Torque measurement with strain gauge deviation compensation
By using technical means such as the use of strain modules and differential voltage amplifiers circuits in the torque wrench, the existing torque wrench measures the problem of low measurement accuracy at a lower torque value, and achieves higher measurement accuracy and resolution.
Patent Information
- Application Number
- CN202280096433.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2022-04-07
- Publication Date
- 2025-01-24
AI Technical Summary
Existing torque wrenches have low measurement accuracy at lower torque values, and bias problems in strain gauges components affect the resolution and accuracy of the measurement results.
The torque applied to the appliance component was used, and the composite voltage in the analog electrical signal was reduced through the combination of a large voltage voltage, the modulus converter and the processing circuit, and the measurement accuracy was improved.
The precision of the torque measurement was significantly improved at a lower torque value, reducing the impact of the bias, and improving the resolution and accuracy of the measurement result.
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Figure CN119365761A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates generally to torque application and measurement devices, and in particular to an apparatus for torque measurement, such as an electronic torque wrench. Background Art
[0002] Fasteners are often used in the assembly of performance critical components and are tightened to a specific torque level to introduce "pre-stretch" in the fastener. As torque is applied to the head of the fastener, the fastener may begin to stretch beyond the specific level of applied torque. This stretching results in a pre-stretch in the fastener, which then holds the components together. Additionally, after the required torque level has been applied, it is often necessary to further rotate the fastener past a specific angle. A common method of tightening these fasteners is with a torque wrench.
[0003] Torque wrenches can be mechanical or electronic. Mechanical torque wrenches are generally less expensive than electronic torque wrenches. There are two common types of mechanical torque wrenches, beam type and clicker type. In a beam type torque wrench, the beam bends relative to a non-deflecting beam in response to an applied torque. The amount of deflection of the bent beam relative to the non-deflecting beam indicates the amount of torque applied to the fastener. Clicker type torque wrenches have a selectable preloaded snap mechanism that has a spring to release at a specified torque, thereby producing a clicking noise.
[0004] Electronic torque wrenches tend to be more expensive than mechanical torque wrenches.When torque is applied to a fastener using an electronic torque wrench, the torque reading indicated on the display device of the electronic torque wrench is related to the preload force generated in the fastener due to the applied torque.
[0005] Many torque wrenches use a strain gauge assembly to measure applied torque. An ideal strain gauge assembly is balanced so that the strain gauge assembly produces no output without an applied torque. However, in many cases, the strain gauge assembly is unbalanced; in these cases, the strain gauge assembly has a characteristic analog signal or voltage produced by the strain gauge assembly without any applied torque. This characteristic voltage represents a bias in the strain gauge assembly, where the characteristic analog signal is the steady-state output of the strain gauge assembly without the excitation from the applied torque. Depending on the magnitude of the bias, it can have a negative impact on the resolution of the strain gauge assembly and the accuracy of the measurement results, and thus the resolution of the electronic torque wrench and the accuracy of the measurement results.
[0006] It would therefore be desirable to have a system and method that takes into account at least some of the above-mentioned issues as well as other possible issues. Summary of the invention
[0007] Exemplary embodiments of the present disclosure relate to a device for torque measurement with increased accuracy at lower torque values, such as an electronic torque wrench.The present disclosure includes, but is not limited to, the following exemplary embodiments.
[0008] Some exemplary embodiments provide an apparatus for determining a torque value of an applied torque, the apparatus comprising: a strain gauge assembly configured to measure the applied torque and to generate an analog electrical signal whose voltage varies with the applied torque, the strain gauge assembly having a characteristic analog signal generated by the strain gauge assembly in the absence of any applied torque; a differential voltage amplifier circuit configured to receive the analog electrical signal and to amplify the analog electrical signal to generate an amplified analog electrical signal, the differential voltage amplifier circuit being biased to a bias voltage calibrated to reduce a characteristic voltage in the amplified analog electrical signal; an analog-to-digital converter configured to convert the amplified analog electrical signal into an equivalent digital electrical signal; and a processing circuit configured to determine the torque value of the applied torque based on the equivalent digital electrical signal and output an indication of the torque value.
[0009] Some exemplary embodiments provide a method for determining a torque value of an applied torque, the method comprising: measuring the applied torque using a strain gauge assembly, the strain gauge assembly generating an analog electrical signal whose voltage varies with the applied torque, the strain gauge assembly having a characteristic analog signal generated by the strain gauge assembly in the absence of any applied torque; receiving the analog electrical signal at a differential voltage amplifier circuit, the differential voltage amplifier circuit amplifying the analog electrical signal to generate an amplified analog electrical signal, the differential voltage amplifier circuit being biased to a bias voltage that is calibrated to reduce a characteristic voltage in the amplified analog electrical signal; converting the amplified analog electrical signal into an equivalent digital electrical signal using an analog-to-digital converter; determining the torque value of the applied torque based on the equivalent digital electrical signal; and outputting an indication of the torque value.
