Abstract:
A machine for automatically tying a four-in-hand necktie knot in a necktie, includes ( 1 ) a horizontal rotatable cylinder; ( 2 ) a hooking mechanism capable of pulling a left hand short segment of the necktie through a loop of a right hand long segment of the necktie hanging from the rotatable cylinder; ( 3 ) a finger mechanism capable of laterally moving the right hand long segment along the length of the rotatable cylinder; ( 4 ) a whirler mechanism capable of flipping an end of the right hand long segment around the rotatable cylinder and up through a space between the right hand long segment and the left hand short segment and the necktie support, and ( 5 ) an electronic and feedback control for operating various mechanisms in response to a sequence of voltage commands.

Description:
This application claims the benefit under 35 U.S.C. 119( e ) of provisional application No. 60/364,925 filed Mar. 15, 2002, in the name of Seth R. Goldstein, the disclosure of which is incorporated by reference in its entirety. 
    
    
     BACKGROUND AND SUMMARY OF INVENTION 
     I have conceived, built, and successfully operated a machine that ties and then unties a necktie, using a four-in-hand necktie knot. The machine consists of 10 different electric motors that are coordinated by a computer so as to perform the above tasks on a tie hung from a platform located above the motors. The purpose of the machine is for entertainment although in principle, after the tie is tied, it could be removed from the platform and hung on a person&#39;s neck as if it had been manually tied. 
     Each of the ten electric motors has an integral gearhead whose output shaft is attached to a potentiometer that provides feedback to an electronic power operational amplifier that drives the motor resulting in servomechanism operation that is well known to feedback control engineers. Each output shaft has an attached lever or pulley wheel or specially shaped structure to accomplish a given type of task (e.g. pulling or pushing or rolling or grabbing the tie) within the overall cycle. The motors are located on posts several feet high projecting up from a heavy baseplate approximately 1.5×3 feet in size that in turn is mounted upon a wooden base. The input to each of the 10 servomechanisms, which controls how far it is to rotate, is an analog voltage coming from a D/A converter controlled by a personal computer. The computer runs a program that sequentially reads out a data set line by line. The data in each line consists of a first number which selects which motor is to be operated, a second number which determines how far it is to rotate, and a third number which determines how long the computer is to wait before reading out the next line, e.g. typically the duration of the motor motion. In the current version of the data set that successfully ties and unties the necktie, there are approximately 550 lines. It takes approximately 6 minutes to sequentially read out all of these lines, and therefore to tie and untie the necktie. 
     The most difficult challenge in automatically tying the four-in-hand knot is to push the wider part of the tie (henceforth labeled RT—for right tie) through the space between the first and second wraps of the RT around the narrow part of the tie (henceforth called LT—for left tie). In my design this guidance of the mechanically manipulated RT is facilitated by pulling the RT through a 3 inch diameter horizontally oriented support tube about which rotates an outer rotating tube over which RT has been previously wrapped (the second wrap). The first wrap of RT around LT has previously been manipulated to be outside and behind both concentric tubes so that when the RT is pulled through the support tube, it is automatically located between the first and second wraps. This use of a tube to guide RT as described above dominates the design and operation of the machine. It is explained more thoroughly in Section IV Method of Operation and in the various parts of FIG.  12 . The rotary and support tubes can be raised and lowered a distance comparable to the length of the suspended RT. A horizontal tab is attached to the periphery of the rotating tube at its left end. When RT is engaged in the tab and the tube is rotated, RT can be wrapped around the tube by an amount controlled by the tube rotation. In summary, the support tube can be vertically moved to position the outer rotating tube at different heights and the RT ultimately gets pulled through the inner support tube. Hereinafter the term tube assembly is used to stand for the concentric rotary and support tubes. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1A (front view); FIG. 1B (right end view); and FIG. 1C (top view) are schematic diagrams of the tube assembly that is used to form loops of the tie and guide the placement of the end of the tie through the appropriate loops. 
