WO2009047719A2

WO2009047719A2 - A method, apparatus and system for monitoring the winding of rope about a drum

Info

Publication number: WO2009047719A2
Application number: PCT/IB2008/054127
Authority: WO
Inventors: Herbert Schmitz
Original assignee: Herbert Schmitz
Priority date: 2007-10-11
Filing date: 2008-10-08
Publication date: 2009-04-16
Also published as: WO2009047719A3; ZA201002034B

Abstract

The invention relates to a method (100), apparatus (20) and system (21) for monitoring winding of rope (14) about a drum (38) of a winder (13). The method (100) includes sensing (102) by means of at least one sensor (22, 24) at least one characteristic of the rope (14) in a region of operative winding of the rope (14) onto the drum (38) during rotation of the drum (38) and capturing (104) the characteristic in real-time via the sensor (22, 24) during winding of the rope (14) onto the drum (38). The method (100) further includes comparing (106) the captured characteristic against predefined winding criteria associated with normal winding of the rope (14) and determining (110) that bad coiling has occurred in response to the captured characteristic violating the winding criteria.

Description

A method, apparatus and system for monitoring the winding of rope about a drum

FIELD OF INVENTION

THIS INVENTION relates generally to winding of rope about a drum and specifically to a method, apparatus and system for monitoring the winding of rope about a drum.

BACKGROUND OF THE INVENTION

The Inventor is aware of winders, such as those typically used in mines, which include at least one rope drum (and potentially two rope drums) about which wire rope or a like elongate flexible element, typically attached to the drum, can be wound. A conveyance or cage is attached to a free end of the rope so that rotation of the drum raises or lowers the conveyance in a mineshaft. The winding arrangement can be configured to include two complemental conveyances such that one is raised while the other is lowered.

Some mines include very deep mine shafts and, consequently, associated mine winders include long lengths of rope which can exceed 1 km in length and typically has a large gauge or diameter to accommodate the weight of the conveyance containing personnel or excavated material as well as the weight of the rope itself. Operational speeds may exceed 10 m/s and it is possible that the rope may wind or coil about the drum irregularly (further referred to as "bad coiling").

Under normal operational conditions, the rope coils helically from one end of the drum to the other and then coils back on itself in the opposite direction. Bad coiling occurs when the coiling direction reverses and the rope coils back on itself before it has reached an end of the drum. This is undesirable as it may cause the rope to jolt and a radius of the coiled rope will change more drastically or sooner than anticipated by the winder control system. This sudden change can cause an unanticipated increase in velocity and/or position of the conveyance travelling along the mineshaft which, if not timeously detected, can cause the conveyance to become jammed in the head gear of the shaft.

This can lead to a violent jamming causing the rope end to tear and become disconnected from the conveyance. In such case, the conveyance will fall down the shaft (where it will hopefully be caught by jack catches) while the loose end of the rope is sent flailing through the headgear to the winder housing causing severe property damage and human injuries or fatalities. The contents of the fallen conveyance may be damaged or injured and may become dislodged so that they fall down the mineshaft below causing further damage.

The Inventor desires to eliminate or at least alleviate the above-mentioned disadvantages.

SUMMARY OF INVENTION

Accordingly, the invention provides a method of monitoring winding of rope about a drum of a winder, the method including: sensing by means of at least one sensor at least one characteristic of the rope in a region of operative winding of the rope onto the drum during rotation of the drum; capturing the characteristic in real-time via the sensor during winding of the rope onto the drum; comparing the captured characteristic against predefined winding criteria associated with normal winding of the rope; and determining that bad coiling has occurred in response to the captured characteristic violating the winding criteria.

In the context of this specification, "rope" includes cables, wires and like elongate tensile elements whether of metal, synthetic or natural fibres, or other material. "Drum" includes any spool or reel about which such a rope can be wound.

Sensing the at least one characteristic may include directing a plurality of sensors towards the rope. The sensors may be arranged side-by-side and spaced axially along the length of the drum. The sensor may be an optical sensor and, in such case, capturing the characteristic may include capturing at least one image of the rope. Capturing the characteristic may include capturing a video or a series of sequential images.

