1. Field of the Invention
This invention generally relates to foot orthotics and more specifically to a method and apparatus for delivering to a consumer a footbed that takes into account several criteria including the plantar surface topography of each of the consumer's feet.
2. Description of Related Art
Over the years many companies have endeavored to produce a footbed that provides improved support for an individual's foot. Each method involves two basic phases, namely: a measurement phase, a production-delivery phase. The measurement phase involves a use of apparatus for obtaining meaningful measurements of the foot, particularly the topography of the plantar surface. The production-delivery phase involves the conversion of the results of the measurement phase into physical footbeds and the delivery of the finished footbeds to the consumer.
In the gold standard and dominant methodology used by medical personnel, the measurement phase requires the formation of a plaster cast and mold. A practitioner produces a plaster cast of each foot after manipulating each foot to the referenced neutral position subject to compensation for any observed anatomical deformities of that foot. The non-weight bearing condition exists when no forces are applied to the foot, as when the foot is suspended in air.
The production-delivery phase begins when the practitioner sends these casts to a laboratory. Laboratory personnel make a mold from the cast and then use personnel, information, a priori knowledge of the practitioner's procedures and other experiences to modify the molds. Then laboratory personnel use each mold to form a corresponding orthotic block which is finished at the laboratory and returned to the practitioner as an orthotic footbed.
After receipt, the practitioner dispenses the orthotic footbed to the patient. If a patient reports only little or no relief or reports discomfort, the practitioner must reevaluate the patient. If changes to the orthotic footbed are required, then either the entire process must be repeated or the orthotic footbed must be sent back to the laboratory with instructions for additional corrections.
As will be apparent, the measurement phase for this approach requires professional personnel. Production and delivery occurs generally by transporting the foot model to a production facility and returning the orthotics to the practitioner. As a result while this approach produces a very good orthotic, it is costly and involves significant delays between the measurement phase and the completion of the production-delivery phase.
U.S. Patent Application Pub. Nos. US2006/0283243 and US2006/0247892 (2006) to Peterson, and both assigned to the assignee of this invention, disclose an alternative method and apparatus for manufacturing custom footbeds corresponding in quality to those produced by the gold standard approach. During a measurement phase a scanner with an air cushion and related equipment produce a topographical map of the bottom of each foot while the foot is in a semi-weight bearing state and in the neutral position; i.e., a semi-weighted, supported, aligned position. The air cushion captures the foot in this position and measures the distances corresponding to the spacing between a reference plane and the bottom of the foot. A manufacturing facility converts these measurements into information by which a computer numerically controlled machine produces a custom orthotic insert.
This approach eliminates the need for producing and transporting a foot model to a manufacturing site. However, the measurement phase still requires professional personnel to position the individual's foot on the scanner. The production-delivery phase still involves the time to manufacture and transport the footbeds to and from a central manufacturing site.
Consequently, while these footbeds are less expensive to manufacture than those by the gold standard, they are not economically feasible for use by a large number of individuals who have no significant foot abnormalities, but would benefit from such footbeds. To overcome this characteristic, several companies have developed systems with the expectation of providing a consumer with a shoe or footbed in which the costs involved with the measurement and production-delivery phases are minimized.
U.S. Pat. No. 5,237,520 (1993) to White discloses one such foot measurement and footwear sizing system. During a measurement phase, a consumer stands on a scanner at a retail store. The scanner derives three-dimensional topographical information about the consumer's feet. During the manufacturing-delivery phase, this three-dimensional information is processed to identify a matching manufactured footwear product that can be sent to a retail store for delivery to a customer. This shipment includes a last for use in subsequent manufacturing of custom footwear and footwear products at the retail store.
U.S. Patent Application Pub. No. 2007/0039205 (2007) to Erb et al. discloses two embodiments of a patient station or kiosk used during the measurement phase. In one, a foot measurement device is replicated on a floor and a vertical surface. In the other, the measuring device is on the floor only. Measurement devices include an optical scanner and a sensor for measuring pressure. Information derived from the measurement devices is converted into a shoe prescription that a store representative uses to construct a pair of shoes during the production-delivery phase. During this phase, additional structural adjustments to achieve consumer comfort may be necessary.
Erb et al. also disclose a method and system for identifying a kit of footwear components for assembly into customized footwear for a consumer. Specifically, the scanned foot measurements and other consumer provide a basis for printing a “prescription” by which a selection is made from a set of prefabricated footwear components.
