Patent Publication Number: US-11040458-B2

Title: Hair cutting device for automated hair cutting system

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     This application claims the benefit of U.S. Provisional Application Ser. No. 61/747,775, filed by Matthew W. Krenik on Dec. 31, 2012, entitled “Hair Cutting Device for Automated Hair Cutting System”; and U.S. Provisional Application Ser. No. 61/780,086, filed by Matthew W. Krenik on Mar. 13, 2013, entitled “Techniques for Automated Hair-Cutting System,” the entire contents of both are incorporated herein by reference. 
    
    
     FIELD OF THE DISCLOSURE 
     Embodiments of this disclosure relate to improved designs for hair cutting devices for automated hair cutting systems. These improved designs may provide more options for how a hair cutting device is held in a human hand and maneuvered, improved location of position sensors and cameras, improved balance, improved cutter head actuation, attachment of electrically powered accessories, and additional benefits. 
     BACKGROUND 
     International application number PCT/US12/70856, filed by Matthew W. Krenik on Dec. 20, 2012, entitled “Automated Hair Cutting System and Method of Operation Thereof,” (hereinafter “Krenik &#39;856”) provides a description of automated hair cutting systems. These systems operate by determining the position and/or orientation of a hair cutting device relative to a user receiving a haircut. Hair may be collected in a cutter head and extended for cutting to a beneficial length. Through electronic measurements and computational analysis, the location of where hair on the scalp of a user is collected into a cutter head may be determined and as hair is extended and slides through a cutter head, its length may be substantially determined so that a cutter head may be actuated at a beneficial time to cut hair to a beneficial length. 
     Krenik &#39;856 relates to multiple hair cutting devices that include sensors suitable for determining the position and/or orientation of a hair cutting device relative to the head of a user receiving a haircut. Since the use of an automated hair cutting system involves manipulation of a hair cutting device around the head of a user, hair cutting devices that may be grasped in multiple ways, that have sensors positioned so that they may extend around a hand or between the fingers of a hand grasping a hair cutting device so that they are less likely to be blocked by such a hand, are balanced to improve ease of manipulation, are designed to interoperate with positioning devices so that interference between a hair cutting device and a positioning device is minimized, incorporate structures to support sensors that may be folded or adjusted, and may be interfaced with electrically powered accessories are highly desirable. 
     U.S. patent application Ser. No. 14/051,201 filed by Matthew W. Krenik on Oct. 10, 2013, entitled “Cutter Head for Automated Hair Cutting System,” (hereinafter “Krenik &#39;201”) provides embodiments of cutter heads suitable for use with automated hair cutting systems. The embodiments of hair cutting devices shown in this patent application may utilize the cutter heads shown in Krenik &#39;201, the cutter heads described in this patent application, or other suitable cutter heads. U.S. patent application Ser. No. 14/086,497 filed by Matthew W. Krenik on Nov. 21, 2013, entitled “Sensing and Control Techniques for Automated Hair Cutting System,” (hereinafter “Krenik &#39;497”) provides embodiments of sensing, actuation, and control systems for cutter heads for automated hair cutting systems. The embodiments of hair cutting devices shown in this patent application may utilize the sensing, actuation, and control systems shown in Krenik &#39;497, those described in this patent application, or other suitable sensing, actuation, and control systems. 
     SUMMARY 
     In one embodiment, a cutting device for use with an automated hair cutting system is disclosed. The cutting device comprises a body having a proximal end and a distal end. A cutter head is attached to the distal end of the body, the cutter head is configured for manipulating and cutting hair. The cutting device further comprises a plurality of sensors coupled to the body for sensing a position of the cutter head relative to a user&#39;s head. 
     In one embodiment, there is disclosed an automated hair cutting system. The system comprises a positioning apparatus including a support apparatus for supporting the positioning apparatus about a user&#39;s head and the positioning apparatus having positioning interfaces positioned about the support apparatus; a computing device including a user interface; and a cutting device. The cutting device comprises a body having a proximal end and a distal end; a cutter head attached to the distal end of the body, the cutter head configured for manipulating and cutting hair; and a plurality of sensors coupled to the body for sensing a position of the cutter head relative to the user&#39;s head. The cutting device may be configured to communicate with the computing device, and in some embodiments, the plurality of sensors are positioned such that the cutting device and positioning apparatus may be used in conjunction with each other. 
     In yet another embodiment, a method of manufacturing a cutting device for use with an automated hair cutting system for cutting hair on a user&#39;s head is disclosed. The method comprises forming a body having a proximal end and a distal end and coupling a cutter head to the distal end of the body, the cutter head configured for manipulating and cutting hair. The method further comprises coupling a plurality of sensors to the body and configuring the plurality of sensors for sensing a position of the cutter head relative to the user&#39;s head. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is an environmental view of an automated hair cutting system having a cutting device according to the present disclosure; 
         FIG. 2  shows a perspective view of an embodiment of a cutter head which may be used with the automated hair cutting system shown in  FIG. 1 ; 
         FIG. 3A  shows a perspective view of an embodiment of a hair cutting device according to the present disclosure which may be used in the system shown in  FIG. 1 ; 
         FIG. 3B  shows one embodiment of manipulating the hair cutting device shown in  FIG. 3A ; 
         FIG. 3C  shows another embodiment of manipulating the hair cutting device shown in  FIG. 3A ; 
         FIG. 4  shows a top view of an embodiment of a positioning device mounted on a human head; 
         FIG. 5  shows a perspective view of another embodiment of a hair cutting device according to the present disclosure; 
         FIG. 6  shows a perspective internal view of a portion of a hair cutting device similar to the embodiment of  FIG. 5 ; 
         FIG. 7  shows an exploded view of one embodiment of a cutter head according to the present disclosure; 
         FIG. 8  shows a perspective view of another embodiment of a hair cutting device according to the present disclosure; 
         FIG. 9  shows a perspective view of yet another embodiment of a hair cutting device according to the present disclosure; 
         FIG. 10  shows a detailed perspective view of one aspect of a hair cutting device according to the present disclosure; 
         FIG. 11  shows a perspective view of yet another embodiment of a hair cutting device according to the present disclosure; and 
         FIG. 12  shows an exploded view of another aspect of a hair cutting device according to the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     Embodiments of this disclosure include techniques for how position sensors or cameras on a hair cutting device for use in an automated hair cutting system are located and mounted and how hair cutting devices may be constructed for beneficial use. Such improved locations and mounts may allow persons using an automated hair cutting system more options for how to hold and maneuver a hair cutting device so that they may more comfortably and effectively achieve desirable results. Such improved locations and mounts may also allow position sensors or cameras to be substantially less likely to be blocked so that they are more effective in providing signals that may be used to determine the position and/or orientation of a hair cutting device. Such improved locations and mounts may also be implemented so they are substantially less likely to snag hair that may be in close proximity to them in the course of providing a haircut. Improved construction of hair cutting devices may allow them to be grasped in multiple ways and to be manipulated more easily than may otherwise be possible. Hair cutting devices may include a main body from which a handle extends. A main body may house electronics, actuators, and other system elements and may also attach or adjoin an additional body or bodies that may also house system elements. Embodiments of this disclosure may also include improved balance of hair cutting devices. Improved balance may improve user comfort and may also allow a hair cutting device to be more easily maneuvered for beneficial results. Improved balance may be achieved by preferred location of batteries, electronics, and other internal elements of a hair cutting device, and may also include use of ballast weights. 