[0010] These and other features, aspects and advantages of the present disclosure will become apparent by reading the following specific embodiments and the accompanying drawings, which are briefly described below. The present invention includes any combination of two, three, four or more features or elements stated in the present invention, regardless of whether such features or elements are explicitly combined or otherwise stated in the specific example embodiments described herein. The present disclosure is intended to be read as a whole, so that any separable features or elements of the present disclosure should be considered combinable in any aspect and example implementation thereof, unless the context of the present disclosure clearly stipulates otherwise.
[0011] Therefore, it will be understood that this summary of the invention is provided only to summarize some example embodiments in order to provide a basic understanding of some aspects of the present disclosure. Therefore, it will be understood that the above-mentioned example implementations are only examples and should not be interpreted as narrowing the scope or spirit of the present disclosure in any way. Other example embodiments, aspects and advantages will become apparent from the following detailed description taken in conjunction with the accompanying drawings, which illustrate by way of example the principles of some of the described example embodiments. BRIEF DESCRIPTION OF THE DRAWINGS
[0012] Having thus generally described example embodiments of the present disclosure, reference will now be made to the accompanying drawings, which are not necessarily drawn to scale, and in which:
[0013] Figure 1A and 1B An electronic torque wrench according to some exemplary embodiments of the present disclosure is shown;
[0014] Figure 2 is a block diagram of an apparatus for determining a torque value of an applied torque according to some exemplary embodiments, and the apparatus may correspond to the electronic torque wrench of FIG. 1 ;
[0015] Figure 3 According to some exemplary embodiments, a method for implementing Figure 2 The circuits of the various components of the device; and
[0016] Figure 4A , 4B 4C, 4D and 4E are flow charts illustrating various steps in a method of determining a torque value of an applied torque according to an example embodiment. DETAILED DESCRIPTION
[0017] Some embodiments of the present disclosure will now be described more fully below with reference to the accompanying drawings, in which some but not all embodiments of the present disclosure are shown. In fact, various embodiments of the present disclosure may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these example implementations are provided so that the present disclosure will be thorough and complete and will fully convey the scope of the present disclosure to those skilled in the art. The same reference numerals represent the same elements throughout.
[0018] Unless otherwise specified or clear from the context, references to first, second, etc. should not be construed as implying a particular order. A feature described as being above another feature (unless otherwise specified or clear from the context) may alternatively be below, and vice versa; similarly, a feature described as being to the left of another feature may instead be to the right, and vice versa. Furthermore, although reference may be made herein to quantitative measurements, values, geometric relationships, and the like, unless otherwise specified, any one or more (if not all) of these may be absolute or approximate to take into account acceptable variations that may occur, such as variations due to engineering tolerances, and the like.
[0019] As used herein, unless otherwise specified or clear from the context, an "or" of a set of operands is an "inclusive or," and thus is true if and only if one or more of the operands are true, as opposed to an "exclusive or," which is false when all operands are true. Thus, for example, "[A] or [B]" is true if [A] is true, or if [B] is true, or if both [A] and [B] are true. In addition, the articles "a" and "an" mean "one or more," unless otherwise specified or clear from the context to be intended in the singular. Furthermore, it should be understood that the terms "data," "content," "digital content," "information," and similar terms are sometimes used interchangeably unless otherwise specified.
[0020] Exemplary embodiments of the present disclosure generally relate to torque application and measurement devices with increased accuracy at lower torque values. Exemplary embodiments will be described primarily in the context of electronic torque wrenches. Other examples of suitable devices for torque measurement include torque testers, torque meters, torque sensors, etc. Figure 1A and 1B An electronic torque wrench 100 according to some exemplary embodiments of the present disclosure is shown. As shown, the electronic torque wrench includes a wrench body 102, a wrench head 104 (e.g., a ratchet wrench head), a grip handle 106, a housing 108, a battery assembly 110, and an electronic unit 112 having a user interface 114. In some examples, the wrench body is a tubular structure, made of steel or other rigid material, and receives the wrench head at a first end and the battery assembly at a second end, secured therein by an end cap 116. In some of these examples, the housing is mounted between and carries the electronic unit.
[0021] As shown, the front end 118 of the wrench head 104 includes a connector with a lever 120, which allows the user to select whether the torque is applied to the fastener in a clockwise (CW) direction or a counterclockwise (CCW) direction. The mechanism includes a boss 122 for receiving sockets, extensions, etc. of various sizes. The rear end 124 of the wrench head is slidably received in the wrench body 102 and rigidly fixed therein. The wrench head includes at least one vertical flat portion 126 formed between the front end and the rear end for accommodating a strain gauge assembly 128. The flat portion of the wrench head is both transverse to the rotation plane of the torque wrench 100 and parallel to the longitudinal center axis of the wrench head. The strain gauge assembly includes one or more strain gauges. In some examples, the strain gauge assembly is a full-bridge assembly, which includes four separate strain gauges on a single membrane fixed to the flat portion of the wrench head. The full-bridge strain gauge assembly mounted on the flat portion of the wrench head is collectively referred to as a strain tensor.
