Safety system for a vehicle for avoiding collision with objects, and a method in connection with the safety system.

Field of the invention

The present invention relates to a safety system and a method in connection with the safety system, according to the preambles of the independent patent claims. Specifically, the invention relates to a safety system for vehicles intended to facilitate and improve safety in connection with avoiding collision with objects appearing in front of the vehicle, by initiating a driver controlled avoidance manoeuvre with active steering.

Background of the invention

If an obstacle appears in front of the vehicle, it is possible to avoid a collision by steering around the object or by braking. Research shows that a large number of drivers do not react in time to steer around the obstacle or brake if it is too close.

There are numerous systems and methods to calculate a vehicle's travel path based on the appearance of the environment in front of the vehicle, and also for detection of an obstacle in front of the vehicle and to calculate and make decisions regarding suitable measures to avoid the obstacle. Below is a

description of some systems of this type.

US-771 1466 describes a method for a vehicle's avoidance manoeuvre where the problem with the driver's reflex to rotate the steering wheel in the "wrong" direction compared to an applied steering torque is mentioned. The system waits during a period of time to determine whether it is a reflex action, but if the driver's opposite steering wheel movement continues for a longer period, it is interpreted as a conscious action by the driver, and the automatic avoidance manoeuvre is ended. When determining whether an avoidance manoeuvre should take place, information regarding potential obstacles in front of the vehicle is gathered. This is achieved by, among other things, a set of CCD-cameras in order to produce a three dimensional picture of the area in front of the vehicle. In addition, calculations are based on the vehicle's speed. With regard to the gathered information, the vehicle's future travel path can be calculated and a decision can be made regarding how a collision will be avoided, e. g. via an avoidance manoeuvre.

In the article "Anticollision system PRORETA with automatic braking and steering" (M. Schorn, U. Stahlin (2008), Vehicle System Dynamics: International Journal of Vehicle Mechanics and Mobility, 46:S1 , pp. 683-694) methods and results regarding collisions avoidance are discussed, and driver assisted systems are described, including automatic object detection, prediction of travel path and controlled braking and steering. The objects are detected by using input data from LIDAR (Light Detection and Ranging) detection and video camera images showing the position, size and speed of the object in front of the vehicle. A predicted travel path is calculated depending on the distance, the vehicle's turning radius and the difference in speed between the vehicle and the object. Automatic braking is effected with an electrohydraulic brake, and automatic steering is effected with active steering of the front wheels. Methods for determining whether braking or steering, or both, should be used to avoid a collision with the object, are also described.

A system using the driver's reflexes is described in DE-102007016799 which describes a method for a vehicle to avoid obstacles by making a quick rotation of the steering wheel without affecting the direction of the wheels. The driver' reflex is thus triggered and the driver steers the vehicle away in the opposite direction. The quick rotation of the steering wheel is thus made in the opposite direction of the desired avoidance manoeuvre.

In certain situations, an automatic emergency brake of the vehicle is not sufficient to avoid a collision, for example if the vehicle's speed is too high and the distance to the object too short to have time to brake to a standstill.

Instead, an automatic avoidance manoeuvre using active steering of the vehicle may be preferable. For vehicles equipped with such systems it is important to let the driver take control over the vehicle to complete the avoidance manoeuvre, as soon as possible after an automatic steering intervention has been made.

There is a desire to further improve safety for vehicles in connection with the use of automatically generated avoidance manoeuvres, in order to avoid collisions with an eventual object that turns up in front of the vehicle, while at the same time allowing the driver, as far as possible, to actively steer the vehicle. The objective of the invention is thus to provide an improved system and method which achieves this. Summary of the invention

The above mentioned objectives are achieved with the invention as defined by the independent patent claims.

The preferred embodiments are defined by the dependent patent claims.

According to one embodiment of the invention, the invention is realised as follows:

1 . The control system superimposes a steering angle, such that the vehicle's front wheels are steered in the direction of the avoidance manoeuvre, i.e. the control system starts the avoidance manoeuvre. This causes a steering wheel torque in the opposite direction, i.e. the driver perceives that the steering wheel is steering the vehicle toward the object instead. The steering wheel torque generated in the "wrong" direction is a consequence of the control system's construction.

2. This steering wheel torque in the "wrong" direction activates the driver's reflex, which means the driver attempts to avoid a collision, i.e. applies a steering wheel torque in the "right" direction, i.e. the reflex to steer the vehicle in the same direction as the avoidance manoeuvre which the active control system has started. 3. The steering interference triggers the driver to carry out an avoidance manoeuvre. The automatic control system intervenes only at the beginning of the avoidance manoeuvre, taking over control for a maximum of one second. This means that when the driver reacts and steers in the right direction, he/she resumes control over the vehicle.

One advantage of this invention is that the vehicle is automatically steered so that the obstacle is avoided, and that the driver is triggered to react so that a torque is applied to the steering wheel by the driver, which supports the automatically generated swerve, while the driver takes back responsibility for the vehicle at the same time.

Brief description of drawings

Fig 1 is a schematic block diagram which illustrates the present invention.

Figure 2 is a flowchart which illustrates the method according to the invention. Figure 3 is a flowchart which illustrates an embodiment of the method according to the invention.

Detailed description of preferred embodiments of the invention

The invention is described below with reference to the enclosed figures.

Figure 1 shows a schematic block diagram which illustrates the invention comprising a safety system 2 for a vehicle, comprising a monitoring device 4 adapted to detect an object 6 within the proximity of the vehicle and to emit an indication signal 8 depending on the detected object 6. The vehicle may be a truck or a bus, but the system is also applicable to cars. The monitoring device may consist of forward-facing cameras, for example of CCD-type, LIDAR-systems, and other similar systems that are able to detect objects in front of the vehicle. Further examples of suitable systems that are able to function as monitoring devices have been provided in the prior art, discussed in the background section of this description. The indication signal 8 comprises object information, among other things regarding the direction of and distance to the object.

