CN102944205B - Static calibration method of continuous linear measurement system - Google Patents

Abstract

The invention proposes a static correction method for a continuous line shape measurement system. In this method, a static calibration bridge is placed on the measured road section, and the bridge height is measured by a length measurement tool; the continuous linear measurement system is used to detect the road section containing the calibration bridge, and the linear curve containing the calibration bridge is obtained through linear calculation. Calibrate the calculated bridge height of the bridge, compare the calculated bridge height with the actual measured bridge height, and obtain the vertical axis coordinate correction coefficient, and use this coefficient to correct the overall measurement linear curve, thereby improving the linear measurement accuracy. The invention is suitable for continuous alignment detection of various roads, bridges and tunnels in the field of road traffic.

Description

A Static Calibration Method for Continuous Lineshape Measurement System

technical field

The invention relates to a correction method for a structural alignment detection system of various roads, bridges and tunnels in the field of road traffic.

Background technique

Deformation monitoring of highway subgrade, bridges and tunnels is crucial to ensure the structural safety of traffic engineering. Soft soil subgrades in highways are prone to deformation problems such as settlement and errors. Ordinary detection methods cannot meet the high-precision long-distance lead measurement. The bridge structure will deform under the action of external force, and various diseases such as cracks, prestress loss, etc. will eventually lead to changes in the alignment of the bridge, and the alignment displacement is the most important and intuitive reference index for judging the safety of the bridge. During the long-term operation and use of the tunnel, the most concerned safety issue is to prevent the tunnel from collapsing. Timely and fast grasp of the direction of the tunnel and the circumferential deformation of the area with poor surrounding rock conditions is an important task to ensure the safety of the tunnel operation.

The accuracy requirements for deformation monitoring in the field of road traffic must meet the corresponding national evaluation standards. For example, in the current common cable-stayed bridges, if the main spans are respectively steel box frame stiffened girders, prestressed concrete girders and steel truss stiffened girders, the maximum allowable mid-span deflection is 1/400, 1/500 and 1/ 800. If the span is 500m, the maximum allowable mid-span deflection of the above-mentioned bridges is 1.25m, 1m and 0.625m respectively. However, the annual observation data shows that the mid-span deflection of large bridges with a downward deflection tendency is only 2-3 mm per year, and the mid-span deflection of small and medium-sized bridges is even only 1-2 mm. Accordingly, the accuracy of the linear measurement system is required to be on the order of millimeters.

Conventional methods for alignment detection of roads, bridges and tunnels mainly use optical instruments to measure through the establishment of a level control network, and long-term monitoring mainly uses new test methods such as connected pipe test systems, laser measurement systems, photoelectric image measurement systems, and GPS methods.

The establishment of the leveling control network is complex, time-consuming and greatly affected by the environment. The connecting pipe test system obtains the deflection value of each measuring point by measuring the liquid level pressure difference between each measuring point and the reference point. Not only does it need to pre-lay water pipes, but it also has disadvantages such as slow response time and high construction and maintenance costs during use. The laser measurement system and the photoelectric image measurement system mainly capture the position change of the light spot or imaging through the optical system to obtain the relative position change of the light source. Both of these two measurement systems must install fixed equipment on the bridge as a reference point. When the equipment is moved, the initial measurement reference state cannot be obtained, which cannot meet the long-term measurement requirements, and different climatic conditions have an impact on the measurement.

GPS technology receives the carrier phase difference data of navigation satellites to measure the three-dimensional coordinates of the site in real time, which is a new type of real-time measurement technology. GPS is less affected by the outside atmosphere, can monitor in storms, and can realize automatic monitoring of three-dimensional coordinates. However, this technology has the disadvantages of poor vertical elevation accuracy, unable to achieve millimeter accuracy, and high cost, which prevents it from being applied on a large scale. In addition, when performing multi-point precise measurement, it requires a long static test time for each point, and the test is slow.

In addition to their different application limitations, the above technologies also have the problem of discontinuous line shape due to fitting the deflection line shape of the detection object through a small number of measuring points.

The angular velocity sensor can be used for continuous angle measurement, and the continuous linear coordinate data can be obtained by converting the continuous angular velocity value, which effectively overcomes the defects of the above technologies. The method has the advantages of rapidity, convenience, simple operation, good continuity, and high real-time performance. It can conduct regular or non-regular rapid detection of the alignment of various road surfaces and tunnels without hindering traffic.

