Patent Publication Number: US-2017361867-A1

Title: Steering input sensor for a steer-by-wire assembly

Description:
TECHNICAL FIELD 
     The present disclosure relates to a steering input sensor for a steer-by-wire assembly. 
     BACKGROUND 
     Conventional vehicle steering systems utilize a mechanical steering linkage between a vehicle steering wheel and the road wheels. Thus, when a driver actuates the steering wheel, the mechanical linkage moves in a corresponding manner and the wheels are turned. Since steer-by-wire systems utilize different components than mechanical systems, there is a need to, among other things, provide a mechanism to accept steering input, and based on that steering input, determine how much and with what force to turn the wheels. 
     SUMMARY 
     In at least some implementations, a steer-by-wire assembly for a steering system in a vehicle includes a first shaft, a second shaft, a first gear, a second gear, a first sensing element, and a second sensing element. The first shaft is rotatable in response to a steering input, and the second shaft is adapted to rotate in response to rotation of the first shaft. The first gear may rotate in response to rotation of the first shaft, and the second gear may rotate in response to rotation of the second shaft, wherein each of the first and second gears carry a sensed element. The first sensing element may be adapted to sense the element carried by the first gear and provide an output associated with an angular position of the first gear, and the second sensing element may be adapted to sense the element carried by the second gear and provide an output associated with an angular position of the second gear. And when the second shaft rotates relative to the first shaft, the outputs provide position and torque data associated with the steering input. 
     In at least some implementations, a method of determining steering input position data and torque data for a vehicle steering system is provided. The method includes: receiving a first electrical output from a first sensing element that detects rotation of a first shaft using a first gear ratio, wherein the first shaft is coupled to a second shaft via a torsion bar; receiving a second electrical output from a second sensing element that detects rotation of the second shaft using a second gear ratio that is different than the first gear ratio; and using the first and second gear ratios, determining steering input position data and steering input torque data based on the first and second electrical outputs. 
     Other embodiments can be derived from combinations of the above and those from the embodiments shown in the drawings and the descriptions that follow. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The following detailed description of preferred implementations and best mode will be set forth with regard to the accompanying drawings, in which: 
         FIG. 1A  illustrates a steer-by-wire system that includes a steer-by-wire assembly, shown in perspective, and a schematic diagram of the remainder of the system; 
         FIG. 1B  is another perspective view of the steer-by-wire assembly; 
         FIG. 2  is a partial sectional view of the steer-by-wire assembly shown in  FIGS. 1A-1B ; 
         FIG. 3  is an exploded view of a shaft and shaft components of the steer-by-wire assembly; 
         FIG. 4  is a partial sectional view of the assembled shaft and shaft components; 
         FIGS. 5A-5B  are perspective views of end portions of a first shaft component and a second shaft component, respectively; 
         FIG. 6  is a perspective view of a steering input sensor, wherein the shaft and housing are shown in section; 
         FIG. 7  is an enlarged view of the steering input sensor shown in  FIG. 2 ; 
         FIG. 8  is a partial perspective view of the steering input sensor without the housing—illustrating a secondary gear partially in section; 
         FIG. 9  is an exploded view of the steering input sensor, wherein the shaft and shaft components are hidden; 
         FIG. 10  is an exploded perspective view of part of a motorized feedback assembly; 
         FIG. 11  is a sectional perspective view of part of the feedback assembly; 
         FIG. 12  is a sectional view of part of the steer-by-wire assembly, wherein a portion of the assembly is cut away to illustrate the motorized feedback system; 
         FIGS. 13-15  are graphical depictions of Hall sensor data associated with an exemplary angular steering input range; and 
         FIG. 16  is a flow diagram illustrating a method of determining steering position data and steering torque data. 
     
    
    
     DETAILED DESCRIPTION 
     Referring in more detail to the drawings,  FIG. 1A  illustrates one embodiment of a vehicle steer-by-wire system  10  that includes a steer-by-wire assembly  12  electrically coupled to a vehicle steering mechanism  14  and a vehicle ignition system  18 . The ignition system  18  may include any suitable components to control the delivery of electrical power  16  to the steer-by-wire assembly  12 . And the steering mechanism  14  may include a controller  20 , an electric motor  22 , and a gearing system  24  used to actuate or turn the wheels  26  of a vehicle. For example, the controller  20  may receive steering control signals from the steer-by-wire assembly  12 , control the electric motor  22  using those control signals, and the electric motor  22  then may actuate the gear system  24  to turn the wheels  26 . For example, controlling the electric motor  22  to operate in a first direction (e.g., clockwise) may cause the gear assembly  24  to drive the wheels  26  rightward, while controlling the electric motor  22  to operate in an opposing direction (e.g., counter-clockwise) may cause the gear assembly  24  to drive the wheels  26  leftward. System  10  shown in  FIG. 1A  is merely illustrative, and other implementations are possible. 
     In at least one embodiment, the steer-by-wire assembly  12  includes a two-piece shaft or shaft assembly  30 , a position and torque sensing unit or steering input sensor  32 , a motorized feedback assembly  34 , and a clutch assembly  36  (see also  FIGS. 1B and 2 ). The steering input sensor  32  may be adapted to provide electrical output values associated with mechanical steering input, and, using an electronic control unit (ECU)  28 , also may correlate the output values to position and torque steering data. Thereafter, ECU  28  may command or otherwise send the position and torque steering data to the steering mechanism  14  which may control the vehicle wheels  26 . While sensor  32  receives mechanical steering input, the feedback assembly  34  may provide so-called ‘road-feel’—e.g., a rotational assistance/resistance profile experienced by the driver which typically is associated with turning a steering wheel having a mechanical linkage between the steering wheel and wheels (e.g., in a non-steer-by-wire system). The clutch assembly  36  can be adapted to provide, among other things, end stops or rotational limits for the shaft  30  and/or steering wheel  38 . In at least one embodiment, the shaft  30  at least partially passes through assemblies  32 ,  34 ,  36  and/or components thereof, as will be discussed in greater detail below. 
     The ECU  38  may include a processor or processing unit  37  and memory  39  storing instructions which are executable by the processor  37  to carry out at least a portion of the method described herein. The processor  37  can be any type of device capable of processing electronic and/or digitally-stored instructions and may include microprocessors, microcontrollers, controllers, application specific integrated circuits (ASICs), and the like. Processor  37  may be a dedicated processor used only for ECU  38 , or it can be shared with other systems. 
     The memory  39  may be coupled to processor  37  and may include any non-transitory computer usable or readable medium, which includes one or more storage devices or articles. Exemplary non-transitory computer usable storage devices include conventional computer system RAM (random access memory), ROM (read only memory), EPROM (erasable, programmable ROM), EEPROM (electrically erasable, programmable ROM), and the like. In at least one embodiment, memory  39  stores digital instructions executable by processor  37 . For example, processor  37  may be specially adapted to determine both shaft position and torque based on two sensor measurements, as will be described more below. 
     It should be appreciated that while the ECU  38  is shown mechanically spaced (e.g., remotely located) from the steering input sensor  32  and the steering mechanism  14 , this is not required. For example, in some embodiments, the ECU  28  may be mounted on or at least partially within the steer-by-wire assembly  12 . Regardless of the physical location of the ECU  28 , the ECU may be coupled electrically to both the steering input sensor  32  and the steering mechanism  14  (e.g., the controller  20  and/or the motor  22 ). And in some embodiments, the ECU  28  may be used in lieu of controller  20  and/or be located in steering mechanism  14 . 