     FIG. 2 is a schematic illustration (left end view) of the vertical moving assembly and the attached tube assembly. 
     FIG. 3A (front view) and FIG. 3B (top view) are schematic diagrams of the hooker assembly and its attached crank assembly. 
     FIG. 4A (front view) and FIG. 4B (right end view) are schematic diagrams of the whirler assembly. 
     FIG. 5A (front view) and FIG. 5B (right end view) are schematic diagrams of the finger assembly. 
     FIG. 6A (front view) and FIG. 6B (top view) are schematic diagrams of the grabber assembly. 
     FIG. 7 is a schematic diagram (front view) of the breaker assembly. 
     FIG. 8A (top view) and FIG. 8B (front view) are schematic diagrams of the tie support assembly. 
     FIG. 9 is an overall signal flow diagram of the electronic controls. 
     FIG. 10 is a schematic diagram of a single one of the 10 identical circuits that controls a motor. 
     FIG. 11A is a front view of the overall layout which, for clarity, does not show the tube, vertical moving, whirler, and finger assemblies or the winch, monitor, and circuit boards. FIG. 11B, for clarity, does not show the grabber, breaker, hooker, or tie support assemblies. 
     FIGS. 12A-12S are a series of schematic diagrams of the various stages of the formation of the tie knot. Some of the elements of some of the assemblies forming the knot are shown. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     I. Mechanisms: 
     (1) The tube assembly and vertically moving assembly—(FIGS. 1A-1C, FIG. 2) 
     The rotating tube  1  is approximately 3.5 inches in diameter, and 4 inches in length. It has a 2 inch long tab  2  attached to the periphery of its left end which is raised about ¼ inch above the surface. The tab  2  is secured at its left end, extends rightwards and is open at its right end. To the left of the tab  2 , a timing belt  3  is bonded to the periphery of the rotating tube  1  and flanges  17  are provided. This bonded belt acts as a timing belt pulley wheel and engages a moving timing belt  4  that causes the rotating tube to rotate about an inner concentric support tube  5  which acts as a bearing surface. The support tube in turn is attached by a connecting bracket  6  to a vertically moving assembly  7  that, via a cable  19  and top pulley  9 , is moved upwards by a winch drum and motor  10 , and downwards by gravity—as allowed by the winch unwinding. The timing belt  4  is driven by a motor  11  and attached timing belt pulley  18  mounted on the connecting bracket  6 . The vertically moving assembly  7  moves on a vertical post  8  fixed to a heavy baseplate  12 . An additional vertical guide rod  13  combined with a slotted bracket  14  attached to the vertically moving assembly  7  prevents yaw motions of the rotating tube  1 . Additionally, the inside  15  and outside  16  cylindrical surfaces of the support tube are lined with Teflon tape to reduce friction of the tie being pulled through the support tube, as well as friction between the rotating tube  1  and the support tube  5 . A special provision is made to insure that the turns of cable  19  on the winch drum  10  never overlap in order to insure vertical accuracy. This is accomplished by feeding cable  19  leading to winch drum  10  through a vertical hole in guide  20  which moves laterally (into and out of the paper in FIG. 2) on pin  20   a  as vertically moving assembly  7  is moved up and down. This lateral motion occurs because an additional cable  21  at a slight angle to the vertical is also fed through the vertical hole in guide  20   
     (2) The hooker assembly—(FIGS. 3A-3B) 
     The horizontally oriented hooker  21  is made of a coathanger wire which at its right end has 90 degree bend containing a 2 inch long section and another 90 degree bend of ¼ inch to form a modified “U” of disparate leg lengths suitable for hooking a slender object. Hooker wire  21  is attached to the shaft of a motor  22  which is mounted on a block  23  containing linear bearings  24  that allow it to translate horizontally along two guide rods  25  supported in a U shaped mounting block  32  that is attached to a vertical post  33  attached to the baseplate  12 . The motor is pushed and pulled horizontally by a linkage  26  attached to the pedal  27  of a bicycle crank with integral sprocket wheel  28  which in turn is rotated by a bicycle chain  29  which is driven by sprocket wheel  30  attached to electric motor  31  also mounted on post  33 . This means of producing a horizontal translation is the reverse of the usual reciprocating to rotary conversion of motion such as was done in a railroad steam engine and is used for aesthetic purposes. In reality a rack and pinion or a leadscrew arrangement would have been more efficient but less pleasing to the eye. 
