Abstract:
An impact detection apparatus ( 10 ), comprising: first and second electrical contacts ( 26   a   ,26   b   ; 30   a   ,30   b ); and a detector ( 22 ) configured to detect bridging of the first and second contacts. The first and second electrical contacts ( 26   a,   26   b;    30   a   ,30   b ) are separated by a distance that is bridgeable by a predefined electrically conducting implement ( 16   a   ; 16   b ), and the detector ( 22 ) is configured to detect the closing of a circuit upon any impact of the implement ( 16   a   ; 16   b ) sufficient to bridge the first and second electrical contacts ( 26   a   ,26   b   ; 30   a   ,30   b ) and to respond by outputting a signal indicative of the impact.

Description:
RELATED APPLICATION 
       [0001]    This application is based on and claims the benefit of the filing date of Australian application no. 2009905275 filed 28 Oct. 2009, the content of which as filed is incorporated herein by reference in its entirety. 
       FIELD OF THE INVENTION 
       [0002]    The present invention relates to an impact detection method and apparatus, of particular but by no means exclusive application in the detection of impacts in sports such as boxing and various martial arts. 
       BACKGROUND OF THE INVENTION 
       [0003]    Various systems have been proposed for detecting impact in sports such as boxing that employ accelerometers, piezoelectric sensors or motion sensors. 
         [0004]    For example, U.S. Pat. No. 6,925,851 discloses a method and system for detecting and displaying the impact of a blow received on an item of athletic equipment. The system includes a plurality of items of athletic equipment, such as boxing gloves, each having a force sensor, logic and a wireless transmitter therein, a receiver adapted to receiver signals from each of the transmitters, and a processor for formatting the data for display. The logic identifies and stores signals exceeding a threshold for transmission. 
         [0005]    U.S. Pat. No. 4,824,107 discloses a sports scoring device, including a piezoelectric transducer, for generating an analog output signal indicative of an impact to the transducer. The transducer may be mounted on protective equipment, such as a head guard, hand or footgear or protective vests, or can be mounted on training equipment, such as a heavy bag or striking pad. 
         [0006]    U.S. Patent Application No. 20060047447 discloses a system for monitoring an athlete&#39;s performance during an athletic event, such as a boxing match or kick-boxing match, including a plurality of monitoring articles attached to each fighter and a computing device positioned outside the fighting environment. Each of the monitoring articles preferably includes a motion sensing device, a microprocessor and a wireless transceiver. Each monitoring article creates a real-time impact force signal for each punch or kick, which is wirelessly transmitted outside of the fighting environment to the computing device for processing into an impact value for transmission to and image on an electro-optical display. 
         [0007]    U.S. Pat. No. 6,611,782 discloses a real-time boxing sports meter, wherein a power sensing unit is incorporated into a boxing glove for use according to a method of quantifying impact forces in a boxing match in real time. Impact force data is transmitted from the boxing glove to a remote receiver, and collated to assess the strike force generated by each boxer. 
         [0008]    U.S. Pat. No. 5,723,786 discloses a boxing glove accelerometer provided in a boxing glove body to measure impact. 
         [0009]    U.S. Pat. No. 5,978,972 discloses a helmet system including at least three accelerometers and mass memory for recording in real-time orthogonal acceleration data of a head. One embodiment includes at least three orthogonal accelerometers mounted within a sports helmet together with means for recording, in real-time, the data output from the accelerometers. 
         [0010]    U.S. Pat. No. 7,128,692 discloses a system for providing quantitative assessment and relaying of fighter performance, using modified ergometer based technology, optical sensor and motion analysis technology, accelerometers, and hydraulic meters for the measuring or improvement of the performance of fighters, for the facilitating of recruiting efforts, or for the enhancement of boxing matches. 
         [0011]    Other approaches are taught by U.S. Pat. Nos. 4,027,535 and 4,330,119. U.S. Pat. No. 4,027,535 discloses a manual thrust gauge comprising a frame having either a hand grip or a wrist strap, with a weighted member movably mounted to the frame and restrained by a spring which moves relative to a fixed member; one of these members comprises a scale and the other being a pointer and the movable member being releasably detained in any one of several displaced positions so that the user may thrust his hand as in a boxing punch, a karate chop or the like and the pointer will register on the scale the relative acceleration or deceleration of the punch. U.S. Pat. No. 4,330,119 discloses an inflatable striking member for being struck by the user in exercising or training, which yields a numerical, or other quantitative or qualitative indication, of factors relating to the striking factors, hopefully stimulating and encouraging the user to maximum attainments from the exercise or training. The device comprises an inflatable body member surrounding a conduit support member having a plurality of apertures therein, the apertures being in communication with the interior of the inflated member. A pressure/force responsive device is attached to the conduit such that a force applied to the inflatable member will be indicated by the pressure/force responsive device. 
         [0012]    U.S. Pat. No. 4,208,048 discloses a punching bag with a power gauge, for use in developing boxing technique to indicate punching power during work-outs with practice equipment. The bag has a punch-receiving area with a pneumatic structure with connection through a releasable check-valve to a pressure gauge oriented for visibility by the person practising. 
       SUMMARY OF THE INVENTION 
       [0013]    According to a first broad aspect, therefore, there is provided an impact detection apparatus, comprising:
       first and second electrical contacts; and   a detector (such as comprising an ammeter, a voltmeter, an ohmmeter or electronic circuitry) configured to detect bridging of said first and second contacts;   wherein said first and second electrical contacts are separated by a distance that is bridgeable by a predefined electrically conducting implement (such as a boxing glove or a police baton), and said detector is configured to detect the closing of a circuit upon any impact of said implement sufficient to bridge said first and second electrical contacts and to respond by outputting a signal indicative of said impact.       
 