       FIGS. 3, 4, and 5A-5B  illustrate the two-piece shaft assembly  30  in greater detail. For example, the shaft assembly  30  includes a first or upper shaft  40 , a second or lower shaft  42  coupled to the upper shaft  40 , and a torsion assembly  44  coupled to both the upper and lower shafts  40 ,  42 . FIGS.  3  and  4  illustrate the shaft assembly  30  having a number of shaft components coaxially arranged on an axis of rotation S, as will be described below. 
     The upper shaft  40  includes steering wheel coupling features  50  at a first end  52 , gear retaining features  54  on an outer surface  56  thereof, and coupling features  58  at or near a second end  60  for coupling the upper and lower shafts  40 ,  42  together. The steering wheel coupling features  50  may be any suitable element(s) adapted to retain the steering wheel  38  (shown in  FIG. 1A ); the illustrated features are merely examples. 
     As best shown in  FIG. 3 , gear retaining features  54  include any suitable features adapted to coaxially position and retain a gear of the input sensor  32  with respect to upper shaft  40 . Features  54  may be located between the first and second ends  52 ,  60  and may include a flange  64  that axially and radially extends with respect to shaft  40 , a number of circumferentially spaced tabs  66 , and a circumferential channel  68  around the shaft  40 . The flange  64  may have a shoulder  70  that faces the first end  52 , and the tabs  66  may extend axially and radially from the shaft  40  between the shoulder  70  and the first end  52 . And channel  68  may be adjacent to the tabs  66  and may be adapted to receive a retaining clip, as will be described later. Of course, these shaft features shown are merely examples; in other implementations, the gear retaining features  54  may differ. 
     As shown in  FIGS. 3 and 5A , the coupling features  58  shown at the second end  60  may include a second shoulder  74  of flange  64  that faces the second end  60 , a number of radially outwardly extending and circumferentially spaced keys A, and a number of circumferentially spaced keyways C which are interstitially-located with respect to keys A. The keys A and keyways C may be located between the shoulder  74  and the second end  60 . 
     As best shown in  FIGS. 4 and 7 , the upper shaft  40  also may include a cavity  76  which may be defined at least in part by a bore  78  extending from a base  80  and a counterbore  82  extending from the bore  78  to the second end  60  with an annular flange  84  between the bore  78  and counterbore  82 . A cross passage  86  ( FIGS. 3-4 ) may extend into or through the shaft  40  and may intersect the cavity  76  and the axis Sin the bore  78 . 
     Turning now to the lower shaft  42  ( FIGS. 3, 4, and 12 ), it has a first end  90  coupled to the upper shaft  40  and a second end  92  associated with and acted upon by the clutch assembly  36 . To receive part of the torsion assembly  44 , the first end  90  includes a cavity  94  that may be coaxially aligned with the cavity  76  in the upper shaft  40 , and oppositely facing so that, when the upper and lower shafts  40 ,  42  are coupled together, the cavities  76 ,  94  are aligned and define an enclosure for the torsion assembly  44 . In more detail, the cavity  94  in the lower shaft  42  extends from the first end  90  to a base  98  (see  FIGS. 4 and 12 ), and may be defined at least in part by a bore  100  extending from the base  98  and a counterbore  102  that extends from the bore  100  to the first end  90 —having an annular flange  104  between the bore  100  and counterbore  102 . A cross passage  106  may intersect the cavity  94  and may extend into or through the shaft  42  in the area of the bore  100 . To facilitate coupling the upper and lower shafts  40 ,  42  together, the cavity  94  in the lower shaft  42  may be sized and configured to receive the second end  60  of the upper shaft  40 , as set forth in more detail below. 
     In the example shown in  FIG. 5B , the first end  90  of the lower shaft  42  includes coupling features  107  which correspond to features  58 . In the illustration, features  107  include radially inwardly extending keys B and interstitially-located keyways D adapted to mate with keys A and keyways C of the upper shaft  40  to rotationally couple the shafts  40 ,  42  together. The keyways C, D may be circumferentially wider than the keys A, B to permit limited rotation between the shafts  40 ,  42  (e.g., 2 to 3 degrees) before keys A, B of each shaft  40 ,  42  become engaged preventing further relative rotation between the shafts  40 ,  42  in that direction. Of course, other arrangements may be provided to couple the shafts  40 ,  42  and permit at least some relative rotation between them. 
     As shown in  FIG. 3 , the lower shaft  42  may have two sets of gear retaining features  108 ,  110  two retain two different gears between the first and second ends  90 ,  92  thereof. With respect to features  108 , they may be located proximate to the first end  90  of the shaft  42 , and features  108  may include a flange  112  that extends radially outwardly with respect to shaft  42  and faces end  90 , a number of circumferentially spaced tabs  114  that extend axially and radially outwardly with respect to the shaft  42  between the flange  112  and the first end  90 , and a circumferential channel  116  around the shaft  42  adjacent the tabs  114  (e.g., adapted to receive a retaining clip). Of course, the gear retaining features  108  shown are merely examples; in other implementations, these features may be different. 
     With respect to gear retaining features  110 , they may be adapted to coaxially position and retain a gear of the feedback assembly  34  with respect to the lower shaft  42 , as will be explained more below. Features  110  may be located between the gear retaining features  108  and the second end  92  and may include a flange  122  that extends axially and radially outwardly with respect to the shaft  42 , a number of circumferentially spaced and axially extending grooves  124  in the shaft  42 , and a circumferential channel  126  around the shaft  42 . The flange  122  may have a shoulder  128  that faces the second end  92 , and the grooves  124  may extend from the shoulder  128  toward the second end  92 . Further, the channel  126  may be spaced from the shoulder  128 , may intersect the grooves  124 , and may be adapted to receive a gear retaining clip. Of course, the features  110  shown are merely examples; in other implementations, these features  110  may differ as well. 
     The lower shaft  42  may have other features that are adapted to couple or interact with other steer-by-wire components. For example, the shaft  42  may have axially extending splines between the gear retaining features  110  and the second end  92 . However, this is merely one example; and other features may be present as well. 
     Turning now to the torsion assembly  44  carried within the cavities  76 ,  94  of the upper and lower shafts  40 ,  42  ( FIGS. 3-4, 7, and 12 ), the assembly  44  may include a torsion member or bar  130 , a sleeve  132  sized to receive the torsion bar  130 , and one or more annular or ring bearings  134  sized to receive the sleeve  132 . In at least one embodiment, the torsion bar  130  has a cylindrical end region  138  coupled to another cylindrical end region  140  with a reduced diameter central region  142  therebetween. Each of the end regions  138 ,  140  may have a passage  142 ,  144  therethrough so that when the assembly  44  is located within the cavities  76 ,  94  of the upper and lower shafts  40 ,  42 , the passages  142 ,  144  may be aligned with the respective passages  86 ,  106  of the shafts so that fasteners  146 ,  148  may pin each end region  138 ,  140  to each respective shaft  40 ,  42 . In this manner, the torsion bar  130  can be fixed at its ends  138 ,  140  to shafts  40 ,  42 , respectively, and as will be explained more below, may resist relative rotation between the shafts, angularly twist under sufficient load, and facilitate measurement of a steering input torque. 
