Electronic torque wrench with automatic moment arm length measurement function

Abstract

A method is provided for determining a torque value of a torque applied by an electronic torque wrench that includes a handle, a square drive, and a strain gauge. The method includes measuring an angular velocity and a normal acceleration of the handle when the handle is rotated relative to the square driving portion, and determining a moment arm length from the square driving portion to the handle based on the angular velocity and the normal acceleration. The method includes measuring a bending moment of the rotational force at a strain gauge located at a known distance from the handle, the bending moment measured when the rotational force is applied at the handle to generate a torque at the square drive portion. A torque value is determined based on the bending moment, the moment arm length, and the known distance.

Description

Technical Field

[0001] The present disclosure generally relates to torque application and measurement devices, and more particularly to a torque measurement device, such as an electronic torque wrench. Background Art

[0002] Fasteners are commonly used to assemble performance-critical components, which are tightened to a specific torque level to introduce "pre-tension" into the fastener. When torque is applied to the head of the fastener, the fastener may begin to stretch beyond a specific level of the applied torque. This stretching results in pre-tension in the fastener, which then holds the components together. Additionally, after the desired torque level has been applied, it is often necessary to further rotate the fastener through a specific angle. A common method of tightening these fasteners is to use a torque wrench.

[0003] Torque wrenches can be mechanical or electronic types. 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 the applied torque. The amount of deflection of the bending beam relative to the non-deflecting beam indicates the amount of torque applied to the fastener. A clicker type torque wrench has a selectable pre-loaded snap mechanism that has a spring to release at a specified target torque, thereby producing a click to warn the operator to release the force on the wrench, where the applied torque is generated by the force.

[0004] Electronic torque wrenches tend to be more expensive than mechanical torque wrenches. Many electronic torque wrenches include a user interface having a human input device and an electronic visual display. An electronic torque wrench can receive a target torque through its user interface; and when torque is applied to a fastener with an electronic torque wrench, a torque reading can be indicated on the electronic visual display, which torque reading is related to the pre-tension generated in the fastener due to the applied torque. An electronic torque wrench can also warn the operator to release the force on the wrench when the applied torque reaches the target torque.

[0005] The torque value of the torque applied by an electronic torque wrench typically depends on the length of the force arm from the handle to the square drive of the torque wrench. The force arm length is typically calibrated for the torque wrench. However, in some cases, the operator uses different wrench heads with the electronic torque wrench, which increases the force arm length. In these cases, operator input is typically required to indicate the length of the wrench head in order to accurately determine the torque value. Manual input of the wrench length adds a burden to the operator and results in the accuracy of the torque value depending on the accuracy of the length input by the operator. Accordingly, there is a desire for a system and method that solves this problem and other possible problems. Summary of the Invention

[0006] Exemplary embodiments of the present disclosure relate to a device for torque measurement by automatically measuring the lever arm length, such as an electronic torque wrench. The present disclosure includes, but is not limited to, the following exemplary embodiments.

[0007] Some exemplary embodiments provide an electronic torque wrench including: a wrench body; a handle and a square drive portion located at opposite ends of the wrench body; a gyroscope and an accelerometer configured to measure the angular velocity and the normal acceleration of the handle, respectively, when the handle rotates relative to the square drive portion; a strain gauge located at a known distance from the handle, the strain gauge being configured to measure the bending moment of the rotational force at the strain gauge, the bending moment being measured when a rotational force is applied to the handle to generate a torque at the square drive portion; and a processing circuit configured to at least: determine the lever arm length from the square drive portion to the handle based on the angular velocity and the normal acceleration; and determine the torque value based on the bending moment, the lever arm length, and the known distance.

[0008] Some exemplary embodiments provide a method for determining the torque value of a torque applied by an electronic torque wrench, the electronic torque wrench including a handle and a square drive portion at opposite ends of a wrench body and including a strain gauge, the method including: measuring the angular velocity and the normal acceleration of the handle when the handle rotates relative to the square drive portion; determining the lever arm length from the square drive portion to the handle based on the angular velocity and the normal acceleration; measuring the bending moment of the rotational force at the strain gauge located at a known distance from the handle, the bending moment being measured when a rotational force is applied to the handle to generate a torque at the square drive portion; and determining the torque value based on the bending moment, the lever arm length, and the known distance.

