Abstract:
Mechanisms and designs of large scale, modular, robotic software-defined patch-panels incorporate numerous features that ensure reliable operation. A telescopic arm assembly ( 104 ) with actuated gripper mechanism ( 103 ) is used to transport internally latching connectors ( 101 ) within a stacked array of translatable rows ( 102 ). A unique two-state magnetic latching feature provides reliable, low loss optical connections. Flexible, magnetically levitated internal structures are provided to assist the robot in automatically aligning to, engaging, and disengaging any internal connection in a fast reliable process within the stacked array.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The present invention is directed in general to large scale robotic cross-connect systems providing low loss, software-defined fiber optic connections between a large number of pairs of ports. Mechanisms in the systems incorporate numerous features that ensure reliable operation. 
         [0003]    2. Description of the Background Art 
         [0004]    Large scale automated fiber optic cross-connect switches and software-defined patch-panels enable data centers and data networks to be fully automated, wherein the physical network topologies are software-defined or programmable, for improved efficiencies and cost savings. Current fiber optic switch technologies such as cross-bar switches scale as N 2  (N is the number of ports) making them ill-suited for large scale production networks. Prior art disclosures of cross-bar switches include U.S. Pat. No. 4,955,686 to Buhrer et al, U.S. Pat. No. 5,050,955 to Sjolinder, U.S. Pat. No. 6,859,575 to Arol et al, and U.S. Patent No. 2011/0116739A1 to Safrani et al. 
         [0005]    More recent automated patch-panel approaches that scale as linearly with the number of ports utilize braided fiber optic strands. Advances in the mathematics of topology and Knot and Braid Theory (U.S. Pat. Nos. 8,068,715, 8,463,091, 8,488,938 and 8,805,155 to Kewitsch) have solved the fiber entanglement challenge for dense collections of interconnect strands undergoing arbitrary and unlimited reconfigurations. Since this Knots, Braids and Strands (KBS) technology scales linearly in the number of interconnect strands, significant benefits over cross-bar switches such as density and hardware simplicity are realized. Existing systems featuring autonomous patch panel systems and implementing KBS algorithms in accordance with the Kewitsch patents referenced above typically utilize a pick and place robotic actuation system with a gripper at the end of the robotic arm to grab and transport a fiber optic connector and the fiber optic strand extending therefrom to a central backbone in the system. The robotic arm is of a narrow width and extended depth to allow it to descend into the dense fiber optic interconnect volume with no mechanical interference and no contact with surrounding fibers, yet still having sufficient rigidity to experience minimal deflection under transverse forces including magnetic repulsion and tension originating from the fiber being carried in the gripper therein. However, further improvements in this new class of physical fiber optic switching or connection management system are always desirable, including those relating to improvements in compactness, hardware simplicity and operative reliability, singly or in combination. 
       SUMMARY OF THE INVENTION 
       [0006]    The present invention relates to apparatus to improve the performance of this new type of cross-connect utilizing braided fiber optic strands and the application of the mathematics of topology to this scaling challenge. In this invention, a highly reliable automated cross-connect system is employed with multiple unique hardware and operative features to provide superior compactness, performance and reliability. For example, a dense three-dimensional matrix of parallel and precisely separated connector elements is distributed through two orthogonal dimensions, with a plurality of multi-functional elements being disposed along each connection path in the third dimension. The connector paths each comprise individual ones of a plurality of linear base elements which are each separately movable to align with a chosen base element in the cross-connect system. The invention includes unique magnetically latched fiber optic connector devices which enable the system to provide multiple different user defined states of insertion loss. The devices include reliable, self-guiding, attraction mode magnetic latching to facilitate repeatable robotic engagement and reconfiguration. Robotic miniature gripper devices that retain the magnetically latched fiber optic connectors are further disclosed, wherein the miniature gripper includes integral sensing and actuation means to ensure proper engagement with a selected connector. Furthermore, the system is configured with movable rows of multiple, spaced apart horizontal connector receptacles, stacked vertically therein. Each row is comprised of multiple parallel connector tracks, and each connector track includes a mating connector receptacle, a fiber optic interface port, and combined mechanical and magnetic reference features which are configured to achieve reliable latching and locating of both the fiber optic connector device and the gripper device. The movable rows of connector receptacles incorporate precision injection molded translation assemblies and actuation means to accurately and precisely translate rows between one of three horizontal locations. These locations generate the vertical row shuffling response as dictated by the KBS algorithm and aid in improving the volumetric efficiency of the system. 
         [0007]    The gripper consists of a two-part body, a central body which mechanically engages or interlocks with a particular target connector extended member in between the multiplicity of surrounding extended members, and a driven, translatable outer body or frame incorporating means to engage and sense the reconfigurable internal fiber optic connector assembly. The narrow width gripper, attached to the lower end of the controlled telescopic arm, descends down onto a selected centered connector row until a gripper interlock sensor detects proper engagement with the extended member. The gripper outer body translates parallel to the extended member to plug-in, unplug or partially disconnect the internal connector assembly. The translation mechanism uniquely incorporates a drive line, wrapped around a motor drive shaft with a small but precise excess length to control bidirection lateral translation of the gripper. This obviates the stalling of the drive motor upon a startup acceleration from a state of rest. 
         [0008]    The cross-connect system is also based on a three-dimensional array of parallel but precisely laterally separated elongated reference members disposed in an augmentable vertical stack of horizontal rows. The reference members are narrow and of selected uniform length having chosen flexure properties, and include sets of small permanent magnets deployed so as to utilize both magnetic attraction and repulsion forces during different and separate operative states of engagement. Each narrow reference member is positioned to be closely adjacent to a different receiving aperture into which the end of a different optical fiber connector can be inserted. The end apertures lie in transversely disposed horizontal rows in a vertical connection plane and each is positioned to potentially receive the end of the optical fiber connector repositioned by the system. The small permanent magnets along their lengths are positioned selectively and with such polarities as to provide at least two stable insertion positions and also a transversely repulsive force, to maintain adjacent elements separate in a dense three-dimensional array of elements. 
         [0009]    This application further discloses a uniquely compact configuration for accessing and repositioning optical fibers on command. Telescopic robotic arm devices of minimal transverse compliance and high length efficiency (ratio of the range L 2  to retracted height L 1 ), independent of extended length (zero to L 2 ) are achieved by deployment of a unique vertical telescoping structure that is horizontally movable from one connector track, through surrounding fibers and to another connector track under the direction of the KBS algorithm. The two-stage telescopic arm arrangement is based on chosen linear lengths of a vertical rectangular tube or “C” shaped outer body, with an internal slider body maintained in alignment by a unique sliding bearing carriage and spring preloading arrangement within the telescopic arm. The arrangement enables a constant length, flat, flexible electrical interface cable to be routed dynamically from the gripper mechanism to an external control system, which serves the dual purpose of pulling the internal sliding body so it moves in synchronism with the outer body. The robotic arm and gripper configuration is of very narrow width, enabling it to move unencumbered throughout the limited spaces in the fiber interconnect volume. 