     The sleeve  132  of the torsion assembly  44  may be tubular and sized to be received over the torsion bar end regions  138 ,  140  and within the cavities  76 ,  94 . In one embodiment, an axial length of the sleeve  132  may be less than an axial length of the torsion bar  130  so that, when the bar  130  is located within the sleeve  132 , the passages  142 ,  144  of the torsion bar  130  are located without the sleeve  132 . In the implementation shown, the sleeve  132  is received within the counterbore  82 ,  102  of each cavity  76 ,  94 . And in at least one embodiment, the sleeve is press-fit within at least one of the counterbores  82 ,  102 , as will be explained more below. The sleeve  132  may promote coaxial alignment between the upper and lower shafts  40 ,  42  and, in some instances, may minimize additional slop or play which might otherwise exist between the keys A, B and keyways C, D (e.g., particularly if shafts  40 ,  42  were to become axially misaligned). 
     Bearings  134  may be any suitable bearing assemblies sized to fit within the counterbore  102  of the lower shaft  42 . For example, in the illustrated embodiment, the bearings  134  are needle roller bearings; however, this is merely an example. 
     To measure steering input angle and torque, at least some components of steering input sensor  32  (components of which are shown in  FIGS. 3-4 and 6-9 ) are mounted on or associated with the upper and lower shafts  40 ,  42 . For example, sensor  32  includes one or more gears associated with upper shaft  40 , one or more gears associated with lower shaft  42 , and sensors responsive to rotation of the upper and lower shafts  40 ,  42 . In at least one embodiment, sensor  32  includes a housing  160  having a cover  162 , a circuit card  164 , a driving or primary gear  170  carried by the upper shaft  40 , a driving or primary gear  172  carried by the lower shaft  42 , and two driven or secondary gear assemblies  174 ,  176  carried by the housing  160 . As will be explained more below, a gear  180  of the secondary assembly  174  can be used to obtain a steering input measurement while engaged with primary gear  170 , and a gear  182  of the other secondary assembly  176  can be used to obtain another steering input measurement while engaged with primary gear  172 . 
     The housing  160  may include a plurality of walls  190  and a base  192  that define a cavity  194  sized to accommodate gears  170 ,  172 ,  180 ,  182  and a portion of the shaft assembly  30 . As shown in  FIG. 7 , the base  192  may have a flanged central aperture  196  sized to receive the lower shaft  42 . In at least one implementation, the housing  160  includes an integral carrier  198  that includes a through-hole  200 , which as will be described below, may be adapted to carry secondary gear assembly  176 . In addition, the housing  160  includes any suitable mounting holes, appurtenances, etc. for receiving and/or retaining other steering input sensor components (e.g., the circuit card  164 , the other secondary gear assembly  174 , etc.), as described more below. 
     At an end opposite the base  192 , the walls  190  define an opening  202  which receives cover  162 . The cover  162  may have a flanged central opening  204  coaxially aligned with aperture  196  in the base  192  so that the upper shaft  40  may couple coaxially with the lower shaft  42  while also protruding from the opening  202  in the cover  162 . The housing  160 , cover  162 , a seal  206  located proximate the flanged opening  204  which circumferentially contacts the outer surface  56  of shaft  40  may inhibit foreign particles such as dust, debris, etc. from interfering with the operation of the gears  170 ,  172 ,  180 ,  182 . 
     As shown in  FIG. 7 , the circuit card  164  may be sized and shaped to fit within the cavity  194  of the housing  160  and may carry two sensing elements  210 ,  212  located on opposite sides  214 ,  216  of the card  164 . In one embodiment, sensing element  210  may be located on the upper side  214  of the card  164 —e.g., facing the first end  52  of upper shaft  40 , and sensing element  212  may be located on the lower side  214 —e.g., facing the second end  92  of lower shaft  42 . In addition as shown in  FIGS. 8-9 , card  164  may be located between gear set  170 ,  180  associated with the upper shaft  40  and gear set  172 ,  182  associated with the lower shaft; e.g., the card  164  may be generally perpendicular to axis S with side  214  facing the upper gear set  170 ,  180  and with side  216  facing the lower gear set  172 ,  182 . Circuit card  164  also may include any suitable embedded or integrated circuitry (not shown)—e.g., to couple the sensing elements  210 ,  212  to ECU  28  via circuit card connector  218 . 
     In at least one embodiment, the circuit card  164  which carries the sensing elements  210 ,  212  may have an aperture therethrough sized to allow rotation of the shaft assembly  30  without interference with the card  164 . Card  164  also may include any suitable fasteners and mounting holes or features for retaining the card  164  within the housing  160 . 
     In the illustrated embodiment, the sensing elements  210 ,  212  are Hall Effect sensors; however, other implementations are possible (e.g., other sensors which may sense using magnetism, electro-magnetism, light, light reflection, etc.). In one implementation, each Hall sensor  210 ,  212  is a single-turn sensor; i.e., each sensor provides a unique electrical output for relative rotation between the sensor ( 210  or  212 ) and a magnetic field about the sensor throughout a turn or range of 0 to 360 degrees. 
     As shown in  FIG. 3 , upper primary gear  170  of the steering input sensor  32  may be carried by the upper shaft  40  and may have an annular-shape with a plurality of teeth  222  extending radially outwardly of a periphery. The gear  170  may have features that correspond with gear retaining features  54  (of upper shaft  40 ). For example, gear  170  may have an inner surface  226  with a number of gaps or voids  228  sized to receive the tabs  66  of the upper shaft  40  when the gear  170  is positioned against the shoulder  70 . In at least the illustrated embodiment, the gear  170  may be held in this position with an annular clip  230  adapted fit within the circumferential channel  68  of the upper shaft  40 ; e.g., so that the gear  170  rotates with and not relative to shaft  40 . Of course, these corresponding features are merely one example; and any suitable features may be used to fix gear  170  against relative rotation with respect to shaft  40  in other embodiments. 
     As best shown in  FIG. 3 , lower primary gear  172  of sensor  32  may be carried by the lower shaft  42  and may have corresponding features similar to those of the upper primary gear (e.g., gear  172  may have teeth  232 , an inner surface  236 , gaps or voids  238 , etc.); e.g., so that the gear  172  rotates with and not relative to shaft  42 . Thus, in at least the illustrated embodiment, gear  172  may be positioned against flange  112  while tabs  114  of lower shaft  42  are received within the voids  238 , and gear  172  may be held in this position with an annular clip  240  located in the circumferential channel  116 . These features are merely exemplary as well; thus, it should be appreciated that any suitable features or means may be employed to fix gear  172  against relative rotation with respect to shaft  42 . In at least one embodiment, the size or diameter of gear  172  is greater than primary gear  170 . 
     As shown in  FIGS. 6 and 9 , the upper secondary gear assembly  174  includes the secondary gear  180  engaged with primary gear  170 , a sensed element  250  carried by gear  180 , a carrier or bracket  252  for positioning the gear  180  within the housing  160 , one or more bushings  254 , and a clip  256 . The gear  180  may be disk-shaped having a plurality of radially outwardly extending teeth  258  meshed with primary gear teeth  222  and may include a central axle  260  extending from one side. The axle  260  may include a circumferential channel  262  near a distal end adapted to receive clip  256 . 
     The sensed element  250  may be surface-mounted, at least partially embedded within, or otherwise fixed to the gear  180 . In at least one embodiment, sensed element  250  is a diametric magnet oriented coaxially with respect to axle  260 . This is merely an example; other implementations are possible (e.g., including other elements which may be sensed using magnetism, electro-magnetism, light, light reflection, etc.). 
