WO2009061240A1

WO2009061240A1 - A vehicle safety system

Info

Publication number: WO2009061240A1
Application number: PCT/SE2007/050817
Authority: WO
Inventors: Katarina Bohman
Original assignee: Autoliv Development Ab
Priority date: 2007-11-05
Filing date: 2007-11-05
Publication date: 2009-05-14

Abstract

A vehicle safety system comprising a crash sensor (9), for determining whether the vehicle has been involved in a crash situation; a force sensor (7), for sensing the force applied to a safety belt (2) of the vehicle; a control unit (8) operable to evaluate information output by the force sensor (7) following a crash event, and to make a determination as to whether the information is indicative of chest activity of a vehicle occupant ( 1) wearing the safety belt (2); and a transmitter (15) operable to transmit a signal following a crash event, the signal including information output by the force sensor (7), or information relating to the determination made by the control unit (8).

Description

Title: A Vehicle Safety System

Description of Invention

This invention relates to a vehicle safety system, and in particular concerns an arrangement for transmitting information from a motor vehicle to an emergency centre after the vehicle has been involved in an accident.

After a vehicle has been involved in a crash or other accident, it is known to transmit information from the vehicle to an emergency centre. This information may include the location of the vehicle (determined by an on-board positioning system such as GPS), as well as information from crash sensors that were activated during the event and the number of occupants of the vehicle. !t has also been proposed to sense information regarding the bodily activity of the vehicle occupants, in order that a determination can be reached as to the injuries that the occupants may have sustained, and an example of such a system is shown in U S6166656. In this document, sensors are embedded in one of more seats of the vehicle, which are operable to sense the body temperature, blood pressure or pulse of an individual in the seat. This information can also be transmitted to an emergency centre following an accident.

It is an object of the present invention to seek to provide an improved safety system arrangement of this type.

Accordingly, one aspect of the present invention provides a vehicle safety system comprising a crash sensor, for determining whether the vehicle has been involved in a crash situation; a force sensor, for sensing the force applied to a safety belt of the vehicle; a control unit operable to evaluate information output by the force sensor following a crash event, and to make a determination as to whether the information is indicative of chest activity of a vehicle occupant wearing the safety belt; and a transmitter operable to transmit a signal following a crash event, the signal including information output by the force sensor, or information relating to the determination made by the control unit.

Advantageously, the determination made by the control unit relates to heart activity of the occupant.

Preferably, the determination made by the control unit relates to breathing activity of the occupant,

Conveniently, the belt force sensor is located in or on a buckle or other retainer which is adapted to receive and retain part of the safety belt,

Advantageously, the system comprises a tensioner to apply additional force to the safety belt following the crash.

Preferably, the tensioner is operable to apply additional force to the safety belt to improve engagement between the safety belt and the chest of the occupant, so that chest activity of the occupant can be detected more readily.

In order that the present invention may be more readily understood, embodiments thereof will now be described, by way of example, with reference to the accompanying drawings, in which:

Figure 1 shows a schematic view of components of a system embodying the present invention; and

Figure 2 shows a block diagram of components of a system embodying the present invention. With reference firstly to Figure 1, a schematic view is shown of an occupant 1 of a vehicle seat. A safety belt, in the form of a seat belt 2, is provided, as is well understood in the art. The seat belt 2 extends from a retainer 3, which, in the embodiment shown, is mounted near the left hip of the occupant 1. The retainer 3 comprises a tεnsioner 4 which is operable to apply a retracting force to the seat belt 2, which operates to return the seat belt 2 to its rest position, and also serves to lock the seat belt 2 against further extension in the event of an accident, to minimise movement of vehicle occupants.

The tensionεr 4 may be an active pretensioner. As will be understood by those skilled in the art, if it is determined that the vehicle is likely to be involved in a crash of another hazardous situation, then the seal belt 2 may be pre-emptively locked against further extension, or additional force may be applied to the seat belt 2, to maintain the position of the seat occupant firmly in the seat. The additional force may be provided by igniting a pyrotechnic charge.

The seat belt 2 extends upwardly from the tensioner 4, and passes through a pillar loop 5, which is attached to, for example, the B-pillar (not shown) of the vehicle. In the example shown, the pillar loop 5 is located near the left shoulder of the occupant 1. The seat belt 2 can be pulled across the chest of the occupant 1 and attached, via a metal tongue (not shown), to a buckle 6, which is located by the right hip of the occupant 1. In this configuration, the seat belt 2 therefore extends diagonally across the occupant's chest.