         [0017]    The apparatus may comprise a garment, such as a vest, or a head guard, such as a helmet. 
         [0018]    Thus, in one embodiment a combination of electrical regions on, for example, two separate wearable items (such as textiles and garments such as vests, gloves and headguards) and appropriate electronic circuitry—such as in a wearable unit—is used to detect impacts in defined areas of two or more garments. In such an embodiment, impact is detected when an electrically conductive region on one garment connects with an electrically active region on another garment such that this impact contact leads to the completion of an electrical circuit on one or more of the garments, resulting in contact detection in the electronic circuitry. Typically the two contacting items are being worn by different people. The use of defined areas for contact and electrical connection across two separate garments has the advantage of enabling the discrimination of key scoring events in specified regions of the body, such as those used to score in amateur boxing (viz. the upper torso and head). 
         [0019]    The present invention thus permits a more objective scoring in, for example, boxing. However, it is envisaged that it may be used advantageously in other activities, including other contact sports, various non-contact sports (for monitoring illegal contacts), training activities (such as in hand-to-hand combat or in the use of police batons) and activities where projectiles strike the body (such as ‘paintball’). 
         [0020]    The apparatus may comprise a web affixable or fastenable to a garment. 
         [0021]    In one embodiment, the first and second electrical contacts comprise first and second elongate members. 
         [0022]    In a particular embodiment, the first and second electrical contacts comprise first and second wires, and may be interlaced. 
         [0023]    The apparatus may comprise a resilient region (such as an elastic region). In such an embodiment, the resilient region may include the first and second electrical contacts. 
         [0024]    The apparatus may comprise a hydrophobic region (which may comprise some or all of the apparatus). In such an embodiment, the hydrophobic region may include the first and second electrical contacts. 
         [0025]    The hydrophobic region may, for example, be created by application of a stain resistant or hydrophobic composition (such as one of the Oleophobol (trade mark) range of compositions). 
         [0026]    In a particular embodiment, the first and second electrical contacts are formed using textile processing. For example, this may be done with a circular knitting machine, such as a 28 gauge (needle per inch) 30 inch diameter 48 feed Jumberca Mini Jacquard double knit machine model 4TJ, and a mixture of non-electrically conductive and electrically conductive yarns (such as polyester and silver coated nylon yarn respectively) knitted into a two layer structure, with the electrically conductive yarns provided as alternating stripes on one side thereby providing the first and second electrical contacts. 
         [0027]    The first and second electrical contacts may be in any suitable form including but by no means limited to: foils, wires, fibres or a flexible substrate on which a metal has been applied (such as, in the last case, a substrate coated with a metal by conventional spraying, direct contact, printing, or other vapour or chemical deposition technique). 
         [0028]    In one particular embodiment, the first and second electrical contacts comprise nylon thread with a silver coating, or silver coated nylon yarn such as Shieldex (trade mark) 125/17 (2 ply). 
         [0029]    In one embodiment, the apparatus comprises an electrical power supply (comprising, for example, one or more batteries), wherein the first and second electrical contacts are electrically coupled to the power supply, the first electrical contact, the second electrical contact and the power supply constitute an open circuit, and the detector is configured to detect the closing of the circuit upon any impact of the implement sufficient to bridge said first and second electrical contacts. 
         [0030]    The power supply may comprise one or more batteries. 
         [0031]    In certain embodiments, the detector comprises an ammeter, a voltmeter or electronic circuitry. 
         [0032]    In a particular embodiment, the detector comprises an ohmmeter and the detector is configured to determine an occurrence of the impact from a drop in resistance between the first and second electrical contacts. 
         [0033]    The implement may have an electrically conductive material or coating for bridging the first and second contacts. 
         [0034]    The implement may have an electrically conductive region. 
         [0035]    In a certain embodiment, the apparatus has a first impact detection zone comprising the first and second contacts, and the apparatus includes one or more additional impact detection zones provided with further respective pairs of electrical contacts. 
         [0036]    The apparatus may further comprise one or more sensors. The one or more sensors may be selected from the group consisting of: an accelerometer, an electroencephalogram and a force sensor (such as a piezoelectric sensor). 
         [0037]    The signal output by the detector may be indicative of a force of the impact (such as by indicating a minimum value in resistance between the contacts during the impact). 
         [0038]    According to a second broad aspect, the invention provides an impact detection apparatus, comprising:
       first and second electrical contacts comprising interlaced elongate members with respective electrical connectors for electrically coupling said first and second electrical contacts to a detector;   wherein said first and second electrical contacts are separated by a distance that is bridgeable by a predefined electrically conducting implement so that said detector can detect a bridging of said first and second electrical contacts by said implement.       
 
