Abstract:
A retractable step assist for a vehicle comprises a step, an actuator, an optical fiber sensor, and a safety. The step is movable between a retracted position and a deployed position that is downward and outboard from the retracted position. The actuator is mechanically connected to the step to position the step. The optical fiber sensor has an output that varies when pressure is applied to the optical fiber sensor. The safety is triggered by this output from the optical fiber sensor. The safety is configured to terminate retraction of the step when the optical fiber sensor senses pressure from an object pinched by the step deck.

Description:
RELATED APPLICATIONS  
       [0001]     This application claims the benefit of U.S. Provisional Application No. 60/516,009, filed Oct. 31, 2003, titled RETRACTABLE VEHICLE STEP WITH ANTISTRIKE/ANTI-PINCH SENSOR SYSTEM, which is incorporated herein by reference in its entirety. 
     
    
     BACKGROUND OF THE INVENTION  
       [0002]     1. Field of the Invention  
         [0003]     This invention relates generally to a stepping assist for motor vehicles. In particular, the invention relates to a retractable vehicle step which is movable between a retracted or storage position and an extended position in which it functions as a step assist into the vehicle.  
         [0004]     2. Description of the Related Art  
         [0005]     It is commonly known to add a running board or similar fixed stepping assist to the side of a motor vehicle, especially to a vehicle with a relatively high ground clearance. However, these fixed running boards and other stepping assists have had several drawbacks. First, a fixed running board is often too high to act as a practical stepping assist and is therefore not very effective in reducing the initial step height for the vehicle user. In addition, when using a relatively high running board, the user is likely to hit his or her head while climbing into the vehicle cab. Furthermore, a fixed running board often extends a significant distance from the side of the vehicle, and can be a source of dirt or grime that rubs onto the user&#39;s pants or other clothing as the user steps out of the vehicle onto the ground surface. Such a fixed running board is also frequently struck when the owner of an adjacent parked vehicle opens his door. Finally, a fixed running board or step reduces the ground clearance of a vehicle, and can often be damaged or torn off entirely when the vehicle is used for offroad driving.  
         [0006]     Accordingly, a vehicle step which overcomes the above-stated problems is desired.  
       SUMMARY OF THE INVENTION  
       [0007]     One embodiment of the invention comprises a retractable step assist for a vehicle comprising a step member, an extendable support assembly, an electrically activated actuator, an optical fiber, a light source, a light sensitive optical detector, and an electrically activated safety. The step member has a step deck with an upper stepping surface. The step deck is movable between a retracted position and a deployed position downward and outboard from the retracted position. The extendable support assembly is connectable with respect to an underside of the vehicle so as to extend the step deck downward and outward from the underside of the vehicle in the deployed position. The electrically activated actuator is mechanically connected to the extendible support assembly to automatically position the extendible support assembly and the step deck. The optical fiber comprises an inner core and an outer cladding. The outer cladding at least partially surrounds the inner core. The optical fiber has transmission properties that vary when pressure is applied to the optical fiber. The optical fiber is disposable on a lower body portion of the vehicle. The light source has an optical output optically connected to the optical fiber so as to couple light output by the light source into the core of the optical fiber such that the light propagates through the optical fiber. The light sensitive optical detector is optically coupled to the core of the optical fiber to measure the intensity of the light from the light source propagating through the optical fiber. The intensity measured by the optical detector varies when pressure is applied to the optical fiber. The optical detector has an electrical output dependent on the measured intensity and indicative of the pressure applied. The electrically activated safety is electrically connected to the electrical output of the optical detector. The electrically activated safety terminates retracting motion of the step member when the optical fiber senses pressure from an object pinched between the step deck and the lower body portion.  
         [0008]     Another embodiment of the invention comprises a retractable vehicle step assist comprising a first support arm, a second support arm, a step member, a fiber optic sensor, and a safety system. The first support arm and the second support arm are connectable with respect to an underside of a vehicle so as to be pivotable about a first axis oriented generally parallel to the ground and a second axis oriented generally parallel to the ground, respectively. The step member has an upper stepping surface. The first support arm and the second support arm are connected to the step member so that the first support arm and the second support arm are pivotable with respect to the step member about a third axis and a fourth axis, respectively. The fourth axis is located inboard from the third axis. The first support arm and the second support arm allows the step member to move between a retracted position and a deployed position downward and outboard from the retracted position. At least a portion of the upper stepping surface moves upward as the step member moves from the retracted position to the deployed position.  
         [0009]     The fiber optic sensor is sensitive to pressure. The fiber optic sensor is at least partly disposable in a location of the vehicle upward and inboard from the extended position such that an object pinched by the retracting step member is sensed by the fiber optic sensor. The fiber optic sensor comprises an optical fiber line, a light source, and a light sensitive optical detector. The optical fiber line comprises a core and a cladding. The optical fiber has a transmission loss increasing with pressure applied to the optical fiber. The light source is optically coupled to the optical fiber core to introduce light into the optical fiber. The light inserted in the core propagates along the optical fiber. The light sensitive optical detector is optically coupled to the optical fiber core to sense the light propagating within the core of the optical fiber. The light sensitive optical detector has an electrical output port outputting a signal determined in part by the optical transmission loss of the optical fiber.  
