The coupling error in the measurement of ship hull deformation can significantly influence the attitude accuracy of the shipborne weapons and equipments. It is therefore important to study the characteristics of the coupling error. In this paper, an comprehensive investigation on the coupling error is reported, which has a potential of deducting the coupling error in the future. Firstly, the causes and characteristics of the coupling error are analyzed theoretically based on the basic theory of measuring ship deformation. Then, simulations are conducted for verifying the correctness of the theoretical analysis. Simulation results show that the cross-correlation between dynamic flexure and ship angular motion leads to the coupling error in measuring ship deformation, and coupling error increases with the correlation value between them. All the simulation results coincide with the theoretical analysis.
The “Unity of Knowing and Doing” (UKD) theory is proposed by an ancient Chinese philosopher, Wang Shouren, in 1508, which explains how to unify knowledge and practice. Different from the Chinese traditional UKD theory, the international higher education usually treats knowledge and practice as independent, and puts more emphasis on knowledge. Oriented from the UKD theory, the College of Opto-electric Science and Engineering (COESE) at National University of Defense Technology (NUDT) explores a novel training model in cultivating opto-electric professionals from the aspects of classroom teaching, practice experiment, system experiment, design experiment, research experiment and innovation experiment (CPSDRI). This model aims at promoting the unity of knowledge and practice, takes how to improve the students’ capability as the main concern and tries to enhance the progress from cognition to professional action competence. It contains two hierarchies: cognition (CPS) and action competence (DRI). In the cognition hierarchy, students will focus on learning and mastering the professional knowledge of optics, opto-electric technology, laser, computer, electronics and machine through classroom teaching, practice experiment and system experiment (CPS). Great attention will be paid to case teaching, which links knowledge with practice. In the action competence hierarchy, emphasis will be placed on promoting students’ capability of using knowledge to solve practical problems through design experiment, research experiment and innovation experiment (DRI). In this model, knowledge is divided into different modules and capability is cultivated on different levels. It combines classroom teaching and experimental teaching in a synergetic way and unifies cognition and practice, which is a valuable reference to the opto-electric undergraduate professionals’ cultivation.
The combination of the strap-down inertial navigation system(SINS) and the celestial navigation system(CNS) is one of the popular measures to constitute the integrated navigation system. A star sensor(SS) is used as a precise attitude determination device in CNS. To solve the problem that the star image obtained by SS is motion-blurred under dynamic conditions, the attitude-correlated frames(ACF) approach is presented and the star sensor which works based on ACF approach is named ACFSS. Depending on the ACF approach, a novel device-level SINS/ACFSS deeply integrated navigation method is proposed in this paper. Feedback to the ACF process from the error of the gyro is one of the typical characters of the SINS/CNS deeply integrated navigation method. Herein, simulation results have verified its validity and efficiency in improving the accuracy of gyro and it can be proved that this method is feasible.
Lever arm effect has to be considered in transfer alignment technology. Between static lever arm and dynamic lever arm, the former has larger amplitude, and it is the major error source in transfer alignment. How to measure and solve it become an important problem. This paper takes vehicle as a rigid body. Assume that static lever arm does not change in a short time, based on two inertial measurement units(IMU), data are measured and constituted several matrixes properly. After that, by using least square method, static lever arm is solved finally. Simulation experiments are implemented, results show that static lever arm can be solved effectively. Further study shows that, the precision of the method can be improved by preprocessing low pass filter.
Ship deformation is the main error source of partial reference. Such deformation can be estimated by laser gyro units and Kalman filter technology. For Kalman filter, deformation was divide into two parts, dynamic deformation, and static deformation. Traditionally, dynamic deformation is treated as AR2 model .In this paper, dynamic deformation is taken as a kind of ARX model. Based on actual data measured by Yuanwang-3 Space Survey Ship, simulation experiments are studied. Results show that the novel model can improve the measurement precision.
Point array is proposed as the cooperated target to achieve the precise detection for rolling angle in an optical collimated path. The point array image is generated according to the rolling angle, and the algorithm for precise rolling angle detection is described. The factors which impact the detection error of the rolling angle are analyzed in detail. The results of numerical simulations indicated that sub-arcsecond precision detection for rolling angle is achieved by point array, which is superior to that attained by any other targets.
We present an optical method to measure three dimensional (3D) ship deformations. This method is based on optical
collimation theory and thereby, with a crosshairs image projected and captured in a collimation optical path, the 3D
deformation angles, including the pitching angle, the yawing angle and the rolling angle, could be calculated by image’
variation. In order to improve the measurement precision, sub-pixel location algorithm is adopted in image processing.
Particularly, given that the rolling angle is the most difficult to measure in a collimation optical path, numerical
simulation is carried out to analysis the error characteristics of this angular measurement. Experimental results indicate
that this 3D ship deformations measurement achieve the precision of several arcsecs in the distance of 25m and in the
deformation range of -120″~120″.
In order to validate the detection precision of a three Dimensions Optical Deformation Measure System (3D-OMS), a
calibration method of auxiliary coordinate and the optical coordinate base on theodolites has been proposed. The
installation method by using theodolites to calibrate the auxiliary coordinate and the optical coordinate has been
proposed. Specifically, after the auxiliary mirrors installed, the installation accuracy is detected, then we analyzed the
influence of Axis-Error of theodolite under the practical condition of our experiment. Furthermore, the influence of
validation precision for the 3D-OMS caused by the misalignment of auxiliary coordinate and optical coordinate is
analyzed. According to our theoretical analysis and experiments results, the validation precision of the 3D-OMS can
achieve an accuracy of 1″ at the conditions of the coordinate alignment accuracy is no more than 10′ and the measuring
range of 3D-OMS within ±3′. Therefore, the proposed method can meet our high accuracy requirement while not
sensitive to the installation error of auxiliary mirrors. This method is also available for other similar work.
The steam flow in low-pressure turbine contained abundant water droplets, which will decrease the work efficiency and
pose potential threaten to operation safety, so measurement of steam wetness has brought great interest in electricity
generation industry. In this paper, a new measuring method using CCD (Charge Coupled Device) imaging technique was
proposed to determine the wetness in steam turbine based on the forward small angle light scattering theory. A simulated
steam turbine facility was designed to generate the wet steam, and light scattering experiments were carried out at
various working conditions in this device. The steam wetness parameters and droplet size distribution were obtained by
means of numerical inversion of the light intensity distribution based on Mie scattering theory. The results demonstrate
that the obtained data from the present analysis is in good agreement with the results of the theory analysis and previous
study, and the proposed method is proved to be suitable for steam wetness measuring and monitoring by further