         [0010]    An automated cleaning device is further described, with the additional feature of integral sensing of the force on the cleaning fabric and polished fiber optic connector ferrule during cleaning. The electrical signal produced therein is utilized to provide feedback to accurately control the robot position and maintain less than a maximum value of compressive force at the fiber end face. This precise control ensures repeatable, high quality cleaning of the fiber end face, preventing the accumulation of particulates to thereby achieve consistently low insertion loss, high return loss optical connectivity, for superior quality and consistency compared to present manual processes. In the fiber cleaning subsystem, the cleaning fabric is fed from a supply spool through the cleaning cassette pad and onto a dispense spool. The arrangement enables multiple fibers to be cleaned from a single supply spool. 
         [0011]    Stacked planar arrays of optical fiber take-up spools with fibers dynamically routed through a combination of eyelets, guides and rollers distributed in a precisely spaced geometry provide a source of low loss optical fiber connections between a fixed input array and a physically changeable output array. Each spool is independently tensioned to the degree necessary to retract any excess length of fiber between the internal one-dimensional backbone and two-dimensional output connector array, without subjecting the fiber to excessively sharp bends resulting from the controlled tension, such that the reliability and optical transmission characteristics of the fiber are not compromised. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0012]      FIG. 1A  depicts the arrangement of a number of significant functional elements comprising a robotic fiber optic cross-connect system in accordance with the present invention, populated with one set of eight rows and with capacity for adding more rows both below and above those eight rows as depicted;  FIG. 1B  is a block diagram of other inventive combinations in accordance with the invention;  FIG. 1C  is a simplified perspective view illustrating the arrangement of interrelated modules, and  FIG. 1D  is a block diagram of some interrelated system elements in accordance with this invention; 
           [0013]      FIG. 2  depicts a fragmentary view of the magnetically latching internal fiber optic connector in accordance with the invention, including its features for interfacing and mating within the robotic gripper, its relationship to a connector row for receiving and holding the connector, and a side detailed view of the resulting magnetic repulsion forces between connector rows; 
           [0014]      FIG. 3  is an interior view of a stacked arrangement of eight connector rows, forming a stackable module of 96 fiber optic ports with means to magnetically engage fiber optic connectors transported thereto by the gripper, further illustrating the relationship between the connector magnet and the connector row magnets with a tri-state configuration; 
           [0015]      FIG. 4  illustrates an exterior view of the same stacked arrangement of eight connector rows, producing the two dimensional array of fiber optic ports to which external cables requiring cross-connections are plugged in; 
           [0016]      FIG. 5  is a side view of a gripper device in accordance with the invention, with fiber optic connector in the allocate configuration detailing the numerous positional sensing and actuation means; 
           [0017]      FIG. 6  is a side view of the gripper device in the unallocated configuration; 
           [0018]      FIG. 7  is a side view of the gripper device in the unplug configuration; 
           [0019]      FIG. 8A  is a partial, perspective view of a two-axis robotic actuation system in accordance with the invention, which moves a gripper mechanism within the internal fiber cross-connect volume;  FIG. 8B  is a schematic view of an x axis drive mechanism;  FIG. 8C  is a schematic view of a y axis drive mechanism;  FIG. 8D  is a schematic view of the y axis drive in various extended states;  FIG. 8E  illustrates the gripper z axis drive mechanism in central position,  FIG. 8F  in left position,  FIG. 8G  in right position, and  FIG. 8H  illustrates the velocity trajectory of the gripper stepper motor actuating the z axis drive; 
           [0020]      FIG. 9  is a further perspective and diagrammatic view of actuation system of  FIGS. 8A-8C , depicting the gripper at the end of a two-stage telescopic arm in the fully extended state; 
           [0021]      FIG. 10A  is a partial view of the two-stage telescopic arm in the partially extended state,  FIG. 10B  is a partial breakaway view of the vertical portion of a telescopic arm in the substantially retracted range of travel, and  FIG. 10C  is a perspective view, also partially broken away, of different segments of the telescopic arm in the substantially extended range of travel; 
           [0022]      FIGS. 11A and 11B  are top perspective views of an improved fiber take-up tray for fiber tensioning and dynamic slack fiber management, each including twelve individual reels and fiber guides facilitating low loss, dynamic optical fiber routing therebetween to the central backbone, depicting the portion of fibers in front of the backbone in  FIG. 11A  and the portion of the fibers in back of the backbone in  FIG. 11B ; 
           [0023]      FIG. 12  is a perspective view of a portion of the stacked arrangement of multiple fiber take-up trays, detailing the routing of optical fibers from individual reels to the central backbone through low friction o-ring shaped eyelets and soft rubber-clad rollers; 
           [0024]      FIG. 13A  is a partial cutaway perspective view of a portion of the optical fiber reel system including sensing electronics to detect the rotation of the reel during dynamic reconfiguration such that proper fiber slack management can be validated,  FIG. 13B  is a block diagram of a subsystem for processing the electronic signals from the sensing electronics to establish proper system response to reel position commands; 
           [0025]      FIG. 14  is a first partial cutaway perspective view detailing a part of a gripper device and the cleaning cartridge, and in accordance with the invention, showing a force sensor integral to a fiber end face cleaning device in operative position; 
           [0026]      FIG. 15  is a second partial cutaway view of the operative side of the fiber end face cleaning device of  FIG. 14  in operative position relative to the gripper device; and 
           [0027]      FIGS. 16A and 16B  are partial cutaway bottom and top views respectively, of the fiber end face cleaning device, as depicted generally in perspective views of the system such as  FIGS. 1, 9 and 10A , and showing a number of advantageous operative features therein. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     I. Robotic Cross-Connect System 
       [0028]    This application discloses robotic cross-connect systems providing low loss, software-defined fiber optic connections between a large number of pairs of ports. The number of ports typically ranges from 48×48 up to 1008×1008 and beyond.  FIGS. 1A-1D  illustrate a number of principal aspects of this system, comprised of a robot module  112  including a telescopic robot arm assembly  104 , a fiber optic connector end face cleaning module  105 , a miniature actuated gripper  103 , a stacked arrangement of connector rows  102 - 1  . . .  102 -N, and a stacked arrangement of fiber take-up reel trays  106 - 1  . . .  106 -N. Groups of connector rows  102 - 1  . . .  102 - 8  further comprise the front actuated patch-panel of fiber module  113 . The gripper  103  is able to unplug any fiber connector  101 - n  from among the array of fiber connectors inserted along the connector rows  102 , then transport it in a deterministic, optimal weaving pattern between the surrounding fiber connectors of the array upon manipulation by the robot arm assembly  104 . The process of transport thus includes a coordinated, sequential, multi-step movement of the robot and programmatic shuffling of each connector row  102  in accordance with the KBS algorithm as described in U.S. Pat. No. 8,463,091 referenced above. Before plugging in the fiber connector  101 - n  to its chosen final port  55 , the polished fiber end face of fiber connector  101 - n  may be cleaned by the fiber end face cleaning module  105  as shown generally in  FIGS. 1 and 9  and described in detail below with respect to  FIGS. 14 to 16B . The fiber connector  101 - n  terminates the internal optical fiber  52 , wherein this optical fiber originates from an automatic, spring loaded take-up reel residing within the multiple take-up reel tray  106 . The take-up reels ensure that all internal optical fibers are maintained under slight tension in the fiber interconnect volume between the connectors  101  and the take-up reels so that they follow substantially straight-line paths for all possible arrangements of connectors  101  within ports  55 . Straight-line paths are efficiently represented mathematically and facilitate the routing by the KBS algorithm as described in the above referenced patents. 