         [0041]    The apparatus may comprise a garment, such as a vest, or a head guard, such as a helmet. 
         [0042]    The apparatus may comprise a web affixable or fastenable to a garment. 
         [0043]    In one embodiment, the first and second electrical contacts comprise first and second elongate members. 
         [0044]    In a particular embodiment, the first and second electrical contacts comprise first and second wires, and may be interlaced. 
         [0045]    The apparatus may comprise a resilient region. In such an embodiment, the resilient region may include the first and second electrical contacts. 
         [0046]    The apparatus may comprise a hydrophobic region. In such an embodiment, the hydrophobic region may include the first and second electrical contacts. 
         [0047]    In a particular embodiment, the first and second electrical contacts are formed using textile processing. 
         [0048]    According to a third broad aspect, the invention provides an impact detection system, comprising:
       an apparatus as described above;   a predefined electrically conducting implement adapted to close the circuit by bridging the first and second electrical contacts upon impact therewith; and   a communication mechanism for communicating the output signal from the detector to an impact monitor;   wherein the impact monitor is configured to record or display a record of the impact.       
 
         [0053]    The implement may have an electrically conductive material or coating for bridging the first and second contacts. 
         [0054]    The communication mechanism may be a wireless communication system, such as system utilizing the Bluetooth (trade mark) wireless protocol. 
         [0055]    It should also be understood that the various features of each of the above aspects may be combined with each other and with the other aspects and features as desired. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWING 
         [0056]    In order that the invention may be more clearly ascertained, embodiments will now be described, by way of example, with reference to the accompanying drawing, in which: 
           [0057]      FIG. 1  is a schematic view of a wearable impact detection system according to an embodiment of the present invention; 
           [0058]      FIG. 2  is a schematic circuit diagram of several principal components of system of  FIG. 1 ; 
           [0059]      FIG. 3  is a schematic view of the processing controller and user interface of the computer of the system of  FIG. 1 ; 
           [0060]      FIG. 4  is a schematic view of the memory of the computer of the system of  FIG. 1 ; 
           [0061]      FIG. 5  is a schematic view of a wearable impact detection system according to another embodiment of the present invention; 
           [0062]      FIG. 6  is a plot of impact data collected with the system of  FIG. 1  under various test conditions; and 
           [0063]      FIG. 7  is schematic view of a modified conductive region of a glove of the system of  FIG. 1 . 
       
