Patent Publication Number: US-8537347-B1

Title: Vehicle tire changing system with tool positioning sensor

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The present application is a continuation of, and claims priority from, U.S. patent application Ser. No. 12/106,441 filed on Apr. 21, 2008, which in turn is a continuation in-part of, and claims priority from, U.S. patent application Ser. No. 12/022,315 filed on Jan. 30, 2008, now U.S. Pat. No. 7,495,755, which in turn is a division of, and claims priority from, U.S. patent application Ser. No. 10/783,609 filed on Feb. 20, 2004, now U.S. Pat. No. 7,355,687, which in turn is related to, and claims priority from, U.S. Provisional Patent Application Ser. No. 60/448,679 filed on Feb. 20, 2003. Each of the aforementioned applications is herein incorporated fully by reference. 
    
    
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH 
     Not Applicable. 
     BACKGROUND OF THE INVENTION 
     The present invention related generally to automotive service equipment adapted for the servicing of vehicle wheel assemblies, and specifically to automotive tire changing equipment utilizing positioning and imaging sensors to measure distances, dimensions, and characteristics when servicing a vehicle wheel assembly, and to automate the positioning and movement of the vehicle wheel assembly and associated tools. 
     Typically, tire changers or tire mounting and dismounting systems utilize manual tool positioning systems in which the operator observes the tire and wheel assembly mounted on the tire changer support structure, and manual positions any associated tire service tools, such as a bead breaker arm, based on prior knowledge of the proper methods for servicing a tire. The act of positioning the tire service tool may require a physical action by the operator, such as pulling a lever or sliding a shaft, or the operator may push a button or operate a joystick-type lever for tools which are pneumatically or hydraulically actuated. Either way, the operator is required to exercise judgment to properly place the tire service tools. Hence, the operator may fail to place the tire service tools in their optimum locations as is required for proper functionality and to reduce the chances for wheel damage, tire damage, and tire changer damage. 
     Accordingly, it would be advantageous to provide a vehicle tire mounting (changing) system with sensors configured to acquire dimensional information associated with a vehicle wheel assembly undergoing service, and to utilize the acquired dimensional information to assist in completing a vehicle wheel service procedure by facilitating automated movement of the wheel assembly and associated tire service tools. 
     BRIEF SUMMARY OF THE INVENTION 
     Briefly stated, the present disclosure provides a vehicle tire changing system configured with sensors to acquire dimensional information associated with tire service tools and a vehicle wheel assembly consisting of at least a vehicle wheel rim onto which a tire is to be mounted, dismounted, or repositioned. The sensors acquire dimensional information associated with at least one feature of the vehicle wheel assembly, including, but not limited to, rim diameter, radial runout of the rim bead seat surfaces, lateral runout of the wheel rim, tire characteristics and defects, wheel rim surface defects, wheel rim configurations and profiles, and the presence of installed tire pressure sensors. The vehicle tire changing system is further configured to utilize the acquired dimensional information to automate and monitor the movement of a tire service tool, such as a wheel assembly handling tool or bead breaker arm, to assist an operator in completing a tire mounting, dismounting, or repositioning procedure, and optionally, to store or convey the acquired dimensional information for use by a vehicle wheel balancing system in a subsequent wheel balancing procedure associated with the vehicle wheel assembly. 
     In an embodiment of the present invention, the sensors utilized by the vehicle tire changing system include at least one imaging sensor assembly configured to acquire optical images of the vehicle wheel assembly. The acquired optical images are processed by a processing unit associated with the vehicle tire changing system to identify the dimensional information associated with at least one feature of the vehicle wheel assembly. 
     In an embodiment of the present invention, the sensors utilized by the vehicle tire changing system include at positional sensor associated with a dataset arm which is configured to engage or contact surfaces of the vehicle wheel assembly. Movement and positioning of the dataset arm to contact surface of the vehicle wheel assembly is observed by the positional sensor and monitored by a processing unit associated with the vehicle tire changing system to identify the dimensional information associated with at least one feature of the vehicle wheel assembly. 
