Patent ID: 12221764

DETAILED DESCRIPTION

Those having ordinary skill in the art will recognize that terms such as “above,” “below,” “upward,” “downward,” “top,” “bottom,” etc., are used descriptively for the figures, and do not represent limitations on the scope of the disclosure, as defined by the appended claims. Furthermore, the teachings may be described herein in terms of functional and/or logical block components and/or various processing steps. It should be realized that such block components may be comprised of any number of hardware, software, and/or firmware components configured to perform the specified functions.

Terms of degree, such as “generally”, “substantially” or “approximately” are understood by those of ordinary skill to refer to reasonable ranges outside of a given value or orientation, for example, general tolerances or positional relationships associated with manufacturing, assembly, and use of the described embodiments.

Referring to the Figures, wherein like numerals indicate like parts throughout the several views, a surface grading system20is generally shown at20. Referring toFIG.1, the surface grading system20includes a combination of a traction unit22and a scraper implement24. The traction unit22may include and/or be referred to as a tractor, agricultural tractor, dozer, bull-dozer, vehicle, work vehicle, etc. The traction unit22may be configured in a manner that provides motive power to move the traction unit22across a ground surface26, such as but not limited to a field. While the example implementation shown in the Figures and described herein depicts the traction unit22as a conventional agricultural tractor, it should be appreciated that the teachings of this disclosure should not be limited to the implementation of the traction unit22shown and depicted herein.

The scraper implement24is attached to the traction unit22. In the example implementation shown in the Figures and described herein, the traction unit22includes a three-point hitch system28disposed at a rearward end60of the traction unit22. In other implementations, the three-point hitch system28may be positioned adjacent the forward end58of the traction unit22. Furthermore, while the example implementation includes the traction unit22having the three-point hitch system28attaching the scraper implement24thereto, it should be appreciated that in other implementations of the disclosure, the scraper implement24may be attached to the traction unit22in some other manner that is not shown or specifically described herein.

Referring toFIG.2, and as understood by those skilled in the art, the three-point hitch system28includes a first lower arm30and a second lower arm32arranged on a substantially common horizontal plane50, and an upper arm34positioned vertically above and laterally between the first lower arm30and the second lower arm32. The first lower arm30, the second lower arm32and the upper arm34each include a respective first end36, e.g., a respective forward end58, that is attached to the traction unit22, e.g., the rearward end60of the traction unit22. Each of the first lower arm30, the second lower arm32and the upper arm34extend from their respective first end36to a respective distal end38. The scraper implement24is attached to each of the first lower arm30, the second lower arm32, and the upper arm34at their respective distal end38s. One or more of the first lower arm30, the second lower arm32, and the upper arm34may be selectively controllable to move or the position and/or orientation of the scraper implement24relative to the traction unit22.

Referring toFIG.1, in the example implementation of the surface grading system20shown in the Figures and described herein, the scraper implement24is attached to the traction unit22via the three-point hitch system28. The scraper implement24may be referred to as a scraper blade, a box blade, a box scraper, a grading scraper, etc. The scraper implement24includes a cutting edge40that is configured for contacting and shaping the ground surface26. The specific type, shape, and construction of the scraper implement24other than described herein are not pertinent to the teachings of this disclosure, are understood by those skilled in the art, and are therefore not described in detail herein.

Referring toFIGS.1and2, the traction unit22includes an actuator42that is selectively controllable between a plurality of different positions. The actuator42is configured for controlling a position of the scraper implement24relative to the traction unit22. As such, a position of the cutting edge40relative to the traction unit22is adjustable in response to movement of the actuator42between the different positions of the actuator42. In the example implementation described herein, the actuator42includes a hydraulic cylinder (not shown) operable to extend or retract in response to a flow of hydraulic fluid to at least one end of the hydraulic cylinder. The actuator42may be integrated with and/or coupled to the three-point hitch system28. For example, the actuator42may be coupled to one of the first lower arm30or the second lower arm32. More particularly, in one implementation, the actuator42includes a first arm actuator44coupled to the first lower arm30and a second arm actuator46coupled to the second lower arm32. The first arm actuator44and the second arm actuator46operate in unison on the first lower arm30and the second lower arm32respectively. In the example implementation shown in the Figures and described herein, extension of the first arm actuator44and the second arm actuator46raises the scraper implement24and the cutting edge40relative to the traction unit22, whereas retraction of the first arm actuator44and the second arm actuator46lowers the scraper implement24and the cutting edge40relative to the traction unit22.

