Pitch-based control for sprayers and sprayer operations

A computer-implemented method and a control system are described for controlling one or more operations of a sprayer vehicle with a tilt-detection mechanism, a tank, and a tank fill-volume sensor. The tilt-detection mechanism is utilized to determine a tilt indicator. A tilt value is determined based upon the tilt indicator. A tank fill-volume indicator is determined based upon information from the tank fill-volume sensor. A tilt-corrected fill-volume of the tank is determined based upon the tilt value and the tank fill-volume indicator.

CROSS-REFERENCE TO RELATED APPLICATION(S)

Not applicable.

STATEMENT OF FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not applicable.

FIELD OF THE DISCLOSURE

This disclosure relates to control of spraying operations in a sprayer vehicle, including tank filling, tank mixing, spray application, and other operations.

BACKGROUND OF THE DISCLOSURE

In various settings, it may be useful to provide a sprayer vehicle for spraying various liquids and liquid solutions over agricultural (or other) areas. Typical sprayer vehicles may include one or more tanks, which may be filled with various substances, as well as various spraying devices for dispersing the contents of the tank(s) during a spray application.

In various operations, it may be useful to determine the volume of a substance in a tank (i.e., the tank “fill-volume”) with a relatively high precision. For example, certain spraying operations may utilize mixtures of relatively precise composition, which must be pre-mixed within the sprayer tank by adding various chemicals (e.g., various powdered chemicals) to one or more carrier liquids (e.g., water). Accordingly, in order to ensure appropriate mixture composition, it may be useful to know the fill-volume of a carrier with relatively high accuracy. Similarly, knowledge of precise tank fill-volumes may ensure that sufficient liquid (or other substance) is provided to cover the entire area to be sprayed, as well as allowing more accurate tracking of chemical dispersal over a field. To this end, various devices may be provided to measure an indicator of substance volume. For example, sight tubes may be provided on sprayer tanks in order to allow an operator to visually assess fill-volume. Likewise, devices such as load cells or float sensors may provide more automated measurements of tank fill-volumes.

In various instances, however, a sprayer vehicle may be oriented with various degrees of tilt. For example, if a vehicle stops on contoured or slanted terrain for a filling or mixing operation, or drives over contoured or slanted terrain for a spraying operation, the vehicle may experience various degrees of pitch or roll. As used herein, the “pitch” of a vehicle may refer to a rotation of the vehicle about an axis extending along a lateral fore-aft centerline of the vehicle, as would correspond to inclination or declination of the vehicle in the forward and reverse directions of travel, or the fore and aft of the vehicle when stationary. The “roll” of a vehicle, in contrast, may correspond to side-to-side vehicle rotation about a longitudinal centerline of the vehicle. It will be understood that tilt may adversely affect the accuracy of known devices for measuring fill-volume, potentially resulting in sub-optimal accuracy in fill-volume assessments.

SUMMARY OF THE DISCLOSURE

A control system and computer-implemented method are disclosed for controlling aspects of sprayer operations, including tank filling, mixing of different liquids or other substances, and spray-application operations.

According to one aspect of the disclosure, a computer-implemented method is applied with respect to a sprayer vehicle with a tilt-detection mechanism, a tank, and a tank fill-volume sensor. The tilt-detection mechanism is utilized to determine a tilt indicator and at least one tilt value is determined based upon the tilt indicator. A tank fill-volume indicator is determined based upon information from the tank fill-volume sensor. A tilt-corrected fill-volume of the tank is determined based upon the tilt value and the tank fill-volume indicator.

In certain embodiments, the at least one tilt value includes a pitch value and a roll value. A roll- or pitch-corrected fill-volume estimate may be determined based upon the tank fill-volume indicator and, respectively, the roll or pitch value. A pitch- or roll-based fill-volume correction may be determined based upon the tank fill-volume indicator and, respectively, the pitch or roll value. The tilt-corrected fill-volume may then be determined based upon subtracting the pitch- or roll-based correction from, respectively, the roll- or pitch-corrected estimate.

In certain embodiments, the tank may receive a primary substance during a primary fill operation and the tilt-corrected fill-volume is determined to represent, at least in part, an amount of primary substance in the tank. An indicator of the tilt-corrected fill-volume is provided after the primary fill operation and an amount of secondary substance is received, in a secondary fill operation, with the amount of secondary substance being determined based upon the tilt-corrected fill-volume indicator.

