Apparatus and methods for multi-axis load measurement

Abstract

Apparatus and methods for multi-axis load measurement are disclosed. In one aspect, a load measuring apparatus is provided, which includes a load receiving part for receiving a load for measurement and a load reacting part for generating reaction forces based on the received load. The load reacting part and the load receiving part maintain a positional relationship with each other. The apparatus further includes one or more replaceable force acting members, each connected to the load receiving part and the load reacting part. Each force acting member comprises two pivot portions that are substantially rigid along a corresponding load measuring axis. These pivot portions are also configured to pivot at a pivot point through elastic deformation in response to pivoting forces. Additionally, each force acting member is equipped with a load measuring component for measuring the reaction forces.

Description

APPARATUS AND METHODS FOR MULTI-AXIS LOAD MEASUREMENTFIELD OF THE INVENTION

[0001] The present invention relates to the field of force measurement technology, and more particularly to apparatus and methods for multi-axis load measurement.BACKGROUND

[0002] In the field of force measurement, load cells play a pivotal role across a wide array of industrial, scientific, and engineering applications. These devices are fundamental for the precise measurement of forces and are typically available in both single-axis and multi-axis configurations. Despite their widespread use, current load cell technologies encounter several notable limitations that can affect their performance and practicality.

[0003] A common challenge in the design and implementation of load cells, particularly in multiaxis configurations, is the use of bearings or bushings. These components, while enable movement and reduce wear in mechanical systems, introduce internal friction. This friction can be unpredictable and heavily influenced by alignment issues. Misalignment can exacerbate the friction, leading to measurement inaccuracies. One consequence of this friction is hysteresis, a phenomenon where measurements do not reset to zero post-application of force, compromising accuracy.

[0004] Additionally, many high-end multi-axis load cells are manufactured from a single block of metal using intricate and costly manufacturing techniques such as Electrical Discharge Machining (EDM) or complex 6-axis machining processes. These methods come with substantial cost implications. The single-block approach to load cell construction not only escalates manufacturing expenses but also limits design flexibility. Alterations or customizations to meet specific application requirements become prohibitively expensive due to the nature of the manufacturing process. This lack of design adaptability restricts the wider application of these load cells in varied environments and for different measurement needs.

[0005] The existing load cell technologies’ drawbacks, including internal friction in mechanical systems and the high costs and rigidity of single-block manufacturing, underline the need for apparatus and methods for multi-axis load measurement that obviates or mitigates one or more limitations of the prior art.

[0006] This background information is provided to reveal information believed by the applicant to be of possible relevance to the present invention. No admission is necessarily intended, nor should be construed, that any of the preceding information constitutes prior art against the present invention.SUMMARY

[0007] The following summary is provided to facilitate an understanding of some of the innovative features unique to this invention and is not intended to be a full description. It is not intended to limit the scope of the invention.

[0008] According to an aspect, a load measuring apparatus is provided. The load measuring apparatus includes a load receiving part for receiving a load for measurement. The load measuring apparatus further includes a load reacting part for generating one or more reaction forces based on the received load. The load reacting part and the load receiving part are configured to be positionally maintained with respect to each other. Thus, the load reacting part and the load receiving part maintain a positional relationship with each other. The load measuring apparatus further includes one or more force acting members connected to the load receiving part and the load reacting part. Each force acting member is replaceable and includes corresponding two pivot portions. Each pivot portion is substantially rigid in a load measuring axis corresponding to each said force acting member. Each pivot portion is further configured to pivot each said force acting member about a pivot point via elastic deformation in response to a pivoting force. The pivoting force is a force that is received in an axis different from the corresponding load measuring axis. Each force acting member is configured to receive in the load measuring axis, via the corresponding two pivot portions, a corresponding applied force and a corresponding reaction force of the one or more reaction forces. The corresponding applied force is received from the loadreceiving part and is based on the load. The corresponding reaction force is received from the load reacting part and is opposite to and based on the corresponding applied force. Each force acting member further includes a corresponding load measuring component for measuring the corresponding reaction force.

[0009] Each force acting member is individually manufactured. In some embodiments, the one or more force acting members is two or more force acting members. In some embodiments, the one or more force acting members is six force acting members.

[0010] In some embodiments, each force acting member further includes a corresponding pivoting member and a corresponding connecting member. The corresponding pivoting member includes the corresponding two pivot portions. Each pivot portion is configured to pivot the corresponding pivoting member at the pivot point via elastic deformation in response to the pivoting force. The corresponding load measuring axis is associated with the corresponding pivoting member. The corresponding pivoting member is configured to receive in the load measuring axis, via the corresponding two pivot portions, the corresponding applied force and the corresponding reaction force. The corresponding connecting member is configured to connect the corresponding pivoting member to one of the load receiving part and the load reacting part. In some embodiments, one of the corresponding pivoting member and corresponding connecting member includes the corresponding load measuring component. In some embodiments, the corresponding load measuring component is a single axis load cell.

[0011] Each of the corresponding pivoting member and the corresponding connecting member is replaceable. Each of the corresponding pivoting member and the corresponding connecting member is individually manufactured.

[0012] According to another aspect, a method of measuring a load is provided. The method includes receiving, by a load measuring apparatus at a load receiving part, the load for measurement. The load measuring apparatus includes the load receiving part and a load reacting part for generating one or more reaction forces based on the received load. The load reacting part and the load receiving part are configured to be positionally maintained with respect to each other.The load measuring apparatus further comprises one or more force acting members connected to the load receiving part and the load reacting part. Each force acting member is replaceable and comprises corresponding two pivot portions. Each pivot portion is substantially rigid in a load measuring axis that corresponds to each said force acting member. Each pivot portion is further configured to pivot each said force acting member about a pivot point via elastic deformation in response to a pivoting force. The pivoting force is a force that is received in an axis different from the corresponding load measuring axis. Each force acting member is configured to receive in the load measuring axis, via the corresponding two pivot portions, a corresponding applied force and a corresponding reaction force of the one or more reaction forces. The corresponding applied force is received from the load receiving part and is based on the load. The corresponding reaction force is received from the load reacting part and is opposite to and based on the corresponding applied force. Each force acting member further comprises a corresponding load measuring component for measuring the corresponding reaction force. The method further includes measuring, by the load measuring apparatus, the received load.

