is then that the driver will approach the intersection in poor conditions, with an excess speed that he will not necessarily have anticipated. He may also wrongly suspect a failure of the pACC function, whether automatic deceleration has been undertaken or not, especially since the deceleration may have a variable intensity and / or begin after the change of direction has been indicated.

[0007] Furthermore, even if the driver has been warned by an overspeed alert, he may not interpret it correctly: the alerts are indeed likely to be numerous, and caused by completely different reasons, with complex AD AS; and overspeed alerts can be applied to many other driving circumstances, including intersections equipped with traffic lights and for which an overspeed alert may be issued if the light is likely to turn red, even if the driver has no intention of changing direction.

[0008] The known devices therefore have the disadvantages of either not informing the driver of insufficient automatic deceleration in the event of too late indication of the change of direction, or of informing him in an ambiguous manner or in a manner which he may judge to be incoherent, if for example he receives an alert while feeling that automatic deceleration is occurring, or of warning him late if an overspeed alert is given only near the intersection. Statement of the invention

[0009] The invention aims to remedy all or part of the drawbacks of the state of the art by proposing a driving assistance device equipped with a pACC function for automatic deceleration at intersections, but which is arranged so as not to provide ambiguous or inconsistent impressions to the driver, but on the contrary to warn him clearly and without delay of inevitable overspeeding at the intersection if said automatic deceleration were applied, and therefore give him the ability to approach the intersection in better conditions.

[0010] To this end, according to a first aspect of the invention, a driving assistance device for a motor vehicle is proposed, comprising an automatic deceleration function in front of intersections of lanes on which the vehicle is moving, and for which an indication of a change of direction has been given by a driver of the vehicle; the device being arranged to determine, as soon as the indication of a change of direction is given in front of a said intersection, whether the change of direction can be carried out in a manner deemed satisfactory; and being characterized in that, if it determines that the change of direction cannot be carried out in a manner deemed satisfactory, the automatic deceleration function is made inactive, and an alert is given to the driver as soon as the determination is made.

[0011] As the determination is extremely rapid, the driver will be warned immediately after he has indicated his direction change indication: he will easily associate the alert with his indication, and he will be led, if he persists in his intention to change direction, to lower the speed of the vehicle himself by voluntary braking. He will then approach the intersection in better conditions of safety thanks to longer braking time.

[0012] The refusal of automatic deceleration, combined with the alert and which the alerted driver will immediately feel, will provide him with an additional incentive to temporarily take back control of the vehicle's speed to cross the intersection.

[0013] It is recalled that within the meaning of this text, “automatic deceleration” is a deceleration which is imposed by the ADAS alone, without the driver intervening on the function by acting on the pedals for example.

[0014] The determination may depend on a maximum value of the automatic deceleration; a target speed of the vehicle at the intersection; and an actual speed of the vehicle as well as a distance between the vehicle and said intersection when the direction change indication is given.

[0015] Advantageously, the alert such as above is a specific alert, that is to say distinct in particular from overspeed alerts, emitted by the device in particular in situations, without indication of change of direction, of speed deemed excessive of the vehicle.

[0016] According to one embodiment, the alert comprises an audible signal.

[0017] According to an embodiment that can be associated with the previous one, the alert includes a visual indication. It can then, in a particularly appreciated manner, consist of an image on a dashboard of the vehicle, which replaces a different image, displayed when the automatic deceleration function is active: it is then perfectly specific, and informs the driver without possible ambiguity.

[0018] The device is advantageously arranged to make the automatic deceleration function active again when said intersection has been crossed by the vehicle, thus limiting the refusal of automatic deceleration at the intersection deemed difficult to cross.

[0019] According to another aspect of the invention, it relates to an electronic control unit of a motor vehicle, comprising the driving assistance device according to the above.

[0020] Another aspect of the invention is a motor vehicle comprising the device or control unit according to the above; it may comprise, among other means, an on-board mapping device for measuring the distance between the vehicle and said intersections. Brief description of the figures

[0021] Other characteristics and advantages of the invention will emerge on reading the description which follows, with reference to the appended figures, which illustrate an embodiment given purely for illustrative purposes: • [Fig.l]: a schematic view of a vehicle in front of an intersection; • [Fig.2]: a view of another type of intersection; • [Fig.3]: a view of a third type of intersection; • [Fig.4]: a view of an electronic control unit of the vehicle; • [Fig.5]: a flowchart of the deceleration function; • [Fig.6]: a portion of the vehicle’s dashboard. Detailed description of an embodiment

[0022] [Fig.l] illustrates a motor vehicle 1 moving forward on a track 2 leading to an intersection 3. The intersection 3 shown is of the type of junction on a straight track, but it could also be Y-shaped or goose-foot ([Fig.2]), or T-shaped ([Fig.3]), among others. The vehicle 1 comprises ([Fig.4]) one or more ECUs (electronic control units) 4 sensitive to various sensors 5 and capable of controlling actuators 6 of the vehicle 1. More particularly, the ECU 4 comprises a driving assistance device (ADAS) 7, sensitive in particular to an intersection distance measuring means 8, a speedometer 9 measuring the speed of the vehicle 1, and an actuation sensor 10 for flashing lights 11 of the vehicle 1. The ADAS 7 is capable of regulating the speed of the engine 12 of the vehicle 1 by some of the actuators 6, and of displaying operating indications on a human-machine interface (HMI) 13 in order to inform the driver of the vehicle 1.The human-machine interface 13 comprises various levers and pedals available to the driver, in particular an actuation lever 18 for the flashing lights 11, the tilting of which is felt by the actuation sensor 10, and a dashboard 19 on which various images can be displayed and which also contains an audible warning device.

