Driving assistance for intersections

Abstract

The invention relates to a driver assistance device that activates when a vehicle (1) approaches an intersection (3) of traffic lanes (2) and the driver signals a change of direction: if the automatic deceleration that the ECU (4) can apply is insufficient, it is rejected, and the driver is immediately alerted to allow them to prepare to brake. (Fig. 1)

Description

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

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

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

[0003] Driver assistance systems, also known as ADAS, are present on most modern motor vehicles. They include various functions designed to relieve the driver of certain tasks, or to meet legal or safety requirements, for example speed limits, proper obstacle avoidance, safe 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 systems determine speed changes that should be applied to the vehicle under certain driving circumstances. The invention relates to an improvement of a particular function of pACC, which is used when the vehicle approaches an intersection and the driver has indicated their intention 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 predetermined target speed. The deceleration may vary in intensity, or begin only after a delay, depending on the vehicle's speed and its distance from the intersection. However, it sometimes happens that the driver signals their intention to turn too late for this target speed to be reached, even with the strongest possible deceleration.

[0006] The consequence is that the driver will approach the intersection in poor conditions, at an excessive speed that he may not have anticipated. He may also mistakenly suspect a malfunction of the pACC function, whether or not automatic deceleration has been initiated, especially since the deceleration can vary in intensity and / or begin after the turn signal has been given.

[0007] Moreover, even if the driver has been warned by an overspeed alert, he may not interpret it correctly: the alerts are in fact likely to be numerous, and caused by entirely different reasons, with complex ADAS; 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 an inadequacy of the automatic deceleration in the event of a too late indication of the change of direction, or of informing him in an ambiguous way or which he may judge inconsistent, if for example he receives an alert while feeling that the automatic deceleration is taking place, or of warning him with delay if an overspeed alert is given only near the intersection. Description of the invention

[0009] The invention aims to remedy all or part of the disadvantages of the prior art by proposing a driving assistance device equipped with a pACC function of 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 an inevitable overspeed at the intersection if said automatic deceleration were applied, and thus 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 a change of direction indication has been given by a driver of the vehicle; the device being arranged to determine, as soon as the change of direction indication is given in front of 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] Because the determination is extremely rapid, the driver will be warned immediately after indicating their change of direction: they will easily associate the warning with their indication, and if they persist in their intention to change direction, they will be prompted to reduce the vehicle's speed themselves by voluntarily braking. They will then approach the intersection in better conditions of safety thanks to a 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, for the purposes 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 as above is a specific alert, that is to say distinct in particular from overspeed alerts, issued 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 includes 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, particularly favorably, consist of an image on a vehicle dashboard, which replaces a different image displayed when the automatic deceleration function is active: it is then perfectly specific, and informs the driver without any 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 to the intersection deemed to be 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 control device or unit according to the above; it may include, 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 features and advantages of the invention will become apparent from the following description, with reference to the attached figures, which illustrate a given embodiment by way of pure illustration: • [Fig.1]: 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 vehicle control unit; • [Fig.5]: a flowchart of the deceleration function; • [Fig.6]: a portion of the vehicle's dashboard. Detailed description of an implementation method

[0022] Fig. 1 illustrates a motor vehicle 1 moving along a road 2 leading to an intersection 3. The intersection 3 shown is of the branch type on a straight road, but it could also be a Y or goose foot (Fig. 2), or a T (Fig. 3), among others. Vehicle 1 includes ([Fig. 4]) one or more ECUs (electronic control units) 4 sensitive to various sensors 5 and capable of controlling actuators 6 of vehicle 1. More specifically, ECU 4 includes an Advanced Driver Assistance System (ADAS) 7, sensitive in particular to an intersection distance measuring device 8, a speedometer 9 measuring the speed of vehicle 1, and a sensor 10 for the activation of the flashing lights 11 of vehicle 1. The ADAS 7 is capable of regulating the engine speed 12 of vehicle 1 by some of the actuators 6, and of displaying operating information on a human-machine interface (HMI) 13 in order to inform the driver of vehicle 1.The human-machine interface 13 includes various levers and pedals available to the driver, including an actuation lever 18 for the flashing lights 11, the switching 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 speedometer 9, and the actuation sensor 10 are considered to be part of the sensors 5. The intersection distance measuring means 8 can, in practice, be a known on-board mapping device. Other possible 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, using the flowchart in [Fig. 5], the operation of ADAS 7 as the vehicle approaches intersection 3. The function enhanced by the invention becomes active if the driver activates the turn signals 11, thus indicating their intention to change direction (step E1). ADAS 7 then calculates the deceleration that should be applied to vehicle 1 to reach intersection 3 at a target speed deemed sufficiently low, based in particular on the speed of vehicle 1 and its distance from intersection 3 at that moment (step E2). The target speed can be fixed, or depend, for example, on geometric parameters of intersection 3 (angle, radius of curvature, lane width 2, etc.). ADAS 7 then determines whether this deceleration is less than a maximum deceleration at A possible automatic deceleration, corresponding for example to a value deemed dangerous or uncomfortable for the passengers of vehicle 1 (step E3), is triggered. If so, automatic deceleration is effectively applied to engine 12 by ADAS 7 (step E4), without driver intervention, and vehicle 1 will automatically approach intersection 3 at the target speed. This 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 surface grip, the weight of the loaded vehicle 1, etc.

[0025] If not, the improved version of the invention comes into play: 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 can be audible, visual, or both. It is important that it be early and, as far as possible, unambiguous. The early nature of the alert is made possible by the high speed of execution of the calculation and determination steps E2 and E3, which allows the alert to be issued almost as soon as the actuating lever 18 has been moved. This near-instantaneous reaction helps to inform the driver unambiguously, as well as certain preferred alert modes, which exploit the specific 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, especially when combined with the audible alert, consists of displaying a particular image on the instrument panel 19 of the vehicle 1 in this refusal situation, which replaces the usual image when the adaptive cruise control (ACC) is in operation. Figure 6 illustrates an image 14 of active ACC showing the predicted route of the vehicle 1, and here alongside other images 15 indicating the permitted 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 permitted, the sector 16 may appear green, but red if it is refused.

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

[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 has been 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 above by way of example. It is understood that a person skilled in the art is able to carry out different embodiments without departing from the invention.

Claims

Demands

1. A driver assistance device (7) for a motor vehicle (1), comprising an automatic deceleration function before intersections (3) of lanes (2) over which the vehicle is moving, and for which a change of direction indication has been given by a driver of the vehicle; the device (7) being arranged to determine (E3), as soon as the change of direction indication is given before 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, issued 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 includes an audible signal.

5. Driving assistance device according to any one of claims 1 to 4, characterized in that the alert includes 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 driver assistance device (7)

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