[0013] In some embodiments, the method further includes measuring, by the load measuring apparatus, the one or more reaction forces. The received load is measured based on the measured one or more reaction forces. Each force acting member is individually manufactured.

[0014] Embodiments have been described above in conjunction with aspects of the present invention upon which they can be implemented. Those skilled in the art will appreciate that embodiments may be implemented in conjunction with the aspect with which they are described but may also be implemented with other embodiments of that aspect. When embodiments are mutually exclusive, or are incompatible with each other, it will be apparent to those skilled in the art. Some embodiments may be described in relation to one aspect, but may also be applicable to other aspects, as will be apparent to those of skill in the art.BRIEF DESCRIPTION OF THE FIGURES

[0015] Further features and advantages of the present invention will become apparent from the following detailed description, taken in combination with the appended drawings, in which:

[0016] FIG. 1 A and IB illustrate a pivot portion, according to an embodiment.

[0017] FIG. 2A and 2B illustrate a pivoting member, according to an embodiment.

[0018] FIG. 3 illustrates a load measuring apparatus, according to an embodiment.

[0019] FIG. 4 illustrates another load measuring apparatus in 2D space, according to an embodiment.

[0020] FIG. 5 illustrates a representation of a load measuring apparatus in 3D, according to an embodiment.

[0021] FIG. 6 illustrates a method of measuring a load, according to an embodiment.

[0022] FIG. 7A illustrates an example of a load measuring apparatus in 3D, according to one embodiment.

[0023] FIG. 7B illustrates another example of a load measuring apparatus in 3D, according to another embodiment.

[0024] It will be noted that throughout the appended drawings, like features are identified by like reference numerals.DETAILED DESCRIPTION

[0025] The load measuring apparatus disclosed herein is designed for measuring forces and is adaptable for both single-axis and multi-axis force measurements. This versatility makes it suitable for a variety of environments, from industrial applications to precision engineering tasks.

[0026] The apparatus includes a load receiving part, acting as an interface for the load (force) that is to be measured. It is designed to accommodate various types and magnitudes of forces, facilitating their conversion into a measurable form. This component effectively interacts with other parts of the apparatus to support improved force measurement.

[0027] Additionally, the apparatus comprises a load reacting part, functioning in conjunction with the load receiving part. Configured to generate reaction forces in response to the forces received by the load receiving part, it maintains a positional relationship with the load receiving part to facilitate the measurement process. Thus, the load reacting part and the load receiving part maintain a positional relationship with each other.

[0028] The apparatus also includes one or more force acting members connecting the load receiving and load reacting parts. These members, each featuring pivot portions, are responsible for transmitting forces from the load receiving part to the load reacting part.

[0029] The pivot portions in the force acting members are designed to exhibit compliance, enabling them to elastically deform in response to off-axis forces (pivoting forces). This design aspect allows for the effective transmission of these forces with minimal resistance. Consequently, forces that are non-load measuring axis forces for one force acting member can be effectively transmitted and adequately measured by another member where these forces align with its load measuring axis.

[0030] In some embodiments, the pivot portions are compliant in non-measuring axes and rigid along the primary load measuring axis. Their compliance allows for the necessary elastic deformation in response to off-axis forces, facilitating the handling of these forces without significantly impeding the measurement accuracy of other force acting members. Conversely, their rigidity along the load measuring axis ensures that forces applied in this direction are accurately transmitted to the load reacting part, maintaining the integrity of the force measurements.

[0031] In some configurations with six force acting members, the apparatus is enabled to measure forces and torques in a three-dimensional space. This six-axis force measurement system involves three axes for force measurement along the X, Y, and Z directions and three axes for torque measurement around these axes. The integration of these independent measurements allows the apparatus to adequately determine the overall force and torque dynamics in a three-dimensional space, making it applicable for detailed multi-dimensional force and torque analysis in fields such as robotics, aerospace, automotive testing, and biomechanics.

[0032] Overall, the design of the apparatus aims to provide potential accuracy and adaptability in force measurements across various scenarios. The configuration of the force acting members, including the pivot portions, contributes to the apparatus's ability to adequately measure forces in a range of applications, from simple single-axis measurements to complex multi-axis environments.

[0033] FIG. 1A and IB illustrate a pivot portion, according to an embodiment. In some embodiments referring to FIG. 1 A, the pivot portion 100 is engineered or configured to be rigid or substantially rigid along an axis 102 such that when a force 104 is applied in the axis 102, the pivot portion 100 maintains its form (structural integrity) and transfers 106 the force 104 along the axis 102 as illustrated. The axis 102 may be referred to as a load measuring axis or a measuring axis.

[0034] In some embodiments, referring to FIG. IB, the pivot portion 100 is engineered or configured to function as a compliant or virtual pivot. This configuration allows the pivot portion to undergo elastic deformation 114 in response to a force 108 applied in a direction different from its load measuring axis. The force 108 may be referred to as a pivoting force. The elastic deformation 114 facilitates a pivoting or rotating motion 116 around a pivot point 110. Thus, when the pivoting force 108 is applied, the pivot portion 100 pivots or rotates around the pivot point 110 by elastically deforming in response to the pivoting force as illustrated. The elastic deformation is calibrated to minimally resist the pivoting force, thus allowing movement while maintaining overall structural integrity. The degree or extent of rotation 116 shown is for illustration purposes. The extent of rotation 116 is controlled such that pivot portion maintains its rigidity in the load measuring axis 102. As such, in some embodiments, the extent of rotation 116 is relatively small to permit slight bending or pivoting at pivot point 110 while allowing rigidity in the load measuring axis.

[0035] The material for the pivot portion should ideally be both strong and elastic to allow for rigidity in the load measuring axis and compliance under pivoting forces. Materials like aluminum and steel could be suitable. These materials can provide the necessary rigidity for accurate force measurement along the measuring axis, while also possessing enough elasticity to deform under pivoting forces. The specific choice of material would depend on the required force range,environmental conditions, and precision needs of the apparatus. Advanced materials like titanium alloys might also be considered for their strength-to-weight ratio and elastic properties.