     (3) The whirler assembly—(FIGS. 4A-4B) 
     Whirler  34  is a multiply bent plastic piece, of the shape shown in FIG. 4, which has 1 inch diameter rod  35  at its distal end to catch RT when it rapidly sweeps RT around the rotating tube  1 . Rod  35  needs to be roughened to increase the friction coefficient so that the RT does not slip off during the whirling motion. Forward projection  36  of the end of whirler  34  allows it to push the RT through the Vee (see FIG. 12 c ) formed by the LT and RT hanging from the tie support assembly (see FIG. 8 b ), and let it fall forward of rotary tube  1 . Whirler  34  is attached to the shaft of motor  37  mounted by bracket  39  to vertical post  38  secured to baseplate  12 . 
     (4) The finger assembly—(FIGS. 5A-5B) 
     Finger  40  consists of lever  41  and oblique projection  42  coming off it several inches from its extremity. Lever  41  is attached to the shaft of a first motor  43  held by a bracket  44  attached to a second motor  45  whose shaft  46  is clamped stationary to bracket  47  mounted on vertical post  38 . Shaft  46  is oriented horizontally and is perpendicular to the direction of translation of hooker wire  21 . Thus when motor  45  is powered, both motors  43  and  45  rotate in roll which alters the plane of motion of lever  40 . When motor  43  is powered, lever  40  rotates so that it moves towards the front or rear surface of the rotating tube  1 . 
     (5) The grabber assembly—(FIGS. 6A-6B) 
     The grabber contains lever  48  attached to motor  49  whose rotation changes the elevation angle of lever  48 . The extremity of lever  48  contains an anvil bracket  49   a . Attached partway up lever  48  is a second electric motor  50 , with its axis parallel to that of motor  49 , which rotates bar  51  whose extremity has an attached grabber jaw fixture  52  that mates with and pushes against anvil  49   a  to form a clamp. Both clamping surfaces of  52  and  49   a  are lined with a high friction material  53  (e.g. urethane class ML6 high friction material, Meridian Laboratory, Middleton, Wis.) to facilitate clamping the LT or RT even if only a small portion is engaged. Elevation motor  49  is mounted on bracket  50   a  secured to baseplate  12 . 
     (6) The breaker assembly—(FIG. 7) 
     The breaker consists of sturdy lever  54  attached to timing belt pulley wheel  55  which rotates on shaft  56  mounted in vertical post  57  attached to baseplate  12 . Pulley wheel  55  is rotated by electric motor  58  via several timing belts  59 ,  60  and pulleys  61 ,  62 ,  63 , arranged to provide a mechanical advantage. The distal end of lever  54  contains short rod  64  at right angles to lever  54  which engages the main loop of the completed tie, where the neck would normally be, when Lever  54  is rotated about shaft  56 . Electric motor  58  is mounted on vertical post  57  by bracket  65 . The shaft  66  upon which are mounted pulley wheels  61  and  63  is supported by a bearing block  67  which is contacted by two tension screws  68 . The tension screws  68  are mounted in a block  69  fastened to post  57  at a position such that the two belts  59 , and  60  can be tightened to the desired tension when the tension screws  68  are advanced against the bearing block  67 . Bearing block  67  is supported by a swinging bracket  70  that is hinged to vertical post  57  by a pin  71 . 
