Patent Publication Number: US-2022218430-A1

Title: User Controller With User Presence Detection And Related Systems And Methods

Description:
CROSS-REFERENCE TO RELATED APPLICATION(S) 
     This application claims priority as a continuation application to U.S. patent application Ser. No. 16/896,678, filed Jun. 9, 2020 and entitled “User Controller with User Presence Detection and Related Systems and Methods,” which issued as U.S. Pat. No. 11,284,958 on Mar. 29, 2022, which claims priority as a continuation to U.S. patent application Ser. No. 15/826,166, filed Nov. 29, 2017, and entitled “User Controller with User Presence Detection and Related Systems and Methods,” which issued as U.S. Pat. No. 10,675,110 on Jun. 9, 2020, which claims priority to U.S. Provisional Application 62/427,357, filed Nov. 29, 2016, and entitled “Controller with User Presence Detection and Related Systems and Methods,” all of which are hereby incorporated herein by reference in their entireties. 
    
    
     FIELD OF THE INVENTION 
     The various embodiments herein relate to user presence detection on a multi-degree-of-freedom (DOF) user input device for use in systems such as, for example, robotic medical device systems. 
     BACKGROUND OF THE INVENTION 
     User input devices with many degrees of freedom require the user to support the mass of the input device. 
     One example of such a known input device is depicted in  FIGS. 1-2B .  FIG. 1  depicts the multi-DOF user input device  8  for the left hand of the user. To interface with the device  8 , the user places the left palm on the main body  10  of the user controller  8 , the forefinger on the forefinger interface  12  that is able to move relative to the main body  10  via a rotary link  14 , and the thumb in the thumb groove  16 . The main body  10  of the user interface  8  is connected to a multi-DOF positioning or sensing system through a linkage  18 . In order to supply forces and torques to move the user interface  8  both a thumb restraint  20  and forefinger restraint  22  to constrain the users hand to the device  8 . 
       FIGS. 2A and 2B  depict the ability of the user to further input an open/close motion of the forefinger interface  12 , which is connected to the main body  10  using a link  14  and rotary joint  30 . The minimum displacement  32  (as shown in  FIG. 2A ) and maximum displacement  34  (as shown in  FIG. 2B ) can be measured and used as an additional control signal. The thumb restraint  20  and forefinger restraint  22  supply constraints such that the user maintains control of the main body  10  while moving the grasper throughout its range of motion. Such restraints, while enabling the user to input another control signal, make it difficult for the user to disengage with the device  8  in a controlled manner. 
     Further, in order for the user to exit the device in a controlled fashion, support of the input device must transferred to the input device itself or the signal being output by the device must cease. That is, during use, the input device is supported or maintained in its operable position by the hand of the user, but removal of the user&#39;s hand from the input device without any mechanical force applied by the system itself causes the input device to be pulled downward by gravity, which can result in the robotic device or component operably coupled to the input device to move or be actuated in an undesirable fashion. 
     There is a need in the art for improved methods and devices for detecting the presence of a user at, on, or using a user input device. 
     BRIEF SUMMARY OF THE INVENTION 
     Discussed herein are various user controllers for use with various systems, including robotic surgical systems. 
     In Example 1, a user controller comprises a controller body and a thumb sheath coupled to the controller body. The thumb sheath comprises a first sheath section extending from the controller body, and a second sheath section extending from the first sheath section, wherein the second sheath section is transverse to the first sheath segment. The first sheath section, the second sheath section, and the controller body define a thumb opening and an open side. 
     Example 2 relates to the user controller according to Example 1, wherein the first sheath section, the second sheath section, and the controller body do not form a 360° enclosure around the thumb opening. 
     Example 3 relates to the user controller according to Example 1, further comprising a light sensor disposed within the thumb opening. 
     Example 4 relates to the user controller according to Example 1, further comprising a light emitter disposed on an inner wall of the thumb sheath and a light receiver disposed on the controller body, wherein the light receiver is positioned to receive light transmitted by the light emitter. 
     Example 5 relates to the user controller according to Example 1, further comprising a light emitter disposed on the controller body and a light receiver disposed on an inner wall of the thumb sheath, wherein the light receiver is positioned to receive light transmitted by the light emitter. 