     The bracket  252  may be mounted to an interior surface of the housing wall  190  and includes a through-hole  268  adapted to receive bushings  254  on either side. When the axle  260  is located through the bushings  254  and through-hole  268 , the gear  180  may be retained within the bracket  252  by the clip  256  received in the circumferential channel  262 . The shape of the bracket  252  and mounting features thereof are adapted to position the secondary gear assembly  174  in the housing  160  so that the teeth  222 ,  258  of gears  170 ,  180  are intermeshed and so that the sensed element  250  is in a desired location relative to the Hall effect sensor  210  on the upper surface  214  of the circuit card  164 . In this manner, rotation of the gear  180  (and therefore magnet  250 ) will change the properties or characteristics of the magnetic field detected or sensed by sensor  210 . 
     As best shown in  FIGS. 7-8 , the lower secondary gear assembly  176  includes the gear  182  engaged with gear  172 , a sensed element  270  carried by gear  182 , one or more bushings  274 , and an annular clip  276 . In at least one implementation, some components of the lower assembly  176 —as well as their arrangement and assembly—may be the similar to those of the upper assembly  174 ; therefore, some components will not be re-described here, such as the gear  182  (having teeth  278 , an axle  280 , a circumferential channel  282 , etc.), the sensed element  270  (fixed or otherwise carried on side  296  of gear  182 ), the bushings  274 , and the clip  276 . The lower gear assembly  176  may be assembled within the integral carrier  198  in the housing&#39;s base  192 —e.g., using the bushings  274 , gear axle  280 , and clip  276 . When assembled, the teeth  232 ,  278  of gears  172 ,  182  are intermeshed and sensed element  270  is in a desired location relative to the Hall effect sensor  212  on the lower side  216  of the circuit card  164 . Thus, rotation of the gear  182  (and therefore magnet  270 ) will change the properties or characteristics of the magnetic field detected or sensed by the sensor  212 . 
     When shaft assembly  30  (and primary gears  170 ,  172 ) rotates clockwise (CW), the secondary gears  180 ,  182  rotate counter-clockwise (CCW)—and vice-versa. And as the secondary gears  180 ,  182  rotate, changes in the magnetic field are sensed by the Hall effect sensors  210 ,  212  and the sensors  210 ,  212  correspondingly provide electrical output data representative of at least certain magnetic field characteristics. This output data can be provided to the ECU  28  to determine various steering input position and torque information, as will be described in greater detail below. 
     It should be appreciated that each set of gears (e.g., gear set  170 ,  180  and gear set  172 ,  182 ) may have different gear ratios. For example, in at least one embodiment, the gear ratio of gear set  170 ,  180  may be approximately  1 : 1 . 71 , while the gear ratio of gear set  172 ,  182  may be approximately  1 : 2 . In the illustrated implementation, primary gear  172  is larger than primary gear  170 ; however, these and other suitable gear ratios may be achieved in different manners as well. In addition, in other embodiments, other suitable ratios may be used (including, e.g., gear ratios derived from gear  170  being larger than gear  172 ). 
     Turning now to the motorized feedback assembly  34  shown in  FIGS. 2 and 10-12 , the assembly  34  may include a cylindrically-shaped housing  300 , an annular cover  302  adapted to be received within one end  304  of the housing  300 , a gear system  306  located within a cavity  308  of the housing  300 , and a motor assembly  310  adapted to be coupled to a side  312  of the housing  300  at a side aperture  314  thereof along a motor axis M (shown in  FIG. 10 ). The housing  300  may have any suitable mounting features  316  for coupling the motor assembly  310 , the clutch assembly  36 , and/or the steering input sensor  32 . Near one end  318  of the housing  300  (opposite the cover  302 ), the housing may have any suitable features  320  to accommodate the shaft assembly  30  or various shaft components (e.g., including a shaft opening and an in-board circumferential flange sized and shaped to receive annular bearings  326  (bearings shown in  FIG. 3 )). 
     Similarly, the cover  302  may have any suitable features  328  for shaft components (e.g., another inwardly-facing flange sized to receive annular bearings  332 ) (bearings shown in  FIGS. 2-3 ). Bearings  326 ,  332  may be carried by the lower shaft  42  and may space the shaft from the interior walls of housing  300 . The cover  302  may have a hole  334  large enough for the lower shaft  42  to pass therethrough without interference and may be coaxially aligned with the flanged aperture  196  of the steering input sensor housing  160 . As shown in  FIGS. 7 and 10 , the cover  302  may have a circular depression  336  sized and positioned to avoid interference with some components of the secondary gear assembly  176  which may protrude from the base  192  of the housing  160 ; however, this is not required in all embodiments. 
     Within the housing  300 , the gear system  306  may include an annular driven gear  340  carried by the lower shaft  42  ( FIG. 3 ). One face  342  of gear  340  may have any suitable number of axially extending teeth  344  which extend radially outwardly from a gear center (e.g., coincident with axis S). In at least one embodiment, the teeth  344  spiral radially outwardly—e.g., the gear  340  may be an annular bevel gear or a hypoid gear. In addition, a flanged opening  346  of gear  340  may have one or more radially inwardly extending protrusions  348  received within the axially extending groove(s)  124  on the lower shaft  42 . And a retaining clip  350  within circumferential channel  126  may retain the gear  340  adjacent to shoulder  128 . In this manner, gear  340  may be fixed against relative rotation with respect to shaft  42 ; of course, in other embodiments, gear  340  may be fixed against relative rotation in other ways. 
     Gear system  306  further may include a pinion gear  360  ( FIGS. 10-11 ), engaged with the annular gear  340 , that is carried by the motor assembly  310  along axis M, as described below. Gear  360  may have a frustoconical shape, and on an outer surface  362  thereof, may have any suitable number of axially extending teeth  364  (with respect to axis M), and the teeth  364  may be adapted to mesh with teeth  344 . In at least one embodiment, pinion gear teeth  364  also axially spiral about the outer surface  362 —e.g., gear  360  may be a bevel gear or a hypoid pinion gear, just to name a couple non-limiting examples. 
     As shown in  FIGS. 10-11 , the pinion gear  360  is carried by a distal end  370  of a shaft  372  rotatably actuated by a motor  374  of the motor assembly  310 . The motor  374  is carried by a motor housing  378  which is coupled to side  312  of housing  300 ; e.g., the motor assembly  310  may be configured so that when the housings  300 ,  378  are coupled, the teeth  364  of the pinion gear  360  mesh with the teeth  344  of the annular gear  340 . The motor  374  may provide a rotational assistance/resistance profile to shaft assembly  30  via gears  340 ,  360  to provide a force assisting or inhibiting rotation of the steering wheel  38 . The motor  374  may provide such a profile using electrical control signals provided from the ECU  28 , the controller  20 , or both—and the profile may provide the driver with positive feedback consistent non-steer-by-wire systems (e.g., imitating so called ‘road-feel.’). Non-limiting examples of motor  374  include an electric brush motor with brushes, a brushless electric motor, etc. 
     In at least one embodiment, gear system  306  is part of a hypoid gear system—e.g., the teeth  344 ,  346  of both respective gears  340 ,  360  have spiraling features, and as best shown in  FIG. 12 , the axes S and M do not intersect. In this manner, gear system efficiency may be improved—e.g., given the same mechanical output power (from motor assembly  310 ), gears  340 ,  360  may apply more torque to the lower shaft  42  than conventional gear systems or the like. In addition, hypoid gear systems may provide quieter and/or smoother engagement. Of course, a hypoid system  306  is merely one embodiment; other gear systems—including bevel gear systems—may be used instead. 