    
    
     DETAILED DESCRIPTION 
       [0064]    A wearable impact detection system according to an embodiment of the present invention is shown generally at  10  in  FIG. 1 . System  10  is adapted for use in the sport of boxing, and includes a vest  12  and a protective head guard  14  (to be worn by a first boxer), and a pair of boxing gloves  16   a ,  16   b  (to be worn by a second boxer). System  10  also includes a personal computer in the form of a laptop computer  18 , a wireless router coupled to computer  18 , in the form of Bluetooth hub  20 , and a controller  22  that is electrically coupled to vest  12  and head guard  14 , and in wireless communication by Bluetooth protocol with Bluetooth hub  20 . 
         [0065]    It should be noted that, although system  10  includes a single vest  12 , a single head guard  14  and a single pair of boxing gloves  16   a ,  16   b , other embodiments also include a second vest and a second head guard (to be worn by the second boxer) a second pair of boxing gloves (to be worn by the first boxer), and a second controller in wireless communication by Bluetooth protocol with Bluetooth hub  20 . 
         [0066]    Vest  12  has a first impact detection zone  24  occupying most of the front of vest  12  and, in use, over the chest of the first boxer. Impact detection zone  24  comprises a separately manufactured piece of fabric into which is woven an interlaced but spaced apart pair of electrical wires  26   a ,  26   b  (termed “first and second wires  26   a ,  26   b ” below). 
         [0067]    First impact detection zone  24  is treated with a hydrophobic agent to repel moisture (from perspiration, water, etc), lest substantial shorting occur. Optionally, suitable composed hydrophilic regions may be created to draw any moisture away from electrical wires  26   a ,  26   b , and to facilitate evaporative cooling. Impact detection zone  24  comprises a separately manufactured piece of fabric so that rest of vest  12  (essentially comprising a conventional vest or shirt) can be manufactured of an electrically insulating material to act as an electrical barrier between first impact detection zone  24  and the first boxer. 
         [0068]    First and second wires  26   a ,  26   b  are electrically connected to controller  22 , as is described in greater detail below. Similarly, head guard  14  is provided with a second impact detection zone  28  (located, in use, over the forehead of the first boxer and also treated with a hydrophobic agent) provided with its own respective pair of electrical contacts in the form of interlaced, spaced part electrical wires  30   a ,  30   b  (termed “third and fourth wires  30   a ,  30   b ” below). Third and fourth wires  30   a ,  30   b  are also electrically connected to controller  22  (as described below), via a connector cable  32 . (In one variation of this embodiment, system  10  includes a second controller—comparable to controller  22 —to which third and fourth wires  30   a ,  30   b  are connected, and which communicates wirelessly with Bluetooth hub  20 ; connector cable  32  is not required.) 
         [0069]    Each of gloves  16   a ,  16   b  has a generally circular conductive region  34   a ,  34   b , respectively. Conductive regions  34   a ,  34   b  may comprise coatings or adhered conductive patches. Possible coatings include a silver coated copper screening compound (RS 247-4251) or a nickel screening compound (e.g. electrolube, NSC 4008), applied to gloves  16   a ,  16   b  using a mask to control the shape and extent of regions  34   a ,  34   b . Possible conductive patches include patches of a plain weave woven fabric formed with Shieldex silver plated nylon yarn (e.g. 125/17 2-ply), adhered to gloves  16   a ,  16   b  with—for example—a 3M (trade mark) spray adhesive, patches of aluminium foil or patches of aluminium coated polyester film, chosen according to application and desired wear characteristics. 
         [0070]    The textile components of system  10  can be formed from separate layers and these may be integral and reusable or disposable so that they can be removed from vest  12 , gloves  16   a ,  16   b  or head guard  14  and replaced as desired. This can be advantageous for items that suffer from significant wear, or where the basic item is otherwise not electrically conductive and requires a simple cheap modification (such as forming gloves  16   a ,  16   b  from conventional boxing gloves by the addition of conductive patches). 
         [0071]    The basic operating principals of system  10  are as follows. When the second boxer lands a punch on the first boxer in either first or second impact detection zone  24 ,  28 , the respective conductive region  34   a ,  34   b  bridges either first and second electrical wires  26   a ,  26   b  of vest  12  or third and fourth electrical wires  30   a ,  30   b  of head guard  14 . Controller  22  is configured to act as a detector of such a bridging, such as by detecting a change in current through one or more of electrical wires  26   a ,  26   b ,  30   a ,  30   b , a change in voltage across a respective pair of electrical wires  26   a ,  26   b  or  30   a ,  30   b , or a change in resistance (or equivalently conductivity) between a respective pair of electrical wires  26   a ,  26   b  or  30   a ,  30   b . In this embodiment, controller  22  acts as an ohmmeter, and—in response to an event—outputs an 8 bit signal indicative of the value of the resistance between, respectively, first and second electrical wires  26   a ,  26   b  and third and fourth electrical wires  30   a ,  30   b  to computer  18  via Bluetooth hub  20 . 
         [0072]      FIG. 2  is a schematic circuit diagram of several principal components of system  10  of  FIG. 1 , including first, second, third and fourth electrical wires  26   a ,  26   b ,  30   a ,  30   b  and controller  22 . Controller  22  has a pair of 2-pin connectors  36   a ,  36   b  for coupling, in use, to a complementary pair of 2-pin connectors  38   a ,  38   b  connected to, respectively, first and second electrical wires  26   a ,  26   b  and third and fourth electrical wires  30   a ,  30   b . These connectors  36   a ,  36   b ,  38   a ,  38   b  thus couple the electrical wires  26   a ,  26   b ,  30   a ,  30   b  to controller  22 . 
