Title:
Capstan assembly and control system
Kind Code:
A1


Abstract:
A method and apparatus for precisely controlling the tension of a cabling assembly is described. The control loop includes a triple-feedback-loop to allow the manufacture of a large number of cable pairs. The control loop may be used with any take-up and payoff assemblies and compensate for wide variations in take-up reel weight, cable weight, process line speeds, and pay-off tension. One of the loops of the triple-feedback-loop is under-damped and unstable and allows the control loop to compensate for the wide variations without changing control systems or cabling apparatus.



Inventors:
Sharpe, Brett E. (Ellinwood, KS, US)
Klepper, Michael A. (Hoisington, KS, US)
Application Number:
10/361058
Publication Date:
08/12/2004
Filing Date:
02/06/2003
Assignee:
SHARPE BRETT E.
KLEPPER MICHAEL A.
Primary Class:
International Classes:
H01B13/02; (IPC1-7): B65H23/18
View Patent Images:
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Primary Examiner:
LANGDON, EVAN H
Attorney, Agent or Firm:
KING & SPALDING (ATLANTA, GA, US)
Claims:

What is claimed is:



1. A cabling control system comprising: a first cabling control loop, a second cabling control loop, and a third cabling control loop.

2. The system of claim 1, where the first cabling control loop comprises an underdamped unstable control loop.

3. The system of claim 2, wherein the unstable control loop comprises a first feedback loop monitoring a take-up reel motor armature current.

4. The system of claim 3, wherein the first feedback loop compensates for variations in take-up reel weight during cabling operation.

5. The system of claim 4, wherein the first feedback loop compensates for dancer tension imbalances while processing up to about 600 pair cable configurations.

6. The system of claim 5, wherein the first feedback loop compensates for dancer tension imbalances while processing up to about 100 pair of cable configurations.

7. The system of claim 2, wherein the second cabling control loop comprises a neutrally stable control loop.

8. The system of claim 7, wherein the neutrally stable control loop is critically damped to slightly underdamped.

9. The system of claim 7, wherein the neutrally stable control loop comprises a second feedback loop and monitors take-up reel drive motor speed.

10. The system of claim 7, wherein the neutrally stable control loop comprises a second feedback loop and compensates for variations in line speed or take-up reel speed, or both, during cabling operation.

11. The system of claim 7, wherein the third cabling control loop comprises a stable control loop.

12. The system of claim 11, wherein the third stable control loop is overdamped.

13. The system of claim 12, wherein the third stable control loop comprises a third feedback loop that monitors and compensates for changes in dancer position.

14. The system of claim 11, wherein the overall loop damping ratio is approximately 0.74 across all combinations or variations in reel weight, reel fill, and line speed.

15. The system of claim 1, further comprising a capstan and dancer assembly coupled to the first, second, and third control loops.

16. The system of claim 15, further comprising a plurality of capstan and dancer assemblies coupled to the first, second, and third control loops.

17. A cabling assembly comprising: a frame; a capstan drum assembly supported by the frame; a drum drive motor coupled to the drum assembly; a dancer assembly spaced from the capstan drum assembly; a take-up reel; and a triple-loop control system for controlling cabling from the capstan drum assembly to the take-up reel.

18. The assembly of claim 17, further comprising a pneumatic cylinder for maintaining a constant tension on cables between the drum assembly and the dancer assembly.

19. The assembly of claim 18, further comprising a linear potentiometer for monitoring the position of the dancer assembly.

20. The assembly of claim 17, wherein the capstan and dancer assemblies contain up to twenty-five cable pairs.

21. The assembly of claim 20, wherein the triple-loop control system comprises a controller having an underdamped first feedback loop.

22. The assembly of claim 21, wherein the underdamped first feedback loop is programmed to monitor take-up reel motor armature current and compensate for variations in take-up reel weight.

23. The assembly of claim 21, wherein the triple-loop control system further comprises a second critically damped-to-underdamped feedback loop programmed to compensate for variations in line speed, take-up reel speed, or both, that arise as the take-up reel fills with cable.

24. The assembly of claim 23, wherein the triple-loop control system further comprises a third overdamped feedback loop programmed to compensate for variations in dancer assembly position.

