Patent Publication Number: US-2023144759-A1

Title: Controlling devices using facial movements

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims priority to U.S. Provisional Patent Application No. 62/882,006, filed on Aug. 2, 2019, entitled “METHOD FOR FACIAL EXPRESSION TRACKING,” the disclosure of which is incorporated herein by reference in its entirety. 
    
    
     BACKGROUND 
     Technical Field 
     Embodiments of the disclosed subject matter generally relate to systems and methods for controlling devices, including power-driven mobility devices and devices other than power-driven mobility devices, using facial movements. 
     Discussion of the Background 
     Quadriplegia is a condition in which a person does not have the ability to control their arms and legs, which makes it difficult for people with this condition to live independently. These types of injuries typically occur to middle-age adults, who accordingly require lifetime solutions to allow them to interact with the world. 
     Due to the loss of ability to control their arms and legs, quadriplegics cannot use conventional assistive technology (i.e., power-wheel chairs operated using a joystick) to move around. Various solutions have been proposed to address this issue, including spin-n-puff, head or chin joysticks, brain-machine interfaces using neural detectors to interpret action commands, camera-based systems for facial and gaze detection, voice control, and tongue detection. These solutions, however, offer limited action commands, require bulky and invasive equipment (e.g., bulky transducers attached to sensitive organs), are expensive, or require significant computational power. Some of these solutions also require continuous attention by the patient to prevent the patient from moving and talking at the same time. 
     Some quadriplegics have more severe injuries (i.e., C1 and C2 injuries), and suffer from difficulty speaking, as well as difficulty moving their head and neck. For these people, the only remaining solutions are using cameras, tongue control, or neural detectors. These technologies have so far been implemented with very limited action commands. Specifically, the action commands are limited to those for controlling the power-driven mobility device itself. These solutions thus do not provide any ability to control devices other than the power-driven mobility device itself, and accordingly these solutions fail to provide quadriplegics with tools for living independently. 
     WO 2020/144598 discloses a system with magnetic skin tags and magnetic sensors that determine changes in magnetic fields generated by the magnetic skin tags. There is no discussion of how to use the system to address issues particular to quadriplegics. 
     Accordingly, there is a need for a solution for quadriplegics to control movement of a power-driven mobility device, as well as controlling devices other than power-driven mobility devices, without incurring high costs, requiring large computational power, and bulky and invasive equipment. 
     SUMMARY 
     According to an embodiment, there is a system for controlling at least one device. The system includes a pair of glasses comprising a glasses frame. A plurality of magnetic sensors, a processor coupled to the plurality of magnetic sensors, and a wireless communication transmitter coupled to the processor are arranged on or in the glasses frame. A plurality of magnetic skins tags are arranged on a human face. The plurality of magnetic sensors sense movement of at least one of the plurality of magnetic skin tags and transmit a signal corresponding to the sensed movement to the processor. The processor, responsive to receipt of the signal corresponding to the sensed movement, transmits a signal for controlling the at least one device via the wireless communication transmitter to a processor of a power-driven mobility device. 
     According to an embodiment, there is a method for controlling at least one device. At least one of a plurality of magnetic sensors arranged on a glasses frame sense a change in a magnetic field due to movement of at least one of a plurality of magnetic skin tags arranged on a human face. A wireless communication transmitter, coupled to or arranged in the glasses frame, transmits a signal corresponding to the sensed change in the magnetic field to a processor of a power-driven mobility device via a wireless communication transceiver of the power-driven mobility device. The processor of the power-driven mobility device determines a command corresponding to the signal. The processor of the power-driven mobility device controls the device based on the determined command. 
     According to an embodiment, there is a system for controlling a power-driven mobility device and at least one device. The system includes a pair of glasses comprising a glasses frame, a plurality of magnetic sensors, a processor coupled to the plurality of magnetic sensors, and a wireless communication transmitter coupled to the processor. A plurality of magnetic skins tags are arranged on a human face. The plurality of magnetic sensors are configured to sense movement of at least one of the plurality of magnetic skin tags and transmit a signal corresponding to the sensed movement to the processor. The system also includes a power-driven mobility device comprising a motor, a processor, an interface coupled to the processor and motor, a wireless communication transceiver coupled to the processor, and a wireless communication transmitter coupled to the processor. The processor of the pair of glasses, responsive to receipt of the signal corresponding to the sensed movement, transmits a signal for controlling the power-driven mobility device or the at least one device to the processor of a power-driven mobility device. The at least one device comprises a wireless receiver configured to wirelessly communicate with the wireless communication transmitter of the power-driven mobility device. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate one or more embodiments and, together with the description, explain these embodiments. In the drawings: 
         FIG.  1 A  is a schematic diagram of a pair of glasses according to embodiments; 
         FIG.  1 B  is an illustration of a pair of glasses and magnetic skin tags on a human face according to embodiments; 
         FIG.  10    is a schematic illustration of circuitry of a pair of glasses according to embodiments; 
         FIG.  2 A  is a schematic diagram of a power-driven mobility device according to embodiments; 
         FIG.  2 B  is a schematic diagram of circuitry of a power-driven mobility device according to embodiments; 
         FIG.  3    is a schematic diagram of a system for controlling a device according to embodiments; 
         FIGS.  4 A and  4 B  are flowcharts of a method for controlling at least one device according to embodiments; and 
         FIG.  5    illustrates the changes in magnetic fields measured by magnetic sensors responsive to moving different portions of a human face. 
     