[0022] As also shown, the housing 108 includes a bottom 130 that is slidably received around the wrench body 104 and defines a hole 132 for receiving a top 134 that carries the electronic unit 112. The electronic unit provides a user interface 114 for operating the electronic torque wrench 100. The electronic unit includes a circuit board 136 that includes a digital display 138 and an annunciator 140 mounted thereon. This portion of the housing defines a hole for receiving a user interface that includes a power button 142, a unit selection button 144, increment / decrement buttons 146A and 146B, and three light emitting diodes (LEDs) 148A, 148B, and 148C. And when activated, the LEDs can light up green, yellow, and red, respectively.
[0023] Figure 2 An apparatus 200 for determining a torque value of an applied torque according to some example embodiments is shown. The apparatus can be embodied in a variety of different ways, and in some examples, the apparatus is an electronic torque wrench such as the electronic torque wrench 100. In other examples, the apparatus is a torque tester, a torque meter, a torque sensor, etc. As shown, the apparatus includes a strain gauge assembly 202 (e.g., the strain gauge assembly 128), a differential voltage amplifier circuit 204, an analog-to-digital converter (ADC) 206, and a processing circuit 208. In some examples where the apparatus 200 corresponds to the electronic torque wrench 100, the amplifier ADC and the processing circuit can be components of the electronic unit 112 carried by the circuit board 136.
[0024] The strain gauge assembly 202 is configured to measure the applied torque and generate an analog electrical signal having a voltage that varies with the applied torque. The differential voltage amplifier circuit 204 is configured to receive the analog electrical signal and amplify the analog electrical signal to generate an amplified analog electrical signal.
[0025] ADC 206 is configured to convert the amplified analog electrical signal (from differential voltage amplifier circuit 204) into an equivalent digital electrical signal. Processing circuit 208 is then configured to determine a torque value of the applied torque from the equivalent digital electrical signal and output an indication of the torque value. In some examples, the equivalent digital electrical signal includes digital data points; and in some of these examples, the processing circuit is configured to determine a subset of the digital data points in a moving sampling window and calculate the torque value based on a rolling average of the subset of digital data points in the moving sampling window.
[0026] The processing circuit 208 can output the indication of the torque value in a variety of different ways. In some examples, the device 200 also includes a digital display 210 (eg, digital display 138), and the processing circuit is configured to output the indication of the torque value to a digital display configured to display the torque value.
[0027] According to an exemplary embodiment of the present disclosure, the strain gauge assembly 202 has a characteristic analog signal generated by the strain gauge assembly in the absence of any applied torque. Then, the differential voltage amplifier circuit 204 is biased to a bias voltage that is calibrated to reduce the characteristic voltage in the amplified analog electrical signal. In this regard, the bias in the differential voltage amplifier circuit refers to its steady-state output voltage in the absence of a signal applied to the differential voltage amplifier circuit. Therefore, for V bias The output voltage generated by the differential voltage amplifier circuit will stay at V bias And in this regard, the characteristic voltage generated by the strain gauge assembly in the absence of any applied torque can also be considered as the bias in the strain gauge assembly.
[0028] In some examples, the characteristic analog signal is a characteristic voltage signal, and the amplified analog electrical signal for the characteristic voltage signal is an amplified voltage signal equal to the gain of the differential voltage amplifier circuit multiplied by the characteristic voltage signal, plus a bias voltage. zero As the characteristic voltage, V S is considered as the amplified voltage signal, and the gain is considered as the gain of the differential voltage amplifier circuit. In some examples, the amplified voltage signal can then be determined as follows:
[0029] V S =Gain×V zero +V bias
[0030] In some examples, ADC 206 has a reference voltage V REF In some of these examples, the bias voltage V of the calibrated differential voltage amplifier circuit 204 is bias, so that the amplified analog electrical signal V S In the absence of any applied torque, the characteristic analog signal V generated by the strain gauge assembly 202 zero The reference voltage threshold voltage V th More theoretically, for the characteristic analog signal Vzero produced by the strain gauge assembly without any applied torque, the differential voltage amplifier circuit is calibrated so that (V REF –V th )<V S <(V REF +V th The threshold voltage can be set in a variety of different ways. The differential voltage amplifier can be calibrated so that the amplified analog electrical signal V S Close to the reference voltage V REF , then, when no torque is applied to the strain gauge assembly 202, it may achieve an equivalent digital electrical signal from the ADC that is close to zero. One example of a suitable threshold voltage is 0 V. Another example of a suitable threshold is 1 mV.