U.S. Patent Application Pub. No. US2002/0138923 (2002) to Shaffeeullah discloses a method and apparatus for producing individually contoured shoe inserts at a local site. More specifically, apparatus at the local site a scanner generates data representative of the shape of the foot. This data is processed based upon characteristics of the consumer's foot, qualities the consumer desires and the manner in which the consumer walks. After the measurement phase ends, the modified data then transfers to a device for forming an insert by molding a blank template at the local site to produce a desired shape during the production-delivery phase. This system is disclosed as being operated by an individual other than the consumer. Moreover, although this system may minimize the time to complete the production-delivery phase, the replication of insert production apparatus at each local site can increase the production-delivery phase costs significantly.
Erb et al. patent could reduce the time and cost to the measurement and production-delivery phases. However, there is a possibility that the resulting in custom footwear may not be acceptable to the consumer. Specifically, in this system the foot is not aligned and is not in a supported position when the scanning occurs. Rather, in the Erb et al. patent a system, preferably with a foam mat, deforms under the weight of the individual. Thus scanning occurs when the foot is in a fully compensated position with the arch flattened and the foot elongated. Moreover, as feet generally are not symmetrical in the full compensated position because one foot may flatten more than the other so the feet are determined to be different sizes when, in fact, they are not. Although a system in accordance with Erb et al. might eliminate the need for a professional during the measurement phase, there is recognition that a consumer may be directed eventually to a podiatrist or other professional. The time and costs for the production-delivery phase are reduced because the shoe is assembled at the retail store. However, the retail store must bear the additional costs for a large inventory of shoe lasts and other components in order to minimize delivery time. Further, the actual time and cost during this phase are somewhat uncertain because the consumer determines when the shoes are acceptable. This is a very subjective test.
The White patent and Shaffeeullah applications disclose systems that could minimize the time and costs of one phase. However, they do not minimize the time and costs for both phases.
With respect to apparatus for performing the measurement phase, in the above-identified Peterson published applications a consumer sits and places a foot on an air pillow to be captured in a reference neutral position with the forefoot and midfoot locked against the rear foot. Then the air cushion is inflated until the practitioner notices that the heel lifts from a reference plane. When this occurs, the system scans the bottom of the foot. This scanning process produces accurate representations of the bottom topography of a consumer's feet and enables the production of accurate footbeds.
In the previously identified White patent, a white light scanner generates information about the bottom topography of a consumer's foot, apparently when the consumer is standing on the scanner. Reflected light is processed to obtain a pressure map based on the color of the reflected light and to obtain distance based on light intensity.
In U.S. Pat. No. 5,790,256 (1998) to Brown et al. matrices of pressure sensors and optical sensors measure feet in a full-weight bearing state. A digital signal processor normalizes and smoothes pressure data for display on a monitor. Other optical devices located around the perimeter of each foot measure the length, width and height of the foot. The data from both these sensor sets and devices is then manipulated to display orthotic prescriptions or insole selection information for use in the manufacture of footwear or footbeds.
U.S. Pat. No. 6,141,889 (2000) to Baum discloses a custom foot support and method for producing such a foot support based upon a scan of the foot in a full-weight, semi-weight or non-weight bearing state. An optical scanner produces a three-dimensional image of the bottom of the foot. The images from this scanner are then exported to a central system for use in the production of a footbed, along with data relating to the patient's sex, weight, age, foot type and shoe style. Some of this data is taken from tables based upon averages. It is unlikely that a modification based upon an average will produce the exact modification the patient requires.
U.S. Pat. No. 7,068,379 (2006) to Sundman et al. discloses an optical contoured digitizer for scanning a foot that provides laser scanning at a reduced cost. Specifically, the optically contoured digitizer includes a radiation source. A first mirror folds the emitted radiation toward an object being measured, such as a foot in a full-weight bearing state. A second mirror folds the reflected radiation to a sensor.
U.S. Patent Application Pub. No. US2005/0203712 (2005) to Lowe discloses a system in which a consumer stands on a pressure sensitive pad to produce signals concerning the shape or topography of the bottom surface of the consumer's foot. From this information a selection is made from basic orthotic shells that then can be modified to produce an orthotic.