    
    
     DETAILED DESCRIPTION 
     The following description of the exemplary embodiments refers to the accompanying drawings. The same reference numbers in different drawings identify the same or similar elements. The following detailed description does not limit the invention. Instead, the scope of the invention is defined by the appended claims. The following embodiments are discussed, for simplicity, with regard to the terminology and structure of assistive technology. 
     Reference throughout the specification to “one embodiment” or “an embodiment” means that a particular feature, structure or characteristic described in connection with an embodiment is included in at least one embodiment of the subject matter disclosed. Thus, the appearance of the phrases “in one embodiment” or “in an embodiment” in various places throughout the specification is not necessarily referring to the same embodiment. Further, the particular features, structures or characteristics may be combined in any suitable manner in one or more embodiments. 
     A system for controlling at least one device will now be described in connection with  FIGS.  1 - 3   , where  FIGS.  1 A- 1 C  illustrate components worn on a human face,  FIGS.  2 A and  2 B  illustrate a power-driven mobility device, and  FIG.  3    illustrates a device other than a power-driven mobility device that can be controlled by facial movements (the device of  FIG.  3    is also referred to herein as the controlled device and the further device). The system includes a pair of glasses  105 , which comprises a glasses frame  110 . A plurality of magnetic sensors  115   1 - 115   x , a processor  120  coupled to the plurality of magnetic sensors  115   1 - 115   x , and a wireless communication transmitter  125  coupled to the processor  120  are arranged on or in the glasses frame  110 . As illustrated in  FIG.  1 B , a plurality of magnetic skins tags  130   1 - 130   x  are arranged on a human face  135 . The plurality of magnetic sensors  115   1 - 115   x  sense movement of at least one of the plurality of magnetic skin tags  130   1 - 130   x  and transmit a signal corresponding to the sensed movement to the processor  120 . The processor  120 , responsive to receipt of the signal corresponding to the sensed movement, transmits a signal for controlling the at least one device  205  or  300  via the wireless communication transmitter  125  to a processor  210  of a power-driven mobility device  205 . In embodiments, the wireless communication transmitter  125  can be a wireless communication transceiver capable of transmitting and receiving wireless signals. 
     The plurality of magnetic skin tags  130   1 - 130   x  can be colored to match a user&#39;s skin tone, can be colored to be easily visible and identifiable, or can be colored in a manner that would be considered fashionable by the user. The plurality of magnetic skin tags  130   1 - 130   x  can be secured to the face using any technique, such as using a bio-compatible adhesive (e.g., an adhesive that allows the underlying skin to breathe), a petroleum jelly, or any other substance that can secure the plurality of magnetic skin tags  130   1 - 130   x  to a human face that will not irritate the user&#39;s skins when worn over a long period of time, such as hours, days, or weeks. Although  FIG.  1 B  illustrates the plurality of magnetic skin tags  130   1 - 130   x  as exhibiting an oval shape, the plurality of magnetic skin tags  130   1 - 130   x  can have any shape, and in some implementations can be designed to spell out words, numbers of letters. In other words, the actual shape of the plurality of magnetic skin tags  130   1 - 130   x  is immaterial so long as the plurality of magnetic skin tags  130   1 - 130   x  produce a sufficient magnetic field, the change of which can be sensed by the plurality of magnetic sensors  115   1 - 115   x . 
     Further, although  FIGS.  1 A and  1 B  respectively illustrate a particular arrangement of the magnetic sensors  115   1 - 115   x  and the magnetic skin tags  130   1 - 130   x , other arrangements are possible. In the other arrangements, there should be at least a 1-1 relationship between the number of magnetic sensors  115   1 - 115   x  and the number of magnetic skin tags  130   1 - 130   x  (e.g., there can be more than one magnetic sensor to sense changes in magnetic fields of one magnetic skin tag). Additionally, although  FIGS.  1 A and  1 B  respectively illustrate three magnetic sensors  115   1 - 115   x  and three magnetic skin tags  130   1 - 130   x  a greater number or fewer number of magnetic sensors and magnetic skin tags can be employed. Fewer magnetic sensors and magnetic skin tags reduces the number of possible commands and more magnetic sensors and magnetic skin tags increase the number of available commands. Accordingly, the location and number of magnetic skin tags and magnetic sensors can be customized to the needs of the user. For example, if the user does not have much control over his/her nose, then only the forehead magnetic skin tag and a corresponding magnetic sensor can be employed, or alternatively another location on the user&#39;s face can be used for the magnetic skin tags that are illustrated as being placed on the user&#39;s nose. 
     Referring specifically to  FIGS.  1 A and  1 C , the processor  120  and wireless communication transmitter  125  can be part of the same component or can be separate components. A non-limiting example of a combined processor  120  and wireless communication transmitter  125  is a Bluno Nano chip, which is an Arduino Nano chip with Bluetooth 4.0 functionality. The glasses  105  also include a power source  145 , such as a battery. Alternatively, or additionally, the power source  145  can be any other type of power source, such as a fuel cell, solar panel, etc. Although  FIG.  1 A  illustrates the processor  120 , wireless communication transceiver  125 , and power source  145  being attached to the frame  110 , these components can be integrated into the frame  110 . 
