Monitoring system for vibrating apparatus

Abstract

A monitoring system for a vibrating apparatus comprises locating devices for fixing to a respective location on the apparatus. Sensor units 20 are fitted to the locating devices 40 in use. Each locati

Description

This invention relates to monitoring systems for vibrating apparatus, especially vibratory screening apparatus. BACKGROUND TO THE INVENTION It is desirable to monitor the vibrations of a vibrating apparatus such as a vibratory screening apparatus in order to monitor the operational performance of the apparatus and / or the structural condition of the apparatus. To this end it is known to provide monitoring systems that comprise vibration sensors for mounting on the apparatus. Typically, the vibration sensors are attached to the apparatus using magnets when it is desired to monitor vibrations. It is found that the location and orientation of the sensors when mounted on the apparatus is important if accurate measurement and analysis are to be achieved. However, because vibration sensors are usually mounted on the apparatus manually by a user, the location and / or orientation of the sensors may be incorrect, non-optimal and / or inconsistent, and may for example vary from screen to screen or user to user. When vibrations, acceleration and / or other performance data are measured from unsuitable locations, the result can be misleading or unenlightening. When measurements are taken from inconsistent locations, or sensor locations are mixed-up, it is difficult to accurately assess the performance / condition of the apparatus and / or to compare performance / condition across similar models. It would be desirable to mitigate the problems outlined above. SUMMARY OF THE INVENTION From a first aspect the invention provides a monitoring system for a vibrating apparatus, the system comprising: a plurality of locating devices for fixing to a respective location on said apparatus; a plurality of sensor units for releasably fitting to said locating devices, each sensor unit comprising at least one vibration sensor, wherein each locating device and a corresponding one of said sensor units have a respective mating configuration for enabling the corresponding sensor unit to be fitted to the respective locating device, and wherein the respective mating configuration of each locating device and the corresponding one of said sensor units is different from the respective mating configuration of the, or each, other locating device and corresponding one of said sensor units. Preferably, the respective mating configuration comprises a mating formation provided on the locating device and a corresponding mating formation provided on the corresponding sensor unit, wherein the corresponding mating formations optionally comprise corresponding male and female mating formations, and wherein the male mating formation may be provided on either one of the locating device or senor unit, the female mating formation being provided on the other of the locating device or sensor unit. Preferably, the location of the mating formation on the locating device and the location of the corresponding mating configuration on the sensor unit are different for each locating device and corresponding sensor unit, and wherein the corresponding mating formations for each locating device and corresponding sensor unit may otherwise be the same as each other, and / or wherein the respective mating formations of each locating device and corresponding sensor unit are otherwise different from the respective mating formations of the, or each, other locating device and corresponding sensor unit, optionally by their respective shape and / or size. Preferably, each locating device is configurable such that the mating formation has any one of a plurality of mating formation configurations so that said locating device is compatible with any one of said mating configurations. Said plurality of mating formation configurations preferably comprises a plurality of different locations on said locating device, each locating device being configurable such that the mating formation is located at any one of said locations. Each locating device optionally includes a plurality of sacrificial formations and is configurable to adopt any one of said mating formation configurations by removal or destruction of a respective one of said sacrificial formations, said sacrificial formations preferably being provided at a respective different location on the locating device. Each locating device optionally includes a plurality of female formations configured to receive a male mating formation, said female formations preferably being provided at a respective different location on the locating device. Preferably, each sensor unit is configurable such that the mating formation has any one of a plurality of mating formation configurations so that said sensor unit is compatible with any one of said mating configurations. Said plurality of mating formation configurations preferably comprises a plurality of different locations on said sensor unit, each sensor unit being configurable such that the mating formation is located at any one of said locations. In some embodiments, each sensor unit includes a plurality of sacrificial formations and is configurable to adopt any one of said mating formation configurations by removal or destruction of a respective one of said sacrificial formations, said sacrificial formations preferably being provided at a respective different location on the sensor unit. In preferred embodiments, each locating device includes a plurality of female formations configured to receive a male mating formation, said female formations preferably being provided at a respective different location on the sensor unit. Optionally, the respective mating formation of each locating device comprises an aperture, or other female formation, provided at a respective different location in the respective locating device, the 3 respective corresponding mating formation of each sensor unit comprising a locating pin, or other male formation, provided at a respective different location that matches the location of the aperture, or other female formation, on the corresponding locating device to allow each sensor unit to be fitted to the respective locator device. Optionally, the respective mating formation of each locating device comprises a respective different corner, or other differently located part, of the mouth of a seating aperture for receiving the respective sensor unit, the respective corresponding mating formation of each locating device comprising a respective different corner, or other corresponding differently located part, of a portion of said sensor unit that is received by said seating aperture when the sensor unit is fitted to the respective locator device. Preferably, the respective mating configuration is configured to enable the corresponding sensor unit to be fitted to the respective locating device but not to the, or each, other locating device, at least when the sensor unit is in a desired orientation. Preferably, each locating device comprises a body including one or more seating formation configured to receive one or more part of the respective sensor unit when the senor unit is fitted to the locating device, the or each seating formation preferably comprising an aperture, cut-out portion or recess formed in the body. The, or each, seating formation may extend through the body so that said one or more part of the sensor unit passes through the body when the sensor unit is fitted to the locating device. Said one or more part of the sensor unit that passes through the body optionally comprises attachment means for attaching the sensor unit to the apparatus, said attachment means preferably comprising one or more magnet. Preferably, the, or each, seating formation is configured to fit with the respective part of the sensor unit such that movement of the sensor unit with respect to the locating device is restricted, the or each seating formation preferably being configured to engage with, or otherwise to provide a close fit with the respective part of the sensor unit. Optionally, each locating device has a single seating formation, in the preferred form of an aperture, formed in the body, the single seating formation being shaped and dimensioned to receive a rear portion of the respective sensor unit, typically a rear portion of a housing of the sensor unit. Optionally, each locating device has a plurality of seating formations, in the preferred form of apertures, formed in the body, seating formation being shaped and dimensioned to receive a respective part of the