     In an embodiment of the present invention, the sensors utilized by the vehicle tire changing system include at positional sensor associated with a tire service tool configured to engage or contact surfaces of the vehicle wheel assembly. Movement and positioning of the tire service tool to engage or contact surface of the vehicle wheel assembly is observed by the positional sensor and monitored by a processing unit associated with the vehicle tire changing system to provide feedback for directing automated movement and positioning of the tire service tool. 
     The foregoing and other objects, features, and advantages of the apparatus and methods of the present invention as well as presently preferred embodiments thereof will become more apparent from the reading of the following description in connection with the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
       In the accompanying drawings which form part of the specification: 
         FIG. 1  illustrates a preferred camera component configuration of the present invention; 
         FIG. 2  illustrates alternate camera component configurations of the present invention; 
         FIG. 3A  illustrates an inner view of a vehicle wheel rim; 
         FIG. 3B  illustrates a side view of a vehicle wheel rim; 
         FIG. 3C  illustrates an outer view of a vehicle wheel rim; 
         FIG. 4  is a perspective view of a tire changing system incorporating a dataset measurement arm; 
         FIG. 5  is a block diagram illustrating the interactive components of a tire changing system of the present disclosure; 
         FIG. 6  is a perspective illustration of the dataset measurement arm of  FIG. 4  in use on the outer rim lip of a wheel rim and tire assembly mounted to the tire changing system; 
         FIG. 7  is a perspective illustration of the dataset measurement arm of  FIG. 4  in use on the outer lip of a wheel rim mounted to the tire changing system; 
         FIG. 8  is a perspective illustration of the dataset measurement arm of  FIG. 4  in use on the outer diameter of a wheel rim and tire assembly mounted to the tire changing system; 
         FIG. 9  is a perspective illustration of the dataset measurement arm of  FIG. 4  in use on the inner bead seat of a wheel rim and tire assembly mounted to the tire changing system; 
         FIG. 10  is a perspective illustration of the dataset measurement arm of  FIG. 4  in use on the inner lip of a wheel rim mounted to the tire changing system; 
         FIG. 11  is a side view of a tire changing system incorporating automated upper and lower bead breaker arms; 
         FIG. 12  is a front view of the tire changing system of  FIG. 11 ; 
         FIG. 13  is a top view of the tire changing system of  FIG. 11 ; 
         FIG. 14  is a top plan view of an automated bead breaker arm incorporating a position sensor; 
         FIG. 15  is a side plan view of the automated bead breaker arm of  FIG. 14 ; 
         FIG. 16  is a perspective view of the automated bead breaker arm of  FIG. 14 ; 
         FIG. 17  is a bottom plan view of the automated bead breaker arm of  FIG. 14 ; 
         FIG. 18  is a back end view of the automated bead breaker arm of  FIG. 14 ; and 
         FIG. 19  is a perspective illustration of rotational movement sensor utilized for monitoring extension and retraction of the automated bead breaker arm of  FIG. 14 . 
     
    
    
     Corresponding reference numerals indicate corresponding parts throughout the several figures of the drawings. 
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     The following detailed description illustrates the invention by way of example and not by way of limitation. The description clearly enables one skilled in the art to make and use the invention, describes several embodiments, adaptations, variations, alternatives, and uses of the invention, including what is presently believed to be the best mode of carrying out the invention. 
     The present invention is described below in the context of an improved vehicle tire changing system, configured with measurement sensors for determining spatial positioning data associated with a vehicle wheel assembly consisting of a wheel rim and any installed tire, secured to the vehicle tire changing system for service, as well as with measurement sensors for determining spatial positioning data associated with one or more actuated tire service tools utilized in the service of the vehicle wheel assembly. 