Sensing the at least one characteristic may include directing the optical sensor tangentially towards the rope. The method may further include determining respective radii or heights of various sections of coiled rope. The characteristic of the rope being captured may thus be a difference in radius between exposed layers (e.g. by using so-called edge-detection). In such case, which the winding criteria may dictate that respective radii of innermost and outermost layers of coils may differ by no more than one rope diameter.

It is to be appreciated that during normal coiling, there will be at most two sections of coiled rope which differ in height and then by one rope diameter only. A first, inner section is defined by an underlying completed coil (coiled from one end of the drum to the other) while a second, outer section is defined by a partially completed overlying coil progressing in an opposite direction between the ends of the drum. The inner section will have a radius which is one rope diameter smaller than a radius of the outer section. Once the outer section is complete (i.e. it reaches one end of the drum) there will be for a moment only one visible coiled section before the process repeats itself in the other direction. If bad coiling has occurred (e.g. if the rope has begun coiling back on itself before it reached the end of the drum) there may be at least three sections of coiled rope and the outer and inner sections may differ by at least two rope diameters.

Instead, or in addition, the characteristic of the rope being captured may be a coordinate of an outer edge of rope of each of a plurality of axially spaced points. In such case, the winding criteria may dictate that no more than one coordinate may differ by no more than a predefined amount from an average.

Sensing the at least one characteristic may include directing the optical sensor inwardly toward the rope. The method may further include determining irregular changes in pattern of coiled sections (e.g. a number of places where visible coiled sections of rope overlap or an irregular change in pitch or inclination of the rope). The characteristic being captured may be a variable pattern defined by the rope during winding. The winding criteria may then dictate that a coiling pattern may change no more than once. During normal coiling, as described above, there will be an inner section and an outer section and these sections will overlap in no more than one place and usually will have a generally consistent inclination. The coil of the inner section will be inclined in one direction (e.g. clockwise), while the coil of the outer section will be inclined in the other direction (e.g. counter-clockwise). If bad coiling has occurred, there may be three or more sections which overlap in two or more places. In such case, the direction of coiling may change at least twice (e.g. clockwise to counter-clockwise to clockwise), may not change direction where expected and/or the coiling pattern (e.g. pitch) may vary.

Instead, or in addition, the characteristic being captured may be a thickness of each visible coil of rope. In such case, the winding criteria may dictate that respective thicknesses of the visible coils differ by a tolerance from an average no more than once.

The method may further which includes providing at least one acoustic sensor proximate the drum, in which the captured characteristic is a sound of the rope as it is wound about the drum, the sound being captured by the at least one acoustic sensor. The winding criteria may then include predefined acoustic waveforms. "Proximate the drum" includes being sufficiently close to the drum to receive or hear sounds but not necessarily attached to or even adjacent of the drum.

The method may include responding automatically in accordance with predefined response criteria upon determining that bad coiling has occurred. The response criteria may direct that an alarm is raised in response to a determination of bad coiling. The alarm may include at least one of a visible alarm (e.g. a flashing light or pop-up window on a computer), and an audible alarm (e.g. from a buzzer or siren). The response criteria may direct that the winder be shut down and thus the method may include automatically shutting down the winder in response to determining that bad coiling has occurred. Instead, or in addition, the method may include automatically correcting or normalising the winding of the rope.

The method may include the prior step of storing or amending at least one of the winding criteria and the response criteria.

The invention extends to an apparatus for monitoring winding of rope about a drum of a winder, the apparatus including: at least one sensor operable to capture at least one characteristic of the rope as it is wound about the drum; a memory module having stored thereon predefined winding criteria; and an electronic control module in communication with the sensor, the control module being operable to: compare the captured characteristic against the predefined winding criteria; and determine that bad coiling has occurred in response to violation by the captured characteristic of the winding criteria

The apparatus, in use, may be positioned proximate or fixed to the winder. In this regard, the apparatus may be mobile, for example being separate from the winder and being movable from one winder to another. Alternatively, the apparatus may be integral with the winder, being permanently affixed thereto. If desired, the apparatus may include mounting means for mounting the apparatus in a calibrated position relative to the winder.