In certain embodiments, an indicator of the tilt-corrected fill-volume may be provided to a material-management system to manage one or more aspects of at least one of a tank-filling, a tank-mixing, and a spray application. A pumping operation for filling the tank may be controlled based upon the tilt-corrected fill-volume.

According to another aspect of the disclosure, a control system includes one or more processor devices and one or more memory architectures coupled with the one or more processor devices. The one or more processor devices may be configured to execute various aspects of the method summarized above, as well as various other functionality.

The details of one or more implementations of the disclosure are set forth in the accompanying drawings and the description below. Other features and advantages will become apparent from the description, the drawings, and the claims.

DETAILED DESCRIPTION

The following describes one or more example implementations of the disclosed system and method, as shown in the accompanying figures of the drawings described briefly above.

As noted above, it may be useful to determine the volume of liquid (or other substance) in a sprayer tank with relatively high precision. For example, if a sprayer tank is to be filled with a carrier liquid (e.g., water), and a secondary substance (e.g., pesticide, herbicide, or fertilizer) is to be diluted to a particular concentration in the carrier liquid, it may be useful to know the volume of carrier liquid in the tank with relatively high precision in order to determine the appropriate volume (or weight) of secondary substance to be added. Similarly, in cases where a material (or other) management system is to be used to track the application of a substance (e.g., an herbicide mixture) at various field locations (or to track other aspects of sprayer operation), it may be useful to provide to such a system a relatively precise measure of how much of the substance is present in a sprayer tank at various times. (Various examples discussed herein may address liquid levels in a sprayer tank. It will be understood, however, that the principles disclosed herein may also be applied in tanks for non-liquid substances.)

As also noted above, determination of the volume of substance in a tank (i.e., tank “fill-volume”) may be complicated by operation of a vehicle (e.g., a sprayer vehicle) on non-level terrain. (It will be understood that “operation” as used herein, may include use of a vehicle in stationary applications, such as in a tank-filling or tank-mixing operation.) This may result, for example, because various degrees of tilt of a vehicle may result in tilting of the vehicle's tank. If a sensor or other device directed toward the volume of substance within a tank (e.g., a level sensor within the tank, a load sensor, a sight tube, and so on) has been calibrated for level operation, this tilting may result in relatively reduced accuracy for substance volumes that are determined from such a sensor or device. For example, if a float sensor is provided for measuring liquid height within a sprayer tank, and the tank is tilted away from its normal orientation, the level (i.e., height) of liquid measured by the float sensor may not accurately map to the actual liquid volume within the tank. This may be particularly true at higher degrees of tilt, and in tanks with complex geometry (e.g., because liquid may tend to pool in various internal cavities of the tank). In order to address this and other issues, a pitch-based sprayer control (“PBSC”) method or similar control system, is disclosed herein.

In certain embodiments, under a PBSC method, a model (e.g., a numerical model) or look-up table relating tank volume to a separate, measured quantity may be determined. For example, for a tank employing a float-style (or other) level sensor, numerical (or other) modeling of the tank may allow the determination of a polynomial (or other) relationship between the sensed fill level of a tank (e.g., the height of liquid in the tank as measured by the level sensor), the tilt of the tank (e.g., pitch and roll, which may generally correspond to the pitch and roll of the associated vehicle), and actual fill-volume of the tank (e.g., actual liquid volume within the tank). In level operation, the level sensor may provide a relatively accurate indicator of liquid volume within the tank (e.g., through an appropriately correlated relationship between liquid level sensed by the sensor, and the actual fill-volume). During non-level operation, however, tilt of the tank (e.g., by virtue of similar tilt of the sprayer vehicle) may cause liquid to over-fill various portions of the tank, which may detrimentally affect the correlation between the level sensed by the level sensor and the actual volume of liquid in the tank. A PBSC method may utilize the above-noted numerical (or other) model to correct the liquid volume accordingly. For example, an on-board (or other) controller for the associated sprayer vehicle may receive a measurement (or other indicator) of vehicle tilt, as well as a reading from the level sensor. The controller may then input these values into the numerical (or other) tank model (or use the values to reference an appropriate look-up table) in order to determine a tilt-corrected volume of the liquid in the tank.