sensor unit, in particular a respective rear portion of the sensor unit. A plurality of attachment magnets may be provided on the rear portion of the sensor unit, each seating formation being configured to receive a respective magnet. In preferred embodiments, each sensor unit and corresponding locating device include orientation means for ensuring that the sensor unit is fitted to the locating device in a desired orientation, wherein the orientation means optionally comprises a respective corresponding orientation formation provided on the sensor unit and on the locating device that fit together only when the sensor unit is fitted to the locating device in the desired orientation. Preferably, the orientation means comprises a corresponding arrangement, preferably a non-symmetrical arrangement, of the, or each, seating formation and of said one or more part of the sensor unit, such that the, or each, seating formation and said one or more part of the sensor unit only fit together when the sensor unit is fitted to the locating device in the correct orientation. Typically, each locating device is provided with a respective different arrangement, preferably a different spatial arrangement, of fixings or fixing apertures by which the locating device may be fixed to the apparatus. Preferably, each locating device includes a protective guard for shielding the sensor unit when fitted to the locating device, the guard preferably comprising a flange or other structure that projects outwardly from a body of the locating device, and wherein, preferably, the guard extends along a top of the body, or is otherwise located such that projects over the sensor unit when fitted to the locating device. From another aspect, the invention provides a screening apparatus or other vibrating apparatus adapted to include a monitoring system of the first aspect, the screening apparatus or other vibrating apparatus comprising said plurality of locating devices fixed to a respective location on said screening apparatus for removably receiving the respective sensor unit. In preferred embodiments, a respective location on the apparatus to be monitored is defined for each sensor unit of the monitoring system. In preferred embodiments the system comprises four sensor units and four corresponding sensor unit locations are defined. The preferred system is configured to ensure that each sensor unit, when mounted on the apparatus to be monitored, is in a desired location and / or orientation with respect to the apparatus and / or with respect to each other sensor unit of the system. This arrangement facilitates determination of directional aspect(s) of the movement of the apparatus, e.g. the direction of one or more axis of vibration with respect to a reference direction (which may be defined with respect to the apparatus being monitored). The preferred system is configured to ensure that each sensor unit is located at the respective desired location on the apparatus. Preferably, each sensor unit, in particular the housing or body of the sensor unit, is adapted, or adaptable, to make the sensor unit location specific, in particular to be suitable for mounting on the apparatus only at its respective desired location, and in particular for 5 coupling or fitting only to a respective locating device. The housing or body of each sensor unit may comprise a plurality of sacrificial or removable (e.g. perforated or frangible) formations (e.g. tabs) for this purpose. For example, a respective removable formation may be provided at each corner of the housing / body of each sensor unit. The sensor units of the system may have a respective different one of its formations removed in order to make each sensor unit location specific. Advantageously, the system includes a respective locating device for each sensor unit, wherein the respective locating device and sensor unit are each configured so that each sensor unit can only be coupled or fitted to the respective locating device. Advantageously, this may be achieved by providing each sensor unit and its respective locating device with corresponding mating formations, e.g. one or more set of corresponding male and female mating formations, that allow each sensor unit to be coupled or fitted only to its respective locating device, i.e. not to any of the other locating device(s) included in the system. Preferably, each locating device is configured to ensure that the respective sensor unit, when coupled or fitted to the locating device, is in a desired orientation with respect to the locating device. This may be achieved by configuring the locating device and the sensor unit so that the sensor unit can only be coupled or fitted to the locating device in one orientation. Advantageously, each locating device includes a protective guard for shielding the sensor unit, in particular for shielding the sensor unit from above. Advantageously, each locating device is configured to prevent slippage of the sensor unit with respect to the apparatus, particularly in cases where the sensor unit is attached to the apparatus using magnets. Further advantageous aspects of the invention will be apparent to those ordinarily skilled in the art upon review of the following description of specific embodiments and with reference to the accompanying description. BRIEF DESCRIPTION OF THE DRAWINGS Embodiments of the invention are now described by way of example and with reference to the accompanying drawings in which the same or similar numerals are used to denote like parts and in which: Figure 1 is a perspective view of a screening apparatus on which a monitoring system embodying the invention is installed; Figure 1A is a detail view of a sensor unit and locating device mounted on the screening apparatus of Figure 1, the sensor unit and locating device being part of the monitoring system; Figure 2 is an alternative perspective view of the screening apparatus of Figure 1; Figure 3A is a front perspective view of a first embodiment of the sensor unit; Figure 3B is a front view of the sensor unit of Figure 3A; Figure 4 is an exploded view of the sensor unit of Figure 3A and also shows the corresponding locating device; Figure 5 is a rear perspective view of a second embodiment of the sensor unit; Figure 6 is a front perspective view of the corresponding locating device for the sensor unit of Figure 5; Figure 7 is a side view of the sensor unit of Figure 5 and the locating device of Figure 6 shown spaced apart from each other; Figure 8 is a side view of the sensor unit of Figure 5 fitted to the locating device of Figure 6, i.e. in an assembled state; Figure 8A is a detail view of the assembly of Figure 8 showing interconnection of respective mating formations; Figure 9A is a perspective front view of a locating device for use with the second embodiment of the sensor unit, the locating device having a first mating configuration; Figure 9B is a front view of the locating device of Figure 9A; Figure 10A is a perspective front view of a locating device for use with the second embodiment of the sensor unit, the locating device having a second mating configuration; Figure 10B is a front view of the locating device of Figure 10A; Figure 11A is a perspective front view of a locating device for use with the second embodiment of the sensor unit, the locating device having a third mating configuration; Figure 11B is a front view of the locating device of Figure 11 A; Figure 12A is a perspective front view of a locating device for use with the second embodiment of the sensor unit, the locating device having a fourth mating configuration; Figure 12B is a front view of the locating device of Figure 21 A; Figure 13 is an exploded perspective view of the sensor unit of Figure 5 and the locating device of Figure 6; and Figure 14 is an exploded perspective view of the sensor unit of Figure 5, the locating device of Figure 6 and the respective location of the screening apparatus at which they are to be located. DETAILED DESCRIPTION OF THE DRAWINGS Referring now to Figures 1 and 2 of the drawings there is shown, generally indicated as 10, a screening apparatus suitable for use with embodiments of the present invention. Figure 1 shows the apparatus 10 from one side, while Figure 2 shows the apparatus 10 from the other side. The screening apparatus 10 may be of any conventional type or configuration, i.e. the invention is not limited to use with the particular type or configuration of screening apparatus shown in Figure 1. Typically, the screening apparatus 10 comprises one or more screening deck 11 A, 11B, each deck 11 A, 11B comprising screening media (e.g. screening mesh or screening bars) for screening