25. A capstan apparatus comprising: a take-off reel assembly supported by a frame; a take-off reel drive motor coupled to the take-off reel assembly and adapted to provide a supply of wire pairs at a constant rate; a dancer assembly spaced from the take-off reel assembly and adapted to receive the supply of wire pairs at the constant rate; a pay-off reel; and a capstan controller comprising a triple-loop feedback system for controlling cabling from the take-off reel assembly to the pay-off reel.

26. The apparatus of claim 25, wherein the triple-loop feedback system comprises an underdamped first feedback loop.

27. The apparatus of claim 26, wherein the underdamped first feedback loop is programmed to monitor pay-off reel motor armature current.

28. The apparatus of claim 25, further comprising a programmable logic controller for programming and controlling the capstan controller.

29. The apparatus of claim 28, further comprising a user interface coupled to the programmable logic controller.

30. The apparatus of claim 25, further comprising one or more additional slave capstan controllers controlling one or more additional capstan apparatuses.

31. The apparatus of claim 25, further comprising a safety functions interface programmed to monitor one or more capstan apparatus parameters and shut down the capstan apparatus when the one or more parameters reach a predetermined threshold.

32. The apparatus of claim 31, wherein the one or more capstan assembly parameters comprise pay-off reel motor current, feedback signal ranges, time period between changes in feedback signals, position of the dancer assembly, and pay-off reel speed.

33. A method of controlling cabling equipment comprising applying a triple-loop feedback mechanism to a cabling controller.

34. The method of claim 33, wherein the applying the triple-loop further comprises compensating for weight variations in a take-up reel by feeding back motor armature current of a take-up reel drive motor with an underdamped first feedback loop.

35. The method of claim 34, wherein the applying a triple loop further comprises compensating for cable line speed, take-up reel speed, or both, by feeding back take-up reel motor speed with a neutrally stable second feedback loop.

36. The method of claim 35, wherein the neutrally stable second feedback loop comprises critically damping or slightly underdamping a signal indicative of the take-up reel motor speed.

37. The method of claim 35, wherein the applying a triple loop further comprises compensating for tension differences between a wire input side of a dancer and a wire output side of the dancer by feeding back dancer position with an overdamped third feedback loop.

38. The method of claim 33, further comprising providing an overall loop damping ratio of 0.74 across all combinations of variations in reel weight, reel fill, and line speed.

39. A method of controlling a cabling assembly comprising providing a triple-loop feedback mechanism.

40. The method of claim 39, further comprising conditioning a first loop of the triple-loop feedback mechanism with an underdamped transfer function.

41. The method of claim 40, wherein the first loop monitors take-up reel motor armature current and compensates for variations in take-up reel weight.

42. The method of claim 40, further comprising conditioning a second loop of the triple-loop feedback mechanism with a critically damped-to-slightly underdamped transfer function.

43. The method of claim 42, wherein the second loop monitors take-up motor speed and compensates for variations in line speed, reel speed, or both as a take-up reel fills with cable.

44. The method of claim 42, further comprising conditioning a third loop of the triple-loop feedback mechanism with an overdamped transfer function.

45. The method of claim 44, wherein the third loop monitors a dancer assembly position and compensates for differences in tension between a wire input side of the dancer and a cable output side of the dancer.

46. The method of claim 45, further comprising applying torque to a take-up reel to balance the differences in tension.

47. A method of creating a cable comprising: unreeling multiple wires to a dancer assembly at a constant rate; applying a constant tension to the multiple wires; and cabling the elements onto a take-up reel; wherein the constant tension of the elements is precisely controlled by a triple-feedback-loop.

48. The method of claim 47, wherein the triple-feedback loop comprises an underdamped first loop feeding take-up motor armature current back to a controller and compensating for variations in take-up reel weight.

49. The method of claim 48, wherein the triple-feedback loop comprises a critically damped second loop feeding take-up motor speed to the controller and compensating for variations in line speed, reel speed, or both.

50. The method of claim 49, wherein the triple-feedback loop comprises an overdamped third loop feeding dander position to the controller and compensating for differences in tension between a wire input side of the dancer assembly and a wire output side of the dancer assembly.

51. A cabling assembly comprising: a capstan drum assembly; a take-up reel; and a triple-loop control system for controlling cabling from the capstan drum assembly to the take-up reel.

52. The assembly of claim 51, further comprising a pneumatic cylinder for maintaining a constant tension on cables between the capstan drum assembly and a dancer assembly arranged between the capstan drum assembly and the take-up reel.