     Turning to  FIGS. 1 and 2 , one type of measurement sensor which may be utilized with the tire changing system  400  for determining spatial positioning data consists of an imaging sensor assembly  102  configured to acquire one or more images of a field of view. The acquired images are processed to locate, measure distances to, dimensions of, and to identify features or target objects, particularly vehicle wheel assembly features, vehicle wheel feature locations, vehicle wheel configurations, dimensions, and associated distances. For example, an imaging sensor assembly  102  may be disposed to provide data for determining a distance measurement to a tread surface of a tire, a wheel rim bead seat or lip, identifying tire flat spots, bulges, or providing a measure of the tire tread depth. 
     As shown in  FIG. 1 , an imaging sensor assembly  102  preferably consists of an optical energy source  108  configured to emit optical energy at a known wavelength, an imaging sensor  110 , and a lens assembly  112  configured to focus reflected optical energy onto the imaging sensor  110 . The imaging sensor  110  is preferably a two-dimensional array of light sensing elements configured to generate a signal representative of distances between each sensing element and a feature or target object in addition to a signal representative of the optical energy received at each sensing element (i.e., an image consisting of discrete pixels corresponding to each sensing element in the image sensor  110 ). 
     Two or more imaging sensor assemblies  102  may be utilized in conjunction to acquire multiple images of a common target object for purposes of stereoscopic distance measurements. For such embodiments, each imaging sensor  110  may be a conventional two dimensional array of light sensing elements configured to generate a signal representative only of the optical energy received at each sensing element (i.e., an image). 
     As illustrated in  FIG. 2 , the imaging sensor assembly  102  may be configured in a variety of different configuration, depending upon the particular application for which each will be utilized. Preferably, each optical energy source  108  associated with a particular imaging sensor assembly  102  is configured to emit optical energy at the same wavelength. If multiple imaging sensor assemblies  102  are employed in a single vehicle service device  100 , the optical energy sources  108  associated with each imaging sensor assembly  102  may be configured to emit optical energy at different wavelengths, to facilitate distinguishing reflected light between each imaging sensor assembly  102 . 
     Each imaging sensor assembly  102  further includes a conventional communication means  114  to transfer captured images and distance data to a processing unit  116 , such as a central processing unit, a microprocessor, or other suitable logic circuit associated with the vehicle tire changing system  400 . Optionally, image processing may be done in a sensor logic circuit associated with the imaging sensor assembly  102 , and the communication means  114  configured to transfer the resulting processed data along with, or instead of, the raw image data to the processing unit  116 . 
     When associated with vehicle tire changing system  400 , the imaging sensor assembly  102  may be located in a variety of different locations depending upon the particular application for which the imaging sensor assembly  102  is to be utilized, operating parameters of the imaging sensor assembly  102 , including but not limited to durability, stability, focal length of the lens  112 , Field Of View (FOV) of the lens  112 , intensity of optical energy emitted from the optical energy source  108 , and limitations of the imaging sensor  110 . 
     For applications which require the imaging sensor assembly  102  to view a vehicle wheel assembly  118 , consisting of a wheel rim  120  and tire  122 , there are a variety of surfaces on the vehicle wheel assembly  118  which are of interest. For example, as shown in  FIGS. 3A through 3C , with a tire  122  mounted or dismounted, it is desirable to include in a field of view, the inner and outer wheel rim lips  124 ,  134  the inner surface profile  125  of the wheel rim  120 , and the underside  126 A of the inner tire bead seat  128 A. It may be further desirable to include in a field of view, the upper surfaces  130 A,  130 B of the inner and outer tire bead seats  128 A,  128 B with the tire  122  removed or dismounted, as well as the spokes  132  of the wheel rim  120 . The outer portions of the wheel rim  120  may optionally be viewed to locate other features such as a valve stem  136  or temporary index markings so that the wheel assembly  118  may be rotated to a convenient location for inflation or to automatically re-phase the wheel rim  120  and tire  122  during a mounting procedure. 
