Stress detection device and control system thereof

Abstract

The present application relates to shear stress detection technical field, especially to a kind of stress detection device, comprising: first mechanical arm, second mechanical arm, detection component and power component, its first mechanical arm and second mechanical arm are respectively with same rotational speed along opposite rotating directions movement, to the part to be measured is applied a pair of equal, opposite force moment, to twist the part to be measured;Detection component is used to detect the torque generated by the part to be measured twisted by first mechanical arm and second mechanical arm.This application is by first mechanical arm and second mechanical arm with same rotational speed, opposite direction to part exert torque load, while with the flexible detection band and the strain matrix on it that adhere to the surface of part, real-time acquisition and processing the multidimensional torsional stress generated by part surface in the process of twisting, realize the directional, real-time detection of torsional stress.

Description

Technical Field

[0001] This invention relates to the field of shear stress detection technology, and in particular to a stress detection device and its control system. Background Technology

[0002] In many fields such as modern machinery, aerospace, and construction, the use of automated methods such as robotic arms to detect stress in parts has become a routine practice. Parts often bear loads during service, and stress directly reflects the material's strength, stiffness, and lifespan. By accurately detecting stress, the structural strength and safety of parts can be assessed, ensuring that their design meets operating requirements and preventing accidents caused by shear failure.

[0003] Currently, a commonly used method for detecting residual stress using robotic arms is disclosed in Chinese Patent Application Publication No. CN119104193A, which describes a drilling residual stress detection method based on a six-degree-of-freedom robotic arm. This method aims to solve the problems of low accuracy, complex operation, and limited applicability in existing residual stress detection technologies. The device includes a six-degree-of-freedom robotic arm, a drilling device, strain gauges, a strain meter, and a control system. The six-degree-of-freedom robotic arm can precisely position and move in three-dimensional space, ensuring the accuracy of the drilling position and angle. The drilling device achieves automated drilling through the control system. The strain gauges measure strain changes in real time during and after drilling, and the strain meter collects strain data and analyzes it through a computer processing system. The innovation of this invention lies in combining a six-degree-of-freedom robotic arm, the blind hole method, and strain gauge technology to achieve high-precision, automated residual stress detection on complex curved surfaces, significantly improving detection efficiency and data accuracy. This device is widely applicable to various fields.

[0004] However, the above-mentioned device has the following problem: it can only detect the residual stress of the part under test caused by drilling in real time through the robotic arm, and it is difficult to apply it to the detection of the torsional stress of the part under test. Summary of the Invention

[0005] Therefore, the present invention provides a stress detection device and its control system to overcome the limitations of the prior art, which can only detect the residual stress generated by drilling of the part under test in real time through a robotic arm, and is difficult to apply to the detection of torsional stress of the part under test.

[0006] To achieve the above objectives, the present invention provides a stress detection device, comprising: a first robotic arm, a second robotic arm, a detection component, and a power component, wherein: both the first robotic arm and the second robotic arm are rotatably connected to the detection component; The first robotic arm and the second robotic arm move at the same rotation speed in opposite directions to apply a pair of torques of equal magnitude and opposite direction to the part to be tested, so as to twist the part to be tested; The detection component has a hollow structure for placing the part to be tested inside, and for detecting the torque generated by the twisting of the part to be tested by the first robotic arm and the second robotic arm.

[0007] The first robotic arm and the second robotic arm are provided with a pair of parallel and identical grippers at their ends to fix the part to be tested.

[0008] The central axis of the two grippers coincides with the central axis of the detection component.

[0009] The detection assembly includes: a pair of detection strips arranged in opposite parallel directions, and a plurality of strain units pasted on the inner sides of the two detection strips; Each of the strain units includes a strain matrix formed by three strain gauges and a strain gauge connected thereto.

[0010] The strain matrix consists of three strain gauges spaced at equal angular intervals on the inner surface of the detection band, with the included angle between the central axes of any two adjacent strain gauges being 120°. The three strain gauges contained in the same strain matrix are connected to the same strain gauge.

[0011] A hollow structure is formed between the two detection strips to accommodate the part to be tested. The detection strips are made of flexible material to fit the surface of the part to be tested.

[0012] The first robotic arm and the second robotic arm repeatedly twist the part under test until the detection component completes the detection of the torsional limit of any surface of the part under test.