In U.S. Patent Application Pub. No. US2006/0103852 (2006) to Klaveness a consumer places a foot on a membrane over a medium, such as a semi-transparent liquid, that is pressurized according to the consumer's weight. A scanner below the medium records light reflected from the membrane through the medium. As will be apparent, the scan is made with the consumer in a full-weight bearing position.
The Peterson published applications disclose a scanner that requires a practitioner to produce a valid image in a semi-weighted, supported position. When the air pillow is inflated, it pushes up on the plantar surface. This aligns and supports the foot structure and contains and supports foot tissue. When the foot is aligned and supported in this manner, the arch is in its anatomical position and anatomical height for the consumer. As previously indicated, measuring and scanning a foot in the full-weight or semi-weight compensated position leads to a footbed in a misaligned compensated position. Consequently, the footbed will not align and support the foot correctly.
With respect to the production-delivery phase, the prior art discloses different footbed structures. The previously identified Peterson published applications disclose a footbed that includes a bottom portion formed of a heel post stabilizer and a forefoot stabilizer. An orthotic lies on the post heel stabilizer and a portion of the forefoot stabilizer and may include a metatarsal pad and a forefoot post. A top cover then forms a laminated structure. The shipped orthotic thereby contains all the structures that are necessary to position the individual's rear foot and midfoot in a correct position.
International Publication No. WO98/52435 (1998) to McRoskey discloses adjustable orthotics comprising orthotically functional and interchangeable components. The interchangeable components are inserted into a main body after which a cover overlies the components.
U.S. Pat. No. 3,084,695 (1963) to O'Donnell discloses an arch supporting cushion inner sole. The inner sole has an intermediate sheet of sponge rubber having curved channels that define segmental areas. Selected pads are interposed between upper and lower plies whereby the pads form bulges at various areas.
U.S. Pat. No. 4,841,648 (1989) to Shaffer discloses a personalized insole kit. An insole has a surface that contains a plurality of shapes, each disposed for a specific correction. Each shape is contained on the surface of the insole by hooks and loops. The insole is marked to identify a correct location for each component. This patent specifically discloses an insole with an arch pad, a heel pad, a metatarsal pad and a corn/callous/lesion pad.
U.S. Pat. No. 5,832,634 (1998) to Wong discloses sports footwear with a sole unit that comprises at least one composite material layer partly involving the sole unit itself. Specifically the sole comprises at least one portion formed of woven composite material having a part positioned in correspondence with the metatarsal region of the user's foot and a part at a position corresponding to the arch region of the foot. The portion in the metatarsal region is flexible. The part in the plantar arch region is rigid.
The previously identified Erb et al. published application discloses footwear components selected from a plurality of pre-manufactured footwear components having substantially the same function, but having different physical attributes to accommodate different foot configurations. These include arch supports and heel pads.
In summary and as previously indicated, the Peterson published applications provide high quality orthotic footbeds. However, the costs, in time and expense, for each of the measurement and production-delivery phases are high and preclude its application to a major market. Other prior art approaches reduce the time and costs associated with some of these phases, but generally at a reduced quality, particularly in the quality of the information provided the measurement phase.
For example, the Peterson patent applications disclose measurements taken in a semi-weight bearing state. Measurement techniques that scan the feet under a full-weight bearing state can produce incorrect arch measurements. As will be apparent, arch height and length vary with weight. In a full-weight bearing state arch height is at a minimum and arch length is at a maximum. In a non-weight bearing state arch height is at a maximum and arch length is at a minimum. An intermediate and more accurate measurement occurs when the foot is in a semi-weight bearing state. Moreover, whereas the Peterson published applications disclose the use of an air cushion to capture a foot in a semi-weight bearing position; other references disclose full weight bearing with an attendant distortion on the bottom of the foot as the tissue spreads under weight.
What is needed is a system for providing method for producing footbeds for consumers in which a measurement occurs locally without the requirement for any professional assistance and yields accurate information about a consumer's feet. The system should identify an inner sole base member, an arch support and a metatarsal pad having appropriate properties based upon these measurements. The construction of a footbed should then be based upon a selected inner sole base member, arch support and metatarsal pad that is easily assembled by the consumer from an inventory at the site thereby to further minimize the cost of footbeds, even though the quality of these footbeds approaches the quality of orthotic footbeds made by either the gold standard method or by the methods in the Peterson published applications.
