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First, the steps of the technical design of the engineering control network
1.According to the purpose, requirements and control scope of the control network, the graphics and reference datum (starting data) of the control network are determined after planning on the map and field survey.
2.According to the conditions of the measuring instrument, the observation method and the prior accuracy of the observation value are formulated.
3.According to the manpower and material resources required for observation, the budget controls the cost of network construction.
4.According to the prior accuracy of the control network graphics and observations, the accuracy of the control network results is estimated, and the layout scheme is improved.
5.According to the need, the optimal design of the control network is carried out.
2. Optimal design of measurement and control network
1. Measurement and control network quality criteria
Accuracy criterion: includes indicators such as total accuracy, point accuracy, relative point accuracy, and accuracy of unknown functions.
Reliability criterion: The ability to find (or detect) gross errors in observations (called internal reliability) and the ability to resist the influence of gross errors in observations on the adjustment results (called external reliability).
The higher the accuracy requirements, the more expensive the instruments and equipment used, and the higher the network construction cost. The higher the reliability requirements, the more observations and the higher the network construction cost.
Sensitivity criterion: For the deformation monitoring network, it is defined as the lower bound value of the deformation displacement vector that can be found by statistical testing of the adjustment results of periodic observations under a given level of significance and test power.
2. Classification of optimal design of measurement and control network
Zero-order design: It is a datum design, which is the selection and determination of the coordinate system and datum under the condition that the network shape and observation accuracy are constant.
First-order design: For graphic design, the position of the dot is adjusted under the condition of observation accuracy and coordinate vector cofactor matrix.
Second-order design: The design for the observation accuracy is to change the observation accuracy under the condition that the cofactor matrix of the network and coordinate vector is constant.
Third-order design: Improvements to existing networks.
3. Optimal design method of control network
Analytic method: The analytic method is usually solved under constraints, the extreme value or directly through matrix operation.
Simulation method: The simulation method is to quickly calculate the accuracy, reliability and other indicators of the control network through the computer, and compare with the design value, and the measurement engineer modifies the layout plan according to professional knowledge and experience until an optimized and feasible plan is obtained.
The optimal design of control network has been continuously developed in both theoretical research and practical application. The optimal design of the control network can be divided into two types: analytical method and simulation method, which are based on the accuracy, reliability, cost and sensitivity of the control network.
The analytical method and the simulation method have their own advantages and disadvantages, and in general, the results of the analytical method are optimal, but they are not necessarily feasible. The results of the simulation method are not necessarily optimal, but they are feasible. Since the simulation method can be carried out in the form of human-computer interaction using a general adjustment program, it is more adaptable and easier to generalize.