Abstract:
An adjustable positioning apparatus, which may be used for a foot-operated control, includes a first member that is movably supported with respect to a base, an adjuster that is supported on the first member, and a second member. The adjuster includes a displacement device, an actuator, and a controller. The displacement device includes a first portion that is coupled to the first member, and includes a second portion that is displaced with respect to the first portion. The actuator displaces the second portion with respect to the first portion, and the controller operates the actuator and determines displacement of the second portion with respect to the first portion. The second member is coupled to the second portion.

Description:
FIELD OF THE INVENTION 
   An actuator for an adjustable pedal is used in an automotive vehicle to vary the operating position of a foot pedal that controls a vehicle system, such as the engine throttle, brake system or clutch. 
   BACKGROUND OF THE INVENTION 
   A known adjustable pedal uses an electrical motor to rotate a drive cable that, in turn, rotates a worm gear to adjust the position of a pedal. Other known actuators eliminate the cable and connect the worm gear more directly to a pedal lever. These known systems are believed to suffer from a number of disadvantages, which include large numbers of parts, excessive noise and imprecise output. Another disadvantage of these know assemblies is believed to be the large size requirements within the tight confines of the driver&#39;s footwell. 
   SUMMARY OF THE INVENTION 
   The present invention provides an adjustable positioning apparatus that includes a first member that is movably supported with respect to a base, an adjuster that is supported on the first member, and a second member. The adjuster includes a displacement device, an actuator, and a controller. The displacement device includes a first portion that is coupled to the first member, and includes a second portion that is displaced with respect to the first portion. The actuator displaces the second portion with respect to the first portion, and the controller operates the actuator and determines displacement of the second portion with respect to the first portion. The second member is coupled to the second portion. 
   The present invention also provides an apparatus for adjustably positioning a foot-operated control with respect to a vehicle chassis. The apparatus includes a lever, which is pivotally supported on the vehicle chassis, an adjuster that is supported on the lever, and a pedal. The adjuster includes a threaded rod, a nut, an electric motor, a body, and a controller. The nut cooperatively engages the threaded rod. The threaded rod is supported for relative rotation with respect to the lever arm, and the nut is displaced upon rotation of the threaded rod. The electric motor rotates the threaded rod and includes a plurality of coils. The housing includes a body portion and a coupling portion. The electric motor is disposed in the body portion, which is fixed with respect to the lever. The controller is disposed in the coupling portion and includes a motor driver and a processor. The motor driver provides a drive signal to the plurality of coils, and the processor determines displacement of the nut with respect to the threaded rod based on a feedback signal generated in the plurality of coils during operation of the electric motor. The pedal is fixed to the nut. 
   The present invention also provides an actuator including a threaded rod, a nut, an electric motor, a housing that includes a body portion and a coupling portion, and a controller. The threaded rod extends along an axis. The nut cooperatively engages the threaded rod and is displaced along the axis upon rotation of the threaded rod. The electric motor, which is disposed in the body portion of the housing, rotates the threaded rod and includes a plurality of coils. The controller is disposed in the coupling portion and includes a motor driver and a processor. The motor driver provides a drive signal to the plurality of coils, and the processor determines displacement of the nut with respect to the threaded rod based on a feedback signal generated in the plurality of coils during operation of the electric motor. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The accompanying drawings, which are incorporated herein and constitute part of this specification, illustrate presently preferred embodiments of the invention, and, together with the general description given above and the detailed description given below, serve to explain features of the invention. Like numerals indicate like or corresponding parts throughout the several views. 
       FIG. 1  is schematic view of an adjustable pedal according to a preferred embodiment. 
       FIG. 2  is a isometric view of a preferred embodiment of an adjustable positioning apparatus according to a preferred embodiment. 
       FIG. 3  is an axial longitudinal view of the preferred embodiment of the adjustable positioning apparatus shown in  FIG. 2 . 
       FIG. 4  is a axial end view of the preferred embodiment of the adjustable positioning apparatus shown in  FIG. 2 . 
       FIG. 5  is an exploded isometric view of the preferred embodiment of the adjustable positioning apparatus shown in  FIG. 2 . 
       FIG. 6  is a cross-section taken along line VI-VI in  FIG. 4 . 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
   Referring initially to  FIG. 1 , an adjustable pedal is generally shown at  10 . The adjustable pedal  10  pivots about an axis  12  with respect to a base, e.g., a vehicle chassis, which is schematically indicated at  12   a . The adjustable pedal  10  may be operatively associated with a vehicle system  14  such as an engine throttle control system, a brake system or a clutch. 
   A pedal lever  20  is pivotally supported for rotation about the pivot axis  12  with respect to the vehicle chassis  12   a . In particular, the pedal lever  20  includes a first lever arm  22  that extends from a pivot  24  to a first lever arm end  22   a  operatively connected to the vehicle system  14 . And a second lever arm  26  extends from the pivot  24  to a second lever arm end  26   a . Coupled with the second lever arm end  26   a  is a pedal  28  that is engaged by a foot to operate the pedal lever  20 . 
   Interconnecting a first member, e.g., the pedal lever  20 , and a second member, e.g., the pedal  28 , is an actuator  30  that displaces the pedal  28  relative to the pedal lever  20 . The actuator  30  may include a drive source, such as an electric motor, and may include a linkage, such as a rotary to linear motion converter. Relative displacement is directed by a guide  31 , which may be tubular with a longitudinal slot. U.S. Pat. Nos. 5,722,302 and 5,964,125 and 6,698,309, which show a drive source and a linkage for an adjustable pedal, are hereby incorporated by reference it their entireties. 
