Patent Publication Number: US-2017365403-A1

Title: Passive alignment system and method

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The present disclosure is related and claims priority to U.S. Provisional Pat. Appl. No. 62/351,153, entitled PASSIVE ALIGNMENT SYSTEM, to Thomas Stout, filed on Jun. 16, 2016, the contents of which are hereby incorporated by reference in their entirety, for all purposes. 
    
    
     BACKGROUND 
     Field of Disclosure 
     Embodiments described herein are generally related to the field of wireless powering of electronic devices. More specifically, embodiments described herein are related to systems and methods for aligning an electronic device relative to a remote power supply for efficient wireless power transfer to the electronic device. One or more of these embodiments may be employed to transfer power to a vehicle from a base charging system. 
     Related Art 
     Current systems for aligning mobile electronic appliances with wireless recharging units make use of radiofrequency identification RFID, mechanical, optical, or visual technologies that rely on high power and/or complex circuitry. The systems are therefore costly, and also tend to interfere with the power transmission process because, e.g., of the use of resonant circuitry. Therefore, it is desirable to have an alignment system that uses low power and has little to no interference with the power transmission process. 
     SUMMARY 
     In one embodiment, an inductive alignment system includes a power source providing a forcing function and a first inductor in communication with the power source. The first inductor exhibits a first electrical property in response to the forcing function. The system also includes a second inductor in communication with the first inductor. The second inductor exhibits a second electrical property in response to the forcing function. The system includes a comparator that compares the first electrical property with the second electrical property and generates a signal based at least in part on a deviation between the first electrical property and the second electrical property. The deviation is caused at least in part by inductive coupling between a proximate object and at least one of the first inductor and the second inductor. 
     In another embodiment, a method of inductive alignment includes applying a first signal to a first inductor, the first signal provided by a power source and applying a second signal to a second inductor, the second signal provided by the power source. The method also includes measuring a first electrical property of the first inductor in response to the first signal, measuring a second electrical property of the second inductor in response to the second signal, comparing the first electrical property with the second electrical property, and generating a third signal based at least in part on a deviation between the first electrical property and the second electrical property. The deviation is caused at least in part by inductive coupling between a proximate object and at least one of the first inductor and the second inductor. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1A  illustrates an inductive alignment system including a primary coil and a first alignment coil having a mutual inductance M therebetween, according to some embodiments. 
         FIG. 1B  illustrates an inductive alignment system, according to some embodiments. 
         FIGS. 2A-C  illustrate multiple configurations of an inductive alignment system distributed over a plane, according to some embodiments. 
         FIG. 2D  illustrates an inductive alignment system where one or more alignment coils may include a three-dimensional configuration of assembly coils, according to some embodiments. 
         FIG. 3  illustrates voltage curves for multiple alignment coils in an inductive alignment system, according to some embodiments. 
         FIG. 4  illustrates an inductive alignment system including a controller to provide feedback, according to some embodiments. 
         FIG. 5  illustrates an inductive alignment system including a controller to provide feedback and a scaling block for modifying an electrical property of one of two inductors, according to some embodiments. 
         FIG. 6  illustrates an inductive alignment system including a controller to provide feedback and at least one resistor for modifying an electrical property of one of two inductors, according to some embodiments. 
         FIG. 7  illustrates an inductive alignment system including a controller to provide feedback and two inductors coupled in parallel, according to some embodiments. 
         FIG. 8  is a flow chart illustrating steps in a method of inductive alignment, according to some embodiments. 
     
    
    
