Level sensors having conductive target movement sensing

Level sensors having conductive target movement sensing are disclosed. An example level sensor includes a lever operatively coupled to a sensing member, a target operatively coupled to the lever, where the target includes a conductor, an inductive coil to generate a magnetic field and measure feedback signatures associated with the target and the magnetic field, and a processor to calculate a position of the sensing member based on the feedback signatures.

FIELD OF THE DISCLOSURE

This disclosure relates generally to sensors and, more particularly, to level sensors having conductive target movement sensing.

BACKGROUND

A level sensor is typically utilized in process control systems to vary or maintain an amount of fluid stored in a tank. In particular, the level sensor includes a buoyant floating device that is operatively coupled to a switch. Based on movement of the aforementioned buoyant floating device, the switch is controlled to operate a valve fluidly coupled to the tank to maintain or adjust a level of the fluid in the tank.

SUMMARY

An example level sensor includes a lever operatively coupled to a sensing member, a target operatively coupled to the lever, where the target includes a conductor, an inductive coil to generate a magnetic field and measure feedback signatures associated with the target and the magnetic field, and a processor to calculate a position of the sensing member based on the feedback signatures.

An example method of determining a position of a sensing member of a level sensor includes providing current to an inductive coil to generate a magnetic field for a target, where the target is operatively coupled to a lever moved by the sensing member, and where the target has a conductor thereon. The method also includes obtaining, via the inductive coil, feedback signatures associated with the target and the magnetic field, and calculating, by executing instructions with at least one processor, the position of the sensing member based on the feedback signatures.

An example non-transitory machine readable medium comprises instructions stored thereon, where the instructions, which when executed, cause a processor to at least cause an inductive coil to generate a magnetic field, determine feedback signatures associated with the magnetic field and a target moved by a sensing member of a level sensor, where the target includes a conductor thereon, and calculate a position of the sensing member based on the feedback signatures.

The figures are not to scale. Instead, the thickness of the layers or regions may be enlarged in the drawings. In general, the same reference numbers will be used throughout the drawing(s) and accompanying written description to refer to the same or like parts. As used in this patent, stating that any part is in any way on (e.g., positioned on, located on, disposed on, or formed on, etc.) another part, indicates that the referenced part is either in contact with the other part, or that the referenced part is above the other part with one or more intermediate part(s) located therebetween. Connection references (e.g., attached, coupled, connected, and joined) are to be construed broadly and may include intermediate members between a collection of elements and relative movement between elements unless otherwise indicated. As such, connection references do not necessarily infer that two elements are directly connected and in fixed relation to each other. Stating that any part is in “contact” with another part means that there is no intermediate part between the two parts.

DETAILED DESCRIPTION

Level sensors having conductive target movement sensing are disclosed. Known level sensors are typically used to control an amount of fluid (e.g., liquid) stored in a tank. Typically, a flotation device of the level sensor is operatively coupled to a switch that controls a fluid valve. In particular, the fluid valve is operated by the switch to control a fluid level of the tank by filling or draining the tank. However, these known level sensors can be susceptible to wear or long-term drift over time due to implementation of numerous mechanical components and/or moving parts.

Examples disclosed herein enable accurate and reliable positional sensing of a sensing member (e.g., a floating member, a floating bob, a floater, etc.) that is affixed to a lever. In particular, the lever includes a target with a conductor (e.g., a printed conductor, a patterned conductor, a coiled target, a printed coil pattern, etc.) defined thereon. According to examples disclosed herein, a magnetic field is generated by at least one inductive coil (e.g., multiple inductive coils generating an overlapping inductive field) and resultant feedback signatures related to the target and the magnetic field are measured by the inductive coil(s) and/or magnetic field sensors as the target is moved (e.g., rotationally moved, translatably moved, etc.) and/or displaced along with the lever and the sensing member. In turn, the feedback signatures and/or changes in the feedback signatures are analyzed to calculate a position and/or displacement of the sensing member. In other words, movement of the target is measured and/or analyzed via feedback signatures or changes thereof to calculate a degree of movement of the sensing member.