[0031] In some further examples, the strain gauge assembly 202 has a voltage set to a rail voltage V CC The excitation voltage V OREG , and the reference voltage V of ADC 206 REF is set to an appropriate fraction of the mains voltage and, therefore, the excitation voltage. That is, V REF = k × V CC = k × V OREG , for k<1. In a specific example, the reference voltage V REF is set to the mains voltage V CC half of the excitation voltage V OREG In this example, k=0.5. In other suitable examples, k=0.25 or k=0.75. In some of these examples, the bias voltage V of the calibrated differential voltage amplifier circuit 204 is bias , so that the amplified analog electrical signal V S The threshold voltage V th Within, that is [(k×V OREG )–V th ]<V S <[(k×V OREG )+V th ].
[0032] In some examples, the processing circuit 208 is also configured to calibrate the bias voltage V to which the differential voltage amplifier circuit 204 is biased. biasIn some of these examples, the calibration of the bias voltage includes the processing circuit being configured to determine a temporary bias voltage V bias _ t , in some other examples, the temporary bias voltage V bias _ t can be determined as the reference voltage V of ADC 206 REF When the characteristic analog electrical signal is applied to the differential voltage amplifier circuit to generate an amplified analog electrical signal, the processing circuit may bias the differential voltage amplifier circuit to a temporary bias voltage. The processing circuit may then increase the bias voltage V in response to the amplified analog electrical signal being within a threshold voltage of the reference voltage. bias Set to a temporary bias voltage V bias _ t .
[0033] In some other examples, the bias voltage V bias The processing circuit 208 also includes a processing circuit configured to determine an absolute difference between the reference voltage and the amplified analog electrical signal. In some of these examples, when the absolute difference is less than a threshold voltage, i.e., |V REF –V S |<V th When , the amplified analog electrical signal is within the threshold voltage of the reference voltage.
[0034] In some examples, in response to the amplified analog electrical signal not being within the threshold voltage of the reference voltage, the processing circuit 208 is configured to adjust the temporary bias voltage, and bias the differential voltage amplifier circuit to the temporary bias voltage as adjusted when the characteristic analog electrical signal is reapplied to the differential voltage amplifier circuit. The processing circuit may then adjust the temporary bias voltage, and bias the differential voltage amplifier circuit to the temporary bias voltage as adjusted, until the amplified analog electrical signal is within the threshold voltage of the reference voltage.
[0035] Figure 3 300 is shown that can be used to implement various components of the apparatus 200 according to some exemplary embodiments. As shown, the circuit includes a connector 302 to connect a strain gauge assembly (e.g., strain gauge assembly 202) to a differential voltage amplifier circuit 304 that can correspond to the differential voltage amplifier circuit 204. The differential voltage amplifier circuit is configured to receive a bias voltage V bias , the differential voltage amplifier circuit is biased to the bias voltage V bias The circuit also includes an ADC 308 which may correspond to ADC 206. The ADC is configured to receive the amplified analog electrical signal V from the differential voltage amplifier circuit. S , and the ADC has a reference voltage V REF . And use VREF , the ADC is configured to convert the amplified analog electrical signal into an equivalent digital electrical signal V ADC , which is input to a processing circuit (eg, processing circuit 208).
[0036] return Figure 2 The processing circuit 208 of the example implementation of the present disclosure may be composed of one or more processors alone or in combination with one or more memories. A processing circuit is typically any computer hardware capable of processing information such as data, computer programs, and / or other suitable electronic information. A processing circuit is composed of a collection of electronic circuits, some of which may be packaged as an integrated circuit or multiple interconnected integrated circuits (sometimes more commonly referred to as "chips"). In more specific examples, a processing circuit may be implemented as or include a processor, a coprocessor, a controller, a microprocessor, a microcontroller, an application specific integrated circuit (ASIC), a field programmable gate array (FPGA), and the like.
[0037] Digital display 210 is generally any display device configured to present information in a visual or tactile form. Examples of suitable digital displays include electroluminescent (EL) displays, liquid crystal displays (LCD), light emitting diode displays (LED), plasma (P) displays, quantum dot (QD) displays, etc.
[0038] Figure 4A 4E is a flow chart showing various steps in a method 400 for determining a torque value of an applied torque according to various example embodiments of the present disclosure. The method includes measuring the applied torque using a strain gauge assembly that generates an analog electrical signal having a voltage that varies with the applied torque, the strain gauge assembly having a characteristic analog signal generated by the strain gauge assembly in the absence of any applied torque, such as Figure 4A The method includes receiving an analog electrical signal at a differential voltage amplifier circuit, the differential voltage amplifier circuit amplifying the analog electrical signal to produce an amplified analog electrical signal, the differential voltage amplifier circuit being biased to a bias voltage calibrated to reduce a characteristic voltage in the amplified analog electrical signal, as shown in block 404. The method includes converting the amplified analog electrical signal to an equivalent digital electrical signal using an analog-to-digital converter, as shown in block 406. The method includes determining a torque value of the applied torque based on the equivalent digital electrical signal, as shown in block 408. And the method includes outputting an indication of the torque value, as shown in block 410.
