Technical field

The present disclosure relates to a system for protecting a user's head in case of an abnormal movement, such as a fall or a collision. More specifically, the present invention relates to a wearable airbag for protecting the head of a bicyclist in case of an accident when biking.

Background

Airbags for the protection of a person's head are known in the art, for example through WO2012044245. As opposed to vehicular airbags the airbag of

WO2012044245 is designed to inflate into a complex head protecting shape. The airbag is designed as a double-bag construction, of which the inflated helmet-shape of the inner plastic bag is formed by the finger like construction of the outer bag.

The airbag mentioned in WO2012044245 is designed to detect if the user is exposed to an abnormal movement, such as a fall or a collision, for a specific activity, for example riding a bicycle. For the airbag to protect the user during an accident, the user has to correctly wear the airbag when doing the specific activity. During the activity the wearable airbag is activated, constantly monitoring the movements of the user. As inflation is controlled by comparing the current movement with reference movements of the particular type of activity, it is important to turn off the wearable airbag once the type of activity is changed, e.g. from cycling to walking or running. Compared to traditional helmets the wearable airbag is so gently arranged around the neck that a user may not want to remove the airbag when doing an activity other than the indented. There is thus a need for an airbag that eliminates or at least mitigates problems arising from this situation.

Summary

An object of the present invention is to provide a new type of airbag system which is improved over prior art and which eliminates or at least mitigates the drawbacks discussed above. More specifically, an object of the invention is to provide an airbag system that has an improved locking device in which the user can decide if the airbag system is to be put in an active or passive state.

In a first aspect the airbag system for protecting a body part of a user in case of an accident is provided. The airbag system comprises an airbag arranged as a collar, wherein said collar comprises interlocking means arranged to connect the ends of the collar, wherein said interlocking means comprises a first fastening body and a second fastening body, and wherein the interlocking means is configured to be selectively arranged in a first locking position or a second locking position when said first fastening body and said second fastening body are connected to each other.

In one embodiment, the system further comprises a control unit configured to put the airbag system in an idle state when the interlocking means is the a first locking position, and put the airbag system in an active state when the interlocking means is in the second locking position.

The control unit may further be configured to alert the user that the idle state is activated when the interlocking means is in the first locking position, and alert the user that the active state is activated when the interlocking means is in the second locking position.

In one embodiment the second fastening body comprises a top portion which is configured to selectively be put in a first position or a second position. The top portion may comprise a first top portion and a second top portion.

When the interlocking means is arranged in the first locking position, the top portion may be arranged in the first position. The top portion may be arranged in the first position when the first top portion and the second top portion are at least partly separated from each other.

Brief description of the drawings

The present invention will hereinafter be further explained by means of non- limiting examples with reference to the appended schematic figures where;

Fig. la is a schematic view of a user wearing an inflatable helmet, including an airbag system according to some embodiments; Fig. lb is a schematic view of a user wearing an inflated helmet, including an airbag system according to some embodiments;

Figs. 2a-c are schematic views of different resting positions according to different embodiments;

Fig. 3 is a schematic view of an airbag system according to an embodiment;

Figs. 4a-e are schematic views of a locking device according to a first embodiment; and

Figs. 5a-f are schematic views of a locking device according to a second embodiment; and

Figs. 6a-c are schematic views of a locking device according to a third embodiment.

Detailed Description

The airbag system described herein is configured to be used to detect an accident, such as a fall or collision, for example for when a user is riding a bicycle. The airbag system is thus configured for the specific use of riding a bicycle, i.e. cycling is the intended activity of the airbag system. For the airbag system to protect the user during an accident, the user has correctly to wear the airbag system and have it turned on in an active state. It would thus be preferred to provide a system that has an improved locking device to ensure a correct fit of the airbag to the user and which allows for different locking positions having different purposes (e.g. turned off, turned into an idle ON-state, or active ON-state).

Furthermore, having the airbag system set in an activate ON-state when the user is not doing the intended activity, e.g. not cycling, results in an undesirable energy loss since the airbag system is in an active state using battery power to power a sensor(s) and to process the movement data gathered therefrom, although there is no risk for a fall or collision.

It would thus be beneficial if the computational demanding determination, if a user is about to fall or collide when doing the indented activity, e.g., riding a bicycle, is deactivated when it's not needed so as to reduce the overall energy consumption of the system. The system may determine if the airbag system is needed, in particular if a user is actually performing the intended activity or not. This information may for example be used to change the mode of the airbag system 100.