material such as aggregate material (not shown). Screening typically involves separation of particulate material according to particle size. Screening apparatus such as the apparatus of Figures 1 and 2 are commonly referred to as screen boxes. The screening apparatus 10 has an inlet 12 at one end and an outlet 14 at the other end. In use, material to be screened is deposited onto the top screening deck 11A via the inlet 12 whereupon relatively small particles pass through the top screening deck 11A onto the lower screening deck 11B while larger particles remain on the top deck 11 A. The particles that remain on the top deck 11A travel along the top deck 11A and exit the apparatus 10 via the outlet 14, may be deposited onto a conveyor (not shown) or a chute (not shown) or otherwise collected by any suitable means. Of the particles that fall onto the lower deck 11B, relatively small particles pass through the lower deck 11B while larger particles remain on the top deck 11 A. The particles that remain on the lower deck 11B travel along the lower deck 11B and exit the apparatus 10 via the outlet 14, may be deposited onto a conveyor (not shown) or a chute (not shown) or otherwise collected by any suitable means. The particles that pass through the lower deck 11B may be deposited onto a conveyor (not shown) or a chute (not shown) or otherwise collected by any suitable means. In order to facilitate screening, the apparatus 10 includes a drive system 16 for causing the screening apparatus 10 to vibrate. When vibrating, the screening apparatus 10 moves in a reciprocating or oscillatory manner, which may be linear or orbital (e.g. circular or elliptical). Typically, the drive system 16 causes the screening apparatus 10 to vibrate with respect to a base (not shown), usually comprising a frame and / or a chassis. The screening apparatus 10 may be mounted on or coupled to the base in any suitable manner that supports the vibratory movement, e.g. by one or more springs (not shown). The drive system 16 may take any conventional form, typically comprising one or more motor (not shown) configured to drive, or rotate, one or more eccentric mass(es) or out-of-balance wheel(s). The drive system 16 may be referred to as a vibratory drive system. The screening apparatus 10 may be referred to as a vibratory screening apparatus. The drive system 16 may be adjustable to adjust one or more characteristics of the vibrations of the 8 screening apparatus 10. In use, the vibration of the screening apparatus 10 facilitates the separation of material by the screening decks 11A, 11B and the travelling of material along the screening decks 11 A, 11B. Typically, the drive system 16 is located at or near the centre of gravity of the screening apparatus 10 system. This arrangement tends to generate vibrations of uniform amplitude and acceleration throughout the screening apparatus. In the illustrated embodiment, the drive system 16 is located between the inlet 12 and outlet 14, preferably midway or substantially midway between the inlet 12 and outlet 14. Other locations of the drive system 16 may alternatively be adopted to suit different types of screening apparatus and applications. One option is to offset the drive system to impart vibrations with higher amplitude and acceleration to the feed end 12 of the screening apparatus 10 where material load is at a maximum. Other approaches include locating the drive above / below the screening apparatus, or providing multiple drives at different locations on the screening apparatus, and / or using crank driven leaf spring(s) or resonance drives to effect the desired motion profile. During use, the vibratory movement of the screening apparatus 10 has characteristics, in particular amplitude, acceleration and direction(s), any one or more of which it may be desired to monitor. The direction(s) of vibration may be measured with respect to any suitable reference axis or axes (e.g. a horizontal axis and / or a vertical axis, and / or one or more axis of the apparatus itself, e.g. longitudinal, transverse or vertical axis). The, or each, direction of the vibrations are sometimes referred to as the screen angle, in particular the dynamic screen angle. The vibrations may be linear, e.g. rectilinear or reciprocating, in which case the vibrations may be along a single axis, or may be circular or elliptical in which case the vibrations may be along multiple axis. It may also be desired to measure the static screen angle, i.e. the angle of apparatus with respect to one or more reference axis when the apparatus is not vibrating. It is noted that the invention is not limited to use with screening apparatus and may alternatively be used with other apparatus that vibrate in use, and which may generally be referred to as vibrating apparatus or vibratory apparatus. Such apparatus may vibrate because they include or are coupled to a vibratory drive system (such as the drive system 16), and / or because they are coupled to another vibrating or vibratory apparatus (such as the screening apparatus 10) that vibrates in use and so imparts vibrations to the apparatus being monitored. Examples of other vibrating apparatus with which embodiments of the invention may be used include feeding apparatus, walkways, conveyors, hoppers, crushers, underpans for crushers and other material processing apparatus and accessories. The vibratory movement of the screening apparatus 10 (or of any other vibrating apparatus) may be monitored by a monitoring system embodying the present invention. The monitoring system, which in preferred embodiments may be referred to as a vibration monitoring system or a condition monitoring system, comprises a plurality of sensor units 20 for mounting on the screening apparatus 10. The sensor units 20 are preferably removably mountable on the apparatus 10. Any conventional 9 removable attachment means may be used for this purpose, but in preferred embodiments each sensor unit 20 is provided with one or more magnet 24 for removably mounting the sensor unit 20 on the apparatus 10 (which is typically at least partly formed from steel or other magnetic-compatible metal). The monitoring system may comprise a single sensor unit 20, but preferably comprises at least two sensor units 20. Each sensor unit 20 is mounted, in use, at a respective location on the apparatus 10. Preferably, each sensor unit 20 is spaced apart from the, or each, other sensor unit 20 along at least one of the main orthogonal axes of the apparatus 10 (i.e. the longitudinal axis that runs in a direction from the inlet 12 to the outlet 14 in this example, the transverse axis that runs perpendicular to the longitudinal axis in a side-to-side direction, and the vertical axis). In preferred embodiments, each sensor unit 20 is spaced apart from the, or each, other sensor unit 20 along at least one of the longitudinal and transverse axes. Each sensor unit 20 is preferably spaced apart from the geometric centre or centre of mass of the apparatus 10 since the effects of the vibrations tend to increase with distance from the geometric centre or centre of mass. It is preferred to locate each sensor unit 20 on the main body 13 of the apparatus 10 rather than, for example, on a peripheral component such as a feeder, conveyor or chute since peripheral components may be affected by the vibrations in a manner that is not representative of the vibration of the apparatus 10 itself. In preferred embodiments, the monitoring system comprises four sensor units 20A, 20B, 20C, 20D, although in alternative embodiments, the monitoring system may comprise more than four or fewer than four sensor units. In use, the sensor units 20A-20D are spaced apart around the apparatus 10, preferably in a symmetric manner, e.g. with respect to the longitudinal and / or transverse axes of the apparatus 10. Preferably, sensor units 20A and 20B are located on one side of the apparatus 10 and sensor units 20B and 20 are located on the other side. Sensor units 20A and 20C are preferably located at or adjacent the inlet 12, or feed end, and sensor units 20B and 20D are preferably located at or adjacent the outlet 14, or discharge end. The sensor units 20A-20D may be located at the same or substantially the same vertical level. Typically, the main body 13 of the apparatus 10 is box-like in shape (in particular a generally square or rectangular box) and each sensor unit 20 is located at or adjacent a respective corner of the body 13. More generally, the sensor units 20 are, in use, spaced apart with respect to each other on the apparatus 10. The sensor units 20 may be spaced apart from any one or more of the geometrical centre, centre of