WO2018206804A1

WO2018206804A1 - Electronic sensing devices

Info

Publication number: WO2018206804A1
Application number: PCT/EP2018/062268
Authority: WO
Inventors: Eivind SOLBERG
Original assignee: Playfinity As
Priority date: 2017-05-12
Filing date: 2018-05-11
Publication date: 2018-11-15
Also published as: GB201707645D0

Abstract

An electronic sensing device (2) comprising a housing(4) rotationally symmetric about an axis. A sensing unit is fixed within the housing and is arranged to provide sensor data.The sensing unit comprises at least one accelerometer and/or at least one gyroscope. A wireless communication transceiver is arranged to transmit said sensor data to an external electronic device for processing. The device further comprises amounting arrangement (10, 30) adapted to connect the electronic sensing device (2) to a user-operated peripheral device such that the sensing unit is only in a predefined location and a predefined orientation about the axis relative to the user-operated peripheral device.

Description

Electronic Sensing Devices

The present invention relates to an electronic sensing device comprising a sensing unit that can be mounted to a user-operated peripheral device only in a predetermined position, in particular only in a predefined location and orientation.

With the ever-increasing number of portable electronic devices we carry about our person on a daily basis, the amount of time that is spent interacting with such devices is also steadily increasing. Furthermore, studies have shown that over recent years there has been a paradigm shift from active play (e.g. outdoor games) to more sedentary activities such as playing video games on a games console, a tablet or a smartphone.

The Applicant has appreciated that there is scope to bring some of the mechanisms that make video gaming so appealing to real-world, active play. These can be features relating to game mechanics such as automated scoring systems and monitoring infractions of the rules of the game but also extend to escapism - for example a fantasy setting game may provide users with the sense that a physical ball that they hold in their hand is a 'fireball' that they can 'launch' at opponents by throwing it at them.

In order to reduce a user's need to focus on a screen (e.g. the touchscreen of their smartphone), the Applicant provides a platform for 'sensor driven audio games', wherein the user keeps an electronic device (e.g. their smartphone) about their person, such as in their pocket or in a bag, and simply has game-related information provided to them aurally, e.g. via their headphones. Their device may also communicate with other electronic devices (e.g. other players' smartphones or electronic sensing devices used in a game) in the field-of-play in order to participate in the game. Depending on the game, one or more players may use a peripheral device (such as a toy gun, ball, base, or other throwable, mobile, or stationary object) in addition to their smartphone.

Regardless of audio outputs that may be provided when playing a game, the Applicant proposes an electronic sensing device that can generate meaningful sensor data when mounted to a user-operated peripheral device, for example during game play.

When viewed from a first aspect, the present invention provides an electronic sensing device comprising:

a housing rotationally symmetric about an axis;

a sensing unit fixed within the housing, said sensing unit comprising at least one accelerometer and/or at least one gyroscope arranged to generate sensor data;

a wireless communication transceiver arranged to transmit said sensor data to an external electronic device for processing; and a mounting arrangement adapted to connect said housing to a user-operated peripheral device such that the sensing unit fixed within the housing is mountable only in a predefined location and a predefined orientation about the axis relative to the user-operated peripheral device.

Thus it will be appreciated by those skilled in the art that the present invention provides an electronic sensing device that can be mounted to user-operated peripheral devices such as balls, flying discs, toy guns, etc. only in a predefined position, i.e. location and rotational orientation, that is known a priori such that sensor data produced by the sensing unit has a known, predetermined relationship with the orientation of the user-operated peripheral device. Those skilled in the art will appreciate that if the electronic sensing device, and more specifically the sensing unit, were permitted any orientation provided by the rotational symmetry of the housing, it could, for example, be ambiguous as to whether the user were pointing the toy gun directly in front of them, or straight up in the air. However, the mounting arrangement employed by embodiments of the present invention advantageously ensures that the positioning of the device relative to the peripheral device is known. This means that, when the sensor data is transmitted to an external electronic device (e.g. a smartphone) for processing, this external electronic device does not need to calibrate the data or perform any complex processing in order to determine the relative orientation (and, by extension the true orientations of) the sensing unit and the user-operated peripheral device. Fixing the relative orientation of the electronic sensing device and the user-operated peripheral device in this manner also advantageously prevents this relative orientation varying during use, e.g. while these devices are being used to play a game that involves a lot of movement.

By way of non-limiting example, if the user-operated peripheral device is a toy gun to be used in a shooting game (e.g. similar to laser tag) where sensor data from the accelerometer(s) and/or gyroscope(s) is used to determine where the user is aiming the toy gun, those skilled in the art will appreciate that the orientation of the electronic sensing device is of critical importance for this determination. The present invention provides a device that generates sensor data from which the external electronic device can unambiguously derive the orientation of the user-operated peripheral device (i.e. the toy gun in this example).

Once the electronic sensing device is connected to the user-operated peripheral device, a user may need to perform some initial set-up before using them, e.g. in a game. For example, the electronic device and/or the external electronic device (e.g. the user's smartphone) may need to be told when the electronic device is placed in the predefined position and orientation. In some embodiments, the electronic device comprises an interface arranged to receive a user input indicating when the electronic device is connected to a user-operated peripheral device.

Thus in accordance with such embodiments, a user manually tells the electronic sensing device that it is connected to a peripheral device. The user may also provide a similar user input to the external electronic device, however in a set of embodiments the electronic sensing device is arranged to transmit, by use of the wireless communication transceiver or otherwise, a notification to the external electronic device indicating when the electronic sensing device is connected to a user-operated peripheral device.

However, in a preferred set of embodiments, the electronic sensing device further comprises a proximity sensor arranged to determine when the electronic sensing device is connected to a peripheral device. Thus, in accordance with such embodiments, the electronic sensing device may be able to determine automatically when it is connected to the user- operated peripheral device. This automatic determination may then be communicated to the external electronic device, for example using the wireless communication transceiver.

It will be appreciated by those skilled in the art that there are a number of proximity sensors that could be readily used in order to implement such embodiments of the present invention. In a set of such embodiments, the electronic sensing device comprises a switch and the user-operated peripheral device comprises an actuator, arranged such that the actuator actuates said switch when the electronic sensing device is connected to the peripheral device. A microswitch may be used. Alternatively, the electronic device and the user-operated peripheral device could form a capacitive proximity sensor arrangement. Other proximity sensor arrangements, such as optical and acoustic proximity sensing arrangements, known in the art per se, could be used in order to provide this automatic detection of the electronic sensing device being connected to a peripheral device. However, in a preferred set of embodiments, the proximity sensor comprises a magnetic field sensor, preferably a Hall effect sensor.

Whether or not the electronic sensing device is connected to a user-operated peripheral device may then be determined from the strength of the magnetic field detected by the magnetic field sensor.

It will be appreciated that one or more types of sensor data may be generated by the sensing unit. In addition to the at least one accelerometer and/or gyroscope, the sensing unit may comprise one or more further sensors.

In some embodiments, the sensing unit further comprises a magnetometer. A magnetometer may generate additional sensor data relating to orientation that may be processed by the external electronic device. Those skilled in the art will appreciate that magnetometers are a type of sensor that can generate sensor data relating to the direction and/or the strength of a local magnetic field. As such a magnetometer will typically be sensitive to the Earth's magnetic field, this can provide information regarding the orientation of the sensing unit and, by virtue of the sensing unit being fixed within the housing which is mountable only in a predefined orientation relative to the user-operated peripheral device, the orientation of the user-operated peripheral device. ln some potentially overlapping embodiments, the sensing unit further comprises a barometer. A barometer may generate additional sensor data relating to altitude that may be processed by the external electronic device. Data relating to altitude may be used for determining, for example, a height to which the sensing unit and hence a user-operated peripheral device has been brought, such as in a throwing game or in a game that involves running up-hill.

The Applicant has appreciated that it may, in some arrangements, be advantageous to determine the absolute position of the sensing unit, for example in a real-world co-ordinate system. In some embodiments, in addition or alternatively, the sensing unit comprises a position sensor. This position sensor may, for example, comprise a global positioning system (GPS) sensor, however those skilled in the art will appreciate that there are many other positioning systems, satellite-based or otherwise, that could be used to determine the position of the sensing unit, for example other satellite-based positioning systems such as Global Navigation Satellite System (GLONASS), Galileo, and BeiDou or non-satellite-based positioning systems such as indoor positioning systems.

It will be appreciated by those skilled in the art that there are many wireless

communication standards and protocols that could be used by the wireless communication transceiver, however in at least some such embodiments, the wireless communication transceiver is arranged to transmit the sensor data (and, where appropriate any other messages such as data or notifications) using at least one protocol selected from the group comprising: Bluetooth®; Bluetooth® Smart; ZigBee®; Wi-Fi®; and WiMAX™.

The electronic sensing device is typically provided with a compartment for an internal battery or comprises a battery in order to provide the electronic components thereof with a source of electrical power. This battery may be replaceable or, additionally or alternatively, it may be rechargeable. Where the battery is replaceable, the battery may be located within a battery compartment within the housing and covered by a removable battery compartment door. In some embodiments, the mounting arrangement is located on the removable battery compartment door. This is advantageous as it means that the door can be removed and replaced with another, e.g. to change the mounting arrangement. A user could potentially swap between different mounting arrangements for the electronic sensing device.

