CN101470080A - Surface shape image detection system based on structured light projection - Google Patents

Abstract

The invention discloses a surface shape image detection system based on structured light projection. Including detection vehicle body, rear view image acquisition system, front view road condition digital video acquisition system, odometer, patterned structured light emitter and computer. The optical axis is perpendicular to the measured road surface; the forward-looking road condition digital video acquisition system and the patterned structured light emitter are connected to the odometer, and the patterned structured light emitter is arranged at the rear of the detection vehicle body; one end of the odometer is connected to the detection vehicle body The odometer is connected; the computer with the image acquisition card is set in the detection vehicle body and connected with the high-speed CCD camera. The invention is non-contact, can be detected quickly, has high measurable precision, can directly see the image, can mark the measurement data with mileage, has a simple structure, is easy to operate, and can directly give the road surface shape and change value. It can be applied to non-contact measurement of surface structure in other fields.

Description

Surface Shape Image Detection System Based on Structured Light Projection

technical field

The invention relates to a non-contact measurement technology of road surface shape, in particular to a surface shape image detection system based on structured light projection.

Background technique

Roads, especially highway pavement, after running for a period of time, the defects such as rutting, poor flatness and wrong platform are important items in the routine inspection and annual inspection of the road, because when these diseases are serious, not only the vehicle body will be caused Bumpy, uncomfortable, and will accelerate vehicle damage, and even cause traffic accidents, so these disease parameters of expressways have been taken as one of the basic decision-making basis for the timing and method of pavement maintenance in the world. With the advancement of computer technology, photoelectric technology, and high-precision measurement technology, my country has also made great progress in road surface testing instruments and technology. In recent years, some relatively high-speed, non-contact vehicle-mounted detection instruments have been developed, such as lasers, ultrasonic level gauges, and laser road surface elevation meters based on the principle of triangulation ranging. Acceleration sensors and angular velocity sensors are used to correct vehicle body vibrations The measurement error, and the common-beam double-density elevation measurement method using the quadratic difference principle are used to quickly measure the pavement rutting parameters. The above-mentioned device (system) uses a laser sensor or an ultrasonic sensor to obtain the lateral rutting data by means of horizontal equal spacing (minimum 3 points), longitudinal equal spacing sampling or zigzag scanning sampling.

For example, the utility model patent No. 200310106457 discloses a "laser three-dimensional digital road shape instrument", which includes an instrument carrier vehicle, a flatness instrument is arranged on the lower side of the vehicle body, a laser road surface damage condition detector and a laser road surface damage condition detector are arranged at the rear end of the vehicle body. Rutting Profiler. The flatness meter is composed of two common-beam altimeters; the road surface damage detector is composed of a group of equiangularly spaced multi-chip light sources and an area array CCD image detector that illuminate the road surface at a small angle; The illuminating sheet light source is composed of an area array CCD image detector. Among them, the rut data is obtained by "zigzag" scanning sampling method, and the impact caused by the vibration of the vehicle body has not been seen to be solved. As a result, the measurement accuracy is difficult to guarantee, and it is difficult to achieve an accuracy of less than a millimeter.

Contents of the invention

The purpose of the present invention is to provide a simple structure, non-contact, fast detection, high density, digitization and visually visible image, which can reach millimeter-level accuracy, and the measurement data is marked with mileage to correctly evaluate the road surface and guide maintenance. The surface shape image detection system projected by structured light can be applied to the detection and measurement of various road surface changes such as rutting, flatness, wrong platform, potholes and ponds.

The technical solution to realize the object of the present invention is: a surface shape image detection system based on structured light projection, including the detection vehicle body, characterized in that it also includes a rear-view image acquisition system, a front-view road condition digital video acquisition system, a mileage Meter, patterned structured light emitter and computer, the rear view image acquisition system uses a high-speed CCD camera, which is set on the outer side above the rear of the detection vehicle body, and its optical axis is perpendicular to the measured road surface; the front view road condition digital video acquisition system and patterned The structured light emitters are all connected to the odometer, and the patterned structured light emitter is set at the rear of the detection vehicle body; one end of the odometer is connected to the odometer of the detection vehicle body; the computer with the image acquisition card is set in the detection vehicle body, through The network card is connected with the high-speed CCD camera.

The working principle of the present invention is the principle of structured light distance measurement. Through the active structured light projection of the known mode, the camera is used to passively collect the imaging information of the structured light on the road surface, and the high-performance parallel computer is used to process and analyze the image of the road surface. According to The deformation of the structured light mode, and then use the principle of visual calibration to restore the depth information of the road surface change, and locate the location of the disease. The patterned structured light emitter installed on the car body projects a known pattern of structured light to the road surface. The pattern can be multi-line or grid type, and phase-encoded type. The projected light forms a small angle with the road surface and has a certain The high-speed CCD camera passively collects the imaging information of structured light on the road surface perpendicular to the road surface; the visual calibration method is used to realize the mapping between the image space and the actual measurement space, and the deformed structured light is compared with the structured light formed on the standard template. In contrast, for the deformed structured light image, through preprocessing, grayscale correction, binarization, refinement and calculation of the distance from each point on the line to the lower tangent, and according to the template image calibration to determine what each pixel in the horizontal direction of the image represents The actual distance system and other steps can get the road surface depth data.