         [0029]    In reference to the block diagram in  FIG. 1B  and the perspective views in  FIGS. 1C-1D , the KBS algorithm is implemented in software instructions residing on server  109  and communicating in parallel with each Fiber Module  113 - 1  . . .  113 - 10 , Docking Module  114 , Optical Power Monitor Module  115 , Robot Module  112 , and Power Management Module  111  through the Ethernet Switch  110  and by use of the Ethernet protocol TCP/IP. In a further example, each module is powered by 24 VDC, which is supplied by a power distribution bus in the Power Management Module  111 . The Robot Module  112  is in communication with a Gripper Sensor Circuit  116  to detect the operative state of the fiber connector in transport, as well as a comparator circuit for a force sensor  56  (e.g. a thin film resistive sensor) integral to the cleaning cartridge. The fiber modules  113  each are in communication with a multiplexed array of reel encoder sensors responsive to the rotation of any particular take up spool  41 , the rotation resulting from internal fiber length changes due to movement of the internal fiber connector. 
         [0030]      FIGS. 1A, 1B, 1C  further depict details of the integrated and cooperative relationship between several novel operative parts of this system, which further extend the art of automatic switching of selected ones of a plurality of optical fiber lines, as described in the above-referenced Telescent patents. Inputs to the system comprise a plurality of lines  62 -in ( FIGS. 1A and 1C ) distributed in ordered columns and rows fed into one side of each individual one of an array of output couplers  18 , and are connected with low loss internal fiber connectors to an opposing array of input couplers  42 , and connected to a plurality of lines  62 -out at the opposite side of the system  200 . The individual rows are separately incrementally shiftable laterally by one of a stack of row shift actuators in accordance with the fundamental Knots and Braids methodology (referenced above). Changeable lines  52  are coupled into the second side of the individual couplers  18  and these lines converge into a one dimensional alignment at backbone  40  and are then distributed into ordered levels of multiple buffer reels  41 , as described below in more detail in relation to  FIGS. 11 to 13 . These reels  41  compensate for path length variations as internal fiber  52  positions and their corresponding suspended lengths are changed, without introducing curvatures in the optical fibers that are so sharp and non-adiabatic that they would introduce light loss at bends. From the assembly of buffer reels  41  the fiber pattern is reconfigured, typically into an array of linearly disposed output couplers or receptacles  18 , which can then be retransmitted or otherwise reconfigured as desired. 
         [0031]    Given this context, some principal aspects of the present invention that are also shown in generalized form in  FIG. 1A  (although shown and discussed in more detail below) further establish the internal cooperative relationships in form and function. For example, the arrangement of rows and columns of two-sided couplers in the connector assemblies  102  provide signal interchange between lines from opposite sides. On the internal, changeable side, the structures comprise individual linear fixed elements of predetermined length, cross-sectional configuration and flexibility. Each of these fixed elements also supports a pattern of small permanent magnets within its boundaries and adjacent its internal end as described in detail below with reference to  FIGS. 2 to 4 . In combination with this, each changeable optical fiber  52  in the system terminates in a connector assembly  102  of approximately matching length for coupling to any individual fixed element  63  with which it is to be paired. When a terminal protruding end of ferrule  10  of the optical fiber  52  is inserted in the individual union adapter  18  of the connector row assembly  102 , an individual changeable optical circuit is completed. Together with a number of features described in detail hereafter, that pertain either or both to design and operative relationships, this concept and its implementation are unique. 
         [0032]    Interrelated functions are provided in the system that pertain to the engagement and disengagement actuation operation as well as to the interchange of fibers to and from the couplers. Two different states of linear engagement and a related state of disengaged physical proximity are utilized, as is described in more detail below. These states are effected during a linear alignment phase independently of the repositioning of fibers by interweaving through the columns and rows as described in detail in the previously referenced patents. 
         [0033]    These as well as other functions are effected by commands from a trajectory control system  117  ( FIG. 1B ) which receives cross-connect configuration information from a server  109 , and a source of updated data, based on stored interconnection data from a memory system in server  109  holding updated data. Again, reference may be made to the patents mentioned above for a full understanding of the elements and relationships that are germane to positioning of the gripper assembly  103 . These movements are substantial in orthogonal X and Y directions and also incremental in the Z dimension under commands to the activator  103  from the trajectory control system  117 . For these functions the system  200  deploys a vertical multi-stage head positioner controlling movement in the Y axis, comprising a narrow rectangular hollow upper stage  30  inside of which a linear and narrower lower section  35  slides by spring-loaded rollers in a proportional ratio. Both receive command signals from the trajectory control system  117 , and are driven by a Y axis drive  33 - 1 , typically a brushless dc servomotor or stepper motor, responsive to command signals from the server  109 . The Y axis stages  30 ,  35  are moved horizontally as command signals are delivered from the trajectory control system  117  which activates the X axis drive  33 - 2 . Most of this mechanism is positioned above the fiber interchange matrix, while the narrow fiber interchange head  103  discussed in detail below ( FIGS. 5-7 ) is movable vertically in the spaces between the vertical column j of fibers  52  and indicated by  118 - j  in  FIG. 3 . The horizontal rows  102  of the interchange matrix are selectively moved incrementally in a first horizontal direction or oppositely during threading through the matrix. When the activated head  103  reaches a target location in  102  it can be moved incrementally along the Z axis to couple or decouple a target fiber connector  101  to the selected one of the target couplers  18 . Also, along the Z axis, it can shift the target connector incrementally between “allocate,” ( FIG. 5 ) “unallocate,” ( FIG. 6 ) and “unplugged” ( FIG. 7 ) positions. The corresponding magnet interactions between the connector  101  magnet  13  and to row magnets  14 ,  15  are noted in  FIG. 3 . 
       II. Two Dimensional Array of Switchable, Magnetically Latched, Multi-State Fiber Optic Connectors 
       [0034]    This application further discloses a multi-dimensional array of connector devices  101  arranged in incrementally shiftable vertically spaced rows  102  ( FIGS. 2-4 ) disposed in generally horizontally aligned columns as best seen in  FIGS. 3 and 4 . The horizontal rows, as best seen in  FIG. 2 , comprise a plurality of spaced apart parallel base elements each fixed at one end to a different union adapter  18  which is to receive the terminal ferrule  10  of a different and changeable fiber optic line  52 . Thus the array in part comprises, as seen in the perspective views of  FIGS. 1A, 3 and 4 , a plurality of horizontally spaced fixed elements  39  of selected flexibility and substantial length relative to their width and cross-sectional area. They are each fixedly attached at what can be called a receiver end to the transverse connector row assembly body  102 , and thus provide parallel interactive elements for receiving the individual fiber optic connectors  101 . These fixed elements  39  have a length to width ratio of greater than 10:1, and are of substantially less height than width so they have resilience in a selected range, and no or low magnetic permeability, since magnetic forces are to be used for specific deflection purposes therewith, as described below. 