In alternative implementations, the actuator42may be embodied differently than the example implementation of the hydraulic cylinder described herein. For example, the actuator42may alternatively include an electric linear actuator42, a pneumatic linear actuator42, a rotary actuator42, an electric motor, etc. Additionally, in alternative implementations, the actuator42may be coupled to the upper arm34. It should be appreciated that the actuator42may form part are all of the first lower arm30, the second lower arm32, or the upper arm34. Furthermore, it should be appreciated that the three-point hitch system28may further include other components interconnecting the actuator42and the first lower arm, the second lower arm32, or the upper arm34, such as but not limited to, linkages, levers, gear sets, shafts, etc.

Referring toFIG.3, the surface grading system20further includes an angle sensor48. The angle sensor48is operable to sense data related to a pitch angle92of the traction unit22. The pitch angle92is defined as an angle of rotation relative to a horizontal plane50and about a transverse axis52that extends through a center of gravity54of the traction unit22. The transverse axis52is disposed on the horizontal plane50and is orthogonal to a central longitudinal axis56of the traction unit22. The central longitudinal axis56of the traction unit22extends through the center of gravity54of the traction unit22, between a forward end58and a rearward end60of the traction unit22.

The angle sensor48may include any device that is capable sensing the pitch angle92and/or data related to the pitch angle92of the traction unit22, and communicate that data to a controller62. The angle sensor48may include, but is not limited to, an accelerometer, a gyroscope, a magnetometer, etc. In one implementation, the angle sensor48includes an inertial measurement unit. It should be appreciated that the angle sensor48may include some other device capable of detecting and/or sensing data related to the pitch angle92of the traction unit22.

The surface grading system20may further include a position sensor64. The position sensor64is operable to sense data related to a geographic location of the traction unit22. The position sensor64may include, but is not limited to, a Global Positioning System (GPS) or other similar device, which uses signals from satellites to triangulate the geographic location of the traction unit22. The position sensor64is configured to continuously track the location of the traction unit22as the traction unit22moves across the ground surface26, and continuously communicate the data related to the location of the traction unit22to the controller62. It should be appreciated that the position sensor64may differ from the example implementation of the GPS sensor described herein.

The controller62is disposed in communication with the angle sensor48, the position sensor64, and the actuator42. The controller62may be configured to receive data related to the pitch angle92of the traction unit22from the angle sensor48, receive data related to the geographic location of the traction unit22from the position sensor64, and communicate a hitch control signal82to the actuator42to raise or lower the three-point hitch system28. While the controller62is generally described herein as a singular device, it should be appreciated that the controller62may include multiple devices linked together to share and/or communicate information therebetween. Furthermore, it should be appreciated that the controller62may be located on the traction unit22or the scraper implement24, or may alternatively may be located remotely from the traction unit22and the scraper implement24.

The controller62may alternatively be referred to as a computing device, a computer, a control unit, a control module, a module, etc. The controller62includes a processor66, a memory68, and all software, hardware, algorithms, connections, sensors, etc., necessary to manage and control the operation of the angle sensor48, the position sensor64, and/or the actuator42. As such, a method may be embodied as a program or algorithm operable on the controller62. It should be appreciated that the controller62may include any device capable of analyzing data from various sensors, comparing data, making decisions, and executing the required tasks.

As used herein, “controller” is intended to be used consistent with how the term is used by a person of skill in the art, and refers to a computing component with processing, memory, and communication capabilities, which is utilized to execute instructions (i.e., stored on the memory68or received via the communication capabilities) to control or communicate with one or more other components. In certain embodiments, the controller62may be configured to receive input signals in various formats (e.g., hydraulic signals, voltage signals, current signals, CAN messages, optical signals, radio signals), and to output command or communication signals in various formats (e.g., hydraulic signals, voltage signals, current signals, CAN messages, optical signals, radio signals).

The controller62may be in communication with other components on the traction unit22and/or the scraper implement24, such as hydraulic components, electrical components, and operator inputs within an operator station of the traction unit22. The controller62may be electrically connected to these other components by a wiring harness such that messages, commands, and electrical power may be transmitted between the controller62and the other components. Although the controller62is referenced in the singular, in alternative embodiments the configuration and functionality described herein can be split across multiple devices using techniques known to a person of ordinary skill in the art.