     Hair cutting devices may also be designed to interoperate with specific positioning devices and may have physical dimensions and placement of sensors and supporting structures that are configured to minimize undesired interference between a hair cutting device and a positioning device. In some possible embodiments, a hair cutting device may have sensor supporting structures that are larger, so that sensors may be more broadly spaced, on a side of a hair cutting device from which cutter head teeth substantially emanate and point away from and sensor supporting structures that are smaller, so that they interfere less with a positioning device, on the side of the hair cutting device opposite the direction that cutter head teeth substantially point. Hair cutting devices may include relief areas between a cutter head supporting structure and a main body so that a cutter head may be more easily manipulated around ears and other features of a user&#39;s head. Actuators and cutter head drive mechanisms may be designed to allow such relief areas and may provide variable forces on cutter heads to reduce friction and power levels used during some phases of cutter head operation and provide reliable cutting action in other phases of cutter head operation. Structures or posts supporting sensors on hair cutting devices may be folded for compact storage or may be adjusted in the course of operation. Structures supporting sensors may provide passive channels or guides so that positioning signals may propagate around or inside a supporting structure to sensing electronics located some distance from the point where a positioning signal is actually sensed. Accessories, such as an electrically powered shaving accessory, trimmer, hair thinning cutter, or other useful accessory, may be mounted to and be powered and/or controlled by a hair cutting device. And unpowered accessories may also be mounted to and possibly controlled by a hair cutting device. 
     Referring now to the drawings and more specifically to  FIG. 1 , there is shown an automated hair cutting system  100  cutting a region of hair  110  on a user  102 . An electronic computing device  108  may communicate and interact with a positioning device  104  having a plurality of positioning interfaces  106  and with a hair cutting device  300 . Embodiments of automated hair cutting systems such as automated hair cutting system  100  are described in more detail in Krenik &#39;856. Hair cutting system  100  is shown in  FIG. 1  utilizing hair cutting device  300  according to one embodiment of the present disclosure. The hair cutting device  300  includes cutter head  302 . Hair cutting system  100  may operate through observation of and/or interaction with user  102  and/or positioning device  104  by hair cutting device  300 , or other system elements which enable determining the position and/or orientation of hair cutting device  300  relative to the head of user  102  such that selected regions of hair  110  may be collected, extended to a length, and cut by cutter head  302  of hair cutting device  300 . Additional embodiments, modes of operation and additional description of automated hair cutting system  100  may be found in Krenik &#39;856. 
     Alternate embodiments of an automated hair cutting system are possible which do not utilize a positioning device, but rather use some combination of cameras, motion sensors, accelerometers, gyroscopes, and/or other sensors to determine the position and/or orientation of hair cutting device  300  relative to the head of a user. Other embodiments of automated hair cutting system  100  which use a positioning device may be combined with the use of some combination of cameras, motion sensors, accelerometers, gyroscopes, and/or other sensors to facilitate determining the position and/or orientation of a hair cutting device  300  relative to the head of a user. 
     In  FIG. 1 , hair cutting device  300  is shown supported by human hand  370 . Hair cutting device  300  provides a novel arrangement of sensors and construction for use with an automated hair cutting system such as automated hair cutting system  100 . Positioning device  104  may be supported on the head of user  102  with a support apparatus, which may comprise ear supports  107  and head band  105 . Housing  118  may contain batteries, electronics, or other elements. The support apparatus and other features of positioning device  104  utilize a tubular construction, but those skilled in the art will recognize that alternative structures and constructions for positioning devices may also be used. 
     Embodiments of automated hair cutting systems may include positioning signals between the positioning interfaces  106  on positioning device  104  and sensors on hair cutting device  300  as will be shown and discussed in more detail with regard to  FIGS. 3A-3C . The positioning signals may be electromagnetic signals, sound signals, light signals, magnetic signals, acoustic signals, ultrasonic signals, or other types of signals and may propagate from any of the positioning interfaces  106  to any of the sensors on hair cutting device  300 . Analysis of these positioning signals may be used in computation of the position and/or orientation of hair cutting device  300  relative to user  102 , and may include measurement of signal propagation times and distances from positioning interfaces to sensors, or other aspects of positioning signals that may be beneficial for some embodiments. Computation of the position and/or orientation of hair cutting device  300  relative to user  102  may be undertaken in electronic computing device  108 , hair cutting device  300 , positioning device  104 , or other possible system elements that may be present in some embodiments of automated hair cutting systems  100 . Some embodiments of automated hair cutting system  100  may also comprise a camera or cameras on hair cutting device  300 , positioning device  104 , electronic computing device  108 , or other system elements that may collect images or video of positioning device  104 , user  102 , or hair cutting device  300 , so that analysis of those images or video may be used in computation of the position and/or orientation of hair cutting device  300  relative to user  102 . In Krenik &#39;856, more explanation is provided for a wide range of signal types, signal coding, signal modulation, and types of sensors or transducers that may be used to generate and/or sense these positioning signals, and many other aspects for various embodiments of signals, interfaces, cameras, sensors, and other elements or signals for automated hair cutting systems  100 . Embodiments of hair cutting devices, such as cutting device  300 , will be explained in the present disclosure which may improve the ability to accurately and reliably generate and/or sense signals, images, video, or other useful information for use in determining position and/or orientation of a hair cutting device relative to the head of a user  102 . 
       FIG. 2  shows an embodiment of a cutter head  200  for use in hair cutting devices such as hair cutting device  300  that allows hair to be collected, allows actuation of the cutter knives  204  in a first direction to apply pressure and friction to hair so that it may be manipulated and extended, and provides cutting action when the cutter knives  204  are actuated in a second direction. Cutter head  200  of  FIG. 2  comprises cutter knives  204 , comb teeth  202 , and body  220 . Cutter head  200  may be actuated so that cutter knives  204  are substantially above comb teeth  202  so that hair may be collected in cutter head  200  (the view of  FIG. 2  shows cutter knives  204  in such a position). Cutter head  200  may be actuated so that cutter knives  204  move to the left (toward the lower left corner of  FIG. 2 ) so that rounded edges  208  of cutter knives  204  and comb teeth  202  apply pressure to hair collected in cutter head  200 . Application of pressure to hair collected into cutter head  200  may improve the ability to manipulate hair collected in cutter head  200  as the resulting friction may help to keep hair in cutter head  200  so that it is less likely to fall out. And cutter head  200  may be actuated so that cutter knives  204  move to the right (toward the upper right corner of  FIG. 2 ) so that sharp edges  206  of cutter knives  204  and comb teeth  202  meet and pass over each other to provide a cutting action (much as the blades of a common pair of scissors pass over each other to provide cutting action). Left most comb tooth  203  and right most cutter knife  205  have only rounded edges  208  and have no sharp edges  206  as left most comb tooth  203  and right most cutter knife  205  are not utilized for cutting hair during a cutting stroke of cutter head  200 . Gap  242  and gap  244  provide spacing between cutter knives  204  (including right most cutter knife  205 ) and body  220  so that they may move to the right and left. Cutter head  200  may be fabricated from metals, ceramics, glass, sapphire, and other suitable materials. Cutter head  200  or other possible cutter head embodiments may be utilized for cutter head  302  as shown on hair cutting device  300  and on other hair cutting devices shown in this patent application. Krenik &#39;201 provides additional description of cutter heads similar to cutter head  200  and also describes additional embodiments of cutter heads suitable for some embodiments of hair cutting devices. 
     The teeth of a cutter head may be pointed in different directions. In  FIG. 2 , the teeth of cutter head  200  that emanate from the side of body  220  visible in  FIG. 2  are pointed away from body  220 , and are pointed substantially toward the lower right side of  FIG. 2  in the view shown. This convention, that cutter head teeth point in the direction from which hair may enter a cutter head, is used consistently throughout this patent application. 