gravity and / or vibrational centre of the apparatus. The sensor units 20 are preferably symmetrically arranged with respect to one or more of the main axes of the apparatus 10. The monitoring system may comprise a controller 22 configured to receive data indicative of or otherwise relating to the measurements taken by each sensor unit 20 during use. The sensor units 20 may be capable of communicating with the controller 22, e.g. by a wired or wireless communication link (not illustrated). The sensor units 20 may send measurement data to the controller 22 and / or receive control information from the controller 22 as required. The controller 22 may comprise any suitably configured computing device. Alternatively, when installed on the apparatus 10 the sensor units 20 may make and store measurements independently, and the resulting data may be uploaded transmitted or otherwise transferred to a computing device at a convenient time. In either case, the computing device may comprise any suitably programmed and / or configured computing device, e.g. a tablet computer, a smartphone, a laptop computer, a PC or a dedicated computing device. The controller 22 and / or other computing device, as applicable, may be programmed and / or otherwise configured to perform analysis of the measurement data as required by the application, e.g. in order to assess the operating performance and / or structural conditional of the apparatus 10. The analysis may be conventional and may vary from application to application. Typically, analysis of the measurement data is based on known or assumed characteristic(s) of each sensing unit 20, including any one or more of: the location of the sensor unit 20 with respect to the apparatus 10 or with respect to each other; the orientation of the sensor unit 20; and / or the alignment of the sensor unit 20 with respect to one or more reference axis and / or with respect to each other. In order to provide accurate analysis of the measurement data received from the sensor units 20, it is desirable that each sensor unit 20 is located in a desired location; oriented in a desired orientation; and / or aligned in a desired alignment with respect to one or more reference axis, and / or with respect to each other, as applicable for the analysis. Each sensor unit 20 comprises at least one vibration sensor 25 (Figure 4). The, or each, vibration sensor 25 may be of any conventional type, for example comprising one or more accelerometer, piezoelectric sensor or MEMs vibration sensing device. The sensor unit 20 may be of a type that senses vibrations along a single axis. Preferably, however, the sensor unit 20 is configured to sense vibrations along more than one axis, in particular more than one mutually perpendicular axis. It is particularly preferred that the sensor unit 20 is configured to sense vibrations along three mutually perpendicular axis (i.e. the X, Y and Z axes), which is commonly referred to as tri-axial vibration sensing and such sensors are commonly referred to as tri-axial vibration sensors or tri-axial accelerometers. This may be achieved in any conventional manner, for example using a respective vibration sensor oriented to sense vibrations along a respective axis, or using a single vibration sensor that is capable of sensing vibrations along multiple axes. When the sensor units 20 are mounted on the apparatus 10, it is desirable for the, or each sensing axis of each sensor unit 20 to be aligned correctly with respect to one or more reference axis (which may be an axis of the apparatus 10, e.g. the longitudinal, transverse and / or vertical axis of the apparatus 10, and / or global horizontal and / or vertical axes), or at least to be in a known disposition or alignment with respect to the relevant reference axis / axes. It is also desirable for the orientation of the sensor units 20, and therefore of the sensing axis, or axes, to be known with respect to the reference axis / axes or direction(s). It is desirable for the sensor units 20 to be in a known alignment and / or orientation with respect to each other. This may be derived from the known alignment and / or orientation, respectively, of the sensor units 20 with respect to the relevant reference axis or axes. For example, it may be desired to mount the sensor units 20 on the apparatus 10 such that the units 20 are all in the same orientation and / or so that the respective corresponding sensing axis, or axes, of each sensor unit 20 are parallel with each other. Each sensor unit 20 comprises a housing 30 that contains the sensor(s) 25 and any other electrical or electronic component(s) and / or circuitry required by the sensor unit 20, e.g. to support operation of the sensor(s) 25, for data storage and / or communication with the controller 22 or other computing device as required. The housing 30 may be referred to as the body of the sensor unit 20 and may take any suitable form, typically comprising a rigid enclosure or casing, and may be formed from any suitable material, e.g. plastics. The housing 30 is typically box-like in shape (in particular a generally square or rectangular box). With reference by way of example to the embodiment of Figure 4 in particular, the housing 30 typically comprises a base 30A and a lid 30B that can be removably fitted and fastened to the lid 30B. Any conventional fasteners may be used for this purpose, e.g. screws 31. An O-ring seal 32 may be provided between the base 30A and the lid 30B. The sensor(s) 25 and any other components may be provided on a printed circuit board (PCB) 33, which may be fastened to the housing 30 by any suitable fasteners, e.g. screws 34, nuts 35 and washers 36. The magnet(s) 24 may be fixed to the reverse face 37 of the housing 30. This may be achieved using any suitable fixing means, e.g. screws 38. In the illustrated embodiments, three magnets 24 are provided and are mutually spaced apart on the reverse face 37 of the housing 30. In alternative embodiments, there may be more or fewer magnets. In any event, it is preferred that the magnet(s) 24 are arranged in a manner that is non-symmetrical with respect to at least one major axis of the reverse face 37 of the housing 30. This arrangement helps to ensure that the sensor unit 20 is mounted on the apparatus 10 in the correct orientation, as is described in more detail below. The non-symmetry may be achieved by the size and / or position of the, or each, magnet 24. Byway of example, in the illustrated embodiments, the magnets 24 are mutually spaced apart in a triangular arrangement. In preferred embodiments, the front face 39 of the housing 30 includes a visual indication of the orientation of the sensor unit 20, in particular a visual indication of whether the sensor unit 20 is the right way up or upside down. The visual indication may take any suitable form, e.g. text, a graphic, a logo and / or a symbol. Preferably, the visual indication is provided on a plate or label that may be fixed to the front face 39, e.g. using adhesive or any other suitable fixing means, but may alternatively be formed directly on the front face 39. By way of example, in the embodiment of Figures 1A, 3A, 3B and 4, a label 29 is provided on the front face 39 that carries text and a logo. In preferred embodiments, the front face 39 of the housing 30 includes a visual indication that distinguishes each sensor unit 20 from the, or each, other sensor unit 20 of the monitoring system. The visual indication may take any suitable form, e.g. a colour, text, a graphic, a logo and / or a symbol. Preferably, the visual indication is provided on a plate or label that may be fixed to the front face 39, e.g. using adhesive or any other suitable fixing means, but may alternatively be formed directly on the front face 39. By way of example, in the embodiment of Figures 1 A, 3A, 3B and 4, the respective label 29 for each sensor unit 20 is differently coloured from the label 29 of the, or each, other sensor unit 20 of the system. The monitoring system includes a respective locating device 40 for each sensor unit 20. Each locating device 40 is configured to receive the respective sensor unit 20. The preferred arrangement is such that each locating device 40 and its respective sensor unit 20 fit together, or couple, with each other. Advantageously, each locating device 40 and the respective sensor unit 20 are each configured so that each sensor unit 20 can only be coupled with, fitted to, or otherwise received by the respective locating device 40. This may be achieved by providing each sensor unit 20 and its respective locating device 40 with corresponding mating formations, e.g. one or more set of corresponding