Examples disclosed herein can readily adapt and/or calibrate movement of the lever and/or the sensing member with little or no mechanical adjustment. Further, examples disclosed herein also enable quick and relatively easy adjustment and setting of process control parameters (e.g., level calibration data, zero and span values, etc.) due to implementation of a control interface that can readily adapt magnetic field measurements associated with the target to a desired control of associated process control devices, for example. Further, examples disclosed herein enable storage of settings and/or parameters to reduce manual adjustments that are usually necessitated.

In some examples, a valve actuator is adjusted or controlled based on a calculated position and/or displacement of the aforementioned sensing member. In some examples, the lever pivots and/or rotates about an axis to move the target. Additionally or alternatively, the lever moves in a translational motion. In some examples, the target includes a conductor that is generally triangular or crescent shaped. Additionally or alternatively, the target includes an etched copper conductor, which is defined on a printed board (e.g., a printed circuit board, an unpowered board, etc.).

As used herein, the term “sensing member” refers to a component, assembly and/or device that moves to sense a condition. Accordingly, the “sensing member” can move in a rotational and/or translational motion. As used herein, the term “feedback signature” refers to a resultant signal and/or parameter that characterizes an effect from a generated magnetic field. Accordingly, the term “feedback signature” can relate to a signal reflected, altered and/or varied by a conductor that is actively powered or unpowered.

FIG. 1is a schematic illustration of an example level sensing system100in accordance with teachings of this disclosure. The level sensing system100of the illustrated example includes an analyzer102, and a sensor104, which includes a lever105that extends into a tank106. The level sensing system100also includes a sensing member (e.g., a floating member, a floating bob, a displacer, etc.)108operatively coupled to the lever105and disposed within the tank106, a magnetic field sensor (e.g., a magnetic field sensor array, etc.)110, a process controller (e.g., conditioning electronics)111, a programmable logic controller (PLC)112, and a valve actuator114that is operatively coupled to a valve116.

In operation, fluid120in the tank106displaces the sensing member108, thereby causing the lever105of the sensor104to move. In turn, the movement of the lever105is measured by the magnetic field sensor110. Based on the movement of the lever105, the analyzer102of the illustrated example determines a fluid height and/or an amount of the fluid120within the tank106. The example process controller111directs and/or controls the valve actuator114and, in turn, the valve116based on a desired amount of the fluid120to be stored in the tank106. In particular, the valve116controls a degree to which the fluid120enters the tank106. Additionally or alternatively, the valve116controls a degree to which the fluid120is drained from the tank106.

To control set point parameters and/or calibration associated with the analyzer102, the sensor104, the valve actuator114and/or the valve116, the example PLC112can be implemented to set and/or define parameters, instructions, etc. associated with the process controller111. In some examples, programmable functions (e.g., functions based on detected conditions, desired settings, selected configurations and/or sensor data) are stored by and/or executed by the PLC112.

In some examples, the magnetic field sensor110and the analyzer102are integral. In some such examples, the magnetic field sensor110may be placed onto a circuit board of the analyzer102as at least one discrete component. While the valve116is shown in this example, any other appropriate process control device (e.g., a fluid regulator, a pressure regulator, a fluid/hydraulic switch, etc.) can be implemented instead. Moreover, examples disclosed herein can be applied to any other appropriate application involving motion or position sensing.

FIG. 2is a partial cutaway view of an example level sensor104of the example level sensing system100ofFIG. 1. In the illustrated example, the level sensor104includes a housing202defining an internal cavity204, mounts206, the sensing member108, a stem210, a movement translator (e.g., a movement differential, a pivot, a pivot differential, etc.)212, and the lever105, which is implemented as an arm214in this example. Further, the example level sensor104includes mounts216,218, a flange mount220, and an indicator (e.g., a control panel, a user interface, etc.)222. The indicator222of the illustrated example includes a display226and a user input interface228.

