Key words: engineering survey, industrial survey, precision engineering survey, optimal design of engineering survey robot network I. Current situation of disciplines and research and application fields.
Discipline definition
Engineering surveying is an applied discipline that studies the theoretical methods and techniques of measuring and describing specific geometric entities and realizing the layout of abstract geometric entities in the earth space. Mainly in construction engineering, machinery and equipment.
Theme state
Surveying and mapping science and technology is a first-class discipline with a long history and modern development. No matter how the discipline develops, how the service field is broadened, how the intersection with other disciplines is increased or strengthened, how the discipline is integrated and subdivided, and how the name of the discipline is changed, the nature and characteristics of the discipline will not change. Generally speaking, the two disciplines of the whole discipline should still be divided into the following:
-Geodesy;
-Engineering survey;
-Aerial photogrammetry and remote sensing;
Cartography;
Real estate cadastre and land consolidation.
Research and application fields
At present, engineering investigation related to engineering construction in China is divided into three stages: survey and design, construction and operation management. It is also divided into: line engineering survey, water conservancy engineering survey, bridge and tunnel engineering survey, construction engineering survey, mine survey, marine engineering survey, military engineering survey, three-dimensional industrial survey and so on. Almost every industry and engineering survey has corresponding books or teaching materials.
Engineering Surveying compiled by Germans Hennecke, Mill and Werner is mainly divided and compiled according to the following contents: ① measuring instruments and methods; (2) Line, railway and highway construction survey; ③ High-rise building survey; ④ Underground building survey; ⑤ Safety monitoring; ⑥ Measurement of machinery and equipment.
The research and application fields of engineering survey are very extensive and developing very rapidly, so it is very difficult to write a book. At present, there is no modern monograph or teaching material at home and abroad that comprehensively involves the theory, technology, method and practical application of engineering survey.
The Sixth Committee of the International Federation of Surveyors is called the Engineering Survey Committee. In the past, it had four working groups: investigation methods and tolerance; Earthwork calculation; Deformation measurement; Underground engineering survey. In addition, a special group was set up: deformation analysis and interpretation. At present, there are six working groups and two thematic groups. The six working groups are: high-precision measurement technology and method of large-scale scientific equipment; Line engineering survey and optimization; Deformation measurement; Engineering survey information system; Application of laser technology in engineering survey: electronic science and technology literature and network. These two thematic groups are: special measuring instruments in engineering and industry; Engineering survey standard.
Since 1950s, Germany, Switzerland and Austria, three German-speaking countries, have initiated and organized the "International Symposium on Engineering Survey" held every 3-4 years. In the past, engineering survey was divided into the following topics: measuring instruments and data acquisition; Data interpretation, processing and application; High-rise buildings and equipment installation survey; Underground and deep building survey; Deformation monitoring of environment and engineering buildings.
The topic of 1 1 seminar 1992 is: measurement theory and measurement scheme; Measurement technology and measurement system; Information system and CAD；; Applications in building engineering and industry.
1996 12 the theme of the seminar is: measurement and data processing system; Monitoring and control; Quality problems in industrial and architectural engineering; Data model and information system; Cross-disciplinary large-scale engineering projects.
As can be seen from the above, the research field of engineering survey is relatively fixed and constantly developing and changing. The author thinks that engineering survey mainly includes two parts: engineering survey of engineering buildings and industrial survey of equipment and machinery installation. It can be divided into general engineering survey and precision engineering survey. The main task of engineering survey is to provide surveying and mapping support for all kinds of engineering construction and meet the requirements of engineering. Precision engineering survey represents the development direction of engineering survey, and the construction of large-scale special precision engineering is the driving force to promote the development of engineering survey. Second, the development of engineering measuring instruments Engineering measuring instruments can be divided into general instruments and special instruments. Conventional optical theodolite, optical level and electromagnetic wave range finder in general instruments will be gradually replaced by electronic total station and electronic level. With the enrichment of software, computer total station is developing towards omnipotence and intelligence. The total station driven by motor and controlled by program, combined with laser, communication and CCD technology, can realize full automation of measurement, and is called measuring robot. The measuring robot can automatically find and accurately aim at the target, complete the observation of a target point within 1s, and can continuously and repeatedly observe hundreds of targets like a robot, which can be widely used in deformation monitoring and construction survey. GPS receiver has gradually become a universal positioning instrument and is widely used in engineering survey. Connecting a GPS receiver with an electronic total station or a measuring robot is called a super total station or a super measuring robot. It perfectly combines the real-time dynamic positioning technology of GPS with the flexible three-dimensional polar coordinate measurement technology of total station, and can realize various engineering surveys without control network.