     Turning now to the clutch assembly  36  shown in  FIG. 2 , the assembly  36  includes any suitable device adapted to selectively inhibit rotation of the shaft assembly  30 —e.g., to provide rotational limits or end stops. For example, clutch assembly  36  may lock or apply a brake to the lower shaft  42 , or perform any similar operation to inhibit rotation thereof. Locking, braking, etc. may be actuated electrically (e.g., using ECU  28 , controller  20 , or both). In one non-limiting example, an end stop may be provided at approximately  1 . 6  steering wheel turns clockwise of center (e.g., approximately 550-600°), and another end stop may be provided at approximately  1 . 6  steering wheel turns counter-clockwise of center. In at least one embodiment, clutch components may be selectively actuated to inhibit lower shaft  42  rotation at the end stops, or any other suitable angular position(s). 
     Assembly of the steer-by-wire assembly  12  may be initiated by positioning the annular gear  340  against shoulder  128  and securing the gear  340  with clip  350 . Thereafter, annular bearings  326 ,  332  may be located on the lower shaft  42 . 
     The torsion assembly  44  then may be located within the cavity  94  of the lower shaft  42  so that the end  140  of the torsion bar  130  is within bore  100  and the sleeve  132  and needle bearings  134  are located within the counterbore  102 . Fastener  148  may be located through aligned lower shaft and bar passages  106 ,  144  retaining or fixing the orientation of the bar  130  with respect to the lower shaft  42 . In one non-limiting example, the fastener  148  may be a press-fit pin; however, other implementations are possible. 
     The lower shaft  42 , gear  340 , and bearings  326 ,  332  may be located within feedback assembly housing  300  and the motor assembly  310  may be coupled to the housing  300  thereby intermeshing the gears  340 ,  360 . The cover  302  may be located over the first end  90  of the lower shaft  42  at end  304  of the housing  300 , and clutch assembly  36  may be coupled to the end  318  of housing  300 , to the lower shaft  42 , or both. With shaft end  90  (and torsion assembly  44 ) protruding from the hole  334  of cover  302 , the lower primary gear  172  may be retained using gear retaining features  108  including clip  240 . 
     Before coupling the steering input sensor housing  160  to the feedback assembly housing  300 , some components of the steering input sensor  32  first may be assembled. For example, secondary gear assembly  176  may be coupled to the integral carrier  198  of housing  160 . Then, the first end  90  of the lower shaft  42  may be positioned through the central aperture  196  of housing  160  thereby intermeshing the teeth  232 ,  278  of gears  172 ,  182 . 
     The circuit card  164  then may be fastened or otherwise secured within the housing  160  thereby spacing the Hall effect sensor  212  proximate to the magnet  270  carried by gear  182 . Then, the upper secondary gear assembly  174  may be coupled to the housing  160  using bracket  252  so that Hall effect sensor  210  (on the upper side  214  of card  164 ) is spaced proximate to magnet  250  carried by secondary gear  180 . 
     Prior to coupling the upper and lower shafts  40 ,  42  to one another, primary gear  170  may be coupled to gear retaining features  54  of the upper shaft  40  (e.g., including being secured in place using clip  230 ). Thereafter, the upper and lower shafts  40 ,  42  may be coupled. This coupling may include intermeshing primary gear teeth  222  with secondary gear teeth  258  while respectively locating keys A and keyways C of upper shaft  40  into keyways D and keys B of the lower shaft  42 . The coupling of upper and lower shafts  40 ,  42  also may include receiving the torsion assembly  44  into cavity  76  (of the upper shaft  40 ) and fixing the torsion bar end  142  relative to the upper shaft  40  using fastener  146  (e.g., placing fastener  146  through upper shaft and bar passages  86 ,  142 ). In at least one implementation, the sleeve  132  is press-fit into cavity  76  (upper shaft  40 )—which, in operation, may provide additional strength to the assembly  12  when an axial force is applied (e.g., to the steering wheel  38 ). 
     In at least one embodiment, the upper and lower shafts  40 ,  42  may rotate relative to one another by a predetermined amount (e.g., 6 degrees). In at least one implementation, the fasteners  146 ,  148  in the torsion bar  130  center the keys A, B within the respective keyways C, D in an untwisted state—e.g., so that the upper shaft  40  may move relative to the lower shaft  42  approximately +/−3 degrees. Thus, when the upper shaft  40  rotates relative to the lower shaft  42 , the torsion bar  130  twists, but twisting and relative rotation of the shafts  40 ,  42  is limited by the interference of the keys A, B, as previously described. Clockwise twisting so that keys A and B are engaged may be associated with a predetermined torque value of the torsion bar  130  (e.g., approximately 6 Newton meters (Nm)); similarly, counterclockwise twisting so that keys A and B are engaged may be associated with a similar predetermined torque value of the torsion bar  130  (e.g., 6 Nm). Of course, less clockwise or counterclockwise twisting (e.g., less than +/−3 degrees) may be associated with correspondingly smaller torque values of torsion bar  130 . 
     To complete the assembly, the cover  162  and seal  206  may be positioned over upper shaft  40  and the cover  162  may be coupled to the housing  160  using fasteners or the like. The steering wheel  38  may be coupled to assembly  12  before, during, or after steer-by-wire assembly  12  is mounted in a vehicle. In some embodiments, the ECU  28  may be mechanically coupled to some portion of assembly  12 ; and in at least one embodiment, the ECU  28  may be part of steering input sensor  32 . In any case, ECU  28  may be electrically coupled to circuit card  164  as well as steering mechanism  14 . 
     It should be appreciated that some assembly steps may be conducted in a different order or concurrently. Further, in other steer-by-wire assembly embodiments, some steps may be added, some steps may be omitted, or both. 
     During operation of the steer-by-wire assembly  12 , in general, steering input may be received at the upper shaft  40  over an exemplary angular steering input range of 1200° (e.g., approximately 3.3-360° turns or +/−600° from a centered position). Steering input at the upper shaft  40  rotates the primary gear  170  in unison, thereby driving secondary gear  180 . And rotation of gear  180  rotates magnet  250  and changes the magnetic field sensed by Hall effect sensor  210 . In response, upper Hall effect sensor  210  provides an electrical output to ECU  28  that corresponds to the angular or rotational orientation or position of gear  180  (i.e., the angular or rotational orientation or position of magnet  250 ). Similarly, the lower shaft  42  and primary gear  172  rotate in response to rotation of the upper shaft  40 —e.g., thereby rotating secondary gear  182  and magnet  270 . As a result, lower Hall effect sensor  212  may provide electrical output to ECU  28  depending on the angular or rotational orientation or position of gear  182  (i.e., the angular or rotational orientation or position of magnet  270 ). The ECU  28  then determines steering position data and steering torque data using the electrical output data of upper and lower sensors  210 ,  212 . 
     More specifically, the ECU  28  determines position and torque data using only two sensors (e.g.,  210 ,  212 ) and two gear sets (e.g.,  170 ,  180  and  172 ,  182 ), whereas conventional systems use three sensors and three gear sets to determine both position and torque data. For example, in conventional systems, a first sensor/first gear set (having a gear ratio GR1) is coupled via a rigid body to a second sensor/second gear set (gear ratio=GR2, where GR1 GR2). Also further, a third sensor/third gear set (wherein gear ratio=GR2) is coupled to the second sensor/second gear set via a torsion bar. In such conventional systems, position data is determined using data sensed via the first and second gear sets, and torque data is determined using data sensed via the second and third gear sets. As described above, assembly  12  uses only two gear sets, each having a different gear ratio (e.g., GR 170,180 ≠GR 172,182 ), to determine both steering position and torque data. In addition, in assembly  12 , the gear sets  170 ,  180  and  172 ,  182  are not coupled via a rigid body, but instead torsion bar  130 . Thus, it should be appreciated that when the torque is at or below a threshold that is sufficient to twist the torsion bar  130 , the the torsion bar  130  behaves as a rigid body and the primary gears  170 ,  172  rotate in phase with one another (e.g., in this scenario, the torsion bar  130  is in an untwisted state). And when torque above the threshold is being applied, rotation of the primary gears  170 ,  172  is out-of-phase with one another (e.g., torsion bar  130  is in a twisted state). As will be explained more below, the untwisted state serves as a baseline when the ECU  28  determines position and torque data—e.g., when any two measurements are received at ECU  28  from sensors  210 ,  212 , initially the ECU  28  may be unable to differentiate whether the torsion bar  130  is in the twisted or untwisted state until executing the method described below. 