     For any field of view including a portion of a vehicle wheel assembly  118  acquired by a camera or image assembly  102 , obstructions to the smooth surfaces of the wheel rim  120  such as balance weights (not shown), spokes  132 , or valve stems  134 , may be identified in resulting images utilizing conventional image processing techniques. 
     One suitable location for an imaging sensor assembly  102  to view the surfaces of a vehicle wheel rim  120  as illustrated in  FIG. 3B  is on a tire bead removal arm  300  as shown in  FIG. 4 , associated with the vehicle tire changing system  400 . A tire bead removal arm  300  consists of tire bead breaker or bead roller  302  disposed for rotational movement at an end of an articulating support structure  304 . The articulating support structure  304  is typically configured with mechanical, hydraulic, or pneumatic actuating mechanism (not shown) to engage the bead roller  302  with the side surface of a tire  122  disposed on a wheel rim  120 , disengaging the tire  122  from the wheel rim bead seat  128 A. Typically, a second tire bead removal arm is disposed adjacent an opposite side of the tire  122 , to displace the opposite tire surface from the wheel rim bead seat  128 B. 
     As illustrated in  FIG. 4 , an imaging sensor assembly  102  associated with the tire bead removal arm  300  is preferably coupled thereto by means of a bracket  306  which positions the imaging sensor assembly  102  adjacent the bead roller  302 . In this configuration, the imaging sensor assembly  102  is provided with a field of view which includes the upper surface of the wheel rim bead seat  128 A as the bead roller  302  displaces the tire  122 . Typically, a bead roller  302  will displace a tire  122  two or more inches from the bead seat  128 A. Continuous rotation of the wheel assembly  118  about the wheel axis as the bead roller  302  displaces the tire  122  from the circumference of the bead seat  128 A provides an imaging sensor assembly  102  disposed with the proper field of view, a complete view of the entire circumferential surface of the bead seat  128 A or  128 B from which distance measurements can be acquired. 
     During operation, once the tire bead removal arms  300  have unseated the tire  122  from the bead seat surfaces  128 A,  128 B, the imaging sensor assembly  102  is utilized to acquire distance information corresponding to measurement of the exposed wheel rim bead seat surfaces  128 A,  128 B. For example, as previously described, an imaging sensor assembly  102  associated with the tire bead removal arms  300  can obtain images of the bead seat surfaces  128 A,  128 B from which distance information can be extracted, identifying the presence of radial or lateral runout. 
     Preferably, as illustrated in  FIGS. 4 and 5 , the tire bead removal arms  300  are coupled to a bead roller assembly  402  secured to the base  404  of the tire changer system  400 . A tire clamping device  406  is additionally disposed on the base  404 , and is configured to secure a wheel assembly  118  in a generally horizontal position between the upper and lower tire bead removal arms  300 . An articulating tire mount/demount arm assembly  408  is further coupled to the base  404 , and includes a tire mount/demount head  410  configured to assist in installation or removal of a tire  122  from a wheel rim  120 . A number of conventional accessory items such as a compressed air inflation assembly  412 , tire air inflation ring  414 , a wheel centering support  416 , and removable wheel securing device  418  are associated with the tire changer system  400 . Similar, a number of foot activated control pedals  420  are provided. 
     For some tire and rim combinations it is necessary for the tire changer system  400  to use a high pressure blast of air from the tire air inflation ring  414  between the rim  120  and the tire  122  to assist in seating the tire  122  on the bead seat surfaces  128 A,  128 B. The blast of air causes the tire sidewalls to expand such that the tire  122  makes a seal with the wheel rim  120  close to, if not on, the bead seat surfaces  128 A,  128 B. This is necessary for filling the wheel assembly  118  with air until the tire  122  is seated into the bead seat surfaces  128 A,  128 B. The imaging sensor assembly  102  is optionally utilized to acquire one or more dimensional measurements of the vehicle wheel rim  120  which are subsequently utilized by the tire changer system  400  to determine a need for an air blast, and to alter the position or orientation of the individual nozzles  415  on the tire air inflation ring  414  to accommodate wheel rims  120  of different sizes. 