     In the figures, elements and steps denoted by the same or similar reference numerals are associated with the same or similar elements and steps, unless indicated otherwise. 
     DETAILED DESCRIPTION 
     The detailed description set forth below is intended as a description of various implementations and is not intended to represent the only implementations in which the subject technology may be practiced. As those skilled in the art would realize, the described implementations may be modified in various different ways, all without departing from the scope of the present disclosure. Accordingly, the drawings and description are to be regarded as illustrative in nature and not restrictive. 
     Embodiments of the invention as disclosed herein perform alignment of a wireless charging system without the need to generate high magnetic fields, e.g., without the need to energize coils to generate those fields. Embodiments of the invention are alternatives to alignment systems that rely on RFID, mechanical, optical, or visual apparatus, particularly in the electric vehicle market. One embodiment of the invention measures the change of the leakage induction of alignment coils with a primary side coil that is usually shorted (or effectively shorted at a given frequency) and typically in a fixed location. The relative changes in alignment coil inductance give information about the coefficient of coupling between the primary side coil and the alignment coils. This allows characterizing the position of the primary side coil relative to the alignment coils. In other words, a magnetic field in one coil induces a voltage in another coil that is measured to determine proximity; e.g., the measurements provide feedback about the proximity, which includes both distance and direction between the primary side coil and the alignment coils. 
       FIG. 1A  illustrates an inductive alignment system  100 A including a primary coil  101  having a first inductance L 1  and a first alignment coil  105  having a second inductance L 2 . In general, first alignment coil  105  may be separated by a distance, D, from primary coil  101 . Further, an axis A 1  through primary coil  101  may form an angle, θ, with an axis A 2  through first alignment coil  105 . Inductances L 1  and L 2  mutually affect each other through a mutual inductance, M, according to some embodiments. M is typically a function of D and θ. Primary coil  101  may be powered by an alternating-current (AC) source  150 , generating a voltage V 1 , and a current I 1  flowing through primary coil  101 . The voltage V 1  and current I 1  generate a voltage V 2  and a current I 2  through first alignment coil  105  due to the mutual inductance factor, M. Accordingly, voltages V 1  and V 2  may satisfy the following expressions: 
         V   1   =j ω( L   1   ·I   1   +M·I   2 )  (1.1)
 
         V   2   =j ω( M·I   1   +L   2   ·I   2 )  (1.2)
 
     Where ω is the frequency of AC source  150 . System  100 A includes a capacitor  155  that introduces a resonant behavior in the inductive coupling of primary coil  101  and first alignment coil  105 . Accordingly, for high ω relative to 1/C (where the impedance is 1/ωC), primary coil  101  is substantially shorted down to ground voltage, V g  (e.g., zero) 
     Assuming V g =0, under high frequency conditions, then, V 1  is shorted down to zero and the following is true: 
     
       
         
           
             
               
                 
                   
                     I 
                     1 
                   
                   = 
                   
                     
                       
                         - 
                         M 
                       
                       · 
                       
                         I 
                         2 
                       
                     
                     
                       L 
                       1 
                     
                   
                 
               
               
                 
                   ( 
                   2 
                   ) 
                 
               
             
           
         
       
     
     And using Eq. (2) into Eq. 1.2: 
     
       
         
           
             
               
                 
                   
                     V 
                     2 
                   
                   = 
                   
                     
                       j 
                        
                       
                           
                       
                        
                       
                         ω 
                          
                         
                           ( 
                           
                             
                               
                                 L 
                                 2 
                               
                               · 
                               
                                 I 
                                 2 
                               
                             
                             - 
                             
                               
                                 
                                   M 
                                   2 
                                 
                                  
                                 
                                   I 
                                   2 
                                 
                               
                               
                                 L 
                                 1 
                               
                             
                           
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                     = 
                     
                       
                         
                           I 
                           2 
                         
                         · 
                         j 
                       
                        
                       
                           
                       
                        
                       
                         ω 
                          
                         
                           ( 
                           
                             
                               L 
                               2 
                             
                             - 
                             
                               
                                 M 
                                 2 
                               
                               
                                 L 
                                 1 
                               
                             
                           
                           ) 
                         
                       
                     
                   
                 
               
               
                 
                   ( 
                   3 
                   ) 
                 
               
             
           
         
       
     
     And, by analogy with Eqs. 1.1 and 1.2, an effective inductance L s  may be defined as: 
     
       
         
           
             
               
                 
                   
                     L 
                     s 
                   
                   = 
                   
                     
                       L 
                       2 
                     
                     - 
                     
                       
                         M 
                         2 
                       
                       
                         L 
                         1 
                       
                     
                   
                 
               
               
                 
                   ( 
                   4 
                   ) 
                 
               
             
             
               
                 Wherein 
               
               
                 
                     
                 
               
             
             
               
                 
                   
                     V 
                     2 
                   
                   = 
                   
                     
                       
                         I 
                         2 
                       
                       · 
                       j 
                     
                      
                     