male and female mating formations, that allow each sensor unit 20 to be coupled or fitted only to its respective locating device 40, i.e. not to any of the other locating device(s) 40 included in the monitoring system (at least when the sensor unit is in the correct orientation). In preferred embodiments, each locating device 40 is configured such that, when the respective sensor unit 20 is coupled thereto, the sensor unit 20 is in a desired alignment with respect to the apparatus 10, in particular such that the, or each, sensing axis is aligned in a desired manner. In preferred embodiments, the locating device 40 comprises a body 42 that is configured to receive the respective sensor unit 20. To this end, the body 42 preferably includes one or more seating formation 44, the, or each, seating formation 44 being configured (e.g. shaped, dimensioned and / or positioned, as required) to receive at least part of the respective sensor unit 20. The body 42 may comprise a plate or other structure in which the seating formation(s) 44 are formed, and may be formed from any suitable material, e.g. metal or plastics. In preferred embodiments, the, or each, seating formation 44 comprises an aperture, cut-out portion or recess formed in the body 42. Preferably, the, or each, seating formation 44 extends through the body 40 so that the relevant part(s) of the sensor unit 20 can pass through the body 42 when the sensor unit 20 is fitted to the locating device 40. Typically, the relevant part(s) of the sensor unit 20 that pass through the body 42 comprise the attachment means, e.g. magnet(s) 24, for attaching the sensor unit 20 to the apparatus 10. As a result, when the locating device 40 is mounted on the apparatus 10, the attachment means, e.g. magnet(s) 24, engage with, or otherwise are in contact with, the apparatus 10 in order to hold the sensor unit 20 in place on the apparatus 10, e.g. by magnetic force in the case of magnet(s) 24. As such, in preferred embodiments, the locating device 40 is not required to support the weight of sensor unit 20 when mounted on the apparatus 10, nor is it required to form the (removable) attachment between the sensor unit 20 and the apparatus 10. However, depending on the fit between the, or each, seating formation 44 and the relevant part(s) of the sensor unit 20 received by the or each seating formation 44, the locating device 40 may provide some support to the sensor unit 20 when fitted. In alternative embodiments, the, or each, seating formation may be recessed with respect to the body surface without extending though the body 42. Conveniently, the seating formation(s) 44 are configured such that, when the respective sensor unit 20 is coupled to the respective locating device 40, the sensor unit 20 is in the desired alignment with respect to the apparatus 10. When the sensor unit 20 is mounted on the apparatus 10, forces acting on the sensor unit 20 during use (in particular those caused by vibration of the apparatus 10, but also impact forces causes by debris or other external objects) can cause the sensor unit 20 to slip or otherwise move with respect to the apparatus 10, or even become detached from the apparatus 10. In preferred embodiments, each locating device 40 is configured to prevent, or at least reduce, slippage or movement of the respective sensor unit 20 with respect to the apparatus 10, and preferably to reduce the likelihood that the sensor unit 20 will become detached. This may be achieved by providing a fit between the, or each, seating formation 44 and the relevant part(s) of the sensor unit 20 received by the or each seating formation 44 that prevents or restricts movement (in particular lateral or vertical movement, i.e. movement that is in or parallel with the plane of the body) of the sensor unit 20 with respect to the locating device 40 and therefore with respect to the apparatus 10 when the locating device 40 is mounted on the apparatus 10. This may involve the, or each, seating formation 44 and the relevant part(s) of the sensor unit 20 received by the or each seating formation 44 being configured to engage with each other when the sensor unit 20 is fitted to the locating device 40, e.g. around their respective peripheries, for example being contiguous or substantially contiguous, or otherwise to provide a close fit. This may be achieved by providing the, or each, seating formation 44 and the relevant part(s) of the sensor unit 20 with matching shape and dimensions. In preferred embodiments, each locating device 40 includes a first mating formation 46 for mating, or coupling, with a corresponding first mating formation 48 provided on the respective sensor unit 20. Corresponding first mating formations 46, 48 are configured so that, when fitting the sensor unit 20 to a locating device 40, the first mating formation 48 will only mate, or couple, with the first mating formation 46 of the respective, i.e. the correct, locating device 40 (at least when the sensor unit 20 is in the correct orientation) and not with the first mating formation 46 of any other locating device 40 included in the system. The first mating formations 46, 48 therefore allow the sensor unit 20 to be fitted to the correct locating device 40 but not to any other locating device 40 included in the system (at least when the sensor unit 20 is in the correct orientation). Corresponding first mating formations 46, 48 may be configured for mutual coupling in any convenient manner, for example by their respective shape and / or size, or otherwise being provided as corresponding male and female mating formations. Preferably, corresponding first mating formations 46, 48 are configured for mutual coupling by their location on the locating device 40 and sensor unit 20 respectively. In preferred embodiments, each sensor unit 20 and corresponding locating device 40 include orientation means for ensuring that the sensor unit 20 is fitted to the locating device in the correct orientation. The orientation means may comprise a respective corresponding orientation formation 60, 62 provided on the sensor unit 20 and locating device 40 that fit together when the sensor unit 20 is fitted to the locating device in the correct orientation, but do not fit together when the when the sensor unit 20 is fitted to the locating device in an incorrect orientation (e.g. upside down), thereby preventing the sensor unit 20 from being fitted to the locating device 40. Alternatively, the orientation means may comprise a corresponding arrangement of the seating formation(s) 44 and the relevant part(s) of the sensor unit 20 received by the or each seating formation 44 such that the relevant 14 sensor unit part(s) and seating formation(s) fit together when the sensor unit 20 is fitted to the locating device in the correct orientation, but do not fit together when the when the sensor unit 20 is fitted to the locating device in an incorrect orientation (e.g. upside down), thereby preventing the sensor unit 20 from being fitted to the locating device 40. Unlike the mating formations 46, 48, the orientation means do not have to be unique or different for each pair of sensor unit 20 and locating device 40 of the monitoring system, i.e. they can be the same for each pair of sensor unit 20 and locating device 40 of the system. This simplifies the manufacturing requirements of the system. The orientation means are particular advantageous in embodiments where the respective mating formations 46, 48 for each pair of sensor unit 20 and locating device 40 do not exclude the possibility that a sensor unit 20 can be fitted to the wrong locating device 40 if it is in an incorrect orientation, e.g. if the sensor unit 20 is upside down, as is illustrated in the examples below. Figures 3A, 3B and 4 show a first embodiment of the sensor unit 20 and locating device 40. The locating device 40 has a single seating formation 44 in the preferred form of an aperture 44 formed in the body 42. The aperture 44 is shaped and dimensioned to receive the housing 30, in particular a rear portion of the housing 30 that includes the reverse face 37. The shape and dimensions of the aperture 44 preferably match the shape and dimensions of the rear portion of the housing 30 to provide a fit between the aperture 44 and rear portion that prevents or restricts movement or slippage of the sensor unit 20 with respect to the locating device 40 and therefore with respect to the apparatus 10 in use. The orientation formation 62 is provided at a periphery of the aperture 44 and the corresponding location formation 60 is provided at a periphery of the rear portion of the housing 30, the arrangement being such that, when the