         [0035]    Each optical fiber  52  in the system terminates in an elongated connector  101  leading to a ferrule  10  that engages in the union adapter  18 . When fully inserted, the optical fiber terminus  10  is in physical and optical contact with an external fiber terminus pre-existing in the opposite side of the coupler formed by the adapter  18  and in parallel adjacency to the fixed element  39 . As seen in the three different and adjacent insertion positions for the fiber ferrule  10  depicted in the partially exploded and fragmentary perspective view of  FIG. 2 , a detachable portion of the connector  101  extends from the ferrule  10  at the inserted end through a shaped, slightly larger housing  11  which limits the depth of insertion of ferrule  10  in the adapter  18  and provides the means to engage within a matching receptacle in underside of gripper  103 . The removable part further includes an intermediate section of elongated U-shaped housing  80  of a predetermined length that provides an external wall that substantially surrounds and protects the optical fiber  52 . This housing member  80  encompasses an internal length of optical fiber that couples at one end to the ferrule  10  and merges at the other end with an individual different optical fiber  52  in the system. The movable connector  101  also includes a gripper latch receiving element  12  intermediately positioned along its length and a small magnet  13  of high permanent magnetic field strength at a predetermined substantial spacing from its terminal ferrule  10  which provides cooperative functions described in detail below. 
         [0036]    The connector  101  also provides predetermined optical, mechanical and magnetic interaction with the system in general and with each different adjacent elongated fixed element  39  in particular. Since, as seen in  FIG. 2 , each such fixed element  39  extends from the underside of a union adaptor  18  in parallel adjacency to a movable fiber optic connector  101  therein, it incorporates a number of cooperative features along its length. Starting from the free end, the fixed element comprises a pair of bifurcated end sections serving as supportive bases for two small permanent magnets  14 , of the same selected polarity, at like distances from the union adapter  18  end. These may be termed the “unallocate” magnets, to designate their operative function, while a third magnet  15  is centered on the elongated body at a predetermined small lengthwise spacing from the magnet pair  14 , and may be termed the “allocate” magnet. The third “unplugged” state shown in  FIG. 3  is one that exhibits little magnetic attraction between the inserted magnet  13  and any of the magnets  14  and  15  in the fixed element. The fixed member  39  also includes a short, slightly narrowed docking section  16  intermediate its length, and an adjacent reflector surface  17  that can be used in positioning. 
         [0037]    The three different positions of relative engagement of the connector  101  are depicted in  FIGS. 2 and 3 . The “allocate” state, as used herein refers to a relationship in which the ferrule  10  of the fiber connector  101  is fully engaged within the mating sleeve of the adaptor  18 . The term “unallocate” refers to the state wherein the fiber connector is partially engaged within the mating sleeve  18 . The “allocate” state produces near zero insertion loss and the “unallocate” state produces about 20 dB or more loss by virtue of the air gap between the fiber connectors. “Unplug” refers to the state in which the fiber connector is fully withdrawn from the mating sleeve, wherein the gripper is able to withdraw a connector  101  from its corresponding connector port  55  for movement to a different destination  55 . 
         [0038]    In a preferred exemplification, the four magnets  13 ,  14 ,  15  are about 6 mm×6 mm×3 mm in size, and their material is Neodymium 42SH. This magnet grade provides high magnetic attraction force of at least 500 gram-force in “allocate” state, and also maintains magnetic properties even when exposed to high temperatures (above 150 degrees C.). The N-S magnetization axis is typically parallel to the 6 mm side. Ideally, the magnets are nickel-plated so they can be soldered to metalized pads of the printed circuit board connector row using a standard solder reflow process. 
       III. Parallel Rows of Fiber Optic Connectors that Independently Translate Laterally Under Software Control 
       [0039]    A portion of the automated cross-connect structure  200  in the present invention thus comprises a stacked arrangement of independently translatable connector rows which form a two dimensional array of ports. A particular example with eight vertically stacked connector rows  102  with a vertical spacing of about 12.5 mm is depicted in  FIGS. 3 and 4 . In this particular example, each row  102  is comprised of twelve parallel connector tracks each spaced transversely by about 32 mm. Each connector track is elongated and narrow and has selected flexure properties. The N-S polarity and arrangement of magnets  14 ,  15  at the distal end of each connector track are identical for each track and row. As a consequence, when the rows are in horizontal (x) alignment as shown in  FIG. 4 , the magnets  14 ,  15  on each row cause the distal ends of each connector track  39  to repel one another in the x and y directions. These repulsive forces are effectively positioned to partially magnetically levitate the narrow semi-flexible connector tracks  102  and reduce the potential for interference of adjacent rows of extended members  39 . 
         [0040]    In the absence of magnetic levitation of fixed members  39  detailed in  FIG. 2 , deflection of the extended connector track could otherwise occur due to the tension vector of the fiber optic connector  101  engaged therein. The minimization of deflection is effective to eliminate potential jamming of vertically adjacent rows and the fiber connectors seated therein during the independent row shuffle process. 
         [0041]    In further accordance with this invention, each connector row is supported at opposite ends by sets of three miniature rotary bearings mounted in bearing blocks  43 ,  49  that provide guidance in the two axes (x, z) parallel to the surface of the connector row, and support it above the lower row. Each bearing rides within its own track within an injection molded plastic guide block  45 ,  46  on the left and right ends respectively, as viewed in  FIG. 4 . A central support roller  38  further provides a mechanical reference point at the center of the row to preclude a potential slight bowing along its length of the mechanical row assembly  102 . This reference surface provides adequate support to prevent large deflection of the connector row during gripper engagement when the gripper mechanically latches onto a particular track  39  of the connector row. 
         [0042]    Preferably, the connector row  102  is comprised of a printed circuit board substrate made of common circuit board materials such as FR-4 with a thickness of 2.4 mm for high stiffness. This material is flat, stiff, inexpensive, and facilitates the reliable placement and soldering of magnets onto the circuit board. The ability to add circuitry also enables the implementation of RFID tracing of connectors as well as optical power monitoring and detection. 
         [0043]    Each connector row  102  is independently shiftable by a motor  20 - 1 , only some representative examples of which are seen in  FIG. 4  and which are shown as a unit of four motors in  FIG. 1A . This motor  20 - 1  is typically a linear permanent magnet dc stepper motor that provides precise, programmable linear translation of the row over about 37 mm range of travel. The low friction of the bearing track assemblies  43  and  44  ensures that only a minimal force (&lt;100 gram-force) and low current are required to actuate each row. 