     Method  500  shown in  FIG. 16  illustrates a process that may be carried out by the ECU  28  to determine steering position and torque data based on the electrical outputs of sensors  210 ,  212 . The method begins with step  510  that includes the ECU  28  receiving measured electrical values from Hall effect sensors  210 ,  212  (e.g., a pair of measurements S 210(MEAS) , S 212(MEAS) ). It will be appreciated that the method  500  describes determining position and torque data with respect to a single pair of measurements; however, the ECU  28  may receive continuously updated or new pairs of measurements (which may be the same or different than the previous pair), continuously determine steering wheel position and torque data based on the latest pair of measurements, and repeatedly send position and torque data to the steering mechanism  14  based on the determination. 
     Since upper and lower sensors  210 ,  212  may be single-turn devices (as explained above), the electrical values S 210(MEAS) , S 212(MEAS)  may be measured electrical characteristics (e.g., voltages, currents, etc.) that are representative of respective angular measurements between 0° and 360° (herein, for sake of clarity, exemplary measurements are expressed only in terms of degrees instead of, e.g., a voltage). According to one example, ECU  28  could receive a 0.09° measurement from upper sensor  210  (S 210(MEAS) ) and a 234° measurement from lower sensor  212  (S 212(MEAS) ); this pair (0.09°, 234°) will be used to illustrate an ECU determination of position and torque steering data according to one exemplary scenario. For purposes of calculation, one of the sensor measurements S 210(MEAS) , S 212(MEAS)  will be considered a reference sensor output. The method discussed herein considers the lower sensor  212  to be the reference sensor; however, this is not required (e.g., in other embodiments, the upper sensor  210  could be the reference sensor instead). 
     In at least one embodiment, in step  520  (which follows), ECU  28  may normalize the measurements (e.g., 0.09°, 234°) prior to performing additional calculations. As used herein, a normalization or normalizing calculation executed by ECU  28  includes using a mathematical function that correlates values of the desired steering wheel range (e.g., in this case, 1200°) with values less than or equal to a single turn of a Hall effect sensor (e.g., 0°-360°). In at least one embodiment, this is a linear relationship (e.g., see curve  213 ′ of  FIG. 14 , described more below). As shown, y-axis values 0° to 348° of curve  213 ′ correspond to steering wheel x-axis values of the exemplary steering wheel range of 31 600° to +600°. In this implementation, normalization having a maximum y-value of 348° (e.g., instead of 360°) is due to the particular normalization criteria—e.g., the specific steering wheel range) (1200°) and the specific gear ratios (GR 170,180 =1.71 and GR 172,182 =2.00), as well as the criteria that the difference of any pair of sensor values (in the untwisted state) should correlate to a single steering range value, as explained more below. Thus, in other implementations, the maximum y-value could be less than or greater than 348°, but for example, do not exceed 360°. 
     More particularly,  FIGS. 13-14  (which will be referred to more below) depict a first sawtooth waveform (U 210 ) associated with values of the upper sensor  210 —e.g., illustrating cyclical rotations of secondary gear  180  and magnet  250  as detected by sensor  210 . In this implementation, sensor  210  senses rotation of magnet  250  more than five times (or more than five cycles C 210 ) over the 1200° range.  FIGS. 13-14  also depict a second sawtooth waveform (L 212 ) associated with values of the lower sensor  212 —e.g., illustrating cyclical rotations of secondary gear  182  and magnet  270  as detected by sensor  212 . In this implementation, sensor  212  senses rotation of magnet  270  more than six times (or more than six cycles C 212 ) over the 1200° range. It should be appreciated that the corresponding angular measurements of cycles C 210 , C 212  (e.g., depicted along the x-axis) are determinable using the respective gear ratio. For example, the first cycle C 210  extends between −600° and −389.47° (or −600°+360°/1.71), the second cycle extends between −389.47° and −178.95° (or −389.47°+360°/1.71), etc. 
       FIG. 13  also illustrates a normalization curve  213 —determinable by subtracting y-values of waveform U 210  from corresponding y-values of waveform L 212 . The exemplary curve  213  extends along the x-axis from −600° to 600° and along the y-axis between −308° to 348°. And  FIG. 14  illustrates a linear normalization curve  213 ′—wherein, whenever the difference or calculated y-value of curve  213  is less than 0° (i.e., a negative value), 360° is added to the difference—e.g., so that all values of curve  213 ′ result in a y-value of 0° to 348° (and hence a straight line). 
     It should be appreciated that normalization curve  213 ′ may have a non-zero slope—e.g., because the respective gear ratios GR 170,180  and GR 172,182  differ (e.g., if GR 170,180 =GR 172,182 , the slope of curve  213 ′ would be zero—and all y-values would be the same for any given x-value). In at least one embodiment, it is the non-zero slope that facilitates baseline sensor pairs corresponding to only one single steering range value (of course, in the untwisted state). For example, in the illustrated embodiment, when sensor  210  outputs 302.67° and sensor  212  outputs 354° (without applied torque), then according to the normalization curve  213 ′, the steering wheel range equals −423°. Of course, sensor  210  could output 302.67° in five different cycles C 210  along the steering wheel range between −600° and 600°; however, it outputs 302.67° only once when sensor  212  also outputs 354°. 
     Also, it should be appreciated that the illustrated normalization curves  213 ,  213 ′ include a shift so that 0° (y-axis) corresponds with −600° (x-axis); however, this is not required. For example, instead 0° (y-axis) could correspond with 0° (x-axis) or the like—hence, this shift is used for explanatory purposes only. 
     Returning to step  520 , thus ECU  28  may calculate normalized values S 210(NORM) , S 212(NORM)  for each of the measured values (e.g., S 210(MEAS) =0.09°, S 212(MEAS) =234°. For example, 0.09° (upper sensor value) may be converted to 306.09° (S 210(NORM) ) and 234° (lower sensor value) may be converted to 354° (S S212(NORM) ). Since the ECU  28  does not know whether the torsion bar  130  is twisted, the ECU  28  does not assume that the S 210(NORM) , S 212(NORM)  values (e.g., 306.09°, 354°) correspond to a single steering wheel position between −600° and 600°. While method  500  is described with respect to ECU  28  performing normalization calculations, it should be appreciated that a lookup table (e.g., in memory  37 ) could be used instead. For example, normalization calculations could be used to pre-configure lookup table values, and then the values may be stored prior to operation of assembly  12 . Other implementations of step  520  also may exist. 