[0036] A compliant pivot may be understood by a person skilled in the art as a pivot mechanism that achieves movement through the elasticity of its material, rather than relying on traditional rigid pivot joints with bearings. This feature allows for controlled bending or flexing in certain directions while maintaining rigidity and stability in others. The design of compliant pivots provides benefits in precision mechanisms due to their minimal friction, reduced wear, low maintenance needs, and capability to handle slight misalignments or variable loads.

[0037] In designing the pivot portion, the geometry and material choice are interdependent factors for achieving the desired functionality of rigidity along the measuring axis and compliance under pivoting forces. The profile or geometry for the pivot portion depends on the application requirements, material properties, and desired range of motion. Accordingly, various geometries and profiles can be used to achieve the desired balance of compliance and rigidity. For example, the design of the pivot portion can include curved or angular shapes to provide flexibility in certain directions while maintaining strength in others. In some embodiments, the design of the pivot portion can include variable thickness where thinner sections provide compliance and thicker areas provide rigidity. In some embodiments, the design of the pivot portion can further include strategic notches or grooves to create points of controlled flexibility without compromising overall strength. Material choice further complements the chosen geometry, since the geometric features need to be tuned to match the material properties, such as elasticity, strength, and fatigue resistance. As may be appreciated by a person skilled in the art, the illustrated geometry and profile of the pivot portion 100 is an example geometry and profile that the pivot portion can have.

[0038] In some embodiments, advanced engineering techniques like finite element analysis (FEA) may be employed in the design process. FEA allows for detailed simulation and analysis of how the pivot portion will respond to various forces, enabling designers to optimize the geometry for specific mechanical properties and operational requirements.

[0039] FIG. 2A and 2B illustrate a pivoting member, according to an embodiment. Referring toFIG. 2A, the pivoting member 200 is illustrated as comprising two pivot portions 202 and 204. Each pivot portion 202 and 204 may be similar to the pivot portion 100. The pivoting member 200, including pivot portions 202 and 204, is rigid or substantially rigid along the load measuring axis 206. The load measuring axis is defined by a straight line 206 going through the two pivot portion. Accordingly, when a force 220 is received, in the load measuring axis, at the pivot portion 202 of the pivot member 200, the pivot member 200 transfers the force 220 along its load measuring axis 206. The force 220 may be transferred from the pivot portion 202, to the middle portion 208, further to the pivot portion 204 and out the pivot member as illustrated. The force 220 is transferred in a linear fashion according to the load measuring axis 206. In transferring the force along its load measuring axis 206, the pivoting member 200 maintains its rigidity and structural integrity along the load measuring axis 206.

[0040] FIG. 2B illustrates the pivoting member 200 being subj ect to a pivoting force 210 (a force in an axis different from the load measuring axis 206) at the pivot portion 202. Similar to the pivot portion 100, pivot portion 202 functions like a compliant pivot when subject to a pivoting force. Thus, when a pivoting force 210 is received at pivot portion 202, pivot portion 202 elastically deforms 212, enabling the pivoting member 200 to pivot around pivot point 214. As described herein in reference to pivot portion 100, the extent of pivoting or rotation (based on the elastic deformation 212) is controlled to allow the pivoting member to slightly bend about the pivot point 214 when experiencing a pivoting force 210 while maintaining its rigidity in the load measuring axis 206 to permit the transfer of a force 220 (a linear force) aligning with its load measuring axis 206. A similar response is expected from pivot portion 204 around its corresponding pivot point 216, should it experience a similar pivoting force. In some embodiments, the load measuring axis 206 corresponding to a pivoting member 200 (or a force acting member which includes a pivoting member) is defined by a straight line crossing the pivot points 214 and 216 of the pivot portions 202 and 204 respectively.

[0041] As described in reference to FIG. 2A and 2B, the pivoting member 200 may be viewed as a semi-rigid linkage based on its rigidity in the load measuring axis 206 and flexibility in the other axis (allowing rotation or pivoting around the pivot point of each pivot portion). Because of its dual functionality (rigidity in the load measuring axis and compliance in a non-load measuringaxis), the pivoting member permits a linear force (along the load measuring axis) to be transmitted through the member. Each pivot portion of the pivoting member is engineered to emulate the function of rotational motion facilitators, such as bearings or bushings, allowing for slight bending or pivoting. This design further reduces the friction typically encountered with such traditional components.

[0042] In some embodiments, the pivoting member 200, inclusive of the pivot portions 202 and 204, is manufactured from a single block of material. Further, because the pivoting member is individually manufactured, the pivoting member is a replaceable component. To achieve the desired functionality of the pivoting member, which includes the pivot portions, the same material properties as described in reference to pivot portion 100 are appropriate. This means selecting materials that offer the optimal balance of strength, elasticity, and fatigue resistance, such as highgrade alloys or advanced composites are appropriate. Using such materials ensures that the pivoting member, including its middle portion and pivot portions, functions effectively, maintaining structural integrity along the load measuring axis while allowing for compliant deformation under off-axis or pivoting forces. Maintaining uniformity in material across the pivoting member improves the desired and consistent functionality of the pivoting member.

[0043] FIG. 3 illustrates a load measuring apparatus, according to an embodiment. The load measuring apparatus 300 is illustrated in a two-dimensional (2D) plane (e.g., X-Y plane), the concepts of which as described herein can be extended to a 3-D space. The load measuring apparatus 300 includes a load receiving part 302 configured to receive a load for measurement. The load can be a force 350 or a torque 352 (in the X-Y plane around the Z-axis for example). The load measuring apparatus 300 further includes a load reacting part 304 for generating one or more reaction forces 358 and 360 based on the received load.

[0044] In an embodiment, the load receiving part 302 and the load reacting part 304 are positionally maintained with respect to each other, ensuring a stable spatial relationship during the operation of the load measuring apparatus. This means that the load receiving and reacting parts are statically positioned or fixedly aligned, preserving their relative positions even under varying loads. Such stationary alignment is relevant for the apparatus's structural integrity, preventingunpredictable shifts or deformations that could affect load cell readings.

