WO2016050253A1

WO2016050253A1 - Method to prevent from a collision between a vehicle and a front obstacle and vehicle associated with this method

Info

Publication number: WO2016050253A1
Application number: PCT/EP2014/002699
Authority: WO
Inventors: Laurent BOISSON
Original assignee: Volvo Truck Corporation
Priority date: 2014-10-02
Filing date: 2014-10-02
Publication date: 2016-04-07

Abstract

Method to prevent from a collision between a vehicle (2) and a front obstacle (16). The method comprises the step a) of assessing whether the vehicle (2) is too close to the front obstacle (16) in function of the distance (d) between the vehicle (2) and the front obstacle (16) and of the speed (S) of the vehicle (2). If the vehicle is too close to the front obstacle (16) the method further includes the following steps : b) determining (100, 102, 104, 106) a braking intensity in function of the distance (d) between the vehicle (2) and the obstacle (16) and of the speed (S) of the vehicle, c) determining (200, 202, 204, 206) an alert signal in function of the braking intensity determined at step b), d) emitting (300, 302, 304, 306) in the vehicle (2) the alert signal determined at step c) in order to alert the driver, e) automatically braking (400, 402, 404, 406) the vehicle (2) with the braking intensity determined at step b).

Description

METHOD TO PREVENT FROM A COLLISION BETWEEN A VEHICLE AND A FRONT OBSTACLE AND VEHICLE ASSOCIATED WITH THIS METHOD

TECHNICAL FIELD OF THE INVENTION

The present invention relates to a method to prevent from a collision between a vehicle and a front obstacle. The invention also concerns a vehicle, such as a truck, associated with this method.

BACKGROUND OF THE INVENTION

The invention can be applied in heavy-duty vehicles, such as trucks, buses and construction equipment. Although the invention will be described with respect to a truck, the invention is not restricted to this particular vehicle, but may also be used in other vehicles, such as traditional cars and vans. _, -

In the automobile industry, it is known to implement methods to prevent from a collision between a vehicle and an obstacle.

For instance, WO-A-2013/064 254 discloses a method for outputting alert messages to a diver of a vehicle. The more the risk of a collision with an obstacle is high, the more intensified are the alert messages. The alert messages are outputted by means of a flash light, whose the blinking frequency or the intensity is adapted in function of the situation. The risk of a collision is assessed in function of the speed of the vehicle, the direction of the latter and of the distance to the nearest obstacle. In case the driver does not react to the alert messages, or does not push the pedal brake at time, the vehicle is automatically stopped by application of an emergency brake at full capacity. Therefore, the brake is automatically applied only when the risk of collision with an obstacle is high. The collision is not anticipated. Moreover, the driver may panic following to the emergency braking operation, which can lead to an accident.

SUMMARY OF THE INVENTION

An object of the invention is to provide a method to prevent from a collision between a vehicle and a front obstacle, which allows anticipating situations with a risk of collision.

To this end, the invention concerns a method to prevent from a collision between a vehicle and a front obstacle, comprising the steps consisting in:

a) assessing whether the vehicle is too close to the front obstacle in function of the distance between the vehicle and the obstacle and of the speed of the vehicle, characterized in that if the vehicle is too close to the front obstacle the method includes the steps consisting in :

b) determining a braking intensity that is function of the distance between the vehicle and the obstacle and of the speed of the vehicle

c) determining an alert signal in function of the braking intensity determined at step b),

d) emitting in the vehicle the alert signal determined at step c) in order to alert the driver,

e) automatically braking the vehicle with the braking intensity determined at step b).

By the provision of a method which teaches to adapt the braking intensity automatically applied in function of the distance between the vehicle and the obstacle, and of the speed of the vehicle, the vehicle is not braked only in case of emergency. Indeed, the vehicle is automatically slowed down when it is considered that the latter nears the obstacle too fast. Moreover, the braking effort that is automatically applied is preferably increased gradually as the vehicle gets closer to the obstacle and an alert signal is determined in function of the determined braking intensity. Preferably, the alert signal is sent to the driver before automatic applications of the brakes of the vehicle and is preferably maintained during automatic braking of the vehicle. Consequently, the driver is not surprised by a sudden automatic brake application at full capacity and there is less risk of accident due to a panic of the driver. Moreover, this allows contributing to respect the safe distances with front obstacles.