The controller62may be embodied as one or multiple digital computers or host machines each having one or more processor, read only memory (ROM), random access memory (RAM), electrically-programmable read only memory (EPROM), optical drives, magnetic drives, etc., a high-speed clock, analog-to-digital (A/D) circuitry, digital-to-analog (D/A) circuitry, and any required input/output (I/O) circuitry, I/O devices, and communication interfaces, as well as signal conditioning and buffer electronics.

The computer-readable memory68may include any non-transitory/tangible medium which participates in providing data or computer-readable instructions. The memory68may be non-volatile or volatile. Non-volatile media may include, for example, optical or magnetic disks and other persistent memory. Example volatile media may include dynamic random access memory (DRAM), which may constitute a main memory. Other examples of embodiments for the memory include a floppy, flexible disk, or hard disk, magnetic tape or other magnetic medium, a CD-ROM, DVD, and/or any other optical medium, as well as other possible memory devices such as flash memory.

The controller62includes an Artificial neural network (ANN)70. An example implementation of the ANN70is schematically shown inFIG.4. As is understood by those skilled in the art, the ANN70includes a plurality of connected nodes or neurons, often referred to as artificial neurons72. Each connection between artificial neurons72may transmit a signal therebetween. An artificial neuron72may process a signal received as an input or from one artificial neuron72, and may communicate a signal to other artificial neurons72connected to it. The “signal” is a real number, and the output of each artificial neuron72is computed by a function of the sum of its inputs. The inputs and the connections between connected artificial neurons72typically have a weight W that adjusts as learning proceeds. The weight W increases or decreases the strength of the input or the signal to the artificial neurons72. Additionally, each artificial neuron72may include a bias b, which is a constant that is added to the sum of the inputs and/or received signals of the respective artificial neuron72. Typically, artificial neurons72are aggregated into layers. Different layers may perform different transformations or functions on their respective inputs and/or received signals. Signals travel from a first layer74(the input layer), to a last layer (an output layer76), possibly after traversing the layers multiple times. The ANN70is trained and/or learns the parameters required to level the ground surface26by being exposed to a set of training data as is understood in the art. The trained ANN70automates height control of the cutting edge40of the scraper implement24to improve the user comfort and quality of work.

In the example implementation of the ANN70shown inFIG.4and described herein, the ANN70receives at least a first input78and a second input80, and includes the first layer74and the output layer76. In the example implementation described herein, the first input78is defined as the pitch angle92, and the second input80is defined as a leveling variation94. The pitch angle92and the leveling variation94are the input values of the first layer74. It should be appreciated that the ANN70may include other inputs not specifically described herein, such as but not limited to, an engine load, an engine speed, an engine temperature, a transmission speed, a transmission torque, a transmission temperature, etc. The first layer74of the ANN70may include any number of artificial neurons72, i.e., 1, 2, 3, . . . n, with each artificial neuron72of the first layer74including a respective function weight W for each of the inputs, e.g., the pitch angle92and the leveling variation94, and a respective neuron bias b, as is understood by those skilled in the art. The hitch control signal82is the output value of the output layer76. In the example implementation described herein, the output layer76includes a single artificial neuron72, having a respective weight W for each result received from each of the artificial neurons72of the first layer74, and a respective neuron bias b, as is understood by those skilled in the art. The hitch control signal82is configured to control a position of the actuator42, thereby controlling a position of the three-point hitch system28relative to the traction unit22. More particularly, the hitch control signal82may be a signal to raise or lower the three-point hitch system28. The hitch control signal82may include, but is not limited to, an electric signal, an electro-hydraulic signal, a pneumatic signal, etc.

As described above, each layer of the ANN70may perform a respective function on its respective input values. In the example implementation described herein, the first layer74uses a logarithmic sigmoid function (logsig)

F1⁡(s)=11+e-s

as an activation function of the first layer74. It should be appreciated that the activation function of the first layer74may differ from the logarithmic sigmoid function described in the example implementation. In the example implementation described herein, the second or output layer76uses a linear function (purelin) F2(s)=s, as an activation function of the output layer76. It should be appreciated that the activation function of the output layer76may differ from the linear function described in the example implementation.