In a potentially overlapping set of embodiments, the electronic sensing device comprises a power connector connected to the battery, wherein the power connector is arranged to be connected to an external source of power such that the battery is recharged. Those skilled in the art will appreciate that there are many types of suitable power connectors that may be readily employed for this purpose, including but not limited to: cylindrical DC, Universal Serial Bus (USB), mini-USB, micro-USB, IEEE 1394 (FireWire), Lightning®, Molex®, and Tamiya® connectors. The power connector may be a socket located on the housing or may be a plug at the end of a cable integrated into the sensing unit, wherein the power connector may be connected to a plug or socket provided externally as required. In the set of embodiments wherein the electronic sensing device comprises both a removable battery compartment door and a power connector connectable to the battery, the power connector may be located on a power connector door such that a user may swap between the battery compartment door and the power connector door (e.g. for a rechargeable battery). It will be appreciated that the power connector door may comprise a mounting arrangement in an analogous manner to the removable battery door.

In a potentially overlapping set of embodiments, the electronic sensing device comprises an inductive charging unit connected to the battery. This means that the battery can be charged wirelessly, for example by placing the electronic sensing device on an inductive charging pad.

The first aspect of the invention extends to a system comprising an electronic sensing device and a user-operated peripheral device, said electronic sensing device comprising:

a housing rotationally symmetric about an axis;

a sensing unit fixed within the housing, said sensing unit comprising at least one accelerometer and/or at least one gyroscope arranged to generate sensor data; and

a wireless communication transceiver arranged to transmit said sensor data to an external electronic device for processing;

wherein the housing comprises a mounting arrangement and the user-operated peripheral device comprises a peripheral mounting arrangement, wherein the mounting arrangement and the peripheral mounting arrangement are adapted to connect with one another such that the sensing unit fixed within the housing is mounted to the user-operated peripheral device only in a predefined location and a predefined orientation about the axis relative to the user-operated peripheral device.

In some embodiments, the mounting arrangement comprises at least one recess located on a surface of the housing. The at least one recess may be arranged to engage with one or more protrusion(s) on the user-operated peripheral device that extend(s) from a surface of the user-operated peripheral device at a location at which the electronic sensing device is to be mounted. For example, if the user-operated peripheral device is a hollow ball that may be separable into two halves, into which the electronic sensing device is to be mounted, the interior surface of one or both halves of the ball may have a protrusion such as a peg or a post extending therefrom. The recess on the housing then receives the peg or post so as to prevent the electronic sensing device rotating in-plane within the ball during use.

In arrangements where there is more than one recess and/or more than one protrusion, it is possible for the number of each of these to be different to one another. This may be advantageous where it is desirable for the electronic sensing device to be mounted at a finite number of different locations and/or orientations relative to the user-operated peripheral device, i.e. there may be multiple possible predefined configurations in which the electronic sensing device and peripheral device can validly be connected together. Of course, it will be appreciated that, depending on their placement, this may also be true where there are the same number of recesses and protrusions.

In a particular set of embodiments, there is the same number of recesses located on the housing as there are protrusions extended from the surface of the user-operated peripheral device and, in use, there is a one-to-one engagement of protrusions and recesses when the electronic sensing device is placed in the predefined position and orientation relative to the peripheral device. Extending the hollow ball example given previously, the interior surface of one or both halves of the ball may have a number of protrusions (e.g. pegs or posts), for example two, three, four, or more protrusions, extending therefrom and the housing may have the same number (i.e. two, three, four, or more as appropriate) of recesses. These may be arranged in a rotationally symmetric manner, wherein the degree of rotational symmetry sets the number of predefined orientations that the electronic sensing device can be placed in relative to the user-operated peripheral device. However, in at least some such embodiments, the plurality of recesses and the plurality of protrusions are arranged rotationally asymmetrically such that there is only one predefined orientation in which the electronic sensing device can be placed relative to the user-operated peripheral device.

It will of course be appreciated that the positioning of the recess(es) and protrusion(s) could be reversed, in that the one or more recess(es) could be located on a surface of the user- operated peripheral device and the one or more protrusions could extend from a surface of the housing. This is, however, less preferred as having protrusions extending from the housing may restrict certain motions of the electronic sensing device, for example making it difficult to slide on its top or bottom surface along a floor. Also, having protrusions extending from the housing may make the device less safe for use in certain activities, for example where it is being thrown around during a game.

Thus it will be seen that the provision of the recess provides a mechanism for mounting the electronic sensing device to a peripheral device. This may allow for mounting the electronic sensing device on a protrusion such as a peg or a post as described hereinabove. However, the Applicant has appreciated that other mounting arrangements may alternatively, or in addition, be used to connect the electronic sensing device in the predefined location and orientation relative to a peripheral device. In some embodiments, the mounting arrangement comprises at least one groove in a surface of the housing. This groove may engage with a retaining member located on a surface of the user-operated peripheral device. For example, the retaining member may take the form of an elongated protrusion such as a ridge, or a line of protrusions, that is received in the groove. In other examples, this groove may engage with a retaining member that is separate from the user-operated peripheral device but acts to connect the devices together. Such a retaining member may comprise a band (elasticated or otherwise), a string, a cord, a rope, a cable, a wire, or any other such suitable mechanism or combination thereof that may engage with the at least one groove so as to mount the electronic sensing device to the user-operated peripheral device.

In a potentially overlapping set of embodiments, the recess comprises a through-hole that passes from a first surface of the housing to a second surface of the housing. Such a through-hole may, for example, provide the ability to mount or connect the electronic sensing device to other arrangements, e.g. on the user-operated peripheral device or otherwise. For example, a user may feed a rope (e.g. a skipping rope) through the through-hole or may hang the electronic sensing device on a vertical surface such as a tree or a wall using a nail received in the through-hole. In at least some embodiments the through-hole may provide a socket to engage with a clamping arrangement, for example by receiving a plug or bolt. A clamping arrangement such as a nut and bolt, or a plug, may be used to clamp the housing to a user- operated peripheral device via the through-hole. Accordingly a system as described above may comprise a clamping arrangement that is configured to engage with the through-hole. For example, a bolt having a body portion and a wider head portion may be used such that the body portion is inserted through the through-hole and screwed into a nut provided by the user- operated peripheral device. For example, a plug may be inserted through the through-hole from the user-operated peripheral device and form an interference fit. Once the housing is clamped to the user-operated peripheral device, it may not be removed without first releasing the clamping arrangement.

Such a through-hole could be a cylindrical, frustoconical or conical hole that passes from the first to the second surface in a straight line such that the axis of the through-hole is orthogonal (i.e. normal) to both the first and second surfaces, for example parallel to the axis of the housing. However, in some embodiments, the through-hole passes from the first surface of the housing to the second surface of the housing at an oblique angle to the axis of the housing. Those skilled in the art will appreciate that, in accordance with such embodiments, the profile of the through-hole may have at least one straight line that is not parallel with the axis of the housing. Such a profile may allow the electronic sensing device to be 'fired' from a 'slingshot' type arrangement wherein a (preferably angled at the same oblique angle as the through-hole) guide member passes at least partly through the through-hole and an elasticated band may be passed around at least part of the housing. The housing may then be pulled back, stretching the elasticated band, and released so as to fire the electronic sensing device forwards (i.e. in the opposite direction to the direction in which it was pulled back). Having the through-hole pass through the device at an oblique angle to the axis of the housing may advantageously allow the electronic sensing device to move away from the guide member with relative ease. ln a set of potentially overlapping embodiments, the through-hole comprises a first opening having a first diameter at the first surface of the housing and a second opening having a second, different diameter at the second surface of the housing. In accordance with such embodiments, the through-hole may be frustoconical. The first diameter may be between 7 mm and 1 1 mm, and is preferably between 8 mm and 10 mm, and is most preferably 9 mm. The second diameter is preferably less than the first diameter and may be between 4 mm and 8 mm, and is preferably between 5 mm and 7 mm, and is most preferably 6 mm.

In some arrangements, the centres of the first and second openings may be aligned with one another along the axis of the housing. At least in accordance with some embodiments, the through-hole may pass from the first surface to the second surface, wherein the openings (e.g. circular or oval apertures) at each surface have a different diameter to one another, wherein the through-hole passes through the housing at an oblique angle to the axis of the housing, preferably such that the through-hole has an oblique frustoconical profile. In a preferred set of embodiments, the first and second openings are arranged such that a point on the

circumference of the first opening is in-line with a corresponding point on the circumference of the second opening, such that a line between the point on the circumference of the first opening and the corresponding point on the circumference of the second opening is parallel to the axis about which the housing is rotationally symmetric. Those skilled in the art will appreciate that, in accordance with such embodiments, the through-hole may have a profile having a straight line between the lined-up points on the circumferences of the openings, wherein this straight line is parallel to the axis of rotational symmetry, while the rest of the profile is tapered. This advantageously provides the ability for the electronic sensing device to be both hanged on a vertical surface and to be fired from a slingshot arrangement as described previously.

The mounting arrangement provides a mechanism to mount and dismount the electronic sensing device to a user-operated peripheral device, i.e. to ensure that the housing is only in the predefined location and orientation about the axis relative to the user-operated peripheral device. The mounting arrangement may provide a temporary connection. However, in some potentially overlapping embodiments, the mounting arrangement comprises a fastening arrangement. Those skilled in the art will appreciate that the term "fastening arrangement" as used herein is understood to be an arrangement in which the electronic sensing device may be fixedly connected to the user-operated peripheral device.

In a set of such embodiments, the fastening arrangement comprises a slot. The peripheral mounting arrangement may, at least in some embodiments, comprise an

engagement member such as a protrusion located on the user-operated peripheral device. This engagement member may then engage with the slot so as to fasten the housing to the user- operated peripheral device. The slot may have bevelled walls so as to provide the groove of a tongue-and-groove fastening arrangement. The Applicant has appreciated a number of different mechanisms by which the fastening arrangement may be fixedly connected to the peripheral mounting arrangement. In some embodiments, the fastening arrangement is arranged to engage with the engagement member by rotating the housing relative to the peripheral mounting arrangement. For example, a user may place the electronic sensing device such that the fastening arrangement is proximate to the peripheral the housing, e.g. by lining up the slot with the engagement member described above, and rotating the housing so as to lock the housing in place on the peripheral mounting arrangement. The engagement member may comprise a bayonet pin arranged to engage with the slot of the fastening arrangement. In one or more such embodiments, the slot may intersect the axis of the housing. For example, the slot may be formed in an outer surface of the housing to coincide with the axis. The sensing device may therefore be rotated about the axis to fasten the housing to the peripheral mounting arrangement e.g. in a "twist and lock" fastening.