53. The assembly of claim 51, wherein the triple-loop control system comprises a controller having an underdamped first feedback loop.

54. The assembly of claim 53, wherein the underdamped first feedback loop is programmed to monitor take-up reel motor armature current and compensate for variations in take-up reel weight.

Description:

BACKGROUND

[0001] In today's modern environment, it is common to find communications-grade cable running by the mile through buildings, between cities, and even across oceans. Communications cables and other miscellaneous cables are found in nearly every household and building to facilitate the transfer of information, images, and other data across any distance at ever-increasing speeds.

[0002] Apparatuses for manufacturing communications and other types of cables of various kinds have been known for some time. One well-known method of cabling is the use of a capstan/dancer/pay-off reel assembly. According to a conventional capstan/dancer/pay-off reel assembly (2) shown in FIG. 1, a plurality of wire pairs (4) are wound on a capstan drum (6). The wire pairs (4) are usually unwound from the capstan drum (6) and introduced through a dancer (8). The dancer (8) is usually a movable roller or set of rollers that applies a constant tension to the wire pairs (4). The dancer (8) may also cable the wire pairs into a single cable strand (10), often in a helical configuration. The single cable strand (10) produced by the capstan (4) and dancer (8) is then usually wound onto a take-up or pay-off reel (12).

[0003] One of the most difficult tasks in producing high-quality communications cables is balancing the tension of the cable strand that is wound onto the pay-off reel with the tension added to the wire pairs by the dancer. The pay-off reel must be carefully controlled to apply a constant tension to the finished cable equal to the tension added by the dancer. However, as the finished cable is wound onto the pay-off reel, the weight of the pay-off reel changes, adding to the difficulty of maintaining balanced tension between the cable and the wire pairs. Usually no more than four wire pairs can be cabled into high-grade communication cables because of the difficulty maintaining tension balance.

[0004] This difficulty may be further explained by a simple analogy. Many vehicles include a “cruise control” feature intended to enable a driver to maintain a constant speed over long travel distances. However, the course of travel often includes hills and valleys that require the vehicle engine to compensate for the power requirements necessary to maintain a constant speed over the hills and through the valleys. Driving along relatively small hills and valleys, most vehicles can maintain the pre-selected speed within about five percent. However, on larger hills, it is common for the speeds to vary by ten to twenty percent or more because the vast changes in power demanded to maintain a constant speed.

[0005] Similarly, as cables are manufactured, the weight of the pay-off reel is constantly changing. The motor driving the pay-off reel must compensate for changes in reel weight as the cable is produced to maintain a constant tension in the produced cable in order to manufacture a cable of high quality. While a ten to twenty percent variation in speed may be adequate for most vehicles, such a significant variation in the tension of a sensitive communication cable may render the cable useless. Exacerbating the difficulty of maintaining a constant cable tension is a demand for the production of more and more wiring pairs into a single cable. The variation in pay-off reel weight from start to finish may vary by hundreds or thousands of percent.

[0006] The current approach to the problem of balancing produced-cable tension with wire pair tension is to provide an electronic loop that monitors pay-off reel motor speed. The electronic loop provides feedback to a controller, which then attempts to adjust the power to the pay-off reel motor to maintain a constant cable-line speed. However, the signals provided by the electronic loop must generally be conditioned so that they remain stable. The conditioned signals are thus damped and result in a limited control range. Typical single-control loops do not provide the capability of manufacturing cables from high numbers of wire pairs while maintaining a tension balance between the wire input side of the dancer and the cable output side of the dancer. Therefore, according to the current state of the art, very few pairs (usually four or less) of wires can be effectively cabled in to high-grade communications cables.

[0007] Further, typical cabling machinery and controls are designed for specific product types, processed under conditions unique to the particular product type. For those who manufacture multiple product types, multiple sets of machinery-each dedicated to a particular product-are required. Alternatively, in some instances a single set of machinery is used for multiple product types, but significant modifications and/or extensive machine set-ups must be done each time a product is changed.

SUMMARY OF THE INVENTION

[0008] In one of many possible aspects, the present invention provides a cabling control system including a first cabling control loop, a second cabling control loop, and a third cabling control loop. The first cabling control loop may be under-damped and unstable.

[0009] Another aspect of the present invention provides a cabling assembly including: a frame, a capstan drum assembly supported by the frame, a drum drive motor coupled to the drum assembly, a dancer assembly spaced from the capstan drum assembly, a take-up reel, and a triple-loop control system for controlling cabling from the capstan drum assembly to the take-up reel.