The tilt-corrected volume, as determined by a PBSC method, may then inform various sprayer operations. For example, the tilt-corrected volume may guide a filling operation, allowing a tank to be filled to a relatively precise level even on uneven terrain. Similarly, the tilt-corrected volume may guide a mixing operation. For example, if a tank has been filled with a primary substance (e.g., a carrier liquid such as water), the tilt-corrected volume of the primary substance may be utilized to guide addition (and mixing) of a secondary substance that is to be diluted therein (e.g., a powdered or liquid pesticide, herbicide, or fertilizer). Further, a tilt-corrected volume may be provided to various material-management systems to allow for detailed and accurate tracking of material usage, dispersal locations, and so on.

It will be understood that sensors of other types may be employed for a particular sprayer as an alternative (or in addition) to the level sensor noted in the example above. As such, one or more other sensor types that measure values relating to tank fill-volumes may be utilized to determine one or more inputs to a PBSC method. For example, certain sprayers may be equipped with load sensors at various locations beneath the sprayers' tanks. As with level sensors, such load sensors may provide lower-accuracy assessment of liquid levels when the relevant sprayers are operating on tilted terrain. For example, if vehicle tilt causes liquid within a tank to pool in a location removed from the associated load sensor(s), the sensor(s) may indicate a lower-than-actual load of liquid for the tank, which may result in calculation of a lower-than-actual liquid volume for the tank. As with a level sensor, however, measurements from such a load sensor may be utilized in a PBSC method in order to determine a corrected assessment of liquid (or other fill) volume for the tank.

Referring now toFIG. 1, a PBSC method may be implemented with respect to a variety of vehicles, including example sprayer10. Sprayer10(or other sprayers) may include one or more primary tanks, such as tank12, for storage, mixing, and dispersal of various substances (e.g., various liquids). Sprayer10may also include one or more secondary tanks, such as tank14, which may store one or more additional substances to be added to tank12as desired or otherwise mixed with the substance in tank12for a spraying operation. Tanks12and14may be designed in various known ways and from various known materials, including stainless steel or other metals, or various polymer materials.

Sprayer10may include various screens or other display devices. For example, display16(shown removed from protective panel16a), or another output interface, may provide an active display to indicate a current fill-volume of tank12at various times. Similar displays and other output interfaces (not shown) may also be provided, including within the cab of sprayer10. Display16, which may be an LCD or other device, may be in communication with controller20(which may include various processors, memory architectures, programmable electronic circuits, and so on), or with various other computing devices and systems (e.g., a CAN bus of sprayer10) (not shown).

Sprayer10may also include tilt sensor18, which may be configured to determine the pitch and roll of sprayer10(or an indicator thereof) and provide a signal representing that pitch and roll (or the indicator thereof) to controller20or another computing device (e.g., via a CAN bus (not shown) of sprayer10). In certain embodiments, tilt sensor18may measure various indicators of tilt, rather than measuring tilt directly. For example, tilt sensor18may include one or more accelerometers, which may measure various acceleration values, or may include various other devices for measuring various other tilt-related values. Tilt sensor18may then utilize these indicator values itself in order to determine an actual tilt of the sprayer, or may transmit them to another computing device, such as controller20, for a similar operation.

In certain embodiments, tilt sensor18may include a multi-axis (e.g., three-axis) accelerometer, in which case a pitch value for sprayer10may sometimes be determined directly from the accelerometer measurements. For example, certain GPS devices included in various vehicles (e.g., various tractors) may include various accelerometers (e.g., one or more tri-axial accelerometers) which may be utilized as part of determining a vehicle pitch. Other devices may also be utilized, including in various combinations. For example, certain embodiments may utilize gyroscopes, fluid-based devices (including fluid-based accelerometers), or other measurement devices to determine vehicle tilt, or tilt indicators.

In certain implementations, accelerometer measurements from tilt sensor18may be combined with other information in order to determine a tilt value for sprayer10(i.e., tilt sensor18may determine various tilt-related values, which may be utilized in combination with other values, or by other devices, to derive the actual vehicle tilt). For example, in certain implementations, a forward/reverse acceleration value for sprayer10may be determined based upon determining a wheel speed of the sprayer, then computing a derivative of the determined wheel speed (i.e., the wheel-based acceleration). Assuming little or no wheel slippage (or taking into account the degree of wheel slippage), this acceleration may then be appropriately subtracted from an acceleration value determined based upon accelerometer measurement (e.g., from tilt sensor18), in order to remove from the determined acceleration value the acceleration resulting from actual forward/reverse vehicle acceleration. The remaining acceleration value, accordingly, may be utilized (along with the known acceleration of gravity) to determine an appropriate tilt value for the vehicle.