In some potentially overlapping embodiments, the fastening arrangement is arranged to engage with the peripheral mounting arrangement by sliding the housing relative to the engagement member. For example, a user may place the electronic sensing device such that the fastening arrangement is proximate to the peripheral mounting arrangement, e.g. by lining up the slot with the engagement member described above, and sliding the housing so as to lock the housing in place on the peripheral mounting arrangement (e.g. such that the engagement member slides into the slot). In one or more such embodiments, the slot may be an elongate slot to facilitate a "slide and lock" fastening. For example, the elongate slot may extend across an outer surface of the housing. Such an elongate slot may be positioned away from the axis of the housing, as a sliding movement in any direction might be used to fasten the electronic sensing device irrespective of the rotational symmetry of the housing. However, in a sub-set of embodiments, the elongate slot may extend across an outer surface of the housing to intersect the axis. This means that the same slot may provide for fastening by both sliding and rotating the housing relative to the engagement member, e.g. depending on the shape of the

engagement member in a given peripheral mounting arrangement.

Such a tongue-and-groove fastening arrangement as described hereinabove may be sufficient to hold the electronic sensing device in place on the user-operated peripheral device. However, in at least some embodiments, the peripheral mounting arrangement comprises a flexible tongue portion having an alignment member located thereon, wherein said flexible tongue portion is moveable out-of-plane with respect to a plane of the peripheral mounting arrangement and wherein said alignment member is arranged to at least partially engage with a recess on the housing, e.g. when the sensing unit fixed within the housing is mounted to the user-operated peripheral device in the predefined location and the predefined orientation. The recess on the housing with which the alignment member engages is preferably a through-hole in accordance with embodiments described hereinabove. In accordance with such embodiments, when the user fastens the electronic sensing device to such a peripheral mounting arrangement, the housing pushes down on the flexible tongue portion (e.g. by pushing down on the alignment member) which moves out-of-plane with respect to the peripheral mounting arrangement such that the engagement member may engage with the slot.

Once the sensing unit is in the predefined location and orientation, the flexible tongue portion may then return to its resting position and the alignment member may engage (at least partially) with the recess on the housing. This alignment member assists in preventing the electronic sensing device becoming accidentally dislodged from the peripheral mounting arrangement. In a set of such embodiments, the flexible tongue portion may selectably be locked in place such that it cannot move while in a locked position. This may, by way of non- limiting example only, be advantageous in arrangements wherein the user-operated peripheral device is a throwable disc as locking the flexible tongue portion may further aid in preventing the electronic sensing unit coming away from the disc during use.

In a potentially overlapping set of embodiments, the peripheral mounting arrangement comprises a fixed portion and at least one sliding portion that is slidingly moveable relative to the fixed portion. The electronic sensing device may be positioned between the fixed and sliding portions and the sliding portion(s) moved towards the fixed portion to clamp the housing therebetween. Such a peripheral mounting arrangement may ensure that the housing is mounted only in a predefined location and orientation by at least one of the fixed portion and sliding portion(s) engaging with a recess or a groove located on a surface of the housing. The sliding portion(s) and/or the fixed portion may comprise an arm carrying a retaining member that engages with a recess or a groove located on a surface of the housing. However, if there is a compatible recess or groove at more than one orientational position on the housing then it may be preferable for the peripheral mounting arrangement to include an engagement member as described above. In at least some of those embodiments, the engagement member protrudes from the fixed portion such that the at least one sliding portion is slidingly moveable relative to the engagement member. In accordance with such embodiments, a user fastens the electronic sensing device to such a peripheral mounting arrangement by locating the slot over the engagement member and sliding and/or rotating the housing relative to the engagement member to lock the housing in position on the fixed portion. The sliding portion(s) can then be moved towards the fixed portion to clamp the housing therebetween, for example with one or more retaining members engaging in one or more recesses or grooves on the housing. This means that the electronic sensing device is both locked and clamped in position by the peripheral mounting arrangement, resulting in a very strong fastening that can withstand impacts e.g. when throwing the peripheral device. In a potentially overlapping set of embodiments, the peripheral mounting arrangement comprises a fixed portion and a pair of resiliency deformable clamping arms. The electronic sensing device may be positioned over the fixed portion between the clamping arms so that the clamping arms deform to clamp the housing therebetween. Such a peripheral mounting arrangement may ensure that the housing is mounted only in a predefined location and orientation by at least one of the clamping arms engaging with a recess or a groove located on a surface of the housing. One or both of the clamping arms may carry a retaining member that engages with a recess or a groove located on a surface of the housing. However, if there is a compatible recess or groove at more than one orientational position on the housing then it may be preferable for the peripheral mounting arrangement to include an engagement member as described above. In at least some of those embodiments, the engagement member protrudes from the fixed portion and the the clamping arms are resiliency deformable (e.g. by flexing) to accommodate the housing when the engagement member engages with the slot. In accordance with such embodiments, a user fastens the electronic sensing device to such a peripheral mounting arrangement by locating the slot over the engagement member and sliding and/or rotating the housing relative to the engagement member to lock the housing in position on the fixed portion. The clamping arms then act to clamp the housing therebetween, for example with one or more retaining members engaging in one or more recesses or grooves on the housing. This means that the electronic sensing device is both locked and clamped in position by the peripheral mounting arrangement, resulting in a very strong fastening that can withstand impacts e.g. when throwing the peripheral device.

In a potentially overlapping set of embodiments, the slot comprises a first portion having a first width and a second portion having a second width less than said first width. Preferably, the first and second widths are selected such that the first width is greater than the width of the engagement member but the second width is less than the width of the engagement member, such that the engagement member may freely enter and exit the first portion of the slot but is retained by the second portion of the slot, unless effort is made to remove it. The wider first portion can assist in guiding an engagement member, in particular an elongate engagement member, into the narrower second portion of the slot. In some embodiments, the second portion is bevelled such that the second width reduces towards an exterior surface of the slot. In some potentially overlapping embodiments, the second portion intersects the axis of the housing. The slot may therefore provide both a sliding and a rotating fastening arrangement, e.g. depending on the shape of the engagement member in a given peripheral mounting arrangement.

Typically the depths of the first and second portions are selected such that they are "matched" to the depth of the peripheral mounting arrangement (e.g. the depth of any such engagement member as described hereinabove) on the user-operated peripheral device, that is, the slot provides a tight fit for the engagement member. In a set of embodiments, the first portion has a depth substantially equal to a depth of the second portion. By matching the depths of the first and second portions to one another (at least at the interface between the first and second portions), the electronic sensing device may be fastened to the user-operated peripheral device smoothly - i.e. the engagement member may transition between the first and second portions with minimal resistance due to discontinuities in depth.

While the slot could protrude from the housing, in preferred embodiments the slot is located in a surface e.g. outer surface of the housing, for example an aperture in the surface. By having the slot form an integral part of the housing itself, the housing may retain its cylindrical profile such that the slot does not inhibit any rolling or sliding of the electronic sensing device.

It will be appreciated by those skilled in the art that the term Yotationally symmetric', as used herein with regard to the housing of the electronic device, should be understood to mean housings that have n-fold rotational symmetry, where n>1. In a preferred set of embodiments the housing is cylindrical. The Applicant has appreciated that a cylindrical housing provides the electronic sensing device with the ability to roll on a surface, e.g. a table or a floor such as on the pavement or on a playground, which may be desirable for certain applications.

Furthermore, in a set of embodiments the housing is mirror symmetric across a plane normal to the axis around which it is rotationally symmetric. A device with such a mirror symmetric housing will typically roll in a substantially straight line.

It will of course be understood that housings having other shapes falling within the scope of the invention may also provide the ability to roll to various degrees or according to different trajectories. Furthermore, the term 'cylindrical' as used herein should be understood to mean that the overall profile of the housing is substantially cylindrical. By way of non-limiting example, a housing having a cylindrical profile but provided with a groove running around the curved surface should be understood to be 'cylindrical'. Similarly, housings having other polygonal profiles with sufficient rolling characteristics are envisaged.

Where there is mentioned above a recess located on a surface of the housing, a through-hole passing between surfaces of the housing, or a groove in a surface of the housing, and in embodiments where the housing is cylindrical, one or more of these features of the mounting arrangement may be provided at a planar (e.g. top/bottom) surface of the housing and/or a curved (e.g. side) surface of the housing. For example, the groove may extend across a planar surface and optionally across one or more curved surfaces. Where there is mentioned above a fastening arrangement, e.g. comprising a slot in a surface of the housing, in

embodiments where the housing is cylindrical it is preferable that the fastening arrangement is provided at a planar surface e.g. outer surface of the housing.

It will be appreciated that the mounting arrangement and peripheral mounting

arrangement may comprise one or more features that interact so that the housing is mounted only in a predefined location and orientation. In one or more embodiments of a system as defined above, it is preferable that the peripheral mounting arrangement further comprises a cavity arranged to at least partly receive the housing of the electronic sensing device. The cavity thereby provides a predefined location for the electronic sensing device. In some embodiments the cavity may be arranged to wholly receive the housing, which means that the electronic sensing device may be positioned internal to the peripheral device and thereby protected during use.