         [0010]     The safety system comprises an electrical switch having an electrical input port connected to the electrical output port of the light sensitive optical detector of the fiber optic sensor. The safety system terminates retraction of the step member when an object is pinched by the retracting step member causing the object to apply pressure to the fiber optic line that introduces transmission loss sensed by the light sensitive optical detector and communicated electronically to the safety system.  
         [0011]     Another embodiment of the invention comprises a retractable step assist for a vehicle comprising a step member, an extendable support assembly, an actuator, an optical fiber, a light source, a light sensitive optical detector, and a safety. The step member has a step deck with an upper stepping surface. The step deck is movable between a retracted position and a deployed position downward and outboard from the retracted position. The extendable support assembly is connectable with respect to an underside of the vehicles so as to extend said step deck downward and outward from the underside of the vehicle in the deployed position. The actuator is mechanically connected to the extendible support assembly to position the extendible support assembly and the step deck. The optical fiber comprises an inner core and an outer cladding at least partially surrounding the inner core. The optical fiber has optical properties that vary when pressure is applied to the optical fiber. The optical fiber is disposable on a lower body portion of the vehicle. The light source has an optical output optically connected to the optical fiber so as to couple an optical signal into the core of the optical fiber such that the optical signal propagates through the optical fiber. The light sensitive optical detector is optically coupled to the core of the optical fiber to sensing the optical signal propagating through the optical fiber. The optical signal measured by the optical detector varies when pressure is applied to the optical fiber. The optical detector has an output that is dependent on the optical signal measured and is indicative of the pressure applied. The safety is triggered by a signal from the optical detector. The safety is configured to terminate retraction of the step member when the optical fiber senses pressure from an object pinched between the step deck and the lower body portion.  
         [0012]     Another embodiment of the invention comprises a method of reducing injury caused by retraction of retractable step in a retractable vehicle step assist. In this method, a fiber optic is disposed with respect to the retracting step to be at least partially compressed when an object is contacted by retraction of the retractable step in a vehicle step assist. The fiber optic has optical properties that are altered when the fiber optic is compressed. Light is propagated through the optical fiber. The light propagated through the optical fiber is detected. Whether the fiber optic is compressed is determined based on the variation in the optical properties of the fiber optic. Retraction of the retractable step is terminated upon compression of the fiber optic.  
         [0013]     Another embodiment of the invention comprises a retractable step assist for a vehicle comprising a step member, an extendable support assembly, an actuator, an optical fiber, a light source, a light sensitive optical detector, and a safety. The step member has a step deck with an upper stepping surface. The step deck is movable between a retracted position and a deployed position downward and outboard from the retracted position. The extendable support assembly is connectable with respect to an underside of the vehicles so as to extend said step deck downward and outward from the underside of the vehicle in the deployed position. The actuator is mechanically connected to the extendible support assembly to position the extendible support assembly and the step deck. The optical fiber comprises an inner core and an outer cladding at least partially surrounding the inner core. The optical fiber has optical properties that vary when pressure is applied to the optical fiber. The optical fiber is disposable on a lower body portion of the vehicle. The light source has an optical output optically connected to the optical fiber so as to couple an optical signal into the core of the optical fiber such that the optical signal propagates through the optical fiber. The light sensitive optical detector is optically coupled to the core of the optical fiber to sensing the optical signal propagating through the optical fiber. The optical signal measured by the optical detector varies when pressure is applied to the optical fiber. The optical detector has an output that is dependent on the optical signal measured and is indicative of the pressure applied. The safety is triggered by a signal from the optical detector. The safety is configured to terminate retraction of the step member when the optical fiber senses pressure from an object pinched between the step deck and the lower body portion.  
         [0014]     Another embodiment of the invention comprises a retractable step assist for a vehicle comprising a step, an actuator, an optical fiber sensor, and a safety. The step is movable between a retracted position and a deployed position that is downward and outboard from the retracted position. The actuator is mechanically connected to the step to position the step. The optical fiber sensor has an output that varies when pressure is applied to the optical fiber sensor. The safety is triggered by the output from the optical fiber sensor. The safety is configured to terminate retraction of the step when the optical fiber sensor senses pressure from an object pinched by the step.  
         [0015]     Another embodiment of the invention comprises a retractable step assist for a vehicle comprising a step member, an extendable support assembly, an electrically activated actuator, an optical fiber sensor, and an electrically activated safety. The step member has a step deck with an upper stepping surface. The step deck is movable between a retracted position and a deployed position downward and outboard from the retracted position. The extendable support assembly is connectable with respect to an underside of the vehicle so as to extend the step deck downward and outward from the underside of the vehicle in the deployed position. The electrically activated actuator is mechanically connected to the extendible support assembly to automatically position the extendible support assembly and the step deck. The optical fiber sensor is disposed as least in part on a lower body portion of the vehicle. The optical fiber sensor outputs a signal that varies when pressure is applied to the optical fiber sensor. The optical fiber sensor is configured to activate the electrically activated actuator which terminates retracting motion of the step member when the optical fiber sensor senses pressure from an object pinched between the step deck and the lower body portion.  
         [0016]     Another embodiment of the invention comprises a method of reducing injury caused by retraction of retractable step in a retractable vehicle step assist. In this method, a fiber optic sensor is disposed with respect to the retracting step to be at least partially compressed when an object is contacted by retraction of the retractable step in a vehicle step assist. Whether the fiber optic sensor is compressed is determined based on the output from the fiber optic sensor. Retraction of the retractable step is terminated upon compression of the fiber optic sensor. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0017]      FIG. 1  is a schematic plan view of a retractable vehicle step system.  