[0045] The load measuring apparatus 300 includes one or more force acting members 306, 330 and 312 connected to the load receiving part 302 and the load reacting part 304. Each force acting member is connected to the load receiving part 302 and the load reacting part 304 via appropriate connecting means. In some embodiments, the force acting member 330 or 306 is a pivoting member similar to the pivoting member 200 of FIG. 2 A and 2B. In some embodiments, the force acting member 312 includes a pivoting member 308 (similar to the pivoting member 200) and a connecting member 310. Each of the force acting member 330, 306 and 312 is replaceable. In the case of force acting member 330 or 306, the member being a pivoting member can be individually manufactured, for example, from a single block. In the case of force acting member 312, each of the corresponding pivoting member 308 and the connecting member 310 can be individually manufactured. The pivoting member 308 can be connected to the connecting member 310 via any appropriate connecting means.

[0046] As described herein, each force acting member is individually manufactured and replaceable, including each of the pivoting member and its corresponding connecting member. This design may offer several benefits. Maintenance and repair become more straightforward and cost-effective since individual components can be replaced without needing to overhaul the entire apparatus. This design also allows for greater flexibility and customization, adapting the apparatus to varied measurement requirements or environmental conditions. As such, scalability is another potential advantage which allows the apparatus to be easily adapted for different operational scales, accommodating a wide range of force measurement requirements. Furthermore, the ability to replace parts as needed enhances the overall reliability and operational efficiency of the apparatus, a notable improvement over prior designs where replacing the entire unit was often necessary in case of component failure.

[0047] Each force acting member 330, 306 and 312 has a corresponding load measuring axis. For example, force acting member 306 has a load measuring axis 314, force acting member 330 has a load measuring axis 334 and the force acting member 312 has a load measuring axis 316 as illustrated. Each force acting member 330, 306 and 316 has corresponding two pivot portions.Force acting member 330 or 306, which is a pivoting member, includes two pivot portions similar to those of pivoting member 200. Force acting member 312 has two pivot portions based on its pivoting member 308, which is also similar to the pivoting member 200.

[0048] In some embodiments, each pivot portion of each force acting member 330, 306 and 312 (which refer to the pivot portion of the corresponding pivoting member of each force acting member) is similar to the pivot portion 100. Each pivot portion is rigid or substantially rigid in the corresponding load measuring axis. For example, pivot portions of force acting member 330 or 306 are rigid in the load measuring axis 334 or 314 respectively, and pivot portions of force acting member 308 are rigid in the load measuring axis 316. Further, each pivot portion of each force acting member is configured to pivot the corresponding force acting member about a pivot point via elastic deformation in response to a pivoting force. For example, each pivot portion of the force acting member 330 or 306 is configured to pivot the force acting member (e.g., the pivoting member) in response to a pivoting force. Each pivot portion of the pivoting member 308 of the force acting member 312 is configured to pivot the force acting member 312 (one or both of the pivoting member 308 and the connecting member 310) about a pivot point in response to a pivoting force.

[0049] In an embodiment, when a load (whether a force 350 or a torque 352) is applied to the load receiving part 302, the load is effectively decomposed into isolated or independent linear components through the arrangement of force acting members 330, 306 and 312 and their corresponding load measuring axis. As mentioned, each force acting member is equipped with a pivoting member, engineered to be rigid along its load measuring axis. This directed rigidity ensures that when a load, encompassing one or both of forces and moments, is applied to the apparatus, the load is effectively decomposed into isolated or independent linear forces aligned with the load measuring axes.

[0050] In the illustrated 2D scenario, the load measuring apparatus 300 is designed with load measuring axes that collectively span the entire plane to allow for measurement of forces in the plane. In the illustrated example, the load measuring axes 336 and 314 align with the Y-axis and the load measuring axis 316 aligns with the X-axis. Although the load measuring axes (314 or 334)are perpendicular with 316, they do not need to be perpendicular (orthogonal) to collectively span the entire plane. Thus, as may be appreciated, the load measuring axes may be at various angles to each other and still be capable of decomposing the load into isolated or independent linear forces within the 2D plane. An arrangement of load measuring axis that collectively spans the entire plane ensures comprehensive force measurement coverage in the plane, facilitating decomposition of forces into linear components along these the load measuring axes. Each load measuring axis provides unique information about the force component in a particular direction, as needed for decomposing the load.

[0051] While load measuring apparatus 300 includes three force acting members 306, 330 and 312, the load measuring apparatus 300 can have additional force acting members (as shown in FIG. 4 for example) where each force acting member has a corresponding load measuring axis to measure a force along said corresponding load measuring axis. Increasing the number of load measuring axis beyond what may be needed to cover or span the plane (or space) of measurement, may allow for reduced hysteresis error, as some measurement errors may cancel out. Therefore, this can result in improved accuracy of the load measurement. As such, the applied load is effectively decomposed among all force acting members for which the applied load can be decomposed among their load measuring axes. In some embodiments, one or more of the force acting members may include a load measuring component for measuring a force along a corresponding load measuring axis.

[0052] In some embodiments, depending on the plane or space of measurement, the number and arrangement of the force acting members may be such that apparatus as a whole is substantially stable or rigid. In such embodiments, when a force is applied, the force is directly and accurately transmitted through the force acting members with minimum or reduced loss or alteration due to potential movement within the apparatus or in the connection among components of the apparatus. As such, the load measuring apparatus includes at minimum an adequate or sufficient number of force acting members arranged or oriented in a way that there is no or limited mobility within the apparatus (e.g., minimum or reduced mobility among the components, e.g., the load receiving part, the force acting members, and the load reacting part). Accordingly, depending on the dimensionality of the measuring environment (e.g., 2D plane or 3D space), the number of forceacting members can be based on the extent of coverage of the measuring environment for force measurement and the stability of the load measuring apparatus. As such, the configuration of forceacting members within a load measuring apparatus is influenced by the dimensionality of the measurement environment (2D or 3D) and is determined based on: the desired coverage for force measurement within that environment and the stability of the load measuring apparatus itself.

[0053] For example, in the case of 2D, the load measuring apparatus 300 may include three force acting members to allow for stability (e.g., minimum or reduced mobility within the apparatus). One or more of the three force acting members can include a load measuring component to measure one or more of: a forces in the 2D plane (e.g., force along X-axis (Fx), force along Y-axis (Fy), and a torque or moment in the 2D plane. Increasing the number of force acting members within the load measuring apparatus may allow for improved stability, reduced hysteresis and improved measurement accuracy, as may be appreciated. For example, the load measuring apparatus 400 of FIG. 4 may allow for improved stability and measurement accuracy compared to the load measuring apparatus 300 of FIG. 3 because of the additional force acting member 412.