[0010] Another aspect of the present invention provides a capstan apparatus including: a take-off reel assembly supported by a frame, a take-off reel drive motor coupled to the take-off reel assembly and adapted to provide a supply of wire pairs at a constant rate, a dancer assembly spaced from the take-off reel assembly and adapted to receive the supply of wire pairs at the constant rate, a pay-off reel, and a capstan controller including a triple-loop feedback system for controlling cabling from the take-off reel assembly to the pay-off reel.

[0011] Another aspect of the present invention provides a method of controlling cabling equipment including applying a triple-loop feedback mechanism to a cabling controller.

[0012] Another aspect of the present invention provides a method of controlling a cabling assembly including providing a triple-loop feedback mechanism.

[0013] Another aspect of the present invention provides a method of creating a cable including unreeling multiple wires to a dancer assembly at a constant rate, applying a constant tension to the multiple wires, and cabling the elements onto a take-up reel, wherein the constant tension of the elements is precisely controlled by a triple-feedback-loop.

BRIEF DESCRIPTION OF THE DRAWINGS

[0014] The accompanying drawings illustrate various aspects of the present invention and are a part of the specification. Together with the following description, the drawings demonstrate and explain the principles of the present invention. The illustrated aspects are examples of the present invention and do not limit the scope of the invention.

[0015] FIG. 1 is a diagram of a conventional cabling assembly.

[0016] FIG. 2 is a front view of a capstan assembly according to one aspect of the present invention.

[0017] FIG. 3 is a side view of the capstan assembly of FIG. 2 according to one aspect of the present invention.

[0018] FIG. 4 is a diagrammatical representation of a cabling and control system according to one aspect of the present invention.

[0019] FIG. 5 is diagrammatical representation of the control loop of a cabling system according to one aspect of the present invention.

[0020] Throughout the drawings, identical reference numbers designate similar, but not necessarily identical, elements. While the invention is susceptible to various modifications and alternative forms, specific aspects have been shown by way of example in the drawings and will be described in detail herein. However, it should be understood that the invention is not intended to be limited to the particular forms disclosed. Rather, the invention is to cover all modification, equivalents and alternatives falling within the scope of the invention as defined by the appended claims.

DETAILED DESCRIPTION OF ASPECTS OF THE INVENTION

[0021] Turning now to the figures, and in particular to FIGS. 2-3, a front and side view of a cabling assembly (20) according to one aspect of the present invention is shown. The cabling assembly (20) of the present aspect includes a frame such as the metal support frame (22) shown. Mounted to the support frame (22) is a capstan drum assembly (24). The capstan drum assembly (24) may have any number of wire pairs wound thereon for producing a cable. For example, in some aspects the capstan drum assembly (24) has as few as two wire pairs, in others it may have as many as twenty-five pairs or more.

[0022] The capstan drum assembly (24) is coupled to a capstan drum drive motor (26) that provides rotational power to the capstan drum assembly (24). The capstan drum assembly (24) and the capstan drum drive motor (26) are commercially available from a variety of sources.

[0023] The capstan drum drive motor (26) is controlled to provide the wire pairs from the capstan drum assembly (24) to a dancer assembly (28) at a constant rate. The power provided by the capstan drum drive motor (26) may vary as the wire pairs are unwound from the capstan drum assembly (22) and the weight of the capstan drum assembly (22) decreases.

[0024] The dancer assembly (28) is supported by the support frame (22) and spaced from the capstan drum assembly (22) according to the present aspect. Alternatively, the dancer assembly (28) may include a separate support frame. The dancer assembly (28) includes a roller (30) slidingly mounted along first and second guides (32 and 34). The roller (30) may therefore travel linearly along the guides (32 and 34), as well a rotate about a shaft (36). The dancer assembly (28) provides a constant tension to the wiring pairs that extend from the capstan drum (24) and around the roller (30). The constant tension is facilitated by a cylinder mounted between the roller (30) and the support frame (22). The cylinder of the present aspect is a pneumatic cylinder (38) that provides a constant force to the roller (30). The constant force causes the roller (30) to move along the guides (32 and 34) to keep the tension in the wire pairs extending from the capstan drum assembly (24) substantially constant.