[0013] The power unit drives the first robotic arm and the second robotic arm to move at the same speed in opposite directions, so that they apply a pair of torques of equal magnitude and opposite direction to the part under test.

[0014] The present invention also provides a stress detection and control system, comprising: A torsion system is used to apply a pair of equal and opposite torques to the part under test in order to torsion the part under test. A detection system, which is connected to the part under test and the torsion system, is used to detect the torque generated by the torsion of the part under test through the torsion system, and to obtain the torsional limit of any surface of the part under test. A power system, which is connected to the torsion system, is used to drive the torsion system to torsion the part under test.

[0015] The part to be tested is clamped and twisted by the torsion system. The stress detection and control system also includes a positioning system, which is used to identify the spatial position of the part to be tested and to guide the torsion system to clamp the part to be tested.

[0016] The beneficial effects of this invention are as follows: This invention provides a stress detection device. Compared to existing technologies that rely solely on robotic arms and are ill-suited for detecting torsional stress, this invention applies a torque load to a part using a first and second robotic arm rotating at the same speed but in opposite directions. Simultaneously, a flexible detection strip attached to the part's surface and its strain matrix directly and in real-time detects the stress on the part under torsional conditions. It collects and processes multidimensional torsional stress generated on the part's surface during torsion, thereby accurately and dynamically acquiring the stress distribution and changes under torsional conditions, achieving directional and real-time detection of torsional stress. This solution fills the technological gap in using robotic arms for targeted detection of torsional stress in parts, significantly expanding the applicability of robotic arms for stress detection.

[0017] Furthermore, this invention drives two robotic arms to move in opposite directions at the same rotational speed via a power component, ensuring that a pair of equal and opposite torques are applied to the part under test, forming a symmetrical torsional condition. This avoids interference from additional bending moments or eccentric loads, ensuring the purity and controllability of torque transmission. It provides a highly stable and repeatable mechanical premise for subsequent torsional stress measurement, thereby enabling directional and real-time detection of torsional stress and expanding the applicability of robotic arms for stress detection.

[0018] Furthermore, the detection component of this invention adopts a hollow structure and utilizes the excellent deformability of flexible materials to adhere to the surface of the part. A strain matrix composed of strain gauges is used to sense surface deformation in real time, improving the sensitivity of torque measurement. The strain gauges are distributed at 120° equidistant angles, enabling comprehensive capture of multi-dimensional strain information. Signal processing via a strain gauge significantly improves the accuracy and reliability of torque detection.

[0019] Furthermore, this invention, by integrating a torsion system, a detection system, and a power system, and optionally adding a positioning system, achieves fully automated control of the entire process from part clamping and positioning, torsional loading, to torque detection. This system can autonomously identify the spatial position of the part, guide the robotic arm to precisely clamp it, and cyclically load it until the torsional limit data is obtained, thus expanding the applicability of the robotic arm for stress detection. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the stress detection device in an embodiment of the present invention; Figure 2This is an enlarged view of the structure in which the first robotic arm, the second robotic arm, and the detection component are connected in an embodiment of the present invention; Figure 3 This is a schematic diagram of the detection component in an embodiment of the present invention; Figure 4 This is a structural block diagram of the stress detection and control system in this invention; Among them, 1 is the first robotic arm, 2 is the second robotic arm, 3 is the detection component, 4 is the power component, 5 is the gripper, 6 is the part to be tested, 7 is the strain gauge, 8 is the detection belt, and 9 is the strain meter. Detailed Implementation

[0021] To make the objectives and advantages of the present invention clearer, the present invention will be further described below with reference to embodiments; it should be understood that the specific embodiments described herein are merely for explaining the present invention and are not intended to limit the present invention.

[0022] Preferred embodiments of the present invention will now be described with reference to the accompanying drawings. Those skilled in the art should understand that these embodiments are merely illustrative of the technical principles of the present invention and are not intended to limit the scope of protection of the present invention.

[0023] It should be noted that in the description of this invention, the terms "upper", "lower", "left", "right", "inner", "outer", etc., which indicate directions or positional relationships, are based on the directions or positional relationships shown in the accompanying drawings. This is only for the convenience of description and is not intended to indicate or imply that the device or element must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation of this invention.