                         
                     
                      
                     
                       ω 
                       · 
                       
                         L 
                         s 
                       
                     
                   
                 
               
               
                 
                   ( 
                   5 
                   ) 
                 
               
             
           
         
       
     
     Accordingly, L s  may be interpreted as the inductance measured across L 2  when primary coil  101  is shorted (e.g., at high frequencies, ω). From Eq. 4, the value of the mutual inductance, M, may be found as 
         M =√{square root over ( L   1 ·( L   2   −L   s ))}  (6)
 
     A unit-less coupling coefficient, k, may be further defined as 
     
       
         
           
             
               
                 
                   k 
                   = 
                   
                     
                       M 
                       
                         
                           
                             L 
                             1 
                           
                           · 
                           
                             L 
                             2 
                           
                         
                       
                     
                     = 
                     
                       
                         ( 
                         
                           1 
                           - 
                           
                             
                               L 
                               s 
                             
                             
                               L 
                               2 
                             
                           
                         
                         ) 
                       
                     
                   
                 
               
               
                 
                   ( 
                   6 
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     Measurement of L s  when primary coil  101  is shorted, together with prior knowledge of L 2 , gives a measure of coupling coefficient, k. The coupling coefficient, k, is a unit-less value between 0 and 1, which is typically proportional to D and inversely proportional to θ. The measured inductance L 2  will change to L s  when primary coil  101  is shorted, which occurs under conditions where the frequency causes capacitor  155  to behave as an AC short. 
     System  100 A depicts a configuration where source  150  would typically provide power to a remote electronic device, e.g., act as a remote power supply to charge an electric vehicle. However, during alignment, source  150  is usually disabled and a power source  102  is applied as shown in  FIG. 1B . 
     The power source  102  provides a forcing function to a first inductor  105 A. First inductor  105 A exhibits a first electrical property in response to the forcing function (e.g., a measured value at probe point  130 A). The power source  102  provides the forcing function to a second inductor  105 B by virtue of the latter&#39;s connection to the first inductor  105 A. The second inductor  105 B exhibits a second electrical property in response to the forcing function (e.g., a measured value at probe point  130 B). In some embodiments, first inductor  105 A is coupled in series with second inductor  105 B. In other embodiments the inductors  105 A,  105 B are coupled in parallel. 
     The forcing function can be a current source or a voltage source. In the case of the former, current applied to the first inductor  105 A and second inductor  105 B (hereinafter, collectively referred to as “inductors  105 ”) gives rise to voltages measured at probe points  130 A,  130 B. If the forcing function is a voltage source, then a current would be measured at probe points  130 A,  130 B. In either case, the forcing function typically operates at a frequency, co, sufficient to cause a short across the primary coil  101 , potentially leaving parasitic resistance  140 . The frequency is generally higher than the resonant frequency of the circuit containing the primary coil  101 , e.g., 100 kHz versus 20 kHz. 
     Comparator  120  generates a signal based at least in part on a deviation between the first electrical property and the second electrical property. The deviation is caused at least in part by inductive coupling (e.g., through coupling coefficient, k, cf. Eq. 6) between a proximate object  110  and first inductor  105 A and/or second inductor  105 B. A first coupling coefficient k 1  (cf. Eq. 6) may result between primary coil  101  and first inductor  105 A. A second coupling coefficient, k 2 , may result between primary coil  101  and the second inductor  105 B. 
     The deviation provides an indication of a difference between the two coupling coefficients k 1  and k 2 . Further, the difference between k 1  and k 2  may be associated with a location of proximate object  110  relative to first alignment coil  105 A and second alignment coil  105 B. In some embodiments, first inductor  105 A and second inductor  105 B are identical coils. The first inductor  105 A may be located in a predetermined location relative to the second inductor  105 B, e.g., positioned at different points along an axis and/or spaced apart by a known distance. Thus, the difference between coupling coefficients k 1  and k 2  indicates how well the center of primary coil  101  is aligned with the axis. First inductor  105 A and second inductor  105 B can be placed in any arrangement where the desired axes (e.g., at least one of an X-axis, Y-axis, or Z-axis) are covered, to provide alignment guidance. 
