Methods for color and gloss detection based on machine vision and laser ranging

Abstract

This invention relates to a method for color and gloss detection based on machine vision and laser ranging, comprising the following steps: S1, starting material loading, after which a robot arm picks up the material and moves it to a photographing position; S2, the vision system performs photographic positioning, recording the coordinates of a certain feature of a standard product within the camera; S3, the robot arm moves the product to a ranging position, detecting the color / gloss coordinates of a certain location on the standard product, and recording the displacement sensor reading; S4, the robot arm picks up a new product and moves it to the photographing position to take a picture, obtaining the coordinates of the new product within the camera; S5, the robot arm moves the product to the displacement sensor measurement position, recording the displacement sensor reading; S6, controlling the robot arm to move to the new coordinates to detect the product's color / gloss. This invention has high positioning accuracy, ensuring the accuracy of the equipment's detection and providing good stability, thus better meeting modern industrial needs.

Description

Technical Field

[0001] This invention relates to the field of visual inspection technology, and in particular to a method for color and gloss detection based on machine vision and laser ranging. Background Technology

[0002] In modern manufacturing and quality control, color and gloss testing are crucial steps in ensuring that product appearance meets standards.

[0003] In existing testing equipment, product positioning is generally achieved using a cylinder clamping method. However, this cylinder-based positioning method introduces a ±0.1mm positioning error, causing the measurement point to deviate by ±0.1mm.

[0004] Furthermore, both color and gloss measurements involve emitting white light and then calculating the characteristics of the reflected light to determine the specific value. Meanwhile, automated inspection equipment often employs non-contact measurement, thus requiring a very high working distance from the sensor. Traditional automated inspection equipment, however, uses sensors that move to a fixed location, and coupled with the preceding cylinder positioning error, this easily leads to inconsistent and fluctuating distances between the sensor and the detection point. Summary of the Invention

[0005] The technical problem to be solved by this invention is to provide a method for color and gloss detection based on machine vision and laser ranging, thereby solving the problem of inaccurate color and gloss position of product surfaces in traditional or manual detection methods.

[0006] The technical solution adopted by this invention to solve its technical problem is: a method for color and gloss detection based on machine vision and laser ranging, comprising the following steps: S1. Start loading materials. After the robotic arm picks up the material, it moves the product to the photo-taking position. S2. The vision system performs image positioning and records the coordinates (Xstd, Ystd) of a certain feature of a standard product within the camera. S3. The robotic arm moves the product to the ranging position, detects the coordinates (X,Y,Z,U,V,W) of the color / gloss at a certain position of the standard product, and records the displacement sensor reading Zstd. S4. The robotic arm picks up the new product and moves it to the camera position to take a picture, obtaining the coordinates (Xc, Yc) of the new product in the camera. S5. The robotic arm moves the product to the position measured by the displacement sensor and records the displacement sensor reading Zc. S6. Control the robotic arm to move to new coordinates (X+Xstd-Xc, Y+Ystd-Yc, Z+Zstd-Zc, U, V, W) to detect the product color / gloss.

[0007] Furthermore, in step S2 of the present invention, the coordinate relationship between the 2D camera and the robotic arm is associated using a nine-point calibration method.

[0008] Furthermore, the vision system in step S2 of the present invention includes a camera lens, a ring light source, and a backlight source; the distance between the camera lens and the product under test is 130±5 mm, the camera lens and the ring light source are positioned above the product under test, the backlight source is positioned below the product under test, and the distance between the backlight source and the product under test is 500±50 mm.

[0009] The beneficial effect of this invention is that it solves the defects existing in the prior art. Using machine vision technology, the points that need to be inspected on a product can be located very accurately, thus solving the problems of errors and inaccurate measurement points caused by traditional mechanical positioning. Before using sensor measurement, the distance to the detection point is measured by a laser displacement sensor. The value returned by the displacement sensor is used to correct the distance between the sensor and the detection point, thereby ensuring the correct working distance of the sensor. This method mainly introduces machine vision technology and laser ranging technology, which has higher positioning accuracy than the previous use of mechanical positioning (cylinder positioning), ensuring the accuracy of equipment detection and giving the equipment good stability, better meeting the needs of modern industry. Attached Figure Description

[0010] Figure 1 This is a flowchart illustrating the present invention. Detailed Implementation

[0011] The present invention will now be described in further detail with reference to the accompanying drawings and preferred embodiments. These drawings are simplified schematic diagrams, illustrating only the basic structure of the invention, and therefore only show the components relevant to the invention.

[0012] like Figure 1 This illustrates a method for color and gloss detection based on machine vision and laser ranging; Machine vision technology mainly includes image processing, mechanical engineering technology, control, electric light source illumination, optical imaging, sensors, analog and digital video technology, and computer hardware and software technology (image enhancement and analysis algorithms, image cards, I / O cards, etc.).