[0009] These and other features, aspects, and advantages of the present disclosure will be apparent from the following detailed description and the accompanying drawings, which are briefly described below. The present disclosure encompasses any combination of two, three, four, or more of the features or elements set forth in the present disclosure, regardless of whether such features or elements are explicitly combined or otherwise stated in the particular exemplary embodiments described herein. The present disclosure is intended to be read as a whole such that any separable feature or element of the present disclosure should be considered combinable in any aspect and exemplary embodiment thereof unless the context of the present disclosure clearly dictates otherwise.

[0010] Accordingly, it will be understood that providing this Summary is merely to outline some example embodiments in order to provide a basic understanding of some aspects of the present disclosure. Thus, it will be appreciated that the above-described example embodiments are merely examples and should not be construed as narrowing the scope or spirit of the present invention 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

[0011] The example embodiments of the present disclosure have been described so generally above, and now reference will be made to the accompanying drawings, which are not necessarily to scale, and in which:

[0012] Figure 1A and 1B shows an electronic torque wrench according to some example embodiments of the present disclosure;

[0013] Figure 2 more specifically shows various components of the electronic unit of the electronic torque wrench of FIG. 1 according to some example embodiments;

[0014] Figure 3 shows the length of the force arm of an electronic torque wrench according to some example embodiments;

[0015] Figure 4 shows an electronic torque wrench according to some example embodiments, the electronic torque wrench including a wrench body and a plurality of wrench heads that can be removably coupled to the wrench body;

[0016] Figure 5 shows the length of the force arm of an electronic torque wrench according to some example embodiments, the length being automatically determined without operator input to indicate the length of the force arm; and

[0017] Figure 6A 、 6B 、6C, 6D, 6E, and 6F are flowcharts showing various steps in a method for determining a torque value applied by an electronic torque wrench according to various example embodiments. DETAILED DESCRIPTION

[0018] Some embodiments of the present disclosure will now be described more fully hereinafter with reference to the accompanying drawings, in which some, but not all, embodiments of the present disclosure are shown. In fact, the 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 this disclosure will be thorough and complete and will fully convey the scope of the present disclosure to those skilled in the art. Like reference numerals always denote like elements.

[0019] 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 alternatively be to the right, and vice versa. Further, although quantitative measurements, values, geometric relationships, etc. may be referred to herein, any one or more (if not all) of these may be absolute or approximate, as appropriate, to account for acceptable variations that may occur, such as those due to engineering tolerances, etc.

[0020] As used herein, unless otherwise specified or clear from the context, the "or" of a set of operands is an "inclusive or", and thus is true if and only if one or more of the operands is true, as opposed to an "exclusive or" which is false if all of the 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. Further, the articles "a", "an" denote "one or more", unless otherwise specified or clear from the context as referring to the singular form. Further, it should be understood that, unless otherwise specified, the terms "data", "content", "digital content", "information" and like terms may sometimes be used interchangeably.

[0021] Exemplary embodiments of the present disclosure generally relate to torque application and measurement devices. The exemplary embodiments will be described primarily in the context of an electronic torque wrench. Other examples of suitable torque measurement devices include torque testers, torque meters, torque transducers, and the like. Figure 1A and 1B An electronic torque wrench 100 in accordance with 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 handle 106 (e.g., a gripping handle), 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 construction made of steel or other rigid material, receiving 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 therebetween and houses the electronic unit.