     In the tire changing system  400 , the vehicle wheel assembly  118  to be dismounted or mounted may be secured on a rotating shaft  401  by a set of wheel clamps  406 . The shaft  401  is driven by a motor drive  436  through a belt  438 . Operation of the motor drive  436  is controlled by a motor control unit  440 , in response to signals received from the CPU  432 . The CPU  432  similarly controls the operation of the wheel clamps  406  through a tire clamp control unit  433 . Mounted on one end of the shaft  401  is a conventional shaft encoder  442  which provides rotational position information to the tire changer CPU  432 . The CPU  432  is preferably capable of executing tire changer operations software and driving an optional display  444 . The CPU  432  is connected to EPROM program memory  446 , EEPROM memory  448  for storing and retrieving non-volatile information such as vehicle wheel specific specifications, and DRAM memory  450  for temporary storage. Manual inputs for the present invention may entail a keypad entry  452  as well as control pedals  420 . 
     Additionally shown in  FIG. 5  is the inclusion of camera control logic  464  in communication with the tire changer CPU  432  for controlling the operation of an imaging sensor assembly  102 . The imaging sensor assembly  102  is preferably disposed with a field of view towards a portion of the wheel assembly  118  mounted on the shaft  401 , such that the imaging sensor assembly  102  can acquire images of the tire and rim surfaces. 
     Optionally, the CPU  432  of the tire changer system  400  is further configured to communicate with one or more additional vehicle services devices, such as a vehicle wheel balancer  200 , to exchange data therewith. For example, the tire changer system  400  may be configured to communicate one or more radial runout measurements acquired by the imaging sensor assembly  102  for a wheel assembly  118  to a vehicle wheel balancer system  200  for use during a subsequent balancing procedure of that wheel assembly  118 . Alternatively, the tire changer system  400  may be configured to store the acquired measurements or images either locally in an associated data storage  450 , remotely over a data network, or in an data storage device associated with the wheel assembly  118  itself such as an radio-frequency identification device (not shown) which can be later accessed by another vehicle service device to retrieve the information. 
     Providing a vehicle tire changing system  400  with one or more tire bead removal arms  300  configured with an associated imaging sensor assembly  102  facilitates automation of the tire bead seat breaking process by utilizing images and distance measurements obtained from the imaging sensor assembly  102  to locate the tire bead removal arms  300  relative to the wheel assembly  118 , and in particular, to locate bead rollers  302  relative to the junction between the tire  122  and wheel rim  120 . The images and distance measurements acquired from the imaging sensor assembly  102  may provide feedback to be utilized by the vehicle tire changing system  400  to control movement of the pair of tire bead removal arms  300 , and to guide the bead rollers  302  into the appropriate junction for displacement of the tire  122  from the bead seat surfaces  128 A,  128 B. Once the bead rollers  302  are positioned, the imaging sensor assembly  102  is utilized along with conventional location and pressure sensors associated with the tire bead removal arms  300  to unseat the tire  122  from the rim bead seat surfaces  128 A,  128 B. 