Further, the safety system comprises a wheel control device 10 adapted to impact the vehicle's wheel steering depending on the first steering signal 12 by changing the direction of the vehicle's wheels 3, i.e. by steering the vehicle, a steering wheel unit 14 adapted to apply a torque to the vehicle's steering wheel 16 for a predetermined duration depending on a second steering signal 18.

The safety system 2 also comprises an analysis device 20 adapted to receive the indication signal 8 and also a set of vehicle parameters 22, containing among others information regarding the vehicle's speed. The analysis device 20 is also adapted to analyse the indication signal 8 with respect to the direction of and distance to the object 6 and with respect to said set of vehicle parameters 22, to determine whether the vehicle is at risk of colliding with the object 6.

The analysis of the indication signal and the set of vehicle parameters then takes place, e.g. in the manner described above in the background section of this description.

If the result of the analysis shows that the vehicle risks colliding with the object 6, the analysis device 20 is adapted to generate a first steering signal 2, which means that the wheel steering device 10 changes the vehicle's direction so that the object 6 is avoided, and to generate, essentially at the same time as the first steering signal 12, a second steering signal 18 which means that the steering wheel unit 14 applies a torque to the steering wheel 16 for a predetermined duration, in a direction such that the steering wheel movement entails the driver perceiving that the vehicle is steered toward the object 6.

The torque applied to the steering wheel is thus in the opposite direction of a steering wheel movement which would entail that the object is avoided.

Preferably, the duration of the automatic steering is limited, for example to a period in the range of one second. According to one embodiment, the torque movement entails the steering wheel being turned to a maximum predetermined angle of 5 degrees. It is preferred that the predetermined duration is no longer than 0.5 seconds, and more preferably shorter than 0.2 seconds.

According to one embodiment, the wheel steering unit and the steering wheel unit are adapted to function independently of each other, which means, for example, that the wheel steering unit can be steered to impact the wheels so that the vehicle turns left while the steering wheel unit applies a torque to the steering wheel which corresponds to the vehicle turning right.

The wheel steering unit and the steering wheel unit are naturally adapted normally to cooperate, i.e. a steering wheel movement to turn in a certain direction entails that the wheels are impacted to turn, so that the vehicle turns in this direction. According to yet another embodiment, the steering wheel unit 14 is adapted to detect a torque applied to the steering wheel and to emit a detection signal 19 to the analysis device 20 depending thereon. If a torque is detected after the torque has been applied to the steering wheel, and which is in a direction so that a collision with the object is avoided, the wheel steering unit is adapted to be controlled by this torque movement, i.e. the driver takes over control and achieves the avoidance manoeuvre.

If a system with active steering with superimposition is used, entailing among others that the steering wheel turns with the system's movement, an opposite brief rotation of the steering wheel is obtained, entailing that the driver turns back the steering wheel as a reflex, and allows the movement which the active steering has initiated to avoid the obstacle.

This may be realised with an active steering system which operates with so-called angle overlay, i.e. a planetary gearbox may be installed in the steering column, which gearbox is connected to an electric engine that can emit an angle signal which is superimposed on the driver's steering wheel angle signal. The avoidance manoeuvre is triggered by the system, but the driver carries out the manoeuvre.

One example of overlay steering for a vehicle is described in EP-1754648, which relates to an overlay device that combines a steering wheel angle from the driver with another steering angle from another unit, to create a starting angle which then impacts the steering.

The invention also relates to a method for a safety system of a vehicle, this method being described below with reference to the flow chart in Figure 2.

The safety system comprises, as described above with reference to Figure 1 , a monitoring device adapted to detect an object within the proximity of the vehicle, and to emit an indication signal depending on the detected object. The indication signal comprises object information, among others regarding the direction of and distance to the object. The safety system also comprises a wheel control device adapted to impact the vehicle's wheel steering depending on a first steering signal, a steering wheel unit adapted to apply a torque to the vehicle's steering wheel for a predetermined duration, depending on a second steering signal. The safety system also comprises an analysis device adapted to receive the indication signal and also a set of vehicle parameters, containing information regarding the vehicle's speed, etc.

The method comprises the step

A - analysing said indication signal with respect to the direction of and distance to the object and with respect to said set of vehicle parameters, determining whether the vehicle is at risk of colliding with the object.

If the result of the analysis shows that the vehicle is at risk of colliding with the object, the method comprises the steps:

B - generating a first steering signal which entails that the wheel steering unit changes the direction of the vehicle so that the object is avoided, and

C - generating, essentially at the same time as the first steering signal, a second steering signal entailing that the steering wheel unit applies a torque to the steering wheel for a predetermined duration, in a direction such that the steering wheel movement entails the driver perceiving that the vehicle is steered toward the object.

The torque movement applied to the steering wheel at step C entails that the steering wheel is turned at a predetermined angle, 5 degrees, and the

predetermined duration preferably is no longer than 0.5 seconds, and more preferably no longer than 0.2 seconds.

As mentioned above in connection with the description of the safety system, the wheel steering unit and the steering wheel unit are adapted to function independently of each other. According to another embodiment, which is illustrated by the flow chart in Figure 3, the steering wheel unit is adapted to detect a torque movement of the steering wheel, and if a torque movement is detected after step C and which is in a direction so that a collision with the object is avoided, the wheel steering unit is adapted to be controlled by such torque.

The present invention is not limited to the above described preferred

embodiments. Various alternatives, modifications and equivalents may be used. The embodiments above shall therefore not be deemed to limit the scope of the invention, which is defined by the enclosed patent claims.