[0025] Air or other gas for the pneumatic cylinder (38) may be supplied at a constant pressure by a supply cylinder (40) mounted to the support frame (22). In addition, an air assembly (42) may be mounted to the support frame (22) to provide air to the supply cylinder (40) at a constant pressure and may include a gauge (44) and filter (46).

[0026] A position sensor, which monitors and reports position, is also mounted between the dancer assembly (28) and the support frame (22). According to the present aspect of the invention, the position sensor is a linear potentiometer (48). The linear potentiometer (48) is commercially available from many sources and provides for accurate measurement of the position of the dancer assembly (28).

[0027] As mentioned above, the cabling assembly (20) of the present aspect may include many wiring pairs to generate a communication cable. In some aspects, the cabling assembly (20) may hold up to twelve wiring pairs. In other aspects the cabling assembly (20) may include up to twenty-five wiring pairs or more. In addition, multiple cabling assemblies (20) may be linked together in series to create cables with any number of strands. For example, four cabling assemblies (20) of twenty-five wiring pairs each may be arranged in series to produce a one-hundred strand cable. Ever more cabling assemblies (20) may be arranged in series or parallel to create cables of six-hundred strands or more. However, the cabling assemblies (20) need not be the same, or hold the same number of wiring pairs.

[0028] While the control of the cabling assembly (20) to facilitate precise tension control for high numbers of wiring pairs has not been possible in the past, a control system according to one aspect of the present invention enables precise control of multiple cabling assemblies (20) with high numbers (twelve or more) of wire pairs. Of course the control system described above may also be used to control low numbers of wire pairs.

[0029] Turning next to FIG. 4, a representation of a cabling control system (100) according to one aspect of the present invention is shown. The cabling control system (100) is shown coupled to a capstan, for example the cabling assembly (20) described above. The cabling assembly (20) may be a first or master capstan apparatus as shown in FIG. 4. The details of the master capstan apparatus are discussed above with reference to FIGS. 2 and 3. An optional second capstan, for example a slave capstan apparatus (120), is also shown coupled to the cabling control system (100) according to the aspect of FIG. 4. The slave capstan apparatus (120) may be similar or identical to the master cabling apparatus (20), but this is not necessarily so. The slave capstan apparatus (120) and master cabling apparatus (20) may differ in structure in some aspects. Further, in some aspects, the slave capstan apparatus (120) is omitted altogether, and in other aspects, the slave capstan apparatus (120) is representative of a plurality of many slave capstans, each controlled by the cabling control system (100). The number of capstans may vary from a single master cabling apparatus (20) to dozens of capstans or more.

[0030] The master cabling apparatus (20) is electrically connected via an interface (106) to a master capstan controller (108). The master capstan controller (108) may include a commercially available programmable motor controller, such as a programmable DC (direct current) motor controller. Similarly, as shown in the aspect of FIG. 4, the slave capstan apparatus (120) (if any) may include a communication interface (112) to a slave capstan controller (110). The slave capstan controller (110) may include a commercially available programmable motor controller similar or identical the master capstan controller (108). In aspects with more than one slave capstan (104), each slave capstan may include a slave capstan controller (110) or they may all be controlled by the master capstan controller (108).

[0031] A plurality of wire pairs (114 and 116) from the master cabling apparatus (20) and the slave capstan apparatus (120) may be cabled and introduced to a take-up reel (118). The take-up reel (118) includes a communication interface (121) to a take-up controller and motor (122) according to one aspect of the present invention. The take-up controller and motor (122), the master capstan controller (108), and the slave capstan controller (110) are each in communication with a programmable logic controller (“PLC”) (124). The take-up controller and motor (122) is programmed and controlled by the PLC (124) via a communication interface (126). Similarly, the master and slave capstan controllers (108 and 110) are also programmed and controlled by the PLC (124) via two additional communications interfaces (128 and 130). The PLC (124) is commercially available from a variety of sources.

[0032] The PLC (124) may be communicably connected via an interface (132) to a human machine interface (134). As with the PLC (124), the human machine interface (134) is commercially available from a variety of sources. The human machine interface (134) facilitates programming of the PLC (124) by a user and may include a keyboard, mouse, display, touch-screen, and/or other human machine interfaces.