Additionally, or alternatively, to having a system that determines if the airbag system is to be in an active ON-state or an idle state it is beneficial if the user can determine if he/she wants to have the airbag system in an idle or active state. This is achieved by an airbag system that has an improved locking device in which the user can decide if the airbag system is to be put in an active or passive state as will be described more herein.

Fig. la shows an airbag system 100 according to an embodiment in its non- inflated state. The airbag system 100 forms an apparel having the shape of a collar 10 which is worn around the neck 2 of a user 3. Upon inflation, the apparel transforms into an inflated helmet.

The collar 10 is placed around the neck 2 of the user 3 and has for that purpose a sealable opening, normally at the front of the collar 10. Alternatively, the opening may be arranged at the back of the collar 10 or at the shoulder portion of the collar 10.

Furthermore, the opening may be totally or partly dividable. The opening is sealed using interlocking means 30 to connect the ends of the collar 10 e.g. adjacently the user's 3 throat or neck region. The interlocking means 30 facilitates easy dressing and undressing of the collar 10 on the user 3. Furthermore, the position of the different parts of the interlocking means 30 determines if the airbag system 100 is turned on (i.e. having power) or turned off, and if its turned on in an active state or in an idle state. The interlocking means 30 and the active and idle state will be described more in detail with reference to Figs. 4a-f and Figs. 5a-c.

The collar 10 may be made of any kind of flexible material, such as acetate silk, jeans, fleece, cotton, beaver nylon or any other suitable fabric

When the airbag system is not worn by the user, the collar 10 can be put in a resting position to allow the user to carry the collar 10 easier for example by putting it in a bag. All electronics in the airbag system is turned off when the airbag system is put in the resting position. In the resting position the collar is connected such that the diameter of the collar is greatly reduce as is shown in the exemplary embodiments in Figs. 2a-c. This prevents the user from being able to have the collar 10 arranged around the neck when the collar is in its resting position. This resting or carrying position is beneficial if the user 3 is not doing the intended activity, but still wants to carry around the airbag system for practical reasons. If the intended activity is riding a bicycle, the user 3 may for example put the airbag system 100 in a resting position when he/she is entering a store to do some shopping before riding the bicycle again.

Three different resting positions are shown in Figs. 2a-c, where the diameter of the collar is reduced by connecting different parts of the collar 10 by connecting means 11. The connecting means 11 may be zippers, buttons, Velcro fastening, magnets, hooks, hanks, buckles, safety pins, straps or the like. The collar 10 may for example be arranged in a spiral shape (as in Fig. 2a), in a bottle-shape (as in Fig. 2b) or in a heart shape (as in Fig. 2c).

The collar 10 comprises a folded airbag 15 which is inflated to form a helmet for protecting the head of the user 3 in case of an abnormal movement, e.g. during a cycling accident.

An inflated helmet is schematically shown in Fig. lb. Here, the collar 10 is opened to release the airbag 15 previously enclosed therein. The airbag 15 surrounds the neck 2 and the head 4 of the user 3 and provides an efficient protection for the user 3.

The airbag 15 is formed by a flexible material in order to be folded and stored within the collar 10 prior to inflation. The airbag 15 may e.g. comprise an inflatable inner bag surrounded by an outer bag. Inflation of the inner bag leads to expansion of the outer bag and the structure of the outer bag defines the shape of the airbag when the inner bag is inflated. Although not shown in Fig. la and b, the airbag system may also be an one-bag construction.

The inner bag may be made of a fluid impermeable material, such as thermoplastic polyurethane film. Since fluid cannot easily leave a fluid impermeable bag, a person wearing an airbag 15 according to the invention will be protected by said airbag 15 for some time after expansion of the airbag 15, effectively protecting the head of the user for the entire time of the accident. The inner bag may be flexible and expandable such that it may expand the outer bag upon inflation to a high pressure. Hence, the inner bag may be inflated resulting in a relatively high internal pressure which preferably is maintained for a required time. An example of how the inner and outer bag may be configured is described in WO2012044245 by the same applicant.