[0054] In some embodiments two or more force acting members may have load measuring axes that are parallel (e.g., force acting member 412 and 312 of FIG. 4). In such embodiments, the sensitivity in measuring the force(s) along these parallel load measuring axes is increased, as an increased number of load measuring components are used to measure the force(s). This setup may allow for reduced hysteresis error as some of the measurement errors cancel out, thereby improving the accuracy of force measurement. For example, force acting members 330 and 306 have parallel load measuring axes 334 and 314 respectively. Assuming each force acting member 330 and 306 includes a corresponding load measuring component 336, and 370, respectively, the sensitivity forces along the Y-axis is enhanced because two load measuring components 336 and 370 are used to measure the force in the Y-axis, where some of the error in force calculations may be mitigated in this manner.

[0055] The same concept of load decomposition into isolated or independent linear forces can be extended to three-dimensional (3D) space (shown in FIG. 5). The load measuring apparatus can extend this concept by incorporating additional axes to cover all spatial directions. In 3D, the loadmeasuring axes are arranged to ensure complete coverage of the 3D environment. Similar to the 2D case, these axes are positioned in such a way that any complex load applied — be it direct forces or moments — can be decomposed into linear forces along these axes. This arrangement can simplify the measurement process and potentially enhances the accuracy by ensuring that the majority of the measured forces are linear and aligned with the axes, thereby reducing the impact of any residual pivoting forces. The same concept of stability in terms of mobility within the apparatus may be applied to the load measuring apparatus of a 3D space, where the load measuring apparatus includes at least a minimum number force acting members arranged to stabilize the load measuring apparatus (i.e., minimal or reduced mobility within the apparatus) to allow for direct and accurate transmission of the forces within the apparatus.

[0056] In some embodiments, the load measuring apparatus is also designed to minimize the impact of pivoting forces that may arise due to mechanical design limitations. The pivoting members of the force acting members, while being rigid in the direction of the load measuring axes, allows some flexibility in other directions. This design ensures that pivoting or off-axis forces, which could lead to pivoting, are minimized. The strategic placement of the load measuring axes further reduces these effects, maintaining the integrity of linear force measurements and enhancing the accuracy and reliability of the apparatus.

[0057] By effectively breaking down an applied load into manageable linear components and reducing the influence of non-linear forces, the load measuring apparatus 300 may be well-suited for a wide range of applications that require precise force measurement.

[0058] Accordingly, referring to FIG. 3, when a load, e.g., force 350 or torque 352 or a combination, is applied to the load receiving part 302, the load is effectively decomposed into isolated or independent linear forces 354, 332 and 356 based on the arrangement of the force acting members 306, 330 and 312 and their corresponding load measuring axis 314, 334 and 316 respectively. Thus, each force acting member is configured to receive in the load measuring axis, via the corresponding two pivot portions, a corresponding applied force. The force acting member 306 receives the applied force 354, force acting member 330 receives the applied force 332, and force acting member 312 receives applied force 356. The corresponding applied force is receivedfrom the load receiving part 302 and is based on the load. Each force acting member is further configured to receive in the load measuring axis, via the corresponding two pivot portions, a corresponding reaction force of the one or more reaction forces. Each force acting member transfers the received load to the load reacting part 304 and receives from the load reacting part 304 a reaction force that is opposite to and based on the corresponding applied force. This reaction force is inherently opposite in direction to the applied force and is expected to be proportional in magnitude, under ideal operational conditions. For example, force acting member 306 transmits the corresponding applied force 354 to the load reacting part, which generates reaction force 358. Force acting member 330 transmits the corresponding applied force 332 to the load reacting part, which generates reaction force 338. Similarly, force acting member 312 transmits the applied force 356, via the pivoting member 308 and the connecting member 310, to the load reacting part, which generates reaction force 360.

[0059] In some embodiments, one or more of the force acting members 306, 330 and 312 includes a corresponding load measuring component 370, 336 and 372, respectively, for measuring the corresponding reaction force. In force acting member 306 or 336, the load measuring component 370 or 336, respectively, is integrated with or attached to the pivoting member. In force acting member 312, the load measuring component 372 is integrated with or attached to the connecting member 310. In some embodiments, in the case of force acting member 312, the load measuring component 372 can be attached to the pivoting member 308.

[0060] The use of a pivoting member (as part of each force acting member) in the load measuring apparatus allows for reduced or minimal friction in non-measuring axes. The system may still generate some forces in the non-measuring axis, and these forces can be considered in the calibration process.

[0061] The load measuring component may be any appropriate type of load cell. For example, the load measuring component can be any one of: multi-axis load cell, strain gauge load cell, hydraulic load cell, pneumatic load cell, capacitive load cell or other appropriate load cells.

[0062] In some embodiments, the load measuring component is a single axis load cell, which isaligned with the linearly defined load measuring axis of the force acting members. As described herein, the force acting members are designed to respond to force along a singular, linear path, aligning with the capabilities of a single-axis load cell. Single axis load cell provides a cost- effective solution for linear force measurement. Proper alignment of the single-axis load cell with the load measuring axis is relevant to ensure accurate force readings.

[0063] In the manufacturing of the different components (e.g., pivoting member, connecting member, load receiving part, load reacting part) of the load measuring apparatus, standard industry practices can be employed. This includes the use of precision machining (e.g., standard lathe) for the intricate components like the pivoting member to ensure accuracy and smooth operation. The choice of manufacturing techniques will depend on the material properties, design specifications, and production scale, ensuring that each part meets the necessary precision and quality standards for the apparatus's effective functioning.

[0064] In the design of the load measuring apparatus, the connections between its various components, such as the force acting members, pivoting members, connecting members, load receiving part, and load reacting part, are established through common, reliable means that are widely used in mechanical assemblies to ensure durability and precision. They may include methods such as bolting, welding, or the use of precision fasteners, ensuring that each component is securely attached and aligned with the others. Additionally, specialized joining techniques such as adhesive bonding, which uses a chemical adhesive to bond materials, or interference fit, where components are designed to fit tightly into each other, may be employed depending on the material properties and the operational requirements of the apparatus. The nature of these connections is chosen to guarantee that the apparatus remains a cohesive, stable unit, capable of accurately transmitting and measuring forces without any compromise in structural integrity.