As described above, the controller62includes the tangible, non-transitory memory68on which are recorded computer-executable instructions. The instructions may include a grading control algorithm84. The processor66of the controller62is configured for executing the grading control algorithm84. The grading control algorithm84implements a method of grading the ground surface26with the surface grading system20, described in detail below.

Referring toFIG.6, the method of grading the ground surface26with the surface grading system20includes receiving a desired elevation86of the ground surface26. The step of receiving the desired elevation86of the ground surface26is generally indicated by box inFIG.6. The desired elevation86of the ground surface26may be input into the controller62by an operator via a user interface88. The user interface88may include, but is not limited to, a touch screen display, a keyboard, a microphone, a data file, etc. The desired elevation86of the ground surface26may include, but is not limited to, a single geo-referenced elevation establishing a horizontal surface, a plurality of geo-referenced elevations establishing an inclined plane, or a plurality of geo-reference elevations establishing a three-dimensional surface The desired elevation86of the ground surface26may be input as, but is not limited to, an elevation associated with an established datum, or as an elevation associated with defined reference, mark, or indicator. The indicator may include for example, but is not limited to a laser level or reference marker.

A current location of the traction unit22, and/or data related to the current location of the traction unit22, may be sensed with the position sensor64. The current location of the traction unit22may be associated with a specific location or reference point100relative to a component of the traction unit22, such as but not limited to, a specific location on or relative to the position sensor64. The step of sensing the current location of the traction unit22is generally indicated by box122inFIG.6. The data related to the current location of the traction unit22and/or the current location of the traction unit22may then be communicated to the controller62, with the controller62receiving the data related to the current location of the traction unit22from the position sensor64. As described above, the position sensor64may include, but is not limited to, the GPS sensor. The current location of the traction unit22may be sensed continuously as the traction unit22moves across the ground surface26, or may be sensed at discrete intervals as the traction unit22moves across the ground surface26such that the movement of the traction unit22across the ground surface26may be tracked.

The pitch angle92of the traction unit22at the current location and/or data related to the pitch angle92of the traction unit22at the current location of the traction unit22is also sensed with the angle sensor48. The step of sensing the pitch angle92of the traction unit22is generally indicated by box124inFIG.6. The pitch angle92and/or the data related to the pitch angle92of the traction unit22, may then be communicated to the controller62, with the controller62receiving the data related to the pitch angle92of the traction unit22at the current location of the traction unit22from the pitch sensor. The angle sensor48may sense and/or determine the pitch angle92, or may sense the data that is communicated to the controller62, which in turn calculates or otherwise determines the pitch angle92of the traction unit22at the current location from the data. The pitch angle92of the traction unit22at the current location may be sensed continuously as the traction unit22moves across the ground surface26, or may be sensed at discrete intervals as the traction unit22moves across the ground surface26such that pitch angle92of the traction unit22may be tracked as the traction unit22moves across the field.

The controller62may calculate a current location of the cutting edge40of the scraper implement24using the current location of the traction unit22, the pitch angle92of the traction unit22at the current location of the traction unit22, and an identifiable dimension90A,90B of the traction unit22or the scraper implement24. The step of calculating the current location of the cutting edge40is generally indicated by box126shown inFIG.6. Calculating the current location of the cutting edge40of the scraper implement24includes calculating the elevation of the cutting edge40of the scraper element. As such, the current location of the cutting edge40of the scraper implement24includes a geo-referenced location, including a latitude component, a longitude component, and an elevation component of the cutting edge40relative to the ground surface26. Accordingly, the cutting edge40of the scraper implement24is located relative to the ground surface26.

As described above, the controller62may calculate or otherwise determine the current location of the cutting edge40using the current location of the traction unit22, the pitch angle92of the traction unit22, and an identifiable dimension90A,90B of the traction unit22or the scraper unit. The identifiable dimension90A,90B may include one or more dimensions of the traction unit22and/or the scraper implement24. For example, the identifiable dimension90A,90B may include, but is not limited to, a length of the traction unit22, a wheelbase of the traction unit22, a length of the scraper implement24, a distance along a longitudinal axis of the traction unit22between a front tire contact position and a rotation point of the three-point hitch system28, a distance from the rotation point of the three-point hitch system28and the cutting edge40, a distance between the rotation point of the three-point hitch system28and the reference location of the position sensor64, etc. Using the above identified criteria, the controller62may calculate the current location of the cutting edge40using known mathematical relationships/equations.