         [0044]    As seen in the perspective views of  FIGS. 3 and 4  of the connector row subassemblies  102 , the narrow elongated elements  39  in each row are positioned to define like vertical columns or stacks of elements  39 . These elements are horizontally separated from each other by a standard distance which in this example is about 37 mm. For clarity only one fiber connection assembly  101  is depicted in the upper view of  FIG. 3 , and shown as coupled to an internal fiber  52  leading to an external buffer port (not shown) in the system. It will be understood from the referenced previously issued patents that interweaving through the three-dimensional mass of fibers  52  is effected by laterally shifting the rows of elongated fixed elements in timed relationship to the instant vertical position of the fiber transport. The fiber is thus repositioned by being interwoven through the existing pattern of fibers, without entanglement, until it reaches its destination, where it is engaged in the terminal thereat, as described in the earlier issued patents. 
         [0045]    Those skilled in the art will appreciate the problems that can potentially be encountered when navigating a thin element such as an optical fiber through a dense population of other optical fibers. In this respect, the employment of static small magnetic elements on narrow elongated elements to provide strategic magnetic attraction and repulsion forces, offers material benefits in the form of the presently disclosed system, both as to changing positions of elements and in maintaining stable operating states. 
       IV. Narrow Form Face Gripper to Selectively Transport, Install and Reposition Fiber Optic Connectors in a Dense Matrix 
       [0046]      FIGS. 5, 6 and 7  illustrate an electronically actuable gripper device  103  changeably interlocked or docking with a typical connector row  102  to produce adequate local actuation force at the connector  101  to vary the position of a fiber connector  101  in the two dimensional array of output ports  81  as best seen together in context in  FIGS. 1-4 . The gripper is shown in three primary states of axial engagement corresponding respectively to the fiber connector  101  being“allocated” ( FIG. 5 ) (or operatively engaged), “unallocated” (or partially inserted) ( FIG. 6 ), or “unplugged” or fully disengaged ( FIG. 7 ) from the connector and free to be moved elsewhere (or inserted). The gripper  103  descends onto the connector row and stops upon optically detecting engagement with a particular individual track element  18  of the connector row  102  using a reflective optical photo-interrupter sensor  27 - 6 . The light from the sensor is reflected from the edge of the connector track by a reflective plating  17  ( FIG. 2 ), which is typically gold, and instructs the trajectory control system  117  ( FIG. 18 ) that the gripper is properly docked onto the track element  18 . The interlocking is accomplished by mechanical engagement of the gripper guides  20  with the reduced-width docking section  16  (as best seen in  FIG. 2 ) present on each track element  18 . The gripper subsystem comprises two closely adjacent printed circuit boards  60  and  29  lying in the narrow vertical plane which extends down to any selected row, the gripper subsystem also including multiple sensors and actuators. The upper circuit board  60  is attached to the lower end  35  of the telescopic robot actuator (see  FIG. 5 ). The adjacent lower sliding circuit board  29  is mounted on a linear bearing assembly, including parallel horizontal upper and lower shafts  26 - 1  and  26 - 2  respectively, so that this portion of the gripper, which is not fixed to the closely adjacent gripper board  60 , can translate horizontally in either direction between closely spaced limits within the same narrow columnar region as the fiber connector  101 . Sensors  27 - 1 ,  27 - 2 , and  27 - 3  detect the translation of the overlapping but lower circuit board  29  in the allocate, unallocated and unplug locations, respectively, as the distance d decreases from d 1 , d 2  to d 3 , respectively. The lower sliding circuit board  29  includes mechanical elements  79 ,  80  spaced along its length that can retain ( 79 ) and lock ( 80 ) onto the length of the fiber connector  101 . Optical sensors are typically reflective and/or transmissive photo-interrupters. A solenoid  23  responsive to control system  117  triggers a spring loaded mechanical latch  24  within the locking element housing  80 , wherein the state of the latch is detected by reflective photo-interrupter sensor(s)  27 - 4  and  27 - 5  integrated on electronic circuit board  29 . In a particular example, translation of the gripper device  103  is powered by a motor  32  and timing belt drive consisting of a timing belt pulley  28  and timing belt  25 , or a high efficiency drum/wire drive system. 
         [0047]    In a further example, to identify fibers based on their barcode and to provide machine vision alignment, the gripper  103  may further include a camera  21  and LED illuminator  22  to capture images of the connector  101  and its unique barcode identifier. Alternatively, the reel encoder circuit  51  enables any fiber to be uniquely identified by monitoring the reel encoder sensor signal  72  as the fiber is transported by the gripper. 
         [0048]    In a particular example, the gripper  103  provides about 19 mm of linear travel, sufficient to allocate ( FIG. 5 , d 1 ), unallocate ( FIG. 6 , d 2 ), or unplug ( FIG. 7 , d 3 ) the connector  101  as commanded where the incremental distances d 1 , d 2  and d 3  are approximate as depicted. When unplugged, the connector  101  can be transported vertically without interference through the lateral volumetric space  118 - j  extending from the top to bottom of any particular column j, between and independent of all other fibers in the matrix. When a connector assembly  101  is delivered to its destination track  39  on the connector row, its forward tip  10  is adjacent but spaced apart from the chosen fixed connector in the assembly of connectors  102 , as seen in  FIG. 7 . The gripper assembly  103  is thus held in the “unplugged” position, as seen in  FIG. 7  prior to allocation. In this mode the lower planar circuit board  29  of the gripper assembly  103  is spaced apart from the connector  102 . The gripper guide  20  remains fixed as the lateral position of fiber connector assembly  101  changes. Full engagement is seen in the view of  FIG. 5 , in which the lower printed circuit board  29  has been shifted to the left by the actuated gripper assembly  103  in response to energizing the motor  32  of gripper actuator. This is the “allocate” position, in contrast to  FIG. 6 , which shows the “unallocate” or partially engaged position, and  FIG. 7 , in which there is no connector engagement. 
       V. Telescopic Robotic Vertical Actuator 
       [0049]    The gripper device  103  is mounted on the lower end of, and is transported by, a two-axis robot mechanism  104  as illustrated in  FIGS. 1A, 8A, 9, 10A, 10B and 10C . The robot device  104  is telescopic in the vertical direction to enable the gripper device  103  to reach a large number of cross-connects within a height constrained installation. It comprises a rectangular outer arm or stage  30  and an inner arm or stage  35 , and is movable in the horizontal direction by a drive belt  25  or wire/string extending between fixed end points. The vertical telescoping and horizontal movement capability ensures that the arm can reach all connectors within the two-dimensional array of rows of connector ports  55  ( FIG. 2 ) without adding excessive height to the overall robotic cross-connect system above the 2.15 meter height standard preferred by the industry. 
         [0050]    Telescopic robot arms in the prior art do not have the required stiffness nor the aspect ratio/miniaturization needed to descend and operate in between the internal fiber connectors with requisite positioning accuracy (˜+/−3 mm) of the internal connector with tensioned fiber attached. In the present system, however, a vertical linear outer stage  30  of a slender hollow rectangular or partial rectangular cross section receives a sliding interior member  35  of smaller cross section. As seen in  FIG. 10B  the top end of the inner stage  35  of the robot arm includes an internal carriage  76  that spring-loads roller bearings  92 ,  93 , which contact the inner side walls of the rectangular or “C” shaped hollow cross section outer arm  30 . In the preferred embodiment the outer stage  30  and inner stage  35  are stainless steel or plain steel; however, aluminum, plastic, fiberglass and carbon fiber are all suitable alternatives. 
