引言 I. Introduction
在实际测量工作中，大型油罐、烟囱等罐状体由于受到外界作用力的影响，在使用一定时间后需要对其形状、容积等重新进行测量以判断是否发生变化，因此罐体检测成为必不可少的工作。 In actual measurement work, tanks such as large oil tanks and chimneys are affected by external forces. After a certain period of use, the shape and volume of the tanks need to be re-measured to determine whether changes have occurred. Therefore, the tank detection becomes Essential work. The inspection scan needs to scan the entire tank at a certain height, and requires high measurement accuracy and the amount of deformation of the entire tank. Manual labor is labor-intensive and inefficient, and because the tank is not easy to place reflective prisms, it is considered A non-prism measuring robot is used to complete the scanning and inspection tasks of the tank.
The measuring robot is a kind of intelligent electronic total station which can replace the manual search, tracking, recognition and precise aiming of the target and obtain the angle, distance, three-dimensional coordinates and image. CCD影像传感器构成的视频成像系统，并配置智能化的控制及应用软件发展而成。 It is a video imaging system that integrates a stepping motor and a CCD image sensor based on the total station, and is equipped with intelligent control and application software. Its target automatic search, recognition and accurate sighting function can continuously and repeatedly observe multiple target points in a short time. At present, some measuring robots do not need to cooperate with targets, and can according to the object's feature points, contour lines and textures. The image processing method is used to automatically identify, match and aim the target, and obtain the three-dimensional coordinates and shape of the target, which has become the first choice for tank scanning detection.
TM30 is a prism-free measuring robot launched by Leica Geosystems in 2009. The instrument has high measurement accuracy, high speed, and is fully automated. It can ensure uninterrupted work around the clock. Leica TM30 is equipped with accurate automatic sighting, fast and reliable intelligent automatic identification system, automatic target recognition measuring range up to 3000m and accuracy of millimeter level, this technology can greatly increase the monitoring radius, reduce equipment and capital investment. The digital image acquisition function of TM30 can capture the image information of the monitoring point at the time of measuring point, save and transmit, and understand the visibility and potential risks of the monitoring area in real time while remotely controlling. The new generation of PinPoint EDM ranging technology used by this instrument can achieve higher ranging accuracy. The ranging accuracy with prism is ± (0.6mm + 1 × 10-6D), and the non-prism ranging accuracy is ± (2mm ＋ 2 × 10-6D) ), The measurement range without prism is more than 1000m. There are two choices of angle measurement accuracy: ± 0.5 "and ± 0.1", which can ensure the high reliability of each measurement, and can be used in the most severe working environment. TM30 also provides on-board programs, and special programs can be written on the GeoC ++ platform to meet the actual needs of users. It has great advantages and application prospects in the scanning and detection of tanks.
Software and programming framework
2.1 Features and advantages of GeoC ++ development
TM30测量机器人提供了GeoC++的软件开发平台，该开发工具采用面向对象的方法，具有丰富的应用函数，功能强大。 The Leica measurement system provides a GeoC ++ software development platform for the TM30 measurement robot. The development tool adopts an object-oriented method, has rich application functions, and is powerful. The development system also provides an instrument simulator, which can simulate the instrument environment debugging program by software method.
The GeoC ++ programming framework is shown in Figure 1. It includes two measurement modes, GPS and TPS, and each has its own hardware and applications. It also contains general hardware and applications. The hardware libraries are: GPS hardware, TPS hardware, general hardware, database, coordinate transformation, geometry, and data obtained from sensors.
2所示，一般的，每一个机载应用程序都包括以下四个类： The software library is shown in Figure 2. In general, each on-board application includes the following four categories:
An application class (Application class), which is inherited from GUI :: ApplicationC;
One or more coroller classes. The controller class belongs to the application class. This class is inherited from GUI :: ControllerC. The controller class is used to generate and maintain the dialog class, such as opening and closing dialog boxes or clicking a function. key;
One or more model classes. The model class belongs to the application class or the controller class. The model class is derived from GUI :: ModelC. Generally, the model class contains the data required by the application;
One or more dialog classes. The dialog class belongs to the controller class, and each controller class contains at least one dialog class. In order to make it easier to obtain application data in the dialog class, you need to inherit the GUI :: ModelHandlerC base class.
2.2 Main function modules of tank scanning monitoring
3所示。 Tank scanning is the scanning measurement of tank deformation. Its main functional modules include: scan settings, base circle scanning and tank scanning. The scanning interface is shown in Figure 3.