[0024] Furthermore, it should be noted that, in the description of this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0025] To better understand this invention, the terms used in this invention are explained below: Strain gauge: A precision sensor based on the metal strain resistance effect. Its core component is a sensitive grid formed by arranging metal resistance wires or foil grids in a meandering shape on a soft substrate. When it is firmly attached to the surface of an object, it can synchronously convert the microscopic strain (deformation) caused by the force applied to the object into a change in its own resistance value.

[0026] A strain gauge is an electronic instrument used to accurately measure the strain on the surface of an object. Its core function is to detect and amplify the minute resistance changes caused by deformation of a strain gauge attached to the surface of an object. This change is converted into a voltage signal through circuits such as a Wheatstone bridge, and finally the corresponding strain value is calculated and directly displayed.

[0027] Torsional limit: This refers to the maximum torque that a material or part can withstand under pure torsional load before failure (such as fracture or irreversible deformation). It is an indicator of a material's or structure's ability to resist torsional failure.

[0028] Please see Figure 1 As shown, the stress detection device provided by the present invention includes: The system comprises a first robotic arm 1, a second robotic arm 2, a detection component 3, and a power component 4, wherein the first robotic arm 1 and the second robotic arm 2 are rotatably connected to the detection component 3. The first robotic arm 1 and the second robotic arm 2 move at the same speed in opposite directions to apply a pair of torques of equal magnitude and opposite direction to the part to be tested, so as to twist the part to be tested. The detection component 3 is a hollow structure used to place the part to be tested and to detect the torque generated by the twisting of the part by the first robotic arm 1 and the second robotic arm 2.

[0029] Example 1: Torsional limit test of the part under test Step 1: Fix the first and second robotic arms relative to each other on a stable workbench base, ensuring that their workspaces intersect. Rotate the detection component to the first and second robotic arms, ensuring that the grippers at the ends of both robotic arms are in an open and centered position.

[0030] Step 2: The part to be tested is horizontally placed into the hollow cavity of the detection side assembly. The power assembly drives the first and second robotic arms to move towards each other, causing a pair of parallel grippers at their ends to precisely clamp the clamping areas at both ends of the part. The positioning of the grippers relative to the part to be tested can be fed back by laser or vision sensors, allowing for fine adjustment of the robotic arm posture to ensure that the central axes of the two grippers, the central axis of the detection assembly, and the central axis of the part to be tested are completely aligned (as defined in claim 3), thus eliminating off-center loading.

[0031] Step 3: After clamping the part to be tested, the first robotic arm and the second robotic arm (e.g., via a built-in airbag or a micro linear actuator) tighten inward so that the portion of the strain gauge attached to the inner surface of the detection band of the flexible material (such as a high-performance elastic load fabric) in the detection assembly is uniformly and tightly attached to the surface of the part to be tested, ensuring the accuracy of strain transmission.

[0032] Step 4: Start the test program. The power unit drives the first and second robotic arms to rotate at the same preset speed in opposite directions (e.g., the first robotic arm rotates clockwise and the second robotic arm rotates counterclockwise).

[0033] Step 5: Within the detection assembly, three strain gauges at 120° intervals in each matrix sense the multidimensional strain on the part surface in real time and transmit the signals to the corresponding strain gauges. The strain gauges amplify and condition the acquired multi-channel strain signals and simultaneously upload them to the data processing system via a data acquisition card. The data processing system calculates and plots the torque-torsion angle curve and the strain field distribution map on the part surface in real time. The data processing system monitors the torque-torsion angle curve in real time. When the curve reaches its maximum point, the torque value at that moment is recorded, which is the torsional limit (ultimate torque) of the part. For ductile materials, the system continues to record the torque decrease until the part fractures; for brittle materials, the ultimate torque point is usually the fracture point, thus determining the torsional limit of the surface of the tested part.

[0034] Step 6: Repeat the above steps to complete the test of the torsional limit of any surface of the part to be tested.