         [0073]    Controller  22  includes a microprocessor  40  and, between microprocessor  40  and connectors  36   a ,  36   b , respective pull-down resistors  42 , a line protection circuit  44  and respective current limiters  46 . Controller  22  also includes a power supply comprising one or more batteries (not shown, but represented in the figure as “VCC”). 
         [0074]    As described above, controller  22  acts as an ohmmeter; this functionality is provided by electronic circuitry in microprocessor  40 . Pull-down resistors  42 , in this embodiment, are used to limit the current to no more than 10 μA, principally to reduce power usage, the risk of electrical shock, and the corrosion of electrodes. The resistors are selected to match power supply VCC. Microprocessor  40  can be of essentially type of microprocessor or microcontroller with analogue input (so that signal conditioning is not required). 
         [0075]    Controller  22  also includes a wireless communication system (not shown) employing the Bluetooth protocol, though it will be appreciated that other wireless communication systems would be acceptable, according to application, required bandwidth and the number of controllers (cf. embodiments in which each of a plurality of boxers or other users has a controller). 
         [0076]    Computer  18  includes a processing controller and a user interface, shown schematically at  50  and  52  respectively in  FIG. 3 . Processing controller  50  includes a memory  54  and a digital processor  56 . Processing controller  50  is in data communication with user interface  52  (comprising a keyboard, a computer mouse and a display), and is configured to process event signals received from controller  22  according to a processing procedure (stored as processing instructions in memory  54 , as discussed below) and to output processing outcomes (which may comprise impact detection results or outputs formed by processing those results) to user interface  52 . Processor  56  processes the processing instructions and output processing outcomes to user interface  52 . The term “processor” is used to refer generically to any device that can process processing instructions and may comprise a microprocessor, microcontroller, programmable logic device or other computational device. 
         [0077]      FIG. 4  is a schematic view of memory  54 , which includes RAM  58 , EPROM  60  and a mass storage device  62 . RAM  58  typically temporarily holds program files for execution by processor  56  and related data. EPROM  60  may be a boot ROM device and/or may contain some system or processing related code. Mass storage device  62  is typically used for processing programs. 
         [0078]    Referring to  FIG. 3 , processor  56  of processing controller  50  includes a display controller  64  for controlling the display of user interface  52 , an event signal processor  66 , an event storage manager  68 , a rule retriever  70 , a rule comparator  72  and a scoring module  74 . Memory  54  of processing controller  50  includes an event storage  76  and a rule conditions storage  78  for storing rules defining various categories of impacts. Scoring module  74  determines a score from the output of rule comparator  72 . 
         [0079]    Event signal processor  66  and event storage manager  68  together provide logger functionality. Event signal processor  66  is passed event signals received from controller  22 , discriminates between signals indicative or real and spurious events (rejecting the latter), extracts data transmitted in the signal associated with real events (including the measured resistance and hence force of the impact and whether the event arose from an impact on first impact detection zone  24  or on second impact detection zone  28 ), retrieves the time of receipt of the event (from a clock of computer  18 ) and passes the retrieved data and time to event storage manager  68 . Event signal processor  66  discriminates between real and spurious events depending on the data contained in the signal. For example, a contact may be considered real (and hence a scoring event) if of suitable duration, such as between 10 and 1000 ms. 
         [0080]    Event storage manager  68  stores the data and time as a new record in event storage  76 . Rule retriever  70  is adapted to retrieve rules from rule conditions storage  78 , and rule comparator  72  is adapted to compare impacts (retrieved from event storage  76  by event storage manager  68 ) with rules retrieved from rule conditions storage  78 . 
         [0081]    In a first mode of use, every impact to first or second impact detection zone  24 ,  28  is recorded by processing controller  50  as an event associated with a measured resistance value and a time in event storage  76 . At the end of a bout, an operator controls computer  18  to stop collection; scoring module  74  determines a score based on a simple tally of the total number of events to user interface  52 . In such a mode, rule comparator  72  need not be employed. 
         [0082]    In a second mode of use, a number of points may be assigned to each impact, with more points awarded for an impact on one of first and second impact detection zones  24 ,  28 . In this mode, rule comparator  72  compares each recorded event (collected as described above) with a rule in conditions storage  78  that specifies how many points should be awarded in each case, and passes the result to scoring module  74 . Scoring module  74  then determines a score for output to user interface  52 . 