     In step  530  which follows, the ECU  28  may identify a cycle C 210  or C 212  that corresponds with the normalized values S 210(NORM) , S 212(NORM) . In this manner, the ECU  28  may determine an approximate steering wheel position—e.g., identifying an approximate location along curve  213 ′. For example, once the appropriate cycle C 210  is identified, this information will be used by ECU  28  in calculations described below. Step  530  may include ECU  28  calculating a difference of the normalized values; e.g., 354°−306.09°=47.91° (a y-value of curve  213 ′). For example, in curve  213 ′, y-value 47.91° corresponds with an x-axis value of −434.79°, and −434.79° can be correlated to the first of five cycles C 210  (the first cycle being counted from x-axis value −600°). Of course, when the calculated difference is larger between two normalized measured sensor outputs, ECU  28  instead may identify a different cycle C 210 —e.g., the second cycle, the third cycle, etc. 
     In step  540  which follows, two x-axis offsets (offset 210  and offset 212 ) may be determined using the normalized values of step  520  (e.g., S 210(NORM) =306.09°, S 212(NORM) =354°) and the respectively determined cycle C 210  in step  530  (e.g., in this instance, the first cycle C 210 ). As will be described below, offset 210  and offset 212  will be used to calculate torque and position data. Offset 210  may be a difference between a cycle beginning point C 210(1)  and an x-value along steering range +/−600° that corresponds with y-value S 210(NORM) . And offset 212  may be a difference between the cycle beginning point C 212(1)  and an x-value that corresponds with y-value S 212(NORM) . (Of course, C 211(1) =C 212(1)  in this instance; however, the beginning points of each cycle C 210 , C 212  are not equal elsewhere since GR 170,180 ≠GR 172,182 .) For example, as shown in  FIG. 15 , C 210(1)  is located at −600° and S 210(NORM) =306.09°. The x-value along steering range +/−600° that corresponds with S 210(NORM)  is −421°. Therefore, offset 210 =−421°−(−600°)=179°. Offset 212  can be calculated similarly: S 212(NORM) =354° and corresponds to an x-value along steering range +/−600° of −423°; thus, offset 212 =−423°−(−600°=177°. 
     Next in step  550 , the ECU  28  determines the steering torque data (τ CALC )—e.g., a measure of how much torsion bar  130  is twisted. In at least one embodiment, the ECU  28  determines this torque data by calculating the difference between the two offsets—e.g., τ CALC =offset(upper)−offset(lower) or in the instance example, τ CALC =179°−(177°)=+2° (e.g., the positive sign indicating a clockwise direction). Here, torque is expressed as an angular measurement for sake of clarity (e.g., it should be appreciated that the angular measurement may be converted to Newton-meters, foot-lbs, or like value in accordance with the characteristics of the torsion bar  130 ). Other values and/or directions may be calculated which are greater or lesser than 2°. And of course, if the calculated torque data (τ CALC ) is zero, then no torque is being applied. 
     In step  560 , the ECU  28  may determine whether to adjust the calculated torque data (τ CALC ). For example, the ECU  28  may determine whether the calculated torque (τ CALC ) is a reasonable value—e.g., a value between −3° and +3°. Recall that in the illustrated embodiment, the keys A, B only permit six degrees of rotation (e.g., +/−3°). Thus, if the calculated torque data (τ CALC ) is outside of those bounds, then an adjustment or shift calculation may be necessary (and the method proceeds to step  570  and then step  580 ). If the calculated torque data (τ CALC ) is within the reasonable range, then the method proceeds directly to step  580 . In the present example, since −3°≦2°≦+3°, calculated torque (τ TALC ) equals actual torque (τ ACTUAL ) and the method  500  proceeds from step  560  to  580 . 
     In step  580 , the ECU  28  determines steering position data (ω) using the non-reference sensor output or the output of sensor  210 . Of course, in other embodiments, upper sensor  210  could be the designated reference sensor and step  580  could use the output of sensor  212  instead. Initially in step  580 , an adjusted upper sensor value S 210(ADJ)  is calculated using the actual torque data (τ ACTUAL ) and the associated gear ratio GR 170,180 . More specifically, S 210(ADJ) =S 210(NORM) −(τ ACTUAL * GR 170,180 )=306.09°−(2*1.71)=302.67°. Using the normalization calculation discussed above (step  520 ), the steering position data (ω) then can be determined using the calculated value of S 210(ADJ) , wherein S 210(ADJ))  is a y-value on line U 210  within the cycle determined in step  530  (e.g., in this instance, within the first cycle C 210 ). For example, according to the slope of curve  213 ′, when S 210(ADJ) =302.67°, the corresponding x-value is −423°. Thus, the determined position data (ω)=−423°. Having determined both position data and torque data (e.g., ω=−423°, τ ACTUAL =2°), the method  500  ends. Of course, the torque and position data (ω, τ ACTUAL ) may be transmitted to the steering mechanism  14  so that the vehicle wheels  26  may be actuated accordingly—and this process may be repeated for other sensor values. 
     Step  570  includes determining and executing one of several shift calculations. For example, the shift calculations may account for one of five different scenarios associated with the cycles C 210 , C 212 : (1) when one of the sensor measurements (S 210(NORM) , S 212(NORM) ) falls outside the steering wheel range (e.g., outside of +/−)600°)—e.g., due to applied torque; (2) when the upper sensor measurement (S 210(NORM) ) crosses to an adjacent cycle C 210  in the positive direction (towards +600°); (3) when the upper sensor measurement (S S210(NORM) ) crosses to an adjacent cycle C 210  in the negative direction (towards −600°); (4) when the lower sensor measurement (S 212(NORM) ) crosses to an adjacent cycle C 212  in the positive direction (towards +600°); and (5) when the lower sensor measurement (S 212(NORM) ) crosses to an adjacent cycle C 212  in the negative direction (towards −600°). If any of these circumstances are determined to have occurred, an appropriate shift calculation is applied to determine the actual torque data (τ ACTUAL ). According to one embodiment, each of these scenarios may be determined by determining whether the torque data (τ CALC ) falls within one of five different calculated torque ranges (e.g., each torque range being associated with one of the five possible scenarios). The specific range values will vary depending on calculation criteria—e.g., criteria such as total steering input range, GR 170,180 , GR 172,182 , etc. An example of each scenario is provided below. 
     If the calculated torque data (τ CALC ) falls within a first range (e.g., −27°≦τ CALC ≦−24°), then a sensor measurement has fallen outside the steering wheel range—scenario (1) has occurred. ECU  28  then may perform the following shift calculation to determine the actual torque data (τ ACTUAL ): τ ACTUAL =[S 210(NORM) /GR 170,180 ]−[S 212(NORM) /GR 172,182 ]. Consider the following exemplary sensor output data received at ECU  28 : S 210(MEAS) =56.05° and S 212(MEAS) =240° (e.g., received in step  510 ). Normalization (step  520 ) yields: S 210(NORM) =2.05° and S 212(NORM) =0°. As a result of steps  530 - 550 , the ECU  28  determines the calculated torque data (τ CALC ) to be −26.17°. Since −26.17° falls within the first range, the torque is adjusted using the shift calculation and τ ACTUAL =[2.05°/1.71]−[0°/2.00]=1.20°. Thereafter, step  580  can be performed as described above to determine that the position data (ω)=−600°. 
     If the calculated torque data (τ CALC ) falls within a second range (e.g., 207°≦τ CALC ≦214°), then an upper sensor measurement has crossed to an adjacent cycle C 210  in the positive direction—scenario (2) has occurred. ECU  28  then may perform the following shift calculation to determine the actual torque data (τ ACTUAL ): τ ACTUAL =τ CALC [360°/GR 170,180 ]. Consider the following exemplary sensor output data received at ECU  28 : S 210(MEAS) =39.16° and S 212(MEAS) =288° (e.g., received in step  510 ). Normalization (step  520 ) yields: S 210(NORM) =345.16° and S 212(NORM) =48°. As a result of steps  530 - 550 , the ECU  28  determines the calculated torque data (τ CALC ) to be 208.38°. Since 208.38° falls within the second range, the torque is adjusted using the shift calculation and τ ACTUAL =208.38°−[360°/1.71]=−2.15°. Thereafter, step  580  can be performed as described above to determine that the position data (ω)=−396°. 