         [0051]    The gripper mechanism  103  is attached to the lower end of the inner stage  35  of the robotic arm system, which telescopes within the tubular outer stage  30  and variably extends in length, as seen in  FIGS. 9 and 10A . The electrical cable  37  carrying electrical signals for the sensors and actuators embedded within the gripper  103  travels up the inner stage  35 , then through the outer stage  30 , exits the top of the outer stage  30 , wraps around an upper pulley  31  and then extends down to a fixed attachment point at  36 . As seen in  FIGS. 8A and 9 , a y axis motor  33 - 1 , for example a dc servomotor or stepper motor, drives the tubular outer stage  30  up and down through a timing belt drive mechanism attached to the top and bottom of the stage  30 . The multi-conductor electrical ribbon cable  37  is rigidly affixed to the top of the inner stage  35  and its midpoint is fixed at a cable attachment point  36 . As the outer stage  30  moves up and down ( FIG. 8D ), the inner stage  35  moves at twice the outer stage distance because of the action of the cable  37  looping over the pulley which is attached to and moves with the outer stage. 
         [0052]    The telescopic arm exhibits relatively low transverse compliance or equivalently high rigidity. In a particular example, less than 2 mm of deflection results for about 50 gm of transverse force applied perpendicular to the telescopic direction (i.e. in x and z directions defined in  FIG. 1 ) and high length efficiency (ratio of the telescopic arm range L 2 =1.5 meters to arm retracted height L 1 =1 m,  FIGS. 9, 10A, 10B ). This rigidity is important to prevent the tension from the fiber  52  attached to connector  101  from dragging or deflecting the telescopic arm out of true vertical alignment. In contrast to prior art telescopic arms (e.g. drawer slides, telescopic booms, etc.), the transverse compliance is independent of extended length L 2  L 2 ′ (0 to 1.5 meters) of the telescopic structure. This is a significant advantage of the present invention, because reliable engagement of any connector  101  across the extended front connector array, by gripper  103 , also requires some non-zero level of deflection and consistent deflection and compliance characteristics to enable automatic, passive alignment via the mechanical capture method. On the other hand, low vibration at all locations of the connector array at the end of the telescopic arm should also be maintained. 
         [0053]    In accordance with the invention, tightly controlled compliance characteristics are achieved by (1) providing a roller bearing system for the outer, first stage that is very stiff and (2) providing a roller bearing carriage for the inner, second stage, wherein a set of bearings are located at the upper 150 mm of the inner, second stage, suitably preloaded by mounting the inner carriage bearings on flexures  76 - 1 ,  76 - 2  so that the carriage is guided within the tube  30  with high angular consistency. The bearing system is illustrated in part in  FIGS. 10B and 10C  and is comprised of internal x axis support bearings  92 , and internal z axis support bearings  93 . To preload the system there are further preloaded internal x support bearings  92 ′ at opposite, suspended ends of flexure  64  and preloaded internal z support bearings  93 ′ at opposite, suspended ends of flexure  76 . 
         [0054]    The bearing flexures  76 - 1 ,  76 - 2  are, for example, semi-hard stainless steel sheet metal structures deflecting under load like a leaf spring, with radial ball bearings  93  attached at both ends of the flexure arm. Mechanical stress arising from deflection is by design smaller than the yield stress of the material, thereby preventing the flexure from permanently deforming. These flexure arms  76 - 1 ,  76 - 2  are affixed to the rigid, steel inner second stage at the top of the stage  35  so that the opposite bearings are preloaded and in contact with the outer tube as they ride up and down the inner cavity of this outer first stage  30 . The friction of the bearing assembly is sufficiently low that the inner stage descends controllably within the outer tube due to gravity alone and is supported by the electrical ribbon cable  37 . This cable serves two purposes: it resists gravity preventing the arm from dropping and transmits signals from the gripper  103  to the trajectory control system  117 . This cable  37  is routed around the pulley  31  attached to the top of the outer stage  35  and affixed to the main robot x axis carriage  61 . 
         [0055]      FIG. 8B  is a schematic top-view of the horizontal or x-axis carriage drive system, consisting of a timing belt  25 - 1  with drive pulley  28 - 2  coupled to the x axis servomotor  33 - 2  with gearbox at one end, and an idler pulley  28 - 1  at the opposite end. The x-axis platform  61  is attached to timing belt  25 - 1 , which translates the platform from one end of the x rail to the other end. 
         [0056]      FIG. 8C  is a schematic side-view of the y-axis actuation system, detailing the timing belt pulley drive system. A first timing belt  25 - 2  is affixed at opposite ends to the outer y axis tube  30  and is used to drive the tube  30  up and down. Timing belt  25 - 2  is redirected and wrapped around timing belt drive pulley  28 - 6  by a pair of idler rollers  28 - 7  and  28 - 4 . Drive pulley  28 - 6  and reduction pulley  28 - 5  are rigidly attached to a common central shaft  28 - 6 . The drive motor  33 - 1  turns a small drive pulley  28 - 3 . A timing belt  25 - 3  wraps tightly around both a small diameter pulley  28 - 3  and a spaced apart large diameter pulley  28 - 5 . The ratio of large to small pulley diameters is typically 5 to 10 to produce a torque multiplier. 
         [0057]    As depicted in  FIG. 8D , driving the outer arm  30  with the timing belt raises or lowers the pulley  31  by a corresponding distance X, since the pulley  31  is mounted to arm  30 . The pulley  31  is free to spin. A fixed length elongated band or wire  37  is attached at one end to a fixed point  36  of y drive platform, and the opposite end is attached to topmost portion of inner stage  35 . This configuration results in the robot arm inner stage  35  moving at 2×, twice the distance of the robot arm outer stage  30 .  FIG. 8D  illustrates the configuration of the arm at various degrees of telescopic extension. The wire  37  is wrapped around moving pulley  31 . For a particular distance X 1  the outer arm  30  moves, the pulley also moves in the same direction the same distance X 1 . Since the cable is a fixed length and suspends the inner stage  35 , as the pulley moves a distance X 1  the translating end of the cable moves by a distance 2X 1 . As a result, the inner stage  35  moves a distance 2X 1 . 
         [0058]    A particular exemplification of the gripper shown in  FIGS. 8E, 8F and 8G , to which reference is now made, details a drive mechanism for reliably incrementing a selected optical fiber mounted on the fixed printed circuit board  60 . The gripper includes a stepper motor  32  which rotates a gripper drive drum  122  on which a cable  25 ′ is wrapped with a controlled looseness or “play.” The winding of wire  25 ′ on drum  122  pulls the outer structure  29 , riding on parallel rods  26 - 1 ,  26 - 2  to the right (as shown by the arrow in  FIG. 8F ) by tightening the portion of wire  25 ″, seen here on the left side of  FIG. 8F , or left ( FIG. 8G ) by tightening the portion of wire  25 ″ as seen on the right side of  FIG. 8G . The provision for a chosen degree of slack within the wire provides a significant improvement in the amount of torque and corresponding linear actuation force available from a given stepper motor. Under typical operating conditions, the motor  82  must drive the gripper from an initial position of maximum resistance, thereby requiring the maximum torque at the start of motion. If the wire has no slack, the motor would need to overcome a large initial force as it accelerates. This is the force to plug-in or un-plug an internal LC connector  101 . It is known in the art that stepper motors stall under conditions of high torque during an initial start-up acceleration. By providing a length of slack wire  25 ′ on each side of the drum  122 , the motor initially experiences only minimal load as it takes up slack by winding excess wire on drum  122 . As a result, the motor is not subjected to the large load until after (1) it reaches a minimum velocity/is no longer in acceleration phase and (2) the wire no longer exhibits slack in taut section  25 ″ on one side or the other (e.g.  FIGS. 8F, 8G ). 