         [0083]    In other embodiments, system  10  includes one or more other sensors, such as one or more accelerometers (typically in gloves  16   a ,  16   b  or the forearm or wrist of the second boxer) to assist with impact discrimination, piezoelectric force sensors (on vest  12  or head guard  14 ), an electroencephalogram comprising heart rate monitoring electrodes (on vest  12 ). When these sensors are provided in gloves  16   a ,  16   b , it is envisaged that the second boxer (i.e. the wearer of gloves  16   a ,  16   b ) will also have a vest and a head guard comparable to vest  12  and head guard  14 , and a controller comparable to controller  22 ; sensors provided in gloves  16   a ,  16   b  will thus be coupled to that additional controller. Signals from all these sensors will be transmitted by controller  22  (or the additional controller) to Bluetooth hub  20 . 
         [0084]    The accelerometers are used in such embodiments to measure arm/wrist/fist acceleration, allowing the contact time of an impact (determined from the time for which first and second wires  26   a ,  26   b  are bridged or closed during an impact) can be used to assist in the discrimination of impact magnitude. For example, whilst the mass associated with the delivery of an impact by seconde boxer may not be easily determined, the contact time (derived from inter-garment connection) and velocity (derived from an accelerometer located on, for example, a forearm or wrist) of a punch can be combined to distinguish between hard and soft punches where relative impact impulse is proportional to velocity and time. Mathematical pattern recognition techniques can be applied to accelerometer signals to assist such categorisation. 
         [0085]    Piezoelectric force sensors may advantageously be located in non-scoring or illegal zones of the first boxer, so that punches to those zones can be detected irrespective of the contacting part of the second boxer (e.g. a punch top the back, a knee to the groin or a headbutt to any part of the body of the first boxer). 
         [0086]    Event signals generated by such additional sensors are processed and stored in by processing controller  50  in essentially the same manner as impact events detected by the bridging of first and second wires  26   a ,  26   b  or of third and fourth wires  30   a ,  30   b . If system  10  includes such additional sensors, such as in competition where the application is more demanding and system  10  required to be more discerning in rejecting spurious events, event signal processor  66  discriminates between real and spurious events additionally using data derived from these additional sensors. For example, an impact in vest  12  of the first boxer (particularly of greater than average force) should coincide with a high acceleration reading from an accelerometer provided in, for example, gloves  16   a ,  16   b . Thus, event signal processor  66  in such embodiments either rejects certain events as spurious (such as when an impact is not accompanied by a simultaneous or near simultaneous acceleration) or, if of the correct nature (e.g. an impact to vest  12  and acceleration of a glove  16   a ,  16   b ) and nearly simultaneous (to within a predefined window of, for example, 40 ms), associates and time stamps such events within a common wireless environment so as to ensure time synchronisation. 
         [0087]    In such embodiments, multiple wireless controllers may be employed; each boxer, for example, may have as many as four or more transmitters. This may give rise to band limitations or network constraints, depending on the type of wireless communication that is employed. For example, the Bluetooth protocol supports one  1  master with  7  slaves, so plural ‘piconets’ may be required. 
         [0088]      FIG. 5  is a schematic view of such an embodiment, to illustrate possible rules (as stored in rule conditions storage  78 ) for scoring.  FIG. 5  represents the first boxer (X) and the second boxer (Y), each equipped with a vest (V) and a head guard (H) comparable to vest  12  and head guard  14 , and each wearing left and right gloves (GL, GR) comparable to gloves  16   a ,  16   b  but equipped with accelerometers (A). Controller  22  includes firmware (not shown) that includes an analogue to digital converter for converting the analogue voltage detected across first and second wires  26   a ,  26   b  or third and fourth wires  30   a ,  30   b  to an eight bit digit such that, when a particular impact signal (S (XCV or XCH) ) from vest  12  or head guard  14  of first boxer X is greater than a certain value, i (e.g. i=0), and less than another value, I (e.g. I=15), and the impact duration, t c(XCV or XCH) , is within a certain range (e.g. 15 to 150 ms), then a scoring event is sent to computer  18 , which determines an updated cumulative score for second boxer Y and displays that updated cumulative score on its display. The update to the score may depend on whether the impact signal arose from an impact to vest  12  or to head guard  14 . 
         [0089]    Furthermore, the aforementioned rules can take account of digitised signals from other transducers, such as signals SYA GL,GR  from one or more accelerometers located on first and second boxers&#39; gloves, to provide further event discrimination. For example, an impact signal (S (XCV or XCH) ) from the first boxer X could be deemed to be real (and not due to noise or some other artefact) if it corresponds, to within a certain specified time tolerance, with an accelerometer signal from the glove of second boxer Y, and that accelerometer signal falls within certain limits j and J (such as j=6 g and J=60 g, also to exclude bogus signals). For example, the contact of second boxer Y&#39;s left glove might result in a signal from an accelerometer provided therein that corresponds in time with a signal detected on the first boxer X&#39;s vest  12 , which would allow computer  18  to confirm a left hit by second boxer Y to the body scoring region of first boxer X. 
         [0090]    Such a set of rules may be summarised as follows: 
         [0000]    
       