To move the arm214, buoyancy of the sensing member108in the fluid120shown inFIG. 1causes a movement of the sensing member108along with the stem210. In turn, the movement translator212of the illustrated example causes a translational (e.g., a pivoting, linear) or rotational motion of the arm214, as generally indicated by a double arrow230(e.g., when the arm214is implemented as a torque tube). In other words, linear and/or rotational movement of the sensing member108is translated to movement of the arm214, which can be either translation or rotational, due to the movement translator212.

The example analyzer102shown inFIG. 1determines a position and/or a displacement of the sensing member108for a fluid level determination pertaining to the tank106based on (i.e., indirectly based on) a movement of the arm214. As will be discussed in greater detail below in connection withFIGS. 3-8, a target (e.g., a conductive target, a printed target, an etched target, etc.)302(shown inFIG. 3) is operationally coupled to the arm214and, thus, moves along with the arm214as the sensing member108is displaced. In turn, a magnetic field measurement pertaining to the target302is used to determine the position and/or the displacement of the sensing member108.

FIG. 3is a detailed view of a portion of the example level sensor104ofFIG. 2. In the illustrated view ofFIG. 3, the sensing member108is shown with the movement translator212and the arm214having a corresponding longitudinal axis301. The aforementioned example target302is implemented in the magnetic sensor110shown inFIG. 1and mounted to a pivot304, which is positioned at a distal end of the arm214in this example. The example target302includes an unpowered board (e.g., a printed circuit board, a wired board, etc.)306with a conductor (e.g., a conductor, a printed pattern, a metal pattern, an etched pattern, etc.)308. Further, a coil array (e.g., an inductive coil array)310is shown positioned proximate the example target302and includes coils (e.g., inductive coils, inductive elements, etc.)312(hereinafter312a,312b,312c,312d, etc.). The example coil array310is implemented in the magnetic field sensor110shown inFIG. 1.

To measure a degree of movement of the arm214and, thus, the sensing member108, the coils312a,312b,312c,312dof the example coil array310generate a magnetic field with overlapping inductive fields. Accordingly, movement of the conductor308relative to the coils312a,312b,312c,312d, as generally indicated by arrows320, causes a variance in magnetic field measurements obtained by the coils312a,312b,312c,312d. In turn, feedback signatures associated with this variance are utilized to calculate a movement of the target302and, thus, the sensing member108. The feedback signatures may be based on mutual inductance that is varied by relative movement between the target302and the conductor308. As will be discussed in greater detail below in connection withFIGS. 4A and 4B, the conductor308is shaped to vary and/or affect resultant feedback signatures corresponding to the magnetic field generated by the coils312a,312b,312c,312d. Further, the movement and/or position of the sensing member108is calculated based on a known relationship (e.g., a known kinematic relationship) between the sensing member108and the target302.

While four of the coils312are shown in this example, any appropriate number of the coils312can be implemented instead (e.g., one, two, three, five, ten, fifty, one hundred, etc.) depending on a desired accuracy and/or relevant degrees of motion. In this example, the coils312are at least partially composed of etched copper and the board306is implemented as a printed board (e.g., a printed circuit board, etc.) with the conductor308printed or etched thereon. However, any appropriate other materials and/or structural configurations can be implemented instead. In some examples, a single target is used to determine both linear and rotational movements of the arm214. In some other examples, the target302is disposed in the tank106while the coils312are positioned external to the tank106.

FIGS. 4A and 4Bdepict example target configurations that can be implemented in examples disclosed herein. Turning toFIG. 4A, the target302ofFIG. 3is shown with the conductor308. In particular, the example target302can be used to determine translational (or rotational) movement of the arm214(shown inFIGS. 2 and 3). In the illustrated example ofFIG. 4A, a coil location402represents at least one of the coils312is shown relative to an overall shape of the target302.