         [0059]    The stepper motor pull-in torque is the measure of the torque at which the stepper motor will stall when it is starting from rest. The pull-in curve defines an area called the start/stop region. When operating with proper selection of parameters such as velocity, acceleration and load torque, the motor can be started instantaneously with a load applied and without loss of synchronism. The slack wire in the cable drive ensures that this load torque is initially low ( FIG. 8H ). In contrast, stepper motor pull-out torque is the torque that can be produced at a given velocity until the motor stalls. The pull-out torque is typically at least a factor of 2 higher than the pull-in torque. It is therefore advantageous for the gripper stepper motor to operate in the pull-out torque regime when experiencing the largest loads associated with plugging-in/unplugging internal connectors  101 , to ensure the maximum torque output for a given z drive system. 
       VI. Slack-Fiber Take-Up Reels and Rotation Sensing 
       [0060]    The fiber connectors in the assembly  101  terminate as output fibers  52  ( FIG. 11A ) from low profile spring-loaded reels  41  ( FIG. 11B ) that are arrayed on a planar, low profile tray  47 , as shown in  FIGS. 11A to 13A . This example of a fiber tray assembly  106  ( FIGS. 11A and 11B ) includes twelve fibers that are rendered individually and independently self-tensioning, by reels  41  to which the fibers  52  are guided after passing through a center backbone of linearly arrayed flexible guides  40 . Flexible guides are typically a low friction tubing material such as PTFE, FPA, FEP, etc. In the particular example shown here, the opposite ends of each of the twelve fibers exiting the backbone have originated in connectors that are plugged individually into different ones of a linear array of union adaptors or mating sleeves  18 . The internal paths of the fibers  52  between the interior reels  41  and the output connector array  42  are depicted in  FIG. 11B . 
         [0061]    The fragmentary perspective view of  FIG. 12  details the paths of the fibers to individual reels including front, dynamically moving fibers  52  exiting from the reel fiber exit location  50  and terminated in connectors to form the dynamic output connector array  81  ( FIG. 1A ), and rear, fixed length fibers  54  ( FIG. 11B ), also exiting from reel location  51  and ultimately terminated in connectors to form the static input connector array  82 . As seen in  FIG. 12 , the fibers are routed through O-ring eyelets  49  and around rollers  48  to redirect the dynamically moving fibers with low friction and low stress as they experience an angular change of about 90 degrees while passing around an intervening reel  41 . As the fibers  52  are withdrawn or retracted back into a reel, the reel  41  rotates, causing the reel&#39;s internal fiber to spiral on its underside (as disclosed in U.S. Pat. No. 8,068,715) so as to coil or uncoil, respectively. As seen in  FIG. 13A , the outer wall of the reel is segmented and/or colored with alternating reflective/non-reflective circumferential segments  46  such that a reflective photo-interrupter  45 , in combination with an electronic multiplexing and counter circuit  51  detects the number of turns the reel undergoes. This provides validation during operation that the proper length of fiber  52  is present on the reel as a function of the movement of fiber connector  101  during robot control. 
         [0062]    Different novel aspects of an improved multi-reel module are also depicted in  FIGS. 11 to 13 .  FIGS. 11A and 11B , for example, illustrate an advantageous geometric layout of twelve reels  41  for providing individually adjustable lengths of optical fiber. Here, each fiber tray assembly  106  distributes individual optical fibers from the backbone  40  to reels  41  which are linearly aligned in spaced apart sets of four extending from front to back on the tray  47 . Furthermore, these reel sets are each adjacently positioned so that the pairs of adjacent reels each define an acute angle relative to the front to back axis on the tray  47 . There are thus six reels on one side of the tray  47 , and six reels on the opposite side positioned in oppositely angled pairs with an open central area of the tray  47  providing a pathway to input fibers from the backbone  40  input. 
         [0063]    The fiber inputs  52  to the different reels  41  feed into the central area and are directed clockwise about the individual reels in the left (as seen in  FIG. 11B ) side set of six reels, and counterclockwise about each of the six reels on the right-side set. Since the reels of each pair are closely adjacent but spaced apart, the paths of fibers incoming from the central backbone  40  are different, dependent on whether a reel is the innermost one of the angled pair, or the outermost one of the pair. The problem is resolved, while still maintaining compactness and control, by the fiber guide geometry shown in  FIG. 12 , to which reference is now made. The inner (closest to the center) reel  41  of an angled pair receives a variable length of fiber  52  to take up or supply fiber as needed during reconfiguration. The variable length reconfigurable, auto-tensioned fiber  52  is controllably guided with curvature of greater than a minimum acceptable bend radius (typically &gt;5 mm). The reels of each pair are closely adjacent but operatively distinct, which result is made possible by the angled and spaced geometry of the reels  41  of any module. At the opposite end of the fiber, a fixed rear length of fiber  54  is fed to the individually coupled rear union adapter  42  ( FIG. 11 ). 
         [0064]    A useful novel expedient for monitoring the dynamic operation of the multiple reels  40  is provided by the sensor arrangement depicted in  FIG. 13A  and an example of the associated multiplexing circuitry as depicted in  FIG. 13B . Referring to those figures it can be seen that a small reflective photo sensor  45  is mounted in a thin wall adjacent the periphery of a take-up reel  41 . The sensor  45  is positioned outside the take-up reel and generates a signal which varies with the then adjacent circumferential segment of the take-up reel  41 . There are, as seen in  FIG. 12 , seven such indented (small radius) segments, evenly distributed around the periphery of each fiber take-up reel  41 . Thus, as the reel rotates to feed out or take up fiber, a responsive signal from the associated sensor  45  is sent to reel encoder circuits  51 . These circuits  51 , one for each individual reel  41 , provide signals responsive to the changing rotational position of the reel. To read out any particular sensor, the electronic multiplexers  70 ,  71  in the internal monitoring system must be set to its particular address. As shown in  FIG. 13B , multiple individual power and ground lines from different sensors  45  can be shared by feeding into separate multiplexer circuits  70 ,  71  to selectively activate a particular reel and generate signals  72  corresponding to its particular reel  41 , for processing by command circuits  51  which monitor the operation of the multiple reels. 