As shown in Fig. 3, the airbag system 100 further comprises at least one sensor 80 for detecting movement of the collar 10, i.e. movement of the user 3 during use, and a control unit 50 configured to in response to the information gained by the sensor 80 determine if the movement corresponds to an accident situation. If an accident situation is determined, the control unit 50 will trigger inflation of the airbag 15 by means of an inflation device 60. The airbag system 100 further comprises a power source 70, for example a rechargeable battery or a disposable battery, in order to provide electricity to the parts of the system 100. The different parts will now be described more in detail.

The inflation device 60 may be any suitable type of airbag inflation device, such as a hybrid generator using a combination of compressed gas and solid fuel, a pyrotechnic airbag inflator which uses hot gases formed by powder, a heated gas inflator, or a an inflation device using solid fuel. In an embodiment, the inflation device 60 is a cold gas inflator.

The inflation device 60 may further be provided with a gas guide 65, for directing the gas into the airbag. The inflation device 60 is clamped, screwed, glued, sewed or the like onto the textile bag and the gas guide 65 is positioned inside the textile bag for directing the gas into the bag for inflating the airbag in a proper manner. The gas guide 65 may be T-shaped for being able to lead the gas into the airbag in a suitable stable way. Alternatively the gas guide 65 may be Y- shaped, I-shaped, arrow-shaped, multiple-part shaped cylindrical shaped or the like.

The inflation of the airbag 15 is controlled by the control unit 50. The control unit 50 controls the inflation of the airbag in case of an abnormal movement and prevents the airbag system from inflation at an undesired occasion. The control unit 50 may be implemented using instructions that enable hardware functionality, for example, by using executable computer program instructions in a general-purpose or special- purpose processor that may be stored on a computer readable storage medium (disk, memory etc.) 52 to be executed by such a processor. The control unit 50 may be configured to read instructions from the memory 52 and execute these instructions to control the operation of the airbag system 100. The control unit 50 may be implemented using any suitable, publically available processor or Programmable Logic Circuit (PLC). The memory 52 may be implemented using any commonly known technology for computer-readable memories such as ROM, RAM, SRAM, DRAM, FLASH, DDR, SDRAM or some other memory technology.

The control unit 50 may be a dedicated control unit or the control unit may also be configured to control other functions.

The at least one sensor 80 collects data relating to the movement of the collar 10. The sensor 80 may e.g. be an accelerometer, a gyro, an air ultrasonic transducer, radar and/or a laser. In one embodiment at least one sensor 80 is an accelerometer measuring acceleration in three dimensions and/or the sensor 80 is a gyro detecting angular speed in three dimensions. Additionally, or alternatively, the at least one sensor 80 may be an air ultrasonic transducer, or any device using electromagnetic waves, that measures the distance from the ground to the collar.

EP2313814, filed by the same applicant, discloses a method for detecting a bicycle accident without falsely classifying any data samples from normal cycling activities as accident. The system classifies the detected movement into either a "normal class" relating to movement patterns representing riding a bicycle or doing related activities or into an "action class" relating to movement patterns representing a bicycle accident.

The movement data gathered from the at least one sensor 80 is transmitted to the control unit 50. The control unit 50 processes the data and analyses it in order to evaluate if the processed data corresponds to an accident situation.. If the data corresponds to pre-stored data indicating an accident situation, the control unit 50 transmits a triggering signal to the inflation device 60 to trigger the inflation of the airbag 15. The airbag 15 will consequently be inflated when the inflation device 60 receives the triggering signal.

The controller is coupled to the memory 52 which saves the measured and processed data. The saved data can be used to review and analyse the activity history of the airbag system. This is particularly useful if the airbag system has been deflated and technicians want to verify that the airbag system was working properly. If the user 3 wears the airbag system 100 when performing an activity for which the airbag system 100 was not intended, such as climbing or riding an elevator, there is a slight risk that the control unit 50 incorrectly detects the movement as an accident and triggers the inflation. In some embodiments, the system 100 may be configured to directly determine between when a user 3 is doing the intended activity, e.g. riding a bicycle, and when the user is doing an un-intended activity, such as climbing or running, and to subsequently alarm the user 3 if he/she is doing an unintended activity with the airbag system 100 and that the airbag system 100 should be turned off or turned into an idle state. In the following, the first activity state of the user 3 is the user 3 doing an un-intended activity. If the intended activity for the airbag system is riding a bicycle, the first activity state is the user 3 doing an activity other than riding a bicycle. The determination could either be done by determining if the user is doing the intended activity (e.g. bicycling), determining if the user is doing an unintended activity (e.g. activity other than bicycling) and/or determining both if the user is doing the intended activity or an unintended activity.