Once the location of the cutting edge40of the scraper implement24has been calculated or otherwise determined, the controller62may then calculate the leveling variation94. The step of calculating the leveling variation94is generally indicated by box128shown inFIG.6. The leveling variation94is a numerical difference between the current elevation of the cutting edge40of the scraper implement24and the desired elevation86of the ground surface26at the current location of the cutting edge40of the scraper implement24.

The controller62may generate the hitch control signal82based on the pitch angle92of the traction unit22at the current location of the traction unit22and the leveling variation94. The step of generating the hitch control signal82is generally indicated by box130shown inFIG.6. As described above, the hitch control signal82is operable to control the three-point hitch system28to adjust a vertical position of the cutting edge40of the scraper implement24relative to the traction unit22. The hitch control signal82may be continuously generated as the traction unit22moves across the ground surface26, or may be generated at discrete intervals as the traction unit22moves across the ground surface26. By so doing, the position of the cutting edge40of the scraper implement24is continuously adjusted as the traction unit22moves across the ground surface26to level the ground surface26and achieve the desired elevation86of the ground surface26.

As described above, the hitch control signal82may include a signal to selectively control the actuator42in order to raise or lower the three-point hitch system28, thereby changing the position of the cutting edge40of the scraper implement24relative to the traction unit22. Notably, the elevation of the cutting edge40of the scraper implement24relative to the ground surface26may not change with movement of the actuator42, but the relative position of the cutting edge40relative to the traction unit22may change in order to maintain the elevation of the cutting edge40relative to the ground surface26.

In the example implementation described herein, the controller62generates the hitch control signal82using the ANN70. As described above, the ANN70uses the pitch angle92and the leveling variation94as the inputs into the first layer74of artificial neurons72. Each artificial neuron72of the first layer74uses the activation function of the first layer74, e.g., the logarithmic sigmoid function described above, to perform a mathematical operation of the inputs, and passes the result onto the artificial neurons72of the subsequent layer, e.g., the output layer76described above. Each artificial neuron72of the output layer76uses the activation function of the output layer76, e.g., the liner function described above, to perform a mathematical operation on the results received from the artificial neurons72of the first layer74, and generates an output of the ANN70. The output of the ANN70is the hitch control signal82. It should be appreciated that the ANN70may be constructed differently than the example implementation described herein, and may include a different number of layers, different numbers of artificial neurons72in each layer, and/or use different activation functions at each layer than those described herein.

The controller62may then apply the hitch control signal82to the actuator42of the three-point hitch system28. The step of applying the hitch control signal82to the actuator42is generally indicated by box132shown inFIG.6. The hitch control signal82is applied to the actuator42in order to adjust the vertical position of the cutting edge40of the scraper implement24relative to the traction unit22. As described above, the hitch control signal82may be a signal or command to raise or lower the three-point hitch system28. As such, once the hitch control signal82is applied to the actuator42, the actuator42moves in response to the hitch control signal82, e.g., extending or retracting, whereby the vertical position of the cutting edge40of the scraper implement24relative to the traction unit22is altered.

The controller62continuously generates the hitch control signal82to continuously adjust the vertical position of the cutting edge40of the scraper implement24as the traction unit22moves across the ground surface26. As such, as the current position of the traction unit22and the pitch angle92of the traction unit22changes, the controller62calculates the leveling variation94and generates the hitch control signal82. This continuous process enables the controller62to automatically grade the ground surface26to the desired elevation86of the ground surface26. The above described surface grading system20and method of grading the ground surface26reduces the skill level required by the operator to achieve the desired elevation86of the ground surface26, and may reduce the time and cost of grading the ground surface26to the desired elevation86when compared to a non-automated grading system.