[0022] As shown, the front end 118 of the wrench head 104 includes a coupler having a control lever 120 that allows a user to select whether torque is applied to the fastener in the clockwise (CW) direction or the counter - clockwise (CCW) direction. The front end also includes a boss or square drive portion 122 for receiving sockets, extensions, etc. of various sizes. The rear end 124 of the wrench head is slidably received in and rigidly fixed to the wrench body 102. The wrench head includes at least one vertical flat portion 126 formed between the front end and the rear end for receiving a strain gauge 128. The flat portion of the wrench head is both transverse to the plane of rotation of the torque wrench 100 and parallel to the longitudinal central axis of the wrench head. In some examples, the strain gauge may be embodied as an assembly of strain gauges (strain gauge assembly). In some examples, the strain gauge is a full - bridge assembly that includes four separate strain gauges on a single membrane that is fixed to the flat portion of the wrench head. The full - bridge strain gauges mounted on the flat portion of the wrench head are collectively referred to as the strain tensor.

[0023] Also as shown, the housing 108 includes a bottom 130 that is slidably received around the wrench body 102 and defines a hole 132 for receiving a top 134, where the top 134 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 a signaler 140 mounted thereon. This portion of the housing defines a hole for receiving the user interface, which includes a power button 142, unit selection buttons 144, increment / decrement buttons 146A and 146B, and three light - emitting diodes (LEDs) 148A, 148B, and 148C. And when activated, the LEDs can be lit green, yellow, and red, respectively.

[0024] Figure 2 Various components of the electronic unit 112 of the electronic torque wrench 100 are shown in more detail in accordance with some exemplary embodiments. The electronic unit includes one or more of a plurality of components that are operably coupled to each other and to other components of the electronic torque wrench. As shown, for example, the electronic unit includes one or more of a processing circuit 202, an amplifier 204, an analog - to - digital converter (ADC) 206, a gyroscope 208, an accelerometer 210, etc.

[0025] The processing circuit 202 can be configured to determine the torque value of the torque applied by the electronic torque wrench 100 (such as the torque applied to a fastener). The processing circuit can be configured to compare the applied torque with a target torque, where the target torque can be received via the user interface 114 of the electronic torque wrench. The processing circuit can output information to the operator, such as the torque value, an alarm when the applied torque is within a threshold torque range from the target torque, etc. The information can be output in a variety of different ways, such as output to a digital display 138, where the information can be presented on the digital display 138.

[0026] To determine the torque value, in some examples, the strain gauge 128 is configured to measure the bending moment of the rotational force at the strain gauge when a rotational force is applied to the handle 106 to generate torque at the square drive portion 122. In some additional examples, the strain gauge is configured to generate an analog electrical signal whose voltage varies with the bending moment at the strain gauge. The amplifier 204 is configured to increase the amplitude of the analog electrical signal to produce an amplified analog electrical signal. The ADC 206 is configured to convert the amplified analog electrical signal into an equivalent digital electrical signal. Then, the processing circuit is configured to determine the bending moment from the equivalent digital electrical signal and determine the torque value based on the bending moment. In some more specific examples, the equivalent digital electrical signal includes digital data points. 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 bending moment according to the rolling average of the subset of the digital data points in the moving sampling window.

[0027] To further illustrate the use of the rolling average, consider an example where the processing circuit 202 samples one thousand digital data points per second and uses a ten-millisecond moving sampling window. When a rotational force is applied, the processing circuit can average the first ten digital data points, one per millisecond, to produce a first equivalent digital value at time t = 0.01 seconds, where t = 0.0 seconds marks the start of the rotational force. At time t = 0.011 seconds, the processing circuit can average the digital data points taken between times t = 0.002 and t = 0.011 seconds to produce a second equivalent digital value. At time t = 0.012 seconds, the processing circuit can average the digital data points taken between times t = 0.003 and t = 0.012 seconds to produce a third equivalent digital value. And this can continue so that an equivalent digital value can be provided every millisecond until the rotational force that generates torque is no longer applied. In short, the processing circuit can utilize a digital filtering algorithm to provide a rolling average, where whenever a new digital data point is received within the moving sampling window, the oldest digital data point is discarded.