[0033] In some aspects, the PLC (124) may also be operatively connected to a safety function interface (136). The safety functions interface (136) may be used to monitor characteristics of the cabling/capstan apparatus (e.g. 20 and 120) and/or the take-up reel (118) and cause the PLC to shut the capstans (20 and 120) and take-up reel (118) down when certain parameters are met. For example, the safety function interface (136) may monitor motor current of the take-up reel (118) and/or the capstan drum drive motor (26, FIG. 2) of the capstan assemblies (20 and 120). The safety function interface (136) may also monitor feedback signals to ensure that they are within realistic ranges. Further, the safety function interface (136) may monitor the feedback signals to ensure that they change regularly (an extended period without any changes may indicate a problem). The safety function interface may also monitor production speed, take-up reel speed, and/or capstan drum (24) speeds to ensure that the cabling operation is functioning within acceptable limits. The safety function interface (136) may also monitor the cabling assemblies (20 and 120) and their components, as well as the take-up reel, for possible misplacements. The monitoring for misplacements may be facilitated by one or more photo eyes operatively connected to the safety function interface (136). The safety function interface (136) may also include any other monitors as desired to check for anything abnormal in the cabling process and shut the system (100) down in the event that any monitored parameter exceeds (or falls under) a predetermined threshold programmed into the safety function interface (136) or the PLC (124).

[0034] The cabling control system (100) may include a plurality of control loops to facilitate the production of a cable (138). According to the aspect of FIG. 4, the cabling control system (100) is a triple-loop configuration. The triple-loop control system shown primarily controls the tension of wires being cabled, which in turn determines the quality of the cable produced. The more closely balanced the tension on each side of the dancer assemblies (28/128) is, the better the quality of the cable. However, as discussed above, it may be extremely difficult or impossible with conventional cabling control systems to balance the tension between the dancer assemblies (28/128) and the take-up reel (118) with the tension applied by the dancer assemblies (28/128) to the wires pairs being cabled from the capstan drum (24/124). The tension of the cable (138) downstream of the dancer assemblies (28/128) is a function of the take-up reel (118) rotation. And as the take-up reel (118) fills with cable (138), it comes more and more difficult to maintain a constant take-up reel (118) speed or constant cable (138) line speed—especially for cables made of a dozen or more wire pairs. A high number of wire pairs (e.g. a dozen or more) creates a wide variation in weight between an empty pay-off reel and a full pay-off reel.

[0035] Therefore, in order to facilitate cabling of high numbers of wire pairs, a triple-loop control configuration is used. A triple-loop control configuration (200) according to one aspect of the present invention is shown in FIG. 5. The triple-loop control loop configuration (200) as shown may be programmed into the PLC (124, FIG. 4) by those of skill in the art having the benefit of this disclosure. The triple-loop control configuration (200) includes three distinct control loops.

[0036] A first control loop is an underdamped feedback loop (202). Because the first control loop is underdamped, it tends to be unstable, but highly sensitive to changes. According to the present aspect, the under-damped feedback loop (202) monitors and compensates for variations in take-up reel (118) weight. The under-damped feedback loops (202) feeds back to the PLC (124, FIG. 2) armature current of a take up reel drive motor (204). As the cable (138) is manufactured, it winds up on the take-up reel (118). The take-up reel (118) therefore increases in weight as the cable (138) is produced. Accordingly, the take-up reel drive motor (204) must continuously adjust to provide a constant tension to the cable (138) as it traverses the dancer (28) of the cabling assembly (20). The tension in the cable (138) must be quite precise for communications cables and other sensitive cables to ensure the quality of the cable (138). In some aspects, the cable (138) may be made from up to twelve pairs of wires, up to twenty-five pairs of wires, up to one-hundred pairs of wires, up to about six-hundred pairs of wires, or even more. For example a set of four cabling assemblies (20, 120, etc.), each having twenty-five wire pairs of may be operatively connected to one another and controlled by the triple-loop control system (200) to create a one-hundred strand cable.

[0037] Therefore, the challenge of compensating for weight variations in a cable with many pairs of wires is considerable prior to the present invention. Accordingly, present invention uses the triple-loop feedback control system (200) to enable precise control of wide ranges of cable sizes and wide ranges in the number of wiring pairs being cabled.