In one embodiment, the sensor may include at least one optical sensor and may in fact include a plurality of optical sensors. The optical sensors may, in use, be directed at axially spaced apart locations on or near the drum to capture images of the rope as it winds around any part of the drum.

Optical sensors may be in the form of cameras which are operable to capture a plurality of sequential images or video. In the case of a video camera, it may be configured to capture video having a high resolution and/or a high frame rate, whether digital or analogue, whether colour or monochrome. A lens of the video camera may be a high clarity lens calculated optimally to capture video in its field of view.

The control module may be operable to determine respective radii or heights of various layers of coiled rope. Instead, or in addition, the control module may be operable to determine irregular changes in pattern of coiled layers.

In another embodiment, the sensor may instead or in addition be in the form of an acoustic sensor to record a sound of the rope as it is wound around the drum. The acoustic sensor may be in the form of a microphone having a high sensitivity and wide acoustic range and which may, in use, be focused towards the winding area of the drum.

The apparatus may include a processor. More particularly, the control module may be a conceptual module corresponding to a functional task performed by the processor. In such case, the apparatus may include a machine-readable medium, e.g. main memory, a hard disk drive and/or the processor itself, which carries thereon a set of instructions to direct the operation of the processor. It is to be understood that the apparatus may include one or more microprocessors, controllers, DSMs (Digital Signal Modules), or any other suitable computing device, resource, hardware, software, and/or embedded logic.

The apparatus may thus be embodied, at least partially, by a computer system. The apparatus may therefore include a graphical user interface, such as a display screen, and an input arrangement, such as a keyboard and/or mouse.

For example, the cameras may be directed generally tangentially (relative to the drum) towards the winding rope thereby to capture height differences of various coiled sections of the rope (as defined above). The control module may then be operable to determine that bad coiling has occurred in response to a height difference of two or more rope diameters.

In another example, the cameras may be directed generally readily inwardly towards the drum thereby to capture the pattern of the coiled rope. The control module in such case may include a pattern recognition engine therefore being operable to detect any irregular or anomalous coil patterns (as defined above).

The microphone may record any irregular sound (such as grinding, slipping or the like).

The apparatus may include response criteria, for example stored on the machine readable medium, governing a response of the apparatus once the control module has determined that bad coiling has occurred.

The response criteria may dictate that the apparatus, under direction of the control module, raises an alarm by means of an alarm arrangement (e.g. sounds a siren, flashes a warning light, or the like), shuts down the winder, and/or attempts to correct the bad coiling.

The apparatus may include a bus or other communication interface to interconnect the sensors (cameras and/or microphones), the control module and the machine readable medium. The bus may accommodate digital triggering, and analogue signals and/or industrial bus protocols and may also interconnect the apparatus with a pre-existing winder control system.

The controller and/or the criteria (winding and/or response criteria) may be programmable or configurable via the user interface and input arrangement thereby to configure the operation of the apparatus.

The invention extends to a system which includes: a winder having a drum which is rotatable about a winding axis to wind rope about the drum; and an apparatus as defined above operatively associated with the winder.

The apparatus may be retrofitted to the winder or may be manufactured together with the winder. The invention extends to a machine readable medium embodying instructions which, when executed by a machine, cause the machine to perform a method as above defined.

BRIEF DESCRIPTION OF DRAWINGS

The invention will now be further described, by way of example, with reference to the accompanying diagrammatic drawings.

In the drawings: Figure 1 shows a schematic side elevational view of a mine including a winder;

Figure 2 shows a schematic view of a system including an apparatus in accordance with the invention;

Figures 3a - 3h show schematic views of a plurality of winders including normal coiling and bad coiling; Figures 4a - 4h show schematic views of an example of how the apparatus of

Figure 2 can determine whether or not bad coiling has occurred;

Figures 5a - 5h show schematic views of another example of how the apparatus of Figure 2 can determine whether or not bad coiling has occurred;

Figures 6a - 6h show schematic views of a further example of how the apparatus of Figure 2 can determine whether or not bad coiling has occurred;