     In an alternate embodiment, measurement sensors for measuring movement of mechanical components are associated with the articulating features of a mechanical dataset arm  600 , such as shown in  FIGS. 6 through 10 . The mechanical dataset arm  600  incorporates one or more multi-axis joints  602  which can pivot about associated X, Y, and Z-axis, enabling an extendible contact probe  604  disposed on a distal end of the dataset arm  600 , to be moved into contact with a variety of surfaces and points on a vehicle wheel  120  and tire  122  assembly. The extendible contact probe  604  is configured to extend linearly from the main portion  606  of the dataset arm via an extension coupling  608 . These surfaces and points which the probe may be moved into contact with for measurement purposes may include, but are not limited to, an outer (upper) bead seat  128 A of a vehicle wheel  120  and tire  122  assembly as shown in  FIG. 6 , an outer (upper) rim lip  134  as shown in  FIG. 7 , an outer diameter of the tire  122  as shown in  FIG. 8 , an inner (lower) bead seat  128 B of a vehicle wheel  120  and tire  122  assembly as shown in  FIG. 9 , and an inner (lower) rim lip  124  as shown in  FIG. 10 . By predetermining the specific dimensions of the mechanical dataset arm  600  and the contact probe  604 , movement of the dataset arm  600  to bring the contact probe  604  into position to contact a surface of the wheel and tire assembly may be measured by suitable sensors disposed in each multi-axis joint  602 . Those of ordinary skill in the art will recognize that the specific type of measurement sensors associated with each multi-axis joint  602 , if more than one are present, and each extension coupling  608 , if more than one are present, may be varied, provided that movement at the joint (i.e. rotary movement such as axial rotation, or axial movement such as extension and retraction) is monitored to the required degree of precision necessary for conducting service on the wheel and tire assembly. 
     Data from the various measurement sensors associated with the dataset arm is communicated to the CPU  432  of the vehicle tire changing system  400 , and processed to determine three-dimensional positional and/or orientation information associated with the position of the contact probe  604 . Using conventional spatial mapping techniques, the measured position of the contact probe  604 , when in guided into contact with a desired target surface by an operator, may be referenced to a known spatial position, providing relative measurement data. For example, by comparing the measured position of the contact probe  604  with a predetermined point on an axis of shaft  401  about which the vehicle wheel assembly is supported, a radial dimension and spatial position of the vehicle wheel rim  120  may be identified. Similarly, a radial dimension and spatial position of a rim and tire interface may be identified. The CPU  432  may evaluate multiple measured positions of the contact probe  604  to determine additional dimensional and spatial data associated with the secured vehicle wheel assembly  118 , for example, the wheel rim width (i.e., the distance between the inner and outer rim edges  124  and  134 . 
     Those of ordinary skill in the art will recognize that while the contract probe  604  show in the Figures has a generally circular shape and configuration, the specific form of the contract probe may be varied, and that the contact probe  604  may be constructed in any of a variety of configurations and sizes as deemed most suitable for acquiring desired three-dimensional position and/or orientation information. For example, the contact probe  604  may have either a ball, rod, or pointer configuration. 
     The determined dimensional and spatial data associated with the secured vehicle wheel assembly  118  may be subsequently utilized by the CPU  432  in substantially the same manner as described above in connection with dimensional and spatial data determined from image data acquired by an imaging sensor  102 . In particular, the CPU  432  may be configured with suitable operating instructions to utilize the determined dimensional and spatial data for purposes of directing and/or controlling movement of automated articulating tire service tools, such as the tire bead removal arms  300  and/or the articulating tire mount/demount arm assembly  408 . 
     It will be further recognized that a suitable operator interface or keypad  452  may be provided to permit an operator to manually enter dimensional and spatial data associated with the secured vehicle wheel assembly  118  for use by the CPU  432  in substantially the same manner as described above in connection with dimensional and spatial data determined from image data acquired by an imaging sensor  102  or directly by a dataset arm. In particular, the CPU  432  may be configured with suitable operating instructions to utilize the manually entered dimensional and spatial data for purposes of directing and/or controlling movement of automated articulating tire service tools, such as the tire bead removal arms  300  and/or the articulating tire mount/demount arm assembly  408 . 