According to further aspects of the invention, which are advantageous but not compulsory, such a method may incorporate one or several of the following features:

The braking intensity is determined depending on the speed of the vehicle relative to the obstacle.

- The braking intensity is determined depending on the slope of the road, the load of the vehicle and/or on weather conditions.

- The alert signal includes a light signal, whose intensity and/or flashing frequency is adapted at step b).

The alert signal includes a beep, whose intensity and/or frequency is adapted at step b).

The method includes a supplementary step that consists to jam the throttle of the vehicle when the latter is too close from the obstacle.

The braking intensity is adapted in a discrete manner. - The braking intensity is selected amongst at least three levels.

- At least two first braking levels aim each at decelerating the vehicle down to a threshold value and the last braking level aims at stopping the vehicle.

Steps a) can be performed by an ECU (electronic control unit) connected to detecting means that can be a distance radar provided on the vehicle or a navigation system able to transmit to the ECU information relative to the position of the front obstacle .

- Steps b) and c) can be performed by an ECU that can be the same as the one used for step a),

The automatic braking of step e) is triggered by an ECU which sent to the brake system of the vehicle, in order to activate the brakes of the vehicle, a control signal that is function of the braking intensity determined at step b).. The ECU triggering the automatic braking of step e) can be the same ECU as the one used at step b).

The invention also concerns a vehicle that comprises :

- detecting means and a first electronic control unit to assess whether the vehicle is too close to a front obstacle ,

a same or a second electronic control unit for :

• determining a braking intensity in function of the distance between the vehicle and the obstacle and of the speed of the vehicle,

• generating a control signal to trigger an automatic braking depending on the determined braking intensity,

• determining an alert signal in function of the determined braking intensity. The vehicle further comprises :

- a brake system to activate brakes of the vehicle in function of the control signal generated by the first or second control unit, and

- means for emitting the alert signal determined by the first or second control unit in the vehicle in order to alert the driver.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will now be explained in correspondence with the annexed figures, and as an illustrative example, without restricting the object of the invention. In the annexed figures:

- figure 1 is a side view of a truck according to the invention,

- figure 2 is a schematic view of the inside of the cabin of the truck of figure 1 , - figure 3 is a scheme showing different application configurations of a method to prevent a collision according to the invention,

- figure 4 is a graphic showing the steps to implement the method to prevent a collision, and

- figure 5 is a graphic showing the interactions between different components of the truck of figure 1 that contribute to the implementation of the method illustrated on figures 3 and 4.

DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS OF THE INVENTION

Figure 1 represents a vehicle 2 comprising a truck 6 and a a trailer 4. The truck 6 may comprise two pairs of wheels 10 and the trailer 4 may, for instance, comprise two pairs of rear wheels 10.

As shown on figure 2, the cabin of the truck 6 comprises a handwheel 12 and a dash board 13 including a speedometer 14. The speedometer 14 is configured to inform the driver of the speed of the vehicle. The speedometer 14 is disposed behind the handwheel 12. The speedometer 14 may be a light panel, for example with electroluminescent diodes. On figure 2, an obstacle 16 is located in front of the vehicle 2 on a road R and is schematically represented by a parallelepipedic block. In practice, the obstacle 16 is often another moving vehicle driven at a lower speed.

A method to prevent from a collision between the vehicle 2 and the obstacle 16 is detailed here-below, in reference to figures 3 and 4. On figure 4, rhombus-shaped boxes are comparison steps while rectangular boxes are action steps. The letters "Y" mean that the result of the comparison is positive, as for "YES".

