Patent Publication Number: US-2017368890-A1

Title: Tire monitor

Description:
TECHNICAL FIELD 
     This disclosure relates to measuring or approximating tire wear. 
     BACKGROUND 
     U.S. Pat. No. 8,625,105 to Pryce discloses an apparatus that measures the tread of a tire on a vehicle, in which a laser line generator generates an elongate pattern of light. Mirrors are arranged to reflect light from the laser line generator onto the rolling surface of the tire. Mirrors are arranged to reflect light from different regions of the rolling surface of the tire towards a camera. The camera images the regions of the rolling surface of the tire. The apparatus may be hand-held or arranged such that a tire to be aged is driven onto or over it. 
     U.S. Publication No. 2015/0330773 to Uffenkamp discloses a device for measuring the tread depth of a tire including measuring modules situated transversely with respect to the running direction of the tire and connected to a shared evaluation device. Each measuring module includes (i) an illumination device which is configured and situated in such a way that during operation it projects at least one light line onto the tread to be measured, and (ii) at least one image recording device recording at least one image of at least one area of the tread to be measured. The at least one illumination device and the at least one image recording device are configured and situated in such a way that the illumination direction of the illumination device and the image recording direction of the image recording device are oriented neither in parallel to one another nor orthogonally with respect to the tread. 
     U.S. Pat. No. 6,069,966 to Jones discloses a method and apparatus for automotive tire condition and other article assessment based upon radiation analysis of a rotated tire. Analysis of reflected radiation on the basis of intensity sensing provides a measure of tread depth and sidewall profile, together with tread location and other data. By positional analysis of the tread depth locations there is provided complementary information on the tread wear pattern. Sidewall profile determination enables identification of other tire condition factors. Tread depth and sidewall profile are also determined by laser or other radiation line image displacement techniques and a mounting system is provided for the apparatus enabling determinations to be made without the use of a roller bed. Proper positional alignment of the wheel to the apparatus is determined by means of a reference datum derived from reflected radiation within the apparatus. Proper defined proximity of the tire is defined by a pair of alignment bars positioned over an optical window of the apparatus. 
     U.S. Pat. No. 7,538,864 to Golab discloses a vehicle wheel alignment sensor for a machine-vision vehicle wheel alignment system comprising a scanned beam camera incorporating an illumination source, a means for deflecting light emitted by the illumination source along a path within a field of view, and a detector array for receiving illumination reflected from objects within the field of view to generate an image which is representative of a region of interest within the field of view. 
     SUMMARY 
     In various embodiments, the present disclosure includes a vehicle having: a tire monitor, located in a wheel arch and configured to: project beam(s) onto a tire, measure reflection(s) of the beam(s); memory, processor(s) configured to, based on the reflection(s): build a two-dimensional (2D) profile of the tire, compare depths of the built profile to depths of a preloaded profile, assess tire wear based on the comparison. 
     In various embodiments, the present disclosure includes a method of monitoring a tire with a vehicle including a tire monitor located in a wheel arch, memory, and processor(s), the method comprising: with the tire monitor: projecting beam(s) onto a tire, measuring reflection(s) of the beams; with the processor(s) and based on the reflection(s): building a two-dimensional (2D) profile of the tire, comparing depths of the built profile to depths of a preloaded profile, assessing tire wear based on the comparison. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       For a better understanding of the invention, reference may be made to embodiments shown in the following drawings. The components in the drawings are not necessarily to scale and related elements may be omitted, or in some instances proportions may have been exaggerated, so as to emphasize and clearly illustrate the novel features described herein. In addition, system components can be variously arranged, as known in the art. Further, in the drawings, like reference numerals designate corresponding parts throughout the several views. 
         FIG. 1  is a block diagram of a vehicle computing system. 
         FIG. 2  is a top view of a vehicle including the vehicle computing system. 
         FIG. 3 a    is a top view of a tire. 