[0039] In some examples, the characteristic analog signal is a characteristic voltage signal, and the amplified analog electrical signal for the characteristic voltage signal is an amplified voltage signal equal to the gain of the differential voltage amplifier circuit multiplied by the characteristic voltage signal, added to a bias voltage.
[0040] In some examples, the analog-to-digital converter has a reference voltage and the bias voltage of the differential voltage amplifier circuit is calibrated so that the amplified analog electrical signal is within a threshold voltage of the reference voltage of a characteristic analog signal generated by the strain gauge assembly in the absence of any applied torque.
[0041] In some examples, the strain gauge assembly has an excitation voltage set to the rail voltage, and the reference voltage of the analog-to-digital converter is set to an appropriate fraction of the rail voltage, and thereby an appropriate fraction of the excitation voltage.
[0042] In some examples, the bias voltage of the differential voltage amplifier circuit is calibrated so that the amplified analog electrical signal is within a threshold voltage that is an appropriate fraction of the excitation voltage.
[0043] In some examples, the reference voltage of the analog-to-digital converter is set to half the rail voltage, and thereby half the excitation voltage.
[0044] In some examples, method 400 also includes calibrating a bias voltage to which the differential voltage amplifier circuit is biased, such as Figure 4B At this point, calibrating the bias voltage includes determining a temporary bias voltage, as shown in the box at block 414. Calibrating the bias voltage includes biasing the differential voltage amplifier circuit to the temporary bias voltage when the characteristic analog electrical signal is applied to the differential voltage amplifier circuit to generate an amplified analog electrical signal, as shown in block 416. And calibrating the bias voltage includes setting the bias voltage to the temporary bias voltage in response to the amplified analog electrical signal being within a threshold voltage of the reference voltage, as shown in block 418.
[0045] In some examples, a temporary bias voltage is determined at block 414 as a reference voltage for the analog-to-digital converter.
[0046] In some examples, further calibrating the bias voltage at block 412 includes determining an absolute difference between the reference voltage and the amplified analog electrical signal, such as Figure 4C 4. In some of these examples, the amplified analog electrical signal is within a threshold voltage of the reference voltage when the absolute difference is less than the threshold voltage.
[0047] In some examples, in response to the amplified analog electrical signal not being within a threshold voltage of the reference voltage, calibrating the bias voltage at 412 also includes adjusting the temporary bias voltage, such as Figure 4DCalibrating the bias voltage further includes biasing the differential voltage amplifier circuit to the adjusted temporary bias voltage when the characteristic analog electrical signal is reapplied to the differential voltage amplifier circuit, as shown in block 424. In some of these examples, the temporary bias voltage is adjusted and the differential voltage amplifier circuit is biased to the adjusted temporary bias voltage until the amplified analog electrical signal is within a threshold voltage of the reference voltage.
[0048] In some examples, the equivalent digital electrical signal includes digital data points, and determining the torque value at block 408 includes determining a subset of the digital data points in a moving sampling window, such as Figure 4E And determining the torque value includes calculating the torque value based on a rolling average of a subset of digital data points in the moving sampling window, as shown in block 428.
[0049] In some examples, the indication of the torque value is output to a digital display that displays the torque value.
[0050] As discussed above and reiterated below, the present disclosure includes, but is not limited to, the following example implementations.
[0051] Item 1. A device for determining a torque value of an applied torque, the device comprising: a strain gauge assembly configured to measure the applied torque and to generate an analog electrical signal whose voltage varies with the applied torque, the strain gauge assembly having a characteristic analog signal generated by the strain gauge assembly in the absence of any applied torque; a differential voltage amplifier circuit configured to receive the analog electrical signal and to amplify the analog electrical signal to generate an amplified analog electrical signal, the differential voltage amplifier circuit being biased to a bias voltage calibrated to reduce the characteristic voltage in the amplified analog electrical signal; an analog-to-digital converter configured to convert the amplified analog electrical signal into an equivalent digital electrical signal; and a processing circuit configured to determine the applied torque value based on the equivalent digital electrical signal and output an indication of the torque value.
[0052] Item 2. The device of Item 1, wherein the characteristic analog signal is a characteristic voltage signal, and the amplified analog electrical signal for the characteristic voltage signal is an amplified voltage signal equal to the gain of the differential voltage amplifier circuit multiplied by the characteristic voltage signal, added to a bias voltage.
[0053] Item 3. The apparatus of Item 1 or Item 2, wherein the analog-to-digital converter has a reference voltage and the bias voltage of the differential voltage amplifier circuit is calibrated so that the amplified analog electrical signal is within a threshold voltage of the reference voltage of a characteristic analog signal generated by the strain gauge assembly in the absence of any applied torque.