         
               
               
             
           
               
                   
               
               
                 Rule Set 
                 Score Second Boxer (Y) 
               
               
                   
               
             
             
               
                 1 
                 X CV  or X CH   
               
               
                   
                 (i &lt; S (XCV or XCH)  &lt; I) 
               
               
                   
                 (15 ms &lt; t c(XCV or XCH)  &lt; 150 ms) 
               
               
                 2 
                 (X CV  or X CH ) and (YB GL  or YB GR ) 
               
               
                   
                 (i &lt; S (ACV or ACH)  &lt; I) 
               
               
                   
                 (15 ms &lt; t c(XCV or XCH)  &lt; 150 ms) 
               
               
                   
                 (j &lt; SYA GL, GR  &lt; J) 
               
               
                   
                 t(XA CV  or XA CH ) ~ t(YA GL  or YA GR ) 
               
               
                   
               
             
          
         
       
     
         [0000]    
       
         
               
               
             
           
               
                   
               
               
                 Rule Set 
                 Score First Boxer (X) 
               
               
                   
               
             
             
               
                 1 
                 Y CV  or Y CH   
               
               
                   
                 (i &lt; S (YCV or YCH)  &lt; I) 
               
               
                   
                 (15 ms &lt; t c(YCV or YCH)  &lt; 150 ms) 
               
               
                 2 
                 (Y CV  or Y CH ) and (XA GL  or XA GR ) 
               
               
                   
                 (i &lt; S (BCV or BCH)  &lt; I) 
               
               
                   
                 (15 ms &lt; t c(YCV or YCH)  &lt; 150 ms) 
               