A first step of the method consists in assessing whether the vehicle 2 is too close to the front obstacle 16 in function of the distance d between the vehicle 2 and the obstacle 16 and of the speed S of the vehicle 2. To this end, as shown on figure 5, the vehicle 2 is equipped with a sensor 32 for measuring the speed S of the vehicle and with a distance radar 34 for evaluating the distance d between the vehicle 2 and the front obstacle 16. The vehicle 2 comprises an electronic command unit (ECU) that collects the speed from the sensor 32 and the distance d from the radar 34 and that determines if the vehicle 2 nears the obstacle 16 too fast. The ECU further assesses the risk of a collision with the obstacle 16.

Instead of measuring an absolute speed of the vehicle 2, the speed of the vehicle 2 that is taken into account can be a relative speed of the vehicle 2 to the obstacle 16. Such evaluation of the relative speed is particularly useful to increase the reliability of the method when the front obstacle 16 is a preceding vehicle driven at a lower speed. Speed of the preceding vehicle 16 can be evaluated by a navigation system (not represented) integrating, for instance, an electronic horizon module. The navigation system or the ECU computes the relative speed by comparing speed of the vehicle 2 with speed of the preceding vehicle 16. When the vehicle 2 is closed enough to the preceding vehicle 16 the relative speed can be calculated via the distance radar 34 calculating a variation of distance d at two different times.

For instance, if the distance d between the vehicle 2 and the obstacle 16 is inferior to a first distance d1 and superior to a second distance d2 that is inferior to the first distance d1 and if the speed S of the truck 2 is superior to a first speed threshold value S1 , then, in a step 100, a first braking intensity level L1 is determined by the ECU in function of the distance d between the vehicle 2 and the obstacle 16 and of the speed S of the vehicle. In the example, d1 and d2 are equal respectively to 100 m and 80 m and S1 is equal to 70 km/h. The first braking intensity level L1 can be determined to sufficiently decelerate the vehicle 2 to avoid collision with the front obstacle 16. Alternatively, first braking intensity level L1 can be determined to decelerate the vehicle down to the first speed threshold value S1 and within a distance that is preferably inferior to 30 m depending on the weight and the initial speed of the vehicle 2.

In a step 200, it is determined and adapted by the ECU a first alert signal in function of the first braking intensity level L1 already determined by the ECU.

In a step 300, the first alert signal is emitted in the cabin of the truck 6 to alert the driver that the vehicle is too close from the front obstacle 16 and to inform him about the braking intensity level L1 that the braking system BS of the vehicle 2 is about to automatically apply. Following the emission of the first alert signal, the driver may push the pedal brake to slow down the vehicle 2 or let the vehicle being automatically slowed down by automatic application of the brakes according to a step 400. The alert signal such as determined and adapted in step 200 and such as emitted at step 300 can be a light signal, which is, for instance, outputted by means of the speedometer 14. For instance, this light signal may be outputted by turning on the backlight of the speedometer 14. The backlight of the speedometer 14 may be of red color to draw the attention of the driver.

If the vehicle has not been sufficiently decelerated to avoid collision or has not been decelerated manually under the first speed threshold value S1 after a first period of time t1 has lapsed since the triggering of step 300, the first braking intensity level is automatically applied at a step 400 to decelerate the vehicle. The first alert signal is applied during the first period of time t1 and can be maintained during the automatic braking phase 400 of the vehicle 2, that is to say during the phase where braking is automatically applied by the brake system BS of the vehicle 2. In a variant the first alert signal can be switched off as soon as the vehicle has started to automatically apply the brakes to decelerate the vehicle. Typically, this period of time t1 varies between 3 and 10 seconds and can be, for instance, 6 seconds. The first braking intensity level L1 consists in the application of a slight braking effort, that can be about 10% of the maximum capacity of the brakes. It allows relieving the driver when driving on roadways or speedways.