[0028] As Figure 3As shown, the torque value T of the applied torque at the square drive portion 122 can be generally expressed as the product of two things: the rotational force F at the handle 106 (which generates the applied torque), and the length of the lever arm r from the square drive portion to the handle (the handle and the square drive portion are at opposite ends of the wrench body 102). The bending moment T at the strain gauge 128 b can be similarly expressed as the product of two things: the rotational force F at the handle 106 (which generates the applied torque), and the distance d from the strain gauge to the handle. For many electronic torque wrenches 100, the lever arm length r and the distance d are known, and the processing circuit 202 can determine the torque value based on the bending moment, the lever arm length, and the distance:

[0029]

[0030] In some examples, the lever arm length can be variable. This may be the case for the electronic torque wrench 100, where the wrench head 104 is any one of a plurality of wrench heads that can be removably coupled to the wrench body 102. These wrench heads can have different lengths, which, when coupled to the wrench body, result in different lever arm lengths. Figure 4 The wrench body 102 is shown, as well as wrench heads 104A, 104B, 104C, and 104D with lengths l, l 2 、l 3 、l 4 that increase and that can be removably coupled to the wrench body. Traditional electronic torque wrenches require operator input to indicate the length of the wrench head coupled to the wrench body so that the processing circuit 202 can accurately determine the lever arm length and therefrom determine the torque value.

[0031] According to an example embodiment of the present disclosure, the processing circuit 202 can be configured to determine the lever arm length without operator input to indicate the lever arm length. In various examples, the gyroscope 208 and the accelerometer 210 are configured to measure the angular velocity and the normal acceleration of the handle 106, respectively, when the handle rotates relative to the square drive portion 122. The processing circuit is configured to determine the lever arm length from the square drive portion to the handle based on the angular velocity and the normal acceleration. And the processing circuit is configured to determine the torque value based on the bending moment T b at the strain gauge 128, the lever arm length r, and the known distance d from the strain gauge to the handle. In some of these examples, both the lever arm length and the known distance are referenced to a common point on the handle, such as the midpoint on the handle.

[0032] As Figure 5 shown, in some more specific examples, the processing circuit is configured to determine the distance from the square drive portion 122 to a common location at a second known distance d 2The radius of rotation r of the gyroscope 208 and the accelerometer 210 at [location] 2 . In this regard, the radius of rotation can be determined from the angular velocity and the normal acceleration at the gyroscope and the accelerometer. The angular velocity ω and the normal acceleration a n can be expressed relative to the velocity v as:

[0033]

[0034]

[0035] Equations (2) and (3) can be combined to yield an expression for the radius of rotation r as a function of the angular velocity and the normal acceleration 2 :

[0036]

[0037] Therefore, the radius of rotation r can be determined based on the angular velocity and the normal acceleration according to Equation (4) 2 .

[0038] As Figure 5 shown, the length of the lever arm r, the known distance d from the strain gauge 128 to the handle, and the second known distance d 2 are all referenced to a common point on the handle (e.g., the midpoint on the handle). The processing circuit is configured to: then calculate the length of the lever arm based on the radius of rotation and the second known distance, and the length of the lever arm can be expressed as r = r 2 + d 2 . Then, substituting this expression into Equation (1), the torque value can be determined as:

[0039]

[0040] In some examples, the processing circuit 202 is further configured to: derive a function that maps the bending moment T 2 + d 2 to the torque value T based on the length of the lever arm r = r b and the known distance d. The processing circuit is then configured to apply the bending moment to the function. Specifically, as shown in Equation (5), in some examples, the function includes a coefficient (r 2 + d 2 ) / d, which represents the relationship between the length of the lever arm and the known distance; and in some of these examples, the processing circuit is configured to multiply the bending moment T b by this coefficient to determine the torque value T.

[0041] The processing circuit 202 of the exemplary embodiments of the present disclosure may be constituted by a single one or more processors or by a combination of the former and one or more memories. A processing circuit is generally any computer hardware capable of processing information such as data, computer programs, and / or other suitable electronic information. The processing circuit includes a collection of electronic circuits, some of which may be encapsulated as integrated circuits or multiple interconnected integrated circuits (more commonly referred to as integrated circuits or "chips"). In a more specific example, the processing circuit may be embodied 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), etc.