         FIG. 3 b    is a two-dimensional profile of the tire taken across segment  303  of  FIG. 3   a.    
         FIG. 4  is a side view of the vehicle including a tire monitor. 
         FIG. 5  is a three-dimensional lookup table. 
         FIG. 6  is a block diagram of a turning routine. 
         FIG. 7  is a block diagram of a search routine. 
     
    
    
     DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS 
     While the invention may be embodied in various forms, there are shown in the drawings, and will hereinafter be described, some exemplary and non-limiting embodiments, with the understanding that the present disclosure is to be considered an exemplification of the invention and is not intended to limit the invention to the specific embodiments illustrated. 
     In this application, the use of the disjunctive is intended to include the conjunctive. The use of definite or indefinite articles is not intended to indicate cardinality. In particular, a reference to “the” object or “a” and “an” object is intended to denote also one of a possible plurality of such objects. Further, the conjunction “or” may be used to convey features that are simultaneously present instead of mutually exclusive alternatives. In other words, the conjunction “or” should be understood to include “and/or”. 
       FIG. 1  shows a computing system  100  of an example vehicle  200 . The vehicle  200  includes a motor, a battery, at least one wheel driven by the motor, and a steering system configured to turn the at least one wheel about an axis. Suitable vehicles are also described, for example, in U.S. patent application Ser. No. 14/991,496 to Miller et al. (“Miller”) and U.S. Pat. No. 8,180,547 to Prasad et al. (“Prasad”), both of which are hereby incorporated by reference in their entirety. In various embodiments, the vehicle  200  includes four wheels, each wheel having a corresponding tire  300 . 
     The computing system  100  enables automatic control of mechanical systems within the device. It also enables communication with external devices. The computing system  100  includes a data bus  101 , one or more processors  108 , volatile memory  107 , non-volatile memory  106 , user interfaces  105 , a telematics unit  104 , actuators and motors  103 , and local sensors  102 . 
     The data bus  101  traffics electronic signals or data between the electronic components. The processor  108  performs operations on the electronic signals or data to produce modified electronic signals or data. The volatile memory  107  stores data for immediate recall by the processor  108 . The non-volatile memory  106  stores data for recall to the volatile memory  107  and/or the processor  108 . The non-volatile memory  106  includes a range of non-volatile memories including hard drives, SSDs, DVDs, Blu-Rays, etc. The user interface  105  includes displays, touch-screen displays, keyboards, buttons, and other devices that enable user interaction with the computing system. The telematics unit  104  enables both wired and wireless communication with external processors via Bluetooth, cellular data (e.g., 3G, LTE), USB, etc. The actuators/motors  103  produce physical results. Examples of actuators/motors include fuel injectors, windshield wipers, brake light circuits, transmissions, airbags, the steering, etc. The local sensors  102  transmit digital readings or measurements to the processor  108 . Examples of suitable sensors include temperature sensors, rotation sensors, seatbelt sensors, speed sensors, cameras, lidar sensors, radar sensors, the disclosed tire monitor(s), etc. It should be appreciated that the various connected components of  FIG. 1  may include separate or dedicated processors and memory. Further detail of the structure and operations of the computing system  100  is described, for example, in Miller and/or Prasad. 
     It should be appreciated that the vehicle  200  is configured to perform the methods and operations described below. In some cases, the vehicle  200  is configured to perform these functions via computer programs, such as a tire monitoring program, stored on the various volatile or non-volatile memories of the computing system  100 . In other words, a processor is configured to perform a disclosed operation when it is in operative communication with memory storing a software program with code or instructions embodying the disclosed operation. Further description of how the processor, memories, and programs cooperate appears in Prasad. It should further be appreciated that a nomadic device, such as a mobile phone, in operative communication with the vehicle  200  may alternatively or in addition perform some or all of the methods and operations discussed below by querying the sensors of the vehicle  200 . 
