Research On Calibration Method Of Non-orthogonal Theodolite Measurement System And Correction Technique Of Sight Axis Parameters

The theodolite measurement system has several advantages.For example,it can measure coordinates with high precision without contacting the surface of the object.Also,the measurement system can be established easily.Due to these advantages,it is widely used in ship building,measuring the coordinate of a single point and other related fields.However,the traditional theodolite measurement system requires the user to aim the target point,which leads to a decrease in measurement efficiency.Recently,researchers tried to realize automatic measurement with vision guidance.With the high cost of the traditional theodolites,the automatic measurement system is very expensive.Besides,the measurement precision varies with the measurement distance.The recently proposed theodolite with non-orthogonal axes(N-Theodolite)makes it possible to solve these problems.N-Theodolite doesn’t require the three axes to satisfy the geometry constraints that any two of the axes should be orthogonal and the three axes should intersect at one point.Without the geometry constraints,the manufacturing cost of the N-Theodolite would decrease greatly.More importantly,with the replacement of telescope by the collimated laser,the measurement precision would not change with the measurement distance.Since the N-Theodolite is made without the geometric constraints,the mathematical model of it is more complex and new method to calibrate the measurement system is needed.At the same time,compared to the traditional theodolite,the parameters of the N-Theodolite can vary more easily,which makes it necessary to develop techniques to correct the parameters of the axes.We have done the following work to solve the aforementioned problems:1.Established the mathematical model of N-Theodolite based on its special structure.The parameters of the N-Theodolite measurement system are divided into intrinsic parameters and extrinsic parameters.Based on the model,the calibration method is proposed.2.To verify the calibration method and lay the foundation for future research on N-Theodolite,a software to simulate the N-Theodolite is developed.3.A technique based on forward intersection of N-Theodolites to correct the sight axis parameters is proposed.Several other correction techniques are also explored.4.The measurement software which can be used to calibrate the intrinsic and the extrinsic parameters is also developed.The software can measure the coordinate of a point in space.5.Simulation and experiments are conducted to verify the proposed calibration method and correction technique.