sensor unit 20 is in the correct orientation, the orientation formations 60, 62, which are preferably corresponding male and female formations, fit together to allow the rear portion of the sensor unit 20 to fit into the aperture 44. In this first embodiment the first mating formation 46 of the locating device 40 comprises a portion, conveniently a corner 46, of the mouth of the aperture 44 (which is typically generally rectangular in shape) that is shaped differently from the other corners of the aperture 44. In this example, the corner 46 is rounded and the other corners are right-angled. Each locating device 40 of the monitoring system has the mating formation 46 in a different location, which in this embodiment involves using a respective different corner of the aperture 44 as the mating formation 46. For example, for the preferred monitoring system comprising four sensor units 20A-20D, there are four corresponding locating device 40A (only one shown for the first embodiment). The lower right corner of the aperture 44 of the locating device 40A is shaped to provide the first mating formation 46. Each of the other locating devices 40 has a respective one of the lower left corner, upper right corner and upper left corner shaped to provide its first mating formation 46. In this first embodiment, first mating formation 48 of the sensor unit 20 comprises a corner 48 of the housing 30, or at least a corner of the rear portion of the housing 30 that is shaped differently from the other corners of the housing 30, or at least from the other corners of the rear portion of the housing 30. The corner 48 is typically shaped to match the corner 46 of the corresponding locating 15 device 40. The corner 48 is located on the sensor unit 20 at a location that matches the location of the corner 46 of the corresponding locating device 40, at least when the sensor unit 20 is in the correct orientation. For example, in Figure 4, the mating formation corner 48 of the sensor unit 20A is the lower right corner of the housing 30 when the sensor unit is correctly orientated. When the sensor unit 20A is fitted to the respective, i.e. correct, locating device 40 in the correct orientation, the respective mating corners 48, 46 align with each other and allow the sensor unit 20A to be fitted to the locator device 40, in particular such that the rear portion of the housing 30 fits into the aperture 44. However, the sensor unit 20A cannot similarly be fitted to one of the other locator devices 40 because the respective mating corners 48, 46 do not align and so the rear portion of the housing 30 does not fit into the aperture 44. It will be apparent that in alternative embodiments portions of the aperture 44 other than the corners may be used to provide the mating formations in which case corresponding parts of the rear portion of the housing 30 may be configured to provide the corresponding mating formations. Figures 5 to 14 show a second embodiment of the sensor unit 20 and locating device 40. The locating device 40 has a plurality of seating formations 44 in the preferred form of apertures 44 formed in the body 42. Each aperture 44 is shaped and dimensioned to receive a respective part of the sensor unit 20, in particular a respective rear portion of the sensor unit 20. The preferred arrangement is that each aperture 44 is configured to receive a respective magnet 24. In alternative embodiments there may be a single magnet 24 and so the locating device 40 may be provided with a single aperture 44, or other seating formation, shaped and dimensioned to receive the magnet 24. The shape and dimensions of the, or each, aperture 44 preferably match the shape and dimensions of the respective magnet 44 to provide a fit between the aperture 44 and respective magnet 24 that prevents or restricts movement or slippage of the sensor unit 20 with respect to the locating device 40 and therefore with respect to the apparatus 10 in use. The arrangement of the aperture(s) 44 matches the arrangement of the magnet(s) 24 to allow the sensor unit 20 and locating device 40 to fit together. The orientation means is preferably provided by the non-symmetrical arrangement of the magnet(s) 24 as described above, and the corresponding non-symmetrical arrangement of the aperture(s) 44. Accordingly, the sensor unit 20 only fits with the locating device 40 when in the correct orientation. In the second embodiment, the arrangement of apertures 44 and magnets 24 is the same for each locating device 40 and sensor unit 20 of the system. In alternative embodiments, each pair of sensor unit 20 and locating device 40 may have a respective different arrangement of aperture(s) 44 and magnet(s) 24. As such the aperture(s) 44 and magnet(s) 24 may serve as mating formations that allow each sensor unit 20 to be coupled with the respective locating device 40 but not with other locating device(s) 40 of the system. In the second embodiment, the first mating formation 46 of the locating device 40 comprises a locating aperture 46, or other female formation, that is differently located on each locating device 40 of the monitoring system. The locating aperture 46 is conveniently formed in the body 42, and may be a through-aperture or a blind aperture (e.g. a socket). Each locating aperture 46 is provided at a respective different location on the respective locating device 40 in comparison with the location of the respective locating aperture 46 on the other locating device(s) 40. In the example of Figures 9A to 12B, it can be seen that for the locating device of Figures 9A and 9B the locating aperture 46 is provided at the bottom right of the body 42; for the locating device of Figures 10A and 10B the locating aperture 46 is provided at the bottom left of the body 42; for the locating device of Figures 11A and 11B the locating aperture 46 is provided at the top left of the body 42; and for the locating device of Figures 12A and 12B the locating aperture 46 is provided at the top right of the body 42. It will be understood that in alternative embodiments, the locating apertures 46 may be located elsewhere on the locating device 40 as is convenient. Each sensor unit 20 is provided with a corresponding mating formation 48 in the preferred form of a locating pin 48 or other male mating formation. The locating pin 48 of each sensor unit 20 is provided at a respective location that matches the location of the aperture 46 on the corresponding locating device 40. When the sensor unit 20A is fitted to the respective, i.e. correct, locating device 40 in the correct orientation, the respective locating pin 48 and locating aperture 46 align with each other and allow the sensor unit 20A to be fitted to the locator device 40, which in the second embodiment involves the magnets 24 fitting into the respective aperture 44. However, the sensor unit 20A cannot similarly be fitted to one of the other locator devices 40 because the respective locating pin 48 and locating aperture 46 do not align. It will be understood that other forms of male and female mating formations may be used, respectively, instead of the locating pin 48 and locating aperture 46, and that the respective corresponding male and female mating formations may be provided on either one of the sensor unit 20 and locating device 40 as is convenient. It will be apparent from the foregoing that in preferred embodiments each pair of sensor unit 20 and locator device 40 included in the monitoring system has a respective different mating configuration that allows each sensor unit 20 to be fitted to or otherwise received by its respective locating device 40 (at least when the sensor unit 20 is in the correct orientation) but not to any other locating device 40 of the system. In the examples above, the different mating configurations comprise, at least in part, the respective different arrangement of, and in particular the respective different location of, the respective first mating formations 46, 48. Preferably, each sensor unit 20, in particular the housing of the sensor unit 20, is configurable to adopt any one of a plurality of different mating configurations, in particular any one of the different mating configurations used by the monitoring system of which it is part. This configuration may be achieved by modifying each sensor unit 20, conveniently the housing 30, in a different way. Advantageously, each sensor unit 20, in particular the housing 30, is provided in a standard form, e.g. manufactured to be the same as each other, that is amenable to modification to adopt any one of the different mating configurations. This simplifies the manufacturing requirements of the system. For example, in