     In some embodiments, the first inductor  105 A and/or second inductor  105 B is moving relative to proximate object  110 . This might occur, for example, when one or both of the inductors  105 A,  105 B are included in a vehicle that is moving and will be used to align the vehicle with a charging system, e.g., the proximate object  110 . 
     In some embodiments, at least one, or all, of power source  102 , inductors  105 , and comparator  120  are part of a mobile electronic appliance (e.g., a vehicle, a cell phone, a smartphone, a laptop, a tablet, or any other portable computing device). Further, in some embodiments proximate object  110  includes a stationary wireless power provider. Accordingly, inductive alignment system  100 B may be configured so that the mobile electronic appliance detects proximate object  110 , and determines an optimal alignment between the mobile electronic appliance with the primary coil of proximate object  110  so that a power transfer may occur between proximate object  110  and a battery in the mobile electronic appliance. 
     Some embodiments measure the inductance of inductors  105  as they approach or move relative to the proximate object  110 , when primary coil  101  is shorted as described above. Alternatively, a second, smaller coil, coincident with the primary coil  101 , can be used for alignment purposes instead of the primary coil  101 , which is used for power transfer. This second coil, typically constructed using smaller wire compared to that used in primary coil  101 , would be short circuited when alignment was being performed, and open circuited during power transfer. Coincidence between the primary coil  101  and the second coil can be achieved by, e.g., ensuring that both coils have the same center point. 
     Once a location configuration between inductors  105  and proximate object  110  is determined (e.g., an optimal alignment and proximity between inductors  105  and a primary coil  101 ), the short in the primary coil  101  may be removed to prevent fusing open the circuit in proximate object  110  during power transfer. Thereafter, proximate object  110  may transmit power wirelessly to the mobile electronic appliance. In other words, primary coil  101  could be shorted during alignment and driven normally during power transfer. 
     In some embodiments, primary coil  101  may be coupled in series with a resonant capacitor (not shown) and a power transfer inverter (e.g., AC source  150  in  FIG. 1A ). When the inverter is disabled (e.g., shorted), the series capacitor acts as a high frequency short. An H-bridge configuration for the power transfer inverter this can be accomplished by closing both low side switches or both high side switches in the H-bridge. This requires minimal controls using switches that are typically already present in proximate object  110 . 
       FIGS. 2A-C  illustrate multiple configurations  200 A,  200 B, and  200 C, respectively (hereinafter, collectively referred to as “configurations  200 ”), of an inductive alignment system distributed over a plane (defined, for illustrative purposes only, as an X-Y plane), according to some embodiments. Configuration  200 A includes inductors  205 A,  205 B, and  205 C forming a triangle configuration between axes X and Y. Configuration  200 B is similar to configuration  200 A, with the addition of inductor  205 D to form a square arrangement in the XY plane. Inductors  205 A,  205 B,  205 C, and  205 D will be collectively referred to, hereinafter, as inductors  205 . 
     Configuration  200 C is similar to configuration  200 B, with the addition of a power transfer coil  210 . Power transfer coil  210  may be configured to provide wireless power to a mobile electronic appliance that includes inductors  205 , when an alignment and a proximity measurement determines an optimal location configuration between the mobile electronic appliance and power transfer coil  210 . Accordingly, power transfer coil  210  may have axes X′ and Y′ as magnetic symmetry axis. Note that coordinate axes X′Y′ may not only be skewed relative to axes XY, but also de-centered, thus creating asymmetric mutual inductances between power transfer coil  210  and each one of inductors  205 . 
     In some embodiments, the relative change in inductance between inductors  205  is measured by coupling a pair of inductors along one axis in series (e.g., inductors  205 A and  205 B along the Y-axis in configuration  200 A), and drive a fixed AC current or voltage into the series combination. The voltage across each inductor  205 A or  205 D will be equal when the Y-axis between inductors  205 A and  205 D is perfectly aligned with the Y′-axis of power transfer coil  210 . The voltage across inductors  205 A and  205 D may be different when the Y-axis is misaligned relative to the Y′ axis of power transfer coil  210 . For example, typically the inductor that is closer to the center of power transfer coil  210  will have a smaller effective inductance, and therefore will have a smaller voltage across it. A comparison between the two voltages (e.g., furnished by comparator  120 , cf.  FIG. 1B ) can give directional information along axis Y. 