[0065] FIG. 4 illustrates another load measuring apparatus in 2D space, according to an embodiment. The load measuring apparatus 400 is similar to the load measuring apparatus 300 with the addition of the extra force acting member 412, which comprises a pivoting member 408 and a connecting member 410. Compared to the load measuring apparatus 300, as described herein, the addition of the force acting member 412 in the load measuring apparatus 400 may allow forimproved stability and measurement accuracy.

[0066] As illustrated, the force acting member 412 may have a corresponding load measuring axis 408. Further, the force acting member 412 receives a corresponding linear applied force 456, based on the applied load (350 or 352), along the load measuring axis 416. The force acting member 412 transmits the corresponding applied force 456 to the load reacting part 304, which generates a reaction force 460 as illustrated. In some embodiments, force acting member 412 may further comprise a load measuring component 472.

[0067] In an embodiment, force acting members 412 and 312 have parallel load measuring axes 334 and 314 respectively, which align with the X-axis. Assuming each force acting member 412 and 132 includes a corresponding load measuring component 472, and 372, respectively, the sensitivity forces along the X axis is enhanced because two load measuring components 472 and 372 are used to measure the force in the X-axis, where some of the error in force calculations may be mitigated in this manner.

[0068] In embodiments in which a force acting member includes a connecting member, the connecting member serves as a link (a structural link) between the pivoting member and either the load receiving part or the load reacting part. The connecting member facilitates the effective transmission of forces, from the load receiving part to the pivoting member, and from there, to the load reacting part. This transmission is relevant for the generation of the reaction force that is opposite to and based on the applied force. The connecting member can further define and customize the load measuring axis of a force acting member as the connecting member plays a role in positioning the pivoting member, thereby determining the orientation of the load measuring axis. This capability can allow for tailored adjustments of the apparatus to suit specific measurement needs or scenarios.

[0069] In some embodiments of the load measuring apparatus, the force acting member comprises multiple connecting members in conjunction with a pivoting member. The arrangement of these components can vary based on the specific design and application requirements of the apparatus. In some configurations, the pivoting member may be directly connected to the loadreceiving part. Alternatively, the pivoting member could be linked to the load reacting part, or positioned between two connecting members, providing additional structural and functional versatility. In such embodiments, the placement of the load measuring component can vary within the force acting member, offering flexibility in measuring the reaction forces effectively.

[0070] Depending on the application, the number of load measuring axes (which is based on the number of force acting member) which may be employed may vary. As described herein, in 2D plane, an appropriate number and arrangement of load measuring axes may be used to cover the plane. Similarly, in 3D space, an appropriate number and arrangement of load measuring axes may be used to cover the 3D environment.

[0071] For example, in some embodiments, to measure forces and moments in six degrees of freedom, e.g., six-axis load cell, six load measuring axis (and thus six force acting members) may be used in a load measuring apparatus. The six load measuring axes may be arranged, based on the arrangement of the corresponding six force acting members, such that the load measuring apparatus measures the three linear forces along the x, y, and z axes (typically forward / backward, left / right, up / down) and three rotational moments (torques) about those same three axes. Six-axis measurements are relevant in aeronautics, particularly for unmanned aerial vehicles (UAVs), such as drones. A six-axis load cell, as per an embodiment, can be utilized for measuring forces and torques in motors and propellers, testing drones in wind tunnels, and analyzing gas engines equipped with propellers. These measurements are valuable for drone, motor, and propeller manufacturers during research and development for characterization, optimization, and selection. They are also relevant in production and operational phases, ensuring high performance and reliability of these components.

[0072] An example arrangement of a load measuring apparatus with six load measuring axis that can be used for six-axis measurement is shown in FIG. 5. FIG. 5 illustrates a representation of a load measuring apparatus in 3D, according to an embodiment. The load measuring apparatus 500 is shown as a 3D wireframe model of a six-axis load measuring apparatus with force acting members arrayed in two levels of concentric circles, according to an embodiment. The six-axis load measuring apparatus 500 includes six force acting members, each extending along a uniqueaxis corresponding to a load measuring axis. These load measuring axes are shown as 510, 512, 514, 516, 518, and 520. The six force acting members are organized into two concentric circular arrangements 502 and 504, which represent the apparatus's load measuring axes at different vertical heights, correlating to the positions of the load receiving part and the load reacting part, respectively. This height refers to the positional relationship that is maintained between the load receiving part and the load reacting part. This configuration allows for the independent measurement of forces along the X, Y, and Z axes, as well as the calculation of torques around these axes. Adjustments to the 'height', the vertical spacing between the load receiving part and the load reacting part, and the 'diameter', the size of the circular arrangements 502 and 504, can modify the apparatus's measurement range. A larger diameter provides a greater torque arm, enabling the measurement of higher torques. This scalable and adaptable design is suited for a variety of applications requiring precise multi-axis force and torque measurement.

[0073] In FIG. 5, the load measuring apparatus 500 includes six load measuring axes based on the six force acting members. While six load measuring axes may be sufficient to cover the 3D space, in some embodiments, additional load measuring axes may be incorporated to improve accuracy of measurement.

[0074] In some embodiments, the load measuring apparatus can be tailored for applications involving significant vibration, such as those with gas engines. To ensure measurement accuracy in these conditions, the apparatus can incorporate dampers (mechanical filter or vibrational absorber). These components help maintain the stability and reliability of the apparatus under vibrational stress. Additionally, other protective elements (e.g., shock absorbers, thermal insulation, environmental seals, electromagnetic interference shielding, reinforced casted, etc.) may be included to enhance durability and performance in varied operational environments, making the apparatus versatile and robust for industrial use.