Figures 7a - 7h show schematic views of a still further example of how the apparatus of Figure 2 can determine whether or not bad coiling has occurred; and

Figure 8 shows a flow diagram of a method of monitoring winding of rope about a drum, in accordance with the invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENT

Figure 1 shows a vertical shaft mine 10 which includes a winder house 12 having two complemental winders 13 (one of which is shown). Each winder 13 includes a drum 38 (see Figures 2 and 3) which is rotatable by means of a motor (not illustrated) about a rotational axis 13.1 to wind rope 14 about (i.e. onto and off of) the drum 38. The rope 14 extends down the mine shaft 16 and a cage 18 or other conveyance is connected to a remote or free end of the rope 14. By way of example, the mine 10 could be one of those much used in gold mining where shafts 16 can reach great depths. The rope 14 must therefore be sufficiently long and have a sufficient tensile strength to support both itself and an occupied cage 18 and the dynamic loads applied thereto. Some winders are configured to draw in or let out the rope 14 at a speed of over 10 m/s.

Referring now also to Figure 2, a system in accordance with the invention is generally indicated by reference numeral 20 and includes two complemental winders 13 interconnected by a common axle 40 and an apparatus 21 , in accordance with the invention, for monitoring the winding of the rope 14 about the drum 38 of each winder

13.

Referring also to Figure 8, which illustrates a method 100 in accordance with the invention, the apparatus 21 provides, at block 102, sensors in the form of a bank of cameras 22 and a microphone 24 associated with each winder 13. The sensors 22, 24 are operable to capture or record, at block 104, winding characteristics of the winders 13 in use. More particularly, the cameras 22 capture images. In this example, the cameras 22 are video cameras and are spaced axially relative to the drum 38. Instead, there may be a single camera which covers an entire axial width of a drum 38.

The sensors 22, 24 are arranged proximate their respective associated winders 13. The winders 13 are standard winders and do not necessarily need to be modified for use with the apparatus 21 in accordance with the invention. The cameras 22 are directed either tangentially towards the rope 14 (i.e. towards an edge of the coils) or inwardly toward the rope (e.g. generally towards the winding axis 13.1 of the drum 38).

The sensors 22, 24 are in communication with an electronic control module 28 via high-speed bus arrangements 26. The electronic control module 28 is operable to compare, at block 106, the captured characteristic (video and audio) against predefined winding criteria. To this end, the apparatus 21 includes a machine readable medium in the form of a memory module 30 having stored thereon the winding criteria. Although not explicitly illustrated, the electronic control module 28 may be in the form of a processor (as above defined) and the memory module 30 will then accordingly include a set of instructions or a computer program to direct the operation of the processor.

If any of the captured characteristics violate, at block 108, the winding criteria, the control module 28 determines, at block 1 10, that bad coiling has occurred.

The apparatus 21 further includes response criteria (also stored on the memory module

30) which dictate how the apparatus 21 responds to a determination of bad coiling. In this example, the response criteria direct that an alarm is to be raised in response to a determination of bad coiling. The apparatus 21 thus includes an alarm arrangement 32 in the form of a siren and a warning light. The control module 28 is also connected to the existing winder control mechanism 34 responsible for controlling the operation of the winders 13 so that the control module 28 can direct that the winders 13 be shut down automatically if bad coiling is detected.

Although not illustrated, the apparatus 21 could include a user interface and input arrangement (such as a computer screen and keyboard) via which the response criteria and/or the winding criteria may be edited as desired.

Figures 3a - 3h illustrate, in general terms, an example of how bad coiling can occur. The rope 14 is wound about the drum 38 from one end to the other and back again in successive layers of coils. "Coil" is understood to include a single winding of the rope 14. Each coil of a particular layer has a constant radius and when a particular layer has been completed, the next layer will have a larger radius and will be wound around the previous layer in an opposite direction. In Figure 3a, a layer of coils 50, which was formed from left to right, is completed and layer 52 is a partial layer which is being wound, from right to left, around the underlying layer 50. In Figure 3b, the layer

52 has been completed and obscures the underlying layer 50 entirely. In Figure 3c, a layer 54 is being wound around the completed layer 52 (an opposite direction) which now forms the underlying layer. The layer 54 should be completed entirely before a successive overlying coil is started.

