| The flapping angle of helicopter rotor blade is an important parameter to verify the rotor manufacturing process and reflect the rotor working state,this parameter impacts on the safety and stability of the helicop ter directly,it’s precision measurement is important for helicopter maintenance and production.To solve the existing problem that the helicopter rotor blade flapping angle measure system based on Binocular vision is limited by the size of lens field,resolution and the self-occlusion of measurement,a helicopter rotor blade flapping angle measurement system was developed by using the four-view stereo vision technology,The main research contents and results are as follows:(1)A helicopter rotor blade flapping angle measure system based on the four-view stereo vision technology has been designed.According to the demand analysis,the hardware and software design of the flapping angle measuring system was carried out,the hardware and software debugging was completed.In the hardware system,the selection of camera,image acquisition card,PC,frequency multiplier,total station and light source and other hardware equipment is completed,according to the requirements of the technical indicators.In software system,the overall design of software is completed according to the requirements of system.The software mainly includes the function modules such as equipment management,image collection,four-view stereo vision calibration,targets 3D coordinates calculation and calculation of flapping angle,the function of the modules is achieved by using Visual Studio 2010.After hardware and software debugging,the measurement system this paper designed can meet user needs.(2)A four-view stereo vision calibration method based on total station is realized.Firstly,the four-view stereo vision is divided into two groups of binocular stereo vision,and complete the calibration;Secondly,the checkerboard is placed in two groups of binocular stereo visual field,and collect checkerboard image,and calculate 3D coordinates of the corner point in the total station coordinate system;Finally,the relationship between the two coordinate systems can be calculated by using the camera coordinate system and the 3D coordinates of the corner point in the total station coordinate system,the two groups of binocular stereo vision coordinate system are calibrated into the total station coordinate system by using the relationship between the coordinate system,then the four-view stereo vision calibration is completed.Through the real four-view stereo vision calibration experiment,the results show that the proposed method has high calibration accuracy and can have a practical utilization in research on helicopter rotor flapping angle measurement.(3)This paper proposes a method of measuring the flapping angle of blade based on four-view stereo vision.Firstly,four-view stereo vision is used to collect the image pairs of blade with markings in different direction,and two groups of binocular stereo vision take 180°of the blade trajectory plane respectively;Secondly,the coordinates of the marker points in the binocular stereo coordinate system are calculated by image correction,marker point detection,marker point matching and binocular stereo calibration,and the 3D coordinates of the marker points in the total station coordinate system are calculated by the result of four-view stereo vision calibration;Thirdly,the rotor coordinate system is calculated by using the 3D coordinates of the marker points in the total station coordinate system,and the 3D coordinates of the total station coordinate system are transformed into the rotor coordinate system;Finally,according to the flapping angle formula,the blade flapping angle is calculated using the 3D coordinates in the rotor coordinate system.Making the experimental of flapping angle by using rigid blades to simulate the helicopter rotor blades,the results show that this method can have a practical utilization in research on helicopter rotor flapping angle measurement. |
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