     Cutter heads, such as cutter head  200  as shown in  FIG. 2 , cutter heads shown in Krenik &#39;201, and other possible cutter head embodiments, utilized in automated hair cutting system  100  may be used in multiple ways in the course of delivering a haircut to a user  102 . For example, cutter head  200  may include sensors and actuators that allow the position of cutter knives  204  relative to comb teeth  202  to be sensed and controlled by electronic circuitry controlling cutter knives  204  (see Krenik &#39;201 and Krenik &#39;497 for more information on sensing and controlling cutter heads). Control and sensing of cutter knives  204  may allow some embodiments of automated hair cutting system  100  to estimate the amount of hair collected in a cutter head  200 . With such an estimate, a cutter head  200  may be controlled such that sufficient force is provided to cut hair without providing so much force as to create unnecessary levels of vibration or jarring of a hair cutting device. For some hair styling techniques, it may be desirable to not fully cut the hair in a cutter head  200  and to only cut some of the hair that has been collected. For example, some hair cutting techniques involve thinning or layering of hair on some regions of a user&#39;s  102  head. For such a technique, cutter knives  204  may be actuated to cut some, but not all, of the hair collected in a cutter head  200  and this may be achieved by partially actuating cutter knives  204  through a cutting stroke, and then returning cutter knives  204  to a position suitable for extension and possibly the application of friction to hair, so that only a portion of hair collected in cutter head  200  is cut. Multiple cycles of actuation of cutter head  200  to partially cut hair while it is extended may allow the thickness or weight of hair on the head of a user  102  to be tapered along the length of the hair and such multiple cycles of actuation for partial cutting may be sequenced automatically based on the position of a hair cutting device  300  relative to the head of a user  102 . 
     Another common hair cutting technique is to cut hair at various angles with a scissors to create a randomized or feathered texture to hair and to avoid abrupt straight cuts to hair that may be visible and possibly unsightly. A similar technique may be achieved with a cutter head  200  under automatic sensing and control by vibrating cutter knives  204  back and forth within a limited range of motion while hair is extended through an interval including a length at which multiple partial cutting strokes of cutter knives  204  are used to achieve a certain desired hair length. A single abrupt cutting stroke of cutter head  204  is avoided and replaced by multiple partial cutting strokes, possibly culminating in a complete cutting stroke, so that hair is somewhat randomly cut to slightly variable lengths within a controlled range so that a more natural or feathered result is achieved in a user&#39;s  102  cut hair. Those skilled in the art will recognize that a cutter head, such as cutter head  200  shown in  FIG. 2 , may be controlled so that hair may be collected, extended, maneuvered, partially cut, fully cut, randomly cut within pre-determined bounds to the desired length for a given region of collected hair, thinned, or otherwise cut to generate desirable textures, patterns, features, or other possible desirable effects in hair. 
     Referring now to  FIGS. 3A-3C , there is shown one embodiment of a hair cutting device according to the present disclosure and various configurations for manipulating and supporting hair cutting device  300 . In  FIG. 3A , there is shown hair cutting device  300  comprising cutter head  302 , actuator body  304 , main body  306 , and handle  308 . Handle  308  comprises handle end  310 , which may be formed having chamfered corners, although other embodiments may comprise rounded, square or otherwise finished corners. Handle  308  may include grips, which may include rubber grips, plastic grips, grips made of other materials, texturing, smooth or roughened finishes, or other suitable finishes. Although handle  308  is shown having a square cross-section, other embodiments may use round, octagonal, hexagonal, oval, elliptical, triangular, or other possible cross-sections. Handle  308  may also include contours, reliefs, or other shapes to augment comfort, augment the ability of a person to securely grasp handle  308 , or provide other or additional benefits. 
     Handle  308  is shown in  FIG. 3A  as a hollow handle with battery  350  positioned inside. While only one battery  350  is shown in  FIG. 3A , some embodiments may use multiple batteries, longer batteries, batteries that are flat, square, or other shapes as opposed to the cylindrical battery shown in  FIG. 3A . Battery  350  may be a one-time-charged replaceable battery or may be rechargeable. In some embodiments, handle  308  may be removable, have a removable cap on handle end  310 , or other configurations which enable access and/or replacement of battery  350 . In some embodiments hair cutting device  300  may be powered from a power cord or other wired cord capable of delivering power to operate hair cutting device  300 , charge batteries in hair cutting device  300 , or both. Wireless powering or charging of hair cutting device  300  may also be possible for some embodiments. 
     Cutter head  302  may be configured similarly to cutter head  200 , or may be similar to other cutters heads such as those shown and described in Krenik &#39;856, Krenik &#39;201, or other possible cutter heads. Cutter head  302  may comprise reciprocating cutters, cutter teeth, rotary cutters, laser cutters or any other type of suitable cutter design. Actuator body  304  may contain a motor, solenoid, voice coil motor, gears, levers, mechanical features, magnetic elements, electronics, motor drivers, or other electrical and/or mechanical elements that may be configured to provide motion to drive cutter head  302 . Cutter head  302  may comprise sensing and controlling cutter knives or other cutter head  302  elements to allow various manipulations of hair, including, but not limited to collection, extension, partial cutting, or fully cutting of hair. Cutter head  302  is shown having teeth extending in front of the face of actuator body  304  at a substantially right angle to the face of actuator body  304 . Those skilled in the art will recognize that additional embodiments in which the teeth of cutter head  302  extend in front of actuator body  304  at smaller or larger angles than a right angle are possible and may offer benefits in how hair cutting device  300  may be manipulated for some possible embodiments. Embodiments in which the teeth of cutter head  302  extend substantially in parallel away from actuator body  304  (that is, extend outward from actuator body  304  substantially opposite in direction from the direction of main body  306  and substantially parallel to handle  308 ) or extend in other directions are also possible. 
     As cutter head  302  and actuator body  304  may be constructed from or contain metals, cutting elements, actuators, and other elements, the distal end of hair cutting device  300  near cutter head  302  may be somewhat heavier than the proximal end of hair cutting device  300  near handle end  310 . For some embodiments, the weight may make gripping and maneuvering hair cutting device  300  somewhat cumbersome and inconvenient. Some embodiments may benefit from battery  350  placed inside handle  308  at a location such that the weight of battery  350  counters the weight of cutter head  302  and actuator body  304 , thereby facilitating a more balanced hair cutting device which is easier and more convenient to maneuver. In addition to battery  350 , other elements of hair cutting device  300  may be distributed inside handle  308 , main body  306 , and actuator body  304  to benefit balance. Additionally, ballast, other weights, or alternations in the materials, construction, and other elements of hair cutting device  300  may be arranged which facilitate a balanced weight distribution of hair cutting device  300 . 
     Main body  306  may contain electronics, signal processing functions, batteries, power electronics, control electronics, accelerometers, gyroscopes, orientation sensors, motion sensors, analog electronics, digital electronics, communications electronics, interfaces, motors, actuators, buttons, cameras, illumination sources, and other elements beneficial for a hair cutting device  300 . Main body  306  may be configured in various ways and shapes which facilitate manipulation and support of cutting device  300 . Main body  306 , actuator body  304 , and handle  308  together form a central structure of hair cutting device  300 . Many alternative options and configurations of a central structure are possible and may include multiple bodies, housings, handles, grips, knobs, and other alternative structures. Accordingly, one benefit of some embodiments of hair cutting device  300  is incorporation of a central structure with one or more positioning sensors, one or more cameras, and/or other sensors mounted away from the central structure so that a person&#39;s hand may extend substantially between the central structure and one or more of the positioning sensors, cameras, and/or other sensors. 
     While not shown in  FIG. 3A , hair cutting device  300  may include indicator lights, switches, buttons, safety buttons, electronic displays, touch screen displays, bells, chimes, speakers, microphones, a camera or cameras, video cameras, an illumination source, an illumination source suitable for producing structured light, gyroscopes, compasses, accelerometers, electrical communication interfaces, electrical charging interfaces, electrical power interfaces, wired interfaces, wireless interfaces, and other elements. Those skilled in the art will recognize that hair cutting device  300  of  FIG. 3A  may also include other or additional features including adjustable or removable combs, adjustable or removable spacers, accommodations for connection of a vacuum cleaner, accessories, and other elements commonly found on hair clippers, hair trimmers, or other consumer appliances. 