[0042] Figures 6A - 6F is a flowchart showing various steps in a method 600 for determining a torque value applied by an electronic torque wrench according to various example embodiments. The electronic torque wrench includes a handle and a square drive portion at opposite ends of a wrench body and includes a strain gauge. The method includes: measuring the angular velocity and normal acceleration of the handle as the handle rotates relative to the square drive portion, as shown in block 602 of Figure 6A . The method includes: determining the length of the moment arm from the square drive portion to the handle based on the angular velocity and the normal acceleration, as shown at block 604. The method includes: measuring the bending moment of the rotational force at a strain gauge located at a known distance from the handle, the bending moment being measured when the rotational force is applied to the handle to generate a torque at the square drive portion, as shown at block 606. And the method includes: determining the torque value based on the bending moment, the moment arm length, and the known distance, as shown at block 608.

[0043] In some examples, the electronic torque wrench includes a wrench head having a square drive portion, the wrench head being any one of a plurality of wrench heads that are removably coupled to the wrench body and have different lengths, and when coupled to the wrench body, these wrench heads produce different moment arm lengths.

[0044] In some examples, both the moment arm length and the known distance are referenced to a common point on the handle.

[0045] In some examples, the electronic torque wrench further includes a gyroscope and an accelerometer, and the angular velocity and the normal acceleration are measured using the gyroscope and the accelerometer respectively at block 602.

[0046] In some examples, determining the moment arm length at block 604 includes: determining the radius of rotation from the square drive portion to the gyroscope and the accelerometer, which are both located at a second known distance from the handle, asFigure 6B as shown at block 610. And in some of these examples, determining the moment arm length further includes: calculating the moment arm length from the radius of rotation and a second known distance, as shown at block 612.

[0047] In some examples, the moment arm length, the known distance, and the second known distance are all referenced to a common point on the handle.

[0048] In some examples, method 600 further includes: deriving a function that maps a bending moment to a torque value based on the moment arm length and the known distance, as Figure 6C shown at block 614. In some of these examples, determining the torque value at block 608 includes: applying the bending moment to the function, as shown at block 616.

[0049] In some examples, the function includes a coefficient representing the relationship between the moment arm length and the known distance. In some of these examples, applying the bending moment to the function at block 616 includes multiplying the bending moment by the coefficient, as Figure 6D shown at block 618.

[0050] In some examples, measuring the bending moment at block 606 includes: receiving from a strain gauge an analog electrical signal whose voltage varies with the bending moment at the strain gauge, as Figure 6E shown at block 620. Method 600 includes: applying the analog electrical signal to an amplifier that increases the amplitude of the analog electrical signal to produce an amplified analog electrical signal, as shown at block 622. The method includes: using an analog-to-digital converter to convert the amplified analog electrical signal to an equivalent digital electrical signal, as shown at block 624. And the method includes determining the bending moment from the equivalent digital electrical signal, as shown at block 626.

[0051] In some examples, the equivalent digital electrical signal includes digital data points. In some of these examples, determining the bending moment at block 626 includes: determining a subset of the digital data points in a moving sampling window, as Figure 6F shown at block 628. And the method includes: calculating the bending moment from the rolling average of the subset of the digital data points in the moving sampling window, as shown at block 630.

[0052] As explained above and reiterated below, the present disclosure includes, but is not limited to, the following exemplary embodiments.

[0053] Article 1. An electronic torque wrench, comprising: a wrench body; a handle and a square drive portion located at opposite ends of the wrench body; a gyroscope and an accelerometer configured to measure the angular velocity and the normal acceleration of the handle respectively when the handle rotates relative to the square drive portion; a strain gauge located at a known distance from the handle, the strain gauge being configured to measure the bending moment of the rotational force at the strain gauge, the bending moment being measured when a rotational force is applied to the handle to generate a torque at the square drive portion; and a processing circuit configured to at least: determine the lever arm length from the square drive portion to the handle based on the angular velocity and the normal acceleration; and determine the torque value based on the bending moment, the lever arm length, and the known distance.