               
                   
                 (j &lt; SXA GL, GR  &lt; J) 
               
               
                   
                 t(B CV  or B CH ) ~ t(A GL  or A GR ) 
               
               
                   
               
             
          
         
       
     
       EXAMPLE 
       [0091]    A vest  12  was formed from knitted materials such that it was elastic, so that the size and location of first impact detection zone  24  would be maintained relative to the size of the torso of the first boxer. This was to allow a standard sized vest  12  to be worn by boxers of different torso sizes, but nonetheless provide a first impact detection zone  24  that—in each case—would generally cover the chest of the boxer from level with the arm pits to the navel. 
         [0092]    System  10 , modified to include (as described above) piezoelectric force sensors, was then tested and functioned well in test mode; events were detected on gloves, vest and head guard. The analogue circuit of controller  22  (see  FIG. 2 ) was configured such that, when first and second wires  26   a ,  26   b  were not bridged, the resistance was 100 kΩ with a nominal current of 33 μA; this state was assigned a digital value of 255, while shorting of this circuit was assigned a value of 0. A typical bridging impact from a circular conductive region  34   a ,  34   b  of gloves  16   a ,  16   b  respectively resulted in a contact value of S XCV ˜5. 
         [0093]      FIG. 6  is a plot of sensor value (where 0 corresponds to 0 Ω and 255 corresponds to 10 kΩ) versus time t(s) collected from punches to vest  12  (with glove  16   a ) worn by a plastic torso, shown at  80   a  and  80   b , and from the impact of an arm wrapped in a cloth soaked in 4% saline solution (to simulate a sweaty arm) to vest  12  worn by the plastic torso, shown at  82 . The signals  80   a ,  80   b ,  82  are significantly different in signal amplitude and duration. 
         [0094]    Tests with saline solution thrown onto vest  12  showed much of the water falling off vest  12  and more complex shaped low amplitude signals with extended duration. A test with the wet blanket underneath vest  12  failed to yield a signal. Punch impacts were typically 300 Ω for −50 ms whilst other sweat related events were &gt;1000 Ω for &gt;˜500 ms. Importantly, glove contact was found to produce a lower resistance (cf.  FIG. 6 ) than the wetting events, permitting discrimination. 
         [0095]    It appears, therefore, that it should be possible to measure the extent of perspiration of a boxer if system  10  is configured and calibrated appropriately. 
         [0096]    On this basis, rules were established to filter out events arising from contacts with wet bodies (i.e. where S XCV ˜67) and to facilitate the reliable discrimination between punch contacts and push touches; these rules comprised setting i=0, I=15 and 15 ms&lt;t c(YCV or YCH) &lt;150 ms. 
         [0097]    A glove  16   a ,  16   b  was modified to alter the area of the glove&#39;s conductive region  34   a ,  34   b ; this was observed to significantly reduce self contact arising from blocking punches with defensive poses whilst scoring contacts were maintained at a high rate (indeed, with no observable change). This was achieved by reducing the area of conductive region of the scoring area of the glove in the lower finger region such that the conductive bar was thinner than the distance between any two contacts on vest  12  or head guard  14 . 
         [0098]      FIG. 7  is a schematic view of the modified conductive region  86  (shown with conductive region  34   a  for comparison, and with exemplary portions of first and second wires  26   a ,  26   b ). Modified conductive region  86  comprises a horizontal portion  86   a  (of height Yglove1) and a vertical portion  86   b  (of width Xglove). The width Xglove of vertical portion  86   b  is less than the nominal spacing Xvest of first and second wires  26   a ,  26   b.    
         [0099]    Modifications within the scope of the invention may be readily effected by those skilled in the art. It is to be understood, therefore, that this invention is not limited to the particular embodiments described by way of example hereinabove. 
         [0100]    In the claims that follow and in the preceding description of the invention, except where the context requires otherwise owing to express language or necessary implication, the word “comprise” or variations such as “comprises” or “comprising” is used in an inclusive sense, that is, to specify the presence of the stated features but not to preclude the presence or addition of further features in various embodiments of the invention. 
         [0101]    Further, any reference herein to prior art is not intended to imply that such prior art forms or formed a part of the common general knowledge in Australia or any other country.