Patent Application
20070179697
The present invention relates generally to a lane departure warning system and method. In particular, the present invention relates to a vehicle lane departure warning system and method that uses the vehicle braking system to provide tactile feedback to the driver.
Various lane departure warning systems have been developed. Such systems typically incorporate a lane departure sensor that provides an electrical signal in the event that the vehicle unintentionally departs from the intended path or track of travel, as measured or indicated by the lane markers on the roadway, for example. One known system responds to such a signal by pulsing the steering system to provide tactile feedback to the driver through the steering wheel.
In one aspect the invention relates to a method of providing a lane departure warning to a vehicle driver by tactile feedback through the vehicle steering wheel. The method includes the steps of sensing a lane departure of the vehicle; in response to the sensing step, applying braking force to a steerable road wheel of the vehicle; and transmitting force from the steerable road wheel to the vehicle steering wheel, thereby to provide tactile feedback through the steering wheel.
In another aspect the invention relates to apparatus for providing tactile feedback to a driver of a vehicle having left and right steerable road wheels and a steering wheel for controlling the steerable road wheels. The braking system includes a left brake associated with the left steerable road wheel, a right brake associated with the right steerable road wheel, and a brake pedal operable by a driver of the vehicle for applying the left and right brakes. The apparatus also includes a lane departure sensor, and an electronic control unit operatively connected with the lane departure sensor, the electronic control unit being operable to apply one of the left and right brakes in response to sensing an unintended lane departure of the vehicle without driver input through the brake pedal.
In another aspect the invention relates to apparatus usable in a vehicle braking system for providing tactile feedback to a driver of a vehicle having a steering wheel and left and right steerable road wheels. The apparatus includes a lane departure sensor, and an electronic control unit operatively connected with the lane departure sensor, the electronic control unit providing a control signal for controlling the vehicle brakes in response to sensing an unintended lane departure of the vehicle without driver input through the brake pedal.
In another aspect the invention relates to apparatus for providing a lane departure warning to a vehicle driver through tactile feedback in the vehicle steering wheel. The apparatus includes means for sensing an unintended lane departure of the vehicle, and means responsive to the means for sensing for applying braking force to a steerable road wheel of the vehicle, thereby to provide tactile feedback through the steering wheel.
The foregoing and other features of the present invention will become apparent to one skilled in the art to which the present invention relates upon consideration of the following description of the invention with reference to the accompanying drawings, in which:
The present invention relates generally to a lane departure warning system and method. In particular, the present invention relates to a vehicle lane departure warning system and method that uses the vehicle braking system to provide tactile feedback to the driver. The present invention is applicable to systems of varying constructions. As representative of the invention,
The system 10 is located on a vehicle 12 (
The vehicle 12 has a steering wheel 22. The steering wheel 22 is rotatable by the vehicle driver to control the steering angle of the front wheels 14 and 16. A linkage of some type, indicated schematically at 24, connects the steering wheel 22 with the front wheels 14 and 16. The linkage 24 provides control force from the steering wheel 22 to the front wheels 14 and 16 and may include a power assist mechanism, for example.
The linkage 24 also provides feedback from the front wheels 14 and 16 to the steering wheel 22. Thus, for example, when one of the front wheels 14 and 16 hits a bump or a curb or starts to turn, that is sensed in the steering wheel 22 as a rotational force on the steering wheel not provided by the driver. Thus, tactile feedback is provided to the driver.
The braking system 10 may be a pneumatic braking system or a hydraulic braking system. In an embodiment for a large commercial vehicle, the braking system is typically a pneumatic braking system. The braking system 10 includes a left front brake, shown schematically at 30, that is associated with the left front wheel 14. The braking system 10 also includes a right front brake, shown schematically at 32, that is associated with the right front wheel 16. The braking system 10 also includes a brake pedal 34 by which the driver can cause braking force to be applied at the left front wheel 14 and the right front wheel of the vehicle 16.