Therefore it is an object of this invention to provide a method and system for providing low cost, high quality footbeds to consumers.
Another object of this invention is to provide footbeds to consumers at a minimal cost.
Still another object of this invention is to provide a method and apparatus for producing footbeds in which the consumer foot measurements do not require practitioner assistance.
Yet another object of this invention is to provide a method and apparatus for producing a footbed that the consumer can assemble.
Yet still another object of this invention is to provide a method and apparatus that enables the construction of a footbed with minimal costs associated with the measurement and production-delivery phases.
Still yet another object of this invention is to provide a measurement method and apparatus that can be used by a consumer without assistance.
Still another object of this invention is to provide a production method for footbeds that is easily performed at a local site.
In accordance with one aspect of this invention a method for obtaining measurements for use in the construction of a footbed for a consumer includes the step of generating foot images of each of the consumer's feet. For each foot further measurements are made by projecting the corresponding foot image at a measurement position. A consumer places a foot on the image to enable capturing of the foot at the measurement position in a position essentially aligned with the projected foot image. An array of measurements representing the topography of the individual's foot is converted into information for producing a footbed for the individual's foot.
In accordance with another aspect of this invention, a footbed is provided for an individual's foot characterized by forefoot, rearfoot, lateral and medial column, arch and metatarsal head areas. The footbed includes an insole base, a metatarsal pad insert and an arch support insert. The insole base is taken from a group of insole bases for underlying the forefoot and rearfoot areas and portions of the lateral column area between the forefoot and rearfoot areas. The insole base has a vacuity substantially coextensive with the areas underlying the arch and metatarsal head areas and portions of the medial column area. The metatarsal pad insert is taken from a group of metatarsal pad inserts of different properties. The arch support insert is taken from a group of arch support inserts of different properties. The inserts are attached to the insole base to span the vacuity and to provide support for the metatarsal head and arch areas of the foot, respectively.
In accordance with still another aspect, this invention provides a method by which a consumer at a store can obtain a footbed with characteristics that are adapted for the consumer's feet. There is an inventory of footbed components at the store. They are organized into a plurality of groups, each with at least one subgroup. The components in each subgroup have certain characteristics. The consumer is guided through a measurement phase during which the consumer enters personal information into the system, generates a pressure map of both feet, generates a topographical map for each foot. The system then generates a list of one component from each subgroup for each foot. Thereafter the consumer gathers each component on the list from the inventory for assembly into footbeds.
The appended claims particularly point out and distinctly claim the subject matter of this invention. The various objects, advantages and novel features of this invention will be more fully apparent from a reading of the following detailed description in conjunction with the accompanying drawings in which like reference numerals refer to like parts, and in which:
The various objectives of this invention are achieved by increasing the efficiency of both the measurement phase and the production-delivery phase for providing a consumer with a set of footbeds adapted for the topography of the consumer's feet.
As shown in
Next, the consumer places a corresponding foot onto the scanner in registration with the projected foot image thereby locating the foot in a semi-weighted supported position. Process 33 then scans the foot to produce an array of measurements representing the topography of the bottom of the consumer's foot. Process 34 converts that array of measurements into a data file for further processing. Process 35 produces an output image and other information for the consumer. Processes 32 through 35 are repeated for the consumer's other foot.
Process 36 uses the information from both feet to identify components for the footbed and provides a list of those components. Process 36 represents the production-delivery phase during which the consumer obtains the identified components from the local inventory. The consumer then can easily assemble the components into footbeds that closely approximate ideal footbeds for the consumer.
As will be apparent, all the data processing occurs at the local site. As will also become evident, the consumer can be simply directed or guided through this entire operation without assistance from store personnel or practitioners. Moreover both the measurement phase and the production-delivery phase require only a few minutes to complete. As a result finished footbeds are available to the consumer quickly. The reduction in personnel requirements and the existence of a local inventory of components minimizes the costs associated with the production-delivery phase and enables such a footbed to be provided to the consumer at a reasonable cost.
The measurement phase involves interaction between the consumer and a kiosk 40 shown in
The frame 42 and housing 43 define a cavity 46 that carries a foot pillow assembly 47 based upon the pillow assembly shown in co-pending U.S. Pat. App. Pub. No. US2006/2083243. In this kiosk 40, the foot pillow assembly 47 resides on a base 50 that elevates the toe portion above the heel portion at an angle α that minimizes the consumer's physical exertion and effort in maintaining balance during a scan. Although the angle α can be in a range of about 10°≦α≦30°, in the specially disclosed implementation, α≈20°. Spaced, generally vertically extending parallel handle bars 51 attached to the frame 42 assist the consumer in maintaining balance.