         [0018]      FIG. 2  is a perspective view of the retractable vehicle step system of  FIG. 1 , with the step member in the retracted position.  
         [0019]      FIG. 3  is a perspective view of the retractable vehicle step system of  FIG. 1 , with the step member in the deployed position.  
         [0020]      FIG. 4  is a side view of one embodiment of a retractable vehicle step.  
         [0021]      FIG. 5  is an exploded perspective view of one embodiment of a drive system for use with the step system of  FIGS. 1-3  and/or the retractable vehicle step of  FIG. 4 .  
         [0022]      FIG. 6  is a second perspective view of the drive system of  FIG. 5 , with the gearbox thereof removed for clarity.  
         [0023]      FIG. 7  is a detail view of the drive system of  FIG. 5 .  
         [0024]      FIG. 8  is a second detail view of the drive system of  FIG. 5 .  
         [0025]      FIG. 9  is a third perspective view of the drive system of  FIG. 5 .  
         [0026]      FIG. 10  is a detail view of the gearbox of the drive system of  FIG. 5 .  
         [0027]      FIG. 11  is an exploded view of the retractable vehicle step of  FIG. 4 , connected to the drive system of  FIG. 5 .  
         [0028]      FIG. 12  is a partial sectional view of a motor assembly for use with the drive system of  FIG. 5 .  
         [0029]      FIG. 13  is schematic view of a fiber optic sensor comprising an optical fiber having transmission properties that vary with pressure applied to the optical fiber.  
         [0030]      FIG. 14  is a cross-sectional view of the optical fiber of  FIG. 13  taken along the line  14 - 14 .  
         [0031]      FIG. 15  is a cross-sectional view along a length of optical fiber such as depicted in  FIG. 13  taken along the line  15 - 15  illustrating optical loss induced by applying pressure to the optical fiber.  
         [0032]      FIG. 16  is a side view of one embodiments of a retractable vehicle step having an anti-pinch sensor such as the fiber optic sensor shown in  FIG. 13 .  
         [0033]      FIG. 17  is a cross-sectional view of an embodiment of an optical fiber having a different cross-sectional geometry for use in a fiber optic pressure sensor.  
         [0034]      FIG. 18  is a schematic perspective view of another embodiment of a pressure sensitive fiber sensor. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0035]      FIGS. 1-3  depict one embodiment of a retractable vehicle step system  100 , which may generally comprise a retractable vehicle step  200  mounted adjacent an outboard edge  300  of a vehicle  310 . A drive system  400  may be connected to the vehicle step  200  to provide powered movement of a step member  210  of the vehicle step  200  between a retracted position RP and a deployed position DP. In the depicted embodiment, the step member  210  is movable, under power delivered by the drive system  400 , generally along an inboard-outboard direction between the retracted position RP, in which the step member  210  is partially or completely inboard of the outboard edge, and the deployed position DP, in which the step member  210  is partially or completely outboard of the edge  300 . Accordingly, the step member  210  may serve as a step assist for entering the vehicle when in the deployed position DP.  
         [0036]     The outboard edge  300  may comprise, for example, a lower outboard edge of the vehicle  310 , such as a lower side edge, lower rear edge, or lower forward edge, depending on the mounting location of the retractable vehicle step  200 . Where the edge  300  comprises a lower side edge, the edge  300  is oriented generally parallel to a direction of travel of the vehicle  310 , and the inboard-outboard direction depicted in  FIG. 1  is oriented generally perpendicular to the direction of travel. The direction of travel is typically parallel to the longitudinal axis of the vehicle  310 . Where the edge  300  comprises a lower rear edge or lower forward edge of the vehicle  310 , the edge  300  is oriented generally perpendicular to the direction of travel of the vehicle, and the inboard-outboard direction depicted in  FIG. 1  is oriented generally parallel to the direction of travel.  
         [0037]     The retractable vehicle step  200  may comprise any suitable retractable vehicle step mechanism, of which there are many presently known in the relevant arts. Of course, any suitable later-developed mechanism may also be employed as the retractable vehicle step  200 . In some embodiments, the retractable vehicle step  200  may comprise any of the retractable-step mechanisms disclosed in U.S. Patent Application Publication No. U.S. 2002/0113400 A1 (application Ser. No. 09/817,897), published Aug. 22, 2002, titled RETRACTABLE VEHICLE STEP; or U.S. Patent Application Publication No. U.S. 2003/0184040 A1 (application Ser. No. 10/274,418), published Oct. 2, 2003, titled RETRACTABLE VEHICLE STEP. The entire contents of each of the above-mentioned patent applications and publications are hereby incorporated by reference herein and made a part of this specification.  
         [0038]      FIG. 4  depicts one mechanism that may be employed as the retractable vehicle step  200 . This embodiment of the retractable vehicle step  200  includes a first arm  202  and a second arm  204 , each of which is pivotably connectable via, e.g., a frame  206 , with respect to the underside of the vehicle  310 . (Alternatively, the first and second arms  202 ,  204  may be directly coupled to the underside of the vehicle  310 .) The first and second arms  202 ,  204  are therefore pivotable with respect to the underside of the vehicle about generally parallel first and second axes A-A, B-B, respectively. Each of the first and second axes A-A, B-B is oriented generally parallel to the ground. The step member  210 , which may comprise a stepping deck  212  rigidly connected to a support bracket  214 , is connected to the first and second arms  202 ,  204  so as to be rotatable about third and fourth axes C-C, D-D, respectively. Thus, upon rotation of the first and second arms  202 ,  204  about the first and second axes A-A, B-B, the step member  210  moves between the retracted position RP and the deployed position DP.  