[0035] The stress detection device provided by this invention, compared to existing technologies that rely solely on robotic arms and are ill-suited for detecting torsional stress, utilizes a first and second robotic arm that applies a torque load to a part at the same rotation speed but in opposite directions. Simultaneously, a flexible detection strip attached to the part's surface and its strain matrix directly and in real-time detect the stress on the part under torsional conditions. This allows for real-time acquisition and processing of multidimensional torsional stress generated on the part's surface during torsion, thereby accurately and dynamically obtaining the stress distribution and changes under torsional conditions, achieving directional and real-time detection of torsional stress. This solution fills the technological gap in using robotic arms for targeted detection of torsional stress in parts, significantly expanding the applicability of robotic arms for stress detection.

[0036] Please see Figure 2 As shown, the end of the first robotic arm and the end of the second robotic arm are provided with a pair of parallel and identical grippers 5, which are used to fix the part 6 to be tested.

[0037] This invention drives two robotic arms to move in opposite directions at the same rotational speed via a power component, ensuring that a pair of equal and opposite torques are applied to the part under test, forming a symmetrical torsional condition. This avoids interference from additional bending moments or eccentric loads, guaranteeing the purity and controllability of torque transmission. It provides a highly stable and repeatable mechanical basis for subsequent torsional stress measurement, thereby enabling directional and real-time detection of torsional stress and expanding the applicability of robotic arms for stress detection.

[0038] Please continue reading. Figure 2The central axis of the two grab hooks 5 coincides with the central axis of the detection component 3.

[0039] Please see Figure 3 The detection assembly includes: a pair of parallel detection strips 8 facing each other, and a plurality of strain units pasted on the inner sides of the two detection strips; Each strain unit includes a strain matrix formed by three strain gauges 7 and a strain gauge 9 connected thereto.

[0040] Please continue reading. Figure 3 As shown, the strain matrix consists of three strain gauges 7 spaced at equal angles on the inner surface of the detection zone, with the included angle between the central axes of any two adjacent strain gauges 7 being 120°. Among them, the three strain gauges 7 contained in the same strain matrix are connected to the same strain gauge 9.

[0041] In the process, the inner surface of the test strip is cleaned; then a specialized strain adhesive, such as cyanoacrylate, is applied; the strain gauges are precisely fitted together at a pre-interlocked 120° angle to form a strain matrix, and gently rolled to remove air bubbles; then uniform pressure is applied and heated to cure, ensuring bond strength; after curing, electrical testing is performed, and finally a protective layer is applied. This ensures that the strain gauges can transmit the strain signal of the measured surface with high fidelity.

[0042] A hollow structure is formed between the two detection strips to accommodate the part to be tested. The detection strips are made of flexible material to fit the surface of the part to be tested.

[0043] In practice, the aforementioned flexible materials can be made from polymer films, which have high strength, good toughness, low creep, can accurately transmit strain, good kinetic and chemical stability, and electrical insulation.

[0044] It is understandable that the materials used in the above-mentioned flexible materials can be arbitrarily combined with existing technologies according to the specific characteristics of the part under test, such as size, shape, conductivity, and usage conditions, which will not be elaborated here.

[0045] The first and second robotic arms repeatedly twist the part under test until the detection assembly completes the detection of the torsional limit of any surface of the part under test.

[0046] The power unit drives the first and second robotic arms to move at the same speed in opposite directions, so that they apply a pair of torques of equal magnitude and opposite direction to the part to be measured.

[0047] Please see Figure 4 The stress detection and control system provided by the present invention includes: A torsion system is used to apply a pair of equal and opposite torques to the part under test in order to torsion the part under test. The detection system is connected to the part under test and the torsion system to detect the torque generated by the torsion of the part under test through the torsion system and obtain the torsional limit of any surface of the part under test. The power system, which is connected to the torsion system, is used to drive the torsion system to torsion the part under test.

[0048] The part under test is clamped and twisted by a torsion system. The stress detection and control system also includes a positioning system, which is used to identify the spatial position of the part under test and guide the torsion system to clamp the part under test.

[0049] Example 2: Positioning System for the Part Under Test Step 1: Calibrate the positioning system. Use a vision sensor to photograph a calibration board of known dimensions to establish a precise transformation relationship between the robotic arm's base coordinate system and the detection component's coordinate system. Simultaneously, identify and record the image features of the visual feature markers on the gripper at zero point, serving as the benchmark for subsequent calculations.

[0050] Step 2: The part to be tested is placed within a preset working area near the detection component (hollow structure). The vision sensor then scans the working area to collect point cloud data or two-dimensional images of the part.