[0054] Clause 4. The apparatus of clause 3, wherein the strain gauge assembly has an excitation voltage set to the rail voltage, and the reference voltage of the analog-to-digital converter is set to an appropriate fraction of the rail voltage, and thereby an appropriate fraction of the excitation voltage.
[0055] Clause 5. The apparatus of clause 4, wherein the bias voltage of the differential voltage amplifier circuit is calibrated so that the amplified analog electrical signal is within a threshold voltage that is an appropriate fraction of the excitation voltage.
[0056] Clause 6. The apparatus of clause 4 or clause 5, wherein the reference voltage of the analog-to-digital converter is set to half the rail voltage and thereby half the excitation voltage.
[0057] Item 7. An apparatus of any one of items 3 to 6, wherein the processing circuit is also configured to calibrate a bias voltage to which the differential voltage amplifier circuit is biased, comprising the processing circuit being configured to at least: determine a temporary bias voltage; bias the differential voltage amplifier circuit to the temporary bias voltage when the characteristic analog electrical signal is applied to the differential voltage amplifier circuit to generate the amplified analog electrical signal; and set the bias voltage to the temporary bias voltage in response to the amplified analog electrical signal being within a threshold voltage of a reference voltage.
[0058] Clause 8. The apparatus of clause 7, wherein the processing circuit is configured to determine the temporary bias voltage as a reference voltage for the analog-to-digital converter.
[0059] Item 9. The apparatus of Item 7 or 8, wherein the processing circuit configured to calibrate the bias voltage further comprises a processing circuit configured to determine an absolute difference between a reference voltage and the amplified analog electrical signal, and wherein, when the absolute difference is less than a threshold voltage, the amplified analog electrical signal is within a threshold voltage of the reference voltage.
[0060] Item 10. An apparatus of any one of items 7 to 9, wherein in response to the amplified analog electrical signal being not within a threshold voltage of a reference voltage, the processing circuit configured to calibrate the bias voltage further comprises a processing circuit configured to: adjust a temporary bias voltage; and when the characteristic analog electrical signal is reapplied to the differential voltage amplifier circuit, bias the differential voltage amplifier circuit to the temporary bias voltage as adjusted, wherein the processing circuit is configured to adjust the temporary bias voltage and bias the differential voltage amplifier circuit to the temporary bias voltage as adjusted until the amplified analog electrical signal is within the threshold voltage of the reference voltage.
[0061] Item 11. An apparatus of any one of items 1 to 10, wherein the equivalent digital electrical signal includes digital data points, and the processing circuit configured to determine the torque value includes a processing circuit configured to perform the following operations: determine a subset of the digital data points in a moving sample window; and calculate the torque value based on a rolling average of the subset of the digital data points in the moving sample window.
[0062] Clause 12. The apparatus of any of clauses 1 to 11, wherein the processing circuit is configured to output an indication of the torque value to a digital display configured to display the torque value.
[0063] Item 13. A method for determining a torque value of an applied torque, the method comprising: measuring the applied torque using a strain gauge assembly, the strain gauge assembly generating an analog electrical signal whose voltage varies with the applied torque, the strain gauge assembly having a characteristic analog signal generated by the strain gauge assembly in the absence of any applied torque; receiving the analog electrical signal at a differential voltage amplifier circuit, the differential voltage amplifier circuit amplifying the analog electrical signal to generate an amplified analog electrical signal, the differential voltage amplifier circuit being biased to a bias voltage that is calibrated to reduce the characteristic voltage in the amplified analog electrical signal; converting the amplified analog electrical signal into an equivalent digital electrical signal using an analog-to-digital converter; determining the torque value of the applied torque based on the equivalent digital electrical signal; and outputting an indication of the torque value.
[0064] Clause 14. The method of clause 13, wherein the characteristic analog signal is a characteristic voltage signal, and the amplified analog electrical signal for the characteristic voltage signal is an amplified voltage signal equal to the gain of the differential voltage amplifier circuit multiplied by the characteristic voltage signal, added to a bias voltage.
[0065] Clause 15. The method of clause 13 or clause 14, wherein the analog-to-digital converter has a reference voltage and the bias voltage of the differential voltage amplifier circuit is calibrated so that the amplified analog electrical signal is within a threshold voltage of the reference voltage of a characteristic analog signal generated by the strain gauge assembly in the absence of any applied torque.
[0066] Clause 16. The method of clause 15, wherein the strain gauge assembly has an excitation voltage set to the rail voltage, and the reference voltage of the analog-to-digital converter is set to an appropriate fraction of the rail voltage, and thereby an appropriate fraction of the excitation voltage.
[0067] Clause 17. The method of clause 16, wherein the bias voltage of the differential voltage amplifier circuit is calibrated so that the amplified analog electrical signal is within a threshold voltage that is a suitable fraction of the excitation voltage.
