Surface roughness detection method and detection device

Abstract

The invention provides a surface roughness detection method and device, and the method comprises the following steps: a line laser emission module emits line laser at a preset position, the line laser irradiates a detected surface, and the detected surface forms reflected light; the linear laser receiving module focuses reflected light onto a linear array photosensitive element through an imaging lens, the position of a laser line on the linear array photosensitive element generates displacement along with the change of the height of the measured surface, and the displacement of each sampling point of the laser line forms a measurement data set; and the data processing module adopts a least square method to fit a measurement data set to obtain a fitting curve according to a data set with height difference formed by the displacement, the height deviation of each sampling point relative to the fitting curve is calculated, and the distance between the maximum height deviation value in the measurement data set and the fitting curve is the surface roughness. The method can rapidly and accurately measure the roughness of the surface to be measured, and is especially suitable for automatic measurement in an explosion-proof area.

Description

Technical Field

[0001] This invention relates to the field of surface roughness detection technology, and more specifically, to a surface roughness detection method and detection device. Background Technology

[0002] In aircraft manufacturing, the surface quality of composite materials directly affects their performance and service life. Especially after surface polishing, roughness is a crucial indicator for evaluating surface performance. Traditional roughness testing methods typically rely on contact-based equipment, which suffers from low measurement efficiency and difficulty in adapting to automated testing. Furthermore, contact-based equipment cannot be used immediately after spraying or polishing, resulting in low testing efficiency, and most existing equipment cannot operate in explosion-proof environments. Summary of the Invention

[0003] (a) Technical problems to be solved The technical problem to be solved by this invention is that traditional contact equipment cannot standby in an explosion-proof grinding environment and has low roughness detection efficiency.

[0004] (II) Technical Solution To achieve the above objectives, the technical solution adopted by the present invention is as follows: In a first aspect, the present invention provides a surface roughness detection method, comprising the following steps: The line laser emitting module is located at a preset position and emits a line laser with a known divergence angle to illuminate the surface being measured. The surface being measured reflects the line laser to form reflected light. The line laser receiving module focuses the reflected light onto the linear array photosensitive element through an imaging lens. The position of the laser line on the linear array photosensitive element is displaced as the height of the measured surface changes. Each sampling point on the laser line is used to construct a measurement dataset. The data processing module calculates the height difference of the corresponding sampling points on the measured surface based on the displacement, and uses the least squares method to fit the measurement dataset to obtain the fitting curve. It calculates the height deviation of each sampling point relative to the fitting curve, and the distance between the maximum height deviation value in the measurement dataset and the fitting curve is the surface roughness.

[0005] Preferably, the height difference is calculated by the following formula: in, Let be the height difference of the i-th sampling point, xi be the lateral coordinate of the i-th sampling point along the laser measurement line, B be the baseline distance between the line laser emitting module and the line laser receiving module, f be the focal length of the imaging lens, and s be the pixel size. Let u be the pixel coordinates of the corresponding position of each point on the reference curve on the receiver imaging surface. iThe pixel coordinates of the reflected light on the imaging surface of the receiver.

[0006] Preferably, the height deviation d of each sampling point relative to the fitted curve i Calculated by the following formula: in, z is a function that fits the curve. i Let be the height difference of the i-th sampling point.

[0007] Secondly, the present invention also provides a surface roughness detection device, including a housing, a line laser emitting module, a line laser receiving module, and a data processing module. The line laser emitting module and the line laser receiving module are both disposed within the housing. The line laser receiving module includes an imaging lens and a linear array photosensitive element arranged sequentially along the optical path. The line laser emitting module is used to emit a line laser with a known divergence angle, and the line laser receiving module is used to focus the reflected light formed by the reflection of the line laser onto the linear array photosensitive element through the imaging lens.

[0008] Preferably, the angle between the axis of the line laser emitting module and the axis of the line laser receiving module is an acute angle.

[0009] Preferably, the system further includes a cylinder and a lens cover. The cylinder is mounted on the housing, and the output end of the cylinder is connected to the lens cover. The cylinder can drive the lens cover to move so that the lens cover blocks / detaches from the line laser emitting module and the line laser receiving module.