In a potentially overlapping set of embodiments, the cavity may also be rotationally symmetric about an axis, preferably the same axis as the housing of the electronic sensing device. Further preferably the cavity may be shaped to substantially match the outer profile of the housing. In embodiments where the housing is cylindrical, the cavity may also be substantially cylindrical. However, it will be appreciated that rotation of the housing inside the cavity is prevented by one or more other features of the mounting arrangement. These features, as described above, thereby provide a predefined orientation for the electronic sensing device.

In a preferred set of embodiments, a maximum height of the housing is less than a maximum width of the housing. In other words, it is preferred that the aspect ratio (i.e. the ratio of the width to the height) of the housing is greater than one. Thus, in accordance with such embodiments, the housing may be shaped like a hockey puck. The maximum height of the housing may be greater than 8 mm, preferably greater than 10 mm and more preferably greater than 12 mm, but is preferably less than 18 mm, preferably less than 16 mm, and more preferably less than 14 mm. Thus, in some embodiments, the maximum height of the housing is between 8 mm and 19 mm, preferably between 10 mm and 17 mm, more preferably between 12 mm and 15 mm. For example, the maximum height of the housing may be between 13 mm and 14 mm, and is preferably 13.5 mm or 14 mm. The maximum width of the housing may be greater than 35 mm, preferably greater than 39 mm, and more preferably greater than 41 mm, but is preferably less than 48 mm, preferably less than 44 mm, and more preferably less than 42 mm. Thus, in some embodiments, the maximum width of the housing is between 35 mm and 48 mm, preferably between 39 mm and 44 mm, more preferably between 41 mm and 42 mm, and is preferably 41 .5 mm. The electronic sensing device is preferably 'palm-sized' so that it can fit in a user's hand.

While the cylindrical housing could be formed from a single material such that it is uniform on all sides, in some embodiments the housing comprises a first substantially planar surface at least partially covered in a first material and a second substantially planar surface at least partially covered in a second, different material. These different materials may provide different coefficients of friction when the electronic sensing device is placed on a given surface, for example a table, a playground, pavement, grass, etc. The first and second materials are preferably polymeric materials. For example, the first surface may be at least partially covered with a natural or synthetic elastomer, e.g. thermoplastic elastomer (TPE), while the second surface may be at least partially covered with a non-elastomeric plastics material. Suitable non- elastomeric plastics materials include acrylonitrile-butadiene-styrene (ABS), polycarbonate, or a mix of ABS and polycarbonate - however it will be appreciated that any combination of plastics materials may be used. Thus it will be appreciated that, at least in some embodiments, the first material has a greater viscoelasticity than the second material. The Applicant has appreciated that, by providing the housing with these different materials, the electronic sensing device may slide more freely when placed one way up when compared to the other. This may be beneficial, by way of non-limiting example only, if the electronic sensing device is to be used in a game that involves sliding it, such as a hockey-like game.

This is novel and inventive in its own right and thus, when viewed from a second aspect the present invention provides an electronic sensing device comprising:

a housing rotationally symmetric about an axis, wherein the housing comprises a first substantially planar surface at least partially covered in a first material and a second

substantially planar surface at least partially covered in a second, different material;

a sensing unit fixed within the housing arranged to provide sensor data, said sensing unit comprising at least one accelerometer and/or at least one gyroscope; and

a wireless communication transceiver arranged to transmit said sensor data to an external electronic device for processing.

This second aspect of the invention extends to a system comprising an electronic sensing device and a user-operated peripheral device, said electronic sensing device comprising:

It will be appreciated by those skilled in the art that while the first and second different materials referred to hereinabove could be completely different physical substances, they may also be made from the same substance but provided with different finishes. For example, both the first and second materials could be made from ABS, however the first surface could have a smooth, polished finish while the second surface could have a rough surface (e.g. it could be 'cross-hatched' or provided with a 'bumpy' texture), which would lead to the two sides exhibiting the desired difference in the coefficients of friction between each side and a reference surface. The user-operated peripheral device may take any suitable form. In the context of sensor- driven games, the user-operated peripheral device may comprise, by way of non-limiting example: a throwable object e.g. a ball, disc, torpedo, etc.; a role play object e.g. a gun, joystick, sword, hammer, etc.; or a striking device, e.g. a racquet, bat, club, etc..

Those skilled in the art will appreciate that the optional features described hereinabove in relation to embodiments of the first aspect of the invention apply equally, where appropriate, to the second aspect of the invention.

Certain embodiments of the present invention will now be described with reference to the accompanying drawings, in which:

Figs. 1 a-g show an electronic sensing device in accordance with an embodiment of the present invention;

Figs. 2a-e show peripheral mounting arrangements suitable for connection of the electronic sensing device of Figs. 1 a-g;

Figs. 3a-g show the electronic sensing device of Figs. 1 a-g mounted in a ball in accordance with an embodiment of the present invention;

Figs. 4a and 4b show the electronic sensing device of Figs. 1 a-g mounted on a disc;

Figs. 5a and 5b show the electronic sensing device of Figs. 1 a-g mounted in a toy gun;

Fig. 6 is a block diagram of the electronic components within the electronic sensing device of Figs. 1 a-g;

Fig. 7 shows a game system including the electronic sensing device of Figs. 1 a-g and the toy gun of Figs. 5a and 5b in use;

Figs. 8a-d show an electronic sensing device in accordance with a further embodiment of the present invention;

Figs. 9a-d show a further peripheral mounting arrangement suitable for connection of the electronic sensing device of Figs. 8a-d; and

Figs. 10a-e show the electronic sensing device of Figs. 8a-d mounted in a ball in accordance with an embodiment of the present invention.

Figs. 1 a-e show an electronic sensing device 2 in accordance with an embodiment of the present invention. Each of Figs. 1 a-e show a different view of the electronic sensing device 2 and will be described in turn below.

Fig. 1 a shows a top-down view of an electronic sensing device 2. The electronic sensing device 2 comprises a cylindrical housing 4, in which the electronics of a sensing unit are housed. The various electronic components of the sensing unit within the cylindrical housing 4 are described in further detail with reference to Fig. 6 below. As is seen most clearly in Fig. 1 b, the cylindrical housing 4 is rotationally symmetric about an axis A. Fig. 1 a shows the top surface 6 of the cylindrical housing 4. As can be seen from the Figure, this front surface 6 is provided with a circular recess 8, a circular through-hole 10, and a groove 12 that runs in a straight line across the front surface 6 of the housing 4. A further recess 14 extends part way down the curved side surface 16 of the cylindrical housing 4 as can be seen more clearly in Fig. 1 c. The groove 12 extends down the entire length of the curved surface 16, i.e. the height of the housing 4, as can be seen in Fig. 1 b. The through-hole 10 extends from the front surface 6 to a back surface 18 of the cylindrical housing 4 as can be seen in Figs. 1 d and 1 e. By way of contrast, the circular recess 8 extends only part way into the interior of the cylindrical housing 4 and does not extend to the bottom surface 18.

Fig. 1 b shows a perspective view of the electronic sensing device 2. As can be seen from Fig. 1 b, the height of the housing 4, i.e. the height 20 of the curved surface 16, is less than the width of the housing 4, i.e. the diameter 22 of the circular front surface 6. In other words, the aspect ratio (i.e. the ratio of the width to the height) of the cylindrical housing 4 is greater than one. This provides the electronic sensing device 2 with an overall "hockey puck" profile.

Fig. 1 c shows a side-on view of the electronic sensing device 2. As can be seen in

Fig. 1 c, the curved side surface 16 of the housing 4 is provided with a push button 24. This push button 24 may, for example, be used to power on the electronic sensing device 2 and/or may be used to select a function of the electronic sensing device 2 and/or may be used for other functions as required. It will be appreciated that the push button 24 could be located at any suitable location on the housing 4. For example, the side recess 14 could house the push button 24 (or a further push button) rather than being used as an alignment feature.

Fig. 1 d shows a top-down view of the bottom surface 18 of the housing 4, i.e. the underside of the electronic sensing device 2. As can be seen in Fig. 1 d, the bottom surface 18 of the housing 4 includes a battery door 26 which provides access to the battery (not shown) of the electronic sensing device 2 for ease of replacement. This battery door 26 is fastened to the rest of the cylindrical housing 4 by rotating it into place (e.g. in the direction indicated by the arrow 58) and by using a screw 28 to affix the battery door 26 to the rest of the housing 4. The bottom surface 18 of the housing 4 is also provided with a slot 30 which, in this case, is located on the battery door 26. The slot 30 provides a fastening arrangement for the electronic sensing device 2.

As can be seen in Figs. 1 d and 1 e, which provides a perspective view of the underside of the electronic sensing device 2, this slot 30 is recessed from the bottom surface 18 of the housing 4 by a certain depth 32 and has a first portion with a first width 34 and a second portion with a second, smaller width 36. While the side wall 38 of the first portion of the slot 30 is substantially straight, the side wall 40 in the second, narrower portion of the slot 30 is bevelled. This bevel provides the slot 30 with a width that increases with depth in the second portion. The front surface 6 and the bottom surface 18 of the housing 4 may be (at least partially) covered in different materials. The surfaces 6, 18 may also be covered in the same material but provided with different surface finishes. For example, the top surface 6 may be wholly or partly covered with a thermoplastic elastomer (TPE) while the bottom surface 18 may be wholly or partly covered with acrylonitrile-butadiene-styrene (ABS). Due to the different materials on these surfaces 6, 18, the electronic sensing device 2 may slide more freely when placed one way up when compared to the other, depending on the material properties of the surface on which the electronic sensing device 2 is placed and the coefficient of friction between this surface (e.g. tarmac or concrete) and the top surface and bottom surfaces 6, 18.

The circular recess 8, through-hole 10, groove 12, side recess 14, and slot 30 each provide part of a mounting arrangement for the electronic sensing device 2. Each of these are described in turn below. Although the illustrated embodiments provide a mounting arrangement comprising multiple parts, it will be appreciated that one or more of these parts may be sufficient to ensure that the housing 4 is mountable only in a predefined location and orientation, as will be described further below.