[0075] FIG. 6 illustrates a method of measuring a load, according to an embodiment. The method 600 includes receiving 601, by a load measuring apparatus at a load receiving part, the load for measurement. The load measuring apparatus includes the load receiving part and a load reacting part for generating one or more reaction forces based on the received load. The load reacting partand the load receiving part are configured to be positionally maintained (or maintain a positional relationship) with respect to each other. The load measuring apparatus further comprises one or more force acting members connected to the load receiving part and the load reacting part. Each force acting member is replaceable and comprises corresponding two pivot portions. Each pivot portion is substantially rigid in a load measuring axis that corresponds to each said force acting member. Each pivot portion is further configured to pivot each said force acting member about a pivot point via elastic deformation in response to a pivoting force. The pivoting force is a force that is received in an axis different from the corresponding load measuring axis. Each force acting member is configured to receive in the load measuring axis, via the corresponding two pivot portions, a corresponding applied force and a corresponding reaction force of the one or more reaction forces. The corresponding applied force is received from the load receiving part and is based on the load. The corresponding reaction force is received from the load reacting part and is opposite to and based on the corresponding applied force. Each force acting member further comprises a corresponding load measuring component for measuring the corresponding reaction force. The method 600 further includes measuring 602, by the load measuring apparatus, the received load.

[0076] FIG. 7A illustrates an example of a load measuring apparatus in 3D, according to one embodiment. FIG. 7B illustrates another example of a load measuring apparatus in 3D, according to another embodiment. Each of the load measuring apparatuses 700 (FIG. 7A) and 750 (FIG. 7B) is a six-axis load measuring apparatus (similar to the load measuring apparatus 500) and includes six force-acting members as shown.

[0077] As described herein, a force acting member, which includes a pivoting member and a connecting member, can have different configurations. For example, either the pivoting member or the connecting member can be connected to either the load receiving part or the load reacting part. In load measuring apparatus 700, the force acting members are configured with the pivoting members connected to the load-reacting part 704A and the connecting members connected to the load-receiving part 702A.

[0078] In load measuring apparatus 750, some force acting members, e.g., force acting member710, are configured with the connecting members connected to the load receiving part 702B and the pivoting members connected to the load reacting part 704. Further, in load measuring apparatus 750, some force acting members, e.g., force acting member 712, are configured with the pivoting members connected to the load receiving part 702B and the connecting members connected to the load reacting part 704.

[0079] In some embodiments, the method further includes measuring, by the load measuring apparatus, the one or more reaction forces. The received load is measured based on the measured one or more reaction forces.

[0080] As may be appreciated, in some embodiments, appropriate mathematical or computational methods are used to combine the individual force components to obtain the applied force or torque. This could involve one or more of simple vector addition for linear forces or more complex algorithms for non-linear systems. For example, if the force components are represented as vectors, they can be summed using vector addition principles to yield the resultant force. In more complex scenarios, where non-linearities are present, specialized computational algorithms, such as finite element analysis or iterative solvers, may be employed to accurately determine the combined force or torque.

[0081] In some embodiments, appropriate calibration or correction methods may be used to ensure the accuracy of the combined force measurement. This might involve compensating for sensor inaccuracies or environmental factors. Initial calibration may include applying known forces to the system and adjusting the sensors to match these known values. Periodic recalibration may be scheduled to maintain measurement accuracy overtime. Additionally, real-time calibration methods may dynamically adjust sensor readings to account for drift or changes in environmental conditions such as temperature or humidity.

[0082] In some embodiments, data processing methods or software may be used to process the measured data from individual sensors. This could include filtering, noise reduction, and data integration techniques. Filtering techniques, such as low-pass or Kalman filters, can remove noise from the sensor data. Noise reduction algorithms help to enhance signal quality, ensuring that themeasured forces are accurate. Data integration methods may combine readings from multiple sensors to provide a cohesive and comprehensive measurement output.

[0083] In some embodiments, the measured individual forces and combined force or torque may be displayed or outputted to the user via a user interface. This might involve a graphical interface, digital readout, or integration with other systems. The user interface could provide visual representations of the force vectors and the resultant force, making it easier for users to interpret the data. Integration with other systems may allow for automated reporting, data logging, or further analysis in external software applications.

[0084] In some embodiments, appropriate methods may be used for analyzing and compensating for potential errors in the combined measurement. This could involve statistical methods or machine learning techniques to enhance accuracy. Error detection algorithms can identify anomalies or inconsistencies in the measurements, prompting corrective actions. Statistical methods, such as regression analysis, can be used to model and correct systematic errors. Machine learning algorithms may learn from historical data to predict and compensate for potential inaccuracies in real-time.

[0085] In some embodiments, to ensure redundancy and reliability in the measurement process, methods may involve using multiple sensors for the same force component and averaging their readings or having backup systems in place. Redundancy ensures that if one sensor fails, others can continue to provide accurate measurements. Averaging readings from multiple sensors can reduce the impact of any single sensor’s error. Backup systems, such as duplicate sensors or alternative measurement methods, can provide additional reliability and confidence in the measurement results.

[0086] The term 'rigid,' as used herein, for example, when referring to the pivot member and pivot portions along the load measuring axis, denotes their inherent structural stiffness. This characterization indicates that these components are intentionally designed to be mechanically solid and inflexible, thus maintaining their shape under the force applied in this axis. They exhibit a marked resistance to deformation, ensuring that they do not significantly bend, flex, or undergosignificant elastic deformation under operational loads. This aspect of rigidity is relevant for accurate force transmission as it preserves the integrity of measurements along the primary force measurement direction. In this context, therefore, 'rigid' in relation to the pivot member and portions conveys the quality of being structurally unyielding and non-deformable along the load measuring axis.

[0087] It will be appreciated that, although specific embodiments have been described herein for purposes of illustration, various modifications may be made without departing from the scope of the technology. The specification and drawings are, accordingly, to be regarded simply as an illustration of the invention as defined by the appended claims, and are contemplated to cover any and all modifications, variations, combinations or equivalents that fall within the scope of the present invention. It is to be understood that features of the invention described with respect to certain embodiments may be combined with features of other embodiments, and such combinations are contemplated within the scope of the invention. Substitutions and variations of features described herein are also contemplated and should be considered within the ambit of the present invention. As such, components of this invention might be used in various configurations and combinations. The components and configurations can be interchanged or integrated with other systems, and such variations are within the scope of the invention.