   Referring now to  FIGS. 2-6 , there is shown a preferred embodiment of an actuator  30  including an electrically operated motor  32  providing a rotary drive source. The electric motor  32  may sequential move in discrete angular increments, e.g., a stepper motor, or may move in a continuous manner, e.g., a brushless motor. Preferably, the motor  32  rotates a threaded rod  40 , which results in linear displacement of a nut  42  that is cooperatively engaged with the threaded rod  40 . Alternatively, the motor  32  could rotate a nut causing linear displacement of a cooperatively engaged threaded rod. Further, other types of rotary to linear motion converters, e.g., rack and pinion gearing or worm gearing, could be used to displace a pedal  28  with respect to a lever  20 . 
   The motor  32  is preferably constructed with a stator  34  that has a plurality of windings or coils  34   a  (e.g., one of three is shown in  FIG. 6 ) that are angularly spaced around the axis of rotation (e.g., 120 degrees), and an armature  36  that includes a permanent magnet  36   a . As is well understood, sequentially energizing and de-energizing each of the coils  34   a  set up individual magnetic fields that either attract or repulse the permanent magnet  36   a , thereby causing the armature  36  to rotate. At the same time, rotation of the permanent magnet  36   a  induces in the coils  34   a  a current that can be used to determine angular movement, e.g., number of rotations of the armature  34 . The phenomenon that creates this current is commonly referred to as back electromotive force, or back emf. 
   The motor  32  is disposed in a housing  50  that preferably supports the threaded rod  40  for relative rotation. Antifriction devices such as a bearing  52  may be used at the interface of the threaded rod  40  and the housing  50 . The housing  50  preferably includes a body portion  54 , in which the motor  32  is disposed, and a coupling portion  56 , by which the electrical connections are made with the motor  32 . In order to facilitate assembly of the actuator  30 , at least the body portion  54  of the housing  50  may be assembled from more than one piece. As particularly shown in  FIG. 3 , the body portion  54  may preferably be divided into a front piece  54   a  and a back piece  54   b . An insert molded lead frame  58  may be disposed in the bottom of the back piece to make the electrical connections with the coils  34   a.    
   The coupling portion  56  of the housing  50  preferably includes an enclosure portion  56   a  for a controller  60 , and an interchangeable electrical connector portion  56   b , which is preferably detachable with respect to the enclosure portion  56   a . The interchangeable electrical connector portion  56   b  facilitates providing various configurations of electrical contacts to matingly engage different styles of plug connectors. It is envisioned that the body portion  54  and the enclosure portion  56   a  would be universally used, and a particular interchangeable electrical connector portion  56   b  would be selected according to the particular specification of the manufacturer for the vehicle chassis  12   a.    
   The controller  60  that is disposed in the enclosure portion  56   a  of the coupling portion  56  preferably includes an application-specific integrated circuit (ASIC)  62  that can perform at least two functions: 1) driving the coils  34   a , and 2) determining displacement of the pedal  28  with respect to the vehicle chassis  12   a . The first function is commonly referred to as a motor drive circuit. And the second function is performed by a processor based on the number of rotations of the armature  34 , which is determined using back emf, as discussed previously, and the stored knowledge of the thread pitch of the threaded rod  40 . The controller  60  preferably also includes a memory for different operational positions of the pedal  28 , such as for the preferences of different operators of the vehicle. 
   In the event of a loss of the current operational position of the pedal, e.g., due to the motor  32  stalling, the controller  60  detects the stall and adjusts the pedal lever position or shuts down the actuator  30  so as to maintain the existing relationship between the pedal lever  20  and the pedal  28 . When the controller  60  detects stall of the motor  32 , e.g., based on unusual voltage and time characteristics exhibited by the drive circuit, the controller  60  may use an included software program to reset the adjustable pedal  10  by displacing the petal  22  to its extreme positions, as detected by the motor  32  stalling. 
   In operation, a device for adjusting the position of the pedal  28  can be effected by a switch, e.g., a rocker switch, that is manually actuated by the operator of the vehicle, or can be effected by a body controller unit which may interrelate a number of ergonomic and safety adjustments. For example, in the case of a vehicle equipped with a system of airbags, the body control unit may adjust the seat and pedal positions so that an occupant is a prescribed distance from the airbags. 
   An adjustable petal system  10  that uses a body control unit may require as few as three electrical contacts for each actuator  30 : a power contact, a ground contact, and a communication contact. The power and ground contacts supply the power required by the motor  32 , and the communication contact may be connected via a digital serial communication link to the body control unit. In the case of a manual switch, two additional contacts may be required to connect the actuator  30  with the wire from the increase spacing pole of the switch and with the wire from the decrease spacing pole of the switch. 
   Incorporating a controller  60  that is mounted directly on the actuator  30  provides the present invention with a number of advantages. First, the present invention eliminates a separate controller that is additionally mounted on the chassis and then additionally connected to the actuator  30 . Second, by virtue of having self-contained processing power, the present invention eliminates the need to draw processing capacity from other preexisting processors, e.g., engine control unit. Third, by virtue of the controller  60  processing the back emf signals from the coils  34   a , the present invention eliminates the need for additional motor rotation sensors, e.g., an array of Hall effect sensors, which add cost, complexity and size. Fourth, by virtue of the controller  60  processing the back emf signals from the coils  34   a , the present invention eliminates at least four wires from the wiring harnesses connecting the actuator  30 . Fifth, the interchangeable electrical connector portion  56   b  of the present invention facilitates the universal applicability of the actuator  30  while providing an easy manner of adapting to varying styles of electrical plug connectors. 
   While the present invention has been disclosed with reference to certain preferred embodiments, numerous modifications, alterations, and changes to the described embodiments are possible without departing from the sphere and scope of the present invention, as defined in the appended claims. Accordingly, it is intended that the present invention not be limited to the described embodiments, but that it have the full scope defined by the language of the following claims, and equivalents thereof.