         [0039]     It should be noted that the designation of the outboard arm as the “first arm” and the inboard arm as the “second arm,” and the designation of the various axes ads the first through fourth axes is for convenience only, and any of the arms or axes may be considered a first arm, second arm, first axis, second axis, etc. where these terms are used in the appended claims.  
         [0040]      FIGS. 5-10  depict one embodiment of a drive system  400 . The depicted drive system generally comprises a motor assembly  402  which drives a pinion gear  404 , which in turn meshes with an output gear  406 . The output gear  406  is mounted on and turns an output shaft  408 , which forms a drive end  410  for connecting the drive system  400  to the retractable vehicle step  200 . The pinion gear  404  rotates about a pinion axis F-F and the output gear  406  and output shaft  408  rotate about an output axis G-G.  
         [0041]     In some embodiments, the motor assembly  402  comprises an electric motor  412  which in turn comprises an armature (see  FIG. 12 ) which, when energized, rotates about an armature axis E-E. In certain such embodiments, the internal gearing of the motor assembly  402  is configured to orient a drive shaft  414  (as well as the pinion axis F-F, about which the drive shaft  414  rotates as well) of the motor assembly  402  generally perpendicular to the armature axis E-E. One suitable type of electric motor assembly  402  is a standard automotive window-lift motor, such as those available from Siemens AG of Munich, Germany. Such motors are particularly useful because of their ready availability, low cost, low weight and high reliability. Alternatively, any other suitable type of electric motor may be employed, or a pneumatic or hydraulic motor, or a hand crank may be employed to provide power for the drive system  400 .  
         [0042]     Whether the motor assembly  402  comprises a window-lift motor as discussed above, or some other type of electric or non-electric motor, the speed of the motor  412  itself (e.g. the armature speed where an electric motor is employed) may, in various embodiments, be (i) about 4,500-6,000 RPM, or about 5,000-5,500 RPM, or about 5,300 RPM when unloaded (e.g., with no drive load coupled to the drive shaft  414 ); (ii) about 3,500-5,500 RPM, or 4,000-5,000 RPM, or about 4,500 RPM when deploying a retractable vehicle step (e.g. the step  200  depicted herein) connected with respect to the output gear  406  or output shaft  408 ; and/or (iii) about 2,500-4,500 RPM, or about 3,000-4,000 RPM, or about 3,500 RPM when retracting such a retractable vehicle step connected with respect to the output gear  406  or output shaft  408 . Similarly, the speed of the drive shaft  414 =may, in various embodiments, be (i) about 40-160 RPM, or about 75-125 RPM, or about 90 RPM when unloaded (e.g., with no drive load coupled to the drive shaft  414 ); (ii) about 30-150 RPM, or about 60-120 RPM, or about 75 RPM when deploying a retractable vehicle step (e.g. the step  200  depicted herein) connected with respect to the output gear  406  or output shaft  408 ; and/or (iii) about 15-140 RPM, or about 40-120 RPM, or about 60 RPM when retracting such a retractable vehicle step connected with respect to the output gear  406  or output shaft  408 .  
         [0043]     Where the drive system  400  is employed with a retractable vehicle step similar to that shown in  FIG. 4 , the output shaft  408  may be connected to the upper end of the first arm  202  (see  FIG. 11 ) or the second arm  204 , to drive the arm under power delivered by the motor assembly  402 , and cause it to rotate about the first axis A-A or second axis B-B, thereby moving the step member  210  between the retracted and deployed positions. With the drive system  400  so connected to the retractable vehicle step  200 , the output axis G-G will be substantially coincident with the first axis A-A or the second axis B-B, depending on whether the first arm  202  or the second arm  204  is driven by the drive system.  
         [0044]     Moreover, where the drive system  400  is so connected to a retractable vehicle step  200  of the type shown in  FIG. 4 , and a motor assembly  402  of the type shown in  FIG. 5  is employed, the armature axis E-E will extend generally parallel to the outboard edge  300  of the vehicle. This arrangement is advantageous because in some vehicles more room is available for mounting the retractable vehicle step in the lateral (i.e. generally parallel to the outboard edge  300 ) direction than in the inboard-outboard direction, or in the vertical direction. Accordingly, packaging is improved by mounting the motor assembly  402  such that its armature axis E-E (or, more generally, the long/largest dimension of the motor assembly  402 ) extends laterally (rather than inboard) from the retractable vehicle step  200 .  
         [0045]     In some embodiments, the pinion gear  404  and output gear  406  each comprise helical gears and form a right-angle helical drive. In certain such embodiments, the pinion gear  404  may comprise a 5-tooth helical gear with teeth arranged at a 75-degree helix angle, and/or the output gear  406  may comprise 25-tooth helical gear with a helix angle of 15 degrees. This arrangement facilitates a relatively high gear reduction (5:1) while permitting the gears  404 ,  406  to be of comparable outside diameter (the larger of the two preferably having an outside diameter no more than about 3.0, 2.0, 1.5, 1.2 or 1.1 times that of the smaller). In turn, the output gear  406  may be reduced in size, while preserving a relatively high gear reduction, without requiring an overly small (and weak) pinion gear  404 . Accordingly, in various embodiments, the output gear has outside diameters of less than about 50 mm, less than about 40 mm, or less than about 35 mm. In still another embodiment, the output gear has an outside diameter of about 35 mm.  