the embodiment Figures 3A, 3B and 4, the housing 30 of each sensor unit 20 comprises a plurality of sacrificial or removable (e.g. perforated or frangible) formations 68 (e.g. tabs), which in this example are provided at each corner of the housing 30. For each sensor unit 20 of the monitoring system, a respective different one of the formations 68 is removed, resulting in each housing 30 having a different shape and thus a different mating configuration. For example, in Figure 3B the formation 68 has been removed from the lower right corner to provide the sensing unit 20 with its first mating formation 48, which in this example comprises a rounded corner. Configuring each sensor unit 20 to have a different mating configuration makes the sensor units 20 location specific. In the embodiment of Figures 5 to 14, the housing 30 of each sensor unit 20 comprises a plurality of sockets 49 for receiving the locating pin 48, a respective socket 49, or other female formation, being provided at each location that corresponds to the locations of the locating apertures 46 of the locating devices 40 of the system. For each sensor unit 20 of the monitoring system, the locating pin 48 is inserted into a respective different one of the sockets 49, resulting in each sensor unit 20 having a differently located locating pin 48 and thus a different mating configuration. For example, in Figure 5 the locating pin 48 has been inserted into the lower left socket 49 (as viewed in Figure 5) to provide the sensor unit 20 with its first mating formation 48. The sensor unit 20 of Figure 5 is therefore adapted to fit together with the locating device 40 of Figure 6 (which has its locating aperture 46 in a lower right position), but not with the other locating devices 40 of the system. Configuring each sensor unit 20 to have a different mating configuration makes the sensor units 20 location specific. Optionally, each locating device 40, for example the body 42 of the locating device 40, is configurable to adopt any one of a plurality of different mating configurations, in particular any one of the different mating configurations used by the monitoring system of which it is part. This configuration may be achieved by modifying each locating device in a different way. Each locating device 40 may be provided in a standard form, e.g. manufactured to be the same as each other, that is amenable to modification to adopt any one of the different mating configurations. This simplifies the manufacturing requirements of the system. For example, the body 42 of each locating device 40 may comprises a plurality of sacrificial or removable (e.g. perforated or frangible) formations (e.g. tabs), which for example may be provided at each corner of the aperture 44 (especially in embodiments where there is a single aperture 44). For each locating device 40 a respective different one of the formations 68 is removed, resulting in each aperture 44 having a different shape and thus a different mating configuration. Alternatively, in embodiments such as that illustrated in Figures 5 to 14, the body 42 may be provided with a respective blind aperture (i.e. an aperture covered or blocked by a sacrificial membrane or other sacrificial formation) in each location for the locating apertures 46, whereby for each locating device 40 of the system a respective different blind aperture is modified, e.g. to become a through-aperture, to serve as the respective locating aperture 46. Referring in particular to Figures 13 and 14, the locating devices 40 may be fixed to the apparatus 10 using any suitable fixing means, e.g. screws 65 or bolts. Since each locating device 40 is configured to fit with a respective one of the sensor units 20, and since each sensor unit 20 is intended for use at a particular respective location on the apparatus 10, it is important that the locating devices 40 are 18 located correctly on the apparatus 10. To this end, each locating device 40 may be provided with a respective different arrangement of fixing aperture(s) 64 for receiving fixing devices such as screws 65. Typically, each locating device 40 has more than one fixing aperture 64, each locating device 40 having a respective different arrangement, e.g. spatial arrangement, of fixing apertures 64. For example, in Figures 9B, 10B, 11B and 12B, the respective locating device 40 has three fixing apertures 64 with a spatial arrangement that is different from the spatial arrangement of the fixing apertures 64 of the other locating devices 40. Corresponding fixing apertures 66 are provided at the desired respective location on the apparatus 10 such that each locating device 40 may be fixed only to its respective, or correct, location on the apparatus 10. Preferably, the corresponding fixing apertures 64, 66, or other fixing means, are arranged such that the respective locating device 40 is oriented and aligned in the desired manner with respect to the apparatus 10. In preferred embodiments, each locating device 40 is fixed to the apparatus 10 at the desired respective location and in the desired orientation and alignment with respect to the apparatus 10. Therefore, when the sensor units 20 are fitted to the respective locating device 40, each sensor unit 20 is located in its desired location, oriented in its desired orientation, and aligned in a desired alignment with respect to one or more reference axis. As such, the sensor units 20 are in a desired, or known, location, orientation and alignment with respect to each other. In preferred embodiments, each locating device 40 includes a protective guard 50 for shielding the sensor unit 20 when fitted to the locating device 40. The guard 50 may comprise a flange or other structure that projects outwardly from the body 42, preferably perpendicularly. The guard 50 preferably extends along the top of the body 42, or may be otherwise located such that projects over the sensor unit 20 when fitted to the locating device 40, preferably along the entire length of the sensor unit 20. In embodiments in which the body 42 comprises a plate, the guard 50 may comprise a folded top portion of the plate. In use, the guard 50 shields the sensor unit 20 from above, thereby providing protection against impacts and contamination from falling debris and from dirt and dust accumulation that could adversely affect the operation of the sensor unit 20. It is preferred not to provide similar guards at the sides of the body 42 or at the bottom of the body 42 to reduce potential interference with the operation of the sensor unit 20, in particular wireless communication to and from the sensor unit 20. In preferred embodiments, the system ensures that the sensor units 20 are consistently fitted to desired screen locations at initial fitting, after removal for charging, cleaning or one-off testing. The preferred system facilitates generation of directly comparable data across different screening apparatus, or other vibratory apparatus. Preferably, the locating devices 40 can only be fitted to a designated screen location and only accept the respective sensor unit 20 assigned to the respective designated screen location. Typically, the locating devices 40 are fitted to the apparatus 10 at the time of manufacture. The sensor units 20 can be fitted and removed as required. The sensor units 20 may be assigned to any suitable location on the apparatus 10, e.g. feed / inlet end left, feed / inlet end right, discharge / outlet end left, discharge / outlet end right. The sensor units 20 may be used with a CM single apparatus 10, or may be used with multiple different apparatus 10. The locating devices 40 ensure that the sensor units 20 are correctly aligned relative to one another and relative to screen / apparatus geometry. This facilitates making best use of data collected in the three orthogonal axes, e.g. static acceleration data for angle measurements or dynamic vibration data for accessing 5 screen performance or screen structural behaviour. Advantageously, the locating devices 40 ensure that the sensor units 20 remain in position in the event of magnetic mount capacity overload, debris strikes, screen-box overloads, or other human or mechanical interference. Advantageously, the locating devices 40 offer protection from a demanding working environment, impact and contamination protection and from falling debris and also dirt and dust accumulation that could 10 potentially attenuate sensor wireless signal or impede sensor operation. The invention is not limited to the embodiment(s) described herein but can be amended or modified without departing from the scope of the present invention as defined by the claims appended hereto.