     (7) The tie support—(FIGS. 8A-8B) 
     Near the middle of its length, a portion of the tie  77  is secured to a horizontal support piece  72  attached to vertical post  38 . This portion  77  is clamped in place between horizontal support  72  and front bar  73  so that the RT and LT hang straight down. The supported ends of the RT and LT are laterally positioned and separated by means of bottom guides  74  and top guides  75 , to locate RT and LT relative to the whirler, finger and hooker assemblies. Hinge pin  76  allows front bar  73  to be swung away from horizontal support piece  72  when locking knob  76  is unscrewed. This provides for initially loading and removing the tie  77  before or after the tying cycle, and, if desired, for removing the tie  77  at any time during the cycle (if the machine is stopped) e.g. when the knot is complete so it can be put on someone without disrupting the tied knot. Top guides  75  are rounded to avoid damaging tie  77  in the vicinity of where it is clamped. 
     (8) The electronic circuitry—(FIGS. 9-10) 
     Data from personal computer  78  comes into interface board  79  via printer port cable  80 . Two digital numbers are transmitted: the motor number and how far that motor should rotate. The motor number is converted into a logic enable signal on one of 10 lines  81 , each leading to a different sample and hold (S/H) module  82 . The second digital number is converted by a digital to analog converter into an analog voltage command  83  that is connected to the analog input terminal  84  of all 10 of S/H&#39;s  82 . All of the S/H modules  82  ignore the analog input voltage  83  except for the one S/H module  82  that has been selected by the logic enable voltage  81  (that was determined by the first digital number). The output  85  of each S/H  82  is the command voltage  85  fed through a resister Rin into the input  85   a  of each separate power amplifier  86  whose output  92  in turn is connected to a different one of the 10 electric motors  87  (FIG.  10 ). The output  93  from each electric motor shaft potentiometer  88  is fed back through a resister Rin to the input  85   a  of amplifier  86  that drives the motor attached to that potentiometer via a buffer amplifier  89 . Each power amplifier  86  has a feedback resistor Rf between its output  92  and its input  85   a  as is standard practice by electronic engineers so that at input  85   a  to each power amplifier  86  the potentiometer output is subtracted from S/H output  85  resulting in a feedback servomechanism in which a given voltage command corresponds to a given shaft angle—as is well known by feedback control engineers. To minimize extraneous voltages and grounding problems, the power return from the motors goes to a power ground,  102 , which is kept separate from the ground  94  for the low level voltage signals as is customary practice. 
     Thus as the different pairs of numbers are sequentially read out, different S/H modules  82  are controlled which in turn makes the corresponding motors move through shaft angles that correspond to the command voltages. The computer  78  runs a program which reads out the two numbers to the printer port and then, according to a third parameter in the data set of numbers, the computer waits a prescribed amount of time before reading out the next pair of numbers. Different data sets correspond to different sequences of moves of the various actuators described above so as to tie and untie the necktie. Thus the data set is what determines how the different parts move. The  10  S/H  82  modules,  10  power amplifiers  86  and feedback connections  93  and motor output connections  92  are contained on two separate circuit boards  90 ,  91 . These and the interface board  79  are visibly mounted to a vertical post  100  secured to the baseplate  12  in a pleasing inverted Y configuration  101 . 
     (9) Overall Layout—(FIGS. 11A-11B) 
     Baseplate  12  is mounted on top of dull black plywood base  95  with 4 casters  96  and side shelf  97  for the computer keyboard and mouse. Computer  78  is located out of sight inside base  95 . Attached to the rear of base,  95  is vertical post  98  that supports color flat panel computer monitor  99  that continually displays the command data set as the different parts move using a separate color for each different motor. The relative placement of the different actuators described in  1  thru  8  above is shown in FIG.  11 . 