The example target302of the illustrated example is generally triangularly shaped and includes sides404, a base406and a tip (e.g., a convergence)408. In this example, movement of the target302relative to the coil location402, as generally indicated by a double arrow412, varies resultant feedback signatures and/or magnetic fields measured by at least one of the coils312and/or the magnetic field sensor110. In some examples, the aforementioned triangular shape includes rounds at any respective corners.

FIG. 4Bdepicts an alternative example target420. The example target420is similar to the target302ofFIGS. 3 and 4A, but is instead implemented to measure rotational movement and/or motion (e.g., of the arm214). The target420includes a pattern421that is generally crescent in shape and includes wider portion422with narrower distal portions424. In some examples, the distal portions424vary from one another (e.g., in length, in width, etc.) for determination of a rotational direction, for example.

In the illustrated example, the coil locations402representing the coils312a,312b,312c,312dofFIG. 3are shown relative to the target420. As the target420rotates about an axis428, as generally indicated by a double arrow430, the target420varies feedback signatures measured at the coils312a,312b,312c,312d. As a result, a rotational displacement and/or movement of the target420can be determined. In some examples, at least two of the coils312a,312b,312c,312dare concentrically arranged relative to the axis428. In other examples, at least two of the coils312a,312b,312c,312dare spaced at different distances from the axis428.

While the examples ofFIGS. 4A and 4Bdepict certain target shapes, any appropriate target shapes can be implemented instead (e.g., a rectangular shape, an oval shape, a diamond shape, a polygonal shape, etc.). Further, the examples ofFIGS. 4A and 4Bcan be used in combination with one another (e.g., a hybrid shape thereof).

FIG. 5illustrates the example inductive coil array310ofFIG. 3. As can be seen in the illustrated example, the coils312a,312b,312c,312dare shown arranged in a generally rectangular pattern on the board306. In this example, the coils312a,312b,312c,312dare each coupled (e.g., electrically coupled) to respective capacitors504(hereinafter504a,504b,504c,504d, etc.), each of which has a capacitance of approximately 160-200 picofarads (pF) (e.g., 180 pF) in this example. However, any appropriate capacitance value can be implemented instead. In some examples, the capacitors504a,504b,504c,504dare located on and/or placed onto the board306. Further, while the board306is generally depicted as being rectangular in shape, the board306can have an appropriate shape and/or outline (e.g., circular, elliptical, polygonal, etc.).

FIG. 6is a schematic overview of a level sensor analyzer600that can be implemented in examples disclosed herein. The example level sensor analyzer600can be implemented in the analyzer102, the process controller111and/or the PLC112. In this particular example, the level sensor analyzer600is implemented in the analyzer102. The level sensor analyzer600of the illustrated example includes a computational portion602, which includes a magnetic field characterizer604, a coil array controller/analyzer606, a target analyzer608and a process control director610. In some examples, the level sensor analyzer600also includes a magnetic field data storage612, which can be communicatively coupled to the computational portion602. In this example, the coil array controller/analyzer606is communicatively coupled to the coil array310.

The magnetic field characterizer604of the illustrated example determines and/or characterizes feedback signatures measured by the coil array310. In this example, the magnetic field characterizer604utilizes the feedback signatures to calculate or determine a position and/or displacement of the target302operatively coupled to the sensing member108. For example, multiple overlapping fields generated by the coils312a,312b,312c,312dgenerate feedback signatures that are obtained by the coils312a,312b,312c,312d. In particular, the generated magnetic field produces a change in current measured at the coils312a,312b,312c,312dbased on mutual inductance between the conductor308and the coils312a,312b,312c,312das the target302is moved, thereby resulting in the differences in feedback signatures (e.g., measured changes in current). In turn, the differences in the feedback signatures are used to calculate a position and/or a displacement of the target302and, thus, the sensing member108. Additionally or alternatively, the magnetic field characterizer604associates a function that relates feedback signatures and/or changes thereof to time-based movements of the sensing member108(e.g., a time-based function) to determine the position and/or the displacement of the sensing member108.