Special instrument is the most active instrument in engineering survey, which is mainly used in the field of precision engineering survey. These include mechanical, photoelectric and photoelectric instruments or measuring systems. Its main features are high precision, automation, telemetry and continuous observation.
Used to establish a horizontal or vertical datum line or datum plane and measure the target point relative to the datum plane.
The deviation of the line is called baseline measurement or collimation measurement. Instruments in this field include front and rear hammers and vertical observation instruments, line stretching lines, various laser collimators, vertical collimators, autocollimators and nylon wire or line collimation measurement systems.
In the aspect of distance measurement, it includes accurate measurement of medium and long distance, short distance, micro distance and their changes. The precision laser rangefinder, represented by ME5000 and TERRAMETERLDM2 dual-frequency laser rangefinder, can achieve sub-millimeter measurement accuracy in the middle and long distance; Fortunately, many short-distance and micro-distance measurements have realized the automation of measurement data collection, among which DISTINVAR, Distermeterism, timely strain gauges, various optical strain gauges, laser displacement and vibration rapid telemeters are the most typical ones. The dual-frequency laser interferometer with Doppler effect can reach the measurement accuracy of 0.065438 0 μ m in the range of tens of meters, and has become an important length calibration and precision measurement equipment. Using CCD linear array sensor to measure the macro range can reach the accuracy of several microns, which makes the ranging accuracy enter the nano-scale world from millimeter and micron level.
In the aspect of elevation measurement, the most remarkable development is the static leveling system. This system measures the liquid level of the container through various sensors, and can obtain the heights of dozens or even hundreds of monitoring points at the same time. It has the characteristics of high precision, telemetry, automation, mobility and continuous measurement. The distance between the two containers can reach tens of kilometers, for example, for leveling across rivers and straits; Through the pressure sensor, the height difference between the two containers can reach several meters from the past few centimeters.
Related to elevation measurement is inclination measurement, that is, to determine the deflection curve of the measured object relative to the horizontal or vertical datum line in the vertical plane. Various mechanical inclinometers and electronic inclinometers are developing in the direction of digital display, automatic recording and flexible movement, and their accuracy reaches micron level.
Multifunctional hybrid measurement system is a remarkable feature of the development of special instruments for engineering measurement. The multi-sensor high-speed railway track measurement system is adopted, and the measuring robot is used to automatically track the measuring vehicle moving along the railway track. The measuring vehicle is equipped with prism, inclination sensor, length sensor and microcomputer, which can be used to measure the three-dimensional coordinates of the track, the width and inclination of the track. The hybrid measuring system, which integrates static leveling and traverse alignment, can accurately measure the elevation and offset of the measuring point on a reference line hundreds of meters long.
To sum up, the special instrument for engineering survey has the characteristics of high precision, rapidity, telemetry, non-contact, mobility, continuity, automatic recording and microcomputer control. It can be used for precise positioning and collimation measurement, and can measure inclination, thickness, surface roughness and straightness, as well as vibration frequency and dynamic behavior of objects. Third, the development of engineering survey theory and method, survey adjustment theory
Least square method is widely used in survey adjustment. Least square configuration includes adjustment, filtering and estimation. Conditional adjustment model with constraints is called generalized adjustment model, which is a unified model of various classical and modern adjustment models. The theory of measurement error is mainly manifested in the study of model error, which mainly includes: identification or diagnosis of functional model error and random model error in adjustment; The influence of model error on parameter estimation and the statistical properties of parameters and residuals; Relationship between ill-conditioned equation and control network design and its observation scheme. Because of the need to check the stability of datum points of deformation monitoring network, free network adjustment and quasi-stable adjustment have appeared and developed. The study of gross error of observation value promotes the research and development of reliability theory of control network and the theory of distinguishing gross error between deformation and observation value of deformation monitoring network. In view of the objective fact that there are gross errors in the observed values, robust estimation appears; Aiming at the possibility of ill-conditioned coefficient matrix of normal equation, a biased estimation is proposed. Unlike least squares estimation, robust estimation and biased estimation are called non-least squares estimation.
Balda's data detection method is effective when there is only one gross error in the observed value, and the robust estimation method has the advantage of resisting the influence of multiple gross errors. By establishing the functional relationship between the correction vector of the observed value and the true error vector, multiple gross errors can be located and repaired at the same time. This method has been implemented and applied in the general adjustment software package.