It will be understood, that sprayer10may undergo significant amounts of tilt (e.g., 15 degrees or more) during certain operations (including stationary operations). Accordingly, it will be understood that tilt sensor18may be selected in order to provide relatively high accuracy tilt measurement over a wide range of potential tilt values.

In certain embodiments, one or more float (or other) sensors may be utilized within tank12in order to provide a measurement of liquid levels within the tank. For example, referring also toFIGS. 2A and 2B, generally rounded stainless steel tank12aor complex polymer tank12bmay be utilized on sprayer10. Tanks12aand12bmay include, respectively, level sensors30aand30b(shown removed from tanks12aand12b, for clarity of presentation). Sensors30aand30b(or other tank sensors) may be generally centered within their respective tanks, or may be oriented in other locations. In either of sensors30aand30b, a float (e.g., float32aor32b) may ride along a vertical (or other) guide (e.g., guide34aor34b), with sensors30aand30bproviding an output voltage (or other signal) depending on the position of float30aor30bon guide34aor34b. In this way, for example, sensors30aand30bmay provide a signal to controller20(or another computing device), which may indicate the respective measured level of liquid within tanks12aand12b.

Sensors30aand30bmay be generally calibrated with respect to level operation of sprayer12, such that the level-indicating output signal (e.g., the voltage) provided by the sensors may be directly converted to a fill-volume for the associated tank. However, if tanks12aand12bare subjected to tilt (e.g., to varying degrees of pitch or roll), the liquid level indicated by the position of floats32aand32bmay no longer correspond to a liquid level that is indicative of the actual fill-volume of tanks12aand12b. Accordingly, unless appropriate correction is applied, the signal provided by sensors30aand30bto controller30may correlate to a fill-volume that does not accurately represent the amount of liquid within tanks12aand12b. In certain implementations, and at expected degrees of tilt, this error may amount to 50 gallons or more (e.g., for a 1200 gallon tank), which could lead to significant inaccuracies in mixing (or other) operations.

Accordingly, and referring also toFIG. 3, a PBSC method, such as method200, may be applied. In certain embodiments, method200may be applied for a sprayer vehicle including a tilt-detection mechanism (e.g., tilt sensor18), a tank (e.g., tank12), and a tank sensor (e.g., float sensor30a).

In certain embodiments, instruction sets and subroutines representing a PBSC method (e.g., PBSC method200) may be stored on storage device forming part of (or otherwise coupled to) controller20, and may be executed by one or more processors and one or more memory architectures (e.g., as included in or associated with controller20). In certain implementations, a PBSC method (e.g., PBSC method200) may be a stand-alone method. In certain implementations, a PBSC method may operate as part of, or in conjunction with, one or more other methods or processes and/or may include one or more other methods or processes. Likewise, in certain implementations, a PBSC method may be represented and implemented by an entirely hardware-based configuration, in addition or as an alternative to a configuration having a PBSC method as a set of instructions stored in a storage device (e.g., a storage device included in or associated with controller20). For the following discussion, PBSC method200will be described for illustrative purposes. It will be understood, however, that other configurations may be possible.

With respect to sprayer10, with which PBSC method200may be associated (and within which it may be stored or executed), PBSC method200may include determining202an indicator of a tilt of sprayer10and determining210a tilt value based upon the determined202tilt indicator. In certain embodiments, PBSC method200may include determining202an indicator of a degree of pitch204or roll206of sprayer10by way of tilt sensor18. For example, tilt sensor18may detect a degree of acceleration of sprayer10(e.g., as discussed in greater detail above), which may then be converted to an indicator of vehicle pitch204and roll206in order to assist in determining210the tilt value. In certain implementations, the tilt sensor18may then provide232the determined202tilt indicator to a computing device (e.g., the controller20). (In this and other aspects, information may be communicated between various components of the sprayer10(and other platforms) through wired connections, through wireless transmissions, or otherwise.)