[0010] Preferably, it further includes a power module, a communication and power transmission interface, and a transmission module. The power module and the transmission module are both disposed within the housing. The communication and power transmission interface is used to electrically connect the transmission module and the data processing module. The power module is electrically connected to the transmission module, the line laser emitting module, and the line laser receiving module.

[0011] (III) Beneficial Effects The above-described technical solution of the present invention has at least the following advantages: The surface roughness detection device provided by this invention can quickly and accurately measure the surface roughness of aircraft, and is particularly suitable for automated measurement in explosion-proof areas. This invention employs non-contact laser measurement technology, avoiding surface damage that may be caused by contact detection. The measurement range of this invention can be increased by changing the power and width of the laser emitter and the detection range of the infrared detector. Attached Figure Description

[0012] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0013] Figure 1 This is one of the structural schematic diagrams of the surface roughness detection device provided in the embodiments of the present invention.

[0014] Figure 2 This is the second schematic diagram of the surface roughness detection device provided in the embodiment of the present invention.

[0015] Figure 3 This is a schematic diagram illustrating the implementation principle of the surface roughness detection device provided in this embodiment of the invention.

[0016] The labels for the attached figures are as follows: 1. Housing; 2. Line laser emitting module; 3. Line laser receiving module; 4. Line laser; 5. Reflected light; 6. Cylinder; 7. Lens cover; 8. Communication and power transmission interface; 10. Surface under test. Detailed Implementation

[0017] To make the technical problems to be solved, the technical solutions, and the beneficial effects of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present invention and are not intended to limit the present invention.

[0018] It should be noted that when a component is referred to as "fixed to" or "set on" another component, it can be located directly on or indirectly on the other component. When a component is referred to as "connected to" another component, it can be directly or indirectly connected to the other component.

[0019] It should be understood that the terms "length", "width", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing the present invention, and do not indicate that the device or element must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention.

[0020] The specific implementation of the present invention will be described in more detail below with reference to specific embodiments: like Figure 1 , Figure 2 and Figure 3As shown, this embodiment of the invention provides a surface roughness detection device, including a housing 1, a line laser emitting module 2, a line laser receiving module 3, and a data processing module (not shown). The line laser emitting module 2 and the line laser receiving module 3 are both housed within the housing 1. The line laser receiving module 2 includes an imaging lens and a linear array photosensitive element arranged sequentially along the optical path. The line laser emitting module 2 emits a line laser 4 with a known divergence angle. The line laser receiving module 2 focuses the reflected light 5 formed by the reflection of the line laser 4 onto the linear array photosensitive element through the imaging lens. Specifically, the housing 1 is a sealed housing, specifically an explosion-proof housing, which effectively isolates the internal components from the external space, providing explosion-proof protection. It can standby in a grinding environment, ensuring the safety of the equipment in an explosion-proof environment. The line laser emitting module 2 emits a line laser beam to irradiate the surface to be measured. The line laser emitting module 2 uses a high-precision laser source to ensure the stability and directionality of the laser beam. The line laser receiving module 3 receives the reflected light 5 and detects the fluctuation data caused by surface roughness.

[0021] In one embodiment, the angle between the axis of the line laser emitting module 2 and the axis of the line laser receiving module 3 is an acute angle.

[0022] In one embodiment, a cylinder 6 and a lens cover 7 are also included. The cylinder 6 is mounted on the housing 1, and its output end is connected to the lens cover 7. The cylinder 6 can drive the lens cover 7 to move, thereby blocking / detaching the lens cover 7 from the line laser emitting module 2 and the line laser receiving module 3. The lens cover 7 is opened and closed using the cylinder 6. In standby mode, the lens cover 7 is closed to protect the lens, prevent dust contamination of the equipment surface, and ensure long-term stable operation of the equipment. During operation, the lens cover 7 is opened, and the line laser emitting module 2 and the line laser receiving module 3 are activated.