The braking system 10 also includes an electronic control unit, or ECU, shown schematically at 40. The ECU 40 is capable of performing various functions in the braking system 10. For example, the ECU 40 is capable of causing the braking system to provide braking force to one or more of the wheels of the vehicle 12, without driver intervention via the brake pedal 34. The ECU 40 is capable of providing braking force to either one 14 or 16 of the front wheels of the vehicle 12, without providing braking force to the other one of the front wheels. Braking systems and ECUs of this type are found in different types of vehicle, for example in vehicles having electronic stability control.
The braking system 10 also includes a lane departure sensor, indicated schematically at 50, which is operatively connected to the ECU 40. The sensor that is shown at 50 may actually be one or more individual sensor units, and may be of any suitable type. The sensor 50 is operative to sense a lane departure. Specifically, the sensor 50 is operative to sense a departure from the intended lane of travel of the vehicle 12, either to the left or to the right. The sensor 50 in such a case outputs an appropriate signal to the ECU 40. Thus, the ECU 40 is provided with information indicating either a directionally left lane departure, or a directionally right lane departure.
It is possible that the vehicle 12 might unintentionally move out of its intended path, or track, or lane, of travel, by departing from the center lane 62. For example, the vehicle 12 might experience a directionally left lane departure, as indicated by the arrow 68. Or, the vehicle 12 might experience a directionally right lane departure, as indicated by the arrow 70.
If a lane departure should occur, the lane departure sensor 50 outputs an appropriate signal to the ECU 40. The ECU 40 is thus informed of the fact of the lane departure. The ECU 40 is also informed of the direction of the lane departure, that is, a directionally left lane departure or a directionally right lane departure.
The ECU 40 is programmed to respond to the signal from the lane departure sensor 50. Specifically, the ECU 40 is programmed to provide a control signal so as to cause braking force to be applied to one of the front wheels 14 and 16, in response to the sensing of a lane departure. The ECU 40 can cause braking force to be applied to the right front wheel 16 or to the left front wheel 14. For reasons described below, it may be desirable to cause braking force to be applied to the front wheel 14 and 16 that is on the side of the vehicle 12 opposite to the direction of lane departure.
Braking force is preferably applied to only one of the front wheels 14 and 16, not to both front wheels simultaneously. When this occurs, the front wheel that is braked slows down compared to the non-braked front wheel. In addition, the steerable wheels 14 and 16 turn relative to the longitudinal central axis of the vehicle 12. For example, if the right front wheel 16 is braked, the front wheels 14 and 16 turn to the right by at least a small amount.
The turning of the steerable wheels 14 and 16 is felt, by transmission of force back up through the steering linkage 24, to the steering wheel 22. The braking of the one wheel thus causes force to be transmitted from the wheels 14 and 16, through the linkage 24, to the vehicle steering wheel 22. This force is felt as a turning moment on the steering wheel 22—the steering wheel tries to turn in the driver's hands. For example, if the right front wheel 22 is braked, the vehicle steering wheel 22 turns to the right by at least a small amount. This turning motion or force of the steering wheel 22 constitutes tactile feedback to the driver of the vehicle 12, through the steering wheel 22, in response to the sensing of the lane departure.
An added effect of the wheel braking is that the vehicle 12 might tend to turn back toward its intended path. For example, if a directionally left lane departure is sensed, the right front wheel 16 can be braked, causing the vehicle 12 to tend to turn toward the right, thus countering the lane departure. Alternatively, if a directionally right lane departure is sensed, the left front wheel 14 can be braked, causing the vehicle 12 to tend to turn toward the left, thus countering the lane departure. The ECU 40 can optionally be programmed to operate in this manner. The amount of braking force that is applied is, by design, either (a) sufficient to cause a significant departure from the path or track of the vehicle 12, or (b) not sufficient to cause a significant departure from the path or track of the vehicle.
In another embodiment, the ECU 40 can cause braking force to be applied in an alternating manner, first to one and then to the other of two steerable road wheels 14 and 16 of the vehicle 12. This type of application of braking force can cause the vehicle steering wheel 22 to oscillate in the driver's hands, as another form of tactile feedback to the driver in the event of an unintended lane departure.
From the above description of the invention, those skilled in the art will perceive improvements, changes, and modifications in the invention. Such improvements, changes, and modifications within the skill of the art are intended to be included within the scope of the appended claims.