     If the calculated torque data (τ CALC ) falls within a third range (e.g., −214°≦τ CALC ≦−207°), then an upper sensor measurement has crossed to an adjacent cycle C 210  in the negative direction—scenario (3) has occurred. ECU  28  then may perform the following shift calculation to determine the actual torque data (τ ACTUAL ): τ ACTUAL =τ CALC +[360°/GR 170,180 ]. Consider the following exemplary sensor output data received at ECU  28 : S 210(MEAS) =57.38° and S 212(MEAS) =304° (e.g., received in step  510 ). Normalization (step  520 ) yields: S 210(NORM) =3.38° and S 212(NORM) =64°. As a result of steps  530 - 550 , the ECU  28  determines the calculated torque data (τ CALC ) to be −210.03°. Since −210.03° falls within the third range, the torque is adjusted using the shift calculation and τ ACTUAL =−210.03°+[360°/1.71]=0.50°. Thereafter, step  580  can be performed as described above to determine that the position data (ω)=−388°. 
     If the calculated torque data (τ CALC ) falls within a fourth range (e.g., 177°≦τ CALC ≦183°), then a lower sensor measurement has crossed to an adjacent cycle C 212  in the positive direction—scenario (4) has occurred. ECU  28  then may perform the following shift calculation to determine the actual torque data (τ ACTUAL ): τ ACTUAL =τ CALC −[360°/GR 172,182 ]. Consider the following exemplary sensor output data received at ECU  28 : S 210(MEAS) =6.50° and S 212(MEAS) =244° (e.g., received in step  510 ). Normalization (step  520 ) yields: S 210(NORM) =312.50° and S 212(NORM) =4.00°. As a result of steps  530 - 550 , the ECU  28  determines the calculated torque data (τ CALC ) to be 180.75°. Since 180.75° falls within the fourth range, the torque is adjusted using the shift calculation and τ ACTUAL =180.75°−[360°/2.00]=0.75°. Thereafter, step  580  can be performed as described above to determine that the position data (ω)=−418°. 
     And finally if the calculated torque data (τ CALC ) falls within a fifth range (e.g., − 183 °≦τ CALC ≦−177°), then a lower sensor measurement has crossed to an adjacent cycle C 212  in the negative direction—scenario (5) has occurred. ECU  28  then may perform the following shift calculation to determine the actual torque data (τ ACTUAL ): τ ACTUAL =τ CALC +[360°/GR 172,182 ]. Consider the following exemplary sensor output data received at ECU  28 : S 210(MEAS) =253.98° and S 212(MEAS) =238° (e.g., received in step  510 ). Normalization (step  520 ) yields: S 210(NORM) =199.98° and S 212(NORM) =358.00°. As a result of steps  530 - 550 , the ECU  28  determines the calculated torque data (τ CALC ) to be −181.00°. Since −181.00° falls within the fifth range, the torque is adjusted using the shift calculation and τ ACTUAL =−181.00°+[360°/2.00]=−1.00°. Thereafter, step  580  can be performed as described above to determine that the position data (ω)=−61°. 
     Thus, one of the first through fifth ranges may be used to determine actual torque (τ ACTUAL ) when the calculated torque (τ CALC ) falls outside of a range of keys A, B—e.g., in the present embodiment, when −3°&gt;τ CALC &gt;+3°. Otherwise, the calculated torque (τ CALC ) equals actual torque (τ ACTUAL ). Having determined the actual torque (τ ACTUAL ) in steps  550 - 570  and the position (ω) in step  580 , the method  500  ends. 
     It should be appreciated that other angular steering input ranges could be used instead. For example, an angular steering range of +/−800° may be used with the same Hall sensors  210 ,  212  by using different gear ratios—e.g., gear set  170 ,  180  and/or gear set  172 ,  182  has a different gear ratio. In at least one embodiment, the normalized waveform may have a different vertical range (e.g., something other than +/−348°), but still may be between 0° and 360°. 
     Other aspects of vehicle steering or steering control/response may be employed using the steer-by-wire system  10  as well. For example, the ECU  28 , the controller  20 , or both may command rotational assistance/resistance in accordance with a determined angular position of the shaft  30 . For example, in order to imitate non-steer-by-wire systems, the motor  374  may be actuated in a direction opposite that applied by at the upper shaft  40 —e.g., applying a predetermined torque thereto. More specifically, the motor  374  may apply torque to the lower shaft  42  using the gear system  306 . This torque may increase as the upper and/or lower shafts  40 ,  42  approach their rotational limits or end stops (e.g., approaching either −600 or +600 degrees), just as a conventional mechanical system becomes more difficult to turn as the steering system approaches its physical limits. 
     In another embodiment, the motor may apply rotational assistance/resistance or so-called ‘road-feel’ in response to torque applied to the upper shaft  40 —e.g., applying torque to shaft  42  in a direction of applied torque or in a direction opposing the torque applied to shaft  40  (e.g., in response to the ECU  28  receiving and processing the outputs of the Hall sensors  210 ,  212 ). For example, in one embodiment, when a relatively small torque is applied to shaft  40 , a small rotational resistance may be applied in the opposing direction, and when a larger torque is applied to shaft  40 , then a correspondingly larger rotational resistance is applied in the opposing direction. Of course, this profile need not be linear (e.g., it could be exponential or any other suitable shape). Rotational assistance or resistance applied by motor  374  may prevent steering from becoming unwieldy, thereby assisting a driver in controlling the vehicle. 
     In at least one embodiment, rotational assistance/resistance applied by motor  374  (and controlled by ECU  28  and/or controller  20 ) may be sufficient to return the steering wheel  38  to the centered position without driver actuation and with minimal overshoot. In fact, in some embodiments, the ECU  28  and/or controller  20  may be able to determine whether a driver is holding the wheel  38 —e.g., by determining upper shaft  40  position in response to attempts by motor  374  to return the upper shaft  40  to the centered position. In at least one embodiment, when it is determined that a driver is not holding the wheel  38 , the ECU  28  and/or controller  20  may command the motor  374  to return the upper shaft  40  to the centered position. 
     It should be appreciated that terms such as upper, lower, above, below, etc. refer to directions in the drawings to which reference is made. These and other like terms are not intended to be limiting, but for explanatory purposes only. 
     Thus, there has been described a steer-by-wire system for a vehicle that includes a steer-by-wire assembly. The assembly includes a steering input sensor that outputs electrical data associated with relative rotational data of an upper shaft and a lower shaft. In response to receiving this data at an electronic control unit (ECU) or a controller, the ECU or controller is configured to determine steering position and torque data for controlling the vehicle wheels. In addition, the steer-by-wire assembly may include a feedback assembly having a motor capable of providing rotational assistance/resistance to the shaft(s) which may assist a driver in steering and controlling the vehicle. 
     While the forms of the invention herein disclosed constitute presently preferred embodiments, many others are possible. It is not intended herein to mention all the possible equivalent forms or ramifications of the invention. It is understood that the terms used herein are merely descriptive, rather than limiting, and that various changes may be made without departing from the spirit or scope of the invention.