         [0046]     Use of a relatively small output gear  406  is beneficial in terms of packaging of the drive system  400 , particularly where the system  400  is connected to a retractable vehicle step  200  of the type depicted in  FIG. 4 , such that the output axis G-G is substantially coincident with the second axis B-B. In such an installation of the system  400 , minimizing the outside diameter of the output gear  406  can minimize the overall inboard protrusion of the retractable step  200 -drive system  400  assembly, or at the very least minimize the inboard protrusion of the upper portions of the step-drive system assembly, nearest the underside of the vehicle  310 , where the available space for installation of these components tends to be most restricted. Moreover, whether the drive system  400  is connected such that the output axis G-G is substantially coincident with the second axis B-B or the first axis A-A, a relatively small output gear  406  improves packaging because of the general scarcity of space in the inboard-outboard and vertical directions.  
         [0047]     Accordingly, in one embodiment the entire drive system  400  fits within a three-dimensional box-shaped space or “package” (with sides oriented at right angles to each other) of about 7.5 inches, or about 7-9 inches (measured along the axis E-E) by about 3 inches, or about 3-4 inches (along the axis F-F) by about 4 inches, or about 4-5.5 inches (along an axis orthogonal to both axes E-E, F-F). In another embodiment, the entire drive system  400  fits within a two-dimensional rectangular “profile” of about 3 inches, or about 3-4 inches (measured along the axis F-F) by about 4 inches, or about 4-5.5 inches (measured perpendicular to the axis F-F). In still another embodiment, the drive system  400  less the motor assembly  402  (in other words, the gearbox  430  with all components connected thereto or installed therein) fits within such a three-dimensional box-shaped space or “package” of about 4 inches, or about 4-5.5 inches (measured along the axis E-E) by about 2 inches, or about 2-3 inches (along the axis F-F) by about 3.5 inches, or about 3.5-5 inches (along an axis orthogonal to both axes E-E, F-F). In yet another embodiment, the drive system  400  less the motor assembly  402  fits within a two-dimensional rectangular “profile” of about 2 inches, or about 2-3 inches (measured along the axis F-F) by about 3.5 inches, or about 3.5-5 inches (measured perpendicular to the axis F-F).  
         [0048]     The gear parameters specified above may be varied in other embodiments. For example, the pinion gear  404  may alternatively have 1, 2, 3, 4, 6, 7, 8 or more teeth, and the number of teeth on the output gear correspondingly varied to achieve the desired gear reduction, which may be 2:1, 3:1, 4:1, 6:1, 7:1 or more. The helix angle of the pinion gear  404  may be varied from the 75-degree angle specified above (as one example, any suitable angle from 45-85 degrees may be employed; other suitable ranges include 60-85 degrees or 70-80 degrees), and the helix angle of the output gear  406  may be selected to complement that of the pinion gear  404 . In still other embodiments, the pinion gear  404  and output gear  406  may comprise bevel gears, standard (non-helical) spur gears, a worm-and-worm-gear arrangement, etc., rather than the right-angle helical drive discussed above.  
         [0049]     In some embodiments, the drive system  400  is configured to have an output speed (the speed of the output gear  406 /output shaft  408 ) of about 10-25 RPM, or about 15-22 RPM, or about 17.8 RPM when unloaded (e.g., without a retractable vehicle step connected with respect to the output gear  406  or output shaft  408 ). In other embodiments, the drive system  400  is configured to have an output speed of about 7-22 RPM, about 12-19 RPM or about 15 RPM when deploying a retractable vehicle step (e.g. the step  200  depicted herein) connected with respect to the output gear  406  or output shaft  408 . In still other embodiments, the drive system  400  is configured to have an output speed of about 4-19 RPM, about 9-16 RPM or about 11.7 RPM when retracting a retractable vehicle step (e.g. the step  200  depicted herein) connected with respect to the output gear  406  or output shaft  408 . Note that when retracting or deploying a retractable vehicle step similar to the step  200  depicted herein, the output speed of the drive system  400  will be equivalent to the angular speed of the first arm  202  and/or second arm  204  as the step  200  deploys or retracts.  
         [0050]     In some embodiments, the drive system  400  is configured to move a retractable vehicle step (such as, without limitation, retractable step similar to the step  200  disclosed herein) from the retracted position RP to the deployed position DP in about 0.3-2.0 seconds, or about 0.5-1.0 seconds. In still other embodiments, the drive system  400  is configured to move a retractable vehicle step (such as, without limitation, retractable step similar to the step  200  disclosed herein) from the deployed position DP to the retracted position RP in about 0.6-1.8 seconds, or about 0.8-1.5 seconds, instead of or in addition to the deployment-time capabilities mentioned above.  