     As illustrated in  FIG.  1 C , the plurality of magnetic sensors  115   1 - 115   x  can be coupled to the processor  120  via a multiplexer  140  and provides measurements of changes in magnetic field in the form of a voltage that corresponds to the magnitude of the change in magnetic field. In a non-limiting example, the multiplexer  140  can be, for example, a PCA9548 octal bidirectional translating switch. It should be recognized, however, that, depending on the processor  120  employed, the multiplexer  140  can be omitted. In the illustrated embodiment, the upper line between the multiplexer  140  and the processor  120 /wireless communication transmitter  125  is a data line (e.g., an SCL/SDA line) and the lower line is a power line for conveying power from the battery  145  to the multiplexer  140 . Further, the upper line between the magnetic sensors  115   1 - 115   x  is a power line for conveying power from the battery  145  to the magnetic sensors  115   1 - 115   x  and the remaining lines are data lines (e.g., SCL/SDA lines). In one embodiment, the magnetic sensors are BM1422AGMV 3-axis digital magnetometers, which as discussed in more detail below, are configured to sense changes in magnetic field in only one of the three axes. However, other types of magnetic sensors can be employed. Further, the magnetic sensors  115   1 - 115   x , such as the BM1422AGMV 3-axis digital magnetometers, can be configured to sense changes in magnetic fields in two or all three axes. 
     Referring now to  FIGS.  2 A and  2 B , the power-driven mobility device  205  includes a motor (not visible in the figures) operatively coupled to at least one wheel  220  of the power-driven mobility device  205  to control movement of the power-driven mobility device  205 . Although  FIG.  2 A  illustrates a wheelchair as the power-driven mobility device, the disclosed embodiments can be employed with other types of power-driven mobility devices, such as electric scooters, golf carts, Segways®, and the like. Thus, consistent with the usage in the art, the term power-driven mobility device should be understood as any mobility device powered by batteries, fuel, or other engines that is used by individuals with mobility disabilities for purposes of locomotion. 
     As will be recognized by those skilled in the art, a power-driven mobility device can include a single motor coupled to two or more wheels or a separate motor for each wheel, and in many commercial wheelchairs (as well as electric scooters), motors are coupled to either the front or rear set of wheels (typically the motor is coupled to the larger of the front and rear set of wheels). The power-driven mobility device  205  also includes a wireless communication transceiver  225  coupled to the processor  210 . An interface  230  is coupled to the processor  210  and motor. The processor  210  is configured to control movement of the power-driven mobility device  205  using interface  230  based on the signal for controlling the device transmitted from the pair of glasses  105  to the wireless communication transceiver  235  of the power-driven mobility device  205 . In one embodiment, which can be used to retrofit an existing power-driven mobility device, the interface  230  is coupled to the controller of the power-driven mobility device&#39;s motor. In another embodiment, which can be used for a power-driven mobility device manufactured with the disclosed equipment, the interface is also the controller of the power-driven mobility device&#39;s motor. 
     Referring now to  FIG.  2 B , the components of the power-driven mobility device  205  include the processor  210  and wireless communication transceiver  225 , which are coupled between a further wireless communication transceiver  235  and digital-to-analog converters  240 . In an embodiment, wireless communication transceiver  225  of the power-driven mobility device  205  communicates with the wireless communication transmitter  125  of the pair of glasses  105  using radio frequencies and the power-driven mobility device  205  communicates with a further device  300  (see  FIG.  3   ) using line-of-sight communications, such as using visible, near-infrared, or infrared frequencies. If the processor  210  includes digital-to-analog conversion circuitry, the digital-to-analog converters  240  can be omitted. In the illustrated embodiment, the wireless communication transceiver  235  can include a transmitter  235 A and a receiver  235 B. 
     In one non-limiting implementation, the further wireless communication transceiver can communicate using infrared frequencies in the 38 KHz frequency band. In the embodiment illustrated in  FIG.  2 B , the upper line is a data line to the receiver  235 B, the lower line is a data line to the transmitter  235 A and the middle line is a power line. Similar to the circuitry of the glasses  105 , the processor  210  and wireless communication transceiver  225  can be part of the same component or can be separate components, and in a combined implementation a Bluno Nano chip can perform the required functionality of the two components. In the illustrated embodiment, the digital-to-analog converter  240  includes one analog-to-digital converter  240 A for providing commands for controlling forward and backward movement (corresponding to forward and backward movement of the joystick on the power-driven mobility device) and a second analog-to-digital converter  240 B for providing commands for controlling left and right movement (corresponding to left and right movement of the joystick on the power-driven mobility device). Depending upon implementation, a single analog-to-digital converter can be employed. 