The determination of when a user 3 is in a first activity state is preferably done using movement data gathered by the airbag system 100. The movement data used to determine the activity state of the user (e.g. walking or bicycling) may be retrieved from the at least one sensor 80 and/or from at least one additional sensor 85. The control unit 50 is configured to receive the movement signal(s) and process the signal(s) to determine if it corresponds to a predetermine pattern indicating the first activity state.

The additional sensor 85 may be an accelerometer, a gyro, an air ultrasonic transducer, radar and/or a laser or any other suitable sensor. The movement signals used to determine the activity state of the user may comprise information relating to acceleration, angular speed and/or the distance from the ground to the collar.

Hence, when the airbag system is in an active or idle ON-state, the control unit 50 is configured to determine if the user 3 is in a first activity state not corresponding to the intended activity by processing the output from the at least one sensor 80, 85. If the control unit 50 detects that the user 3 is in a first activity state, the control unit 50 is configured to alert the user 3. The airbag system 100 may further comprise a user interface 95. The user interface 95 produces a signal detectable by the user, so as to alert the user 3 with different information. The user interface 95 may be configured to alert the user 3 to turn the airbag system 100 into an active/idle state or turn it off. The user interface 95 may also be configured to indicate the status of the airbag system, i.e. the battery level, if the battery is in need for change or charging, if the inner elements of the helmet is intact or not, and if the system is turned on. As will further be described with reference to the interlocking means shown in Figs. 4a-f and 5a-c, the user interface 95 may be used to alert the user 3 that the airbag system 100 is turned on in an idle state or turned on in an active state in response to changing the position of the parts of the interlocking means 30.

The alert signal could be in the form of an audible signal such as siren, a haptic signal such as a vibration, a visual signal such as a strobe light or other sensory alarm that could be arranged on a user in the form of an airbag system 100.

The user interface 95 may comprise one or a plurality of light emitting diodes

(LED), which indicate information using light signal(s). Different colors of the light or flashing signals may for example indicate different information. The user interface 95 may also comprise a speaker sending out a sound signal, such as a buzz, or a device sending out a vibrating signal or a spoken phrase.

As seen in Figs. 4a-e, a first embodiment of the interlocking means 30 comprising a first fastening body 31 and a second fastening body 32 arranged to connect the ends of the collar 10 is shown. One end of the first and second fastening body 31, 32 are each connected to the collar 10. The collar 10 is thus easily attached to the neck of the user by attaching the first fastening body 31 and the second fastening body 32 to each other, and the collar 10 is released from the neck of the user 3 by detaching the first and second fastening bodies 31, 32 from each other.

The second fastening body 32 has a hollow body with a cavity 33 arranged to receive and hold a protruding element 34 of the first fastening body 31. The second fastening body 32 further comprises a bottom portion 36 and a top portion 35. The top portion 35 is arranged above the bottom portion 36. The top portion 35 is arranged on the surface facing away from the neck of the user 3 when the airbag system is worn. The top portion 35 comprises a first top portion 35a and a second top portion 35b. As best seen in Fig. 4e, the second top portion 35b is arranged on top of the first top portion 35a. Preferably, the area of the second top portion 35b is smaller than the first top portion 35a so that at least a part of the first top portion 35a is visible for the user. The top portion 35 can be arranged in a first position (as in Fig. 4c), in a second position (as in Fig. 4d) and in a third position (as in Fig. 4b). In a first position, the second top portion 35b and the first top portion 35a are at least partly vertically separated from each other. The second top portion 35b is rotatably arranged in the bottom portion 36 and/or the first top portion 35b so that it is allowed to rotate between an opened and a closed state compared to the first top portion 35a. The opened state corresponds to the top portion 35 being in the first position. In a second position, the second top portion 35b and the first top portion 35a are arranged in proximity to each other. Both the second top portion 35b and the first top portion 35a are arranged in a closed state with reference to the bottom portion 36. Hence, the whole top portion 35 is in a closed state. In a third position, the second top portion 35b and the first top portion 35a are arranged in proximity to each other and both second top portion 35b and the first top portion 35a are arranged in an opened state with reference to the bottom portion 36. The top portion 35 is rotatably arranged in the bottom portion 36 so that it can rotate between the first, the second and the third position.