In some examples, the magnetic field characterizer604compares measured feedback signatures with stored feedback signatures to calculate the position and/or the displacement of the sensing member108and/or the target302. In some such examples, the stored feedback signatures are associated with known positions (e.g., previously measured positions) of the target302(e.g., previously recorded feedback signatures associated with known positions). Additionally or alternatively, differences in current signals measured at the coils312a,312b,312c,312ddefine the feedback signatures. In some other examples, current differences between the coils312a,312b,312c,312dare used to triangulate a position of the target302.

In the illustrated example, the coil array controller/analyzer606controls an amount of current provided to the coils312. In some examples, the coil array controller/analyzer606maintains each of the coils312at a relatively similar (e.g., the same, within 1% of one another, etc.) current level. Alternatively, the coil array controller/analyzer606controls different current values to be provided to ones of the coils312. In some examples, the coil array controller/analyzer606defines specific ones of the coils312to provide current thereto. Additionally or alternatively, the coil array controller/analyzer606controls different output phases of respective ones of the coils312.

The example target analyzer608receives magnetic field measurement signals related to the generated magnetic field and converts the signals to feedback signatures and/or data characterizing the feedback signatures. Additionally or alternatively, the target analyzer608indicates a differential magnetic field value based on the displacement of the target302.

In some examples, the process control director610is implemented to control the valve actuator114and/or the valve116based on calibration values and/or programmable instructions received from the PLC112shown inFIG. 1. For example, the process control director610utilizes a calculated position of the sensing member108based on the feedback signatures to control movement of the valve actuator114via the process controller111.

In this example, the magnetic field data storage612stores data associated with magnetic field values, feedback signatures, expected measurements, predetermined movement relationships (e.g., between the sensing member108and the arm214) for use in positional and/or movement determinations of the sensing member108. Additionally or alternatively, the magnetic field data storage612stores calibration data (e.g., current calibration data, updated calibration data, etc.) associated with the process controller111and/or the process control director610.

In some examples, a 4-20 milliamp (mA) control signal is provided by the process control director610and/or the process controller111. In some examples, a HART, Fieldbus, Profibus, Profinet and/or OPC protocols are implemented. In some such examples, these communication protocols can be used to store process sensor data (e.g., minimum values, maximum values, average values, mean values, when changes occurred, etc.).

While an example manner of implementing the level sensor analyzer600ofFIG. 6is illustrated inFIG. 6, one or more of the elements, processes and/or devices illustrated inFIG. 6may be combined, divided, re-arranged, omitted, eliminated and/or implemented in any other way. Further, the example process controller111, the example magnetic field characterizer604, the example coil array controller/analyzer606, the example target analyzer608and the example process control director610and/or, more generally, the example level sensor analyzer600ofFIG. 6may be implemented by hardware, software, firmware and/or any combination of hardware, software and/or firmware. Thus, for example, any of the example process controller111, the example magnetic field characterizer604, the example coil array controller/analyzer606, the example target analyzer608, the example process control director610and/or, more generally, the example level sensor analyzer600could be implemented by one or more analog or digital circuit(s), logic circuits, programmable processor(s), programmable controller(s), graphics processing unit(s) (GPU(s)), digital signal processor(s) (DSP(s)), application specific integrated circuit(s) (ASIC(s)), programmable logic device(s) (PLD(s)) and/or field programmable logic device(s) (FPLD(s)). When reading any of the apparatus or system claims of this patent to cover a purely software and/or firmware implementation, at least one of the example process controller111, magnetic field characterizer604, the example coil array controller/analyzer606, the example target analyzer608, and/or the example process control director610is/are hereby expressly defined to include a non-transitory computer readable storage device or storage disk such as a memory, a digital versatile disk (DVD), a compact disk (CD), a Blu-ray disk, etc. including the software and/or firmware. Further still, the example level sensor analyzer600ofFIG. 6may include one or more elements, processes and/or devices in addition to, or instead of, those illustrated inFIG. 6, and/or may include more than one of any or all of the illustrated elements, processes and devices. As used herein, the phrase “in communication,” including variations thereof, encompasses direct communication and/or indirect communication through one or more intermediary components, and does not require direct physical (e.g., wired) communication and/or constant communication, but rather additionally includes selective communication at periodic intervals, scheduled intervals, aperiodic intervals, and/or one-time events.

