Abstract:
An apparatus is disclosed for enhancing the operational performance of a servo. The apparatus comprises an auxiliary shaft that is independent and displaced from the servo and an actuation sensor that is operably coupled to the auxiliary shaft. The auxiliary shaft is configured to be driven by a motor associated with the servo.

Description:
The present application is a continuation of, and is based on, and claims the benefit of U.S. patent application Ser. No. 11/153,800, filed on Jun. 15, 2005, the content of which is hereby incorporated by reference in its entirety, the latter application being based on U.S. provisional application 60/584,288, filed on Jun. 30, 2004. 
    
    
     BACKGROUND 
     The present invention generally pertains to the hobby-mechanical industry. More specifically, the present invention pertains to means for extending the torque and/or rotational capacity of a hobby servo. 
     A servo motor (a.k.a. simply a “servo”) is a device having a rotatable output shaft. The output shaft can typically be positioned to specific angular positions in accordance with a coded signal received by the servo. It is common that a particular angular position will be maintained as long as a corresponding coded signal exists on an input line. If the coded signal changes, the angular position of the shaft will change accordingly. Control circuits and a potentiometer are typically included within the servo motor casing and are functionally connected to the output shaft. Through the potentiometer (e.g., a variable resistor), the control circuitry is able to monitor the angle of the output shaft. If the shaft is at the correct angle, the motor actuates no further changes. If the shaft is not at the correct angle, the motor is actuated in an appropriate direction until the angle is correct. 
     There are different types of servo motors that include output shafts having varying rotational and torque capabilities. For example, the rotational and/or torque capability of an industrial servo is typically less restricted than that of a hobby servo. That being said, hobby servos are generally available commercially at a cost that is much less than that associated with industrial servos. 
     Because hobby servos are relatively small and inexpensive, they are popular within the hobby-mechanical industry for applications such as, but by no means limited to, hobby robotic applications and radio-controlled models (cars, planes, boats, etc.). One example of a hobby servo is the Futaba S-148 available from Futaba Corporation of America located in Schaumburg, Ill. 
     The output shaft of a hobby servo is typically capable of traveling approximately 180° (possibly up to 210° or more depending on manufacturer). Rotation of the hobby servo shaft is limited typically by one or more internal mechanical stops. It is also typically true that the output shaft of a hobby servo is capable of producing a relatively limited amount of torque power. The torque and rotational limitations of a hobby servo are adequate for many hobby applications, such as model car steering control, puppet control, robot arm or head movement and/or model airplane rudder control. It is true, however, that some applications require a servo having torque power and/or a rotational capacity that is beyond the capability of a typical hobby servo. Increased torque power and/or rotational capacity enable greater mechanical flexibility. 
     Some hobby servos can be mechanically altered to provide an extended range of rotation. However, this solution requires mechanical alteration that often only works for some types of servos. Rotational control for most hobby servos is limited by the internal potentiometer being utilized to monitor rotation. When a hobby servo is hacked to extend the rotational capacity, the internal potentiometer of the servo will, in most instances, not be configured to monitor angular positions too far beyond the original range of rotation. The control system of a hacked servo will commonly not be configured to accurately position the servo output shaft too far within the extended range of rotation. For this reason, it becomes difficult to control rotation once a hobby servo has been adapted for extended rotation. 
     SUMMARY 
     Embodiments of an independent and modular apparatus are disclosed for enhancing the operational performance of a servo motor. Embodiments include a frame member having a servo motor and a rotatable shaft mounted therein. The output shaft of the servo motor and the rotatable shaft are displaced from one another. Means are incorporated for translating rotational motion from the output shaft to the rotatable shaft so as to enable a torque or rotational capacity for the rotatable shaft that is greater than that of the servo output shaft. Further means are incorporated to enable proportional control of the rotatable shaft even when the output shaft of the servo is rotated beyond its intended range of rotation and/or torque. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a side view of a hobby servo. 
         FIG. 2  is a side and front view of an enhancement gear. 
         FIG. 3  is a side view of the enhancement gear after being engaged to the hobby servo. 
         FIG. 4  is a top perspective view of an enhancement sprocket. 
         FIG. 5  is a top perspective view of an apparatus for extending the torque capacity of a hobby servo motor. 
