| As the core part of power supply, aircraft engine is the most important part of airplane. In the aircraft assembly process, the aircraft engine installation work is also an important part. Due to the aircraft engine has a high weight, large volume, complex shape and small installation gap, its installation work is very difficult. At present, the domestic aircraft engine installation work is carried out by manual operation with hydraulic equipments, and we can’t adjust the engine accurately in this way. It not only costs a lot of manpower, but also can’t ensure the installation accuracy and efficiency. In order to solve the problems of poor accuracy and low efficiency in manual way, a lot of related researches at home and abroad are analyzed and according to the difficulties and requirements of the engine in the installation process, a design plan of aircraft engine digital installation system which is based on dual-CPU and can achieve the automated installation with the vision measurement system is proposed.The control system of the aircraft engine digital installation system is designed. The overall plan of the opening CNC system with dual-CPU based on "IPC+GALIL" is proposed. The main circuit and control circuit are designed. According to the need of real-time measurements of engine posture, a visual servo system based on position is designed and the structure and principle of the vision measurement system is produced. The hardware system is designed by taking electromagnetic compatibility into consideration. According to the special situations that may occur during installation process, some safety protection measures are proposed.According to the imaging principle of the visual system, the measurements algorithm of position and orientation of engine is given. Based on the analysis of geometric model of camera imaging, the radial symmetry transform of image of engine target is accomplished. A method of camera calibration through recovering the low rank matrix of pixel is proposed. And ALM is used to solve the optimization problem. The internal and external parameters of the camera are obtained to get the position and orientation of engine in the camera coordinate system.The kinematics analysis of CNC adjusting platform of the system is achieved and the forward kinematics and inverse kinematics of the lifting and tilting mechanism are obtained. The representation method of position and orientation in the space and method of coordinate transformation are given. According to the standard installation path of engine in the nacelle, the off-line trajectory planning is achieved by coordinate transformation. The on-line revising for off-line trajectory through visual measurements system is proposed. And the automated installation program is written.The experiment platform of engine installation is built to test and verify above-mentioned theoretical analysis. And the engine installation experiments are done to get the results and data and several factors which cause the installation errors are analyzed. The practice results show that, it can ensure the stability, efficiency and accuracy by using the digital installation system in this paper to install aircraft engines and the effect is significantly improved compared to the manual installation. |
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