         [0051]     With further reference to  FIGS. 5-10 , the drive system  400  may further comprise a rigid gearbox  430 , which in turn may further comprise a pinion housing  432  connected to (or integrally formed with) an output housing  434 . The pinion housing  432  has a generally cylindrical interior that is substantially centered on and extends along the pinion axis F-F, and the output housing  434  has a generally cylindrical interior that is substantially centered on and extends along the output axis G-G. The pinion and output housings  432 ,  434  intersect in a manner that permits meshing engagement of the pinion and output gears  404 ,  406 , contained therein, respectively.  
         [0052]     The pinion gear  404  is mounted on the drive shaft  414  of the motor assembly and, in the depicted embodiment, forms a number of locking teeth  436  which are received in matching pockets  438  which rotate in concert with the drive shaft  414  under the power of the motor  412 . The teeth  436  and pockets  438  coact to substantially prevent relative rotation of the drive shaft  414  and pinion gear  404  when the drive system  400  is in operation. Alternatively, any suitable structure, such as a spline, keyway, etc. may be employed instead of the teeth  436  and pockets  438  to prevent such relative rotation.  
         [0053]     At its end opposite the motor assembly  402 , the pinion housing  432  forms a bearing pocket  440  which receives an outer race  442   a  of a pinion bearing  442 , while a snap ring  444  retains the bearing  442  in the pocket  440 . An inner race  442   b  of the pinion bearing  442  fits over an axle stub  446  formed on the pinion gear  404 , and is secured thereto with a bearing screw  448 . A dust cap  450  may be employed to prevent debris from entering the pinion housing  432 . In one embodiment, the pinion bearing  442  comprises a radial bearing.  
         [0054]     Accordingly, the pinion bearing  442  journals the pinion gear  404  with respect to the pinion housing  432 , and coacts with the bearing pocket  440 , snap ring  444  and screw  448  to bear any radial (or thrust) loads transmitted through the pinion gear  404  perpendicular to (or along) the pinion axis F-F. The pinion bearing  442 , etc. therefore substantially isolate the motor assembly  402  from such radial or thrust loads and reduce the potential for damaging the motor assembly thereby.  
         [0055]     The output shaft  408  is journalled to the output housing  434  via first and second output bushings  460 ,  462 , with the first output bushing  460  received in an output opening  464  formed in an end plate  466  connected to the end of the output housing  434 . The second output bushing  462  may be received in a similar opening (not shown) at an opposite end of the output housing  434 .  
         [0056]     In one embodiment, a breakaway member  470  is employed to connect the output gear  406  to the output shaft  408 . In the depicted embodiment, the breakaway member  470  comprises a tolerance ring. The breakaway member  470  is disposed between the outside diameter of the output shaft  408  and the inside diameter of the output gear  406 , and prevents relative angular motion of the output gear  406  and the output shaft  408 , except in response to the application of a breakaway torque to the output gear or the output shaft. Such a breakaway torque may be applied when an obstruction blocks movement of the retractable step  200  while the motor assembly  402  is energized and turning, or when an external force is applied to the retractable vehicle step  200  to urge it toward the retracted or deployed position while the motor assembly  402  is stationary.  
         [0057]      FIG. 8  depicts one embodiment of the breakaway member  470  in greater detail. The depicted breakaway member  470  comprises a generally cylindrical spring member which forms a number of longitudinally-extending ridges  472  on its surface. Preferably, the ridges are oriented such that their peaks contact the inside diameter of the output gear  406 ; more generally, the peaks may be oriented such that they contact whichever of the output gear and output shaft is constructed of a softer material. The inherent resilience of the ridges  472  allows the breakaway member  470  to act as a friction coupling between the output gear  406  and the output shaft  408 . Preferably, the breakaway member  470  allows relative rotation of the output gear  406  and the output shaft  408  upon application of a breakaway torque of about 40 foot-pounds to the output gear or the output shaft. One preferred product for use as the breakaway member  470  is a tolerance ring model no. BN, available from USA Tolerance Rings of West Trenton, N.J.  
         [0058]      FIG. 12  depicts one embodiment of the motor assembly  402  in greater detail. The motor  412  comprises an armature  480  rotatably disposed in a space between magnets  482 . A worm  484  extends from one end of the armature  480 , and when energized the armature  480  rotates the worm  484  about the armature axis E-E at the same angular speed as the armature  480  itself. The worm  484  meshes with a worm gear  486 , which rotates about the pinion axis F-F in concert with the drive shaft  414 , which is coupled to the worm gear  486 . The drive shaft  414  delivers power to the downstream portions of the drive system  400 , as described above. Various embodiments of the motor assembly  402  (including without limitation the embodiment depicted in  FIG. 12 ) may employ a gear reduction of about 20:1-180:1, or about 40:1-80:1, or about 80:1, or about 60:1 between the motor  412  itself (e.g., the armature where the motor  412  comprises an electric motor) and the drive shaft  414  of the motor assembly  402 . Accordingly, in the embodiment depicted in  FIG. 12  the worm  484  and worm gear  486  achieve a gear reduction as specified above.  
         [0059]     The retractable vehicle assist may further comprise an anti-pinch/anti-strike system for reducing or preventing injury that might potentially be caused by pinching/striking during retraction of the retractable step. This anti-pinch system may comprise an optical sensor  500  such as a fiber optic sensor as shown in  FIG. 13 . The fiber optic sensor  500  comprises a fiber optic line  502  optically coupled to a light source  504  and a light sensitive optical detector  506 . As illustrated by the cross-sectional view of  FIGS. 14 and 15 , the fiber optic line  502  comprises an optical fiber comprising a core  508  and a cladding  510 . The core  508  is disposed in the cladding  510 . The fiber optic line  502  may further comprise an outer protective sheath  512  surrounding the optical fiber.  