The buckle 6 includes a force sensor 7, to sense the force applied to the seat belt 2 in a direction that would tend to pull the seat belt 2 away from the buckle 6.

The tensioner 4 and buckle 6 are both connected to a control unit 8. The control unit 8 is operable to generate a pretensioning signal, which is sent to the tensioner 4 to cause the tensionεr 4 to exert, an additional force to the seat belt 2, as discussed above. The force sensor 7 of the buckle 6 is operable to output information to the control unit 8 relating to the force that is applied to the seat belt 2 over time. It will be understood that the control unit 8 may comprise a single processor, or may comprise a plurality of processors, which need not necessarily be located in the same place.

One or more crash sensors 9 are also provided. As will be understood by those skilled in the art, the crash sensors 9 may take many forms, for instance including infrared, radar, lidar, impact sensors and/or skid sensors. The crash sensors 9 are operable to make a determination that the vehicle is likely to be involved in a crash or other hazardous situation, or indeed that a crash is occurring, or has occurred.

The vehicle is preferably further equipped with a number of safety devices 10, such as one or more airbags (not shown) and the tεnsioner 4 of the seat belt 2.

The vehicle is also equipped with a system to allow communication with an emergency centre, and preferabiy this communication is carried out using the GSM (global system for mobile communications) standard, although any other suitable form of communication may be used. As discussed above, once it has been determined that a vehicle has been involved in a crash situation, information may be transmitted from the vehicle to an emergency centre, and this information may include the location of the vehicle, the time of the crash, and also information regarding the crash sensors that were activated during the event.

Figure 2 shows a schematic view of components of a system embodying the present invention. The behaviour of the system before, during and after a crash will now be described.

Before the crash occurs, it may be detected by one or more of the crash sensors 9 that the crash is likely to occur, or appears to be unavoidable, as discussed above. Information from the crash sensors 9 is processed by a crash algorithm 1 1 , and if the crash algorithm 33 makes a determination thai a certain type of crash is likely or unavoidable then one or more air-bags 12 may be inflated to protect an occupant 3 of the vehicle. The tensioner 4 of the seal belt 2 may also be activated, to act as a pretensioner and thus brace the occupant I during the crash, Other safety devices 10 may also be activated.

In preferred embodiments, the additional force applied to the seat belt 2 lasts for a relatively brief time, so that the occupant 1 is protected during the crash itself, but the seat belt 2 is released shortly afterwards.

After a first delay, which may be imposed by first delay circuit 13 A, the tensioner 4 may exert a force on the seat belt 2, to pull the seat belt 2 more tightly around the chest of the occupant. This will he discussed in more detail below.

After a further delay, which may be imposed by a second delay circuit 13B, the control unit 2 causes the generation of an emergency signal, which can be transmitted to an emergency centre. The signal is generated by an emergency signal generator 14, which may include in the signal some or all of the information from the crash sensors, the outputs of the crash algorithm 1 1 , and also information as to whether the air-bag 12 was activated, the seat belt tensioner 14 was activated and subsequently deactivated, or regarding any other safety systems of the vehicle. The signal produced by the signal generator 14 may also include the location of the vehicle, as determined, for example by an on-board GPS unit (not shown).

After the crash has finished, information from the force sensor 7 of the buckle 6 is also passed to the signal generator 14.

It has been found that, if the force sensor 7 is sufficiently sensitive, variation in the signals output by the force sensor 7 can be used to determined chest activity of the occupant 1 , and in particular breathing and heart activity of the occupant 1. If the seat belt 2 makes an appropriate contact with the occupant's chest, then as the occupant 1 breathes in, an additional force will be exerted on the seat belt 2, which can be detected by the force sensor 7, As the occupant breathes out again, the force will drop. In trials, it has been found that the variation in force exerted on the seat belt 2 may vary by at least 2,5 N. Depending upon the physiology of the individual occupant and the positioning of the seat belt on the occupant^'s body, variations of around 5 N, 7.5 N or 10 N may be detected.

The variation in the force exerted on the seat bell the result of the heart beat of the occupant 1 is likely to be less, but if the force sensor 7 is sufficiently sensitive then these variations can readily be detected. Typically, the force variations resulting from an individual's heart beat are around 10% of these due to breathing activity, i.e. from around 0.25 N to around 1 N.