     Example 6 relates to the user controller according to Example 1, further comprising a light emitter and a light receiver, wherein the light emitter and light receiver are disposed on the controller body. 
     Example 7 relates to the user controller according to Example 1, further comprising a capacitive sensor disposed on the controller body within the thumb sheath. 
     Example 8 relates to the user controller according to Example 1, further comprising a mechanical sensor disposed on the controller body within the thumb sheath. 
     Example 9 relates to the user controller according to Example 1, wherein the thumb sheath is adjustable between a retracted position and an extended position. 
     Example 10 relates to the user controller according to Example 1, further comprising a feedback signal component disposed on an outer surface of the thumb sheath, wherein the feedback signal component is visible to a user. 
     Example 11 relates to the user controller according to Example 1, wherein a user&#39;s thumb is removable from the thumb sheath via the thumb opening or the open side. 
     In Example 12, a robotic surgical system comprises a system controller, a robotic surgical device operably coupled to the system controller, and a user controller operably coupled to the system controller. The robotic surgical device comprises a device body, at least one robotic arm operably coupled to the device body, and at least one end effector operably coupled to the robotic arm. The user controller comprises a controller body, and a thumb sheath coupled to the controller body, wherein the thumb sheath and the controller body define a thumb opening and a side opening. 
     Example 13 relates to the robotic surgical system according to Example 12, wherein the thumb sheath comprises a first sheath section extending from the controller body and defining a first wall of the thumb opening, a second sheath section extending from the first sheath second and defining a second wall of the thumb opening, and a third wall of the thumb opening defined by the controller body. 
     Example 14 relates to the robotic surgical system according to Example 13, wherein the side opening is defined between the second wall and the third wall. 
     Example 15 relates to the robotic surgical system according to Example 12, wherein the thumb sheath does not form a 360° enclosure around the thumb opening. 
     Example 16 relates to the robotic surgical system according to Example 12, further comprising a thumb presence sensor disposed within the thumb opening. 
     Example 17 relates to the robotic surgical system according to Example 16, wherein the thumb presence sensor comprises a light sensor, a capacitive sensor, or a mechanical sensor. 
     Example 18 relates to the robotic surgical system according to Example 12, wherein the thumb sheath is adjustable between a retracted position and an extended position. 
     Example 19 relates to the robotic surgical system according to Example 12, further comprising a feedback signal component disposed on an outer surface of the thumb sheath, wherein the feedback signal component is visible to a user. 
     Example 20 relates to the robotic surgical system according to Example 12, wherein a user&#39;s thumb is removable from the thumb sheath via the thumb opening or the side opening. 
     While multiple embodiments are disclosed, still other embodiments of the present invention will become apparent to those skilled in the art from the following detailed description, which shows and describes illustrative embodiments of the invention. As will be realized, the invention is capable of modifications in various obvious aspects, all without departing from the spirit and scope of the present invention. Accordingly, the drawings and detailed description are to be regarded as illustrative in nature and not restrictive. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of a known user input device. 
         FIG. 2A  is a top view of the known user input device of  FIG. 1 . 
         FIG. 2B  is another top view of the known user input device of  FIG. 1 . 
         FIG. 3  is a perspective view of a user input device with a thumb sheath, according to one embodiment. 
         FIG. 4  is a perspective view of a user input device with a thumb sheath and a light-based sensor, according to one embodiment. 
         FIG. 5  is a perspective view of a user input device with a thumb sheath and another light-based sensor, according to a further embodiment. 
         FIG. 6  is a schematic depiction of a known circuit configuration for use with a light-based sensor, according to one embodiment. 
         FIG. 7  is a perspective view of a user input device with a thumb sheath and a capacitive sensor, according to one embodiment. 
         FIG. 8  is a schematic depiction of a known circuit configuration for use with a capacitive sensor, according to one embodiment. 
         FIG. 9  is a schematic depiction of a known circuit configuration for use with a mechanical sensor, according to one embodiment. 
         FIG. 10  is a perspective view of a user input device with a thumb sheath and a sensory signal, according to one embodiment. 