     Turning to  FIG. 11  through  FIG. 13 , an embodiment of a vehicle tire changing system  500 , which varies in structural configuration from the vehicle tire changing system  400  shown in  FIG. 4 , is shown. The vehicle tire changing system  500  consists generally of a base  502 , and a tire service tool support structure  504 . The base encloses various mechanical and electrical components, such as the CPU  432 , drive motors,  436 , control components, etc. such as shown in  FIG. 5  and previously described. The base  502  further supports a wheel assembly support shaft  506  and associated wheel assembly holding components configured to secure a wheel assembly  118  during a service procedure. 
     The tire service tool support structure  504  incorporates one or more vertical support columns  508  on which automated and articulating vehicle tire service tools, such as upper and lower tire bead removal arms  510 A and  5108 , and an articulating tire mount/demount arm assembly  512  are operatively carried. Each tire bead removal arm  510 A and  510 B is configured for vertical movement about an associated support column  508 . The vertical movement may be driven by any suitable means, including mechanically, pneumatically, or hydraulically. Movement of the tools about a vertical axis is monitored by means of one or more suitable movement sensors, and feedback signals are provided to the CPU  432  from which the current position of each tire bead removal arm  510 A and  510 B is determined, enabling closed-loop positioning and control of the tool position by the CPU  432 . 
     Each articulating and automated tire service tool, such as the upper and lower tire bead removal arms  510 A and  5108 , and the articulating tire mount/demount arm assembly  512 , incorporates a sufficient number of movement sensors to accurately monitor all permissible movements of the tool to a desired level of precision. For example, in addition to monitoring vertical movement about the vertical axis of the tool support shaft  506 , each tire bead removal arm  510 A and  5108  further includes at least one additional sensor configured to monitor horizontal extension and retraction of the removal arms as the bead rollers  302  are moved into operative engagement with a wheel assembly  118  supported on the shaft  506 . Similar sensors are incorporated into the articulating tire mount/demount arm assembly  512  to monitor horizontal extension and retraction of the tire mount/demount head  410  as it is moved into operative engagement with a wheel assembly  118 . Movement of the various tire service tools is monitored by means of one the various sensors, and feedback signals are provided to the CPU  432  from which the current position of each tire service tool is determined, enabling closed-loop positioning and control of the tool position by the CPU  432 . 
     It will be understood that the various sensors may be operatively coupled to the tire service tool external surfaces, in a traditional configuration, or may be enclosed within actuator mechanisms  514  which drive the articulation of the tire service tools. Exemplary sensors include LVDT sensors, optical slides, magnetic slides, potentiometers, hall effect sensors and resistive sensors incorporated into actuators, such as the Polyslide IST actuator assembly produced by the Polygon Company, which incorporates resistive sensing components within a laminate tube to provide data feedback associated with movement of the actuator. Any suitable communications pathway may be utilized to communicate sensor output signals to the CPU  432  during operation of the vehicle tire changing system  500 , including sensor cables or wireless communications. 
     Turning to  FIG. 14  through  FIG. 18 , various views of a tire service tool, and in particular, tire bead removal arm  510 A are shown. Tire bead removal arm  5108 , is not shown, but is essentially a mirror image of tire bead removal arm  510 A. The tire bead removal arm  510 A is secured about the tool support shaft  508  by a sliding member  700 . The sliding member  700  is adapted for vertical sliding movement about the tool support shaft, and consists generally of a tubular segment having a rectangular cross-section matching the cross-sectional configuration of the tool support shaft, which passes axially there through. A housing framework  702  is secured to an external surface of the sliding member  700 , and provides attachment points for an extendible arm  704  carrying the bead roller  302 . The extendible arm  704  is secured for generally horizontal axial movement perpendicular to the vertical axis of the tool support shaft  502  within a sleeve  706  mounted to the housing framework  702 . An actuation mechanism  514  for moving the extendible arm  704  is secured between a first connection point  710  on the housing framework  720 , and a second connection point  712  on the extendible arm  704  in proximity to the bead roller  302 . The actuation mechanism  514  may be any suitable mechanism for driving axial extension and retraction of the extendible arm  704 , any may include, for example, a pneumatic or hydraulically driven cylinder. 