       FIG. 4  generally shows and illustrates a tire monitor  400  consistent with the present disclosure. The tire monitor  400 , in conjunction with the tire monitoring program stored on the memory  106 ,  107  and/or executed on the processor  108 , is configured to: (a) monitor tire treads, (b) monitor ride height, and (c) confirm presence of the tire. The tire monitor  400  includes beam emitter(s)  401  and beam receiver(s)  402 . As shown in  FIG. 4 , the tire monitor  400  is fixed underneath a wheel arch  404  of the vehicle  200  and is configured to scan or monitor a tire  300  of the vehicle  200  as the vehicle  200  travels along a road  403 . It should be appreciated that the vehicle  200  may include one tire monitor  400  in each wheel arch  404 . In various embodiments, to save cost, the vehicle  200  includes a single tire monitor  400 . The data from the single tire monitor  400  serves as a representative sample for all tires of the vehicle  200 . In various embodiments, to save cost, the vehicle  200  includes a single tire monitor  400  per axle. 
     With reference to  FIG. 4 , the beam emitter(s) (also referred to as emitter(s))  401  project beam(s) of light  405 , some of which reflect off the tire along incident segment  407 . The incident segment  407  of  FIG. 4  extends into the page along a width dimension of the tire  300 . The incident segment  407  is approximately straight, but may include some bends due to the depths of tire grooves  302 . The reflected beam(s)  406  proceed to beam receiver(s) (also referred as receiver(s))  402 . It should be appreciated that other optical devices (e.g., cameras) may be used instead of emitter(s) and receiver(s). It should be appreciated that emitter and receiver technology is known in the art and is regularly applied in dimensioning depths of tire treads and tire grooves. In various embodiments, the tire monitor  400  includes a range-finder  408 , also located under the wheel arch  404 , configured to measure the vertical distance or range  409  between the tire  300  and the wheel arch  404 . Range-finders  408  are commercially available and are known in the art. Some range-finders determine range by projecting and receiving beam(s) of light. 
       FIG. 3 a    generally shows and illustrates top view of the tire  300 . The tire  300  includes treads  301   a ,  301   b ,  301   c ,  301   d , and  301   e . The tire defines grooves  302   a ,  302   b ,  302   c , and  302   d  between the treads  301 . The tire  300  of  FIG. 3 a    is an example and it should be appreciated that the disclosed systems and methods may be applied to any suitable tire with a pattern of treads  301  and grooves  302 . 
     The tire monitoring program applies data reported from the tire monitor  400  to measure or dimension the a two-dimensional profile  305  of the top of the tire  300  along profile segment  303 . More specifically, the tire monitoring program is configured to apply data generated by the receiver(s)  402  and the range finder  408  to map or profile a depth of the treads  301  and the grooves  302  along profile segment  303 . In various embodiments, the receiver(s) and the range finder  409  report a magnitude and/or an angle of the reflected beam(s)  406  to the processors  108  and/or the memory  106 ,  107 . The tire monitoring program applies software to convert one or more of the reported magnitude(s), the angle(s), and the range  409  into the two-dimensional profile  305 . In various embodiments, the software adjusts the depths associated with the tire treads  301  and grooves  302  according to the range  409  reported by the range finder  408 . In various embodiments, the total width of the projected beam(s)  405  exceeds a total width of the tire  300  by a predetermined amount (e.g., 10%, 20%, or 30%) so that the incident segment  407  can span across and cover an entire width of the tire  300 , even when the tire  300  is turned or angled. 