In the embodiment shown in Figs. 4a-e, the first fastening body 31 is a male connector and the second fastening body 32 is a female connector. Here, the

interlocking means 30 is in the form of a buckle and more specifically a side release buckle. The female connector 32 and the male connector 31 are released from each other by the user lifting the top portion 35a.

In Fig. 4a, the interlocking means 30 is in an open position, i.e. the first fastening body 31 and a second fastening body 32 are not connected to each other. This position should not be used when the user 3 is doing the intended activity, e.g. riding a bicycle, since the collar 10 is not properly arranged on the user 3.

Fig. 4b illustrates the interlocking means 30 in a state between an open position and a first locking position. In order for the user to be able to press the two fastening bodies 31, 32 together the top portion 35 needs to be arranged in a third position where the top portion 35 is opened.

Figs. 4c-d show the interlocking means in positions where the first fastening body 31 and the second fastening body 32 are connected to each other. The airbag system 100 is correctly arranged on the user 3, for example arranged around the neck of the user 3.

Fig. 4c shows the interlocking means in a first locking position. In the first locking position the male connector 31 and the female connector 32 are connected to each other but the protruding element 34 is not completely received in the cavity 33 of the second fastening body 32. Furthermore, the top portion 35 is arranged in a first position, where the first top portion 35a and the second top portion 35b are at least partly separated from each other.

When the top portion 35 turns into a first position, a first switch sensor (not shown) activates an electronic circuit arranged in the interlocking means 30. The first switch sensor may be a mechanical switch, a Hall sensor, an electronic switch, a electromechanically switch or any other sensor configured to determine if the male connector 31 and the female connector 32 are connected to each other and/or the top portion 35 is in a first position.

In one embodiment the first switch sensor detects light, magnetic flux, electricity, pressure, and/or another parameter in the interlocking means 30 and if the measured signal is greater than a threshold value, as would be the case when the male connector 31 and the female connector 32 are connected to each other and/or when the top portion 35 is in a first position, the sensor switches the circuit so as to put the interlocking means 30 in the first locking position.

In an alternative embodiment, the first switch sensor is a

mechanical switch and may comprise a mechanically biased rod member that is displaced when the male connector 31 and the female connector 32 are connected to each other and/or when the top portion 35 is in a first position. The rod member may be held in an assumed position by a spring or other resilient member.

Fig. 4d shows the interlocking means 30 in a second locking position. In the second locking position the male connector 31 and the female connector 32 are completely connected to each other so that the protruding element 34 is completely received in the cavity 33 of the second fastening body 32. Additionally, the top portion 35 is arranged in a second position. When the top portion 35 is in the second position, the first top portion 35a and the second top portion 35b are arranged in conjunction to each other and/or locked into each other so that the whole top portion 35 is in a closed state. In order to put the interlocking means 30 in the second locking position, starting from the first locking position, the second top portion 35b is moved downwards from the first position of the top portion 35 towards the first top portion 35a. When the second top portion 35b is arranged in conjunction to the first top portion 35a, a second switch sensor (not shown) activates an electronic circuit arranged in the interlocking means 30. The second switch sensor may be of the same type as the first switch sensors mentioned in conjunction to Fig. 4c. The second switch is configured to switch to a second locking position when the second top portion 35b is arranged close to the bottom portion 36 of the second fastening body 32.

Fig. 4e shows an exploded view of an interlocking means 30. The first fastening body 31 comprises a protruding element 34 which has a geometry, such as for example a hole 34a, arranged to receive a locking portion 35c arranged in the second fastening body 32. In order to be able to achieve movement of the different parts of the top portion 35, rotation means 37 are arranged on the bottom portion 36. The rotation means 37 may comprise a resilient member, such as a spring, that allows the top portion 35 to be moved between a position where the top portion is arranged in conjunction with the bottom portion 36 and a position where the top portion 35 is arranged at a distance from the bottom portion 36. Both the first top portion 35a and the second top portion 35b of the top portion 35 each comprises means 38 for receiving the rotation means 37 for allowing rotation in relation to the bottom portion 36.

Another embodiment of the interlocking means 20 is shown in Figs. 5a-f. The interlocking means 20 comprises a first fastening body 21 and a second fastening body 22. The first fastening body 21 comprising a protruding element 24 has the same function and structural composition as in the previously described embodiment. As in the previous embodiment the second fastening body 22 has a hollow body with a cavity 23 arranged to receive and hold a protruding element 24 of the first fastening body 21. The second fastening body 22 further comprises a bottom portion 26 and a top portion 25.

