Research On Key Technology For Measuring Shield Machine's Position And Orientation

Shield machine, which is closely related with subjects of mechanical engineering, electrical engineering, hydraulic, measurement, control and material etc, is a type of large-scale full-face excavation equipment used for tunnel construction. Shield tunneling method, which has the advantage of high efficiency of construction, high degree of automation, savings in manpower, and having no interference from ground, will be used in subway construction project in china increasingly. The measurement and guidance system, serving as the "eyes" of shield machine, now plays a vital role in shield tunnel construction.At present, shield machines manufactured in China need to be equipped with foreign measurement and guidance system to achieve automatic guidance during the tunneling process. The related equipment of foreign system is expensive to purchase or hire, so it is of great significance to develop measurement and guidance system of shield machine with independent intellectual property rights in China. Supported by national 973 project, the key research work of this dissertation is carried out as follows: Firstly, mathematical model of measuring shield machine's position and orientation based on total station and laser target is introduced. The central coordinates of the cutter head and tail of shield machine are calculated through the three attitude angles of shield machine and the coordinate of laser target which is measured by total station.Secondly, a method of obtaining the horizontal angle of shield machine based on non-diffracting beam is studied, and in order to solve the spot center location problem in the measurement process, a novel center detection algorithm based on ring-filtering is developed. This algorithm firstly calculates the average light intensity in a circle, secondly figures out the sum of the absolute value of light intensity difference in this circle, then identifies the sum of the absolute value of light intensity difference in several circles as the objective function, so the center point is determined through the search of minimum value of the objective function using Nelder-Mead simplex method. Experimental results show that the positioning accuracy can reach 0.1 pixel.Thirdly, according to the measurement precision, research on error analysis and error allocation of measuring parameters of total station and electronic laser target is conducted. Sensibility analysis of each single parameter is performed based on interval calculation, and the compound error allocation is converted into a constrained optimal problem which is solved by Sequential Quadratic Programming using MATLAB. The allocation results proved by Monte Carlo method can be precision guidance to the instruments design, manufacture and selection of measurement system.Finally, research on the measurement site location of total station in the designed tunnel axis is conducted in this paper. The horizontal alignment and vertical alignment of the designed tunnel axis are studied, and then the visibility between total station and laser target is analyzed, lastly the model of total station transfer is established based on visibility constraint, angle constraint and length constraint. By this model, if the designed tunnel axis and three-dimensional model of shield machine is set, the measurement site location of total station will be identified in the pre-construction process, and the results can be guidance to the shield tunnel construction.Work of this dissertation paves the way for developing measurement and guidance system of shield machine.