The circular recess 8 that extends part way into the electronic sensing device 2 from the front surface 6 of the electronic sensing device 2 provides one mechanism for mounting or fastening each electronic sensing device to a peripheral device. If a peripheral device is provided with a protrusion such as a peg or a post at the correct location, this peg or post may be aligned with the recess 8 such that they engage one another, thus helping to fix the location and orientation of the electronic sensing device 2 relative to the peripheral device.

The through-hole 10 may in addition, or alternatively, be used to engage with a protrusion such as a peg or a post on a peripheral device. However, due to the fact that the through-hole 10 extends the whole way through the electronic sensing device 2, i.e. from the front surface 6 to the back surface 18, the through-hole 10 may provide additional or alternative means for fastening the electronic sensing device 2 to a peripheral device. For example, a closed loop may be fastened around the housing 4 by passing the loop through the through- hole 10. This may be used for connecting the electronic sensing device 2 to a carabiner. The through-hole 10 may also be used to pass a rope (e.g. a skipping rope or jump rope) through the electronic sensing device 2 or may be used to hang the electronic sensing device 2 on a vertical surface such as a wall or a tree using a nail or a hanger. The through-hole 10 may also be used to clamp or fasten the electronic sensing device 2 to a surface without damaging the housing 4, e.g. by using a bolt having a body portion that fits within the through-hole 10 and a head portion wider than the through-hole 10, or a plug sized to form an interference fit with the through-hole 10. The geometry of this through-hole 10 is described in further detail below with reference to Fig. 1 g. The groove 12 provides an additional or alternative part for connecting the housing 4 to a peripheral device or to a user's body (e.g. to an arm or a hand) or on to stationary elements such as trees, benches, poles, etc. For example, if the peripheral device is provided with a complementary mounting part such as an elastic band, such an elastic band may be aligned with the groove 12 so as to hold the electronic sensing device 2 in place at a particular location and in a particular orientation. The groove 12 may also be used to align the housing 4 with an elongated protrusion or a line of protrusions on the peripheral device so as to prevent the housing 4 from rotating relative to the peripheral device. The groove 12 may also be used to connect the housing 4 to a peripheral device through engagement with a retaining bracket provided on the peripheral device such as a clip or a clasp.

The side recess 14, similarly to the circular recess 8 described previously, may be arranged to engage with a protrusion provided on the peripheral device. This side recess 14 may also be used in conjunction with one or more of the other parts described above to remove any ambiguity as to the correct orientation of the housing 4, where needed. For example, if the groove 12 were to run exactly across the diameter of the housing 4 and designed to engage with a complementary mounting part on the peripheral device, the housing 4 would have twofold rotational symmetry such that there would be two possible orientations of the housing 4 about its axis A relative to the peripheral device. The provision of the side recess 14 may eliminate one of the two possibilities such that only a single orientation of the housing 4 about its axis A relative to the peripheral device is possible.

The slot 30 may be used to fasten the housing 4 to a mounting bracket on the peripheral device such as those described below with reference to Figs. 2a-e. While the circular recess 8, through-hole 10, groove 12, and side recess 14 may be used to mount the electronic sensing device 2 to a peripheral device in such a way that it is relatively easy to connect and disconnect the electronic sensing device 2 to and from the peripheral device, the slot 30 may provide a semi-permanent, fixed connection (i.e. a fastening arrangement) between the housing 4 and the peripheral device. The slot 30 may provide a linear e.g. sliding or rotational fastening of the electronic sensing device 2 to the peripheral device depending on the type of mounting bracket provided on the peripheral device as described below.

It will, however, be appreciated that the battery door 26 is optional. Fig. 1f shows an alternative embodiment of an electronic sensing device 2' formed as a sealed unit such that the battery is not replaceable and where a slot 30' is integrated into the bottom surface 18' of the housing 4'. As described previously, a through-hole 10' passes from a top surface (not shown) of the housing 4' to the bottom surface 18'. A power socket 1 1 is also provided on the bottom surface 18' of the housing 4' (or elsewhere) and provides a means to supply electrical power to recharge the internal battery. This power socket 1 1 may be arranged to receive a power plug of a type known in the art, for example: cylindrical DC, Universal Serial Bus (USB), mini-USB, micro-USB, IEEE 1394 (FireWire), Lightning®, Molex®, and Tamiya® connectors. The power connector could of course instead be a plug at the end of a cable integrated into the electronic sensing device 2' arranged to connect to an external socket - for example the electronic sensing device 2' could have an integrated USB cable with plug suitable for connection to a USB socket on a computer or a mains to USB adaptor.

Fig. 1 g shows a cross-sectional view of a through-hole 10 as described previously. As can be seen from Fig. 1 g, the through-hole 10 has a first opening 7 located on the top surface 6 of the housing 4 and a second opening 9 located on the bottom surface 18 of the housing 4. Both of these openings 7, 9 are circular apertures, however they are of different diameters; the diameter 13 of the top opening 7 is greater than the diameter 15 of the bottom opening 9, leading to the through-hole 10 having a tapered, frustoconical profile. By way of example only, the diameter 13 of the top opening 7 may be 9 mm while the diameter 15 of the bottom opening 9 may be 6 mm. Of course, in other examples the openings 7, 9 may be non-circular e.g. oval apertures.

It can also be seen in Fig. 1 g that the centres of the openings 7, 9 are not aligned with each other along an axis A' but the openings 7, 9 are instead aligned at a point on their respective circumferences such that the profile of the through-hole 10 has a straight line 17 parallel with the axis A'. The axis A runs in parallel to the axis A about which the housing 4 is rotationally symmetric. The through-hole 10 is increasingly slanted moving around the circumference, away from this straight line 17, with its most slanted line 19 being diametrically opposite the straight line 17. This leads to the axis B of the through-hole 10 (i.e. the line that passes through the centres of the openings 7, 9 and that would pass through the apex of the frustocone were it to taper to a single point) being at an oblique angle Θ to the axis A. While the straight line 17 provides a "flat edge" that allows the electronic sensing device 2 to be hanged on a vertical surface such as a wall or a tree using a nail or a hanger as described previously, the tapered profile may, for example, allow the housing 4 to come away from a small guiding member such as an angled plastic peg used to retain the housing 4 as it is drawn back in a slingshot mechanism used to 'fire' the electronic sensing device 2 away from a user.

This tapered profile may of course be applied to the through-hole 10' of the electronic sensing device 2' shown in Fig. 1f.

Fig. 2a shows a mounting bracket 42 suitable for connection to the electronic sensing devices 2, 2' described previously with reference to Figs. 1 a-g. The mounting bracket 42 provides part of a peripheral mounting arrangement for a peripheral device. In this example, the mounting bracket 42 is formed from a base plate 44 having a number of screw holes 46 suitable for mounting the bracket 42 to a peripheral device such as a throwable disc or a toy gun. Of course the bracket 42 may be affixed to a peripheral device by any suitable means other than screw fasteners, for example adhesive or may be integral to the peripheral device itself. The mounting bracket 42 comprises a flexible strip 48 provided with a circular protrusion 50 at one end, and a rigid portion 52 provided with an engagement member 54. The engagement member 54 is a rigid protrusion that extends from the rigid portion 52. The engagement member 54 is provided with bevelled edges 56 as can be seen in the close up view of Fig. 2b. These bevelled edges 56 are arranged to engage with the bevelled edges 40 of the second portion of the slot 30 described previously with reference to Figs. 1 d and 1 e. The mounting bracket 42 provides part of a peripheral mounting arrangement for a peripheral device.

In order to fasten the electronic sensing device 2, 2' to a peripheral device, a user may locate the housing 4, 4' proximate to the flexible portion 48 of the mounting bracket 42 before sliding it towards the rigid portion 52. As the user does this, the flexible portion 48 flexes downwards as the underside 18, 18' of the electronic sensing device 2, 2' pushes down on the circular protrusion 50. The engagement member 54 then slides into the slot 30, first via the wider first portion 34 and subsequently into the narrower second portion 36. The user may then rotate the electronic sensing device 2 so as to lock the housing 4, 4' in place. As the electronic sensing device 2, 2' is rotated, the flexible portion 48 returns to its resting position and the circular protrusion 50 engages with the through-hole 10, 10' which helps to hold the electronic sensing device 2, 2' in place by preventing the housing 4, 4' from being rotated unless the flexible portion 48 is pushed down again. Once the electronic sensing device 2, 2' is mounted to the bracket 42, the position and orientation of the housing 4, 4' relative to the peripheral device onto which the mounting bracket 42 is connected are known.

Figs. 2c and 2d show an alternative peripheral mounting arrangement 60 for mounting the electronic sensing device 2, 2' to a peripheral device. Unlike the mounting arrangement i.e. bracket 42 described above with reference to Figs. 2a and 2b, the mounting arrangement 60 uses a linear e.g. sliding locking mechanism instead of a rotational locking mechanism. Here, the engagement member 62 is an elongated protrusion, wherein the protrusion 62 is longer in the direction in which the electronic sensing device 2, 2' slides onto the mounting arrangement 60 than in the transverse direction. This protrusion 62 is also provided with tapered sides 64 that are arranged to engage with the bevelled sides 40 in the second portion of the slot 30. In order to mount electronic sensing device 2, 2' to this mounting arrangement 60, the user places the electronic sensing device 2, 2' on the flexible portion 48 of the mounting arrangement 60 and slides the housing 4, 4' towards the rigid portion 52. As before, this pushes down on the flexible portion 48 and the housing 4, 4' slides into place such that the engagement member 62 slides into the slot 30. The engagement member 62 slides into the slot 30 first via the wider first portion 34 and subsequently into the narrower second portion 36, which means that the elongated protrusion 62 is guided into the narrower second portion 36 without requiring a user to provide exact alignment for the sliding engagement. The elongated protrusion of the engagement member 62 fully engages with the narrower second portion 36 of the slot 30 on the underside 18, 18' of the housing 4, 4' such that, due to the pair of bevelled edges 40, 64, the electronic sensing device 2, 2' cannot simply be lifted off of the mounting arrangement 60 without sliding it backwards off of the mounting arrangement 60. Furthermore, when the flexible portion 48 returns to its resting position, the circular protrusion 50 engages with the through- hole 10, 10' and prevents the housing 4, 4' sliding backwards off of the mounting arrangement 60 unless the flexible portion 48 is pushed down again. When the electronic sensing device 2, 2' is locked in place on this mounting arrangement 60, the location and orientation of the housing 4, 4' relative to the peripheral device on which the mounting arrangement 60 is provided are known.