       FIG. 3 b    shows a generated two-dimensional profile  305 . The top vertical profile  305  includes heights or depths of the treads  301  and/or the grooves  302  extending in a direction parallel to depth  409  and perpendicular to profile segment  303 . The two-dimensional profile  305  generated by the tire monitor program includes widths extending in a direction parallel to profile segment  303 . More specifically, and as shown in  FIG. 3 b   , each of the treads  301  and the grooves  302  has a width. The tire monitoring program is configured to group recorded depths into a series of widths. For example, the tire monitoring program may begin from the left side of the tire  300  and group all vertical dimensions falling within a predetermined percentage (e.g., 5% or 10%) of each other into a first width, corresponding to tread  301   a . The tire monitoring program may then recognize depths falling outside of the predetermined percentage. The tire monitoring program may now group all vertical dimensions falling within a predetermined percentage of each other into second width, corresponding to groove  302   a . The tire monitoring program may repeat this process until all treads  301  and all grooves  302  have been mapped or profiled (and thus generating a complete two-dimensional profile  305 ), such that each tread  301  has a depth and a width and each groove  302  has a depth and a width. It should be appreciated that for the purposes of this disclosure, the terms depth, height and vertical distance are synonymous (unless context indicates otherwise) as applied to the tire treads and the tire grooves. These vertical measurements may be relative to each other, relative to a baseline, or relative to the wheel arch  404 . 
     Under ideal conditions, the incident segment  407  will be perpendicular to the radius of the tire  300 . Vehicle wheels (and thus tires) turn during steering. Tire turn will cause the incident segment  407  to skew (i.e., angle) with respect to the radius of the tire  300 . As shown in  FIG. 3 , skew may result in an improper profile segment  304 . Skew will degrade the quality and reliability of the two-dimensional profile  305 . 
     In various embodiments, the tire monitoring program compares the determined widths of the treads  301  and/or the grooves  302  to preloaded widths of a preloaded or manufacturer-specified two-dimensional profile  305 . When the determined widths match the preloaded widths within predetermined boundaries, then the tire monitoring program confirms that the tire  300  is straight and the incident segment  407  is perpendicular to the radius of the tire  300 . In other words, the tire monitoring program is configured to discard measurements that generate groove and treads widths that mismatch the preloaded widths. In various embodiments, tire turn will cause corrupt or extraordinary (i.e., nonsensical) measurements. These corrupt or extraordinary measurements will also be discarded. As explained below, it should be appreciated that discarded measurements/profiles may first be referenced by the search algorithm before being discarded (e.g., to confirm that a new measurement is an improvement over a previous mismatched/corrupted measurement). 
       FIG. 3 a    shows an example skewed profile segment  304  resulting from a skewed incident segment  407 . Because the incident segment  407  is skewed, the widths of each treads  301  and grooves  302  may be expanded (i.e., too wide). After generating a two-dimensional profile  305  corresponding to the skewed profile segment  304 , the tire monitoring program may compare the determined widths of treads  301  and grooves  302  to the preloaded widths. Under this scenario, because the determined widths will exceed the preloaded widths, the tire monitoring program will eventually discard the two-dimensional profile  305  corresponding to the skewed profile segment  304 . It should be appreciated that a comparison of each tread  301  and/or groove  302  is unnecessary and that the comparison can be performed with reference to a width of a single tread  301  (e.g., tread  301 ) and/or a width of a single groove (e.g., groove  302   c ). In various embodiments, the tire monitoring program compares the width of each tread  301  and/or groove  302  to the preloaded widths, and confirms the tire  300  as straight when a predetermined confirmation number (e.g., one, two, etc.) of widths match the preloaded widths. The term “match” as used in the specification and claims encompasses matching within certain predetermined boundaries or limits, e.g., the measured value is within 1%, 5%, etc. of the expected value. 
     In various embodiments, the wheel monitor program is configured to, upon user selection and/or a schedule and/or detecting park, perform a turning routine to turn the wheels (and thus the tires  300 ) until the determined widths match the preloaded widths. Because each of the wheels may be permanently offset with respect to the other wheels, the wheel monitor program may execute this process once for each wheel. For example, the wheel monitor program may begin with the front left wheel and turn the wheel until the determined widths of the front left tire  300  match the preloaded widths. Once this occurs, the wheel monitor program saves the two-dimensional profile  305  of the front left tire  300  having the matching widths and turns to another wheel, such as the front right wheel. The wheel monitor program repeats the process with respect to the front right tire  300 . In various embodiments, the wheel monitor program is configured to only enable performance of the turning routine when the vehicle is detected to be in park. 