[0023] In one embodiment, the system further includes a power module (not shown), a communication and power transmission interface 8, and a transmission module (not shown). Both the power module and the transmission module are housed within the housing 1. The communication and power transmission interface 8 electrically connects the transmission module to the data processing module. The power module is electrically connected to the transmission module, the line laser emitting module 2, and the line laser receiving module 3. Specifically, the communication and power transmission interface 8 provides power and data to the line laser emitting module 2, the line laser receiving module 3, and the transmission module. The power module provides power to the device. Further, the data processing module, located in the host computer, receives the fluctuation data sent from the transmission module and converts the data into surface roughness values ​​using an algorithm.

[0024] The surface roughness detection device provided in this embodiment can be mounted on a mobile device such as a robotic arm to realize the automatic measurement of surface roughness at multiple sampling locations on the surface to be tested.

[0025] The surface roughness detection device provided in this embodiment can be used to detect the surface roughness of the coating on parts after painting. The line laser emitting module 2 and the line laser receiving module 3 are not in operation in standby mode, and the cylinder 6 is closed to protect the surfaces of the laser emitting module 2 and the line laser receiving module 3 from grinding dust contamination. After the painting operation is completed, the device starts working, and the cylinder 6 drives the lens cover 7 to open. The line laser emitting module 2 emits a line laser with a known divergence angle, irradiating the surface being measured, forming a light cross-section. Due to the different microscopic height differences on the surface being measured, the reflection position and angle of the line laser on the surface change. The line laser receiving module focuses the reflected light onto the linear array photosensitive element through an imaging lens. The position of the laser line on the photosensitive element shifts with the change in surface height. The line laser receiving module calculates the corresponding height difference based on this displacement, thereby obtaining the height profile data of the surface being measured. The specific method is as follows: This invention also provides a surface roughness detection method, comprising the following steps: S1. The line laser emitting module 2 is located at a preset position and emits a line laser 4 with a known divergence angle, which illuminates the surface 10 under test. The surface 10 under test reflects the line laser 4 to form reflected light 5. Figure 3 In the illustrated embodiment, the line laser emitting module emits a linear laser beam with a specific divergence angle. This laser beam is projected onto the surface of the composite material aircraft to be tested, and the laser line deforms due to the surface undulations, forming a "light cross-section" that reflects the surface contour.

[0026] S2, the line laser receiving module 3 focuses the reflected light 5 onto the linear array photosensitive element through an imaging lens. The position of the laser lines on the linear array photosensitive element changes with the height of the measured surface 10, and each sampling point on the laser lines is used to construct a measurement dataset. After the laser shines on the surface, it will be reflected. Due to the microscopic unevenness (i.e., roughness) of the measured surface, the angle and position of the reflected light will change accordingly. The imaging lens inside the line laser receiving module focuses this changing reflected light signal onto a high-precision linear array photosensitive element (such as a CCD or CMOS sensor).

[0027] S3. The data processing module calculates the height difference of the corresponding sampling points on the measured surface 10 based on the displacement, and uses the least squares method to fit the measurement dataset to obtain a fitting curve. It calculates the height deviation of each sampling point relative to the fitting curve, and the distance between the maximum height deviation in the measurement dataset and the fitting curve is the surface roughness. On the linear photosensitive element, the laser line is no longer a straight line, but a curve that undulates with the surface contour. Each pixel on the photosensitive element generates a corresponding electrical signal based on the received light intensity. The positional offset of the laser line at each pixel directly corresponds to the relative height change of the measured surface at that point. The data processing module initially processes these electrical signals into digitized position coordinate data.

[0028] Specifically, system constants are set in the data processing module: baseline distance B (the distance between the line laser emitting module and the line laser receiving module), imaging lens focal length f, and pixel size s. For an ideally flat reference surface, the pixel coordinates of the reflected light on the receiver are denoted as u. When the surface has a height variation, the actually measured pixel coordinates are u. i Then, the height value z of the i-th measurement point on the surface. i The height difference is calculated using the following formula: in, Let be the height difference of the i-th sampling point, xi be the lateral coordinate of the i-th sampling point along the laser measurement line, B be the baseline distance between the line laser emitting module and the line laser receiving module, f be the focal length of the imaging lens, and s be the pixel size. Let u be the pixel coordinates of the corresponding position of each point on the reference curve on the receiver imaging surface. i The pixel coordinates of the reflected light on the imaging surface of the receiver.