Claims

1. A monitoring system for a vibrating apparatus, the system comprising:a plurality of locating devices for fixing to a respective location on said apparatus;a plurality of sensor units for releasably fitting to said locating devices, each sensor unit comprising at least one vibration sensor, wherein each locating device and a corresponding one of said sensor units have a respective mating configuration for enabling the corresponding sensor unit to be fitted to the respective locating device, and wherein the respective mating configuration of each locating device and the corresponding one of said sensor units is different from the respective mating configuration of the, or each, other locating device and corresponding one of said sensor units.

2. The system of claim 1, wherein the respective mating configuration comprises a mating formation provided on the locating device and a corresponding mating formation provided on the corresponding sensor unit.

3. The system of claim 2, wherein the location of the mating formation on the locating device and the location of the corresponding mating configuration on the sensor unit are different for each locating device and corresponding sensor unit.

4. The system of claim 2 or 3, wherein each locating device is configurable such that the mating formation has any one of a plurality of mating formation configurations so that said locating device is compatible with any one of said mating configurations.

5. The system of claim 4, wherein said plurality of mating formation configurations comprises a plurality of different locations on said locating device, each locating device being configurable such that the mating formation is located at any one of said locations.

6. The system of claim 4 or 5, wherein each locating device includes a plurality of sacrificial formations and is configurable to adopt any one of said mating formation configurations by removal or destruction of a respective one of said sacrificial formations.

7. The system of claim 4 or 5, wherein each locating device includes a plurality of female formations configured to receive a male mating formation, said female formations preferably being provided at a respective different location on the locating device.

8. The system of any one of claims 2 to 7, wherein each sensor unit is configurable such that the mating formation has any one of a plurality of mating formation configurations so that said sensor unit is compatible with any one of said mating configurations.

9. The system of claim 8, wherein said plurality of mating formation configurations comprises a plurality of different locations on said sensor unit, each sensor unit being configurable such that the mating formation is located at any one of said locations.

10. The system of claim 8 or 9, wherein each sensor unit includes a plurality of sacrificial formations and is configurable to adopt any one of said mating formation configurations by removal or destruction of a respective one of said sacrificial formations, said sacrificial formations preferably being provided at a respective different location on the sensor unit.

11. The system of claim 8 or 9, wherein each locating device includes a plurality of female formations configured to receive a male mating formation, said female formations preferably being provided at a respective different location on the sensor unit.

12. The system of any one of claims 2 to 11, wherein the respective mating formation of each locating device comprises an aperture, or other female formation, provided at a respective different location in the respective locating device, the respective corresponding mating formation of each sensor unit comprising a locating pin, or other male formation, provided at a respective different location that matches the location of the aperture, or other female formation, on the corresponding locating device to allow each sensor unit to be fitted to the respective locator device.

13. The system of any one of claims 2 to 11, wherein the respective mating formation of each locating device comprises a respective different corner, or other differently located part, of the mouth of a seating aperture for receiving the respective sensor unit, the respective corresponding mating formation of each locating device comprising a respective different corner, or other corresponding differently located part, of a portion of said sensor unit that is received by said seating aperture when the sensor unit is fitted to the respective locator device.

14. The system of any preceding claim, wherein the respective mating configuration is configured to enable the corresponding sensor unit to be fitted to the respective locating device but not to the, or each, other locating device, at least when the sensor unit is in a desired orientation.

15. The system of any preceding claim, wherein each locating device comprises a body including one or more seating formation configured to receive one or more part of the respective sensor unit when the senor unit is fitted to the locating device, the or each seating formation preferably comprising an aperture, cut-out portion or recess formed in the body.

16. The system of claim 15, wherein the, or each, seating formation extends through the body so that said one or more part of the sensor unit passes through the body when the sensor unit is fitted to the locating device.

17. The system of claim 16, wherein said one or more part of the sensor unit that passes through the body comprises attachment means for attaching the sensor unit to the apparatus, said attachment means preferably comprising one or more magnet.

18. The system of any one of claims 15 to 17, wherein the, or each, seating formation is configured to fit with the respective part of the sensor unit such that movement of the sensor unit with respect to the locating device is restricted.

19. The system of any one of claims 15 to 18, wherein each locating device has a single seating formation formed in the body, the single seating formation being shaped and dimensioned to receive a rear portion of the respective sensor unit.

20. The system of any one of claims 15 to 18, wherein each locating device has a plurality of seating formations formed in the body, each seating formation being shaped and dimensioned to receive a respective part of the sensor unit.

21. The system of claim 20, wherein a plurality of attachment magnets are provided on the rear portion of the sensor unit, each seating formation being configured to receive a respective magnet.

22. The system of any preceding claim, wherein each sensor unit and corresponding locating device include orientation means for ensuring that the sensor unit is fitted to the locating device in a desired orientation.

23. The system of claim 22 when dependent on any one of claims 15 to 21, wherein the orientation means comprises a corresponding arrangement of the, or each, seating formation and of said one or more part of the sensor unit, such that the, or each, seating formation and said one or more part of the sensor unit only fit together when the sensor unit is fitted to the locating device in the correct orientation.

24. The system of any preceding claim, wherein each locating device is provided with a respective different arrangement of fixings or fixing apertures by which the locating device may be fixed to the apparatus.

25. The system of any preceding claim, wherein each locating device includes a protective guard for shielding the sensor unit when fitted to the locating device.

26. A screening apparatus or other vibrating apparatus adapted to include a monitoring system as claimed in any preceding claim, the screening apparatus or other vibrating apparatus comprising said plurality of locating devices fixed to a respective location on said screening apparatus for removably receiving the respective sensor unit.

Images