     To monitor the extension position of the extendible arm  704 , and correspondingly, the horizontal position of the bead roller  302 , a sensor capable of measuring the extension and retraction of the actuation mechanism  514  may be incorporated therein, or a separate suitable sensor may secured to the housing framework  702  in operative proximity to the extendible arm  704 . For example, as seen in  FIGS. 17 through 19 , a rotary encoder sensor  714 , consisting of a sensor housing  716 , a rotating shaft  718 , and a offset engagement pin  720  coupled to an plate  722  at the distal end of the rotating shaft may be disposed in the sleeve  706 , and engaged with the extendible arm  704 . Specifically, with the sensor housing  716  secured in a fixed position on the sleeve  706 , the rotating shaft extends towards the extendible arm  704 , such that the offset engagement pin  720  seats within an angled slot  724  in an external surface of the extendible arm  704 . Extension or retraction of the extendible arm  704  results is translated into rotary movement of the rotating shaft  718  of the rotary encoder sensor  714  by the interaction of the offset engagement pin and the angled slot  724 , enabling the sensor  714  to provide an output signal which is representative of the horizontal extension position of the arm  704 . 
     Those of ordinary skill in the art will recognize that similar suitable sensors may be associated with the sliding member  700  to provide an output signal which is representative of the vertical position of the arm  704  relative to the tool support shaft  508 , and that if the tire bead removal arm  510 A is configured for rotational movement about the vertical axis of the tool support shaft  508 , an at least one additional sensor is required to fully determine the spatial position of the bead roller  302 . 
     Output signals from the various position sensors associated with the tire bead removal arm  510 A (and  510 B) are communicated via any suitable means to the CPU  432 , and may be subsequently utilized in a close-loop feedback system for automated articulation and positioning of the bead roller  302 . 
     Preferably, sufficient sensors are disposed in the various tire service tools on the vehicle tire changing system  400  or  500  to provide at least positional information associated with movement along both at least one horizontal axis and at least one vertical axis. These tire service tools may include, but are not limited to a tire bead breaker assembly including an upper bead breaker and a lower bead breaker, or a mount/demount tool for operatively engaging the vehicle wheel assembly to facilitate mounting/demounting a tire from the wheel rim, each of which is configured for automated movement to operatively engage the wheel assembly. 
     The CPU  432  is configured to process the positional information from the various sensors in order to identify the spatial location of the various tire service tools relative to each other. The CPU  432  is further configured to utilize positional and dimensional information associated with a wheel assembly  118  undergoing a service procedure, acquired either via suitable imaging sensors, data set arm movement, or manual input, together with the positional information from the various sensors associated with the tire service tools in order to identify the spatial location of the various tire service tools relative to the wheel assembly  118 . 
     The present invention can be embodied in-part in the form of computer-implemented processes and apparatuses for practicing those processes. The present invention can also be embodied in-part in the form of computer program code containing instructions embodied in tangible media, such as floppy diskettes, CD-ROMs, hard drives, or another computer readable storage medium, wherein, when the computer program code is loaded into, and executed by, an electronic device such as a computer, micro-processor or logic circuit, the device becomes an apparatus for practicing the invention. 
     The present invention can also be embodied in-part in the form of computer program code, for example, whether stored in a storage medium, loaded into and/or executed by a computer, or transmitted over some transmission medium, such as over electrical wiring or cabling, through fiber optics, or via electromagnetic radiation, wherein, when the computer program code is loaded into and executed by a computer, the computer becomes an apparatus for practicing the invention. When implemented in a general-purpose microprocessor, the computer program code segments configure the microprocessor to create specific logic circuits. 
     In view of the above, it will be seen that the several objects of the invention are achieved and other advantageous results are obtained. As various changes could be made in the above constructions without departing from the scope of the invention, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.