       FIG.  3    is a schematic diagram of a system for controlling a device according to embodiments. This controlled device (also referred to herein as the further device) is a device other than the power-driven mobility device, including, but not limited to, a light, a door, a window, an elevator, a television, a set-top box, a pedestrian traffic light, a phone, curtains, doors, or a computer. In other words, the controlled device can be any device requiring physical actions/manipulation that cannot be performed by quadriplegics but can be performed by persons without quadriplegia. The controlled device includes a wireless communication receiver  305  coupled to a processor  310 . Similar to the wireless communication transceiver  225 , the wireless communication receiver  305  can be a transceiver that includes a transmitter  305 A and a receiver  305 B, and can communicate, for example, using line-of-sight communications with infrared frequencies, such as the 38 KHz band. However, other frequencies and line-of-sight communication technologies can be used, as desired. Processor  310  is coupled to an interface  315  to the controlled device  320 . The interface  315  can include, for example, a digital-to-analog converter, relay, etc. for converting control signals from processor  310  into a format suitable for controlled device  320 . Alternatively, the controlled device  320  can be manufactured to operate with the system, in which case the transceiver and processor of the controlled device  320  itself can be configured in the manner described herein to control the controlled device  320 . 
     In the embodiment illustrated in  FIG.  3   , the upper line between the wireless communication receiver  305  and processor  310  is a data line to the receiver  305 B, the lower line is a data line to the transmitter  305 A, and the middle line is a power line. Further, the processor  310  provides power to both the interface  315  and the controlled device  320  using the upper line in  FIG.  3   . The lower line between the processor  310  and the interface  315  provides data commands from processor  310  to interface  315 , and the lower line between the interface  315  and the controlled device  320  provides data commands from the interface  315  to the controlled device  320 . 
     A method for controlling at least one device  205  and/or  300  will now be described in connection with  FIG.  4 A . At least one of a plurality of magnetic sensors  115   1 - 115   x  arranged on a glasses frame  110  senses a change in a magnetic field due to movement of at least one of a plurality of magnetic skin tags  130   1 - 130   x  arranged on a human face  135  (step  405 ). The changes in magnetic field are conveyed by the plurality of magnetic skin tags  130   1 - 130   x  in the form of a voltage having a magnitude corresponding to the magnitude of the change in the magnetic field. A wireless communication transmitter  125  coupled to or arranged in the glasses frame  110  transmits a signal corresponding to the sensed change in the magnetic field to a processor  210  of a power-driven mobility device  205  via a wireless communication transceiver  225  of the power-driven mobility device  205  (step  410 ). The processor  210  of the power-driven mobility device  205  determines a command corresponding to the signal (step  415 ). The processor  210  of the power-driven mobility device  205  controls the device  205  and/or  300  based on the determined command (step  465 ). 
     Additional details for how the processor  210  of the power-driven mobility device  205  determines a command corresponding to the received signal will now be described in connection with  FIG.  4 B . As will be described below, this method involves the use of a switch command for switching between commands directed to movement of the power-driven mobility device  205  and commands for controlling the further device  300 , which is a device other than the power-driven mobility device  205 . This is particularly advantageous because it allows the use of the same facial movements to send different commands to the power-driven mobility device  205  and device  300 , depending upon the control mode. 
     When the processor  210  of the power-driven mobility device  205  receives a command, it determines whether the command is a switch command (step  420 ). If the command is not a switch command (“No” path out of decision step  420 ), the processor  210  determines whether the command is a command for the power-driven mobility device (step  425 ). This determination is based on which control mode is currently active, the control mode being selected by a switch command and/or being defaulted to controlling the power-driven mobility device  205  or the device  300  upon initial powering on. If the command is not for the power-driven mobility device  205  (“No” path out of decision step  425 ), then the power-driven mobility device  205  controls the device  300 , which is also referred to herein as the further device (step  430 ). This involves the processor  210  sending the command, determined based upon the signal transmitted from the glasses  105 , via wireless communication transmitter  235  (which can be a transceiver), which passes the command to processor  310  for controlling device  320 . 
     If, however, the command is for the power-driven mobility device (“Yes” path out of decision step  425 ), then the processor  210  of the power-driven mobility device  205  controls movement of the power-driven mobility device  205  (step  435 ). Again, this involves the processor  210  sending commands to the interface  230 , which can include passing the commands through the digital-to-analog converter  240 . 