     As stated above, the turning routine involves turning the wheels until the determined widths of a tire  300  match the preloaded widths. In various embodiments, the turning routine proceeds as follows: First the turning routine compares the determined widths to the preloaded widths. If the determined widths fail to match the preloaded widths, then the turning routine causes the vehicle  200  to turn the wheel in a first direction. The turning routine then compares newly determined widths to the previously determined widths. If the newly determined widths are closer to the preloaded widths than the previously determined widths, then the turning routine continues turning the wheel in the first direction. The turning routine continues turning the wheel until the determined widths match the preloaded widths. 
     If, however, the newly determined widths exceed the previously determined widths or a corrupt or extraordinary result is returned, then the turning routine causes the vehicle  200  to turn the wheel in a second, opposing direction. The turning routine causes the vehicle  200  to turn the wheels in the second direction until the determined widths match the preloaded widths. It should thus be appreciated that the turning routine may perform a search algorithm that compares one or more of newly determined widths, previously determined widths, and preloaded widths until the newly determined widths match the preloaded widths. 
     As stated above, the turning routine does not need to compare the width of each tread  301  and groove to each preloaded width. Instead, the turning routine can select representative a width of treads  301  (e.g., tread  301   c ) and/or a representative width of grooves (e.g., groove  302   c ). If a two-dimensional profile  305  generated according to the turning routine is extraordinary (e.g., fails to contain any treads  301  or grooves  302 ), then the turning routine may turn the tire  300  until the determined two-dimensional profile  305  sufficiently corresponds to the preloaded two-dimensional profile, and then execute the above search. 
     Eventually, the wheel monitor program generates a suitable two-dimensional profile  305  with widths matching the preloaded widths of the preloaded two-dimensional profile  305 . The wheel monitor program now compares the vertical dimensions of the suitable two-dimensional  305  against preloaded vertical dimensions of the preloaded two-dimensional profile  305 . 
     As the tire  300  contacts the road  403 , friction will erode the treads  301 , reducing the vertical height of the treads  301  with respect to the grooves  302 . Additionally, objects may become embedded in the threads  301  and/or the grooves. These embedded objects will increase/obscure/corrupt a vertical dimension along profile segment  303 . For example, an embedded object may reflect projected beam  405  backward, away from receiver  402 , thus causing a gap or absence of information for one or more of the treads  301  and the grooves  302 . 
     The tire monitoring program thus compares a determined depth or vertical dimension (e.g., height) of each tread  301  to one or more preloaded depths or vertical dimensions of each tread  301 . When the vertical dimension of a tread  301  and/or a groove  302  exceeds an upper preloaded vertical dimension by a predetermined degree, then the tire monitoring program marks the tread and/or groove as damaged with an embedded object. When the vertical dimension of a tread  301  and/or a groove  302  is less than a lower preloaded vertical dimension by a predetermined degree, then the tire monitoring program marks the tread as being worn. When the vertical dimension of a tread  301  and/or a groove  302  cannot be determined, then the monitoring program marks the tread and/or the groove as unknown. The tire monitoring program is configured to display the status of each tread and/or groove  302 . When the vertical dimensions of a predetermined wear number of treads and/or grooves are worn and/or unknown, the monitoring program instructs the vehicle  200  to issue an alert or trigger a vehicle alarm. The alert may be an electronic message sent over the telematics  104  to the mobile device. 
     It should be appreciated that various factors such as load on the tire, tire temperature, and tire pressure influence the vertical and/or horizontal dimensions of the treads  301  and the grooves  302 . In various embodiments, the monitoring program selects the preloaded two-dimensional profile  305  from a set of preloaded two-dimensional profiles. 