Fig. 2e shows a further alternative peripheral mounting arrangement 61 for mounting the electronic sensing device 2, 2' to a peripheral device. Like the peripheral mounting

arrangement 60 described previously with reference to Figs. 2c and 2d, this peripheral mounting arrangement 61 provides a linear sliding mechanism for fastening the housing 4 to a user- operated peripheral device.

However, unlike the peripheral mounting arrangement 60 described previously, the circular protrusion 50 is replaced by a rigid member 55 that is flexibly mounted so as to move when pushed down by the electronic sensing device 2 as it is pushed onto the peripheral mounting arrangement 61. The peripheral mounting arrangement 61 also comprises a rigid, elongated member 53 arranged to engage with the slot 30, 30' on the bottom surface 18, 18' of the housing 4, 4' to form a tongue-and-groove fastener as described previously with reference to Figs. 2c and 2d. Once the electronic sensing device 2, 2' is in the predefined location and orientation relative to the peripheral device, the rigid member 55 returns to its resting position and engages with the wider portion of the slot 30, 30' and prevents the electronic sensing device 2, 2' from sliding back off of the rigid, elongated member 53 unless the rigid member 55 is pushed down again.

Figs. 3a-g show the electronic sensing device 2, 2' of Figs. 1 a-g mounted in a ball 66 in accordance with an embodiment of the present invention. The main body of the ball 66 is provided with a cavity 68 into which a device carrier 70 may be placed. As can be seen in Fig. 3a, the device carrier 70 slots into the cavity 68 such that the electronic sensing device 2, 2' is wholly contained within the ball 66. The device carrier 70 comprises a mounting bracket 72 having a flexible upper arm 76 which has a protrusion 74a that extends downwards from the underside of the flexible arm 76 and a protrusion 74b that extends upward from the top side of the mounting bracket 72, as can be seen in the side view of Fig. 3c and the perspective view of Fig. 3d. The upper protrusion 74a engages with the circular recess 8 on the upper side 6 of the electronic sensing device 2, 2' while the lower protrusion 74b engages with the through-hole 10, 10'. The mounting bracket 72 provides a rigid support on which the electronic sensing device 2, 2' rests while the flexible arm 76 can flex to assist with engagement of the protrusions 74a, 74b. When the electronic sensing device 2, 2' is clamped by the mounting bracket 72, the device carrier 70 may be slotted into the cavity 68 so as to form a complete ball 66. An elastomeric band 78 as shown in Fig. 3c may be used to hold the parts of the ball 66 together during use by locating the band 78 in a groove 80 that is formed on both the body of the ball 66 and the device carrier 70. With this band 78 in place, as shown in Fig. 3d, the ball 66 may safely be thrown around, e.g. during a game, without fear of the device carrier 70 becoming dislodged from the ball 66.

Figs. 4a and 4b show how the electronic sensing device 2, 2' of Figs. 1 a-g can be mounted on a disc 82 in accordance with an embodiment of the invention. The disc 82 is a throwing disc such as a Frisbee® that may be used in a throwing game. However, unlike typical throwing discs, the disc 82 is provided with a cavity 84 into which the electronic sensing device 2, 2' may be mounted. Inside the cavity 84 is located a circular mounting bracket 86

incorporating the rotational peripheral mounting arrangement 42 described previously with reference to Figs. 2a and 2b. This mounting bracket 86 is provided with an engagement member 88 which may engage with the slot 30 provided on the underside 18, 18' of the electronic sensing device 2, 2'. Once the user has placed the electronic sensing device 2, 2' into the cavity 84 and rotated it such that it locks in place as shown in Fig. 4b, the disc 82 may be thrown without the electronic sensing device 2, 2' coming away from the body of the disc 82. A locking mechanism on the underside of the disc 82 may be used to prevent the flexible portion 48 of the peripheral mounting arrangement 42 from moving while the disc 82 is being thrown around.

Figs. 5a and 5b show how the electronic sensing device 2, 2' of Figs. 1 a-g can be mounted in a toy gun 90 in accordance with an embodiment of the present invention. The toy gun 90 is similar in shape to that of a real gun, and has a grip 92, a barrel 94, a muzzle 96, a sight 98, and a trigger 100. The toy gun 90 is also provided with a cavity 102, in this example located on a side of the barrel 94. Inside this cavity 102 is located a mounting bracket 104 which is similar to the arrangement 60 described previously with reference to Figs. 2c and 2d, i.e. the toy gun 90 is provided with a linear locking mechanism for fastening the electronic sensing device 2, 2' to the toy gun 90.

In order to connect the electronic sensing device 2, 2' to the toy gun 90, the user may place the electronic sensing device 2, 2' into the cavity 102 such that it pushes down on the flexible portion 106 of the mounting bracket 104. The user may then slide the electronic sensing device 2, 2' onto the elongated engagement member 108 which, as described previously with reference to Figs. 2c and 2d, engages with the slot 30 on the underside 18, 18' of the housing 4, 4' so as to retain it. The circular protrusion 1 10 located on the flexible member 106 of the mounting bracket 104 helps to keep the electronic sensing device 2, 2' in position as shown in Fig. 5b. The electronic sensing device 2, 2' is then fastened to the toy gun 90 until the user presses an eject button 101 which pushes down on the flexible portion 106 of the mounting bracket 104, allowing the housing 4, 4' to slide off of the elongated engagement member 108 and be removed from the cavity 102.

It will be appreciated that the toy gun 90 could instead use the peripheral mounting arrangement 61 described previously with reference to Fig. 2e, and the eject button 101 could be moved to the other side of the cavity 102 if necessary.

As the position and orientation of the housing 4, 4' of the electronic sensing device 2, 2' relative to the toy gun 90 are known, due to the fact there is only one predefined position and orientation in which the electronic sensing device 2, 2' may be mounted, sensor data generated by the electronic sensing device 2, 2', e.g. data from an accelerometer and/or a gyroscope inside the electronic sensing device 2, 2', directly relates to the real-world state of the toy gun 90 in a known and predictable way. For example, if the electronic sensing device 2, 2' contains a three-axis accelerometer, and the toy gun 90 is held out at arm's length (i.e. parallel to the ground) by a user, the data from the x- and y-axis accelerometers may read zero (i.e. there is no acceleration in these directions) but the z-axis accelerometer may provide a reading of 9.81 ms^"2 due to gravity. Furthermore, if a gyroscope contained within the electronic sensing device 2, 2' provides data indicating that the housing 4, 4' is being rotated about the z-axis, it can be inferred (e.g. by an app running on a smartphone to which the electronic sensing device 2, 2' is connected and receiving data from) that a user holding the toy gun 90 has rotated either the toy gun 90 or their body while holding the toy gun 90.

During use, e.g. during a game where players 'shoot' each other (akin to laser tag), the data generated by the electronic sensing device 2, 2' is indicative of where the toy gun 90 is being aimed. If, for example, the user wishes to 'shoot' a fellow player during the game, they may aim the toy gun 90 at the target in much the same way that someone would point a real gun (e.g. by looking down the sight 98) and pull the trigger 100. The electronic sensing device 2, 2' may detect the pressing of the trigger 100 (e.g. due to a wired or wireless connection between the electronic sensing device 2, 2' and the toy gun 90 or through mechanical means) and determine where the muzzle 96 of the toy gun 90 was pointed when the trigger 100 was pulled. The processing required to make this determination may be partly made by the electronic sensing device 2, 2' itself but is typically carried out on an external electronic device (e.g. the user's smartphone or an external server). Information regarding the shot may then be communicated via the user's smartphone to the smartphone's other users including the target's smartphone either directly (e.g. in a personal area network facilitated, for example, by

Bluetooth®) or indirectly via an external server (e.g. over the Internet). Information may then be provided aurally to the user via headphones connected to their smartphone. Fig. 6 is a block diagram of the electronic components within the electronic sensing device 2, 2' of Figs. 1 a-g. The electronic sensing device 2, 2' comprises: a microcontroller 208; a three-axis accelerometer 210; a three-axis gyroscope 212; a magnetometer 214; a barometer 216; a user interface 218; memory 220; and a wireless communication transceiver 222. The microcontroller 208 is connected to the various sensors (i.e. the accelerometer 210, the gyroscope 212, the magnetometer 214, and the barometer 216) via a sensor bus 224. The sensors 210, 212, 214, 216 communicate data corresponding to their respective measurements via this bus 224 and the microcontroller 208 may perform some processing on this data, store it in memory 210 via a memory bus 226, and/or relay it to the wireless communication transceiver 222 via a communications bus 228.

