Research On The Key Technologies Of Automatic Directional Aiming System

The directional aiming system(DAS)is an azimuth measurement system consisting of a north finding system with directional function and a collimation theodolite system with aiming function.The DAS is used to measure the angle between the specific target and the north direction,and it is widely used in mining,tunnel excavation,mapping,military and other fields.However,the current DAS is in low level of automation,and it needs manual leveling,manual aiming and manual calculation during the working process,so it fails to meet the modern measurement requirement of automation and rapidness.Therefore,it is of great significance to establish the mathematical model of the DAS,research on the key technologies of automatic DAS(ADAS),construct the integrated DAS,so that the system is capable of automatic leveling,automatic north finding and automatic aiming.In order to realize the ADAS,this paper establishes the mathematical model of the automatic leveling of the rotating shaft,the scheme of strap down north finding and the automatic aiming of collimation theodolite.The simulation and experimental verification of each mathematical model are carried out,and their influence on the measurement accuracy and automatic measurement time of the DAS is obtained.The main research work and results of this paper are as follows,1.The mathematical model of measuring the rotation axis tilt based on a dual inclinometer is established.The model greatly decreases the influence of the temperature drift of the inclinometer,and it is suitable for the measurement of the rotation axis tilt with various sizes and smoothness.Based on the tilt and the high point fixed leveling strategy,the angle closed loop method is used to adjust the tilt angle of the rotation axis,which overcomes the influence of stepping motor out of step and external disturbances.After the automatic leveling is completed,the accuracy of the automatic leveling is checked using a high precision electronic level indicator.2.The mathematic model based on a rate gyroscope strap down north finding scheme is established.The model describes the relationship between the output of the gyroscope,the random error and zero drift of the gyro,the installation error of the gyro,the installation error of the rotation axis,the number of index points,the accuracy of the encoder and the working latitude.According to the mathematical model and the error transfer theory,the influences of the system parameters and the installation errors on the north finder accuracy are obtained.The relationship of north finding accuracy against automatic north finding time is discussed.Therefore,the user can select the appropriate gyro and encoder and determine the installation accuracy of the gyro and the rotation axis according to the system design requirements and the mathematical model.Meanwhile,the balance between the north finding precision and the automatic north finding time can be determined.3.The mathematic model of aiming the target using collimation theodolite is established.An automatic aiming strategy is proposed,which first quickly finds the target(coarse aiming)over a wide range,then aims the target precisely over a small range(fine aiming),and finally moves the laser spot to the CCD zero position.According to the size of the tilt of the cooperative target,the aiming models of keeping the guide rail unmoved and moving the guide rail are introduced.The method of calibrating the collimation theodolite using the right angle prism and the multi-tooth indexing table is proposed,which eliminates the influence of the system error and improves the measurement accuracy.4.The north finder and collimation theodolite are installed in the same base to construct the DAS?The calibration scheme of the angle between the north finding system and the collimation theodolite system is proposed.The calibration and precision test experiemnts are conducted based on the prototype.The DAS plays a very important role in civil and military fields.This paper studies the mathematical model of the automatic measurement of the DAS,and puts forward the calibration method of the system.The modeling and simulation analysis of the rotation axis automatic leveling technology,automatic north finding and collimation-theodolite automatic searching and aiming are carried out,which provide an important theoretical basis for the design of high precision ADAS.At the same time,this paper has completed the production of the system prototype,which has laid the foundation for the use and popularization of the ADAS.