[0054] Article 2. The electronic torque wrench according to Article 1, wherein the electronic torque wrench includes a wrench head having the square drive portion, the wrench head being any one of a plurality of wrench heads that are removably coupled to the wrench body and have different lengths, and the plurality of wrench heads generate different lever arm lengths when coupled to the wrench body.

[0055] Article 3. The electronic torque wrench according to Article 1 or Article 2, wherein both the lever arm length and the known distance are referenced to a common point on the handle.

[0056] Article 4. The electronic torque wrench according to any one of Articles 1 to 3, wherein the processing circuit being configured to determine the lever arm length includes the processing circuit being configured to: determine the radius of rotation from the square drive portion to the gyroscope and the accelerometer that are both located at a second known distance from the handle; and calculate the lever arm length based on the radius of rotation and the second known distance.

[0057] Article 5. The electronic torque wrench according to Article 4, wherein the lever arm length, the known distance, and the second known distance are all referenced to a common point on the handle.

[0058] Article 6. The electronic torque wrench according to any one of Articles 1 to 5, wherein the processing circuit is further configured to: derive a function that maps the bending moment to the torque value based on the lever arm length and the known distance, and wherein the processing circuit being configured to determine the torque value includes: the processing circuit being configured to apply the bending moment to the function.

[0059] Article 7. The electronic torque wrench according to Article 6, wherein the function includes a coefficient representing the relationship between the lever arm length and the known distance, and wherein the processing circuit being configured to apply the bending moment to the function includes: the processing circuit being configured to multiply the bending moment by the coefficient.

[0060] Item 8. The electronic torque wrench according to any one of Items 1 to 7, wherein the strain gauge is configured to measure a bending moment, including that the strain gauge is configured to generate an analog electrical signal whose voltage varies with the bending moment at the strain gauge, and the electronic torque wrench further includes: an amplifier configured to increase the amplitude of the analog electrical signal to generate an amplified analog electrical signal; an analog-to-digital converter configured to convert the amplified analog electrical signal into an equivalent digital electrical signal, and wherein the processing circuit is configured to determine the bending moment from the equivalent digital electrical signal.

[0061] Item 9. The electronic torque wrench according to Item 8, wherein the equivalent digital electrical signal includes digital data points, and the processing circuit being configured to determine the bending moment includes that the processing circuit is configured to: determine a subset of the digital data points in a moving sampling window; and calculate the bending moment based on a rolling average of the subset of the digital data points in the moving sampling window.

[0062] Item 10. A method for determining a torque value of a torque applied by an electronic torque wrench, the electronic torque wrench including a handle and a square drive portion at opposite ends of a wrench body, and including a strain gauge, the method including: measuring an angular velocity and a normal acceleration of the handle when the handle rotates relative to the square drive portion; based on the angular velocity and the normal acceleration, obtaining a lever arm length from the square drive portion to the handle; measuring a bending moment of a rotational force at the strain gauge located at a known distance from the handle, the bending moment being measured when the rotational force is applied to the handle to generate a torque at the square drive portion; and based on the bending moment, the lever arm length, and the known distance, determining the torque value.

[0063] Item 11. The method according to Item 10, wherein the electronic torque wrench includes a wrench head having the square drive portion, the wrench head being any one of a plurality of wrench heads that are removably connectable to the wrench body and have different lengths, and the plurality of wrench heads generate different lever arm lengths when connected to the wrench body.

[0064] Item 12. The method according to Item 10 or Item 11, wherein both the lever arm length and the known distance are referenced to a common point on the handle.

[0065] Item 13. The method according to any one of Items 10 to 12, wherein the electronic torque wrench further includes a gyroscope and an accelerometer, and the angular velocity and the normal acceleration are measured using the gyroscope and the accelerometer, respectively.

[0066] Item 14. The method according to Item 13, wherein obtaining the lever arm length includes: determining a radius of rotation from the square drive part to the gyroscope and the accelerometer, which are both located at a second known distance from the handle; and calculating the lever arm length based on the radius of rotation and the second known distance.