Referring now to
The mirror 64 inclines downward from front to back such that the mirror 64 diverges from the transparent portion of the foot pillow assembly 47. The mirror 64 can take a number of forms, but a front surface mirror is particularly adapted for rear projection to prevent optical distortions inherent in second surface mirrors.
Still referring to
The projector 65 and camera 66 have different operating modes. In one operating mode, the camera 66 is inactive and the computer 53 causes the projector 65 to project an image of one of the consumer's feet onto the membrane 70. During the operating mode for determining the topography of the consumer's foot, the projector 65 produces, under the control of the computer 53, a series of patterns that reflect from the bottom of the consumer's foot to the non-active camera 66 acting as a frame grabber. As described more fully later, these frames are then processed to produce the list of selected footbed components.
Referring now to
The consumer's foot is considered to be in a semi-weighted support position when photodetectors associated with position detectors 72C, 72D and 72E receive light from corresponding sources and while the foot blocks light from photodetectors at the position detectors 72A and 72B. The semi-weighted support position extends over a small range of positions including the reference-neutral position defined in U.S. Pat. App. Pub. No. US2006/0283243. Consequently, information about foot topography with this system is closely analogous to that obtained with the apparatus shown in the above-identified publication.
A more thorough understanding of the operation of the system depicted in
When the consumer activates the CONTINUE icon in
Once the tactile image shown in
When the consumer actuates the START button in the screen of
When the screen in
During this time the measurements established in steps 85, 91 and 95 begin to be processed in a background mode at the signal processing step 97 as described later. When the consumer completes the entry of information in
Specifically, the screen in
As previously indicated, step 97 in
In one implementation based upon the eigenvalues of a set, the pressure data is segregated into horizontal rows to obtain the centerlines of pressure points produced while the consumer stands on the pressure mat 45 in
In an alternate implementation, step 111 performs an iterative process until convergence. In this process, a 2-component Gaussian Mixture Model (GMM) is fit to the z-coordinate data. Then only those points with z-coordinates towards the bottom of the foot are selected (e.g., those points having a threshold at maximum of the two means minus two times the corresponding standard deviation). A Principal Component Analysis (PCA) of the selected 3D points with a check of the angle between the third eigenvector (smallest eigenvalue) and the z+ vector [0;0;1]. This resulting coordinate frame is rotated using the Rodriguez formula such that the third eigenvector aligns with z+. Convergence occurs with the angle reaches a predetermined threshold or the number of iterations exceeds a predetermined value.
In either case, after the rotation value is obtained, a determination is made of the location of the plane that touches the foot from the bottom (specifically this plane is assumed to be located at mean plus two times the standard deviation of these points). With this information, the point cloud is shifted such that the bottom plane coincides with z=0.
Step 112 identifies the heel, the center of the foot and the centers of the metatarsals. Again, in one specific implementation, step 112 fits a 3-component GMM with spherical covariances to the x-y plane projection data of the point cloud (starting from initial conditions that place the component centers near the heel, in the middle, and near the metatarsal area). These points are named p1, p2 and p3, respectively.
Step 113 then determines a trapezoidal boundary for the arch region in each foot. In an implementation that is complementary to the operation of step 112, step 113 determines three line segments corresponding to boundaries of the arch region. One line segment passes through p1 in the direction of x (points with y>p1y). A second line passes through p2 in the direction of y (points with x>p1x). The third line segment passes p3 in the direction of y (points with x<p3x). The fourth side of the arch is determined using polynomial fits by partitioning the arch region into a number of equally spaced strips with respect to the x-coordinates. Then polynomials of order four are fit to the y-z data for each strip. The second derivative (quadratic) polynomial is set to zero and the root with the larger y-value is picked. Once all such roots are obtained from the strips, a median filter is applied to the y-roots and a line is fit to the x-y data (x-center of each strip and its corresponding root of polynomial). This line is the fourth boundary of the arch and typically completes a trapezoid with the other three line segments.