     Returning to step  420 , if the processor  210  determines that the received command is a switch command (“Yes” path out of decision step  420 ), then the processor  210  determines whether the switch is a switch from controlling the power-driven mobility device  205  to controlling the further device  300  (step  440 ). If the switch is a switch from controlling the device  300  to controlling the power-driven mobility device  205  (“No” path out of decision step  440 ), then processor  210  switches to power-driven mobility device command mode (step  445 ) and interprets any future commands, other than a switch command, as being directed to controlling movement of the power-driven mobility device  205 . If the switch is a switch from controlling movement of the power-driven mobility device to controlling the device  300  (“Yes” path out of decision step  440 ), then the processor  210 , using wireless communication transmitter  235 , searches for the further device  300  (step  450 ) and the processor  210  determines whether the further device  300  is found (step  455 ). If the further device  300  is not found (“No” path out of decision step  455 ), the processor  210  continues to search for the further device  300  (step  450 ). A time-out value can be defined, if desired, to revert back to the mode for controlling the power-driven mobility device  205  if the further device  300  is not found at the expiration of the time-out value. 
     If, however, the processor  210  determines that the further device  300  is found (“Yes” path out of decision step  455 ), then the processor  210  switches to a mode for controlling the further device  300  (step  460 ) and interprets any further commands as being used to control the further device  300 . It should be recognized that the switch from the mode controlling movement of the power-driven mobility device  205  to controlling the further device  300  does not occur until the further device  300  is found. Thus, any commands that are received prior to this time (i.e., while the processor  210  searches for the further device  300 ), will be interpreted as commands for controlling movement of the power-driven mobility device  205 . It should be recognized, however, that the switch in command modes to controlling the further device  300  can occur immediately in response to receipt of the switch command, if so desired. 
     The delay in the mode switch from controlling the power-driven mobility device  205  to controlling the further device  300  until the further device  300  is particularly advantageous when the power-driven mobility device  205  and further device  300  communicate using line-of-sight communications, such as visible, near-infrared, or infrared frequencies. Specifically, it allows a person to continue to send commands for moving the power-driven mobility device  205  so that the wireless communication transceiver  235  of the power-driven mobility device  205  is aligned with the corresponding wireless communication receiver  305  of the further device  300 . 
     The use of line-of-sight for communicating between the power-driven mobility device  205  and further device  300  is particularly advantageous over the use of radio frequencies because line-of-sight communications do not require the robust initialization of the communication connection typically required by most standardized wireless communication techniques that use radio frequencies. Specifically, the line-of-sight communications do not necessarily involve, but could involve if desired, the initial handshaking between devices, as well as the authorization and authentication signaling required by typical radio frequency communication techniques. In contrast, the power-driven mobility device  205  and the glasses  105  are intended to maintain a long-term connection, and thus the additional time for the initial handshaking between the power-driven mobility device  205  and the glasses  105  is not considered to be as much of a concern as with the communication between the power-driven mobility device  205  and the controlled device  300 . Further, because the power-driven mobility device  205  acts as a gateway and can be moved based on commands provided by the glasses  105 , the additional authorization and authentication of radio frequency communication techniques ensures that movement of the power-driven mobility device  205  is only performed in response to a person authorized to issue such commands. 
     Employing the power-driven mobility device  205  as a gateway is also particularly advantageous because a larger processor can be incorporated into the power-driven mobility device  205  without being obtrusive compared to the processor on/in the glasses  105 . Further, this reduces the battery consumption of the electronics of the glasses  105 , and allows the glasses  105  to operate all of its electronics using a relatively small battery. Thus, the logic for correlating the changes in magnetic fields into commands for controlling the power-driven mobility device  205  and controlled device  300  can be incorporated into the processor  210  of the power-driven mobility device  205 . This correlation can be achieved using any number of techniques, including, for example, using a lookup table correlating measured changes in magnetic fields to commands. The disclosed embodiments can employ any communication technique using radio frequencies. However, it is advantageous from a power consumption perspective to employ a short-range radio technology, such as Bluetooth, including Bluetooth Low Energy (BLE), or Wi-Fi. 