[0067] Item 15. The method according to Item 14, wherein the lever arm length, the known distance, and the second known distance are all referenced to a common point on the handle.

[0068] Item 16. The method according to any one of Items 10 to 15, wherein the method further includes: deriving a function that maps the bending moment to the torque value based on the lever arm length and the known distance, and wherein determining the torque value includes applying the bending moment to the function.

[0069] Item 17. The method according to Item 16, wherein the function includes a coefficient representing the relationship between the lever arm length and the known distance, and wherein applying the bending moment to the function includes multiplying the bending moment by the coefficient.

[0070] Item 18. The method according to any one of Items 10 to 17, wherein measuring the bending moment includes: receiving an analog electrical signal from the strain gauge, the voltage of which varies with the bending moment at the strain gauge; applying the analog electrical signal to an amplifier, which increases the amplitude of the analog electrical signal to produce an amplified analog electrical signal; using an analog-to-digital converter to convert the amplified analog electrical signal into an equivalent digital electrical signal; and determining the bending moment from the equivalent digital electrical signal.

[0071] Item 19. The method according to Item 18, wherein the equivalent digital electrical signal includes digital data points, and determining the bending moment includes: determining a subset of the digital data points in a moving sampling window; and calculating the bending moment based on the rolling average of the subset of the digital data points in the moving sampling window.

[0072] Benefiting from the teachings presented in the foregoing description and the associated drawings, many modifications and other embodiments of the disclosure set forth herein will come to mind to those skilled in the art to which this disclosure pertains. Accordingly, it is to be understood that the disclosure is not limited to the specific embodiments disclosed, and that modifications and other embodiments are intended to be included within the scope of the appended claims. In addition, although the foregoing description and the associated drawings describe exemplary embodiments in the context of certain exemplary combinations of elements and / or functions, it is to be understood that different combinations of elements and / or functions can be provided by alternative embodiments without departing from the scope of the appended claims. In this regard, for example, combinations of elements and / or functions that are different from those explicitly described above are also contemplated as being possible in some of the appended claims. Although specific terms are employed herein, they are used in a generic and descriptive sense only and not for purposes of limitation.

Claims

1. An electronic torque wrench, which comprises: a wrench body; a handle and a square drive portion located at opposite ends of the wrench body; a gyroscope and an accelerometer, which are configured to: when the handle rotates relative to the square drive portion, measure the angular velocity and the normal acceleration of the handle respectively; a strain gauge located at a known distance from the handle, the strain gauge being configured to measure the bending moment of the rotational force at the strain gauge, the bending moment being measured when the rotational force is applied to the handle to generate the torque at the square drive portion; and a processing circuit, which is configured to at least: based on the angular velocity and the normal acceleration, obtain the length of the lever arm from the square drive portion to the handle; and based on the bending moment, the lever arm length and the known distance, determine the torque value.

2. The electronic torque wrench according to claim 1, wherein the electronic torque wrench includes a wrench head having the square drive portion, the wrench head being one of a plurality of wrench heads that can be removably coupled to the wrench body and having different lengths, and the plurality of wrench heads generate different lever arm lengths when coupled to the wrench body.

3. The electronic torque wrench according to claim 1, wherein both the lever arm length and the known distance are referenced to a common point on the handle.

4. The electronic torque wrench according to claim 1, wherein the processing circuit being configured to obtain the lever arm length includes the processing circuit being configured to: determine the radius of rotation from the square drive portion to the gyroscope and the accelerometer, wherein the gyroscope and the accelerometer are commonly located at a second known distance from the handle; and calculate the lever arm length based on the radius of rotation and the second known distance.

5. The electronic torque wrench according to claim 4, wherein both the lever arm length, the known distance and the second known distance are referenced to a common point on the handle.