Following a crash, the position of the occupant 1 and also the position of the seat belt 2 on the body of the occupant 1 may vary considerably, and hence the actual force exerted on the seat belt after a crash may vary considerably from one particular crash to another. However, the difference between the maximum and minimum force exerted on the seat belt, as well as the length of time between consecutive maxima, should make it possible to determine whether the occupant is still displaying breathing activity, and heart activity, following a crash. In particular, variations in force arising from breathing are likely to be more gradual and to take place from around 10 times per minute (for a calm and healthy person) to around 30 times per minute (for an injured and/or stressed person). By- contrast, variations in force arising from an occupant's heartbeat are likely to be sharper and to take place at intervals of around one second or less. Generally, heart beats will always occur at a higher frequency than breathing activity,

In preferred embodiments, the control unit 8 is operable to analyse the signals output by the force sensor 7 to make a determination as to whether the signals are indicative of breathing or heart activity. The control unit 8 may output at least one value representing the occupant's chest activity. This value may, for instance, be a simple indication that the occupant is breathing, or that heart activity, or both. The value may alternatively be indicative of the variations in force applied to the seat belt 2 over time, and/or to the rate of breathing or heart activity. The skilled person will realise that the at least one value may take many different forms. information from the belt force sensor 7, or information derived from the output of the belt force sensor 7 (for instance, the value determined by the control unit 8), is therefore included in the signal that is produced by the signal generator 14. In certain embodiments, the information from the force sensor 7 is included in the signal only if it is determined by the control unit 8 that the information is indicative of chest activity. The signal is passed from the signal generator 14 to a transmitter 15, which then transmits the signal to an emergency control centre.

Advantageously, following the relaxation of the seat belt 2 after the crash, further tension is applied to the seat belt 2 to draw the seat belt 2 more tightly around the chest of the occupant 1, in order that chest activity of the occupant 1 may be detected more readily. In these embodiments, immediately after the crash, the variations in the force detected by the force centre 7 may be analysed, to see if evidence of chest activity can be found. If no appropriate variations are detected, then the tension applied to the seat belt 2 by the tensioner 4 is increased, in the hope that this will bring the seat belt 2 into closer contact with the occupant's chest, so that the chest activity can be detected. If appropriate variation in force is detected, further tensioning of the seat belt 2 is halted.

If, as a result of the initial tensioning, the force applied to the seat belt 2 exceeds a predetermined limit, further tensioning of the seat belt 2 is stopped — failure to detect variations in the force applied to the seat belt 2 may indicate that the seat belt 2 is no longer in position over the chest of the occupant 1, or that there is no detectable chest activity. In either case, increasing the tension in the seat belt 2 beyond a certain limit may cause or aggravate injuries to the occupant 1.

It will be understood that the ability to transmit information regarding the chest activity to the emergency control centre may be invaluable in ensuring that emergencies are prioritised correctly, and that appropriate medical personnel are dispatched to deal with particular events. The present invention provides a simple and effective way of achieving this, using components that are already installed in many motor vehicles. When used in this specification and claims, the terms "comprises" and "comprising" and variations thereof mean that the specified features, steps or integers are included. The terms are not to be interpreted to exclude the presence of other features, steps or components.

The features disclosed In the foregoing description, OF the following claims, or the accompanying drawings, expressed in their specific forms or in terms of a means for performing the disclosed function, or a method or process for attaining the disclosed result, as appropriate, may, separately, or in any combination of such features, be utilised for realising the Invention in diverse forms thereof.

Claims

1. A vehicle safety system comprising: a crash sensor (9), for determining whether the vehicle has been involved in a crash situation; a force sensor (7), for sensing the force applied to a safety belt (2) of the vehicle; a control unit (8) operable to evaluate information output by the force sensor (7) following a crash event, and to make a determination as to whether the information is indicative of chest activity of a vehicle occupant (1) wearing the safety belt (2); and a transmitter (15) operable to transmit a signal following a crash event, the signal including information output by the force sensor (7), or information relating to the determination made by the control unit (8).

2. A system according to claim 1 , wherein the determination made by the control unit (8) relates to heart activity of the occupant (1).

3. A sensors according to claim 1 or claim 2, wherein the determination made by the control unit (8) relates to breathing activity of the occupant (1).

4. A system according to any preceding claim, wherein the belt force sensor (7) is located in or on a buckle (6) or other retainer which is adapted to receive and retain part of the safety belt (2).

5. A system according to any preceding claim, comprising a tensioner (4) to apply additional force to the safety belt (2) following the crash.

6. A system according to claim 5, wherein the tensioner (4) is operable to apply additional force to the safety belt (2) to improve engagement between the safety belt (2) and the chest of the occupant (1), so that chest activity of the occupant (1) can be detected more readily. fO

7. A safely system substantially as hereinbefore described, by way of example, with reference to the accompanying drawings.

8. Any novel feature or combination of features disclosed herein.