At present, the angular velocity sensor generally adopts a fiber optic gyroscope with high precision. The fiber optic gyroscope has the advantages of high reliability, long life, fast startup, light weight, small size and high precision, and is widely used in the fields of inertial navigation and engineering measurement. The basic parameters of the fiber optic gyroscope determine its stability and accuracy. These basic parameters include zero bias, zero bias stability, random walk coefficient, scale factor, scale factor nonlinearity, asymmetry and repeatability. However, due to factors such as the stability of the components of the fiber optic gyroscope and the drift of the light source, errors inevitably occur in the output of the fiber optic gyroscope. The output error of fiber optic gyroscope includes zero bias correlation error and scale factor error. Zero bias (repeatability) random drift, environmental sensitivity drift and output quantization noise cause zero bias error, asymmetry of scale factor, nonlinear repeatability and temperature sensitivity, etc. affect the accuracy of scale factor. Gyro error will increase with time drift and temperature changes.

In the process of bridge alignment measurement, the fiber optic gyroscope is pulled by the carrier to advance on the bridge deck and the road surface. The increment of the linear curve coordinates is obtained through the integral operation of the angular velocity and the odometer signal, and the coordinates of all measurement sampling points relative to the starting point are obtained by further integration. Due to the inherent error formation mechanism of integral calculation, the error of coordinate calculation value will increase with the increase of measurement time. Therefore, when this continuous measurement technique is used for measurement, the error tends to gradually diverge and expand as the measurement progresses. Therefore, it is necessary to use a calibration method to calibrate the measurement data to reduce the systematic error in the linear measurement process.

Existing patents (application numbers: CN201010574097.9 and CN200910073154.2) propose an attitude calculation and filtering method combined with GPS data for the fiber optic gyro system itself. The above two patents only propose a basis for the fiber optic gyro strapdown inertial navigation system The algorithm for real-time correction of GPS data does not involve the timely correction of trajectory measurement errors.

In the existing patent (application number: CN201210116750.6), a method of measuring the line shape and rigidity curve of the bridge using a fiber optic gyro line shape measurement system was proposed, and a variety of methods to reduce the error were mentioned, but this patent only used data analysis. Analysis achieves the purpose of reducing errors, and there is no external calibration and correction method.

Contents of the invention

The invention relates to a method for correcting continuous line shape measurement based on an angular velocity sensor. The continuous linear measurement system includes a distance sensor and an angular velocity measurement unit, and its calculation principle is as follows:

${\mathrm{<span\; class="notranslate">\; x</span>}}_{\mathrm{<span\; class="notranslate">\; m</span>}}<span\; class="notranslate">\; =</span>\underset{\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{\mathrm{<span\; class="notranslate">\; m</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}\mathrm{<span\; class="notranslate">\; L</span>}<span\; class="notranslate">\; \&Center\; Dot;</span>\mathrm{<span\; class="notranslate">\; cos</span>}<span\; class="notranslate">\; (</span>\underset{\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{\mathrm{<span\; class="notranslate">\; no</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}{\mathrm{<span\; class="notranslate">\; \&omega;</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; \&Center\; Dot;</span>{\mathrm{<span\; class="notranslate">\; t</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>$

${\mathrm{<span\; class="notranslate">\; Y</span>}}_{\mathrm{<span\; class="notranslate">\; m</span>}}<span\; class="notranslate">\; =</span>\underset{\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{\mathrm{<span\; class="notranslate">\; m</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}\mathrm{<span\; class="notranslate">\; L</span>}<span\; class="notranslate">\; \&Center\; Dot;</span>\mathrm{<span\; class="notranslate">\; sin</span>}<span\; class="notranslate">\; (</span>\underset{\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{\mathrm{<span\; class="notranslate">\; no</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}{\mathrm{<span\; class="notranslate">\; \&omega;</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; \&Center\; Dot;</span>{\mathrm{<span\; class="notranslate">\; t</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; )</span>$

In the formula, X _m and Y _m are the abscissa and ordinate respectively, L is the distance between two sampling points, and ω _i is the instantaneous angular velocity measured by the angular velocity measuring unit. t _i is the time interval between two sampling points. Since the calculation of this linear coordinate is based on a double integral operation, any errors in the intermediate data will be added to the final result. It can be seen from the formula that there may be errors in the distance sensor, angular velocity sensor and time measurement values. Therefore, it is necessary to take an effective method to calibrate the calculation results of the linear curve.