         [0060]     Preferably, the fiber optic  502  is pressure sensitive. For example, pressure applied to the fiber optic  502  may alter one of more optical properties of the optical fiber that are measurable, for example, with the optical detector  506  optically coupled to the optical fiber. In certain preferred embodiments, the optical fiber  502  has a transmission loss that increases with applied pressure. When pressure is applied to a portion of the optical fiber  502 , light escapes from the optical fiber resulting in transmission loss. This transmission loss may be quantified by monitoring the intensity of light propagated down the optical fiber  502  reaching the light sensitive optical detector  506 . Pressure applied to the optical fiber  502  that induces transmission loss thereby reduces the optical signal detected by the light sensitive optical detector  506 .  
         [0061]     In the pressure sensitive optical fiber  502  shown in  FIGS. 14 and 15 , gap regions  514  may be disposed between the core  508  and the cladding  510 . The core  508  may comprise a material having a first refractive index, n core . The cladding  510  may comprise a material having as second refractive index, n cladding . The gap region  514  may be filled with a medium having a third refractive index, n gap . In various preferred embodiments, the cladding  510  comprises a flexible resilient material that is deformable and that has memory, such that the cladding substantially returns to the original shape prior to deformation when a deforming force is removed. The cladding  510  may also comprise material having a refractive index greater than or equal to the refractive index of the core  508  (e.g., n core ≦n cladding ). The medium within the gap regions  514  may have a refractive index smaller than both the refractive index of the core  508  and the cladding  510  (e.g., n gap &lt;n core ≦n cladding ).  
         [0062]     The core  508  may comprise, for example, polymethylmethacrylate (PMMA) or polyurethane as well as other materials. The gap region  514  may comprise an air gap or be filled with other material in other embodiments. The cladding  510  may comprise polyurethane, silicon, polyethylene or rubber such as for example, ethylene-propylene-terpolymer-rubber. Other materials may be employed as well. In various embodiments, the optical fiber  502  may be between about 0.1 to 2.0 meters. Longer or shorter optical fiber  502  may be used in the alternative. The optical fiber core  508  may be, for example, between about 1 millimeter in diameter or larger or smaller in various cases. The optical fiber  502  including the core  508  and the cladding  510  together may be about 1 to 10 millimeters or larger or smaller. Exemplary fiber optic sensors  500  for sensing applied pressure have been developed by Leoni, AG, Nürnberg, Germany.  
         [0063]     As shown in  FIG. 15 , light propagating within the core  508  of the optical fiber  502 , represented by a ray  516  is totally internally reflected off of an interface  518  between the core  508  and the gap region  514 . For total internal reflection, the ray  516  is incident on this boundary  518  at an angle greater than the critical angle. Total internal reflection is possible because the index of refraction of the core  508  is larger than the index of refraction of the gap region  518  (n gap &lt;n core ). Such total internal reflection enables a beam of light to be guided by and propagated through the optical fiber  502 . The optical fiber  502  shown in  FIGS. 14 and 15  includes a large number of such gap regions  514  resulting in total internal reflection and substantially efficient transmission of light down said optical fiber.  
         [0064]     Although the light is totally internally reflected at the interface  518 , a small portion of electromagnetic field strength associated with the light incident on the interface, referred to as the evanescent field, penetrates through the interface. This field strength, however, decays exponentially with a short distance into the gap region  514 .  
         [0065]     Compressive force applied to the optical fiber  502 , illustrated by arrows  520 , causes the cladding  510  to approach or be pressed against the core  508 . The gap regions  514  largely give way bringing the cladding  510  within close proximity to or in physical contact with the core  508  at an optical interface  522 . Preferably, the cladding  510  overlaps the evanescent field. The relatively high index cladding  510  proximal to the core-gap interface  522  and to the evanescent field, permits optical energy to be coupled out of the evanescent field into the cladding  510 . Total internal reflection at the interface  522  between the core  508  and the gap regions  514  is thereby frustrated by the presence of the higher index cladding medium in close proximity to the core-gap boundary and the evanescent field. Coupling light through the interface  522  and into the cladding  510  causes an overall reduction in the amount of light propagated down the optical fiber  502  as light escapes the core  508  and is lost to the cladding. This transmission loss is produced, in this case, by application of pressure to the optical fiber  502 .  
         [0066]     Accordingly, light from the light source  504  is preferably coupled into the optical fiber  502 . This light is propagated along the optical fiber  502  to the light sensitive optical detector  506 , which may measure the intensity of light reaching the optical detector. Without application of compressive force to the optical fiber  502 , preferably a substantial amount of the light coupled into the optical fiber is sensed by the optical detector  506 . Compression of a portion of the optical fiber  502 , such as a result of pinching the fiber optic line causes deformation of the cladding  510  and reduction of the gap regions  514  separating the core  508  and the cladding  510 . Optical energy is coupled from the evanescent field and light escapes the core  508  as a result. This optical loss results in an attenuated intensity level measured by the optical detector  506  as less light is successfully transmitted along the optical fiber  502  to the detector.  