The optional user interface 218 provides a mechanism for a user to interact with the electronic sensing device 2, 2', e.g. to power on the electronic sensing device 2, 2', to power off the electronic sensing device 2, 2', or to make selections such as to enter the electronic sensing device 2, 2' into a particular mode of operation. These inputs are communicated to the microcontroller 208 via an input bus 230. The microcontroller 208 may provide information to the user via this bus 230 and the user interface 218, e.g. it may display a particular pattern or colour of lights on a light-emitting diode (LED) display or panel (not shown). Such an LED display of colour may, for example, be located in the groove 12 that runs across the front surface 6 of the housing 4, 4'.

The wireless communication transceiver 222 is arranged to communicate with external electronic devices (e.g. a user's smartphone) using an antenna 232. This wireless

communication carried out by the wireless communication transceiver 222 may be carried out using, for example, Bluetooth®, Bluetooth Smart®, ZigBee®, Wi-Fi®, WiMAX™, or any other suitable wireless communication protocol. The user may be able to control the functionality of the electronic sensing device 2, 2' via an app running on their smartphone. For example, the user may indicate to the electronic sensing device 2, 2' that it has been placed in the predefined position and orientation on a peripheral device by pressing a button on a graphical user interface (GUI) which is relayed wirelessly to the electronic sensing device 2, 2', e.g. using one of the protocols listed previously. The user may be able to configure other settings for the electronic sensing device 2, 2' in this manner, such as enabling or disabling one or more of the sensors 210, 212, 214, 216 or by varying the sensitivity of one or more of these.

However, while the electronic sensing device 2, 2' may be informed of when it is connected to a peripheral device, the electronic sensing device 2, 2' further comprises a Hall effect sensor 234 that is connected to the microcontroller 208 via a proximity bus 236. This Hall effect sensor 234 may be used to detect a magnet (not shown) located on the peripheral device in a certain way such that the electronic sensing device 2, 2' may determine automatically that it has been placed in the correct position and orientation relative to the peripheral device. The electronic sensing device 2, 2' also comprises a GPS sensor 238 arranged to determine the location of the electronic sensing device 2, 2', i.e. its real-world, geographic position. The GPS sensor 238 may provide GPS data to the microcontroller 208 via a GPS bus 240, where the microcontroller 208 may then perform some processing on the GPS data or send it to an external device via the wireless communication transceiver 222. The provision of GPS data may be useful in certain applications, for example where the electronic sensing device 2, 2' is fixed to a throwing disc such as the one described previously with reference to Figs. 4a and 4b, such that the landing point of the disc may be found easily or so that its trajectory after being thrown may be seen.

Fig. 7 shows a game system including the electronic sensing device 2, 2' of Figs. 1 a-g and the toy gun 90 of Figs. 5a and 5b in use. Here, a user 138 is holding the toy gun 90 described previously with reference to Figs. 5a and 5b, into which the electronic sensing device 2, 2' has been connected using the linear mounting bracket 104. The user 148 is also carrying their smartphone 140 which is placed in their pocket 142. The user 138 is also wearing headphones 144 which are connected to the smartphone 140 in a manner known in the art per se. It will be appreciated that the smartphone 140 could be swapped for a standalone portable electronic device designed for use in gameplay.

The electronic sensing device 2, 2' and the smartphone 140 are arranged to

communicate with one another via a wireless communications link 146 between them, where the wireless communication link 146 may be carried out using a wireless protocol such as a Bluetooth® as described previously. As the user plays the game, sensor data generated by the electronic sensing device 2, 2' is relayed to the smartphone 140 via the wireless communication link 146, i.e. using the wireless communication transceiver 222 within the electronic sensing device 2, 2' as described previously with reference to Fig. 6.

When the user 138 'fires' the toy gun 90 (i.e. by pulling the trigger 100), the smartphone 140 may provide an audible signal to the user 138 via the headphones 144, e.g. simulating the sound of a gun being fired, for example by playing a sound recording of a firearm being discharged or of a 'laser weapon' being fired. The smartphone 140 may provide other information regarding the game to the user 138 via the headphones 144, for example informing them that they have been 'shot' by another player or that they have taken the lead in terms of points scored within the game.

As descried previously, the smartphone 140 may provide the smartphones of other users with information regarding the sensor data from the electronic sensing device 2, 2' either directly (e.g. via Bluetooth®) or indirectly (e.g. via a server using the Internet). Figs. 8a-d show an electronic sensing device 302 in accordance with a further embodiment of the present invention. Each of Figs. 8a-d show a different view of the electronic sensing device 302 and will be described in turn below.

Fig. 8a shows a top-down view of an electronic sensing device 302. The electronic sensing device 302 is similar in construction to the electronic sensing device 2 described previously with reference to Figs. 1 a-g. The electronic sensing device 302 comprises a cylindrical housing 304, in which the electronics of a sensing unit are housed.

Fig. 8a shows the top surface 306 of the cylindrical housing 304. As can be seen from the Figure, this front surface 306 is provided with a circular through-hole 310, similar to that of the electronic sensing device 2 of Figs. 1 a-g. However, in contrast to the electronic sensing device 2 of Figs. 1 a-g, this electronic sensing device 302 is provided with two discontinuous grooves 312a, 312b, i.e. the groove does not extend across the entire front surface 306 of the housing 304.

These side-grooves 312a, 312b extend down the entire length of the curved surface 316 as can be seen in Figs. 8b-d. The through-hole 310 extends from the front surface 306 to the back surface 318 of the cylindrical housing 304 as can be seen in Figs. 8a-c. These side- grooves 312a, 312b can be used for mounting the electronic sensing device 302 to a peripheral device as described below.

There is seen in Fig. 8c a slot 330 on the back surface 318 of the electronic sensing device 302. This slot 330 is the same as the slot 30 that provides a fastening arrangement for the electronic sensing device 2, as seen in Figs. 1 d-f and described above.

Figs. 9a-d show a peripheral mounting arrangement suitable for connection of the electronic sensing device of Figs. 8a-d.

Fig. 9a shows a clamping peripheral mounting arrangement 400, which is constructed from an outer fixed portion 402 and an inner slidable portion 404, where these outer and inner portions 402, 404 are arranged such that these portions 402, 404 can slide relative to one another. The outer fixed portion 402 comprises a base plate 406 and an upright arm 408 having an inwardly extending retaining member 410 extending from the interior surface of the upright arm 408. Similarly, the inner slidable portion 404 comprises a base plate 412 and an upright arm 414 having an inwardly extending retaining member 416 extending from the interior surface of the upright arm 414.

The sliding movement between the outer portion 402 and inner portion 404 is provided by two parallel protrusions 418 provided on the two interior surfaces of the outer portion 402 which engage with a pair of parallel recesses 420 located on the two exterior surfaces of the inner portion 404. These protrusions 418 and recesses 420 extend in the direction along which the outer portion 402 and inner portion 404 may slide relative to one another. A further base plate 422, located between the outer portion 402 and the inner portion 404, carries an engagement member 424. The base plates 406, 412 may each be able to slide relative to the further base plate 422. Optionally, one or both of the base plates 406, 412 may be spring-mounted to return to a default clamping position. This engagement member 424 is a rigid protrusion that extends from the base plate 422 and is of a similar construction to the engagement members described previously, e.g. the engagement member 54 described with reference to Figs. 2a and 2b. The engagement member 424 is provided with bevelled edges 426. These bevelled edges 426 are arranged to engage with the bevelled edges of the narrower portion of the slot 330 on the back surface 318 of the electronic sensing device 302.

As can be seen in Fig. 9b, the electronic sensing device 302 described previously with reference to Figs. 8a-d may be mounted within the clamping peripheral mounting arrangement 400. By sliding the outer portion 402 and inner portion 404 apart from one another, there is a sufficient gap to position the electronic sensing device 302 between the two parallel arms 408, 414. The electronic sensing device 302 is positioned such that the slot 330 (see Figs. 8a-d) is above the engagement member 424, and aligned such that the major axis of the slot 330 runs parallel to the major axis of the slide mounting arrangement 400. The electronic sensing device 302 is then lowered into position such that the engagement member 424 is positioned within the slot 330, as shown in Fig. 9c. The electronic sensing device 302 may be slid in a direction between the two parallel arms 408, 414 until the engagement member 424 is positioned within the narrower portion of the slot 330.

Once the electronic sensing device 302 is in position on top of the engagement member 424, the electronic sensing device 302 can be rotated in the direction of the arrow 428 (seen in Fig. 9c) in order to lock the electronic sensing device 302 in place as shown in Fig. 9d. This rotational locking mechanism functions in the same way as the rotational peripheral mounting arrangement 42 described previously with reference to Figs. 2a and 2b. During rotation of the electronic sensing device 302, the engagement member 424 becomes locked in the narrower portion of the slot 330. Once locked in position, the inner portion 404 and the outer portion 402 may be slid towards one another, such that the retaining members 410, 416 engage with the side grooves 312a, 312b of the electronic sensing device 302. Optionally, one or both of the arms 408, 414 may be resiliency deformable such that they flex to accommodate the electronic sensing device 302 and then automatically return to a default clamping position with the retaining members 410, 416 engaged with the side grooves 312a, 312b. This clamping provides a further mechanism for retaining the electronic sensing device in place, in the correct orientation, with less chance of the electronic sensing device becoming unfastened even in the event of a severe impact. It will of course be appreciated that the clamping peripheral mounting arrangement 400 could also be used with the electronic sensing device 2 described previously with reference to Figs. 1 a-g, providing the groove 12 is suitably sized for engaging with the retaining members 410, 416.

Figs. 10a-e show the electronic sensing device 302 of Figs. 8a-d mounted in a ball 500 in accordance with an embodiment of the present invention. Similarly to the ball 66 described with reference to Figs. 3a-g, the main body of the ball 500 is provided with a cavity 502 into which a device carrier 504 may be placed. The device carrier 504 slots into the cavity 502 such that the electronic sensing device 302 is wholly contained within the ball 500.