     Certain embodiments of hair cutting device  300  may contain a touch sensor on the base of cutter head  302  that allows hair cutting device  300  to monitor when it touches the scalp of a user  102  and may offer additional capability to measure distance from the scalp of user  102  to hair cutting device  300  (see Krenik &#39;856 for additional information on touch sensors). Use of a touch sensor to signal that cutter head  302  is against the scalp of a user  102  may provide an indication that cutter head  302  has collected hair and extension of hair for cutting may begin. Some embodiments of touch sensors may allow the spongy, elastic, or compliant nature of a human scalp to be sensed and some embodiments of automated hair cutting devices  100  may keep estimates of how spongy, elastic, or compliant a human scalp is relative to position on the human scalp so that differences in how the scalp springs up after being pressed against by cutter head  302  may be accounted for in hair length measurements. Those skilled in the art will recognize that areas of a human scalp composed primary of skin over bone tend to be harder and less compliant while areas such as the back of a human neck where skin is substantially over muscle and other body tissue tend to be more compliant. As hair cutting device  300  is lifted away from a human scalp to extend and cut hair, the level to which the scalp is compliant and springs up, and also may be pulled upward by the action of extending hair, may impact measurements of how long hair has been extended and compensation of these effects may lead to improved results. Embodiments of touch sensors that may provide variable or light pressure in monitoring contact with a scalp and embodiments making use of multiple touch sensors on the base of a cutter head  302  are also possible. 
     Some embodiments of automated hair cutting system  100  may not utilize touch sensors on hair cutting devices  300 , and may instead utilize knowledge of the position and/or orientation of hair cutting device  300  to determine that hair cutting device  300  is resting in a substantially stationary position on user&#39;s  102  scalp, as a signal that hair has been collected in cutter head  302 . Still other embodiments of hair cutting devices may include a button, switch, voice response control, or other technique for a user  102  to signal that hair has been collected in cutter head  302 . And it is also possible in some embodiments to use different methods to signal that hair has been collected in cutter head  302  and that extension of hair for cutting may begin. For example, some embodiments of automated hair cutting system  100  may utilize a touch sensor on the base of cutter head  302  to signal that hair is collected in cutter head  302  on regions of a user&#39;s  102  scalp where the scalp is harder and less compliant, but require a user  102  to press a button to signal that hair has been collected in cutter head  302  in regions of user&#39;s  102  scalp where the scalp is more spongy, elastic, and complaint (such as on the back of user&#39;s  102  neck). 
     Hair cutting device  300  comprises a plurality of sensors  312  mounted on a plurality of sensor posts  322 . While only five sensors are shown and described in the embodiment shown in  FIG. 3A , other embodiments may contain more sensors or less sensors, according to various desired users and configuration requirements. Sensors  312  are shown as spherical elements. Sensors on a hair cutting device such as hair cutting device  300  shown in  FIG. 3A , or other possible embodiments of hair cutting devices may sense electrical, magnetic, electromagnetic, sound, acoustic, ultrasonic, optical, light, infrared light, ultraviolet light, visible light, radar, sonar, lidar, or many other types of signals generated at positioning interfaces  106  on a positioning device  104 . In some embodiments, transmitters may be used in place of the sensors of the hair cutting device such that signals for computation of position and/or orientation may be generated at a hair cutting device  300  or other possible hair cutting devices and sensed at positioning interfaces (such as positioning interfaces  106  as shown in  FIG. 1 ). Embodiments in which some signals are generated and others are sensed on a hair cutting device  300  are also possible. And some sensors and/or positioning interfaces may both generate and sense signals, and in some embodiments may do so simultaneously. 
     Sensors utilized on a hair cutting device  300  may be of various embodiments to sense signals used for computation of position and/or orientation of a hair cutting device  300  in an automated hair cutting system  100 . Hence, sensors  312  may contain antennas, microphones, ultrasound transducers, piezoelectric transducers, accelerometers, gyroscopes, compasses, capacitive transducers, magnetic field sensors, light sensors, photodiodes, cameras, video cameras, passive electronics, active electronics, amplifiers, buffers, wire, waveguides, acoustic pathways, acoustic chambers, or other sensing and/or electronic elements and/or interfacing elements that may be beneficial in generating or sensing positioning signals that may be in use in an automated hair cutting system  100 . Spherically shaped sensors  312  such as those shown in  FIG. 3A  may provide a smooth surface less likely to snag or catch hair. Other possible shapes such as faceted surfaces, hexagonal, octagonal, cylindrical, and other shapes of sensors may also provide benefit for some embodiments. Some embodiments may utilize sensors contained in housings formed from materials through which positioning signals may propagate. Such housings may protect sensors and provide shapes and surfaces that allow hair to flow smoothly over them and avoid snagging or catching hair. In some embodiments, sensors  312  may have a favored direction from which they sense signals more precisely, sense signals at lower power levels, or otherwise favor signals from a certain direction; for such embodiments, some or all sensors  312  may be oriented on hair cutting device  300  so that the favored direction for sensing signals benefits operation of automated hair cutting system  100 . For some such embodiments, sensors  312  may be oriented such that their favored direction is directed toward user  102  and/or positioning device  104  in the course of operation of automated hair cutting system  100 , so that favorable signal reception from user  102  and/or positioning device  104  occurs. And, for some embodiments, a beneficial orientation for some or all of sensors  312  may be so that their favored direction for sensing positioning signals is directed substantial in parallel to handle  308  and in the direction toward cutter head  302  (so that signals coming substantially from the direction of cutter head  302  and propagating toward the sensors  312  are received favorably). 
     Some or all of sensors  312  or other elements of hair cutting device  300  may contain cameras directed to collect images of positioning device  104  and/or user  102  while in operation. Additionally, some or all of sensors  312  or other elements of hair cutting device  300  may contain illumination sources to illuminate positioning device  104  and/or user  102  such that cameras are able to provide a better image over a non-illuminated image. Some embodiments may utilize structured light as an additional aid for the collection and analysis of images or video. Those skilled in the art will recognize that structured light may be utilized to provide a pre-defined pattern of light (such as a grid pattern, stripe pattern, or other pattern) that may be recognized in a camera image or video to aid in analysis of such an image or video. Cameras and illumination sources (including those providing structured light) used in automated hair cutting systems may utilize visible light, infrared light, laser light, or other possible wavelengths, colors, or combinations of colors or types of light. 
     Actuator body  304 , main body  306 , and handle  308  may be constructed together so that they are joined as a single element as shown in  FIG. 3A  or they may be constructed separately or in pieces and fastened, screwed, glued, welded, or otherwise joined together. Actuator body  304 , main body  306 , and handle  308  may be fabricated from wood, plastics, metals, aluminum, stainless steel, combinations of materials, or other suitable materials. Sensors  312  and sensor posts  322  may be fabricated from plastics, wood, aluminum, stainless steel, other metals, electronic materials, semiconductor materials, electronic components, sensor components, silicon, combinations of materials, or other suitable materials. Those skilled in the art will recognize that some embodiments of hair cutting device  300  may benefit from mechanical links between some or all of the sensor posts  322  utilized on such a hair cutting device that may help to mechanically stabilize some or all of the sensor posts. Such mechanical links may include stabilizing members, bands, rings, grids, meshes, or other formations of metals, plastics, wood, or other suitable materials that provide increased rigidity of sensor posts; and may be configured so that hair cutting device  300  may be conveniently gripped and manipulated with substantially little or no interference from these additional mechanical links. 
     Sensor posts  322  may include contoured attachments  332  where sensor posts are coupled onto the cutting device  300 . Contoured attachments  332  may provide a more smoothly contoured surface over which hair may flow smoothly so that snagging or catching hair is made substantially less likely. Other shapes and contour shapes for attachments  322  are also possible. Whereas contoured attachment  332  is embodied in  FIG. 3A  as a smooth curve, faceted attachments, round arcs, variable radius arcs, multiple arcs, and many other shapes of contoured attachments are possible for various embodiments. 