If the distance d between the vehicle 2 and the obstacle 16 is inferior to the second distance d2 and superior to a third distance d3 that is inferior to the second distance d2 and if the speed S of the truck 2 is superior to a second speed threshold value S2 that is inferior to the first speed threshold value S1 , then, in a step 102, a second braking intensity level L2 is determined by the ECU in function of the distance d between the vehicle 2 and the obstacle 16 and of the speed S of the vehicle. In the example, the third distance d3 is equal to 50 m and the second speed threshold value S2 is equal to 50 km/h. The second braking intensity level L2 can be determined to sufficiently decelerate the vehicle 2 to avoid collision with the front obstacle 16. Alternatively, the second braking intensity level L2 can be determined to decelerate the vehicle down to the second speed threshold value S2 and within a distance that is preferably inferior to 25 m depending on the weight and the initial speed of the vehicle 2.

In a step 202, it is determined and adapted by the ECU a second alert signal in function of the second braking intensity level L2 already determined by the ECU.

In a step 302, the second alert signal is emitted in the cabin of the truck 6 to alert the driver and to inform him about the braking intensity level L2 that the braking system BS of the vehicle 2 is about to automatically apply. For instance, a beep is turned on at step 302. This beep can be in addition to the light signal outputted at step 300. The beep is outputted by means of a loudspeaker 15 integrated in the cabin of the vehicle 2. This loudspeaker 15 is schematically represented on figure 3 by an audio icon. According to the determination and adaptation performed at step 202, at step 302, the beep can be emitted with an intensity of 20 dB and a frequency of 50 Hz. Moreover, the new light signal emitted at step 302 may be modified at step 202 by the ECU and may be different from the light signal emitted at step 300. For example, the backlight of the speedometer 14 may start to blink or its lighting may be intensified. In this way, the driver knows that the risk of collision with the front obstacle 16 is higher and that the braking intensity level L2 that the braking system BS of the vehicle 2 is about to automatically apply will higher than the braking intensity level L1.

If the vehicle has not been sufficiently decelerated to avoid collision or has not been decelerated manually under the second threshold value S2 after a second period of time t2 has lapsed since the triggering of step 302, the second braking intensity level L2 is automatically applied at a step 402 to decelerate the vehicle. The second alert signal is applied during the second period of time t2 and can be maintained during the automatic braking phase 402 of the vehicle. Typically, this period of time t2 is shorter than the first period of time t1 and varies between 0, 1 s and 5 s and can be, for instance, of 2s. The second braking intensity level L2 may consist in the application of a braking effort of about 20% of the maximum capacity of the brakes.

If the distance d between the vehicle 2 and the obstacle 16 is inferior to the third distance d3 and superior to a fourth distance d4 that is inferior to the distance d3 and if the speed S of the vehicle 2 is superior to a third speed threshold value S3 that is inferior to the second speed threshold value S2, then, in a step 104, a third braking intensity level L3 is determined by the ECU in function of the distance d between the vehicle 2 and the obstacle 16 and of the speed S of the vehicle. In the example, the third speed threshold value S3 is equal to 30 km/h and the fourth distance d4 is equal to 20 m. The third braking intensity level L3 can be determined to sufficiently decelerate the vehicle 2 to avoid collision with the front obstacle 16. Alternatively, the third braking intensity level L3 can be determined to decelerate the vehicle down to the third speed threshold value S3 and within a distance that is preferably inferior to 15 m depending on the weight and the initial speed of the vehicle 2.

In a step 204, it is determined and adapted by the ECU a third alert signal in function of the third braking intensity level L3.

More precisely, in step 204 the ECU can adapt the third alert signal such that the intensity of the beep that is emitted at step 304 is increased up to 50 dB and the frequency of the beep is increased up to 75 Hz. In addition, the light signal emitted by the speedometer 14 may also be modified by increasing the blinking frequency and/or its lighting.