     Without limitation, configurations  200  may be extended to a three-dimensional alignment configuration. For example, in some embodiments, at least one of inductors  205 A,  205 B,  205 C, and  205 D includes at least three assembly coils. Each assembly coil has a longitudinal axis and is oriented orthogonally to a plane defined by the longitudinal axes of two other assembly coils (e.g., in an XYZ three-dimensional configuration). One such embodiment  210  is depicted in  FIG. 2D , where three assembly coils C x , C y , and C z  are disposed orthogonally. Voltages appearing across these coils are denoted V x , V y , and V z , respectively. 
     Some embodiments may include a 3-axis alignment sensor. In such configuration, three inductors may be oriented in each of the 3 axes (e.g., XYZ) with the same (or close to) origin, all with the same inductance and all connected in series. This group of three inductors would then represent a single “alignment inductor” representing a more uniform measurement of the value of coupling coefficient, k. In some embodiments, the inductor geometries for each axis may be different from each other. 
       FIG. 3  illustrates chart  300  with voltage curves  305 - 1 ,  305 - 2 ,  305 - 3 ,  305 - 4 ,  305 - 5 , and  305 - 6  (hereinafter, collectively referred to as “curves  305 ”), for multiple alignment coils in an inductive alignment system such as any of the configurations  200  (cf.  FIGS. 2A-C ), according to some embodiments. Any one of configurations  200  may be simulated in SPICE with the values of k for the two coils sweeping in opposite directions. In addition, curves  305  in chart  300  include a third, orthogonal axis (e.g., axis Z). Similar to configurations  200 , for chart  300  a pair of inductors is symmetrically moved along each of three orthogonal axes, in opposite directions. For example, curve  305 - 1  corresponds to the voltage over time for inductor  205 A moving along the +Y direction and curve  305 - 2  corresponds to the voltage over time for inductor  205 D moving symmetrically, in the −Y direction. Likewise, curve  305 - 3  corresponds to the voltage over time for inductor  205 C moving along the +X direction and curve  305 - 4  corresponds to the voltage over time for inductor  205 B moving symmetrically, in the −X direction. Further, curve  305 - 5  corresponds to the voltage over time for an inductor moving along the +Z direction and curve  305 - 6  corresponds to the voltage over time for an identical inductor moving symmetrically, in the −Z direction. At any point in time, the difference in voltages between each of the curves  305 - 1  and  3052 ,  305 - 3  and  305 - 4 , and  305 - 5  and  305 - 6  may indicate a distance of the respective inductor relative to the primary coil. Moreover, the difference between the specific values of curves  305  associated with different axes may indicate a relative orientation of the primary coil relative to the XYZ system chosen for curves  305 . 
       FIG. 4  illustrates an inductive alignment system  400  including a controller  450  to provide feedback through a feedback block  454  regarding the location of a first inductor  405 A and/or a second inductor  405 B (hereinafter, collectively referred to as “inductors  405 ”) relative to a proximate object including a primary coil (e.g., primary coil  101 , not illustrated in the figure), according to some embodiments. Controller  450  may include a processor circuit that determines the location of the proximate object, based at least in part on the signal that comparator  452  generates. 
     There are several ways that the comparison could be made between inductors  405 . For example: controller  450  may use analog inputs from amplifying stages  440 A and  440 B. An amplifier  452  provides an amplified signal proportional to the difference between signals provided by amplifiers  440 A and  440 B to feedback block  454 . In some embodiments, the comparison could be made outside controller  450 . The comparison can be made directly between the voltages of inductors  405 A and  405 B at probe points  430 A and  430 B, respectively. The comparison could also be made from a center probe point  430 C. The voltage at point  430 C may move higher/lower but the voltage between two resistors in a similar configuration (see  FIG. 6 ) will remain fixed as the alignment with the proximate object changes. In some configurations the high frequency AC source  401  could be either a voltage or current source. 
     In some embodiments, the location of the proximate object includes distance and direction information. In some embodiments, processor  450  computes a difference between (i) a first coupling coefficient that characterizes the inductive coupling between the proximate object and first inductor  405 A, and (ii) a second coupling coefficient that characterizes the inductive coupling between the proximate object and second inductor  405 B. In some embodiments, computation of the difference between the two coupling coefficients does not require computation of either or both coupling coefficients. 