The present invention proposes a static correction method for a continuous line shape measurement system, and the technical solution of the present invention is:

Place a static calibration bridge on the measured road section, and use the length measurement tool to measure the bridge height. The continuous linear measurement system is used to detect the road section containing the calibration bridge, and the linear curve containing the calibration bridge is obtained through linear calculation. The calculated bridge height of the calibration bridge can be obtained from the linear curve, and the calculated bridge height is compared with the actual measured bridge height to obtain the correction coefficient of the vertical axis coordinates, which is used to correct the overall measurement linear curve.

Specific method steps:

1), using a continuous linear measurement system to measure the linear shape of the measured road section;

2) Place the static calibration bridge on the road section to be tested, and measure the actual bridge height;

3) Carry out linear measurement on the measured road section containing the calibration bridge, obtain the linear curve containing the calibration bridge through linear calculation, and obtain the calculated bridge height of the calibration bridge from the linear curve;

4) Comparing the calculated bridge height obtained by using the linear data with the measured bridge height, using the measured bridge height to correct the measured bridge height, and then correcting the linear data of all measured road sections.

In the static correction method of the present invention, the calibration bridge is placed at any position of the measured road section.

In the static correction method of the present invention, the measured accuracy of the bridge height of the calibration bridge is 0.01 mm.

Description of drawings

Fig. 1 is the flow chart of the static correction method of the continuous line shape measuring system of the present invention;

Figure 2 is a schematic diagram of measuring the static calibration bridge height;

Fig. 3 is the linear schematic diagram of the measured road section of the bridge without static calibration of the present invention;

Fig. 4 is the linear schematic diagram of the measured road section that has static calibration bridge 1 of the present invention;

Among the figure: 1 is the static calibration bridge, 2 is the line shape of the measured road section without the static calibration bridge, and 3 is the line shape of the measured road section with the static calibration bridge 1.

detailed description

The static correction method flow chart of a kind of continuous line shape measurement system of the present invention is shown in Figure 1, and its typical process is:

1. Measure and calibrate the bridge height h _m , the actual measurement accuracy is 0.01 mm, as shown in Figure 2;

2. Measure the alignment of the measured road section without the calibration bridge, as shown in Figure 3;

3. Measure the alignment of the measured road section where the calibration bridge is placed, as shown in Figure 4;

4. Analyze and compare the two measurement results. Calculate the bridge height h _c by calculating the linear curve, calculate the ratio of h _m and h _c to obtain the correction coefficient λ of the vertical axis coordinate, and use this coefficient to correct the vertical coordinate of the overall linear curve.

For the calculation method of the linear curve, refer to formula (1) in the manual.

It can be foreseen that those skilled in the art can develop various application examples based on the spirit of the present invention, and any modifications that do not depart from the spirit or scope of the present invention shall fall within the protection scope of the present invention.

Claims (4)

1. A static correction method for a continuous line shape measurement system, characterized in that the method is: Place a static calibration bridge on the measured road section, use the length measurement tool to measure the bridge height; use the continuous linear measurement system to detect the road section containing the calibration bridge, and obtain the linear curve containing the calibration bridge through linear calculation; get the calibration bridge from the linear curve Comparing the calculated bridge height with the actual measured bridge height, the vertical axis coordinate correction coefficient is obtained, which is used to correct the overall measurement linear curve. 2. the static correction method of a kind of continuous line shape measuring system according to claim 1, is characterized in that, method step is: 1) Using a continuous linear measurement system to measure the linearity of the measured road section; 2) Place the static calibration bridge on the road section to be tested, and measure the actual bridge height; 3) Measure the alignment of the measured road section containing the calibration bridge, obtain the alignment curve containing the alignment bridge through alignment calculation, and obtain the calculated bridge height of the alignment bridge from the alignment curve; 4) Comparing the calculated bridge height obtained by using the linear data with the measured bridge height, using the measured bridge height to correct the calculated bridge height, and then correcting the linear data of all measured road sections. 3. The static correction method of a continuous linear measurement system according to claim 1 or 2, characterized in that the calibration bridge is placed at any position of the measured road section. 4. A static correction method for a continuous linear shape measurement system according to claim 1 or 2, characterized in that the measured accuracy of the bridge height of the calibration bridge is 0.01 mm.