CROSS-REFERENCE TO RELATED APPLICATION

[0001] This application claims the benefit under 35 U.S.C. § 119(e) of U.S.

Provisional Patent Application No. 62/112789, filed 06-Feb-2015, the entire disclosure of which is hereby incorporated herein by reference.

TECHNICAL FIELD OF INVENTION

[0002] The invention relates to vehicle system in which an adaptive cruise control system is integrated with an active lane keeping assist system.

BACKGROUND OF THE INVENTION

[0003] Earlier cruise control systems, decades old now, allowed a driver to set a certain speed, typically used on highways in fairly low traffic situations, where not a lot of stop and go traffic could be expected. This was necessary, as the systems could not account for closing of the distance behind a leading- vehicle. It was incumbent upon the driver to notice this, and step on the brake, which would also cancel the cruise control setting, necessitating that it be reset. This was an obvious annoyance in stop and go traffic, so the system would unlikely be used in that situation. The systems typically did not cancel the setting for mere acceleration, allowing for the passing of slower leading- vehicles, and a return to the set speed when the passing car returned to its lane. [0004] Newer cruise control systems, typically referred to as adaptive cruise control, use a combination of radar and camera sensing to actively hold a

predetermined distance threshold behind the leading car. These vary in how actively they decelerate the car, if needed, to maintain the threshold. Some merely back off of the throttle, some provide a warning to the driver and pre-charge the brakes, and some actively brake while providing a warning.

[0005] Appearing on vehicles more recently have been so called lane keeping systems, to keep or help to keep a vehicle in the correct lane. These also vary in how active they are. Some systems merely provide audible or haptic warnings if it is sensed that the car is drifting out of its lane, or if an approaching car is sensed as a car attempts to pass a leading car. Others will actively return the car to the lane if an approaching car is sensed.

SUMMARY OF THE INVENTION

[0006] The present disclosure provides an integrated active cruise control and lane keeping assist system. The potential exists for a car attempting to pass a leading car to fail in that pass attempt and be returned to the lane in which the leading car travels but too close to the leading car, or at least closer than the predetermined threshold that an active cruise control system would normally maintain.

[0007] In the preferred embodiment disclosed, the active cruise control system includes an additional and alternative deceleration scheme. If the vehicle fails in an attempt to pass a leading- vehicle, and makes a lane reentry behind the leading- vehicle that puts it at a following-distance less than the predetermined threshold normally maintained by the cruise control system, a more aggressive deceleration of the vehicle is imposed, as by braking or harder and longer braking, to return the vehicle quickly to the predetermined threshold-distance.

[0008] In another preferred embodiment a method of operating an adaptive cruise control system for use in a vehicle configured to actively maintain a following- distance behind a leading-vehicle at no less than a predetermined threshold-distance is provided. The method includes determining when a following-distance of a trailing- vehicle behind a leading- vehicle is less than a threshold-distance. The method also includes maintaining the following-distance when the following-distance is not less than the threshold-distance. The method also includes determining when the following-distance is less than a minimum-threshold that is less than the threshold- distance. The method also includes decelerating the trailing- vehicle at a normal- deceleration-rate when the following-distance is less than the threshold-distance and not less than the minimum-distance. The method also includes decelerating the trailing- vehicle at an aggressive-deceleration-rate when the following-distance is less than the minimum-distance.

BRIEF DESCRIPTION OF THE DRAWINGS

[0009] The foregoing and other features, and advantages of the invention are apparent from the following detailed description taken in conjunction with the accompanying drawings in which:

[0010] Fig. 1 is a schematic view of a trailing-vehicle following a leading- vehicle at the predetermined or normal threshold-distance; [0011] Fig. 2 is a view of the trailing-vehicle reentering its lane at and a distance from the leading-vehicle less than the predetermined threshold; and

[0012] Fig. 3 is a flow chart of the method comprising the subject invention.

DETAILED DESCRIPTION

[0013] Referring now to the Figures, the invention will be described with reference to specific embodiments, without limiting same.

[0014] Referring first to Figs. 1 and 3, a trailing-vehicle 10 equipped with a active cruise control system, hereafter the system 28, suitable for automated operation of the trailing-vehicle 10 is shown behind a leading-vehicle 12 at the predetermined or normal following threshold-distance T. A method 30 of operating the system 28 is illustrated in Fig. 3. At the logic box 14, the system 28 determines if the trailing- vehicle 10 is at and has maintained the threshold T. If not, as due to the leading- vehicle 12 slowing down, the decision box 16 illustrates that the active cruise control system will also slow down trailing-vehicle 10, by de-throttling, braking, or some combination of the two until the threshold following-distance is re attained.

[0015] Referring next to Figs. 2 and 3, the trailing-vehicle 10 is shown after trying and failing to pass the leading-vehicle 12, so the trailing-vehicle 10 is shifting fairly suddenly back to the original lane, while the system 28 is still engaged. As noted, this is an expected scenario as the trailing-vehicle 10 would normally not use the brake, but only accelerate, in order to change lanes and attempt to pass the leading- vehicle. This scenario would not disengage the system. If, due either to driver action or the effect of an active lane keeping system (i.e. the system 28), the trailing- vehicle 10 shifts abruptly back to the original lane, it could end up closer to the leading- vehicle 12 at a following-distance X less than a minimum-distance which is less than less than the threshold-distance T. In that event, the driver might not notice immediately, nor apply the brake quickly. In that case, as shown by the decision box 18, the cruise control system would switch to a more aggressive than normal deceleration scheme until the threshold T is again attained. In the event that the driver did apply the brake at some point still within the less than threshold- distance T, the system 28 could be configure not to disengage the active cruise control until the threshold-distance T was achieved.

[0016] The temporarily more aggressive deceleration would be beneficial regardless of whether the abrupt return to the original lane was due to driver direct action or the action of an active lane keeping system. However, it is particularly beneficial when the two are integrated, as a driver inattentive to an approaching vehicle in the adjacent lane is likely to be equally inattentive to the proximity of a leading- vehicle in the original lane.

[0017] While the invention has been described in detail in connection with only a limited number of embodiments, it should be readily understood that the invention is not limited to such disclosed embodiments.