     In  FIG. 3B , hair cutting device  300  is shown held and manipulated by human hand  370  including thumb  372  and fingers  374 . As shown in  FIG. 3B , the embodiment of hair cutting device  300  allows human hand  370  to extend to the region substantially between handle  308  and the sensors  312  proximate thereto. Hand  370  is able to grip hair cutting device  300  substantially near cutter head  302  so that hair cutting device  300  may be maneuvered without blocking sensors  312  needed for determination of the position and/or orientation of hair cutting device  300 . Those skilled in the art will recognize that hair cutting device  300  shown in  FIG. 3B  allows many options for holding and maneuvering hair cutting device  300  without blocking sensors. 
     Embodiments of hair cutting device  300  are also possible in which handle  308  is not present so that main body  306  may be contacted by the palm of hand  370 , with fingers  374  and thumb  372  extending substantially between sensor posts  322 . Embodiments are also possible in which a shortened version of handle  308  is utilized. Those skilled in the art will recognize that some embodiments of a hair cutting device may utilize a handle  308  that extends from main body  306  at an angle relative to the axis of actuator body  304  and main body  306  that handle  308  is shown parallel to in  FIG. 3B . Those skilled in the art will further recognize that some embodiments of a hair cutting device may utilize a handle  308  that extends from main body  306  or from actuator body  304  at a substantially right angle from the orientation of handle  308  as shown in  FIG. 3A  such that handle  308  may extend from main body  306  or from actuator body to the side thereof so that it lies substantially parallel to the direction that the cutter knives of cutter head  302  may be actuated to achieve cutting action. Those skilled in the art will recognize that use of such a side extending handle may allow an actuator inside actuator body  304  to be partially or fully extended into handle  308  and may allow additional flexibility in the types and construction of actuators used to drive cutter head  302 . Cutter head-to-sensor distance D, which measures a distance from cutter head  302  to one of the sensors  312 , will be further explained with regard to  FIG. 4 . 
     In  FIG. 3C , hair cutting device  300  is again shown being held by hand  370 , but closer to handle end  310  than shown in  FIG. 3B . Gripping handle  308  in the fashion shown in  FIG. 3C  may be beneficial for a person using an automated hair cutting device  100  for some hair cutting operations. Hence, the embodiment of hair cutting device  300  as shown provides benefit in allowing multiple ways for it to be gripped for various hair cutting operations. It is noted in  FIG. 3C  that hair cutting device  300  gripped by human hand  370  as shown does not result in any of the sensors of hair cutting device  300  to be blocked from signals propagating toward them from the direction of cutter head  302 . 
     Hair cutting device  300  comprises a central structure including a handle  308 , an actuator body  304 , and a main body  306 . Embodiments are possible in which main body  306 , actuator body  304 , and/or handle  308  are combined as a single structure so that main body  306 , actuator body, and handle  308  may not be distinguishable from each other and are formed to appear and act as a single element. Whether handle  308 , actuator body  304 , and main body  306  are a single structure or multiple structures, and whether other bodies, handles, or other elements are present in some embodiments, hair cutting device  300  offers benefit as it provides one or more sensors  312  supported some distance from a central structure so that the fingers, thumb, and hand of a person grasping hair cutting device  300  may extend substantially between the central structure and the one or more sensors  312 , so that hair cutting device  300  may be grasped without substantially obstructing the one or more sensors  312 . Hair cutting device  300  may also be held and manipulated in other ways. 
       FIG. 4  shows a top view of the head of user  102  including the end of the nose  103  of user  102  to ensure there is no confusion in understanding of the view shown. Positioning device  104  is shown with positioning interfaces  106 , housings  118 , and ear supports  107 . Housings  118  may contain batteries, electronics, interfaces, and other elements beneficial to the operation of positioning device  104 . Head-to-headset distance D2 shows that a separating distance is substantially maintained between the head of user  102  and the tube forming positioning device  104 . Sensors mounted on mounting posts such as sensors  312  in  FIGS. 3A-3C  may catch or be obstructed by elements on positioning device  104 . As such, embodiments of hair cutting devices having sensors mounted similarly to sensors  312  may benefit if cutter head-to-sensor distance D as shown in  FIG. 3B  is greater than head-to-headset distance D2 such that the sensors on the hair cutting device would be somewhat further away from the head of user  102  than a tube or other element of a positioning device during substantially normal operation of automated hair cutting system  100 , thereby reducing interference with a tube or other element of the positioning device. In some embodiments, the sensors may be mounted at different heights relative to one another. Those skilled in the art will recognize that a wide range of positioning devices and hair cutting devices are possible, so a wide array of mechanical constructions are possible to benefit their use in a convenient manner. 
     Referring now to  FIG. 5 , there is shown hair cutting device  500  comprising another embodiment according to the present disclosure. Hair cutting device  500  includes cutter head  530  that may that may be of similar construction to cutter heads shown in this disclosure or may have other construction. Cutter head  530  is mounted to cutter head base  532 . Cutter head base  532  adjoins center body  536 . Center body  536  adjoins main body  504 . Main body  504  may contain an actuator to actuate cutter head  530 . An actuator inside main body  504  may be a solenoid, voice coil motor, stepper motor, linear actuator, rotary actuator, or other possible type of actuator and motion from the actuator may be transferred to cutter head  530  through mechanical connections inside main body  504 , center body  536 , and cutter head base  532 . These mechanical connections may include levers, bearings, gears, axles, hubs, cams, or other possible mechanical functions. The construction of cutter head  530 , cutter head base  532 , center body  536 , and main body  504  as shown in  FIG. 5  may be beneficial for some embodiments as relief areas  534  on each side of center body  536  and between main body  504  and cutter head base  532  may allow a user to more easily maneuver cutter head  530  around ears and other facial features to more easily achieve beneficial results with an automated hair cutting system  100  than may otherwise be possible. 
     Some embodiments of hair cutting device  500  may incorporate a center body  536  that allows cutter head base  532  and cutter head  530  to pivot or articulate relative to main body  504 . A cutter head base  532  and cutter head  530  that may pivot or articulate may enable cutter head  530  to be more easily maneuvered over the scalp of a user receiving a haircut and potentially make it easier to collect hair in cutter head  530 . Those skilled in the art will recognize that actuators, motors, or other elements for driving cutter head  530  may need to be designed to accommodate pivoting or articulation of cutter head  530  and cutter head base  532 . And in some embodiments, it may also be beneficial to incorporate sensors to substantially sense the pivot angle of cutter head  530  relative to main body  504  so that errors that may otherwise occur in computing the positioning and/or orientation of cutter head  530  based on analysis of signals from sensors  508  (and/or from other or additional techniques that may be used for determining position and/or orientation) may be substantially compensated for. 
     Hair cutting device  500  includes sensors  508  mounted on sensor posts  506 . These sensors  508  perform substantially similar functions to the sensors  312  shown on hair cutting device  300  and in other possible hair cutting devices for automated hair cutting systems  100 . Mounting sensors  508  on sensor posts  506  may improve the ability of sensors  508  to receive signals (and in some embodiments, to send signals), as sensors  508  on sensor posts  506  are less likely to be blocked by other parts of hair cutting device  500  or by the hand of a person holding it. Six sensors  508  are shown mounted on four sensor posts  506  in  FIG. 5 , but those skilled in the art will recognize that a wide range of numbers of sensors  508  on a wide range of numbers of sensor posts  506  are possible. The configuration and locations of sensors  508  on sensor posts  506  of the embodiment of hair cutting device  500  provides benefit in that the sensor posts  506  extend from or near to the sides of main body  504  so that the top and bottom of main body  504  are mostly available for a person holding hair cutting device  500  to easily grip and maneuver it. For reference, the sides of main body  504  as shown in  FIG. 5  are parallel to the comb teeth of cutter head  530  and the top and bottom of main body  504  are parallel to the line in which cutter head  530  is actuated. Other configurations of sensor posts  506  and sensors  508  are possible. Those skilled in the art will recognize that additional sensors  508  may be placed on hair cutting device  500  on main body  504 , on center body  536 , on cutter head base  532 , on handle  502 , or possibly on other locations on hair cutting device  500 . It is also noted that sensor posts  506  may be contoured or faceted at their base and possibly along their length to benefit the smooth flow of hair over them and to avoid snagging. Sensor posts  506  may be fabricated from plastics, metals, or other materials. Main body  504 , handle  502 , center body  536 , and cutter head base  532  may be formed from aluminum, other metals, plastics, combinations of materials, or other materials. 