Next, step 114 uses a polynomial fit to the point cloud to obtain an estimate of the arch height using procedures corresponding to those described with respect to step 113, but with the various steps altered to correspond to the y axis. In this case step 114 fits a parabola to the x-z data and identifies the x-coordinate at which the parabola peaks. Next, the parabola that has the highest peak and a portion of the point cloud whose x-coordinates lie within a predetermined range that are selected to generate the highest peak and dimension of the range in the x direction. This portion of the point cloud roughly corresponds to the region of the arch where the height is maximum. A parabola fitting process applied to the y-z values of the points in this portion of the arch and an evaluation of parabola height at the outer edge of the arch provide the fourth boundary for determining arch height.
Step 115 constructs Delauney triangulation for each arch region in the point cloud and removes various triangles. With this information step 115 calculates a variety of surface area and volume features. These include various coordinates and values determined in steps 110 through 114, including arch length, area and volume values, and arch height values.
Next step 116 uses standard techniques to combine the features obtained in step 115 into summary features for arch height and arch length to produce values of true anatomical arch height and shoe size.
Step 117 then converts the information provided by step 116 into specific values for arch height and shoe size and from which component selection can be made. Specific values are represented with two corresponding and jointly Gaussian densities where the appropriate Gaussian model is selected depending on gender and parameters trained using a laser scan database. The laser scan database that has been developed from scans taken by apparatus according to U.S. Pat. Pub. No. US2006/0283243 contains appropriate information derived from thousands of scans. These joint densities yield conditional Gaussian densities corresponding to an output of the mean arch height and shoe size and a standard deviation for each. The standard deviations provide confidence intervals for mean arch height and shoe size. The conversion of this information to a list of footbed components is better understood after a discussion of the various features of a footbed structure. In addition, step 117 generates an arch length value.
As shown particularly in
The insole base 201 typically is made of foam such as ethyl-vinyl-acetate or polyurethane. Material properties of the foam may be sport specific. For example, softer and elastic foam may be selected for running, harder and viscous foam for cycling or soft and viscous foam for golf. In this particular implementation these activities are used to select either a “dynamic” or a “static” footbed insole base 201. That is, a consumer selection of walking, running or golf causes the system to select a dynamic insole base while the selection of cycling, skating and skiing causes the system to select a static insole base. Other combinations are also possible.
The final component is an arch support insert 220 shown in each of
Referring specifically to
With this range of components, it will be apparent that the materials of the insole base 201 in
As previously indicated, the system of this invention assumes that at each kiosk location there will be a matrix of components such as shown in
With this understanding of the matrix of components that may be available for a footbed, it will now be helpful to describe a process by which all the data is converted into a list of footbed components.
Step 253 uses the measured shoe size and the consumer's personal information to select specific left and right foot insole bases. For example, if the measured shoe size for the consumer's left foot is size 9 and the selected activity requires a dynamic insole base, step 253 selects a specific insole base having the specified size and the appropriate construction.
Step 254 performs a similar function. That is, the consumer's personal information and shoe size are used to identify a metatarsal pad insert of the appropriate size and the appropriate thickness.
Step 255 uses the measured shoe size and arch height to select a specific arch support insert. That is, a high, medium or low arch support insert will be identified for the selected insole base.
Step 256 uses this information to produce a ticket, for example, at a printer such as the printer 54 in
The foregoing discussion of processing is related to an independent, stand alone kiosk.
The process 35 in
In summary, there has been disclosed one implementation of a “self serve” footbed system for providing a consumer with footbeds that match his or her needs. This system includes a consumer-operated provides a measurement system, such as included in the kiosk as shown in
Such a system may perform various tests to determine at a basic level whether this system can provide satisfactory footbeds. For example, if the measurement phase determines that the required arch height exceeds the maximum height of any arch support insert, it is highly likely that the process will not produce a satisfactory footbed. Excessive rotation of the pressure image to achieve appropriate foot alignment may indicate excessive tibial torsion that could affect the validity of the measurements. If these of other tests fail, the system should display a message to the consumer terminating the process and recommending the consumer consult with a professional.
As previously indicated and referring to
This invention has been described in terms of a specific implementation with reference to specific variations. It will be obvious to those of ordinary skill in the art that myriad variations and modifications could be made to this specifically disclosed implementation without departing from the spirit and scope of this invention. Therefore, it is the intent of the appended claims to cover all such variations and modifications as come within the true spirit and scope of this invention.