Other means of determining210the tilt value may also be employed. Further, in certain embodiments, a tilt-detection mechanism (e.g., tilt sensor18) may determine210a tilt value with or without the assistance of a separate computing device. For example, tilt sensor18may determine202voltage signals representing various degrees of acceleration of sprayer10and may itself determine210a tilt of sprayer10based upon those signals (e.g., with an included computing device, such as a processor and memory architecture, a programmable electronic circuit, and so on). (Likewise, various devices not limited to sensor18and controller20may work independently, in conjunction, or otherwise, with respect to this or various other aspects of method200).

Method200may further include determining212a tank fill-volume indicator based upon information from fill-volume sensor208. The fill-volume sensor208may determine234fill volume information in a variety of ways. In certain implementations, for example, fill-volume sensor208may not necessarily measure the actual fill-volume of liquid (or other substance) in tank12, but may detect a related value such as liquid height within the tank, local liquid weight, local liquid pressure, and so on. In certain implementations, this determined234information may be provided236to a computing device (e.g., a computing device included in the sensor208or a separate controller or other device), which may then determine212a tank fill-volume indicator. In certain implementations, the fill-volume sensor208(e.g., via an included computing device) may itself determine212a fill-volume indicator, then provide236this indicator to another device.

In an example operation, a level sensor for tank12(e.g., a float sensor, such as float sensor30a) may provide fill-volume information in the form of a voltage indicator that correlates to the height of liquid within tank12, as sensed by the level sensor. After appropriate calibration of such a level sensor (or other sensor208), and during level (i.e., non-tilted) operation of sprayer10, the output of the sensor (e.g., the output voltage) may then be converted to an estimate of the current fill-volume of liquid (or other substance) within the relevant tank. In non-level operations, however, this conversion may not provide an appropriately accurate fill-volume. As such, method200may include determining214a tilt-corrected fill-volume based upon both the determined212fill-volume indicator and the determined210tilt value. For example, a polynomial (or other) model or related look-up table may be employed to utilize one or more determined210tilt values (e.g., vehicle pitch204and roll206) in conjunction with the determined212fill-volume indicator, in order to determine214a tilt-corrected fill-volume. In certain implementations, an indicator of the determined214tilt-corrected fill-volume may then be provided238at an output interface (e.g., an output interface of the relevant computing device or a display device such as display16).

Continuing, in certain embodiments, vehicle pitch204and vehicle roll206(e.g., as determined210based upon the determined202indicator of vehicle tilt) may be utilized separately in order to determine214a tilt-corrected fill volume. For example, a first numerical model (or look-up table) for the relevant tank, which may relate tank fill-volume to tank pitch (e.g., determined to be equal to vehicle pitch204) and the determined212fill-volume indicator (e.g., a voltage indicating a height of a float sensor). Accordingly, this first model (or table) may be used to determine216a preliminary pitch-corrected estimate based upon the determined210vehicle pitch204and the determined212tank fill-volume indicator. Further, a second numerical model may represent the fill-volume error introduced by the determined210vehicle roll206(e.g., determined to be equal to tank roll), with respect to a fill-volume determined for level operation (e.g., as based upon the determined212fill-volume indicator). This second numerical model may accordingly be used to determine218a roll-based correction (i.e., error) based upon the determined210vehicle roll206and the determined212tank fill-volume indicator, which determined218roll-based correction may be subtracted220from the determined216pitch-corrected estimate to determine214a fill volume that has been corrected for both pitch204and roll206.

Continuing, in an implementation using float sensor32bfor tank12b, various coefficients (Ci) may be determined relating a percentage height (h) (i.e., a percent of maximum liquid height, as indicated by float34b) and vehicle pitch (ψ) to a pitch-corrected fill-volume volume estimate, where h may be derived, for example, from a voltage signal from float sensor32b. In a model that is fifth-order in h, and third order in ψ, therefore, the pitch-corrected estimate may be determined216as the scalar:

[C1C2C3C4C5C6C7C8C9C10C11C12C13C14C15C16C17C18C19C20C21C22C23C24]·[h5⁢ψ3h4⁢ψ3h3⁢ψ3h2⁢ψ3h⁢⁢ψ3ψ3h5⁢ψ2h4⁢ψ2h3⁢ψ2h2⁢ψ2h⁢⁢ψ2ψ2h5⁢ψh4⁢ψh3⁢ψh2⁢ψh⁢⁢ψψh5h4h3h2h1].
Likewise, various coefficients (Di) may be determined relating the same percentage height (h) and vehicle roll (θ) to a roll-based fill-volume correction. Again, in a model that is fifth-order in h, and third order in θ, therefore, the roll-based correction may be determined218as the scalar:

Accordingly, pitch- and roll-corrected tank fill volume may be determined214as the scalar:

It will be understood that a reversed approach may additionally (or alternatively) be employed, where roll206is utilized to determine216an initial roll-corrected estimate, and a pitch-based correction is determined218to adjust this determined216estimate to a determined214tilt-corrected fill-volume. Likewise, it will be understood that the fifth- and third-order models presented above are intended to be examples only, and that other models (or approaches, such as look-up tables) may be possible. It will also be understood that the value of h may be corrected or calibrated in various ways (e.g., through linear calibration based on known fill volumes), and that tank fill-volume indicators other than height (or percentage height) may be additionally (or alternatively) utilized. For example, weight or pressure measurements from a load cell or other device may be utilized in place of (or as a supplemental variable to) h, in the equations noted above (or others).

With an appropriate tilt-corrected fill volume having been determined214, method200may also include controlling222various tank-filling, tank-mixing, spray application, or other spraying operations for sprayer10accordingly. As noted above, for example, various operations for sprayer10may include a primary fill operation and a secondary fill operation. For example, a carrier liquid may be pumped or otherwise fed into tank12during a primary fill operation (e.g., pumped or drained from a nurse truck or reservoir tank), with a variety of other substances diluted into the carrier liquid in a secondary fill operation. Because it may be important to precisely control the concentration of the final mixture, a PBSC method (e.g., method200) may include providing224an indicator of the determined214tilt-corrected fill-volume after the primary fill operation, then receiving226an amount of substance in the secondary fill operation based upon the determined214tilt-corrected fill-volume. For example, method200may provide224an indicator of tilt-corrected fill volume to an operator via display16, thereby allowing the operator to determine a precise amount of substance for the secondary fill operation. Additionally (or alternatively), after the primary fill operation, method200may include providing224an indicator of the determined214tilt-corrected fill-volume to a controller (e.g., controller20). The controller may then automatically calculate the appropriate amount of substance for the secondary fill operation to guide an operator (e.g., by providing to the operator an indicator of the calculated amount for the secondary fill operation) and/or actively control the secondary fill operation to ensure that the appropriate amount of substance is added.

In certain implementations, method200may similarly include controlling228one or more pumping operations. For example, method200may control228a pumping operation for tank filling (or tank drainage) based upon a determined214tilt-corrected fill volume, in order to ensure that tank12includes an appropriate (or appropriately determined214) amount of liquid during (and after) the pumping operation. Such control228may include various functions, including activating, deactivating, or otherwise regulating a pump, providing various indicators to an operator or other control system to facilitate pumping control, and so on.

Continuing, method200may include providing230an indicator of the determined214tilt-corrected fill volume to a material management (or other) system. For example, method200may communicate a tilt-corrected fill volume to a remote material management system in order to allow the remote system to accurately record and manage the distribution of various substances across an agricultural field (or otherwise). This, for example, may allow for relatively precise tracking and management of the use of various chemicals for appropriate program compliance, material tracking, and so on.

As will be appreciated by one skilled in the art, the disclosed subject matter may be embodied as a method, system, (e.g., a work vehicle control system included in sprayer10) or computer program product. Accordingly, certain embodiments may be implemented entirely as hardware, entirely as software (including firmware, resident software, micro-code, etc.) or as a combination of software and hardware aspects. Furthermore, certain embodiments may take the form of a computer program product on a computer-usable storage medium having computer-usable program code embodied in the medium.

Any suitable computer usable or computer readable medium may be utilized. The computer usable medium may be a computer readable signal medium or a computer readable storage medium. A computer-usable, or computer-readable, storage medium (including a storage device associated with a computing device or client electronic device) may be, for example, but is not limited to, an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any suitable combination of the foregoing. More specific examples (a non-exhaustive list) of the computer-readable medium would include the following: an electrical connection having one or more wires, a portable computer diskette, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or Flash memory), an optical fiber, a portable compact disc read-only memory (CD-ROM), an optical storage device. In the context of this document, a computer-usable, or computer-readable, storage medium may be any tangible medium that can contain, or store a program for use by or in connection with the instruction execution system, apparatus, or device.