If the vehicle has not been sufficiently decelerated to avoid collision or has not been decelerated manually under the third threshold value S3 after a third period of time t3 has lapsed since the triggering of step 304, the third braking intensity level L3 is automatically applied at a step 404 to decelerate the vehicle. The third alert signal is applied during the third period of time t3 and can be maintained during the automatic braking phase 404 of the vehicle. Typically, this period of time t3 is shorter than the second period of time t2 and varies between 0, 1 s and 2s and can be, for instance, of 1 second. The third braking level L3 may consist in the application of a braking effort of about 50% of the maximum capacity of the brakes. Finally, If the distance d between the truck 2 and the obstacle 16 is inferior to the fourth distance d4 and if the speed S of the truck 2 is superior to a fourth speed threshold value S4 that is inferior to the second speed threshold value S3 and that is preferably equal to 0 km/h, then, in a step 106, ECU determines that brakes have to be applied with a full capacity L4 and send a corresponding signal E1 to the brake system BS of the vehicle.

The brakes are applied at full capacity L4 during a step 406 since, it corresponds to a situation with a high risk of collision. This situation may occur when the obstacle 16 suddenly stops or when the front obstacle 16 is crossing the trajectory of the truck 2. In this case, the brake are applied so as to stop the vehicle 2.

In parallel, a fourth alert signal is adapted at a step 206 and emitted at step 306 to alert the driver. At step 206 the ECU can adapt the fourth alert signal such that the intensity of the beep that is sent to the driver in step 306 can be increased up to 1 10 dB and the frequency of the beep can be increased up to 100 Hz. This signal does not aim at stimulating the driver to brake manually the vehicle since the brake is already applied at full capacity. The braking intensity is adapted in a discrete manner and is selected by the electronic control unit ECU, in the above example, amongst four levels.

The values d1 to d4 and S1 to S4 are stored in a memory 31 of the electronic control unit ECU. The comparison steps described above can be all performed by the same electronic control unit ECU that can also control the braking system BS of the vehicle 2 and the backlight of the speedometer 14. The ECU determines 100, 102, 104, 106 the braking intensity that has to be automatically applied in function of the distance d between the vehicle 2 and the obstacle 16 and of the speed S of the vehicle 2. During steps 200, 202, 204 and 206, the ECU determines an alert signal in function of the braking intensity that it has previously determined. The alert signal is adapted by modifying, for instance, the intensity of the backlight to be outputted by the speedometer 14 of the vehicle and/or by modifying the blinking frequency of the backlight.

The electronic control unit ECU sends a signal E2 to the speedometer 14, this signal E2 depends on the intensity of the backlight to be outputted and of the blinking frequency of the backlight. The electronic control unit ECU can also pilot the loudspeaker 15 to modify the frequency and the intensity of the beep. The signal sent by the electronic control unit ECU to the loudspeaker 15 is represented on figure 5 by an arrow E3.

The alert signals sent after steps 200, 202 and 204 aim at informing the driver that an automatic brake is about to be applied. Consequently, the driver is not surprised and does not panic. This allows reducing the risk of an accident. At steps 400, 402, 404, the ECU sends a control signal E1 to the braking system BS of the truck 2 in order to automatically apply the brakes.

In the preceding example, the speed S and S1 to S4 refer to an absolute speed of the vehicle 2 regardless whether the front obstacle 16 is stop or moving. As previously explained, S and S1 to S4 can advantageously refer to a relative speed of the vehicle 2 to the speed of the obstacle 16 wherein the speed of the vehicle 2 is higher than the speed of the obstacle 16 and wherein the speed of the obstacle 16 can be null. In this case S1 to S4 can take the following values : S1 = 50 km/h; S2 = 30 km/h, S3 = 10 km/h and S4 = 0 km/h. Brakes are automatically applied with a brake intensity level that is determined by the ECU to decelerate the vehicle 2 to reach a zero relative speed before reaching the front obstacle 16.

It is to be understood that the present invention is not limited to the embodiments described above and illustrated in the drawings; rather, the skilled person will recognize that many changes and modifications may be made within the scope of the appended claims.

For instance, more or less braking intensity levels may be implemented.

In a non-represented alternative embodiment of the method, the braking intensity may evolve in a continuous manner depending on the distance with a front obstacle and on the speed of the vehicle 2.