3 罐体扫描选择界面 Figure 3 Tank scanning selection interface
2.2.1 Scan settings
4所示。 Scan settings include: base circle scan setting (automatic or manual), base circle scan mode (partial or full scan), scan height interval setting, scan step (distance, angle, equal division), step input, etc .; scan settings The interface is shown in Figure 4. The basic circle scanning settings are divided into automatic scanning and manual scanning. The user can choose according to actual needs. If automatic scanning is selected, the scanning method needs to be set-partial scanning or full scanning, and partial scanning is based on the set starting point and Finish the scan at the coordinates of the end point. After setting the base circle scan information, you need to set the entire tank scanning height interval and scanning step. The height interval is to scan the tank horizontally according to the set height. Scan by distance, angle, or division, and set the step length input for each step mode, and the scan setting is completed.
4 扫描设置界面 Figure 4 Scan settings interface
2.2.2 Basic circle scan
Base circle scanning includes: base circle determination and base circle scanning. 5所示。 The determination of the base circle is to manually scan the three control points, initially determine the center and radius of the tank body, and then automatically or manually scan the base circle according to the base circle scan settings, and perform data fit analysis on the scan results. Figure 5 shows.
5 基圆扫描界面 Figure 5 Basic circle scanning interface
2.2.3 Tank scanning
6所示。 The tank scanning is to automatically scan the cross-sections of tanks at different heights to complete the entire tank scanning according to the scanning height interval setting result. The tank scanning interface is shown in FIG. 6.
6 罐体扫描开始界面 Figure 6 Tank scanning start interface
Algorithm introduction and example analysis
3.1 Adjustment Principle
The data processing uses a direct least squares circle fitting algorithm based on robust estimation. Since the cross section of the tank is generally a standard circular surface, the circular equation can be expressed as:
1 ） ( 1 )
Where R 为圆的半径。 Is the center coordinate; R is the radius of the circle.
For measuring points , Whose error equation is:
2 ） ( 2 )
2 ）式进行线性化后，并令 After linearizing ( 2 ), let
, The equation is:
3 ） ( 3 )
The iterative initial value of the circle center coordinate and radius during the solution process can be taken as the circle center coordinate and radius determined at three points. However, in the actual measurement process, due to the existence of gross errors, the fitting accuracy is reduced, and even the fitting results are deviated. Therefore, a weight function is required to eliminate the gross errors. The weight function is calculated as follows:
4 ） ( 4 )
Where n 为观测个数， t 为必要观测数。 , N is the number of observations, and t is the number of necessary observations. P 取为单位阵，第 2 、 3 、 4 次迭代取 The above solution needs to be completed iteratively, where P is taken as the unit matrix in the first iteration, and taken in the 2nd , 3rd and 4th iterations. Fetch later Iteration ends when the weights remain essentially unchanged.
3.2 Data analysis
TM30 的 GeoC++ 平台开发的罐体扫描检测程序对某油罐进行扫描，该油罐高度为 8m ，半径为 6m ，由 8 段组成，每一段的高度为 1.5m ，分别在每段的 1/4 、 3/4 高度处扫描横截面，基圆采集数据如表 1 所示。 A tank scan program developed based on the TM30 GeoC ++ platform was used to scan an oil tank. The height of the tank is 8m and the radius is 6m . The tank is composed of 8 segments, and the height of each segment is 1.5m . Scan the cross section at the heights of / 4 and 3/4 . The collected data of the base circle is shown in Table 1 .
1 基圆采集数据 Table 1 Base circle collection data
12.8775,1.8391 ），半径为 5.9717m 。 According to the data collected from the base circle, the center coordinates of the tank are: ( 12.8775 , 1.8391 ), and the radius is 5.9717m . 0.00279m ，拟合偏差结果如示。 The least square circle fitting algorithm based on robust estimation was used to analyze the collected data of a certain tank body, and the fitting accuracy was 0.00279m . The results of the fitting deviation are shown as follows .
2 罐体采集数据分析 Table 2 Tank collection data analysis
The least square circle fitting algorithm based on robust estimation can reduce the influence of the gross error on the fitting result and ensure the accuracy of the fitting. Therefore, it is accurate and reliable to use this algorithm in the tank scanning detection software.
Fourth, concluding remarks
This paper introduces the development platform GeoC ++ of the Leica TM30 measuring robot and the development of a tank scanning detection application on this platform. At the same time, it introduces the algorithm used in the development, the least square algorithm based on robust estimation, and will be applied to actual The calculation accuracy of the project is explained. The instrument and method used in this article have the following advantages: The Leica TM30 measuring robot has high measurement accuracy, and the prism-free technology greatly saves manpower and material resources, improves work efficiency and reduces costs; GeoC ++ airborne software does not need to be connected to the machine, and is easy to use. There are certain advantages in practical engineering applications; the least squares algorithm based on robust estimation can eliminate gross errors, improve the fitting accuracy, and the fitting results are consistent with the actual situation.