The top portion 25 can be arranged in a first position (as in Fig. 5c and d), in a second position (as in Fig. 5e) and in a third positon (as in Fig. 5b). When the top portion 25 is in a first position, the top portion 25 and the bottom portion 26 are arranged in conjunction to each other and/or the portions 25, 26 are locked into each other. In a second position the first top portion 25a and the second top portion 25b are separated from each other by a distance d. In the third position, the top portion 25 is opened, i.e. arranged at a distance from the bottom portion of the second fastening body 26.

In Fig. 5a, the interlocking means 20 is in an open position, i.e. the first fastening body 21 and a second fastening body 22 are not connected to each other. This position should not be used when the user 3 is doing the intended activity, e.g. riding a bicycle, since the collar 10 is not properly arranged on the user 3.

Fig. 5b illustrates the interlocking means 20 in a state between an open position and a first locking position. In order for the user to be able to press the two fastening bodies 21, 22 together the top portion 25 needs to be arranged in a third position where the top portion 25 is opened.

Figs. 5c-d show the interlocking means in a first locking position. In the first locking position the male connector 21 and the female connector 22 are completely connected to each other. Furthermore, the top portion 25 is in a first position. When the male connector 21 and the female connector 22 are completely connected to each other, the top portion 25 is configured to be turned into a first position. When the top portion 25 turns into a first position, a first switch sensor (not shown) activates an electronic circuit arranged in the interlocking means 20. The first switch sensor may be of the same type as the first switch sensors mentioned in conjunction to Figs. 4a-e. The first switch sensor may be a sensor configured to determine if the male connector 21 and the female connector 22 are completely connected to each other and/or the top portion 25 is in a first position.

Fig. 5e shows the interlocking means in a second locking position. In the second locking position the male connector 21 and the female connector 22 are still completely connected to each other and the top portion 25 is in a second position where the first top portion 25a and the second top portion 25b are separated from each other by a distance d. In order to put the interlocking means 20 in the second locking position, starting from the first locking position, the second top portion 25b is moved away from the first top portion 25a. When the second top portion 25b is at a distance d from the first top portion 25a, a second switch sensor (not shown) activates an electronic circuit arranged in the interlocking means 20. The second switch sensor may be of the same type as the first or second switch sensors mentioned in conjunction to the embodiment shown in Figs. 4a-e. The second switch is configured to switch to a second locking position when the second top portion 25b is arranged at a distance d from the first top portion 25a.

Fig. 5f shows an exploded view of an interlocking means 20. The first fastening body 21 comprises a protruding element 24 which has a hole 24a arranged to receive a locking portion 25c arranged in the second fastening body 22. In order to be able to achieve movement of the top portion 25 between a first and a second position, rotation means 27 are arranged on the top portion 25. The rotation means 27 may comprise a resilient member, such as a spring, that allows the top portion 25 to be moved between a position where the top portion is arranged in conjunction with the bottom portion 26 and a position where the top portion 25 is arranged at a distance from the bottom portion 26.

The second top portion 25b is arranged to be movable between two different positions, one position where it is in conjunction with the first top portion 25a and one position where it is arranged at a distance d from the first top portion 25a. This may be achieved by rails arranged on the sides of the second top portion 25b and/or having rails on the sides of the first top portion 25a.

The locking portion 25c is arranged on the bottom side of the top portion 25, facing the bottom portion 26 of the second fastening body 22. When the locking portion 25c is arranged in the hole 24a, the first fastening body 21 and the second fastening body 22 are completely attached to each other.

Yet another embodiment of the interlocking means 40 is shown in Figs. 6a-c.

The interlocking means 40 comprises a first fastening body 41 in the form of a male connector and a second fastening body 42 in the form of a female connector. The second fastening body 42 has a hollow body with a cavity 43 arranged to receive and hold a protruding element 44 of the first fastening body 41. The first fastening body 41 further comprises a top protruding element 44a. The second fastening body 42 further comprises a bottom portion 46 and a top portion 45. The top portion 45 comprises a first top portion 45a and a second top portion 45b, arranged in a side-by-side manner.

In Fig. 6a, the interlocking means 40 is in an open position, i.e. the first fastening body 41 and a second fastening body 42 are not connected to each other.