[0023] The intersection distance measuring means 8, the speed camera 9 and the actuation sensor 10 are considered as part of the sensors 5. The intersection distance measuring means 8 can concretely be a known on-board mapping device. Other conceivable devices would be a radar directed towards the front of the vehicle 1, a laser, a camera, or a GPS geolocation device.

[0024] We will now describe, by means of the flowchart of [Fig. 5], the operation of the ADAS 7 when approaching the intersection 3. The function improved by the invention becomes active if the driver turns on the flashing lights 11, thus indicating his desire to change direction (step E1). The ADAS 7 then performs a calculation of the deceleration that should be applied to the vehicle 1 to reach the intersection 3 at a target speed deemed sufficiently low, based in particular on the speed of the vehicle 1 and its distance from the intersection 3 at this time (step E2). The target speed can be fixed, or depend for example on geometric parameters of the intersection 3 (angle, radius of curvature, width of the lanes 2, etc.). The ADAS 7 then determines whether this deceleration is less than a maximum deceleration at automatic possible, corresponding for example to a value deemed dangerous or uncomfortable for the passengers of vehicle 1 (step E3). If so, automatic deceleration is actually applied to engine 12 by ADAS 7 (step E4), without driver intervention, and vehicle 1 will automatically approach intersection 3 at the target speed. The determination can be based on experimental deceleration curves recorded in ADAS 7 and possibly corrected by parameters such as the gradient of lane 2, road grip, the weight of the loaded vehicle 1, etc.

[0025] If not, the improvement of the invention comes into action: automatic deceleration is refused for intersection 3 (step E5), and an alert is simultaneously transmitted to the human-machine interface 13 (step E6). The alert may be audible, visual or both. It is important that it be early and as unambiguous as possible. The early nature of the alert is made possible by the great speed of execution of the calculation and determination steps E2 and E3, which makes it possible to issue the alert almost as soon as the actuating lever 18 has been switched. This almost instantaneous reaction contributes to informing the driver unambiguously, as well as certain preferred alert modes, which exploit the particular nature of the refusal of this automatic deceleration function, compared to a simple overspeed alert for example.

[0026] Thus, a visual alert specific to the invention consists, especially combined with the audible alert, in displaying a particular image on the dashboard 19 of the vehicle 1 in this refusal situation, which replaces the usual image when the adaptive cruise control (ACC) is in operation. [Fig. 6] illustrates an image 14 of active ACC illustrating the predictive path of the vehicle 1, and here alongside other images 15 indicating the authorized speed and the ACC set speed of the vehicle 1. The image 14 includes a sector 16 representing the intersection 3. If automatic deceleration is authorized, the sector 16 may appear in green, but in red if it is refused.

[0027] The driver therefore has sufficient time more easily, if he maintains his desire to change direction, to lower the speed of the vehicle 1 himself by braking it.

[0028] The other functions of ADAS 7 can remain active; the automatic deceleration function can be restored without driver intervention as soon as intersection 3 is passed; finally, it is envisaged not to normally add an overspeed alert when vehicle 1 arrives at intersection 3, since the driver has already been warned of a delicate driving circumstance.

[0029] Naturally, the invention is described in the above by way of example. It is understood that a person skilled in the art is able to produce different variant embodiments without departing from the invention.

Claims

Claims

1. Driving assistance device (7) for a motor vehicle (1), comprising an automatic deceleration function in front of intersections (3) of lanes (2) on which the vehicle is moving, and for which an indication of change of direction has been given by a driver of the vehicle; the device (7) being arranged to determine (E3), as soon as the indication of change of direction is given in front of a said intersection, whether the change of direction can be carried out in a manner deemed satisfactory; and being characterized in that, if it determines that the change of direction cannot be carried out in a manner deemed satisfactory, the automatic deceleration function is made inactive (E5), and an alert is given to the driver (E6) as soon as the determination is made.

2. Driving assistance device according to claim 1, characterized in that the determination depends on a maximum value of the automatic deceleration, a target speed of the vehicle at the intersection, and an actual speed of the vehicle as well as a distance between the vehicle and said intersection when the direction change indication is given.

3. Driving assistance device according to any one of claims 1 or 2, characterized in that the alert is distinct from overspeed alerts, emitted by the device in situations, without indication of change of direction, of speed deemed excessive of the vehicle.

4. Driving assistance device according to any one of claims 1 to 3, characterized in that the alert comprises an audible signal.

5. Driving assistance device according to any one of claims 1 to 4, characterized in that the alert comprises a visual indication.

6. Driving assistance device according to claim 5, characterized in that the visual indication is an image (14) on a dashboard (19) of the vehicle (1), which replaces a different image, displayed when the automatic deceleration function is active.

7. Driving assistance device according to any one of claims 1 to 6, characterized in that it is arranged to make the automatic deceleration function active again when said intersection (3) has been crossed by the vehicle (1).

8. Electronic control unit (4) of a motor vehicle, characterized in that it comprises the driving assistance device (7)

9. according to any one of the preceding claims. Motor vehicle (1), characterized in that it comprises the driving assistance device according to any one of claims 1 to 7.

10. Motor vehicle according to claim 9, characterized in that it comprises an on-board mapping device (8), as a means of measuring the distance between the vehicle and said intersections.

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