The device carrier 504 comprises a mounting bracket 506 having an engagement member 508 extending upwardly from the mounting bracket 506. The mounting bracket 506 provides a rigid support on which the electronic sensing device 302 rests when attached to the device carrier 504. As can be seen in Fig. 10c, the engagement member 508 is provided with a bevelled edge 510 which engages with the slot 330 on the rear surface 318 of the electronic sensing device 330.

The electronic sensing device 302 may slide onto the engagement member 508 in the direction shown by the arrow 512 in Fig. 10c. The engagement member 508 is an elongated protrusion, wherein the protrusion 508 is longer in the direction 512 in which the electronic sensing device 302 slides onto the device carrier 504 than in the transverse direction. In order to mount electronic sensing device 302 to the device carrier 504, the user places the electronic sensing device 302 on the mounting bracket 506 and slides its housing in the direction of the arrow 512, which allows the engagement member 508 to slide into the slot 330. The engagement member 508 fully engages with the slot 330 on the underside 318 of the housing 304 such that the electronic sensing device 302 cannot simply be lifted off of the device carrier 504 without sliding it backwards off of the engagement member 508. When the electronic sensing device 302 is locked in place on the device carrier 504, the location and orientation of the housing 304 relative to the ball 500, in which the device carrier 504 is subsequently placed as shown in Figs. 10d and 10e, are known.

Thus it will be appreciated by those skilled in the art that embodiments of the present invention provides an electronic sensing device that can be mounted to peripheral devices such as balls, flying discs, toy guns, etc. with a known, predefined position and orientation such that sensor data generated by the electronic sensing device has a known, predetermined relationship with the orientation of the peripheral device. It will be appreciated by those skilled in the art that the embodiments described above are merely exemplary and are not limiting on the scope of the invention.

Claims

1 . A system comprising an electronic sensing device and a user-operated peripheral device, said electronic sensing device comprising:

a housing rotationally symmetric about an axis;

wherein the housing comprises a mounting arrangement and the user-operated peripheral device comprises a peripheral mounting arrangement, wherein the mounting arrangement and the peripheral mounting arrangement are adapted to connect with one another such that the sensing unit fixed within the housing is mounted to the user-operated peripheral device only in a predefined location and a predefined orientation about the axis relative to the user-operated peripheral device;

wherein the mounting arrangement comprises a fastening arrangement, said fastening arrangement comprising a slot; and

wherein the peripheral mounting arrangement comprises an engagement member located on the user-operated peripheral device to engage with the slot so as to fasten the housing to the user-operated peripheral device.

2. The system as claimed in claim 1 , wherein the fastening arrangement is arranged to engage with the engagement member by rotating the housing relative to the peripheral mounting arrangement.

3. The system as claimed in claim 1 or 2, wherein the fastening arrangement is arranged to engage with the peripheral mounting arrangement by sliding the housing relative to the engagement member.

4. The system as claimed in any preceding claim, wherein the slot has bevelled walls.

5. The system as claimed in any preceding claim, wherein the slot comprises a first portion having a first width and a second portion having a second width less than said first width.

6. The system as claimed in claim 5, wherein the first and second widths are selected such that the first width is greater than the width of the engagement member but the second width is less than the width of the engagement member.

7. The system as claimed in claim 5 or 6, wherein the second portion is bevelled such that the second width reduces towards an exterior surface of the slot.

8. The system as claimed in any of claims 5-7, wherein the first portion has a depth substantially equal to a depth of the second portion.

9. The system as claimed in any preceding claim, wherein the peripheral mounting arrangement comprises a flexible tongue portion having an alignment member located thereon, wherein said flexible tongue portion is moveable out-of-plane with respect to a plane of the peripheral mounting arrangement and wherein said alignment member is arranged to at least partially engage with a recess on the housing.

10. The system as claimed in claim 9, wherein the flexible tongue portion may selectably be locked in place such that it cannot move while in a locked position.

1 1 . The system as claimed in any preceding claim, wherein the slot is located on a first surface of the housing.

12. The system as claimed in any preceding claim, wherein the housing is cylindrical.

13. The system as claimed in any preceding claim, wherein the housing is mirror symmetric across a plane normal to the axis around which it is rotationally symmetric.

14. The system as claimed in any preceding claim, wherein a maximum height of the housing is less than a maximum width of the housing.

15. The system as claimed in claim 14, wherein the maximum height of the housing is between 8 mm and 19 mm, preferably between 10 mm and 17 mm, more preferably between

12 mm and 15 mm, and more preferably between 13 mm and 14 mm.

16. The system as claimed in claim 15, wherein the maximum height of the housing is 14 mm.

17. The system as claimed in any of claims 14 to 16, wherein the maximum width of the housing is between 35 mm and 48 mm, preferably between 39 mm and 44 mm, and more preferably between 41 mm and 42 mm.

18. The system as claimed in claim 17, wherein the maximum width of the housing is 41 .5 mm.

19. The system as claimed in any preceding claim, wherein the electronic sensing device comprises an interface arranged to receive a user input indicating when the electronic sensing device is connected to the user-operated peripheral device.

20. The system as claimed in claim any of claims 1 to 19, wherein the electronic sensing device comprises a proximity sensor arranged to determine when the electronic sensing device is connected to the peripheral device.

21 . The system as claimed in claim 20, wherein the proximity sensor comprises a magnetic field sensor.

22. The system as claimed in claim 21 , wherein the proximity sensor comprises a Hall effect sensor.

23. The system as claimed in any preceding claim, wherein the sensing unit further comprises a magnetometer.

24. The system as claimed in any preceding claim, wherein the sensing unit comprises a barometer.

25. The system as claimed in any preceding claim, wherein the sensing unit comprises a position sensor.

26. The system as claimed in claim 25, wherein the position sensor comprises a global positioning system (GPS) sensor

27. The system as claimed in any preceding claim, wherein the wireless communication transceiver is arranged to transmit the sensor data using at least one protocol selected from the group comprising: Bluetooth®; Bluetooth® Smart; ZigBee®; Wi-Fi®; and WiMAX™.

28. The system as claimed in any preceding claim, wherein the mounting arrangement comprises at least one recess located on a surface of the housing.

29. The system as claimed in claim 28, wherein the at least one recess is arranged to engage with one or more protrusion(s) on the user-operated peripheral device that extend(s) from a surface of the user-operated peripheral device at a location at which the electronic sensing device is to be mounted.

30. The system as claimed in claim 29, wherein there are the same number of recesses located on the housing as there are protrusions extended from the surface of the user-operated peripheral device and, in use, there is a one-to-one engagement of protrusions and recesses when the electronic sensing device is placed in the predefined location and orientation relative to the peripheral device.

31 . The system as claimed in claim 29 or 30, wherein the plurality of recesses and the plurality of protrusions are arranged rotationally asymmetrically such that there is only one predefined orientation in which the electronic sensing device can be placed relative to the user- operated peripheral device.

32. The system as claimed in any of claims 28 to 31 , wherein the recess comprises a through-hole that passes from a first surface of the housing to a second surface of the housing.

33. The system as claimed in claim 32, wherein the through-hole passes from the first surface of the housing to the second surface of the housing at an oblique angle to the axis about which the housing is rotationally symmetric.

34. The system as claimed in claim 32 or 33, wherein the through-hole comprises a first opening having a first diameter at the first surface of the housing and a second opening having a second, different diameter at the second surface of the housing.

35. The system as claimed in claim 34, wherein the second diameter is less than the first diameter.

36. The system as claimed in claim 34 or 35, wherein the first diameter is between 7 mm and 1 1 mm, and is preferably between 8 mm and 10 mm.

37. The system as claimed in claim 36, wherein the first diameter is 9 mm.

38. The system as claimed in any of claims 34 to 37, wherein the second diameter is between 4 mm and 8 mm, and is preferably between 5 mm and 7 mm.

39. The system as claimed in claim 38, wherein the first diameter is 6 mm.

40. The system as claimed in any of claims 34 to 39, wherein the first and second openings are arranged such that a point on the circumference of the first opening is in-line with a corresponding point on the circumference of the second opening, such that a line between the point on the circumference of the first opening and the corresponding point on the

circumference of the second opening is parallel to the axis about which the housing is rotationally symmetric.

41 . The system as claimed in any preceding claim, wherein the mounting arrangement comprises at least one groove.

42. The system as claimed in any preceding claim, wherein the housing comprises a first substantially planar surface at least partially covered in a first material and a second

substantially planar surface at least partially covered in a second, different material.

43. The system as claimed in claim 42, wherein the first surface is at least partially covered with a natural or synthetic elastomer.

44. The system as claimed in claim 43, wherein the first surface is at least partially covered with a thermoplastic elastomer.

45. The system as claimed in any of claims 42 to 44, wherein the second surface is at least partially covered with a non-elastomeric plastics material.

46. The system as claimed in claim 45, wherein the second surface is at least partially covered with acrylonitrile-butadiene-styrene.

47. The system as claimed in any of claims 42 to 46, wherein the first material has a greater viscoelasticity than the second material.

48. The system as claimed in any preceding claim, wherein the slot intersects the axis of the housing.

49. The system as claimed in any preceding claim, wherein the peripheral mounting arrangement comprises a fixed portion and at least one sliding portion that is slidingly moveable relative to the fixed portion.

50. The system as claimed in claim 49, wherein the engagement member protrudes from the fixed portion such that the sliding portion is slidingly moveable relative to the engagement member.

51 . The system as claimed in any preceding claim, wherein the peripheral mounting arrangement comprises a fixed portion and a pair of resiliency deformable clamping arms.

52. The system as claimed in claim 51 , wherein the engagement member protrudes from the fixed portion and the clamping arms are resiliently deformable to accommodate the housing when the engagement member engages with the slot.