However, as Figure 3d illustrates, halfway through the layer 54, the direction of coiling gets reversed and a new layer 56 begins. This is undesirable and is an example of bad coiling. The layer 56 usually continues over the partial, underlying layer 54 until it reaches the end of the drum 38 at which point a new layer 58 is started around layer 56. Roughly half of the completed layer 52 is still exposed and there is a marked difference in the radius of the layers 52, 58.

Once the layer 58 reaches the start of the layer 56 (the underlying coils), the rope 14 forms a new layer 60 (having the same radius as the layer 54). One drawback of bad coiling is that the radius of a particular layer or layer section increases sooner than expected and the winder control mechanism may not be able to compensate for this. Thus, if the drum 13 is rotating at a calculated speed about the winding axis 13.1 but a radius of the active coiling layer is larger than intended, the rope 14 will be fed out or drawn in at a quicker rate. Additionally, when the radius of the current coil decreases rapidly, for example when the layer 58 becomes the layer 60, the cage 18 may jolt or shudder.

Referring now to Figures 4a - 4h, an example of how the apparatus 21 , under direction of the control module 28, can visually detect the presence of bad coiling is illustrated. During normal coiling (Figures 4a - 4c), the difference in radius between any two visible layers of coils will be at most one diameter D of the rope 14. Also, because there is only one place of visible overlap, the radius changes only once.

The control module 28 is configured to detect the lines or outlines of the respective layers of rope 14. Thus, the cameras 22 are directed tangentially towards a portion of the winder 13 where the rope 14 is being wound. The control module 28 analyses in real-time individual frames of the video captured by the cameras 22 using edge detection by trying to create one or more lines or levels, respectively inline with the visible layers.

Using Figure 4d as an example, the control module 28 determines by means of edge detection that the radius of layer 52 differs by two rope diameters D (winding criteria) from the radius of layer 56. The winding criteria in the example dictate that the difference in radius of the innermost and outermost layers may differ by no more than one rope diameter D. The control module 28 therefore determines that bad coiling has occurred and accordingly activates the alarm arrangement 32 to make an operator aware of the bad coiling and also stops the winder 13 to limit potential damage. Alternatively, the control module 28 can be configured to detect that the radius changes in two places, i.e. between the layers 52 and 54 and the layers 52 and 56. This also indicates that bad coiling has occurred, and the winding criteria could be defined accordingly.

Similar considerations apply to Figures 4e - 4h. In fact, the respective radii of different layers may differ by up to three rope diameters D.

Referring now to Figures 5a - 5h, another example is illustrated, which is conceptually similar to that of Figures 4. Instead of detecting lines (as in Figure 4), the control module 28 is configured to detect discrete coordinates.

The control module 28 scans for distinct edges, using edge detection, along a plurality of predefined lines 62. The scanning lines 62 are axially spaced (i.e. spaced along the x-axis) while the scanning direction is radial (i.e. along the y-axis). Thus, the coordinates 50.1 , 52.1 , 54.1 , 56.1 of a plurality of sampling lines 62 are determined.

The resolution, for example the exact number of coordinates (or, conversely, the spacing between the coordinates), can be adjusted as desired, and preferably balanced between reliability and sensitivity.

It is specifically the y-value of the coordinates 50.1 , 52.1 , 54.1 , 56.1 which is of interest. In this example, the y-values of all of the coordinates 50.1 , 52.1 , 54.1 , 56.1 are summed and divided by the number of coordinates, thereby to determine an average value. If a particular coordinate 50.1 , 52.1 , 54.1 , 56.1 deviates from the average by more than a predefined amount (e.g. the rope diameter D), the control module 28 determines that bad coiling has occurred and takes appropriate action.

In Figure 5a, two sections 50, 52 are visible and the coordinates 50.1 , 52.1 are determined. The average y-value of the coordinates 50.1 , 52.1 will be somewhere in between the y-value of the coordinates of 52.1 of the section 50 and the y-value of the coordinates 52.1 of the section 52. The individual coordinates 50.1 , 52.1 will differ from the average by roughly half a rope diameter D, indicating that they bad coiling has not occurred.