Referring toFIGS.3and5, calculation of current location of the cutting edge40, including the elevation of the cutting edge40, as well as the leveling variation94, are further explained. Point100represents the reference location of the position sensor64, point104represents the location of the cutting edge40of the scraper implement24, and a point106represents a point of rotation relative to the traction unit22of the three-point hitch system28. In the example implementation, the current location of the traction unit22is associated with point100. It should be appreciated that the calculation of the current location of the cutting edge40may differ from the example implementation, and is dependent upon the specific portion of the traction unit associated with the current location100of the traction unit22. In other words, if the current location100of the traction unit22is associated with a location of the traction unit22other than the reference location100of the position sensor64described herein, then the mathematical calculations of the current location of the cutting edge40may differ from the example implementation described herein.

As shown inFIGS.3and5, a length or distance between the reference location100of the position sensor64and the point106representing the point of rotation of the three-point hitch system28relative to the traction unit22may be defined as an identifiable dimension90A, and may be measured and/or otherwise known. A length or distance between the point106representing the point of rotation of the three-point hitch system28relative to the traction unit22and the cutting edge40may be defined as an identifiable dimension90B and may be measured and/or otherwise known. The location of point104relative to point100may be derived from the relative position of point100, the pitch angle92, an angle96, and an angle102. The pitch angle92is represented as δ in the equations below. The angle96is an angle formed between a line segment passing through the reference point106and parallel with the central longitudinal axis56, and a vector representing identifiable dimension90B. The angle96is represented asp in the equations below. The angle102is an angle formed between a line segment passing through the reference point100and normal to the central longitudinal axis56, and a vector representing identifiable dimension90A. The angle102is represented as δ in the equations below.

The position of reference point100, e.g., the current location of the traction unit22, is defined in the equations below as A=[Ax,Ay]. The scraper implement24is pivoted relative to the traction unit22at point106, which represents the fixed point in the three-point hitch system28that moves the cutting edge40, i.e., point104, relative to the traction unit22. The location of point106is defined in the equations below as B=[Bx,By]. The location of point106may be derived from equation (1) below using the location of the reference point100, defined as A=[Ax,Ay], the identifiable dimension90A, the pitch angle92, and the angle102.

B⁡[Bx,By]=[(Ax-90⁢A×sin⁡(δ-θ)),(Ay-90⁢A×cos⁡(δ-θ))](1)

Referring toFIGS.3and5, the variable position of the cutting edge40of the scraper implement24is represented by point104. Knowing the relative position of point100, which may be determined from the position sensor64for example, the location of point104of the cutting edge40may be calculated. The location of point104is defined in the equations below as C′=[Cx′, Cy′]. The location of point104is affected by the pitch angle92of the traction unit22, represented in the equations by angle δ, and by the angle96represented in the equations by β. Angle96is controlled and/or adjusted by the hitch control signal82. In the example implementation described herein, the hitch control signal82is generated by the ANN70. The location of point104of the cutting edge40of the scraper implement24is represented as C′=[Cx′,Cy′] in equation (2), shown below.

C′⁡[Cx′,Cy′]=[(Bx-(90⁢B×cos⁡(θ+β))),(By-(90⁢B×sin⁡(θ+β)))](2)

The ground leveling variation94is derived from comparing the y component of point104, i.e., as Cy′ with the y component Ryof the desired elevation86of the ground surface26at the current location of the cutting edge40of the scraper implement24. The leveling variation94may be calculated from equation (3) below.

Leveling⁢⁢Variation=Cy′-Ry(3)

As used herein, “e.g.” is utilized to non-exhaustively list examples, and carries the same meaning as alternative illustrative phrases such as “including,” “including, but not limited to,” and “including without limitation.” As used herein, unless otherwise limited or modified, lists with elements that are separated by conjunctive terms (e.g., “and”) and that are also preceded by the phrase “one or more of,” “at least one of,” “at least,” or a like phrase, indicate configurations or arrangements that potentially include individual elements of the list, or any combination thereof. For example, “at least one of A, B, and C” and “one or more of A, B, and C” each indicate the possibility of only A, only B, only C, or any combination of two or more of A, B, and C (A and B; A and C; B and C; or A, B, and C). As used herein, the singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. Further, “comprises,” “includes,” and like phrases are intended to specify the presence of stated features, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, steps, operations, elements, components, and/or groups thereof.

The detailed description and the drawings or figures are supportive and descriptive of the disclosure, but the scope of the disclosure is defined solely by the claims. While some of the best modes and other embodiments for carrying out the claimed teachings have been described in detail, various alternative designs and embodiments exist for practicing the disclosure defined in the appended claims.