The estimation of variance and covariance components is essentially a stochastic model of refined adjustment, which used to stay in theoretical research. In practice, it is necessary to comprehensively process a variety of observations, so variance component estimation becomes a necessary content of survey adjustment. At present, this function has been added to the general adjustment software package, but it needs to be clearly put forward in the survey specification.
It should be pointed out that many measuring units like to use attached wires for step-by-step encryption, mainly according to the current specifications for primary, secondary and tertiary wires and root wires. There is no doubt that the attached traverse has many advantages, but due to the few redundant observations, the ability to find and resist gross errors is weak and it is not suitable for abuse. Establish the control of an area, the first-level network points are measured by GPS, and it is best to use the first-level traverse network for comprehensive encryption below. From the point of view of survey adjustment theory, the comprehensive layout of traverse network has better graphic strength, more uniform accuracy and higher reliability.
Theory and method of optimal design of engineering control network
There are two methods for network optimization design: analytical method and simulation method. Analytical method is based on optimal design theory to construct objective function and constraint conditions, and to solve the maximum or minimum value of objective function. Generally, the quality index of the network is regarded as the objective function or constraint condition. The quality index of the network mainly includes accuracy, reliability and network construction cost, and also includes the sensitivity or resolution of the deformation monitoring network. For the adjustment model of network, according to the difference between fixed parameters and undetermined parameters, the optimal design of network can be divided into zero, one, two and three types, which involve the benchmark design, network shape, observation accuracy and observation scheme design of network. In engineering survey, the construction control network, installation control network and deformation monitoring network need to be optimized. Because of GPS positioning technology and electromagnetic wave ranging, the concept of network geometry is very different from the traditional angle measuring network. In addition to the very precise control network, we can consider using a specially written analytical optimization design program to optimize the design of the network, and other networks can be designed by simulation. The software function of simulation optimization design and the steps of optimization design mainly include: according to the design data and map data, select points on the map and lay out the network to get the approximate coordinates of nodes. The simulation observation scheme can further simulate the observation value by determining the accuracy of the observation value according to the instrument. Calculate various quality indexes of the network, such as accuracy, reliability and sensitivity. Accuracy should include point accuracy, adjacent point accuracy, relative accuracy between any two points, weakest point and weakest edge accuracy, side length and azimuth accuracy. Furthermore, the covariance matrix of unknown coordinates or partial point coordinates, the principal component calculation of covariance matrix, eigenvalue calculation, point error ellipse and confidence ellipse can be calculated. Reliability includes the influence of redundant observation components of each observation and gross error limit of an observation on adjustment coordinates. Sensitivity includes sensitivity ellipse, sensitivity index under given deformation vector and sensitivity influence coefficient of observed value. Compare the calculated quality index with the index required by the design, so that it can meet the design requirements without too much surplus. By changing the accuracy of observation values, changing the observation scheme or partially changing the network shape, the above design and calculation are carried out again until better results are obtained.
In practice, the following optimization design strategies are summarized: First, the accuracy of observation values is fixed, all possible edges and directions are observed for the selected nodes, and the network quality index is calculated. If the quality is low, the accuracy of the observation value must be improved. Under a certain set of prior precision, if the quality index of the network is high, then the observation value can be deleted according to the internal reliability index ri of the observation value. Ri is too large, indicating that the observed value is redundant and should be deleted; If ri is very small, the accuracy of the observed value should not be increased. This method of deleting observations according to the size of ri is called the optimization strategy from "dense" to "sparse" and from "fat" to "thin".
From the whole process of simulation optimization design, it is a trial algorithm and needs a good software. The software not only has the function of general adjustment software, but also has higher requirements in the diversity and intuition of output results, visualization and human-computer interaction interface design. At the same time, designers are required to have solid professional knowledge and rich experience.
Through the simulation method, a relatively optimal and feasible scheme can be obtained, which can be further used to calculate the adjustment of the network. At the same time, the gross error of observation can be simulated and the influence on the results can be calculated. This method is called mathematical distortion method or Monte Carlo method. For the monitoring network or precision control network which requires high accuracy, reliability and sensitivity, the above-mentioned optimization design and fine calculation are needed. Domestic application in this field
There are fewer roads. Most of them are for safety reasons, with large quality surplus and high network construction cost. The cost of network optimization design is very small, which brings great benefits. All the more important engineering control networks should be optimized.
Deformation observation data processing
Monitoring, analysis and prediction of engineering buildings and engineering deformation are important research contents of engineering survey. Deformation analysis and pretreatment include deformation observation data processing. However, the scope of deformation analysis and prediction is wider and belongs to the intersection of many disciplines.
Several typical methods of deformation observation data processing