       FIG. 5  illustrates an inductive alignment system  500  including a controller  550  to provide feedback through feedback block  454  regarding the location of first inductor  405 A and/or second inductor  405 B relative to a proximate object including a primary coil (e.g., primary coil  101 , not illustrated in the figure). Inductive alignment system  500  also includes a scaling block  552  for modifying an electrical property of inductor  405 A, according to some embodiments. Scaling block  552  may include an amplifier, or a current to voltage converter, or any other combination of electronic devices configured to increase or decrease the value of the electrical property of inductor  405 A to a value comparable with that of inductor  405 B (e.g., within the dynamic range of amplifier  452 ). 
       FIG. 6  illustrates an inductive alignment system  600  including a controller  450  to provide feedback through feedback block  454  regarding the location of first inductor  405 A and/or second inductor  405 B relative to a proximate object including a primary coil (e.g., primary coil  101 , not illustrated in the figure). Inductive alignment system  600  includes a first resistor  640 A, and a second resistor  640 B (hereinafter, collectively referred to as “resistors  640 ”), for modifying an electrical property of inductor  405 A and second inductor  405 B, according to some embodiments. Further, inductive alignment system  650  includes a probe point  630  in the middle of resistors  640 , which are coupled in series with each other, and in parallel with respect to inductors  405 . Accordingly, amplifier  452  is fed a differential voltage between probe point  630  and probe point  430 C. Therefore, movement of inductive alignment system  600  relative to the proximate object will change a voltage in point  430 C but not in probe point  630 . 
       FIG. 7  illustrates an inductive alignment system  700  including a controller  450  to provide feedback through feedback block  454  regarding the location of a first inductor  705 A and/or a second inductor  705 B relative to a proximate object including a primary coil (e.g., primary coil  101 , not illustrated in the figure). Inductive alignment system  700  includes a first inductor  705 A and a second inductor  705 B (hereinafter, collectively referred to as “inductors  705 ”) coupled in parallel, according to some embodiments. 
     In some embodiments, the feedback described above is used to provide information to the user of the appliance (e.g., the vehicle operator) regarding the position of the appliance (e.g., vehicle) relative to the charging station. This allows the user (e.g., operator) to move the appliance (e.g., vehicle) into proper alignment with the charging station while monitoring the feedback information. In some embodiments, the feedback information may be provided to the user (e.g., operator) as described in U.S. patent application Ser. No. 15/092,608, the contents of which are incorporated by reference herein in their entirety, for all purposes. 
       FIG. 8  is a flow chart illustrating steps in a method  800  of inductive alignment, according to some embodiments. Methods consistent with method  800  may include at least one, but not all of the steps in method  800 . At least some of the steps in method  800  may be performed by a processor circuit in a computer (e.g., processor  450 ), wherein the processor circuit is configured to execute instructions and commands stored in a memory. Further, methods consistent with the present disclosure may include at least some of the steps in method  800  performed in a different sequence. For example, in some embodiments a method may include at least some of the steps in method  800  performed in parallel, simultaneously, almost simultaneously, or overlapping in time. 
     Step  802  includes applying a first signal to a first inductor, the first signal provided by a power source. 
     Step  804  includes applying a second signal to a second inductor, the second signal provided by the power source. 
     In some embodiments, the first signal may be the same as the second signal. 
     Step  806  includes measuring a first electrical property of the first inductor in response to the first signal. 
     Step  808  includes measuring a second electrical property of the second inductor in response to the second signal. 
     Step  810  includes comparing the first electrical property with the second electrical property. 
     Step  812  includes generating a third signal based at least in part on a deviation between the first electrical property and the second electrical property, wherein the deviation is caused at least in part by inductive coupling between a proximate object and at least one of the first inductor and the second inductor. In some embodiments, step  812  further includes determining a location of the proximate object relative to at least one of the location of the first inductor and the location of the second inductor, based at least in part on the third signal. In some embodiments, the location of the proximate object includes distance and direction information. 
     To the extent that the term “include,” “have,” or the like is used in the description or the claims, such term is intended to be inclusive in a manner similar to the term “comprise” as “comprise” is interpreted when employed as a transitional word in a claim. 