[0068] Clause 18. The method of clause 16 or clause 17, wherein the reference voltage of the analog-to-digital converter is set to half the rail voltage and thereby to half the excitation voltage.
[0069] Item 19. The method of any one of items 15 to 18, wherein the method further includes calibrating a bias voltage to which a differential voltage amplifier circuit is biased, comprising at least: determining a temporary bias voltage; biasing the differential voltage amplifier circuit to the temporary bias voltage when a characteristic analog electrical signal is applied to the differential voltage amplifier circuit to produce an amplified analog electrical signal; and setting the bias voltage to the temporary bias voltage in response to the amplified analog electrical signal being within a threshold voltage of a reference voltage.
[0070] Clause 20. The method of clause 19, wherein the temporary bias voltage is determined as a reference voltage of the analog-to-digital converter.
[0071] Clause 21. The method of clause 19 or clause 20, wherein calibrating the bias voltage further comprises determining an absolute difference between the reference voltage and the amplified analog electrical signal, and wherein the amplified analog electrical signal is within a threshold voltage of the reference voltage when the absolute difference is less than the threshold voltage.
[0072] Item 22. The method of any one of items 19 to 21, wherein in response to the amplified analog electrical signal not being within a threshold voltage of a reference voltage, calibrating the bias voltage further comprises: adjusting a temporary bias voltage; and when the characteristic analog electrical signal is reapplied to the differential voltage amplifier circuit, biasing the differential voltage amplifier circuit to the temporary bias voltage as adjusted, wherein the temporary bias voltage is adjusted and the differential voltage amplifier circuit is biased to the temporary bias voltage as adjusted until the amplified analog electrical signal is within the threshold voltage of the reference voltage.
[0073] Clause 23. The method of any one of clauses 13 to 22, wherein the equivalent digital electrical signal comprises digital data points, and determining the torque value comprises: determining a subset of the digital data points in a moving sample window; and calculating the torque value based on a rolling average of the subset of digital data points in the moving sample window.
[0074] Clause 24. The method of any of clauses 13 to 23, wherein the indication of the torque value is output to a digital display that displays the torque value.
[0075] Benefiting from the teachings presented in the above description and the associated drawings, those skilled in the art of the present disclosure will think of many modifications and other embodiments of the disclosure set forth herein. Therefore, it should be understood that the present disclosure is not limited to the specific implementation disclosed, and modifications and other implementations are intended to be included in the scope of the appended claims. In addition, although the foregoing description and the associated drawings describe example implementations in the context of certain example combinations of elements and / or functions, it should be understood that different combinations of elements and / or functions can be provided by alternative implementations without departing from the scope of the appended claims. In this regard, for example, combinations of elements and / or functions different from those explicitly described above are also expected to be set forth in some of the appended claims. Although specific terms are used herein, they are used only in a general and descriptive sense, not for the purpose of limitation.
Claims
1. A device for determining a torque value of an applied torque, the device comprising: a strain gauge assembly configured to measure an applied torque and to generate an analog electrical signal having a voltage that varies with the applied torque, the strain gauge assembly having a characteristic analog signal generated by the strain gauge assembly in the absence of any applied torque; a differential voltage amplifier circuit configured to receive the analog electrical signal and amplify the analog electrical signal to produce an amplified analog electrical signal, the differential voltage amplifier circuit being biased to a bias voltage calibrated to reduce a characteristic voltage in the amplified analog electrical signal; an analog-to-digital converter configured to convert the amplified analog electrical signal into an equivalent digital electrical signal; as well as Processing circuitry is configured to determine a torque value of the applied torque from the equivalent digital electrical signal and to output an indication of the torque value.
2. The apparatus of claim 1 , wherein the analog-to-digital converter has a reference voltage and the bias voltage of the differential voltage amplifier circuit is calibrated so that the amplified analog electrical signal is within a threshold voltage of the reference voltage of the characteristic analog signal generated by the strain gauge assembly in the absence of any applied torque.
3. The apparatus of claim 2 wherein the strain gauge assembly has an excitation voltage set to a mains voltage and the reference voltage of the analog-to-digital converter is set to an appropriate fraction of the mains voltage and thereby to an appropriate fraction of the excitation voltage.
4. The device according to claim 3, wherein: The bias voltage of the differential voltage amplifier circuit is calibrated so that the amplified analog electrical signal is within a threshold voltage that is an appropriate fraction of the excitation voltage.
5. The apparatus of claim 3, wherein the reference voltage of the analog-to-digital converter is set to half the mains voltage and thereby to half the excitation voltage.