     Hair cutting device  500  includes anti-reflection surface  520  on the top surface of main body  504 . Anti-reflection surface  520  may be a corrugation, texture, or finish formed or generated in the course of fabrication of main body  504 ; or may be a paint, coating, lamination, or other possible finishing layer applied after main body  504  has been formed. Hence, anti-reflection coating  520  may be generated, formed, applied, affixed, or created in many possible fashions. Anti-reflection surface  520  may be of a material, texture, or finish to reduce the likelihood of reflections of the signals that may be used in an automated hair cutting system  100  so that reflecting signals are less likely to generate interference at sensors  508 . For example, if sound or ultrasonic signals are used, anti-reflection coating may be a soft material such as leather, rubber, soft plastics, or other materials that may substantially absorb sound waves and substantially not reflect them. As another example, if light signals are used in an automated hair cutting system, flat black paint or coatings may be applied as an anti-reflection surface to reduce reflections. Anti-reflection surfaces  520  may be applied to hair cutting device  500  on all beneficial surfaces and not only on the top of main body  504  as shown in  FIG. 5 . Also, anti-reflection surfaces  520  may be selected, for some embodiments, to also benefit the ability or comfort of a user in holding and maneuvering hair cutting device  500 . 
     Hair cutting device  500  includes camera  510 , handle  502 , and button  512 . Handle  502  as shown in  FIG. 5  is a long handle that may allow hair cutting device  500  to be easily maneuvered in the fashion that a painter may maneuver a paint brush. Handle  502  in  FIG. 5  is shown extending axially from main body  504  in a direction opposite of center body  536 , but some embodiments may adopt handles extending to the side or in other directions. Camera  510  may be used in support of determining position and/or orientation of hair cutting device  500  and may also be used to allow user  102  to observe their hair on electronic computing device  108  (that is, images or video from camera  510  may be displayed on electronic computing device  108 ) to aid in the ability of user  102  to maneuver and apply hair cutting device  500  and to observe their hair. 
     Button  512  may allow a user  102  to send a variety of signals to hair cutting device  500  including signaling to automated hair cutting system  100  that a reference point has been touched (see Krenik &#39;856 for information on reference points), that actuation of cutter head  530  should cease due to safety concerns, that hair has been collected in cutter head  530  and extension of hair may begin, or other beneficial signals. Button  512  may have varying functionality and be used for different purposes at different times in the course of operation of an automated hair cutting system  100 . Additional buttons, touch sensitive regions, switches, electrical knobs, or other ways to allow a user to control hair cutting device  500  may be added to center body  536 , main body  504 , or handle  502  in various possible embodiments. 
       FIG. 6  shows a perspective internal view of a portion of a hair cutting device similar to the embodiment of  FIG. 5  and shows how a rotary actuator may be used to actuate a cutter head of such a hair cutting device. Numbered elements in  FIG. 6  perform the same functions as like numbered elements in  FIG. 5 . Lever  602  is driven by actuator  600  on axle  604  to drive rounded end  606  in hub  608 . Hub  608  may be mechanically connected to cutter knives  531  so that motion generated by actuator  600  is transferred to cutter knives  531  so that they may be actuated relative to comb teeth  533  of cutter head  530 . Those skilled in the art will recognize that actuator  600  may be a rotary voice coil motor actuator such as those found commonly in hard disk drives and other equipment. Actuator  600  may contain permanent magnets, electro-magnets, and other beneficial elements. Lever  602  may comprise a coil of wire interactive with magnets contained in actuator  600  to effect torque on lever  602  when such a coil is energized with electrical current. Axle  604  may be supported by ball bearings or other suitable forms of bearings. Those skilled in the art will recognize that actuator  600 , lever  602 , axle  604 , rounded end  606 , and hub  608  may be fabricated from suitable materials including suitable combinations of magnetic iron, magnetic metals, aluminum, steel, other metals, plastics, and/or other suitable materials. 
       FIG. 7  shows an exploded view of a cutter head  700  that includes elements suitable for use in a hair cutting device such as hair cutting device  300 , hair cutting device  500  or other possible hair cutting devices. Cutter head  700  comprises a bottom comb  706  including comb teeth  722 , mounting standoffs  724 , and mounting screws  728 . Cutter head  700  also comprises top cutter  704  including cutter knives  720 , guide openings  718 , top surface  752 , and hub  740 . When cutter head  700  is utilized on a hair cutting device such as hair cutting device  500 , mounting screws  728  may affix bottom comb  706  to cutter head base  532  and mounting standoffs  724  may engage guide openings  718  so that lateral force on hub  740  provides guided actuation of top cutter  704  relative to bottom comb  706 . Cutter head  700  may be utilized in multiple ways to collect, extend, and/or cut hair in the course of operation of an automated hair cutting system  100 . Cutter knives  720  and comb teeth  722  may be constructed in the fashion of cutter knives  204  and comb teeth  202  of cutter head  200  shown in  FIG. 2  in some embodiments, or may be of other construction (see Krenik &#39;201 for additional possible embodiments of cutter knives and comb teeth). 
     Lever  742  may perform similar functions to lever  602  in  FIG. 6  or may be of another possible lever design for actuating a cutter head of various possible embodiments of hair cutting devices. Lever  742  includes rounded end  744  that may engaged rounded opening  741  of hub  740  so that actuation of lever  742  may transfer to lateral motion of hub  740 , and so, to lateral motion of top cutter  704 . Lever  742  also comprises cam  746  that has shorter radius near left cam end  750  and longer radius near right cam end  748 . In operation, cam  746  engages top surface  752  of top cutter  704  and provides pressure on top surface  752  to compress top cutter  704  against bottom comb  706  so that cutter knives  720  may intimately engage comb teeth  722 . Those skilled in the art will recognize that rotary actuation of lever  742  over an axle (no axle is shown in  FIG. 7 , but an axle such as axle  604  of  FIG. 6  or other possible axle or pivot may be used in various embodiments) may result in cam  746  providing various levels of pressure against top surface  752  as a function of the rotary position of lever  742  (due to the difference in radius of cam  746  near left cam end  750  and right cam end  748 ). Cam  746  may be configured for various embodiments to provide substantially constant pressure on top surface  752  (in which case it may have substantially consistent radius from left cam end  750  to right cam end  748 ) or may be configured to provide a variety of levels of pressure on top surface  752  as a function of the rotary position of lever  742 . Some embodiments may benefit from substantially higher levels of pressure from cam  746  on top surface  752  when cutter knives  720  are engaging comb teeth  722  for cutting action and substantially lower levels of pressure from cam  746  on top surface  752  during hair collection and extension (so that friction between top cutter  704  and bottom com  706  is reduced during hair collection and extension). Cam  746  may be formed from the same materials as lever  742  and rounded end  744  or may be formed from other materials and be attached or affixed to lever  742 . Some embodiments of cam  746  may benefit from use of compliant materials (such as rubber, plastics, or other compliant materials) that may partially compress under pressure. Compliant materials may also be used to benefit on top surface  752  where compliant materials may be inlaid, embedded, laminated, or otherwise applied for beneficial effect. Those skilled in the art will recognize that a wide range of possible levers, cams, hubs, top cutter constructions, bottom comb constructions, axles, bearings, hard materials, compliant materials, and other materials and constructions may be used to drive a cutter head for a hair cutting device. 