     II. Method of Operation—(FIGS.  12 -A- 12 S) 
     At the beginning of the cycle, both RT and LT hang straight down from tie support  72 , 73 , and rotary tube  1  is at the lower end of its travel—6 inches above the end of RT. The first part of the cycle uses finger  40  to manipulate the end of the RT so that it is caught in tab  2 , no matter how it might previously have been hanging (e.g. at startup) (FIG. 12 a ). Rotary tube  1  is then raised until it is about ¾ of the way up to tie support  72 , 73 . Rotary tube  1  is also rotated part of a turn, and because RT is captured in tab 2, 6 inches above its end, the 6 inch free end of the RT hangs down from one side of tab  2  while on the other side of tab  2  RT is partially wrapped around rotary tube  1  creating a loop of RT hanging down from rotary tube  1  (FIG. 12 b ). With the prior assistance of finger  40 , the LT is drawn through this loop of RT (FIGS. 12 b,c ) by hooker  21 . The front of the loop is next moved to the rear of rotary tube  1  by finger  40  so that a very loose first wrap of RT around LT is created which is located outside of and behind rotary tube  1  (FIG. 12 c ). This creates a Vee space between the RT and LT where they hang down from Tie Support  72 , 73 . By a series of back and forth rotations of rotary tube  1 , the slack of the first wrap is removed so that RT is wrapped tightly around LT (FIG. 12 d ). This slack removal, which is crucial, results from the interaction of the friction characteristics of the tie and rotary tube  1  and its tab  2  with the weight of the hanging tie suspended from rotary tube  1 . When the tube  1  with tab  2  rotates in the forward direction it drags the tie with it, but when it rotates in the reverse direction there is slippage between the RT and rotary tube  1  which takes up the slack. 
     Next, using finger  40 , the free hanging end of RT is manipulated laterally along rotary tube  1  to a position centered under the Vee space (FIG. 12 e ). Then the specially shaped whirler  34 ,  35  rotates about its horizontal axis to intercept the hanging RT and carry it around rotary tube  1  and thru the Vee space (FIGS. 12 f,g ). This is equivalent to manually bringing the RT up from under after the second crossover of the four-in-hand tie knot. It is the second wrap plus the end of RT hanging for 6 inches over the front of rotary tube  1 . RT is now manipulated to the right end of the rotary tube  1  and its support tube  5  by finger  40  (FIG. 12 h ), and hooker  21  is moved through support tube  5 , rotated about its axis in order to intercept the length of RT about 6 inches from its end (FIG. 12 i ), and, finally, hooker  21  pulls RT through support tube  5  (FIG. 12 j ). At this point topologically speaking, the knot has been formed. 
     The next process is to scrape the second wrap off of the rotating tube  1  using finger  40 , and hooker  21  in a pushing rather than pulling mode (FIG. 12 k ). Rotary tube  1  is then lowered out of the way and the loosely configured knot hangs free with the ends of the LT and RT protruding from the loops of the knot (FIG.  121 ). The LT is then secured by hooker  21  in order to position the hanging end of the RT in a favorable location so that the RT can be grabbed by grabber jaws  49   a ,  52  and sequentially pulled in a series of moves to tighten the knot (FIG. 12 m ). After each pull RT is released by grabber jaws  49   a ,  52  and repositioned so that the they can subsequently clamp RT closer to the knot and then RT is pulled again. After multiple pulls (e.g. four) the RT is then released and the LT is secured by grabber jaws  49   a ,  52  (FIG. 12 n ) and pulled tight to shape the knot so that it looks as if it had been tied by a human (FIG. 12 o ). The knot is then pulled apart by breaker lever  54  which is moved into the large loop where a persons neck would normally reside (FIG. 12 p ), and this loop is pulled until the LT is pulled through the knot which as a result comes apart. To facilitate this, the RT is first secured by grabber jaws  49   a ,  52  (FIG. 12 r ) with the aid of hooker  21  (FIGS. 12 p,q,r ) and held at an oblique angle which reduces the friction of the LT being pulled through the knot (FIG. 12 r ). The resulting twisted free hanging RT (FIG. 12 s ), is then swung back and forth in a variety of ways by finger  40  to remove all twists and turns so it hangs straight and it is then manipulated by finger  40  so it is caught in tab  2  on rotating tube  1 , thus returning the tie to its original position (FIG. 12 a ). All the motors return to their initial positions completing the cycle.