     Now that an overview of the system and method have been presented, additional details of the structure and operation of the system are now presented. Returning to  FIG.  1 A , in the illustrated embodiment the plurality of magnetic sensors  115   1 - 115   x  include a magnetic sensor  115   1  arranged on the bridge of the glasses  105 , a magnetic sensor  115   2  arranged on the lower left portion of the frames (approximately below the left side of the bridge) and a magnetic sensor  115   3  arranged on the lower right portion of the frames (approximately below the right side of the bridge). An additional magnetic sensor  115   x  is arranged in the area of one of the hinges of the glasses  105 , which is used as a reference sensor to measure external magnetic noise (e.g., the Earth&#39;s magnetic field) so that this noise can be canceled from the magnetic fields sensed from the other magnetic sensors  115   1 - 115   3 . Other locations for the additional magnetic sensor  115   x  is at the bottom-left or bottom-right portions of the glasses  105 , or any other portion of the glasses  105  that are as far from the intended location of the magnetic skin tags  103   1 - 130   x . 
     Further, as illustrated in  FIG.  1 B  the plurality of magnetic skins tags  130   1 - 130   x  includes a magnetic skin tag  130   1  arranged in the glabella of the human face  135 , a magnetic skin tag  130   2  arranged on the left side of the nose of the human face  135 , and a magnetic skin tag  130   x  arranged on the right side of the nose of the human face  135 . 
     Although the magnetic skin tags  130   1 - 130   x  and magnetic sensors  115   1 - 115   x  can be arranged in different locations than the arrangement illustrated in  FIG.  1 B , this particular arrangement was found to be optimal for avoiding accidental activations (i.e., incorrectly interpreting a facial movement as a command), while still allowing for a particularly easy way to send commands. Specifically, it was found that eyebrow and nose movement is less likely accidentally occur than movement of other locations of the face, such as the cheeks, which move when talking and laughing. In order to further reduce accidental activations, in one embodiment commands require movement of both eyebrows in the same direction, a facial movement that is unlikely to occur accidentally. Accidental activations can also be reduced by employing a threshold for the change in magnetic field to qualify as being an intended gesture. 
     It should be recognized that the magnetic sensors  115   1 - 115   x  should be arranged in a predefined relationship with respect to the magnetic skin tags  130   1 - 130   x  in order to properly interpret the change in magnetic fields due to facial movements. In a non-limiting embodiment, the magnetic skin tags  130   1 - 130   x  are magnetized along the z-axis (which is in the vertical direction when a person&#39;s head is level with the earth) and should be arranged either above or below the magnetic sensors  115   1 - 115   x . Similarly, the magnetic sensors  115   1 - 115   x  are configured to be sensitive only to changes in magnetic field in the z-axis. Other orientations are possible so long as the magnetic skin tags  130   1 - 130   x  are magnetized in the direction in which the magnetic skin tags  130   1 - 130   x  move relative to the magnetic sensors  115   1 - 115   x  for making the facial expressions that correspond to commands. 
     A non-limiting example of the changes in magnetic field signals for different facial expressions is illustrated in  FIG.  5   , in which the solid trace represents changes in magnetic fields sensed by the magnetic sensors arranged on the nose and the dashed trace represents changes in magnetic fields sensed by the magnetic sensor on the bridge of the pair of glasses  105 . Starting from the left side of the graph, a neutral face is the baseline for measuring changes in magnetic fields, and thus does not produce a change in the magnetic fields sensed by any of the magnetic sensors  115   1 - 115   x . Moving both eyebrows up causes the magnetic sensor arranged on the bridge of the pair of glasses  105  to sense a negative change in magnetic field and moving both eyebrows down causes the magnetic sensor arranged on the bridge of the pair of glasses  105  to sense a positive change in magnetic field. Moving the nose to the right causes the magnetic sensors arranged on the lower part of the pair of glasses  105  to sense a positive change in magnetic field and moving the nose to the left causes the magnetic sensors arranged on the lower part of the pair of glasses  105  to sense a negative change in magnetic field. In the example illustrated in  FIG.  5   , the changes in magnetic fields sensed by the magnetic sensors arranged in the lower part of the pair of glasses  105  (i.e., the magnetic sensors arranged to sense nose movements) are differential signals, which improves the signal-to-noise ratio of the signal, and thus reduce false positive and false negative interpretations of facial movements as being intended to issue a command. Specifically, the voltage corresponding to the determined change in magnetic field V nose  is the difference between the voltage corresponding to the magnetic field measured for the magnetic skin tag arranged on the right-side of the face V R  and the magnetic skin tag arranged on the left side of the face V L  (i.e., V nose =V R −V L ). Thus, when the nose moves to the right, V R  becomes larger and V L  becomes smaller, and thus V nose  is positive. Likewise, when the nose moves to the left, V R  becomes smaller and V L  becomes larger, and thus V nose  is negative. It should be recognized that the differential signals can be processed in the opposite manner, i.e., V nose =V L −V R . As illustrated in  FIG.  5   , because the magnetic skin tags  130   1 - 130   x  are magnetized in the direction of the z-axis, the change in magnetic field that is sensed is due to the slight downward movement of the nose when moving the nose left or right. 
     In addition to commands being based on movement of either the glabella or the nose, a combination of movements can be employed as commands. A non-limiting example of movements (which can also be referred to as gestures) and the corresponding comments is illustrated in the following table: 
     