Compared with the prior art, the present invention has the following remarkable advantages: 1. It does not need an acceleration sensor, can effectively eliminate the influence of vehicle body vibration on the flatness measurement, and strictly follow the mileage mark for the flatness data; 2. Simple structure and convenient operation , has the characteristics of continuous measurement, can directly give the road surface shape and change value, overcomes the high price of multi-sensor technology, cannot realize the measurement of the whole lane and is difficult to synchronize and other difficulties; 3. Compared with related patents, the direct measurement method is adopted , the road surface is illuminated by line structured light, and the change of the road surface is directly acquired and detected, which is not affected by factors such as sensor bumps caused by vehicle driving, and has high measurement accuracy, which can reach millimeter-level accuracy.

Description of drawings

FIG. 1 is an overall schematic diagram of a surface shape image detection system based on structured light projection according to the present invention.

Fig. 2 is a schematic diagram of connection of various devices of the present invention.

Fig. 3-Fig. 5 are schematic diagrams of the basic principles of the present invention.

Detailed ways

The basic principle and specific structure of the present invention will be further described in detail below in conjunction with the accompanying drawings.

1, the detection system of the present invention is composed of a detection vehicle body 5, a rear view image acquisition system, a front view road condition digital video acquisition system 7, an odometer 8, a patterned structured light transmitter 2 and a computer 4. The rear view image acquisition system mainly includes a high-speed CCD camera 3, which is directly installed and fixed on the outer side above the tail of the detection vehicle body 5. The optical axis of the high-speed CCD camera 3 is perpendicular to the measured road surface 6; the patterned structured light emitter 2 is installed and fixed in the box body 1 at the rear of the detection vehicle body, 20cm to 30cm away from the ground, and the patterned structured light formed by it and the road surface An acute angle α is formed to illuminate the road surface laterally, and the camera passively collects the imaging information of the structured light on the road surface from directly above it.

2, the high-speed CCD camera 3 of the present invention, the forward-looking digital video acquisition system 7 and the patterned structured light transmitter 2 are all driven by the odometer 8, and one end of the odometer is connected to the odometer of the detection vehicle body 5. The computer 4 with the image acquisition card is connected with the high-speed CCD camera 3 through the network card, and the image signals collected are directly converted into digital network signals for transmission.

The patterned structured light emitter [2] projects structured light of a known pattern to the road surface. The pattern can be multi-line or grid type, and phase-encoded. The projected light forms a small angle with the road surface and has a certain High-speed CCD camera 3 passively collects the imaging information of structured light on the road surface perpendicular to the road surface; uses the visual calibration method to realize the mapping between the image space and the actual measurement space, and compares the deformed structured light with the structured light formed on the standard template For comparison, for the deformed structured light image, the distance between each point on the line and the lower tangent is calculated through preprocessing, grayscale correction, binarization, thinning, and the distance between each pixel point in the horizontal direction of the image is determined according to the template image calibration. The road surface depth data can be obtained through steps such as the actual distance system represented.

Referring to Fig. 3-Fig. 5, the basic principle of the present invention is to utilize the linear propagation characteristic of light: when a beam of light shoots to the ground with a fixed height and inclination angle, if the ground is horizontal, a straight line will be observed from the direction perpendicular to the ground; When the surface is not horizontal, the protruding part will hinder the light from advancing, and the concave part will make the light go farther, so that when observed from the vertical direction of the ground, it will be found that it is a curve, the curve of the protruding part is close to the light source and the curve of the concave part is away from the light source . The distance that can be analyzed is directly related to the degree of protrusion (depression), and the actual measurement value of its variation can be obtained through visual calibration technology. According to this principle, the concave-convex structure of the road surface can be obtained by analyzing the curved shape in the vertical direction of the ground. Figure 1 simulates the trajectory of a light. In the figure, the x-axis represents the measured road surface, the z-axis represents the shooting direction of the camera, and the structured light rays are emitted from point o. Figure a shows the situation when the road surface is level. It can be seen that when the ground is level, the irradiation point is at point c. Figure b shows the bump on the road surface. Due to the obstruction of the bump, the irradiation point of the light is located at point a. The distance between points a and c is the distance between points b and c from the observation angle perpendicular to the ground. The angle is predetermined, so the bump height ab can be calculated from this angle. Figure c shows the situation where there is a depression on the road surface. Similarly, the depression depth ab can be obtained.

Claims (4)

1. A surface shape image detection system based on structured light projection, including the detection vehicle body [5], characterized in that it also includes a rear view image acquisition system, a front view road condition digital video acquisition system [7], an odometer [ 8], a patterned structured light transmitter [2] and a computer [4], the rear view image acquisition system uses a high-speed CCD camera [3], which is set on the outer side above the tail of the detection vehicle body [5], and its optical axis is perpendicular to the Measuring the road surface [6]; the forward-looking digital video acquisition system for road conditions [7] and the patterned structured light transmitter [2] are connected to the odometer [8], and the patterned structured light transmitter [2] is set on the detection vehicle body [ 5] rear portion; one end of the odometer [8] is connected to the odometer of the detection vehicle body [5]; the computer [4] with image acquisition card is arranged in the detection vehicle body [5] and is connected with the high-speed CCD camera. 2. The surface shape image detection system based on structured light projection according to claim 1, characterized in that the signal of the odometer [8] triggers the structured light emitter [2], the high-speed CCD camera [3] and the forward-looking road condition digital Video acquisition system [7]. 3. The surface shape image detection system based on structured light projection according to claim 1 or 2, characterized in that the computer is connected to a high-speed CCD camera through a network card. 4. The surface shape image detection system based on structured light projection according to claim 1 or 2, characterized in that the patterned structured light emitter [2] is arranged in the box at the rear of the detection vehicle body [5] [1] inside.

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