In another non-represented alternative embodiment of the method, the throttle T of the vehicle 2 is jammed when the vehicle is nearing the obstacle 16 too fast. This corresponds to an "eco-fuel" driving mode.

The above numerical values, especially d1 to d4, S1 to S4 and L1 to L4, are chosen as an example and they may vary depending on the braking distance of the vehicle 2.

For instance, if the load of the vehicle 2 can be determined and taken into account by the ECU, higher is the load of the vehicle 2, higher will be the braking intensity level L1 , L2, L3 or L4 that has to be applied to slowdown the vehicle 2 down to the next lower threshold speed value or to avoid a collision with the front obstacle 6.

In another non-represented alternative embodiment, the distances d1 to d4, the speed threshold values S1 to S4 and the braking intensity levels L1 to L4 are updated by the electronic control unit ECU in function of the current vehicle speed, the distance d between the vehicle 2 and the front obstacle 16, the slope of the road and/or of weather conditions. Besides, the technical features of the different embodiments and alternative embodiments of the invention described here-above can be combined together to generate new embodiments of the invention.

Claims

1 .- Method to prevent from a collision between a vehicle (2) and a front obstacle (16), comprising the following steps consisting in:

a) assessing whether the vehicle (2) is too close to the front obstacle (16) in function of the distance (d) between the vehicle (2) and the front obstacle (16) and of the speed (S) of the vehicle (2),

characterized in that if the vehicle is too close to the front obstacle (16) the method includes the steps consisting in :

b) determining (100, 102, 104, 106) a braking intensity in function of the distance (d) between the vehicle (2) and the obstacle (16) and of the speed (S) of the vehicle,

c) determining (200, 202, 204, 206) an alert signal that is function of the braking intensity determined at step b),

d) emitting (300, 302, 304, 306) in the vehicle (2) the alert signal determined at step c) in order to alert the driver,

e) automatically braking (400, 402, 404, 406) the vehicle (2) with the braking intensity determined at step b).

2.- Method according to claim 1 , characterized in that the braking intensity is determined depending on the speed (S) of the vehicle (2) relative to the obstacle (16).

3. - Method according to claim 1 or 2, characterized in that the braking intensity is determined depending on the slope of the road (R), the load of the vehicle (2) and/or on weather conditions.

4. - Method according to any previous claim, characterized in that the alert signal includes a light signal, whose intensity and/or flashing frequency is adapted at step c).

5.- Method according to any previous claim, characterized in that the alert signal includes a beep, whose intensity and/or frequency is adapted at step c).

6.- Method according to any previous claim, characterized in that it includes a supplementary step that consists to jam the throttle (T) of the vehicle (2) when the latter is too close to the front obstacle (16).

7. - Method according to any previous claim, characterized in that the braking intensity is adapted in a discrete manner.

8. - Method according to claim 7, characterized in that the braking intensity is selected among at least three braking intensity levels (L1 , L2, L3, L4).

9. - Method according to claim 8, characterized in that at least the two first braking intensity levels (L1 , L2, L3) aim each at decelerating the vehicle (2) down to a speed threshold value (S1 , S2, S3) and the last braking level (L4) aims at stopping the vehicle.

10- Method according to any previous claim, characterized in that the alert signal is emitted at steps (300, 302, 304, 306) before automatically braking the vehicle (2).

11- Method according to the previous claim, characterized in that the alert signal is maintained during automatic braking (400, 402, 404, 406) of the vehicle (2).

Vehicle (2), comprising :

- detecting means (34) and an electronic control unit (ECU, 32) to

whether the vehicle is too close to a front obstacle (16),

an electronic control unit (32) for :

• determining the braking intensity in function of the distance (d) between the vehicle (2) and the obstacle (16) and of the speed (S) of the vehicle

• generating a control signal (E1) to trigger an automatic braking in function of the determined braking intensity,

• determining an alert signal in function of the determined braking intensity,

- a brake system to activate brakes of the vehicle (2) in function of the generated control signal (E1 ),

means (14, 15) for emitting the determined alert signal in the vehicle (2) in order to alert the driver.