       
         
           
               
               
             
               
                   
               
               
                 Movement 
                 Command 
               
               
                   
               
             
            
               
                 No expression 
                 Null command (no command issued) 
               
               
                 Eyebrows up 
                 Move power-driven mobility device forward or 
               
               
                   
                 turn further device on 
               
               
                 Eyebrows down 
                 Move power-driven mobility device backward or 
               
               
                   
                 turn further device off 
               
               
                 Nose right 
                 Turn power-driven mobility device right or move 
               
               
                   
                 computer cursor right 
               
               
                 Nose left 
                 Turn power-driven mobility device left or move 
               
               
                   
                 computer cursor left 
               
               
                 Eyebrows up and nose 
                 Turn power-driven mobility device right while 
               
               
                 right 
                 still moving forward or move computer cursor 
               
               
                   
                 diagonally towards the upper right of the screen 
               
               
                 Eyebrows up and nose 
                 Turn power-driven mobility device left while 
               
               
                 left 
                 still moving forward or move computer cursor 
               
               
                   
                 diagonally towards the upper left of the screen 
               
               
                 Eyebrows down and 
                 Turn power-driven mobility device right while 
               
               
                 nose right 
                 still moving backward or move computer cursor 
               
               
                   
                 diagonally towards the lower right of the screen 
               
               
                 Eyebrows down and 
                 Turn power-driven mobility device left while 
               
               
                 nose left 
                 still moving backward or move computer cursor 
               
               
                   
                 diagonally towards the lower left of the screen 
               
               
                 Double eyebrows up 
                 No command for power-driven mobility device; 
               
               
                   
                 Select option for further device to further 
               
               
                   
                 devices that have selection options 
               
               
                 Triple eyebrows up 
                 Mode switch command between mode for 
               
               
                   
                 controlling power-driven mobility device and 
               
               
                   
                 mode for controlling further device 
               
               
                 Double eyebrows up 
                 No command for power-driven mobility device; 
               
               
                 and nose right 
                 Right-click on computer 
               
               
                 Double eyebrows up 
                 No command for power-driven mobility device; 
               
               
                 and nose left 
                 Left-click on computer 
               
               
                   
               
            
           
         
       
     