6. The apparatus of claim 2, wherein the processing circuit is further configured to calibrate the bias voltage to which the differential voltage amplifier circuit is biased, comprising the processing circuit being configured to at least: determining a temporary bias voltage; biasing the differential voltage amplifier circuit to the temporary bias voltage when the characteristic analog electrical signal is applied to the differential voltage amplifier circuit to generate the amplified analog electrical signal; and In response to the amplified analog electrical signal being within the threshold voltage of the reference voltage, the bias voltage is set to the temporary bias voltage. 7 . The apparatus of claim 6 , wherein the processing circuit is configured to determine the temporary bias voltage as the reference voltage of the analog-to-digital converter.
8. The apparatus of claim 6, wherein the processing circuit is configured to calibrate the bias voltage further comprises the processing circuit being configured to determine an absolute difference between the reference voltage and the amplified analog electrical signal, and When the absolute difference is less than the threshold voltage, the amplified analog electrical signal is within the threshold voltage of the reference voltage.
9. The apparatus of claim 6, wherein in response to the amplified analog electrical signal not being within the threshold voltage of the reference voltage, the processing circuit being configured to calibrate the bias voltage further comprises the processing circuit being configured to: adjusting the temporary bias voltage; and biasing the differential voltage amplifier circuit to the temporary bias voltage as adjusted when the characteristic analog electrical signal is reapplied to the differential voltage amplifier circuit, Wherein the processing circuit is configured to adjust the temporary bias voltage and bias the differential voltage amplifier circuit to the temporary bias voltage as adjusted until the amplified analog electrical signal is within the threshold voltage of the reference voltage.
10. The apparatus of claim 1, wherein the equivalent digital electrical signal comprises digital data points, and the processing circuitry configured to determine the torque value comprises the processing circuitry configured to: determining a subset of digital data points within a moving sample window; and The torque value is calculated from a rolling average of the subset of the digital data points in the moving sampling window.
11. A method for determining an applied torque value, the method comprising: measuring the applied torque using a strain gauge assembly that produces an analog electrical signal having a voltage that varies with the applied torque, the strain gauge assembly having a characteristic analog signal produced by the strain gauge assembly in the absence of any applied torque; receiving the analog electrical signal at a differential voltage amplifier circuit that amplifies the analog electrical signal to produce an amplified analog electrical signal, the differential voltage amplifier circuit being biased to a bias voltage calibrated to reduce the characteristic voltage in the amplified analog electrical signal; Converting the amplified analog electrical signal into an equivalent digital electrical signal using an analog-to-digital converter; determining the applied torque value according to the equivalent digital electrical signal; as well as An indication of the torque value is output.
12. The method of claim 11, wherein the analog-to-digital converter has a reference voltage and the bias voltage of the differential voltage amplifier circuit is calibrated so that the amplified analog electrical signal is within a threshold voltage of the reference voltage of the characteristic analog signal generated by the strain gauge assembly in the absence of any applied torque.
13. A method according to claim 12, wherein the strain gauge assembly has an excitation voltage set to a mains voltage and the reference voltage of the analog to digital converter is set to an appropriate fraction of the mains voltage and thereby to an appropriate fraction of the excitation voltage.
14. The method according to claim 13, wherein: The bias voltage of the differential voltage amplifier circuit is calibrated so that the amplified analog electrical signal is within a threshold voltage that is an appropriate fraction of the excitation voltage.
15. The method of claim 13, wherein the reference voltage of the analog-to-digital converter is set to half the rail voltage and thereby half the excitation voltage.
16. The method of claim 12, wherein the method further comprises calibrating the bias voltage to which the differential voltage amplifier circuit is biased, comprising at least: determining a temporary bias voltage; biasing the differential voltage amplifier circuit to the temporary bias voltage to generate the amplified analog electrical signal when the characteristic analog electrical signal is applied to the differential voltage amplifier circuit; as well as In response to the amplified analog electrical signal being within the threshold voltage of the reference voltage, the bias voltage is set to the temporary bias voltage. The method according to claim 16 , wherein the temporary bias voltage is determined as the reference voltage of the analog-to-digital converter.
18. The method of claim 16, wherein calibrating the bias voltage further comprises determining an absolute difference between the reference voltage and the amplified analog electrical signal, and When the absolute difference is less than the threshold voltage, the amplified analog electrical signal is within the threshold voltage of the reference voltage.
19. The method of claim 16, wherein in response to the amplified analog electrical signal not being within the threshold voltage of the reference voltage, calibrating the bias voltage further comprises: Adjusting temporary bias voltage; as well as biasing the differential voltage amplifier circuit to the temporary bias voltage as adjusted when the characteristic analog electrical signal is reapplied to the differential voltage amplifier circuit, The temporary bias voltage is adjusted, and the differential voltage amplifier circuit is biased to the adjusted temporary bias voltage until the amplified analog electrical signal is within the threshold voltage of the reference voltage.
20. The method of claim 11, wherein the equivalent digital electrical signal comprises digital data points, and determining the torque value comprises: determining a subset of digital data points within a moving sample window; as well as The torque value is calculated from a rolling average of the subset of the digital data points in the moving sample window.