[0013] The hardware includes a CCD, lens, light source, image acquisition card (network card), and PC; the software mainly focuses on image processing.

[0014] The light source used in this embodiment includes a ring light source and a backlight source. The distance between the camera lens and the product under test is 130±5 mm. The camera lens and the ring light source are positioned above the product under test, and the backlight source is positioned below the product under test. The distance between the backlight source and the product under test is 500±50 mm.

[0015] Image processing software used includes commercially available options such as Halcon, VisionPro, and Sherlock, as well as open-source options like OpenCV. These hardware components are then assembled to capture images of the product's fixed features.

[0016] Before inspection, it is necessary to find the relationship between the world coordinate system and the image coordinate system. This relationship can be used to calculate the world coordinate system of the product from the image, and then instruct the actuator to move to the corresponding position, thereby achieving machine vision-guided precise positioning of the product to be inspected.

[0017] This embodiment also utilizes laser displacement ranging technology to correct the distance between the product detection surface and the sensor, ensuring the sensor operates at the correct working distance and that the sensor's measurement data is highly reliable. Before each sensor measurement, the distance to the product surface (the location to be detected) is measured using a laser. Based on the measured distance, the actuator's movement is corrected in real time. Therefore, it is possible to ensure that the distance between the product detection surface and the sensor is stable and accurate.

[0018] The specific steps are as follows: 1. Use a nine-point calibration method to establish the coordinate relationship between the 2D camera and the robot (this relationship is in the 2D plane. The robot's coordinates are in 3D, and a laser displacement sensor is used to compensate for the other direction. An alternative technique here is to use a 3D camera to calibrate the spatial transformation relationship between the camera and the robot).

[0019] 2. Record the coordinates (Xstd, Ystd) of a certain feature of a standard product within the camera, teach the robot arm to detect the coordinates (X, Y, Z, U, V, W) of the color / gloss of a certain position on the standard product, and record the displacement sensor reading Zstd.

[0020] 3. After the new product (the product to be tested later) is picked up by the robotic arm, it is moved to the camera position to take a picture, and the coordinates (Xc, Yc) of the new product in the camera are obtained. Then it is moved to the displacement sensor measurement position, and the displacement sensor reading Zc is obtained.

[0021] 4. Control the robotic arm to move to new coordinates (X+Xstd-Xc, Y+Ystd-Yc, Z+Zstd-Zc, U, V, W) to detect the product color / gloss.

[0022] This invention ensures accurate detection of color and gloss at a specific location on a product through the above four steps. In the detection of product color difference and gloss, machine vision is introduced to accurately locate the detection point, and laser displacement ranging technology is introduced to correct the working distance of the sensor. The robot or axis is guided to move to the corresponding position, thereby achieving accurate positioning of the detection point. The detection equipment using this method (for mass production detection) has good correlation with the detection equipment used in the laboratory, ensuring the accuracy of the equipment detection.

[0023] The above description is only a specific embodiment of the present invention. Various examples and illustrations do not constitute a limitation on the substantive content of the present invention. Those skilled in the art can make modifications or variations to the above-described specific embodiments after reading the specification without departing from the substance and scope of the invention.

Claims

1. A method for color and gloss detection based on machine vision and laser ranging, characterized in that: Includes the following steps, S1. Start loading materials. After the robotic arm picks up the material, it moves the product to the photo-taking position. S2. The vision system performs image positioning and records the coordinates (Xstd, Ystd) of a certain feature of a standard product within the camera. S3. The robotic arm moves the product to the ranging position, detects the coordinates (X, Y, Z, U, V, W) of the color / gloss at a certain position of the standard product, and records the displacement sensor reading Zstd. S4. The robotic arm picks up the new product and moves it to the camera position to take a picture, obtaining the coordinates (Xc, Yc) of the new product in the camera. S5. The robotic arm moves the product to the position measured by the displacement sensor and records the displacement sensor reading Zc. S6. Control the robotic arm to move to new coordinates (X+Xstd-Xc, Y+Ystd-Yc, Z+Zstd-Zc, U, V, W) to detect the product color / gloss.

2. The method for color and gloss detection based on machine vision and laser ranging as described in claim 1, characterized in that: In step S2, the coordinate relationship between the 2D camera and the robot arm is associated using a nine-point calibration method.

3. The method for color and gloss detection based on machine vision and laser ranging as described in claim 1, characterized in that: The vision system in step S2 includes a camera lens, a ring light source, and a backlight source; the distance between the camera lens and the product under test is 130±5 mm, the camera lens and the ring light source are positioned above the product under test, the backlight source is positioned below the product under test, and the distance between the backlight source and the product under test is 500±50 mm.

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