In Figure 5d, however, there are three visible sections 52, 54, 56. Following the same methodology, the y-value of coordinate 56.1 will differ from the average y- value by more than a rope diameter D, and the control module 28 will then determine the bad coiling has occurred. Similarly, the control module 28 would determine that bad coiling has also occurred in any of Figures 5e - 5h.

Referring now to Figures 6a - 6h, another method of determining bad coiling is illustrated. During normal winding (Figures 6a - 6c), there should be at most one visible place of overlap (generally indicated by reference numeral 70). As described above, the presence of three or more visible layers indicates that bad coiling has occurred. The cameras 22 are directed radially inwardly towards the drum 13 so that the rope 14 is viewed generally transversely to its length. The field of view of the cameras 22 is generally indicated by reference numeral 72. The control module 28 includes a pattern recognition/matching engine, including a plurality of predefined patterns or images, to detect irregular changes in pattern which are indicative of bad coiling.

One example of a pattern to which the control module 28 is responsive is an unexpected change in the direction and/or a change in the pitch of the coils. In this embodiment, however, the control module 28 is operable to detect portions of a coil which are partially covered by an overlying coil and are thus only partially visible. For example, the partially completed layer 52 overlaps the underlying complete layer 50. At a place 70 spaced from the ends of the drum 13 where the layer 52 ends to expose the underlying layer 50, an individual coil of the underlying layer 50 will be partially covered (by the overlying partial layer 52) and partially visible. Under normal coiling conditions, there will be at most one partially covered coil (often having a generally V-shaped appearance).

In Figures 6d - 6h, there are two or more partially covered coils or the coil is covered in an irregular manner. The pattern recognition engine of the control module 28 is sensitive to the partially covered coils and determines that bad coiling has occurred in response to detection of at least two partially covered coils (winding criteria). The control module 28 then raises the alarm and stops the winder 13 as described above.

Figures 7a - 7h illustrate another example, conceptually similar to that of

Figures 6. The control module 28 again employs edge detection to detect the edges of adjacent coils along and axially extending line 80. It will be noted that the edges of the coils of a particular layer should always be a single rope diameter D apart. An exception to this is where in one layer (e.g. layer 52) overlaps another layer (e.g. layer 50) in which case, the distance between adjacent edges at the point of overlap will be less than a single rope diameter D.

Thus, in use, an x-value of the coordinate of each edge is determined along the line 80, and is subtracted from the x-value of an adjacent coordinate, thereby to determine an axial distance between the coordinates (i.e. the width of the visible coil).

The respective distances between the adjacent coordinates are summed and divided by the total number of coordinates, thereby to determine an average distance.

The control module 28 is configured to determine how many times the spacing between adjacent coordinates differs from the average, optionally by more than a predefined tolerance (e.g. 10%). It is to be expected that the spacing between one particular pair of adjacent coordinates will differ from the average, due to a partially completed layer 52 overlapping a completed layer 50. However, the winding criteria dictate that should the spacing between two or more pairs of adjacent coordinates deviate from the average by more than the allowable tolerance, that bad coiling has occurred (as in Figures 7d - 7h). The control module 28 will then raise the alarm as described above.

The memory module 30 also includes stored thereon predefined parameters indicative of normal winding and/or of bad coiling (winding criteria) against which the control module 28 compares the audio recorded by the microphone 24. If the audio violates the predefined parameters, the control module 28 determines that bad coiling has occurred and acts as above described. The Inventor believes that the invention as exemplified is advantageous because it provides a method 100 and apparatus 21 for timeous detection of bad coiling in a winder. A human operator, who may be error-prone, is no longer required to monitor the winder constantly.

Further, once bad coiling has been detected, the winder 13 can automatically be stopped thereby to minimise damage to the winder 13 and related machine components as well as minimising the risk of human fatalities. The apparatus can be installed on existing winders and thus is retrofittable in existing mines 10.