     The table above, or a similar table, can be implemented as a look-up table by the processor  210  of the power-driven mobility device  205  by including one or more columns for the voltage values provided by each of the magnetic sensors  115   1 - 115   x . The correlation between facial movements and commands in the table above is simply one example and other correlations can be employed. Further, double and triple nose movements could be employed to extend the number of available commands. 
     As discussed above, the plurality of magnetic skins tags  130   1 - 130   x  are designed to be attached to a human face, and in many cases are intended to be worn for at least a few hours, if not longer. Thus, the plurality of magnetic skins tags  130   1 - 130   x  are designed to be stretchable, flexible, comfortable, and biocompatible. In one non-limiting embodiment, the plurality of magnetic skins tags  130   1 - 130   x  are comprised of a mixture of a silicon-based elastomer matrix (e.g., material sold under the name Ecoflex by Smooth-On) with a permanent magnetic powder (e.g., NdFeB) with a 1:1 weight ratio. It was found that this weight ratio offers the best combination of high remanent magnetization and high flexibility. Specifically, this weight ratio produced a magnetic skin tag having a Yong&#39;s modulus of 129 kPa, which is more than 17 times lower compared to conventional Sylgard-based magnetic composites, which have a Young&#39;s modulus greater than 2,200 kPa. The ultra-low Young&#39;s modulus of the magnetic skins tags  130   1 - 130   x  makes the presence of the magnetic skin tags almost imperceptible to the wearer. A magnetic skin tag with the 1:1 weight ratio noted above and having dimensions of 10×2×.07 mm 3  exhibited a magnetic flux density of 177 μT at a distance of 7 mm, which provides a sufficient magnetic field for detection by the magnetic sensors with a good signal-to-noise ratio. A magnetic skin tag with the 1:1 weight ratio noted above was subject to stress testing, which demonstrated that the magnetic skin tag maintained its properties over 1000 stress cycles, each cycle involving stretching the magnetic skin tag from its normal length to 180% percent of its normal length and then relaxing the magnetic skin tag to 50% of its normal length. Biocompatibility of the magnetic skin tag with the 1:1 weight ratio noted above was demonstrated using a PrestoBlue cell viability test, where the cells maintained a high viability (i.e., &gt;90%) when cultured on top of the magnetic skin tag for three days. 
     Because the magnetic skin tags are designed to be worn for extended periods of time, the magnetic skin tags will become uncomfortable unless they are breathable, which can suppress irritations and other feelings of discomfort that might arise from wearing a magnetic skin tag. According to one non-limiting embodiment, breathability is achieved by introducing micro-holes in the magnetic skin tag. For example, after preparing the magnetic skin tag using the 1:1 weight ratio noted above, micro-holes having a diameter of, for example, 70 μm are formed using a 30 W ytterbium fiber laser with a 1.06 μm wavelength. In one embodiment, the magnetic skin tag has a hole density of up to 2,500 holes/cm 2 , which is four times the density of human sweat glands. Even with the presence of these micro-holes, it was found that a magnetic skin tag that was 0.1 mm thick and had 1,250 holes/cm 2  could withstand more than 300% elongation and exhibited a coercivity of 560 mT, which is the required external field to demagnetize the magnetic skin tags. The remanent magnetization is the magnetic field embedded in the magnetic skin tags after being magnetized along the z-axis. In one embodiment, a magnetic skin tag, without any holes, with the 1:1 weight ratio exhibited a remanent magnetization of 126 mT. 
     Testing showed that the magnetic field drops approximately 20% for every added 1,250 holes/cm 2  (or about 1% per 62 holes). Because breathability is characterized by the water vapor transmission rate (WVTR), which is a measure of the vapor permeability of a substrate, the WVTR of the magnetic skin tag with different hole densities were tested and the highest WVTR was found to be 95×10 3  g·m −2 ·day −1  (with a hole density of approximately 2,500 holes/cm 2 , which is about two orders of magnitude higher than the range of 200-500 g·m −2 ·day −1  of human skin. The WVTR testing also found that a magnetic skin tag with a hole density of 1,250 holes/cm 2  offers a high breathability of 60×10 3  g·m −2 ·day −1  while reducing the magnetic field by only 20% compared to the magnetic field without any holes. 
     Although embodiments discussed above involve using the processor of the power-driven mobility device as a gateway for sending commands between the glasses and a further device, it should be recognized that further embodiments can omit the power-driven mobility device as a gateway and allow the glasses to send commands directly to a further device. This can be achieved using radio frequency communications and/or line-of-sight communications. When only line-of-sight communications are employed, the glasses can omit the radio frequency transmitter (or transceiver) and include a line-of-sight transmitter (or transceiver), and when only radio frequency communications are employed, the glasses can use the disclosed transmitter (or transceiver) to communicate with the further device using radio frequencies. 
     As will be appreciated from the discussion above, the disclosed embodiments provide a cost-effective solution for assisting quadriplegics and others with physical disabilities for operating a power-driven mobility device and other devices that does not involve complicated, invasive and bulky equipment, and does not require a large amount of processing power. Accordingly, the disclosed embodiments provide a particularly advantageous system for controlling power-driven mobility devices and other devices. 
     The disclosed embodiments provide a system for controlling devices, including power-driven mobility devices and devices other than power-driven mobility devices, using facial movements. It should be understood that this description is not intended to limit the invention. On the contrary, the exemplary embodiments are intended to cover alternatives, modifications and equivalents, which are included in the spirit and scope of the invention as defined by the appended claims. Further, in the detailed description of the exemplary embodiments, numerous specific details are set forth in order to provide a comprehensive understanding of the claimed invention. However, one skilled in the art would understand that various embodiments may be practiced without such specific details. 
     Although the features and elements of the present exemplary embodiments are described in the embodiments in particular combinations, each feature or element can be used alone without the other features and elements of the embodiments or in various combinations with or without other features and elements disclosed herein. 
     This written description uses examples of the subject matter disclosed to enable any person skilled in the art to practice the same, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the subject matter is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims.