CN102288118A - Method for measuring multi-measuring point dynamic displacement by singe camera - Google Patents

Abstract

The invention relates to a method for single-camera multi-measuring point dynamic displacement measurement, which is to fix a mark with a certain shape on the surface of the object to be measured, and use the centroid of the mark as an observation point on the surface of the object to be measured. Use a high-speed camera to take a series of photos of the sign during its movement, and then read and analyze the photos in sequence through a program independently developed on the basis of the LabVIEW software vision and movement module, record the movement track of the sign point, and draw the corresponding displacement at the same time - time curve. By setting a series of different observation points, the precise measurement of the dynamic displacement of multiple measuring points can be realized.

Description

A Method for Measuring Dynamic Displacement with Single Camera and Multiple Measuring Points

technical field

The invention relates to a method for measuring the dynamic displacement of a single camera and multiple measuring points.

Background technique

Existing patents for moving displacement measurement using cameras mainly include the method for measuring the three-dimensional position and attitude of objects with a single camera (application number/patent number: 201010184619) applied by Xue Jianru of Xi’an Jiaotong University and others in 2010, and Zhang Zhengyu’s application in 2009 Multi-camera dynamic photogrammetry method in vibration environment (application number/patent number: 200910305434). These methods have made effective attempts on the camera's dynamic displacement measurement, but none of them can solve the two key issues that the surveyors are most concerned about in engineering applications: accuracy and economy.

Contents of the invention

The purpose of the present invention is to provide a method for measuring dynamic displacement of multiple measuring points with a single camera, which can realize accurate measurement of dynamic displacement of multiple measuring points.

The method for single-camera multi-measuring point dynamic displacement measurement of the present invention is characterized in that it comprises the following steps: Step 1: Fix a mark with a certain shape on the surface of the object to be measured; Step 2: Use the centroid of the mark As an observation point on the surface of the measured object, use a high-speed camera to take a series of photos of the mark during its movement; step 3: use Vision Acquisition software to extract a sample from the high-speed camera, and specify on the sample The method of specifying the length of the straight line segment calculates the ratio coefficient between the pixel size of the sample and the actual size of the fixed marker point, which is used to realize the unit conversion in the whole process of camera measurement; Step 4: Carry out the repeated sampling and analysis process of the dynamic displacement of the observation marker, And record the movement trajectory of the marker points, and draw the corresponding displacement-time curve at the same time.

According to the above-mentioned technical scheme, by setting a series of different observation points, the precise measurement of the dynamic displacement of multiple measuring points can be realized.

The beneficial effect of the invention is that it can improve the accuracy and precision of the measurement results of the dynamic displacement, and has the advantages of easy use, low price and simultaneous measurement of multiple measuring points compared with similar products on the market.

Description of drawings

Fig. 1 is a schematic flow chart of the method of the present invention.

Fig. 2 is a schematic diagram of the system architecture of the embodiment of the present invention.

the

Detailed ways

The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

The method for measuring the dynamic displacement of a single camera with multiple measuring points in this embodiment is characterized in that it comprises the following steps: Step 1: Fix a mark with a certain shape on the surface of the measured object, where the certain shape can be a circle , triangle, quadrilateral or pentagon, etc.; Step 2: Take the centroid of the mark as an observation point on the surface of the measured object, and use a high-speed camera to take a series of photos of the mark in motion; Step 3: Use the NI company The provided Vision Acquisition software extracts a sample from the high-speed camera, and calculates the ratio coefficient between the pixel size of the sample and the actual size of the fixed marker point by specifying the length of a specific straight line segment on the sample, and the ratio coefficient is used for Realize the unit conversion of the whole process of camera measurement; step 4: carry out the repeated sampling and analysis process of the dynamic displacement of the observation mark, record the movement track of the mark point, and draw the corresponding displacement-time curve at the same time. As shown in Figure 1, in the present embodiment, the described repeated sampling analysis process is realized by a while loop of continuous sampling analysis; each loop process includes: first, utilize Vision Acquisition software to read a fixed mark from the camera During the measurement process, attention should be paid to ensure that the boundary of the fixed mark will not exceed the field of view of the camera during the process of moving with the measured object; then, use the "Locate Edges" command provided by LabVIEW software to locate the boundary Boundary analysis and positioning are performed on instant photos, and the centroid coordinates of fixed signs are obtained; finally, the centroid coordinates are used as the real-time position of the measured object, displayed on the computer screen in real time, and input into the system for data storage. The sampling analysis process is repeated until the "STOP" button on the control panel is clicked to end the sampling analysis.

In order to allow those skilled in the art to better understand the present invention, please refer to Fig. 2, which is a schematic diagram of the system architecture of this embodiment. In this embodiment, we use a high-speed camera for image acquisition. As shown in Fig. 2, the high-speed camera 1 It is connected with the wide-angle lens 2 and fixed on the tripod 3. At the same time, it is connected with the computer 4 through the 1394 data connection line 6 and the 1394 data acquisition card 5. Then, the mark 7 is fixed at the observation point on the surface of the measured object 8, and then the dynamic displacement measurement software is used to measure the The real-time dynamic displacement of the sign is collected, analyzed and recorded.

The above descriptions are only preferred embodiments of the present invention, and all equivalent changes and modifications made according to the scope of the patent application of the present invention shall fall within the scope of the present invention. the

Claims (5)

1. the method for the moving displacement measurement of one camera multi-measuring point is characterized in that, may further comprise the steps realization:

Step 1: a certain sign with definite shape is fixed on the testee surface;

Step 2: as the lip-deep observation station of testee, utilize high speed camera to take a series of photos of sign in motion process with the centre of form of this sign;

Step 3: utilize Vision Acquisition software, extract a print from described high speed camera, and by on this print, stipulating the method for particular line segment length, calculate the pixel size of print and the scale-up factor of fixed signal point actual size, this scale-up factor is used to realize the unit conversion of camera measurement overall process;

Step 4: carry out the sampling analysis process repeatedly of the moving displacement of observation monument, and the movement locus of record mark point, draw corresponding displacement-time curve simultaneously.

2. the method for the moving displacement measurement of one camera multi-measuring point according to claim 1 is characterized in that: described sampling analysis process repeatedly is to realize by the while circulation that a continuous sampling is analyzed; Each cyclic process comprises: at first, utilize Vision Acquisition software to read the instant photo of a fixed signal, will notice in the measuring process guaranteeing that the border of fixed signal can not surpass the field range of camera in the process of moving together along with testee from camera; Then, " Locate Edges " order that utilizes LabVIEW software to provide is carried out marginal analysis and location to the instant photo that comprises the border, and obtains the centre of form coordinate of fixed signal; At last,, be presented on the computer screen in real time, and input system is carried out the data deposit the real time position of this centre of form coordinate as testee.

3. the method for the moving displacement measurement of one camera multi-measuring point according to claim 2 is characterized in that: described while circulation is to stop control knob by the outside to finish sampling analysis.

4. the method for the moving displacement measurement of one camera multi-measuring point according to claim 1, it is characterized in that: described definite shape comprises circle, triangle, quadrilateral or pentagon.

5. the method for the moving displacement measurement of one camera multi-measuring point according to claim 1, it is characterized in that: described high speed camera is by 1394 data connecting lines and sampling analysis system communication.

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