[0029] Using the above formula, a set of discrete data points (measurement dataset) representing the surface profile can be obtained {(x i ,z i )}, where x i It is the horizontal position, z i It is the height value.

[0030] To evaluate roughness, it is necessary to eliminate the influence of the macroscopic shape of the part. Therefore, for the obtained height data {(x i ,z i The least squares method is used to fit a baseline curve z that best represents the overall trend of the contour segment. fit (x i ).

[0031] The height deviation d of each sampling point relative to the fitted curve i Calculated by the following formula: in, z is a function that fits the curve. i Let be the height difference of the i-th sampling point.

[0032] The surface roughness is obtained by finding the distance between the maximum deviation value in the measurement data and the fitted curve. for This R a The value quantitatively reflects the maximum microscopic undulation of the surface of the measured area, thus completing the final conversion from optical signal to quantitative surface quality index.

[0033] This invention enables high-speed, high-precision, non-contact measurement of surface profiles. Finally, a data processing algorithm based on the least squares method accurately converts the profile data into quantifiable roughness parameters. This method significantly improves the automation, efficiency, and safety of aircraft surface quality inspection.

[0034] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for detecting surface roughness, characterized in that, Includes the following steps: The line laser emitting module is located at a preset position and emits a line laser with a known divergence angle to illuminate the surface being measured. The surface being measured reflects the line laser to form reflected light. The line laser receiving module focuses the reflected light onto the linear array photosensitive element through an imaging lens. The position of the laser line on the linear array photosensitive element is displaced as the height of the measured surface changes. Each sampling point on the laser line is used to construct a measurement dataset. The data processing module calculates the height difference of the corresponding sampling points on the measured surface based on the displacement, and uses the least squares method to fit the measurement dataset to obtain the fitting curve. It calculates the height deviation of each sampling point relative to the fitting curve, and the distance between the maximum height deviation value in the measurement dataset and the fitting curve is the surface roughness.

2. The surface roughness detection method as described in claim 1, characterized in that, The height difference is calculated using the following formula: in, Let be the height difference of the i-th sampling point, xi be the lateral coordinate of the i-th sampling point along the laser measurement line, B be the baseline distance between the line laser emitting module and the line laser receiving module, f be the focal length of the imaging lens, and s be the pixel size. Let u be the pixel coordinates of the corresponding position of each point on the reference curve on the receiver imaging surface. i The pixel coordinates of the reflected light on the imaging surface of the receiver.

3. The surface roughness detection method as described in claim 2, characterized in that, The height deviation d of each sampling point relative to the fitted curve i Calculated by the following formula: in, z is a function that fits the curve. i Let be the height difference of the i-th sampling point.

4. A surface roughness detection device, characterized in that, For implementing the surface roughness detection method as described in any one of claims 1-3, the surface roughness detection device includes a housing, a line laser emitting module, a line laser receiving module, and a data processing module. The line laser emitting module and the line laser receiving module are both disposed within the housing. The line laser receiving module includes an imaging lens and a linear array photosensitive element arranged sequentially along the optical path. The line laser emitting module is used to emit a line laser with a known divergence angle, and the line laser receiving module is used to focus the reflected light formed by the reflection of the line laser onto the linear array photosensitive element through the imaging lens.

5. The surface roughness detection device as described in claim 4, characterized in that, The angle between the axis of the line laser emitting module and the axis of the line laser receiving module is an acute angle.

6. The surface roughness detection device as described in claim 4, characterized in that, It also includes a cylinder and a lens cover. The cylinder is mounted on the housing, and the output end of the cylinder is connected to the lens cover. The cylinder can drive the lens cover to move so that the lens cover blocks / detaches from the line laser emitting module and the line laser receiving module.

7. The surface roughness detection device as described in claim 4, characterized in that, It also includes a power module, a communication and power transmission interface, and a transmission module. The power module and the transmission module are both located inside the housing. The communication and power transmission interface is used to electrically connect the transmission module and the data processing module. The power module is electrically connected to the transmission module, the line laser emitting module, and the line laser receiving module.

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