Although the apparatus 21 and the method 100 find particular application in mines, the application is not necessarily limited thereto. For example, conventional elevator installations in buildings typically also make use of wire rope which coils around a drum or spool, and the apparatus 21 and the method 100 may be applied to such elevator installations.

Claims

1 . A method of monitoring winding of rope about a drum of a winder, the method including: sensing by means of at least one sensor at least one characteristic of the rope in a region of operative winding of the rope onto the drum during rotation of the drum; capturing the characteristic in real-time via the sensor during winding of the rope onto the drum; comparing the captured characteristic against predefined winding criteria associated with normal winding of the rope; and determining that bad coiling has occurred in response to the captured characteristic violating the winding criteria.

2. A method as claimed in claim 1 , in which sensing the at least one characteristic includes directing a plurality of sensors towards the rope.

3. A method as claimed in claim 1 or claim 2, in which the sensor is an optical sensor and capturing the characteristic includes capturing at least one image of the rope.

4. A method as claimed in claim 3, in which capturing the characteristic includes capturing a video or a series of sequential images.

5. A method as claimed in claim 3 or claim 4, in which sensing the at least one characteristic includes directing the optical sensor tangentially towards the rope.

6. A method as claimed in claim 5, which further includes determining respective radii or heights of various sections of coiled rope.

7. A method as claimed in claim 6, in which the characteristic of the rope being captured is a difference in radius between exposed layers and in which the winding criteria dictate that respective radii of innermost and outermost layers of coils may differ by no more than one rope diameter.

8. A method as claimed in claim 6 or claim 7, in which the characteristic of the rope being captured is a coordinate of an outer edge of rope of each of a plurality of axially spaced points and in which the winding criteria dictate that no more than one coordinate may differ by no more than a predefined amount from an average.

9. A method as claimed in claim 3 or claim 4, in which sensing the at least one characteristic includes directing the optical sensor inwardly toward the rope.

10. A method as claimed in claim 9, which further includes determining irregular changes in pattern of coiled sections.

1 1 . A method as claimed in claim 10, in which the characteristic being captured is a variable pattern defined by the rope during winding and in which the winding criteria dictate that a coiling pattern may change no more than once.

12. A method as claimed in claim 10, in which the characteristic being captured is a thickness of each visible coil of rope and in which the winding criteria dictate that respective thicknesses of the visible coils differ by a tolerance from an average no more than once.

13. A method as claimed in any of the previous claims, which includes providing at least one acoustic sensor proximate the drum, in which the captured characteristic is a sound of the rope as it is wound about the drum, the sound being captured by the at least one acoustic sensor.

14. A method as claimed in claim 13, in which the winding criteria include predefined acoustic waveforms.

15. A method as claimed in any of the preceding claims, which further includes raising an alarm in response to a determination of bad coiling.

16. A machine-readable medium embodying a set of instructions which, when executed by a machine, causes the machine to perform a method as claimed in any of the preceding claims.

17. An apparatus for monitoring winding of rope about a drum of a winder, the apparatus including: at least one sensor operable to capture at least one characteristic of the rope as it is wound about the drum; a memory module having stored thereon predefined winding criteria; and an electronic control module in communication with the sensor, the control module being operable to: compare the captured characteristic against the predefined winding criteria; and determine that bad coiling has occurred in response to violation by the captured characteristic of the winding criteria.

18. An apparatus as claimed in claim 17, in which the sensor includes at least one optical sensor.

19. An apparatus as claimed in claim 18, in which the control module is operable to determine respective radii or heights of various layers of coiled rope.

20. An apparatus as claimed in claim 18, in which the control module is operable to determine irregular changes in pattern of coiled layers.

21 . An apparatus as claimed in any of claims 17 to 20 inclusive, in which the sensor includes at least one acoustic sensor.

22. An apparatus as claimed in any of claims 17 to 21 inclusive, which further includes an alarm arrangement operable to raise an alarm in response to a determination of bad coiling.

23. A system which includes: a winder having a drum which is rotatable about a winding axis to wind rope about the drum; and an apparatus, as claimed in any of claims 17 to 22 inclusive, operatively associated with the winder.