       VII. Automatic Fiber Endface Dry Cleaning Cartridge with Integral Sensing for Process Control 
       [0065]    Reference is now made to  FIGS. 14, 15, 16A and 16B , which illustrate partial cutaway and perspective views of an advantageous cleaner device  105  detailing how force sensing is effected by means comprising a compliant pad  57  behind a cleaning fabric  58 , further including a force sensor  56  within the compliant pad  57  which detects the existing ferrule tip compressive force F, the direction of which is indicated by the block arrow in  FIGS. 14 and 15 . A fiber connector  101  within the gripper  103  is raised to above the fiber interconnect volume and the top most fiber module  113 - 10  along the y axis so that the connector is at the elevation of the cleaning cartridge  105 . The cleaning cartridge is mounted rigidly to the bottom of the translating x axis carriage  61  and moves with the carriage as it translates in x. The cleaning fabric is advanced by moving the robot to the far right, to depress the cleaning cartridge advance lever  75  which advances the cleaning fabric to a clean, unused portion of the fabric. In a particular example, the force sensor  56  is a substantially planar element on a flexible substrate with internal electrode features that include two wire terminals  59 , and produces a resistance change proportional to the average local force within the sensing region. The sensing region is typically 5 to 10 mm in diameter and the thickness of the sensor is typically 0.25 to 0.5 mm. The sensor wires  59  are interfaced to an external electronic circuit  107  including a voltage divider, wherein the target force sensing threshold is 100 gm-F and the reference resistor value of the voltage divider is selected to produce a voltage of about 2.5V for a supply voltage of 5V. A typical resistance crossing value for the force sensor is 1001M and the reference resistor is typically chosen to be 1MΩ. A comparator in the circuit  107  converts the analog voltage on the voltage divider into a digital signal. This digital signal is input to a controller  108  and monitored by embedded control software to accurately terminate the gripper  103  and fiber  101  advancement at the prescribed cleaning fabric compression force. The robot gripper  103  ( FIG. 14 ) moves the fiber end face  10  of the connector  101  until the fiber end face touches the fabric and compresses the compliant pad  57  behind the fabric. The force sensor is integral to the compliant pad  57  and senses the compression therein. The desired force for automated cleaning is in the range of 25 gm-F to 250 gm-F. Control of force within a range is important because excessive force can create tears in the fabric and contaminate fiber; inadequate force can result in incomplete cleaning. 
         [0066]    Furthermore, in accordance with the invention, the cleaning cartridge  105  which is disclosed provides integral sensing of the cleaning fabric consumption. Referring to  FIGS. 16A and 16B , the cleaning cartridge includes sensing means, such as a reflective photo-interrupter  77 , to detect the advance of the cleaning fabric  58  from its spool, feeding its signals to the electronic circuits  107  and  108  ( FIG. 14 ). The cleaning cassette fabric  58  is fed from the supply spool  73  past the cleaning cassette pad  57  and the sensor  56  to the dispense spool  74 . The cleaner advance lever  75  is actuated to feed the fabric  58  in increments as needed by horizontal movement along the x axis to depress the lever when it strikes the hard stop in the vicinity of the rightmost limit of travel. As is evident from the perspective view in  FIGS. 14 and 15  of the relationship of the gripper assembly  103  when it is in operative relationship to the cleaning cartridge  105 , the supply spool  73  and dispense spool  74  straddle the cleaning cassette pad  57 . The spacing between the two spools thus facilitates accessing any chosen optical fiber ferrule  10  in operative position for cleaning and return to operative position in the precisely ordered bank of changeable optical fibers. At the same time, the source of cleaning material is large enough for many different cleaning sequences, but readily replaced when adequately used or when an inspection is needed. 
         [0067]    In conclusion, new mechanisms and designs to achieve reliable operation of compact, robotically reconfigured, software-defined fiber optic patch-panels are disclosed herein. Those skilled in the art will readily observe that numerous modifications and alterations of the devices may be made while retaining the teachings of the invention. 
       VIII. Appendix 
     DRAWING LEGEND 
       [0000]    
       
         
           
               10  Polished fiber ferrule 
               11  Plastic connector housing 
               12  Gripper mechanical locking feature 
               13  Connector magnet 
               14  Connector row unallocated magnets 
               15  Connector row allocate magnet 
               16  Reduced width mechanical feature for docking 
               17  Edge plated reflector 
               18  Fiber optic union adapter 
               19  Connector row actuator 
               20  Gripper guides 
               21  Camera 
               22  LED illuminator 
               23  Solenoid 
               24  Latch of solenoid 
               25  Cable or timing belt 
               25 ′ Loose cable drive 
               25 ″ Taut cable drive 
               26  Gripper translation shaft 
               27  Reflective photo-interrupter 
               28  Timing belt pulley 
               29  Gripper sliding printed circuit board 
               30  Robot arm outer stage 
               31  Telescopic arm cable pulley 
               32  Gripper actuator 
               33  Motor 
               35  Robot arm inner stage 
               36  Fixed cable attachment point 
               37  Electrical cable 
               38  Central support roller for row 
               39  Connector track 
               40  Backbone with flexible guides 
               41  Fiber take-up reels 
               42  Rear fiber optic union adapters 
               43  Left bearing block 
               44  Right bearing block 
               45  Reflective photo sensor 
               46  Reflective reel segments 
               47  Tray for reels 
               48  Fiber rollers 
               49  Ring eyelets 
               50  Reel fiber exit location 
               51  Reel encoder PCB 
               52  Internal, reconfigurable, auto-tensioned fibers 
               53  Reel axis of rotation 
               54  Rear, fixed fibers 
               55  Reconfigurable fiber optic connector ports 
               56  Cleaning cassette sensor 
               57  Cleaning cassette pad 
               58  Cleaning cassette fabric 
               59  Pair of electrical wires from force sensor 
               60  Gripper center printed circuit board 
               61  Robot x carriage 
               62  External fibers 
               63  Output fiber connector mount 
               64  Magnetic steel insert 
               70  Column electronic multiplexer for sensor 
               71  Row electronic multiplexer for sensor 
               72  Reel encoder sensor signal 
               73  Cleaning fabric supply spool 
               74  Cleaning fabric dispense spool 
               75  Cleaner advance lever 
               76  Spring loaded rollers 
               77  Cleaning fabric usage sensor 
               78  Output connector array support structure 
               79  Gripper connector retaining feature 
               80  Gripper connector locking feature 
               81  Dynamic two dimensional array of output ports 
               82  Static two dimensional array of input ports 
               101  Fiber connector assembly 
               102  Connector row assembly 
               103  Actuated gripper assembly 
               104  Two axis robot 
               105  Cleaning cartridge 
               106  Fiber tray assembly 
               107  Voltage divider, mux &amp; comparator circuit 
               108  Controller &amp; logic 
               109  Server module 
               110  Ethernet switch module 
               111  Power management module 
               112  Robot module 
               113  Fiber module 
               114  Docking module 
               115  Optical power monitor module 
               116  Gripper sensor circuit 
               117  Trajectory control system 
               118  Gripper travel location within column gaps 
               119  Projection of fiber trajectories onto xz plane 
               120  X axis drive 
               121  Y axis drive 
               122  Gripper drum 
               200  Automated patch panel system