[0088] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The present invention is described herein with reference to particular applications and uses. However, it is to be appreciated that the invention is not limited to these applications and the uses described herein and can be employed in various other applications. The invention is not limited to specific manufacturing techniques or tolerances unless explicitly stated. It encompasses variations in manufacturing methods and material properties as understood by those skilled in the art. Unless specifically defined, all dimensions, proportions, and sizes described herein are by way of example and are not intended to be limiting. The invention contemplates variations in size and proportion suitable for different applications.

[0089] The terminology and phraseology used in this application is for the purpose of descriptionand should not be regarded as limiting. The terms 'comprises', 'comprising', 'includes', 'including', 'having', etc., are inclusive and open-ended and do not exclude additional, unrecited elements or method steps. The singular forms 'a', 'an', and 'the' include plural referents unless the context clearly dictates otherwise. Terms like 'upper', 'lower', 'front', 'back', 'top', 'bottom', etc., are used for descriptive purposes and not necessarily for limitation. These terms denote directions in the drawings to which reference is made and do not limit the orientation of the invention in use. Terms such as 'measuring', 'calculating', 'determining', 'displaying', 'obtaining', etc., refer to actions and processes of the device, system, or computer program, and are understood to be interchangeable and capable of being performed in various sequences or simultaneously. Terms such as 'about', 'approximately', 'substantially', and the like are used herein to represent an inherent degree of uncertainty that can be expected in manufacturing, measurement, and system variation.

[0090] Reference throughout this specification to 'one embodiment' or 'an embodiment' means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the invention.

[0091] The accompanying drawings, which are incorporated herein and form part of the specification, illustrate the embodiments of the invention and, together with the description, further serve to explain the principles of the invention and to enable a person skilled in the art to make and use the invention.

Claims

WHAT IS CLAIMED IS1. A load measuring apparatus comprising: a load receiving part for receiving a load for measurement; a load reacting part for generating one or more reaction forces based on the received load, wherein the load reacting part and the load receiving part are positionally maintained with respect to each other; and one or more force acting members connected to the load receiving part and the load reacting part, each force acting member being replaceable and comprising corresponding two pivot portions, each pivot portion being substantially rigid in a load measuring axis corresponding to each said force acting member, each pivot portion further configured to pivot each said force acting member about a pivot point via elastic deformation in response to a pivoting force received in an axis different from the corresponding load measuring axis, each said force acting member configured to receive in the load measuring axis, via the corresponding two pivot portions, a corresponding applied force and a corresponding reaction force of the one or more reaction forces, the corresponding applied force received from the load receiving part and based on the load, the corresponding reaction force received from the load reacting part and opposite to and based on the corresponding applied force, each said force acting member further comprising a corresponding load measuring component for measuring the corresponding reaction force.

2. The load measuring apparatus of claim 1, wherein each force acting member is individually manufactured.

3. The load measuring apparatus of claim 1, wherein: the one or more force acting members is two or more force acting members.

4. The load measuring apparatus of claim 1, wherein: the one or more force acting members is six force acting members.

5. The load measuring apparatus of claim 1, wherein each force acting member comprises a corresponding pivoting member and a corresponding connecting member, the corresponding pivoting member comprising the corresponding two pivot portions, the corresponding load measuring axis being associated with the corresponding pivoting member, the corresponding pivoting member configured to receive in the load measuring axis, via the corresponding two pivot portions, the corresponding applied force and the corresponding reaction force, the corresponding connecting member connecting the corresponding pivoting member to one of the load receiving part and the load reacting part.

6. The load measuring apparatus of claim 5, wherein one of the corresponding pivoting member and corresponding connecting member comprises the corresponding load measuring component, the corresponding load measuring component being a single axis load cell.

7. The load measuring apparatus of claim 5, wherein each of the corresponding pivoting member and the corresponding connecting member is replaceable.

8. The load measuring apparatus of claim 5, wherein each of the corresponding pivoting member and the corresponding connecting member is individually manufactured.

9. A method of measuring a load, the method comprising: receiving, by a load measuring apparatus at a load receiving part, the load for measurement, the load measuring apparatus comprising: the load receiving part, a load reacting part for generating one or more reaction forces based on the received load, wherein the load reacting part and the load receiving part are positionally maintained with respect to each other; and one or more force acting members connected to the load receiving part and the load reacting part, each force acting member being replaceable and comprising corresponding two pivot portions, each pivot portion being substantially rigid in a load measuring axis corresponding to each said force acting member, each pivot portion further configured to pivot each said force acting member about a pivot point via elastic deformation in responseto a pivoting force received in an axis different from the corresponding load measuring axis, each said force acting member configured to receive in the load measuring axis, via the corresponding two pivot portions, a corresponding applied force and a corresponding reaction force of the one or more reaction forces, the corresponding applied force received from the load receiving part and based on the load, the corresponding reaction force received from the load reacting part and opposite to and based on the corresponding applied force, each said force acting member further comprising a corresponding load measuring component for measuring the corresponding reaction force; and measuring, by the load measuring apparatus, the received load.

10. The method of claim 9 further comprising: measuring, by the load measuring apparatus, the one or more reaction forces, wherein the received load is measured based on the measured one or more reaction forces.

11. The method of claim 9, wherein each force acting member is individually manufactured.

12. The method of claim 9, wherein: the one or more force acting members is two or more force acting members.

13. The method of claim 9, wherein the one or more force acting members is six force acting members.

14. The method of claim 9, wherein each force acting member further comprises a corresponding pivoting member and a corresponding connecting member, the corresponding pivoting member comprising the corresponding two pivot portions, each pivot portion configured to pivot the corresponding pivoting member at the pivot point via elastic deformation in response to the pivoting force, the corresponding load measuring axis being associated with the corresponding pivoting member, the corresponding pivoting member configured to receive in the load measuring axis, via the corresponding two pivot portions, the corresponding applied force and the corresponding reaction force, the correspondingconnecting member connecting the corresponding pivoting member to one of the load receiving part and the load reacting part.

15. The method of claim 14, wherein one of the corresponding pivoting member and corresponding connecting member comprises the corresponding load measuring component, the corresponding load measuring component being a single axis load cell.

16. The method of claim 14, wherein each of the corresponding pivoting member and the corresponding connecting member is replaceable.

17. The method of claim 14, wherein each of the corresponding pivoting member and the corresponding connecting member is individually manufactured.

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