The example method700ofFIG. 7begins as a level of the fluid120disposed in the tank106is being measured (e.g., periodically measured) and controlled by operating the valve116via the valve actuator114.

At block702, in some examples, the coil array controller/analyzer606controls and/or provides an amount of current to the coils312of the coil array310. In some examples, the amount of current provided is varied based on a desired accuracy and/or to vary a detection range associated with the target302.

At block704, the target analyzer608directs and/or communicates with the magnetic field sensor110to obtain feedback signatures associated with a displacement and/or movement of the target302. Additionally or alternatively, a magnetic field value and/or feedback signature differential (e.g., a change in at least one magnetic field measurement over time) associated with the target302is measured.

At block708, the magnetic field characterizer604calculates a position and/or a displacement of the sensing member108based on the aforementioned feedback signatures and/or a change in the feedback signatures. The feedback signatures may pertain to changes in measured currents and/or measured current differentials. In this example, the magnetic field characterizer604determines a rotational or translational displacement of the target302to calculate a position of the sensing member108(e.g., based on known mechanical or kinematic relationships). In some examples, the magnetic field characterizer604queries expected magnetic field measurements and/or functions from the magnetic field data storage612to determine/calculate the displacement of the sensing member108based on movement of the target302.

At block710, the process control director610of the illustrated example adjusts a process based on the calculated position and/or displacement of the sensing member108. In this example, the process control director610directs the process controller111to move the valve actuator114accordingly.

At block712, it is determined whether to repeat the process. If the process is to be repeated (block712), control of the process returns to block702, Otherwise, the process ends.

FIG. 8is a block diagram of an example processor platform800structured to execute the instructions ofFIG. 7to implement the level sensor analyzer600ofFIG. 6. The processor platform800can be, for example, a server, a personal computer, a workstation, a self-learning machine (e.g., a neural network), a mobile device (e.g., a cell phone, a smart phone, a tablet such as an iPad), a personal digital assistant (PDA), an Internet appliance, a DVD player, a CD player, a digital video recorder, a Blu-ray player, a gaming console, a personal video recorder, a set top box, a headset or other wearable device, or any other type of computing device.

The processor platform800of the illustrated example includes a processor812. The processor812of the illustrated example is hardware. For example, the processor812can be implemented by one or more integrated circuits, logic circuits, microprocessors, GPUs, DSPs, or controllers from any desired family or manufacturer. The hardware processor may be a semiconductor based (e.g., silicon based) device. In this example, the processor implements the example magnetic field characterizer604, the example coil array controller/analyzer606, the example target analyzer608, the example process control director610and the process controller111.

The processor platform800of the illustrated example also includes an interface circuit820. The interface circuit820may be implemented by any type of interface standard, such as an Ethernet interface, a universal serial bus (USB), a Bluetooth® interface, a near field communication (NFC) interface, and/or a PCI express interface.

In the illustrated example, one or more input devices822are connected to the interface circuit820. The input device(s)822permit(s) a user to enter data and/or commands into the processor812. The input device(s) can be implemented by, for example, an audio sensor, a microphone, a camera (still or video), a keyboard, a button, a mouse, a touchscreen, a track-pad, a trackball, isopoint and/or a voice recognition system.

The processor platform800of the illustrated example also includes one or more mass storage devices828for storing software and/or data. Examples of such mass storage devices828include floppy disk drives, hard drive disks, compact disk drives, Blu-ray disk drives, redundant array of independent disks (RAID) systems, and digital versatile disk (DVD) drives.

The machine executable instructions832ofFIG. 7may be stored in the mass storage device828, in the volatile memory814, in the non-volatile memory816, and/or on a removable non-transitory computer readable storage medium such as a CD or DVD.

Example 1 includes a level sensor having a lever operatively coupled to a sensing member, a target operatively coupled to the lever, where the target includes a conductor, an inductive coil to generate a magnetic field and measure feedback signatures associated with the target and the magnetic field, and a processor to calculate a position of the sensing member based on the feedback signatures.

Example 2 includes the level sensor as defined in example 1, further including a valve actuator communicatively coupled to the processor.

Example 3 includes the level sensor as defined in example 2, where the valve actuator controls a valve to provide fluid to a tank in which the sensing member is at least partially disposed.

Example 4 includes the level sensor as defined in example 1, where the lever is to rotate at a pivot based on movement of the sensing member.

Example 5 includes the level sensor as defined in example 1, where the sensing member includes a float to be disposed in a tank to store fluid.

Example 6 includes the level sensor as defined in example 5, where the target is disposed in the tank.

Example 7 includes the level sensor as defined in example 1, where the conductor of the target includes a printed pattern.

Example 8 includes the level sensor as defined in example 7, where the printed pattern includes at least one of a triangular shape or a crescent shape.

Example 9 includes a method of determining a position of a sensing member of a level sensor. The method includes providing current to an inductive coil to generate a magnetic field for a target, where the target is operatively coupled to a lever moved by the sensing member, and where the target has a conductor thereon. The method also includes obtaining, via the inductive coil, feedback signatures associated with the target and the magnetic field, and calculating, by executing instructions with at least one processor, the position of the sensing member based on the feedback signatures.

Example 10 includes the method as defined in example 9, further including adjusting, by executing instructions with the at least one processor, a process control device based on the calculated position.

Example 11 includes the method as defined in example 10, where the process control device includes a valve to control an amount of fluid in a tank in which the sensing member is disposed.

Example 12 includes the method as defined in example 9, further including determining, by executing instructions with the at least one processor, zero and span values associated with the sensing member based on the feedback signatures.

Example 13 includes the method as defined in example 9, further including comparing the feedback signatures to known feedback signatures to calculate the position of the sensing member.

Example 14 includes the method as defined in example 9, where the position is calculated based on differences between the feedback signatures.

Example 15 includes a non-transitory machine readable medium comprises instructions stored thereon, where the instructions, which when executed, cause a processor to at least cause an inductive coil to generate a magnetic field, determine feedback signatures associated with the magnetic field and a target moved by a sensing member of a level sensor, where the target includes a conductor thereon, and calculate a position of the sensing member based on the feedback signatures.

Example 16 includes the non-transitory machine readable medium as defined in example 15, where the instructions cause the processor to control a process control device based on the calculated position.

Example 17 includes the non-transitory machine readable medium as defined in example 15, where the position is calculated based on changes of the feedback signatures.

Example 18 includes the non-transitory machine readable medium as defined in example 15, where the instructions cause the processor to determine zero and span values associated with the sensing member based on the feedback signatures.

Example 19 includes the non-transitory machine readable medium as defined in example 15, where the instructions cause the processor to compare the feedback signatures to known feedback signatures that correspond to known positions of the sensing member to calculate the position.

Example 20 includes the non-transitory machine readable medium as defined in example 15, where the position is calculated based on a known kinematic relationship of the sensing member to the target.

From the foregoing, it will be appreciated that example methods, apparatus and articles of manufacture have been disclosed that enable robust and accurate sensing of a position and/or displacement of a sensing member (e.g., a floating member for a level sensor). Examples disclosed herein enable reduction and/or elimination of moving parts, which can be susceptible to wear or degradation over time. Examples disclosed herein enable easy and quick adjustment of process parameters and/or calibration parameters associated with process control systems.