Fig. 6b shows the interlocking means in a first locking position. In the first locking position the male connector 41 and the female connector 42 are connected to each other. The protruding element 44 is received at least in part in the cavity 43 and the top protruding element 44a is arranged in the first top portion 45a. The position where the top protruding element 44a is arranged in the first top portion 45a is referred to as the top protruding element 44a being in a first position. When the top protruding element 44a is in a first position, a first switch sensor (not shown) activates an electronic circuit arranged in the interlocking means 40.

Fig. 6c shows the interlocking means in a second locking position. In the second locking position the male connector 41 and the female connector 42 are completely connected to each other. The protruding element 44 is fully received in the cavity 43 and the top protruding element 44a is arranged in the second top portion 45a. The position when then the top protruding element 44a is arranged in the second top portion 45b is referred to as the top protruding element 44a being in a second position. When the top protruding element 44a is in a second position, a second switch sensor (not shown) activates an electronic circuit arranged in the interlocking means 40.

Although the Figs. 4-6 show embodiments where the interlocking means 20;

30; 40 is a female and male connector, such as a buckle, it should be noted that the interlocking means also could also take another form as long as at least two locking positions could be achieved. Furthermore, the mechanics relating to the first and second locking position may differ. The different functions and benefits relating to having an interlocking means 20; 30; 40 according to the described embodiments in an airbag system 100 will now be described.

When the interlocking means 20; 30; 40 is in a first locking position, and the electronic circuit is activated by the first switch, the control unit 50 is configured to put the airbag system 100 in a first mode. Depending on configuration the first mode may pertain to different functions such as alerting the user 3 and/or configuring the airbag system 100 in an idle state.

In one embodiment the control unit 50 being in the first mode is configured to set the airbag system 100 in an idle ON-state. In the idle state the airbag systems 100 is powered up but other functions may be idle. Preferably, in the idle state the inflation functionality is disabled. Additionally, the determination between the normal activity state, such as riding a bike, and being in an accident, such as a fall or collision may be disabled. However, in idle state, the control unit 50 and a sensor 80, 85 used for determining the activity state of the user 3 may be active so as to determine if to alert the user 3 or not depending on the activity state of the user 3.

The idle ON-state, and thus the first locking position, is preferably used when the user 3 is not doing the intended activity. This has the benefit that it reduces the risk of incorrect inflation due to the user performing other actions (such as running, walking, jumping, etc.) than the intended action. Additionally, determining between the normal activity state, such as riding a bike, and being in an accident, such as a fall or collision, requires significant amount of data power whereas determining if the user 3 is in a first activity state (e.g. doing an unintended activity) may require less data power. It is thus possible to reduce the energy consumption of the airbag system 100 by putting the system in an idle ON-state when the user 3 has put the interlocking means 30 in a first locking position, thus indirectly indicating that he/she is not doing the intended activity.

In one embodiment, when the airbag system 100 is in a first mode, the control unit 50 is configured to set the airbag system 100 in an idle state and as an optional step, the system may also alert the user 3 that the state of the airbag system 100 has been changed to the idle state. In one embodiment, the control unit 50 being in a first mode is configured to alert the user 3. The control unit 50 may be configured to alert the user 3 by transmitting a signal to the user interface 95 which subsequently alerts the user 3. In this way the user 3 is alerted that the airbag system 100 is turned into an idle state.

When the interlocking means 20; 30; 40 is in a second locking position, the control unit 50 is configured to put the airbag system 100 in a second mode. Depending on configuration the second mode may pertain to different functions such as alerting the user 3 and/or configuring the airbag system 100 in an active state.

In one embodiment the control unit 50 being in the second mode is configured to set the airbag system 100 in an active ON-state. In the active state the inflation functionality is active and the system 100 determines between the normal activity state, such as riding a bike, and being in an accident, such as a fall or collision. Hence, in the active state all parts of the airbag system 100 are active and the airbag is thus allowed to be inflated by a triggering signal from the sensor 80. The active ON-state, and thus the second locking position, is preferably used when the user 3 is doing the intended activity.

In one embodiment, when the airbag system 100 is in a second mode, the control unit 50 is configured to set the airbag system 100 in an active state and as an optional step, the system may also alert the user 3 that the state of the airbag system 100 has been changed to the active state.

It is apparent to a person skilled in the art that the basic idea may be implemented in various ways. The invention and its embodiments are thus not limited to the examples described above; instead they may vary within the scope of the claims.