         FIG. 6  is a top perspective view of an apparatus for extending the rotational capacity of a hobby servo motor. 
         FIG. 7  is a side perspective view of an apparatus for extending the rotational capacity of a hobby servo motor. 
         FIG. 8A  is a front perspective view of an apparatus for extending the operational capacity of a servo motor. 
         FIG. 8B  is a back perspective view of the apparatus of  FIG. 8A . 
         FIGS. 9A-9K  are diagrammatic illustrations demonstrating alteration of a hobby servo motor. 
         FIGS. 10A ,  10 B,  11 , and  12 A- 12 K are diagrammatic illustrations demonstrating construction of an apparatus for extending the operational capacity of a servo motor. 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  is a side view of a hobby servo  100 . Servo  100  includes attachment flanges  104 . Flanges  104  typically include apertures formed therein for receiving an attachment mechanism (e.g., a screw, bolt, etc). The attachment mechanism is utilized to secure servo  100  within an operative environment. Servo  100  also includes an electrical connection  106  that enables the servo to receive electrical power and/or control signals. 
     Servo  100  includes a rotatable output shaft  102  also known as a servo spline. The servo output shaft  102  can be positioned to specific angular positions in accordance with a coded signal received by the servo. It is common that a particular angular position will be maintained as long as a corresponding coded signal exists on an input line. If the coded signal changes, the angular position of the servo output shaft  102  will change accordingly. Control circuits and a potentiometer are typically included within the illustrated outer housing of servo motor  100 . The control circuits and potentiometer are functionally connected to the servo output shaft  102 . Through the potentiometer (e.g., a variable resistor), the control circuitry is able to monitor the angle of the output shaft. If the shaft is at the correct angle, the motor actuates no further changes. If the shaft is not at the correct angle, the motor is actuated in an appropriate direction until the angle is correct. 
     Rotation of servo output shaft  102  is typically limited to around 180°. In most cases, rotation is limited at least because of an internal mechanical stop. It is also common that servo output shaft  102  is capable of producing a relatively limited amount of torque power. The torque and rotational limitations of a hobby servo are adequate for many applications; however, some applications require a servo having torque power and/or a rotational capacity that is beyond the capability of a typical hobby servo. Increased torque power and/or rotational capacity enable greater mechanical flexibility. 
       FIG. 2 , in accordance with one aspect of the present invention, is a side and front view of a servo enhancement gear  150 . Servo gear  150  includes a plurality of gear teeth  152  disposed around an outer edge perimeter of gear  150 . A female spline receiver  154  is formed through the approximate middle of the gear. Spline receiver  154  is, illustratively, an aperture having a series of teeth formed around the outer perimeter. The teeth formed within spline receiver  154  are illustratively configured to engage a corresponding set of teeth formed on servo spline  102 . It is common for servo spline  102  to have a 23, 24 or 25 tooth configuration. In accordance with one aspect of the present invention, a different gear  150  can be utilized depending upon which spline receiver  154  configuration is needed to accommodate a given spline  102 . In accordance with another embodiment, a specialized spline receiver  154  configuration for a gear  150  is configured to accommodate attachment to multiple spline  102  configurations. It should be noted that spline receiver  154  configurations other than those suitable for 23, 24 or 25 tooth configurations are within the scope of the present invention. 
       FIG. 3 , in accordance with one aspect of the present invention, is an illustration of a servo enhancement gear  150  that has been attached to a servo  100 . Spline receiver  154  is engaged to spline  102 . A washer  158  and a screw  160  are utilized to secure gear  150  to spline  102 . In one embodiment, washer  158  has an overall diameter that is greater than spline receiver  154 . Accordingly, the washer is centered on the outside face of gear  150  such that the aperture in the washer corresponds to an attachment aperture formed in spline  102 . Screw  160  is then engaged into the attachment aperture in spline  102  until washer  158  tightens against gear  150  thereby locking gear  150  into a rotational engagement with spline  102 . Of course, other attachment schemes are within the scope of the present invention. 
     In accordance with one aspect of the present invention, gear  150  is configured such that the surface around spline receiver  154  will engage a surface proximate spline  102  in a flush manner. For example, with reference to  FIG. 1 , servo  100  includes a relatively planar surface  108 . Similarly, with reference to  FIG. 2 , gear  150  includes a relatively planar surface  156 . As is shown in  FIG. 3 , when gear  150  is engaged to servo  100 , surfaces  108  and  156  are engaged to one another in a relatively flush relationship. 
     In accordance with one aspect of the present invention, a rotational mechanism other than a gear is attached to servo spline  102  in a manner substantially similar to the attachment scheme shown and described in relation to  FIGS. 1-3 .  FIG. 4  is a perspective view of a sprocket  400 . Sprocket  400  includes a plurality of teeth  452  disposed around an outer perimeter of sprocket  400 . A chain  456  is in engagement with a substantial number of teeth  452 . A hub  458  is located within the center of sprocket  400  and is supported by a plurality of spokes  460 . Hub  458  includes a spline receiver  454 . Spline receiver  454  is illustratively similar to spline receiver  154  ( FIG. 2 ) in that it is configured to engage a standard hobby servo output spline  102  ( FIG. 1 ). Different versions of sprocket  400  can be selected and/or created to accommodate different servo splines  102 . A sprocket  400  having a spline receiver  454  configured to receive a 23, 24, 25 tooth or any other output spline configuration is within the scope of the present invention. 
     Engagement of a sprocket  400  to a servo motor  100  is illustratively similar to the engagement schemes described in relation to  FIGS. 1-3 . Spline receiver  454  is engaged to spline  102 . In accordance with one embodiment, a washer/screw arrangement is utilized to secure the sprocket to the servo as was previously described. In accordance with another embodiment, however, the outside portion of hub  458  (opposite the side where the servo spline is inserted) is configured such that the spline receiver  154  aperture is closed but for an opening large enough for insertion of an attachment mechanism (i.e., a screw). In this case, a washer is not necessary because a screw can be inserted through the aperture and into the engagement with the servo spline  102 . As a screw is tightened into engagement with the servo spline  102 , the head of the screw will engage the sprocket hub and secure the sprocket to the servo (i.e., secure the servo spline within hub  458 ). 
     In accordance with one aspect of the present invention, hub  458  of sprocket  400  is configured such that a surface of the sprocket will flushly engage a surface of the servo motor when the motor and sprocket are functionally engaged to one another. As is shown in  FIG. 4 , an annular lip  480  is formed on the inside of hub  458  to enable a flush engagement with surface  108  illustrated in  FIG. 1 . 
     In accordance with one aspect of the present invention, any rotational device can be attached to a servo output shaft in a manner as described herein in the context of a gear and a sprocket. Once attached to the servo output shaft, the item will generally rotate when the output shaft rotates. Accordingly, the rotation of the item will be limited just as is the rotation of the output shaft. 
     As was mentioned above, some mechanical applications require a servo having a range of rotation greater than the range typically associated with a hobby servo. Also, some mechanical applications require a servo having greater torque power than that typically associated with a hobby servo. The present invention pertains to simple and inexpensive enhancements for hobby servos that are capable of enabling a greater range of rotation, or a greater range of torque power, than typically associated with a hobby servo without sacrificing proportional control characteristics. 
     Accordingly, a gear, sprocket or any other rotational mechanism can be secured to the output shaft of a hobby servo. In accordance with one aspect of the present invention, the hobby servo can then be mounted in a frame and configured to translate rotational motion to a shaft that is rotatably mounted within the same frame. The shaft will then be configured for a torque and/or rotational capacity that is greater than the output shaft of the servo itself. 
       FIG. 5  is a perspective view of an apparatus  500  for extending the operational capacity of a servo motor  502 . Servo  502  is secured within frame  504 . For example, frame  504  illustratively includes apertures formed therein and configured to receive an attachment mechanism (e.g., a screw, bolt, etc). In one embodiment, apertures formed in frame  504  are configured to line up with apertures formed in attachment flanges  104  ( FIG. 1 ). An attachment mechanism can then be inserted through the apertures in flanges  104  that are lined up with corresponding apertures in frame  504 . In this way, the servo can be secured to the frame. Within  FIG. 5 , screws  522  are illustrated. These screws illustratively are inserted through apertures in a flange  104 , and through corresponding apertures formed in the frame. A bolt can then be engaged to the ends of the screws  522  so as to secure a flange  104  to the frame  504 . A gear  550  is attached to the output spline of servo motor  502  with a screw  160  and a washer  158  as described in relation to  FIGS. 1-3  (another attachment scheme such as the non-washer scheme described in relation to sprocket  400  in  FIG. 4  could alternatively be utilized). Gear  550  is illustratively similar to gear  150  ( FIG. 2 ) only smaller. Servo  502  is illustratively similar to servo  100 . The servo output shaft illustratively has a limited capacity for rotation (e.g., around 180°). 
     An auxiliary shaft  542  is rotatably mounted in frame  504  and is displaced from servo  502 . An auxiliary gear  544  is attached to auxiliary shaft  542  and engaged via gear teeth to gear  550 . Again, gear  550  is attached to the output shaft of servo  502 . Accordingly, when the output shaft of servo  502  is caused to rotate, gear  550  causes that rotation to be translated to auxiliary gear  544 , and therefore to auxiliary shaft  542 . Because gear  550  is considerably smaller than auxiliary gear  544 , the torque associated with auxiliary shaft  542  will be much greater than the torque of the servo motor output shaft. The expanded torque associated with shaft  542  can then be configured to actuate a mechanical load. For example, an item can be attached to auxiliary shaft  542  (or attached to gear  544 ) and utilized to mechanically take advantage of the expanded torque. 
     In accordance with another embodiment, auxiliary gear  544  has a diameter that is much less than the diameter of gear  550 . Accordingly, when gear  550  is attached to a hobby servo output shaft, and when gear  544  is attached to an auxiliary shaft, then auxiliary shaft  542  will produce a range of rotation that is greater than that generated by the output shaft of the hobby servo. 
       FIG. 6  is a top perspective view of an apparatus  600  for extending the operational capacity of a servo motor.  FIG. 6  shows a hobby servo  602  mounted within a frame  604 . Servo  602  is illustratively similar to servo  502 . Similar to the  FIG. 5  configuration, auxiliary shaft  642  is rotatably mounted within frame  604  and is displaced from hobby servo  602 . A chain  656  is engaged to teeth  652  of an enhancement sprocket  650 . An auxiliary gear  644  is attached to auxiliary shaft  642 . Illustratively, enhancement sprocket  650  can be attached to the output shaft of hobby servo  602  as was described in relation to  FIG. 4 . Chain  656  illustratively stays engaged to teeth  652  while chain  656  becomes engaged to auxiliary gear  644 . Accordingly, when the output shaft of hobby servo  602  is caused to rotate, chain  656  causes that rotation to be translated to auxiliary gear  644  and therefore to auxiliary shaft  642 . Because enhancement sprocket  650  is considerably larger than auxiliary sprocket  644 , the rotation of auxiliary shaft  642  will be much greater than the rotation of the output shaft of hobby servo  602  and much greater than the overall rotation of enhancement sprocket  650 . The expanded rotation of auxiliary shaft  642  can then be configured to actuate a mechanical load. For example, a mechanical item can be attached to auxiliary shaft  642  and utilized to mechanically take advantage of the expanded rotational motion. 
     In accordance with one embodiment, enhancement sprocket  650  has a diameter that is much less than the diameter of the corresponding auxiliary gear  644 . Accordingly, when enhancement sprocket  650  is attached to a hobby servo output shaft, and when auxiliary gear  644  is attached to an auxiliary shaft, and when chain  656  is in place, then auxiliary shaft  642  will produce a torque power that is greater than that generated by the output shaft of the hobby servo. 
     In accordance with another embodiment, a belt design can be utilized rather than a chain design. For example, enhancement sprocket  650  and auxiliary gear  644  can be configured to accommodate a belt rather than a chain. Accordingly, as the output shaft rotates and causes enhancement sprocket  650  to rotate, a frictionally engaged belt moves around the outside diameter of the enhancement sprocket as well as around the outside diameter of the auxiliary gear, such that rotational motion is translated from the output shaft to the auxiliary shaft. When a belt is utilized, enhancement sprocket  650  and auxiliary gear  644  need not necessarily have gear teeth. 
     As was described in relation to  FIG. 5 , in accordance with another aspect of the present invention, neither a belt nor a chain is utilized. Instead, enhancement sprocket  650  and auxiliary gear  644  are directly geared to one another. The enhancement sprocket  650  is secured to the output shaft of the hobby servo  602  as discussed in relation to  FIGS. 1-3 . The enhancement sprocket  650  is directly and operably engaged to auxiliary gear  644 . Auxiliary gear  644  is configured to translate rotational motion to auxiliary shaft  642 . 
       FIG. 7  is a side perspective view of the apparatus  600  previously illustrated and described in relation to  FIG. 6 . The view shown in  FIG. 7  demonstrates how frame  604  is constructed. Frame  604  includes apertures  730  for receiving an attachment mechanism (e.g., a screw, bolt, etc) for attaching apparatus  600  within an operational environment. For example, the frame could be secured in a location proximate to a target for mechanical actuation. The frame member includes a first aperture  732  for receiving and supporting servo  602 . A second aperture  722  is also formed in the frame and is configured to receive and support auxiliary shaft  642 . 
     Attachment apertures  740  are formed in the frame as necessary to accommodate attachment of servo  602  to the frame (e.g., attachment flanges associated with the servo have apertures that are lined up with the attachment apertures  740  within the frame . . . and an attachment mechanism is slid through the aligned apertures to secure the servo to the frame). 
     Frame  604  includes a first panel portion  734  that is displaced from but connected to a second panel portion  736 . A displacement mechanism  738  is positioned between panels  734  and  736 . In fact, several displacement portions  738  are utilized to space and support the panel portions relative to one another. Each displacement mechanism  738  is illustratively attached to the first and second panel portions. For example, an attachment mechanism (e.g., a screw, an adhesive, etc) is utilized to secure the displacement mechanisms  738  between the panel portions. In one embodiment, a screw is inserted through an aperture in a panel portion and into the displacement portion  738 . The screw can extend all the way through the displacement portion  738  and through a corresponding aperture formed in the opposite panel portion, wherein a bolt is then utilized to secure the panel portions to the displacement mechanism. Alternatively, a single screw can be inserted through each end of the displacement mechanism through an aperture formed in the panel portion such that the screws engage and secure themselves to the inside of the displacement portion thereby securing the panel portions to the displacement portion. 
       FIGS. 8A and 8B , in accordance with one aspect of the present invention, are front and back views, respectively, of a different apparatus  800  for extending the operational capacity of a servo motor. Apparatus  800  is similar in many aspects to embodiments previously illustrated and described herein. Hobby servo  802  and auxiliary shaft  842  are mounted within frame  804 . Auxiliary gear  844  is attached to auxiliary shaft  842  and is rotatably coupled to servo motor gear  850  in a manner similar to that illustrated in  FIGS. 3-6 . For example, means such as a directed engagement, shown in  FIG. 5 , or a chain, shown in  FIGS. 4 and 6 , or any other means may be used to translate rotation from the servo output shaft to auxiliary gear  844  and shaft  842 . In accordance with the illustrated embodiment, apparatus  800  is configured in a torque enhancement configuration (an enhanced rotation configuration may alternatively be implemented). In the illustrated configuration, gear  850  has a diameter much less than the diameter of auxiliary gear  844 . As a result, the torque capacity associated with auxiliary shaft  842  will be greater than the torque capacity of the servo motor gear  850 . The expanded torque capacity associated with shaft  842  can be taken advantage of to actuate increased mechanical loads. For example, an item can be attached to auxiliary shaft  842  (or to gear  844 ) and utilized to mechanically take advantage of the expanded torque capacity. 
     Another result of the illustrated configuration, however, is that auxiliary gear  844  will have an angular rotational range which is even less than the standard angular rotational range of hobby servo gear  850 . Most hobby servos have a predetermined rotational range of approximately 180°. The illustrated auxiliary gear  844  will have a rotational range of even less than 180°. For certain applications, expanded torque is needed without sacrificing rotational range. 
     In accordance with another aspect of the present invention, hobby servo  802  is internally modified to enable a range of output shaft rotation that is greater than its “off-the-shelf” capability. For example, in accordance with one embodiment, an internal mechanical stopping mechanism, which prevents rotation past a predetermined angle, is removed from hobby servo  802  to enable for continuous rotation in either direction. As a result of the modification, servo  802  can rotate auxiliary gear  844  beyond the range of rotation attributed to the gear prior to the servo modification. 
     Following modification of servo  802 , limitations inherent to the internal potentiometer make it a poor choice for subsequent control functionality. As previously mentioned, in a normal servo operating configuration, the servo motor rotates the servo output shaft corresponding to the coded signal received by the servo. The output shaft is rotated until the signal from the internal potentiometer of the servo, which corresponds to the angular position of the servo output shaft, matches the coded signal received by the servo. Most hobby servos contain internal potentiometers that are physically limited to monitoring a limited range of angles (e.g., often less than 200 degrees). Therefore, when apparatus  800  is configured in the illustrated enhanced torque configuration and incorporates a servo  802  modified for extended rotation, the internal potentiometer is not the best control component for applications that require the servo shaft to rotate beyond the typical rotation limits in order to provide shaft  842  with an improved rotational capacity. The internal potentiometer is not likely to support control of a range of rotation for shaft  842  that is even equivalent to the original rotational range of the servo output shaft. Therefore, in accordance with one aspect of the present invention, the internal potentiometer is disconnected and an auxiliary potentiometer  880  is asserted into the control scheme. Potentiometer  880  is functionally connected to shaft  842  and facilitates the proportional control thereof. 
     Accordingly, as was mentioned above, some applications require increased (enhanced) torque while still demanding the same, or in some cases greater, rotational capacity. Therefore, in accordance with one aspect of the present invention, the external potentiometer  880  is attached to auxiliary shaft  842  and is utilized to control the rotation of auxiliary shaft  842 . As a result, servo  802  utilizes the coded input signal and the signal from external potentiometer  880  to rotate and position auxiliary shaft  842 . A particular external potentiometer  880  having any of a variety of control characteristics can be selected and implemented based on the requirements of a given application. Therefore, a potentiometer with a rotational range of substantially less than or greater than 180° can be selected and implemented as desired. 
     In accordance with one embodiment, apparatus  800  is configured in an extended rotation configuration. In this configuration, as previously mentioned, servo gear  850  has a diameter substantially greater than auxiliary gear  844 . Further, in accordance with this embodiment, external potentiometer  880  is configured to provide rotational and/or position control over the extended range of rotation of auxiliary shaft  842 . 
     In accordance with one aspect of the present invention,  FIGS. 9A-9K  are diagrammatic illustrations demonstrating alteration of a hobby servo including removal of rotation impediments and disconnection of the internal potentiometer. While many types and brands of hobby servos can be modified in a manner similar to the processes described herein,  FIGS. 9A-9K  are directed to the removal of mechanical stops from a Hitec HS-645MG hobby servo available from Hitec RCD USA, Inc. located in Poway, Calif. 
     In accordance with  FIG. 9A , screws are removed from the bottom of the servo  802  and the top gear case (not pictured) is removed to expose the drive gears. The second to last drive gear  910  is removed first, followed by the main spline (gear with shaft) gear  912  as illustrated in  FIG. 9B . Further, the bushing or bearing  914  is removed from the spline gear  912  (also as pictured in  FIG. 9B ). Not all servos have a bushing or bearing. In some cases, the outer gear case cover is configured to serve as a bushing. The bottom case (not pictured) is removed from the servo  802  and the electronics  916  and the potentiometer  918  are removed as illustrated in  FIG. 9C . With the spline gear  912  out, pliers are used to remove the small pin stop  920  as shown in  FIG. 9D  (care must be exercised as to not damage the teeth on the gear). A utility knife is used to trim the case (make a groove  922 ) as illustrated in  FIG. 9E  to allow for extra wires that will be required to enter into the case when an auxiliary potentiometer is subsequently installed. 
     Wires  924  are disconnected from the internal potentiometer  918  using a soldering iron, while making note of the position of each colored wire  924  as different servos incorporate different colors and configurations (i.e. white=left, yellow=center, red=right) (shown in  FIG. 9F ). The electronics  916  and potentiometer  918  are put back in the case  908 , illustrated in  FIG. 9G , with the potentiometer wires  924  running through the groove  922  (created by the step shown in  FIG. 9E ). The bottom case  906  is replaced to cover the electronics  916  ( FIG. 9H ) and the gears are reassembled back in place ( FIG. 9I ). The bearing or bushing  914  is placed back on the main spline gear  912  and the top gear case  904  is placed back on the servo ( FIG. 9J ). The screws are replaced in the bottom of the servo and the pinion gear  950  is mounted onto the servo output shaft using a washer  952  and servo horn screw  954  ( FIG. 9K ). Pinion gear  950  is functionally similar to servo output gear  850  referenced to apparatus  800  in  FIG. 8 . 
     In accordance with one aspect of the present invention,  FIGS. 10A ,  10 B,  11 , and  12 A- 12 K are diagrammatic illustrations demonstrating the construction of apparatus  800  and the connection of external potentiometer  880 .  FIG. 10A  is a diagrammatic illustration demonstrating an illustrative layout of a top mounting plate  876  of apparatus  800 . Plate  876  has a length  1014  of 3.907″ and a width  1016  of 2.280″. Distances  1010 ,  1012 , and  1018  between mounting holes is 1.750″, 1.457″, and 1.780″, respectively. A bottom mounting plate  878  of apparatus  800 , represented in  FIG. 10B , has a length  1020  of 3.447″ and a width  1022  of 1.280″.  FIG. 11  is further directed to the configuration and layout of apparatus  800 . Apparatus  800  has an overall length  1014  of 3.907″ and height  1026  of 2.5″. Distance  1024  between the edges of potentiometer  880  and servo  802  is 3.008″. Distance  1028  from the edges of top mounting plate  876  and bottom mounting plate  878  is 1.12″. Also, distance  1030  from the top edge of auxiliary shaft  842  to the bottom of servo  802  is 2.235″. 
     It should be noted that all measurements provided herein are provided for the purpose of giving a complete description only. The present invention is not so limited. Other measurements are certainly within the scope of the present invention. It should also be noted that throughout the present description, preference numerals that are the same within multiple figures are intended to designate features that are the same or similar to another. 
       FIG. 12A  illustrates a disassembled apparatus  800  including external potentiometer  880 , top mounting plate  876 , bottom mounting plate  878 , brass bushing  882 , servo pinion gear  884 , large spur gear  886 , washer  888 , hub  890 , hub mounting screws  892 , servo mounting screws  894 , short standoff posts  896 , and standoff mounting screws  898 . Modified servo  802  (with mechanical stops removed and potentiometer wires disconnected (illustrated in  FIGS. 9A-9K ) is not shown.  FIG. 12B  illustrates bolting external potentiometer  880  to bottom mounting plate  878 . Brass bushing  882  is inserted into the hole contained in top mounting plate  876 , making sure that the bushing is flush with the surface of the plate ( FIG. 12C ). Next, with the bushing flange facing upward, the four servo mounting screws  894  are used to mount modified servo  802  to top mounting plate  876  as shown in  FIG. 12D . The bolts should not be over-tightened as they need to be loose to properly mesh the gears later. Further, the standoff posts  896  are mounted using the standoff screws  898  and hand-tightened as illustrated in  FIG. 12E .  FIG. 12F  illustrates mounting bottom plate  878  to top plate  876  by pushing the output shaft of potentiometer  880  through the front plate and using standoff screws  898  to secure both plates to the standoff posts  896 . Hub  890  is mounted to large spur gear  886  using hub mounting screws  892  ( FIG. 12G ). Large spur gear  886  is mounted onto the shaft of potentiometer  880  ( FIG. 12H ). Illustratively in  FIG. 12I , the wires  1210  are connected (soldered) to external potentiometer  880  in the same arrangement they were removed in  FIG. 9F  (i.e. green/white=left, yellow=center, red=right). The servo  802  is pushed up such that the servo gear  850  functionally connects to large spur gear  886 , and screws  894  are tightened ( FIG. 12J ).  FIG. 12K  illustrates apparatus  800  assembled in accordance with  FIGS. 12A-J . It is important to note that apparatus  800  may be used in a variety of different applications. Based on requirements and availability of components, variations may be employed to the configuration of apparatus  800  to achieve enhanced servo performance. 
     Although the present invention has been described with reference to preferred embodiments, workers skilled in the art will recognize that changes may be made in form and detail without departing from the spirit and scope of the invention.