[0038] As will be understood by those of skill in the art having the benefit of this disclosure, the introduction of the first under-damped feedback loop (202) can advantageously adjust quickly to wide variations in take-up reel (118) weight as a cable of many strands is produced. The first under-damped feedback loop (202) may also be used to monitor and adjust for other cabling components. A transfer function (208) is applied to the first under-damped feedback loop (202) to condition the signal indicating armature current drawn by the take-up reel drive motor (204). The transfer function according to one aspect of the present invention is: 1KA(1+s τA1)(1+s τA2)(1)embedded image

[0039] where, according to standard notation:

[0040] KA is a physical constant that does not change and is representative of the cabling equipment;

[0041] s is a LaPlace transform; and

[0042] τA1 and τA2 are changing constants based on changes in the take-up reel (118) weight.

[0043] It is readily apparent to those of skill in the art having the benefit of this disclosure that equation (1) represents an under-damped transfer function, and therefore provides an unstable feedback loop that would not be used according to conventional control practice because of the potential for loss of control of the control loop (200). It is also apparent to those of skill in the art having the benefit of this disclosure that other under-damped transfer functions may be applied to the first feedback loop (202) to increase the range of accurate controls on high numbers of wire pairs being cabled, and that equation (1) is exemplary in nature. That is, the present invention is not limited to the transfer function of equation (1).

[0044] The first under-damped feedback loop (202) may compensate for take-up reel (118) weight variations for up to about six hundred pair cable configurations or even more. By compensating for take-up reel (118) weight variations, the first under-damped feedback loop (202) adjusts for tension imbalances between the wire pairs (114) and the manufactured cable (138) and causes a torque to be applied to the take-up reel (118) as necessary to balance the tensions. According to the triple-loop control system (200) of the present invention, there is no theoretical limit to the number of wire pairs that can be effectively cabled. However, because the first feedback loop (202) is unstable, according to one aspect of the present invention, there are two additional feedback loops facilitating tension balance of the wires (114) and the cable (138) before and after the dancer assembly (28). The additional feedback loops ensure control of the cabling equipment (Capstan assemblies (20 and 120), dancer (28) take-up reel (118), etc.) without compromising the added benefit of the first unstable feedback loop (202) to facilitate precise control over a high number of wire pairs being cabled.

[0045] A second control loop of the two additional feedback loops is a neutrally stable feedback loop (208). According to the aspect shown, the second neutrally stable feedback loop (208) monitors and compensates for variations in cable (138) line speed and/or reel (118) speed during cabling operation. However, the second neutrally stable feedback loop (208) may also monitor and compensate for other cabling operation parameters.

[0046] As discussed above, because of the increasing weight on the pay-off reel (118) during cabling operation, the line speed and/or reel speed tends to change without feedback-control of the take-up reel drive motor (204). The neutrally stable feedback loop (208) feeds back to the PLC (124, FIG. 2) actual motor speed of the take-up reel drive motor (204), the take-up reel (118) speed, and/or the cable line speed. As tension imbalances are detected and fed-back, a measured torque may be applied to the pay-off reel (118) to balance the tensions.

[0047] As also discussed above, when the cable (138) is manufactured, it winds up around the take-up reel (118). The take-up reel therefore increases in weight as the cable (138) is produced. Accordingly, a take-up reel drive motor (204) must continuously adjust to provide a constant speed to the take-up reel in order to impart a constant tension to the cable (138) as it traverses a dancer (28) of the cabling assembly (20). While the second neutrally stable feedback loop (208) is not as sensitive to changes in cable (138) tension by monitoring take-up motor drive (204) speed, take-up reel speed, and/or cable (138) line speed as the first unstable feedback loop (202), it provides a stable additional input to the first unstable feedback loop (202) to prevent the cable production process from going out of control (as may happen otherwise with feedback from only the unstable feedback loop (202)). In addition, the actual take-up motor speed, take-up reel speed, and/or line speed is typically a good indicator of cable (138) tension, and therefore feeding back the speed of the motor, reel, and/or line to the PLC (124, FIG. 4) adds to the precision of the control system (200).

[0048] A second transfer function (228) is applied to the second neutrally stable feedback loop (208) to condition the signal reported by the second feedback loop (208) indicative of cable line speed, take-up drive motor speed, and/or reel speed. The transfer function according to one aspect of the present invention is: 2KV(1+s τV1)(1+s τV2)(2)embedded image

[0049] where, according to standard notation:

[0050] KV is a physical constant that does not change and is representative of the cabling equipment;

[0051] s is a LaPlace transform; and

[0052] τV1 and τV2 are changing constants based on changes in the weight of the take-up reel (118).