     The word “exemplary” is used herein to mean “serving as an example, instance, or illustration.” Any embodiment described herein as “exemplary” is not necessarily to be construed as preferred or advantageous over other embodiments. Phrases such as an aspect, the aspect, another aspect, some aspects, one or more aspects, an implementation, the implementation, another implementation, some implementations, one or more implementations, an embodiment, the embodiment, another embodiment, some embodiments, one or more embodiments, a configuration, the configuration, another configuration, some configurations, one or more configurations, the subject technology, the disclosure, the present disclosure, other variations thereof and alike are for convenience and do not imply that a disclosure relating to such phrase(s) is essential to the subject technology or that such disclosure applies to all configurations of the subject technology. A disclosure relating to such phrase(s) may apply to all configurations, or one or more configurations. A disclosure relating to such phrase(s) may provide one or more examples. A phrase such as an aspect or some aspects may refer to one or more aspects and vice versa, and this applies similarly to other foregoing phrases. 
     A reference to an element in the singular is not intended to mean “one and only one” unless specifically stated, but rather “one or more.” The term “some” refers to one or more. Underlined and/or italicized headings and subheadings are used for convenience only, do not limit the subject technology, and are not referred to in connection with the interpretation of the description of the subject technology. Relational terms such as first and second and the like may be used to distinguish one entity or action from another without necessarily requiring or implying any actual such relationship or order between such entities or actions. All structural and functional equivalents to the elements of the various configurations described throughout this disclosure that are known or later come to be known to those of ordinary skill in the art are expressly incorporated herein by reference and intended to be encompassed by the subject technology. Moreover, nothing disclosed herein is intended to be dedicated to the public regardless of whether such disclosure is explicitly recited in the above description. No claim element is to be construed under the provisions of 35 U.S.C. §112(f), unless the element is expressly recited using the phrase “means for” or, in the case of a method claim, the element is recited using the phrase “step for.” 
     While this specification contains many specifics, these should not be construed as limitations on the scope of what may be claimed, but rather as descriptions of particular implementations of the subject matter. Certain features that are described in this specification in the context of separate embodiments can also be implemented in combination in a single embodiment. Conversely, various features that are described in the context of a single embodiment can also be implemented in multiple embodiments separately or in any suitable subcombination. Moreover, although features may be described above as acting in certain combinations and even initially claimed as such, one or more features from a claimed combination can in some cases be excised from the combination, and the claimed combination may be directed to a subcombination or variation of a subcombination. 
     The subject matter of this specification has been described in terms of particular aspects, but other aspects can be implemented and are within the scope of the following claims. For example, while operations are depicted in the drawings in a particular order, this should not be understood as requiring that such operations be performed in the particular order shown or in sequential order, or that all illustrated operations be performed, to achieve desirable results. The actions recited in the claims can be performed in a different order and still achieve desirable results. As one example, the processes depicted in the accompanying figures do not necessarily require the particular order shown, or sequential order, to achieve desirable results. In certain circumstances, multitasking and parallel processing may be advantageous. Moreover, the separation of various system components in the aspects described above should not be understood as requiring such separation in all aspects, and it should be understood that the described program components and systems can generally be integrated together in a single software product or packaged into multiple software products. 
     The title, background, brief description of the drawings, abstract, and drawings are hereby incorporated into the disclosure and are provided as illustrative examples of the disclosure, not as restrictive descriptions. It is submitted with the understanding that they will not be used to limit the scope or meaning of the claims. In addition, in the detailed description, it can be seen that the description provides illustrative examples and the various features are grouped together in various implementations for the purpose of streamlining the disclosure. The method of disclosure is not to be interpreted as reflecting an intention that the claimed subject matter requires more features than are expressly recited in each claim. Rather, as the claims reflect, inventive subject matter lies in less than all features of a single disclosed configuration or operation. The claims are hereby incorporated into the detailed description, with each claim standing on its own as a separately claimed subject matter. 
     The claims are not intended to be limited to the aspects described herein, but are to be accorded the full scope consistent with the language claims and to encompass all legal equivalents. Notwithstanding, none of the claims are intended to embrace subject matter that fails to satisfy the requirements of the applicable patent law, nor should they be interpreted in such a way.