         FIG. 11A  is a perspective view of a user input device with an adjustable thumb sheath in a retracted position, according to a further embodiment. 
         FIG. 11B  is a perspective view of a user input device with an adjustable thumb sheath in an extended position, according to a further embodiment. 
         FIG. 12  is a perspective view of a user input device with a thumb sheath and a mechanical sensor, according to one embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     The various embodiments herein relate to methods and devices for detecting the presence of a user at, on, or using a multi-DOF user input device in which the user grasps the device using a pincer grasp. That is, the various embodiments have a sheath mounted on the input device that is configured to detect the presence of the user&#39;s hand. If the user&#39;s hand (or more specifically the thumb, according to certain embodiments) is detected by the sheath, the device transmits a signal (“the presence signal”) to the system (such as, for example, the system controller component of the system) that the user is in position and control should be enabled. When the hand is removed, the absence of the “presence signal” can be used to cease use of the device output or, if it is haptically enabled, lock the device in place. 
     It is understood that the various user controller embodiments herein can be used with various robotic surgical systems in which the user controller is the user interface and is coupled to the surgical system such that the user controller can be used to control a robotic surgical device positioned into or within a cavity of a patient. That is, the various user controller embodiments and related systems and methods disclosed herein can be incorporated into, used in conjunction with, or used as part of any other known robotic surgical systems, devices, or methods. For example, the various embodiments disclosed herein may be incorporated into or used with any of the medical devices and systems disclosed in U.S. Pat. No. 8,968,332 (issued on Mar. 3, 2015 and entitled “Magnetically Coupleable Robotic Devices and Related Methods”), U.S. Pat. No. 8,834,488 (issued on Sep. 16, 2014 and entitled “Magnetically Coupleable Surgical Robotic Devices and Related Methods”), U.S. patent application Ser. No. 14/617,232 (filed on Feb. 9, 2015 and entitled “Robotic Surgical Devices and Related Methods”), U.S. Pat. No. 9,579,088 (issued on Feb. 28, 2017 and entitled “Methods, Systems, and Devices for Surgical Visualization and Device Manipulation”), U.S. Pat. No. 8,343,171 (issued on Jan. 1, 2013 and entitled “Methods and Systems of Actuation in Robotic Devices”), U.S. Pat. No. 8,828,024 (issued on Sep. 9, 2014 and entitled “Methods and Systems of Actuation in Robotic Devices”), U.S. patent application Ser. No. 14/454,035 (filed Aug. 7, 2014 and entitled “Methods and Systems of Actuation in Robotic Devices”), U.S. patent application Ser. No. 12/192,663 (filed Aug. 15, 2008 and entitled Medical Inflation, Attachment, and Delivery Devices and Related Methods”), U.S. patent application Ser. No. 15/018,530 (filed Feb. 8, 2016 and entitled “Medical Inflation, Attachment, and Delivery Devices and Related Methods”), U.S. Pat. No. 8,974,440 (issued on Mar. 10, 2015 and entitled “Modular and Cooperative Medical Devices and Related Systems and Methods”), U.S. Pat. No. 8,679,096 (issued on Mar. 25, 2014 and entitled “Multifunctional Operational Component for Robotic Devices”), U.S. Pat. No. 9,179,981 (issued on Nov. 10, 2015 and entitled “Multifunctional Operational Component for Robotic Devices”), U.S. patent application Ser. No. 14/936,234 (filed on Nov. 9, 2015 and entitled “Multifunctional Operational Component for Robotic Devices”), U.S. Pat. No. 8,894,633 (issued on Nov. 25, 2014 and entitled “Modular and Cooperative Medical Devices and Related Systems and Methods”), U.S. Pat. No. 8,968,267 (issued on Mar. 3, 2015 and entitled “Methods and Systems for Handling or Delivering Materials for Natural Orifice Surgery”), U.S. Pat. No. 9,060,781 (issued on Jun. 23, 2015 and entitled “Methods, Systems, and Devices Relating to Surgical End Effectors”), U.S. patent application Ser. No. 14/745,487 (filed on Jun. 22, 2015 and entitled “Methods, Systems, and Devices Relating to Surgical End Effectors”), U.S. Pat. No. 9,089,353 (issued on Jul. 28, 2015 and entitled “Robotic Surgical Devices, Systems, and Related Methods”), U.S. patent application Ser. No. 14/800,423 (filed on Jul. 15, 2015 and entitled “Robotic Surgical Devices, Systems, and Related Methods”), U.S. patent application Ser. No. 13/573,849 (filed Oct. 9, 2012 and entitled “Robotic Surgical Devices, Systems, and Related Methods”), U.S. patent application Ser. No. 13/738,706 (filed Jan. 10, 2013 and entitled “Methods, Systems, and Devices for Surgical Access and Insertion”), U.S. patent application Ser. No. 13/833,605 (filed Mar. 15, 2013 and entitled “Robotic Surgical Devices, Systems, and Related Methods”), U.S. patent application Ser. No. 14/661,465 (filed Mar. 18, 2015 and entitled “Methods, Systems, and Devices for Surgical Access and Insertion”), U.S. Pat. No. 9,498,292 (issued on Nov. 22, 2016 and entitled “Single Site Robotic Devices and Related Systems and Methods”), U.S. patent application Ser. No. 15/357,663 (filed Nov. 21, 2016 and entitled “Single Site Robotic Devices and Related Systems and Methods”), U.S. Pat. No. 9,010,214 (issued on Apr. 21, 2015 and entitled “Local Control Robotic Surgical Devices and Related Methods”), U.S. patent application Ser. No. 14/656,109 (filed on Mar. 12, 2015 and entitled “Local Control Robotic Surgical Devices and Related Methods”), U.S. patent application Ser. No. 14/208,515 (filed Mar. 13, 2014 and entitled “Methods, Systems, and Devices Relating to Robotic Surgical Devices, End Effectors, and Controllers”), U.S. patent application Ser. No. 14/210,934 (filed Mar. 14, 2014 and entitled “Methods, Systems, and Devices Relating to Force Control Surgical Systems), U.S. patent application Ser. No. 14/212,686 (filed Mar. 14, 2014 and entitled “Robotic Surgical Devices, Systems, and Related Methods”), U.S. patent application Ser. No. 14/334,383 (filed Jul. 17, 2014 and entitled “Robotic Surgical Devices, Systems, and Related Methods”), U.S. patent application Ser. No. 14/853,477 (filed Sep. 14, 2015 and entitled “Quick-Release End Effectors and Related Systems and Methods”), U.S. patent application Ser. No. 14/938,667 (filed Nov. 11, 2015 and entitled “Robotic Device with Compact Joint Design and Related Systems and Methods”), U.S. patent application Ser. No. 15/227,813 (filed Aug. 3, 2016 and entitled “Robotic Surgical Devices, Systems, and Related Methods”), U.S. patent application Ser. No. 15/599,231 (filed May 18, 2017 and entitled “Robotic Surgical Devices, Systems, and Related Methods”), U.S. patent application Ser. No. 15/691,087 (filed Aug. 30, 2017 and entitled “Robotic Device with Compact Joint Design and an Additional Degree of Freedom and Related Systems and Methods”), U.S. Patent Application 62/425,149 (filed Nov. 22, 2016 and entitled “Improved Gross Positioning Device and Related Systems and Methods”), U.S. Patent Application 62/433,837 (filed Dec. 14, 2016 and entitled “Releasable Attachment Device for Coupling to Medical Devices and Related Systems and Methods”), and U.S. Pat. No. 7,492,116 (filed on Oct. 31, 2007 and entitled “Robot for Surgical Applications”), U.S. Pat. No. 7,772,796 (filed on Apr. 3, 2007 and entitled “Robot for Surgical Applications”), and U.S. Pat. No. 8,179,073 (issued May 15, 2011, and entitled “Robotic Devices with Agent Delivery Components and Related Methods”), all of which are hereby incorporated herein by reference in their entireties. 
     Thus, the various user controller  8  embodiments disclosed or contemplated herein can be used with any robotic surgical system to operate a robotic device or a component thereof, including such a device that is positioned in or through an incision into a target cavity or tissue of a patient. As such, the user utilizes her thumb and forefinger to manipulate the user controller  8 , which thereby actuates the device or components thereof to perform a desired procedure. 
       FIG. 3  depicts a user controller  8  according to one embodiment having a thumb sheath (also referred to as a “enclosure,” “sleeve,” or “shroud”)  40 , instead of a thumb restraint as discussed above in relation to  FIGS. 1-2B . As used herein, “sheath,” “enclosure,” “sleeve,” or “shroud” is intended to mean any structure that encloses the user&#39;s thumb on three sides while defining an opening on the fourth side through which the user can remove her thumb. The thumb sheath  40  surrounds the thumb on two sides, with the main body  10  restraining on a third side, leaving a single side open. More specifically, the sheath  40  has a first section  40 A extending from the body  10  and a second section  40 B extending from the first section  40 A in a direction substantially transverse to the first section  40 A, thereby enclosing two sides around the thumb opening  48  such that the thumb opening  48  is defined by the first section  40 A, the second section  40 B, and the thumb groove  16 . Alternatively, the device  8  need not have a thumb groove—the body  10  can define the third side in such implementations. As a result, the thumb sheath  40  and the thumb groove  16  or body  10  further define an open side  49  as shown. In contrast, the known thumb restraint  20  discussed above operates in conjunction with the thumb groove  16  to entirely surround or enclose the thumb on four sides—the entire 360° around the thumb. 
     In one embodiment, the thumb sheath  40  can sufficiently constrains the user&#39;s thumb when it is positioned within the thumb opening  48  such that the thumb can be used to perform a “pinching motion” in conjunction with the forefinger to cause the forefinger restraint  22  to move away from or closer to the body  10  in the directions represented by arrow  42 . As such, the thumb sheath  40  can operate in a fashion similar to the known thumb restraint  20  discussed above. In contrast to that restraint  20 , however, the sheath  40  also allows two methods of egress for the thumb. That is, the user&#39;s thumb can not only be retracted proximally in the direction represented by arrow  46  in the same fashion as possible with the known thumb restraint  20 , but can also be moved out of the thumb opening  48  in the direction represented by arrow  44  through the open side  49 . As can be seen in  FIG. 3 , the two directions of potential egress are normal to the direction of pinching (represented by arrow  42 ) and each other. As such, this configuration of the sheath  40  allows for both fine control of pinching motion while enabling the user to disengage from the device  8  by removing her thumb in a controlled and simple manner. 
     To clarify, the term “user controller” as used herein will refer to the various embodiments of a user input device to be manipulated by a user to provide input to and thereby operate some portion of a robotic system. In contrast, the term “system controller” will refer to any processor, computer or other system controller component (such as a microprocessor or the like) that can be used to operate a system. 
       FIG. 4  depicts a further implementation of a user controller  8  having a sensor  51  configured to detect the presence of the user&#39;s thumb. It is understood that this embodiment of the controller  8  has a thumb sheath  40  substantially similar to the sheath  40  described above, including the features and benefits as described. Further, in this exemplary implementation, a user presence sensor  51  is incorporated into the sheath  40 . The device  8  has a matched light emitter  50  disposed on the sheath  40  and a receiver  52  disposed on the body  10 . Alternatively, the emitter can be on the body  10  and the receiver can be on the sheath  40 . In a further alternative, two or more such sensors can be incorporated into the device  8 . The emitter  50  and receiver  52  are positioned in a manner which generally aligns the path of light  54  transmitted by the emitter  50  with the direction of motion of the pinching motion as represented by arrow  42 . In use, the emitter  50  and receiver  52  are placed such that when the user&#39;s thumb is not present, light (visible or otherwise) from the emitter  50  reaches the receiver  52 . In contrast, when the user&#39;s thumb is present within the thumb opening  48 , the path of the light  54  is blocked. The absence of this signal can then be used as an indicator of user presence (that is, the presence of the user&#39;s thumb within the thumb opening  48 ), thereby indicating that the user is grasping the user controller  8 . Once the light path is blocked by the user&#39;s thumb, restoration of this signal, an indicator of user absence, is achieved by retracting the thumb in either of two directions as represented by arrows  44  and  46 , which are normal to the direction of pinching represented by arrow  42  and the path of light  54  (as discussed above). This configuration of sheath  40  and sensor  51  allows for motion of the thumb in the direction of pinching (as represented by arrow  42 ) without allowing light to pass. This allows for the sheath  40  to be sufficiently loose such that egress is easily achieved. That is, the size of the thumb opening  48  in relation to the user&#39;s thumb does not impact the ability of the sensor  51  to detect the presence therein or the ability of the user to utilize the sheath  40  to allow the user to utilize the pinching motion to move the forefinger restraint as discussed above. 
     Alternatively, any known sensor or sensor technology can be used with the user controller  8  to detect the presence (and absence) of the user&#39;s thumb within the sheath  40 . 
     The sensor  51  allows for the user controller  8  (and the system to which the controller  8  is coupled) to utilize the information about the presence or absence of the user&#39;s thumb to activate or deactivate mechanical support of the user controller  8 . That is, the sensor  51  can be configured to transmit a “presence” signal to the system controller (not shown) of the system (not shown) when the thumb is inserted into the sheath  40  such that the system controller deactivates any mechanical support of the user controller  8 . Similarly, the sensor  51  can also be configured to transmit an “absence” signal to the system controller (not shown) when the thumb is retracted from the sheath  40  such that the system controller activates mechanical support of the user controller  8 , thereby preventing gravity from causing the user controller  8  from moving in an undesirable fashion that causes the controlled robotic device to also move in an undesirable fashion. 
       FIG. 5  depicts an alternative embodiment of a user controller  8  having a reflected light sensor  61 . That is, the user controller  8  has an emitter  60  and a receiver  62  that are both embedded in the main body  10  as shown such that the emitted light  64  from the emitter  60  returns to the receiver  62  as reflected light  66  by the nearest occlusion. In this configuration, the presence of the user&#39;s thumb within the sheath  40  provides a much shorter path than the sheath  40  and thus a corresponding stronger return signal than would be detected in the absence of the thumb. This signal can then be thresholded to determine the binary presence/absence of the user&#39;s thumb. That is, a predetermined threshold can be established above which it is understood that a user&#39;s thumb is present in the sheath  40  such that a presence signal is transmitted to the system controller (not shown). In one implementation, it is understood that this embodiment has substantially the same features, modes of egress, and advantages, including insensitivity to motion in the direction of pinching motion, as the previously described embodiments. 
       FIG. 6  depicts an exemplary known circuit for use in conjunction with a sensor such as either of the sensors  51 ,  61  discussed above with respect to  FIGS. 4 and 5  for detecting the presence of a user&#39;s thumb within the sheath  40 . In this embodiment, one or more pairs of infrared (IR) emitters and detectors are provided that are similar to those described in  FIG. 4  or  FIG. 5 . The presence of the user&#39;s thumb blocks the IR light from the emitter from reaching the detector, changing the output state of the circuit. Each emitter/detector pair described uses the circuit in  FIG. 6  to detect presence. When the user&#39;s thumb is absent from the device, phototransistor Q 1  receives IR light from LED 1 . This turns the transistor on, causing a current to flow through resistor R 1 , and a non-zero voltage to appear on the non-inverting input (pin  5 ) of the comparator U 1 . If this voltage is higher than the inverting input of U 1 , set by the voltage divider of R 2  and R 3 , the output of the comparator is switched on, lowering the output voltage to 0. When the detector Q 1  is blocked, the transistor is off, and the output of the circuit is 5 volts. Alternatively, any known circuit or circuit configuration can be used for this purpose. 
       FIG. 7  depicts a further embodiment of a sensor  70  for use in a user controller  8 . In this specific implementation, instead of a light-based technology, the sensor  70  is a known capacitive sensor  70  positioned in the main body  10  as shown. The capacitive sensor  70  functions as a known capacitive sensor  70  operates to detect the presence of the user&#39;s thumb within the sheath  40 . According to one embodiment, it is understood that this embodiment has substantially the same features, modes of egress, and advantages, including insensitivity to motion in the direction of pinching motion, as the previously described embodiments. 
       FIG. 8  depicts an exemplary known circuit for use in conjunction with a capacitive sensor such as the sensor  70  discussed above with respect to  FIG. 7  for detecting the presence of a user&#39;s thumb within the sheath  40 , according to another implementation. One or more capacitive sensors are placed on the inner surface of the thumb sheath, such as the sensor  70  in  FIG. 7 . In use, when the user&#39;s thumb is placed in the sheath  40 , the change in capacitance changes the output state of the circuit. Alternatively, any known circuit or circuit configuration that operates in conjunction with a capacitive sensor can be used for this purpose. 
       FIG. 12  depicts a further embodiment of a sensor  120  for use in a user controller  8 . In this specific implementation, instead of a light- or capacitive-based technology, the sensor  120  is a known mechanical sensor  120  positioned in the main body  10  as shown. The mechanical sensor  120  functions as a known mechanical sensor  120  operates to detect the presence of the user&#39;s thumb within the sheath  40 . For example, the mechanical sensor  120  can be actuated by the user&#39;s thumb depressing the sensor  120 , thereby indicating that the thumb is present within the sheath  40 . According to one embodiment, it is understood that this embodiment has substantially the same features, modes of egress, and advantages, including insensitivity to motion in the direction of pinching motion, as the previously described embodiments. 
       FIG. 9  depicts an exemplary known circuit for use in conjunction with a mechanical sensor such as sensor  120  discussed above with respect to  FIG. 12  for detecting the presence of a user&#39;s thumb within the sheath  40 , according to a further embodiment. In this embodiment, a mechanical switch (such as switch  120 ) is placed inside of the thumb sheath  40 . In use, when the user&#39;s thumb is in place, the switch is actuated and the output state of the circuit changes. When the user&#39;s thumb is not in the sheath, the switch is open, and the output of the switch is pulled up to 5 volts. V 1  inverts this signal to a 0 volt output. When the thumb is placed in the sheath, the switch is depressed, which changes the output of the circuit to 5 V. The switch debouncing circuitry is a circuit which filters out short duration transitions of the output when the mechanical switch is engaged and disengaged. Alternatively, any known circuit or circuit configuration that operates in conjunction with a mechanical sensor can be used for this purpose. 
       FIG. 10  depicts a user controller  8  having a user sensory feedback signal component  100 , according to one embodiment. That is, this specific implementation has a signal component  100  that provides some type of sensory feedback to the user about whether the user&#39;s thumb is positioned within the sheath  40 . In the specific embodiment depicted in  FIG. 10 , the feedback signal component  100  is a visual feedback component  100  in the form of an LED  100  that is disposed on the thumb sheath  40 . Alternatively, any form of sensory feedback signal can be used. This feedback component  100  provides feedback to the user regarding whether the system (not shown) detects the presence of the user&#39;s thumb within the sheath  40 . Feedback may be provided by multiple LEDs, auditory, or other visual signals. In use, according to this embodiment, the LED  100  would illuminate if the user&#39;s thumb is detected, thereby indicating that the thumb is positioned within the sheath  40 . It is understood that the user controller  8  with the user feedback signal component  100  can have any of the various sensor components disclosed or contemplated herein. In addition, it is understood that the user feedback signal component  100  can be incorporated into any other embodiment disclosed or contemplated herein. 
       FIGS. 11A and 11B  depict an adjustable sheath  40 , according to one embodiment. More specifically, the sheath  40  in this specific implementation can move between a retracted position as shown in  FIG. 11A  and an extended position as shown in  FIG. 11B . As such, the sheath  40  can be adjusted to be positioned with respect to the main body  10  in the retracted positioned in which the thumb opening  48  has a minimum width represented by arrow  110  (as shown in  FIG. 11A ) or can be extended out away from the body  10  up to the extended position in which the thumb opening  48  has a maximum width represented by arrow  112  (as shown in  FIG. 11B ). This adjustability enables the sheath  40  to conform to a wide array of user thumb sizes while supplying sufficient control authority to the user while still enabling the user to disengage in a controlled manner. It is further understood that the user controller  8  with the adjustable sheath  40  can have any of the various sensor or sensory feedback components disclosed or contemplated herein. In addition, it is understood that the adjustable sheath  40  can be incorporated into any other embodiment disclosed or contemplated herein. 
     Although the present invention has been described with reference to preferred embodiments, persons 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.