[0053] It is readily apparent to those of skill in the art having the benefit of this disclosure that equation (2) represents a critically damped to slightly under-damped transfer function, and therefore provides the neutrally stable second feedback loop (208). It is also apparent to those of skill in the art having the benefit of this disclosure that other neutrally stable transfer functions may also be applied to the second feedback loop (208), and that equation (2) is exemplary in nature. That is, the present invention is not limited to the transfer function of equation (2) but may use any function causing critical-to-slightly under-damping.

[0054] A third control loop of the two additional feedback loops is an unconditionally stable loop (230) according to some aspects of the invention. The third stable feedback loop (230) monitors and compensates for variations in dancer assembly (28) position. As the tension on the pay-off reel (118) side of the dancer assembly (28) tends to fluctuate with the increasing weight of the pay-off reel (118), the position of the dancer assembly (28) changes to maintain a constant tension on the wire pairs (114) coming from the take-off reel (24). Therefore, changes in position of the dancer assembly (28) may indicate a tension imbalance across the dancer assembly (28).

[0055] Accordingly, the third stable feedback loop (230) feeds back to the PLC (124, FIG. 2) the dancer assembly (28) position according to the present aspect. The third stable feedback loop (230) may feedback other aspects of the cabling equipment including, but not limited to those mentioned with reference to the first two feed back loops. The information from the third stable feedback loop (230) may be taken into account to adjust the control of the take-up reel drive motor (204) to provide a constant tension to the cable (138) on the pay-off reel (118) side of the dancer assembly (28) by applying a certain torque to the pay-off reel (118) by the take-up reel drive motor (204). While the third stable feedback loop (230) is not as sensitive to changes in cable (138) tension by monitoring dancer position as the first unstable feedback loop (202), it provides another stable input to the first and second feedback loops (202 and 208). The additional feedback loop (230) may prevent the cable production process from going out of control and allow for more precise tension control of the produced cable (138). The additional precision comes as the additional input on the dancer (28) position is compensated for. However, because the second neutrally stable feedback loop (208) and the third stable feedback loop (230) are damped significantly more than the first unstable feedback loop (202), neither the second or third feedback loops—alone or in combination—can provide the range and flexibility of the triple-loop configurations including the first feedback loop (202).

[0056] A third transfer function (232) is applied to the third stable feedback loop (230) to condition the signal reported by the third feedback loop (230) indicative of dancer assembly (28) position. The transfer function according to one aspect of the present invention is: 3KP(s τP1)(1+s τP2)(3)embedded image

[0057] where, according to standard notation:

[0058] KP is a physical constant that does not change and is representative of the cabling equipment;

[0059] s is a LaPlace transform; and

[0060] τP1 and τP2 are changing constants based on the weight of the take-up reel (118).

[0061] It is readily apparent to those of skill in the art having the benefit of this disclosure that equation (3) represents an overdamped transfer function, and therefore provides the unconditionally stable third feedback loop (230). It is also apparent to those of skill in the art having the benefit of this disclosure that other stable transfer functions may also be applied to the third feedback loop (230), and that equation (3) is exemplary in nature. That is, the present invention is not limited to the transfer function of equation (3).

[0062] According to the present aspect of the triple-loop control system (200), the overall loop damping ratio is about 0.74 across all combinations of variations in reel weight, reel fill, and line speed. The triple-loop control system (200) may advantageously be used for any cabling equipment, and is not limited to the cabling assembly (20) described above. The triple-loop feedback system compensates for wide variations in take-up reel (118) weight, cable weight, process line speeds, and pay-off tension automatically. Thus a single set of machines (such as cabling assembly (20)) may be used to process a multitude of products at varying speeds.

[0063] In addition, the control system of the present invention is not limited to only three control loops. Additional control loops may also be added to further enhance the control of the cabling assembly (20). There may be four or more control loops according to some aspects of the invention. Additional control loops may, for example, monitor and report “jerk” (rapid acceleration changes).

[0064] The preceding description has been presented only to illustrate and describe aspects of invention. It is not intended to be exhaustive or to limit the invention to any precise form disclosed. Many modifications and variations are possible in light of the above teaching.

[0065] The foregoing aspects were chosen and described in order to illustrate principles of the invention and some practical applications. The preceding description enables others skilled in the art to utilize the invention in various aspects and with various modifications as are suited to the particular use contemplated. It is intended that the scope of the invention be defined by the following claims.





 
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