       FIG. 8  is a perspective view of an embodiment of a hair cutting device  800  having sensors mounted on supports around a central structure and with a straight handle extending axially from the central structure. Hair cutting device  800  comprises cutter head  830 , cutter head base  832 , center body  836 , main body  804 , handle  802 , left top support  850 , right top support  852 , lateral support  854 , left sensor  860 , right sensor  862 , bottom support  856 , and bottom sensor  864 . Left sensor  860 , right sensor  862 , and bottom sensor  864  may comprise various configurations and structures, similar to sensors  312  as shown in  FIG. 3A  and discussed in conjunction herein. Left sensor  860 , right sensor  862 , and bottom sensor  864  are shown in  FIG. 8  directed in parallel to handle  802  and toward the direction of cutter head  830 , but may be configured in other directions for some embodiments. The embodiment of hair cutting device  800  in  FIG. 8  utilizes left top support  850  and right top support  852  affixed to main body  804  near the sides of main body  804  and mounted so that the width of main body  804  is not substantially increased so that the resulting width of main body  804 , left top support  850  and right top support  852  is not substantially more than the width of cutter head  830  (however, main body  804  may be sized in various configurations and sizes relative to cutter head  830 ). Accordingly, hair cutting device  800  is configured so that its overall main body  804  width is kept substantially similar to or smaller than the width of cutter head  830  so that it may be more easily maneuvered around a positioning device (such as positioning device  104 ) in the course of providing a haircut. Lateral support  854  is attached to left top support  850  and right top support  852  and supports left sensor  860  and right sensor  862  to be substantially above and wider than main body  804 . Bottom support  856  supports bottom sensor  864  to be below and relatively near to main body  804  (relatively near to main body  804  relative to the distance that left sensor  860  and right sensor  862  are above main body  804 ). 
     The location of sensors of hair cutting device  800  relative to main body  804  as shown in  FIG. 8  may offer benefit from some embodiments. Referring to  FIG. 1 , as hair cutting device  300  is maneuvered to collect, extend and cut hair along the sides, front, and back of the head of user  102 , the teeth of cutter head  302  may generally point in a substantially upward direction so that hair cutting device  300  may generally have elements of positioning device  104  at close proximity to the side of hair cutting device  300  substantially opposite the direction that the teeth of cutter head  300  are pointing. Hence, hair cutting devices such as hair cutting device  800  may have sensors mounted further apart and away from the main body  804  of hair cutting device  800  on the side of hair cutting device  800  from which the teeth of cutter head  830  emanate and point away from, since sensors mounted apart from the main body  804  of a hair cutting device  800  in the direction the cutter head  830  teeth are pointing are less likely to interfere with a positioning device  104 . Further, locating sensors substantially separated from each other and from the main body  804  of a hair cutting device  800  may facilitate a plurality of different positioning signals produced by positioning interfaces  106  that are further separated from each other on a positioning device  104  (providing benefits for reliable computation of the position and/or orientation of a hair cutting device relative to the head of a user). Sensors that are located on a side of a hair cutting device  800  opposite to the direction the teeth of a cutter head are pointing may be kept substantially closer to the central body of such a hair cutting device so that they are less likely to mechanically interfere with a positioning device  104  in the course of operation of an automated hair cutting system  100 . It is also noted that sensors that are located on a side of a hair cutting device opposite to the direction the teeth of a cutter head are pointing may be mounted further back from cutter head  830  than the head-to-headset distance D2 (as shown in  FIG. 4 ), or other suitable dimension for clearance that may be appropriate for various embodiments of positioning devices. Only three sensors are shown in  FIG. 8 , but additional sensors may be mounted on lateral support  854  and additional sensor mounts and sensors may also be mounted on the bottom of main body  804  (in addition to bottom sensor  864 ). Those skilled in the art will recognize that a wide range of sensor supports, sensor locations, shapes of sensor supports, and other configurations of sensors are possible that adhere to the beneficial configuration demonstrated by the embodiment of hair cutting device  800  that utilizes sensors further from a main body  804  to the side of a hair cutting device that cutter head teeth are pointing and closer to a main body  804  on the side opposite that in which cutter head teeth are pointing. 
       FIG. 9  shows a perspective view of an embodiment of a hair cutting device  900  having another configuration of sensors. Cutting device  900  comprises cutter head  930 , cutter head base  932 , center body  936 , main body  904 , handle  902 , left support  906 , right support  908 , left sensor  914 , right sensor  916 , left hinge  910 , and right hinge  912 . Left hinge  910  in left support  906  is shown folded so that left sensor  914  is substantially close to main body  904  for compact storage. Right hinge  912  in right support  908  is shown folded so that right sensor  916  is extended for operation. Those skilled in the art will recognize that various embodiments of sensors, sensor supports, sensor posts, and other structures used to support sensors on hair cutting devices may include the use of hinges, telescoping structures, pivots, collapsible structures, retractable structures, and other suitable structures that may allow sensors to be positioned for operation and also moved to alternative positions for compact or otherwise beneficial positions for storage. In addition, some embodiments of hair cutting devices may utilize support structures for sensors that may be positioned for some hair cutting operations and repositioned to other locations for other hair cutting operations. That is, some sensors on a hair cutting device may be re-positioned in the course of operation of an automated hair cutting system to benefit operation or to avoid interference with a positioning device or user. For such embodiments, the substantially precise location of sensors relative to the body and cutter head of a hair cutting device may be calibrated automatically based on measurements to fixed points on the body or to other sensors, entered manually by a user into an automated hair cutting system (for example, one of perhaps only a few possible positions for a given sensor might be manually entered into electronic computing device  108 ), determined through the use of encoders or other automated elements present in the various hinges or other structures used to support and position sensors, or through other possible techniques. The embodiment of hair cutting device  900  shown includes only two sensors, but those skilled in the art will recognize that additional embodiments with other numbers of sensors are possible. 
       FIG. 10  shows a partial view of a hair cutting device  1000  having yet another sensor configuration. Cutting device  1000  comprises cutter head  1030 , main body  1004 , handle  1002  (only partially shown in the figure), sensor  1010 , sensor opening  1012 , sensor post  1014 , acoustic pathway  1015 , circuit board  1020 , and microphone  1022 . Hair cutting device  1000  provides an example of a sensor post  1014  that includes a hollow center, tube, tunnel, or other formation to create an acoustic pathway  1015  from an opening  1012  in sensor  1010 . The embodiment of hair cutting device  1000  allows an acoustic positioning signal to be channeled from the location of sensor  1010  through sensor opening  1012  and acoustic pathway  1015  to a microphone  1022  mounted on a circuit board  1020  inside main body  1004 . Locating microphone  1022  inside main body  1004 , may eliminate the need for electrical connections through sensor post  1014  to sensor  1010 . Use of an acoustic pathway  1015  inside sensor posts on a hair cutting device may allow embodiments of automated hair cutting systems using audible sound, ultrasound, or other acoustic positioning signals to be more easily manufactured. Those skilled in the art will recognize that similar embodiments using waveguides, optical pathways, or other structures that allow positioning signals to be directed to a sensing device inside main body  1004  or other element of a hair cutting device may provide similar benefits for other types of positioning signals. Those skilled in the art will also recognize that compensation of the propagation time of a signal through acoustic pathway  1015  (or other structure to allow directed signal propagation) may be done in conventional ways in the course of computation of position and/or orientation of a hair cutting device as the dimensions of acoustic pathway  1015  and the propagation characteristics of signals through acoustic pathway  1015  may be known. In some embodiments, sensor opening  1012  may be protected with a grill, mesh, filter, or other structure to reduce the likelihood that dirt, cut hair, or other contaminants may obstruct sensor opening  1012 . 