       FIG. 5  represents the set of two-dimensional profiles assembled into a cube  500 . The cube  500  includes many pre-loaded two-dimensional profiles  305 . Each preloaded two-dimensional profile  305  has an X coordinate  503   a , a Y coordinate  501   a , and a Z coordinate  502   a . To select a preloaded two-dimensional profile  305 , the monitoring program must determine proper coordinates  503   a ,  501   a , and  502   a  respectively along the X axis  503 , the Y axis  501 , and the Z axis  502 . Each axis  501 ,  502 , and  503  corresponds to a different factor. For example, the X axis  503  may correspond to tire temperature, the Y axis  501  may correspond to tire pressure, and the Z axis  502  may correspond to load on the tire  300 . 
     The cube  500  may be loaded based on a model number of the tire. For example, the non-volatile memory  106  may store one cube  500  for each acceptable tire  300 . When a new tire  300  is installed on the vehicle, the user may input the model of the tire  300  into the monitoring program (e.g., via the user interface  105 ) and the monitoring program may select a cube  500 . The monitoring program continues to reference the selected cube  500  until the user specifies a newly installed tire  300 . 
     The tire monitoring program may receive information from the local vehicle sensors  102  to select the proper X, Y, and Z coordinates  503   a ,  501   a , and  502   a . For example, as the tire temperature changes, the tire monitoring program may adjust the X coordinate  503   a . As the tire pressure changes, the tire monitoring program may adjust the Y coordinate  501   a . As the load or weight on the tire changes, the tire monitoring program may adjust the Z coordinate  502   a . Digital tire load sensors, tire temperature sensors, and tire pressure sensors are individually known in the art. In various embodiments, the range  409  measured by the range-finder  408  is used to approximate tire load. Once the tire monitoring program has selected the proper X, Y, and Z coordinates  503   a ,  501   a , and  502   a , the tire monitoring program selects a corresponding preloaded two-dimensional profile  305 . 
     Moisture may impair or obscure dimensions measured by the wheel monitor  400 . In various embodiments, the wheel monitor  400  includes a moisture sensor mounted to the underside of the wheel arch  404 . The monitoring program may discard two-dimensional profiles  305  (or decline to generate the two-dimensional profiles  305 ) when the moisture sensor senses a certain level of moisture. 
     As stated above, the vehicle  200  applies the tire monitor  400  to confirm the presence of a tire. More specifically, the range finder  408  periodically measures the range  409  when the vehicle is in park. When the range increases by more than a predetermined degree (e.g., by more than 20%), the tire monitoring program assumes that the tire  300  is absent. The tire monitoring program now instructs the vehicle  200  to issue an alert or trigger a vehicle alarm. The alert may be an electronic message sent over the telematics  104  to the mobile device. 
       FIG. 6  generally shows and illustrates an example turning routine  600  executed by the wheel monitoring program. In various embodiments, the wheel monitoring program only executes the turning routine  600  when the vehicle has been in park for at least a predetermined amount of time. In various embodiments, the wheel monitoring program only executes the turning routine  600  within a certain time window (e.g., a schedule set by the user via the user interface  105 ). At block  602 , the tire monitor  400  projects the beam(s)  405 . At block  604 , the tire monitor  400  receives the reflected beam(s)  406 . Simultaneously with one or more of blocks  602  and  604 , the tire monitor  400  finds the range  409  at block  606 . 
     The tire monitor program collects data generated by the tire monitor  400  and builds a two-dimensional profile  305  at block  608 . At block  610 , the tire monitor program loads factors (e.g., tire load, tire temperature, tire pressure, etc). At block  612 , the tire monitor program selects a preloaded two-dimensional profile  305  via the cube  500 . At block  614 , the tire monitor program compares the determined width(s) of the treads  301  and/or the grooves  302  to the preloaded width(s). 