6. The electronic torque wrench according to claim 1, wherein the processing circuit is further configured to: based on the lever arm length and the known distance, derive a function that maps the bending moment to the torque value, and wherein the processing circuit being configured to determine the torque value includes: the processing circuit being configured to apply the bending moment to the function.

7. The electronic torque wrench according to claim 6, wherein the function includes a coefficient representing the relationship between the lever arm length and the known distance, and wherein the processing circuit being configured to apply the bending moment to the function includes: the processing circuit being configured to multiply the bending moment by the coefficient.

8. The electronic torque wrench according to claim 1, wherein the strain gauge being configured to measure the bending moment includes the strain gauge being configured to generate an analog electrical signal, wherein the voltage of the analog electrical signal varies with the bending moment at the strain gauge, and the electronic torque wrench further includes: an amplifier, which is configured to increase the amplitude of the analog electrical signal to generate an amplified analog electrical signal; An analog-to-digital converter configured to convert the amplified analog electrical signal into an equivalent digital electrical signal, and wherein the processing circuit is configured to: determine the bending moment based on the equivalent digital electrical signal.

9. The electronic torque wrench according to claim 8, wherein, the equivalent digital electrical signal includes digital data points, and the processing circuit being configured to determine the bending moment includes the processing circuit being configured to: determine a subset of the digital data points in a moving sampling window; and calculate the bending moment from a rolling average of the subset of the digital data points in the moving sampling window.

10. A method for determining a torque value of a torque applied by an electronic torque wrench, the electronic torque wrench including a handle and a square drive portion at opposite ends of a wrench body and including a strain gauge, the method comprising: measuring an angular velocity and a normal acceleration of the handle when the handle rotates relative to the square drive portion; determining a lever arm length from the square drive portion to the handle based on the angular velocity and the normal acceleration; measuring a bending moment of a rotational force at the strain gauge located at a known distance from the handle, the bending moment being measured when the rotational force is applied to the handle to generate the torque at the square drive portion; and determining the torque value based on the bending moment, the lever arm length, and the known distance.

11. The method according to claim 10, wherein, the electronic torque wrench includes a wrench head having the square drive portion, the wrench head being one of a plurality of wrench heads that are removably coupled to the wrench body and have different lengths, the plurality of wrench heads generating different lever arm lengths when coupled to the wrench body.

12. The method according to claim 10, wherein, both the lever arm length and the known distance are referenced to a common point on the handle.

13. The method according to claim 10, wherein, the electronic torque wrench further includes a gyroscope and an accelerometer, and the angular velocity and the normal acceleration are measured using the gyroscope and the accelerometer, respectively.

14. The method according to claim 13, wherein, determining the lever arm length includes: determining a radius of rotation from the square drive portion to the gyroscope and the accelerometer, where the gyroscope and the accelerometer are commonly located at a second known distance from the handle; and calculating the lever arm length based on the radius of rotation and the second known distance.

15. The method according to claim 14, wherein, both the lever arm length, the known distance, and the second known distance are referenced to a common point on the handle.

16. The method according to claim 10, wherein, the method further includes: deriving a function that maps the bending moment to the torque value based on the lever arm length and the known distance, and where determining the torque value includes: applying the bending moment to the function.

17. The method according to claim 16, wherein, the function includes a coefficient representing a relationship between the lever arm length and the known distance, and Applying the bending moment to the function includes: multiplying the bending moment by the coefficient.

18. The method according to claim 10, wherein, measuring the bending moment includes: receiving an analog electrical signal from the strain gauge, the voltage of the analog electrical signal varying with the bending moment at the strain gauge; applying the analog electrical signal to an amplifier, the amplifier increasing the amplitude of the analog electrical signal to produce an amplified analog electrical signal; using an analog-to-digital converter to convert the amplified analog electrical signal into an equivalent digital electrical signal; and determining the bending moment from the equivalent digital electrical signal.

19. The method according to claim 18, wherein, the equivalent digital electrical signal includes digital data points, and determining the bending moment includes: determining a subset of the digital data points in the moving sampling window; and calculating the bending moment from a rolling average of the subset of the digital data points in the moving sampling window.

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