       FIG. 11  shows an embodiment of a manual hair cutting device  1100  that does not make use of position sensors or other automated functions. Manual hair cutting device  1100  comprises cutter head  1130 , cutter head base  1132 , center body  1136 , main body  1104 , handle  1102 , camera  1110 , relief areas  1134  and button  1112 . Some embodiments of manual hair cutting device  1100  may not include sensors or sensor posts. Manual hair cutting device  1100  may be designed to be used manually, so cutter head  1130  may be actuated due to a voice command, button press of button  1112  (or other buttons that may be added to an embodiment in  FIG. 11 ), or other manual signal from a person using manual hair cutting device  1100 . A camera  1110  may be included on manual hair cutting device  1100  as some embodiments of manual hair cutting device  1100  may include a wired or wireless link to an electronic display or electronic computing device (such as electronic computing device  108  shown in  FIG. 1 ) so that images and/or video from camera  1110  may be displayed and viewed as a user is cutting their hair. It is also noted that hair cutting devices for automated hair cutting system  100  (such as hair cutting device  500  of  FIG. 5 ) may also be used, at times, in a manual mode in the fashion of hair cutting device  1100  of  FIG. 11 . That is, while hair cutting device  500  includes elements for operation in an automated hair cutting system  100 , manual modes of operation may also be possible for some embodiments and either manual or automated operation may be preferred for some hair cutting operations, user preferences, or other considerations. 
       FIG. 12  shows an exploded view of a shaving accessory  1210  and hair cutting device  800 . The embodiment of hair cutting device  800  shown in  FIG. 12  includes a first electrical plug  1202  and a second electrical plug  1204 . First electrical plug  1202  and a second electrical plug  1204  may provide access to electrical power for shaving accessory  1210  when first electrical lead  1212  and second electrical lead  1214  are mated to first electrical plug  1202  and second electrical plug  1204 , respectively, when shaving accessory  1210  is mounted to hair cutting device  800 . Power provided by first electrical plug  1202  and second electrical plug  1204  to shaving accessory may include power and ground sources, power and common, DC (direct current) power and ground, positive and negative DC power sources, AC (alternating current) and ground, multiple phases of AC power, or any other configuration of power, ground, and other possible power sources suitable for powering an accessory. While the embodiment of  FIG. 12  shows only a first electrical plug  1202  and a second electrical plug  1204 , those skilled in the art will recognize that embodiments including additional electrical plugs and leads are possible. Embodiments with only one electrical plug and electrical lead may also be provided if a ground connection (or other secondary electrical connection) may be established through other mating conductive surfaces when shaving accessory  1210  is mounted to hair cutting device  800 . Those skilled in the art will recognize that in addition to providing power, electrical connections through plugs and leads may be established between shaving accessory  1210  and hair cutting device  800  that allow hair cutting device  800  to control shaving accessory  1210 . Such controls may include turning on and off or controlling the speed of a motor or motors inside shaving accessory  1210  or providing other beneficial control signals. Shaving accessory  1210  may also provide information or controls to hair cutting device  800  such as indications of over-heating of a motor inside shaving accessory  1210 , indications of fault conditions, indications of motor speed, or other useful information. And while the embodiment of  FIG. 12  shows conductive electrical connections between shaving accessory  1210  and hair cutting device  800 , those skilled in the art will recognize that inductive connections through magnetic coils, wireless interfaces, or other suitable techniques may be utilized to transfer power and signals between a hair cutting device and a shaving accessory. 
     Shaving accessory  1210  may contact the base of cutter head  830  and may also contact other portions of cutter head  830  and cutter head base  832 . Inside surface  1218  of shaving accessory  1210 , for example, may contact cutter head  830  and side panel  1220  of shaving accessory  1210  may contact the side of cutter head  830  and/or cutter head base  832 . Hair cutting device  800  may sense when shaving accessory  1210  is attached (through sensing and analysis of the electrical connections already explained or use of other sensors, switches, proximity sensors, or other techniques) and may inactivate cutter head  830  so that shaving accessory  1210  may contact cutter head  830  without concern regarding actuation of the cutter knives of cutter head  830 . Shaving accessory  1210  may contain one or more electric motors or actuators to drive one or more blades behind shaving screen  1216 . Hairs may enter the openings of shaving screen  1216  and extend inside shaving accessory  1210  so that moving blades may cut them (in a manner well-established by the many electric shavers now commonly available). Shaving accessory may be mechanically attached to hair cutting device  800  with clips, pins, screws, cams, Velcro, magnets, snaps, or other suitable techniques. In addition to attaching to a cutter head as shown in  FIG. 12 , shaving accessories or other accessories may be attached to a hair cutting device at other locations or in other configurations. 
     The embodiment of a shaving accessory  1210  mounted to a hair cutting device  800  as shown in  FIG. 12  may allow the positioning and control benefits of an automated hair cutting system  100  to be extended to shaving and may allow a battery or other power source in a hair cutting device  800  to be utilized to power a shaving accessory. Those skilled in the art will recognize that additional accessories for other purposes besides shaving may benefit from similar application to the embodiment of  FIG. 12 . Accessories used for the purpose of trimming, shaving, thinning, texturing, detailing, or otherwise cutting or styling hair may be applied to a hair cutting device  800  in the manner shown in  FIG. 12 . Accessories used for purposes besides cutting, shaving, or trimming hair may also be applied to hair cutting devices. For example, make-up applicators, face paint applicators, lipstick applicators, facial massagers, cosmetics applicators, eye make-up applicators, hair dye applicators, curling irons, hair shaping/styling accessories, and many other possible accessories may benefit from the ability to attach to and be powered and controlled by a hair cutting device in an automated hair cutting system. Those skilled in the art will recognize that unpowered accessories may also be attached to a hair cutting device so that they may also benefit from the position and/or orientation sensing and control capability of an automated hair cutting system. Examples of such unpowered accessories include safety razors, straight razors, unpowered face paint or makeup applicators, unpowered hair dye or hair highlights applicators, or other possible accessories. 
     Position sensors, cameras, transducers, or other elements for generating or sensing positioning signals on a hair cutting device may be mounted in improved locations that allow persons using an automated hair cutting system more options for how to hold and maneuver a hair cutting device. Such improved locations and mounts may also allow position sensors, cameras, transducers, or other elements for generating or sensing positioning signals to be substantially less likely to be blocked so that they are more effective in providing signals that may be used to determine the position and/or orientation of a hair cutting device. Mounting posts and structures may be contoured so they are less likely to snag hair. Hair cutting devices may have sensor supporting structures that are larger so that sensors may be more broadly spaced on the side of a hair cutting device from which cutter head teeth emanate and point away from, and sensor supporting structures that are smaller so that they interfere less with a positioning device on the side of the hair cutting device opposite the direction that cutter head teeth point. Improved balance of hair cutting devices may improve user comfort and maneuverability. Improved balance may be achieved by preferred location of batteries, electronics, and other internal elements of a hair cutting device, and may also include use of ballast weights. 
     Hair cutting devices may better interoperate with specific positioning devices and may have physical dimensions and placement of sensors and supporting structures that are configured to minimize undesired interference. Hair cutting devices may include relief areas between a cutter head supporting structure and a main body so that a cutter head may be more easily manipulated around ears and other features of a user&#39;s head. Actuators and cutter head drive mechanisms may be designed to allow such relief areas and may provide variable forces on cutter heads to reduce friction and power levels used during some phases of cutter head operation and provide reliable cutting action in other phases of cutter head operation. Structures supporting sensors on hair cutting devices may be folded for compact storage or may be adjusted in the course of operation. Structures supporting sensors may provide passive channels or guides so that positioning signals may propagate around or inside a supporting structure to sensing electronics located some distance from the point where a positioning signal is actually sensed. And electrically powered or unpowered accessories, such as a shaving accessory, may be mounted to and possibly be powered and/or controlled by a hair cutting device. 
     Although the present disclosure has been described in detail, those skilled in the pertinent art should understand that they can make various changes, substitutions and alterations herein without departing from the spirit and scope of the disclosure in its broadest form.