     If block  614  results in a match, then the tire monitor program saves the two-dimensional profile  305  and compares each depth of the measured two-dimensional profile  305  to the preloaded two-dimensional profile  305 . If a depth is corrupt (e.g., extraordinary) or above a first constant, K 1 , then the tire monitor program assigns a first flag, flag 1 , to the groove/tread at block  622 . If the depth is normal, or between the first constant and a second constant, K 2 , then the tire monitor program assigns a second flag, flag 2 , to the groove/tread at block  624 . If the depth is worn or less than the second constant K 2 , then the tire monitor program assigns a third flag to the groove/tread at block  626 . 
     The various flags cause the tire monitor programs to display different alerts via the user interface  105 . For example, the first and third flags may cause the tire monitor program to automatically issue an unprompted alert via the user interface  105 . It should be appreciated that each constant is derived from and associated with the preloaded two-dimensional profile  305  and may change depending on the specific tread and/or groove (e.g., tread  301   c  may have different constants than tread  301   d ). 
     If block  614  results in a mismatch or a corrupt result, then the tire monitor program executes the search routine at block  616 . After performing the search routine, the tire monitor program discards the mismatched or corrupt two-dimensional profile  305 . 
       FIG. 7  generally shows and illustrates an example search routine  616 . At block  702 , the tire monitor program  400  determines whether block  614  returned a mismatch or a corrupt result. A mismatch is a result that resembles the correct result within coarse limits or boundaries (e.g., the widths are 20% wider than expected). A corrupt result is a nonsensical or extraordinary result (e.g., only a single width is found when the tire has 10 treads and 9 grooves). 
     If the result is corrupt, the search routine  616  proceeds to block  704  where the orientation of the tire  300  is reset to a first orientation. If the result is a mismatch, then the routine proceeds to block  706  where the wheel is turned a first degree, Turn  1 , in a first direction, D 1 . At block  706 , the routine repeats steps  602 ,  604 ,  606 ,  608 , and  614  (collectively referred to as “the comparison”). It should be appreciated that the search routine  616  performs the comparison at each block of  FIG. 7  associated with a turn and a direction. 
     At block  706 , if the new profile  305  better matches the preloaded profile  305  than the previous profile  305 , then the search routine proceeds to block  722 . If the new profile  305  more poorly matches the preloaded profile  305  than the previous profile  305 , then the search routine proceeds to block  708 . It should generally be appreciated that the search routine  616  ends when one of the comparisons is a match. It should generally be appreciated that each previous profile  305  is discarded at block  618  after the previous profile  305  has been used in the comparison. 
     At block  722 , the search routine  616  turns tire the first degree in the first direction and executes the comparison. If the comparison is better, then the search routine  616  continues executing block  722  until the comparison yields a worse result (i.e., a new profile  305  more poorly matches the preloaded profile  305  than the previous profile  305 ). 
     When the comparison becomes worse, the search routine  616  refines the search at block  724 . More specifically, the search routine causes the wheel to turn a second degree, Turn  2 , in a second direction, D 2 . The second direction is opposite the first direction. After block  726 , the search routine  616  performs the comparison. Block  728  shows that the search routine  616  continues until a newly measured profile  305  matches the preloaded profile  305 . The search routine  616  may continue in block  728  by executing the refining process associated with blocks  722  and  724  for block  726  (i.e., repeating block  726  until a worse profile  305  is measured, and then refining the search by turning a third degree, Turn  3 , in the first direction, D 1 , the third degree being less than the second amount). 
     At block  708 , the search routine  616  causes the wheel to turn the first degree, D 1 , in the second direction, D 2 . If the new profile  305  is worse, then the search routine  616  causes the tire to reset at block  710 . The reset of block  710  may be a reset to a different position than the reset of block  704 . A reset at block  710  may cause the search routine  616  to end and issue a corresponding warning via the user interface  105 . 
     If the new profile  305  is better, then the search routine proceeds to block  712 . The above disclosure related to blocks  722 ,  724 ,  726 , and  728  applies to blocks  712 ,  714 ,  716 , and  718 .