         [0067]     As illustrated in  FIG. 16 , the optical fiber line  502  may be disposed with respect to a lower portion of the vehicle such as on a lower body portion  524 . Preferably, the optical fiber  502  is located such that an object  526  such as a foot pinched by the retracting step member  210  presses against the optical fiber  502 . This applied pressure may be sensed by the optical fiber sensor  500 . The optical detector  506  may have an electrical output port that is electrically connected, for example, to the motor that drives the step member  210 . A signal sent from the detector to a switch controlling the motor may cause the retracting motion of the step to stop. In various embodiments, this signal may possibly trigger the motor to reverse the direction of the step to thereby facilitate release of the object  526 . In other embodiments, sensing pressure may activate a braking mechanism and/or a release for disengaging, e.g., the drive or linkage imposing the force to retract the step  200 .  
         [0068]     Depending on the configuration of the retractable vehicle assist, the optical fiber  502  may be disposed at different locations. Preferably, however, the optical fiber  502  or fibers are positioned on a surface or surfaces that will make contact with an object  526  being pinched by the retracting step  210 . One or more optical fiber lengths  502  may be applied to one or more locations. As shown in  FIG. 16 , the object  526  may, for example, be pinched between the step deck  212  and the lower body panel  524  or, for example, the dust cover. Accordingly, the fiber optic  502  may be connected to the lower body panel  524  or dust cover. Fasteners, adhesives, or other configurations for securing the fiber optic sensor  500  to the vehicle  310  may be used. The fiber optic sensor  500  may be located elsewhere as well. For example, the fiber optic line  502  may be placed on the step deck  212  in certain cases. In various preferred embodiments, the fiber optic line  502  is on the underside of the vehicle and may be on the frame or body of the vehicle or on another auxiliary surface attached to the vehicle. The light source  504  and the optical detector  506  are also preferably secured to the vehicle  310  as well. Electrical power may be supplied to the light source  504  and the detector  506 .  
         [0069]     Still other configurations of vehicle step assists with corresponding fiber optic sensors  500  appropriately placed are possible. The configurations and designs of the retractable vehicle assist, the placement and design of the fiber optic pressure sensor  500 , however, should not be limited to those specifically shown herein. For example, other types of retractable vehicle step assists are described in U.S. Pat. No. 6,641,158 entitled “Retractable Vehicle Step” issued to Horst Leitner on Nov. 4, 2003 and U.S. patent application Ser. No. 10/653,708 entilted “Retractable Vehicle Step” filed Aug. 19, 2003 by Horst Leitner and Anthony Smith, which are incorporated herein by reference in their entirety. These configurations and designs may be employed in whole or in part in conjunction with the anti-pinch systems and pressure sensors. Still other variations are possible.  
         [0070]     Other fiber optic sensor  500  configurations are also possible.  FIG. 17  depicts a cross-sectional view of another embodiment wherein the cladding  510  of the optical fiber  502  has a different cross-sectional geometry. As shown, the gaps  514  between the core  508  and the cladding  510  are created by the cross-sectional shape of the cladding  510  (and the core  508 ). Still other geometries and configuration are possible. In addition, the optical design may be different. For example, the light source  504  and the light sensitive optical detector  506  may be optically coupled to the same end of the optical fiber  502 . A reflective element, disposed proximal to the other end of the optical fiber  502  may be used to return light from the light source along a second pass through the optical fiber  502  back to the detector  506 . This reflective element may comprise, for example, a mirrored surface or fiber Bragg reflector. The light source  504  and optical detector  506  may be located proximal to each other (e.g., together with a central housing) and the optical fiber  502  may be looped to return back to the source/detector location. More than one optical fiber  502  may be coupled to a light source  504  or to an optical detector  506 . More than one light source  504  or optical detector  506  may be used as well. Also, instead of a substantially cylindrical cladding  510  surrounding the core  508 , the cladding may have still other shapes and geometries. In certain embodiments, for example, the cladding  510  may comprise opposed sheets or substantially planar layers or foil above and below the core  508 , which may follow a path that is not necessarily straight as shown in  FIG. 18 .  
         [0071]     Other types of pressure sensitive fiber optic and waveguide sensors  500 , not necessarily based on coupling optical energy in evanescent fields out into the cladding  510  may be employed. Such sensors  500  may or may not have an optical transmission or transmission loss that is altered by applied compressive or other type of force and that is monitored. Other optical properties of the optical fiber  502  or waveguide or system may be also be altered by application of such tactile stimuli and used to sense. Still other types of optical and non-optical pressure sensors may be employed as well. Optical fiber pressure sensors such as described herein, however, are light, compact, relatively inexpensive, and reliable. Moreover, these optical sensors are sensitive. Such sensors preferably can be configured to detect pinching forces less than 100 Newtons (N), less than about 75 N or less about 50 N. Certain design criteria (e.g., the pinching force on a finger in an electric automobile windows) is about 100 N. Preferably, the sensors employed can detect such low forces and may be even more sensitive.  
         [0072]     Although certain embodiments and examples have been described herein, it will be understood by those skilled in the art that many aspects of the devices shown and described in the present disclosure may be differently combined and/or modified to form still further embodiments. Such alternative embodiments of the devices described above and obvious modifications and equivalents thereof are intended to be within the scope of the present disclosure. Thus, it is intended that the scope of the present invention should not be limited by the particular embodiments described above, but should be determined only by a fair reading of the claims that follow.