[0051] Step 3: The positioning system analyzes the acquired visual data, using algorithms such as edge detection and template matching to identify the contours, key edges, or pre-attached positioning marks of the parts. Based on the calculated precise pose of the part and the current pose of the gripper, the control system performs the following calculations: Target gripping point calculation: Determines the coordinates of the gripped area (such as a shoulder or a specific plane) on the part within the robotic arm's base coordinate system. Obstacle avoidance path planning: Plans the coordinated motion trajectory of the gripper from closure to the target gripping point, ensuring no collisions with parts, detection components, or other equipment during the process.

[0052] Step 4: The calculated motion path and attitude commands are sent to the drive system so that the gripper moves synchronously according to the commands, causing its end gripper to move along the planned path to both sides of the part, achieving precise and centered clamping of the part. The positioning system ensures through real-time feedback that after clamping, the central axis of the part, gripper, and detection component coincides.

[0053] This invention integrates a torsion system, a detection system, and a power system, with an optional positioning system, to achieve fully automated control of the entire process from part clamping and positioning, torsional loading, to torque detection. The system can autonomously identify the spatial position of the part, guide the robotic arm to precisely clamp it, and cyclically load it until the torsional limit data is obtained, thus expanding the applicability of robotic arms for stress detection.

[0054] The technical solution of the present invention has been described above with reference to the preferred embodiments shown in the accompanying drawings. However, it will be readily understood by those skilled in the art that the scope of protection of the present invention is obviously not limited to these specific embodiments. Without departing from the principles of the present invention, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after these changes or substitutions will all fall within the scope of protection of the present invention.

[0055] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A stress detection device, characterized in that, include: A first robotic arm, a second robotic arm, a detection component, and a power component, wherein: both the first robotic arm and the second robotic arm are rotatably connected to the detection component; The first robotic arm and the second robotic arm move at the same rotation speed in opposite directions to apply a pair of torques of equal magnitude and opposite direction to the part to be tested, so as to twist the part to be tested; The detection component has a hollow structure for placing the part to be tested inside, and for detecting the torque generated by the twisting of the part to be tested by the first robotic arm and the second robotic arm.

2. The stress detection device according to claim 1, characterized in that, The first robotic arm and the second robotic arm are provided with a pair of parallel and identical grippers at their ends to fix the part to be tested.

3. The stress detection device according to claim 2, characterized in that, The central axis of the two grippers coincides with the central axis of the detection component.

4. The stress detection device according to claim 3, characterized in that, The detection assembly includes: a pair of detection strips arranged in opposite parallel directions, and a plurality of strain units pasted on the inner sides of the two detection strips; Each of the strain units includes a strain matrix formed by three strain gauges and a strain gauge connected thereto.

5. The stress detection device according to claim 4, characterized in that, The strain matrix consists of three strain gauges spaced at equal angular intervals on the inner surface of the detection band, with the included angle between the central axes of any two adjacent strain gauges being 120°. The three strain gauges contained in the same strain matrix are connected to the same strain gauge.

6. The stress detection device according to claim 5, characterized in that, A hollow structure is formed between the two detection strips to accommodate the part to be tested. The detection strips are made of flexible material to fit the surface of the part to be tested.

7. The stress detection device according to claim 6, characterized in that, The first robotic arm and the second robotic arm repeatedly twist the part under test until the detection component completes the detection of the torsional limit of any surface of the part under test.

8. The stress detection device according to claim 7, characterized in that, The power unit drives the first robotic arm and the second robotic arm to move at the same speed in opposite directions, so that they apply a pair of torques of equal magnitude and opposite direction to the part under test.

9. A stress detection and control system, characterized in that, include: A torsion system is used to apply a pair of equal and opposite torques to the part under test in order to torsion the part under test. A detection system, which is connected to the part under test and the torsion system, is used to detect the torque generated by the torsion of the part under test through the torsion system, and to obtain the torsional limit of any surface of the part under test. A power system, which is connected to the torsion system, is used to drive the torsion system to torsion the part under test.

10. The stress detection system according to claim 9, characterized in that, include: The part to be tested is clamped and twisted by the torsion system. The stress detection and control system also includes a positioning system, which is used to identify the spatial position of the part to be tested and to guide the torsion system to clamp the part to be tested.

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