Research On Lead-Lag Angle Measurement System Of Helicopter Rotor Blade Based On Four-View Stereo Vision

Helicopter rotor blade motion parameters measurement is directly related to the safety of the helicopter,comfort,reliability,and the accuracy of the weapon system,helicopter development,the production and use of maintenance is the important project examination,the whole process is accompanied by the development of the helicopter,rotor blade-lag angle is one of the helicopter rotor motion parameters of vibration.This thesis,four-view stereo vision measurement techniques are used to study the measurement of helicopter rotor lead-lag angle.The main work contents and research results of this thesis are as follows:(1)This thesis,the research and development of the helicopter rotor Angle measurement system based on the four-view stereo vision is improved to improve the stability and reliability of the system in the real environment.On the hardware side,the improved camera triggers the input signal interface and overcomes the phenomenon that the camera is not synchronized in the original system.Increase the remote control computer,improve the safety of the field operator.In the aspect of software,the interface process operation is optimized to facilitate the dynamic setting of parameters.Optimized the camera calibration and 3d measurement code,improved the system robustness.After field test,the stability and reliability of the system are verified.(2)The detection method of marker point was studied.In view of the problem of the detection of the mark point in the blade image in the high speed under-exposure environment,a method of marker point detection based on CLAHE image enhancement is studied.First,the CLAHE reduction coefficient is set to adjust the enhancement effect.Secondly,using the CLAHE function provided by OpenCV library for image enhancement;Thirdly,the EDPF method is used to detect the contour of the marker.Finally,using the adaptive threshold CIC method to filter the contour of the circular marker.This thesis,a large number of blade marker images are tested in the field environment,and the validity of the method is verified for the detection of the marker points in high speed underexposure environment.(3)The matching method of marker points is studied.In order to solve the problem that the traditional matching method has poor anti-interference,and the failure to identify the partial marker points,a matching method based on the inner matrix circle is proposed.Firstly,according to the arrangement of the inner matrix circle,we find the inner matrix circle that satisfies the condition.Then,according to the location of the inner matrix circle,the guide circle is found,and the marking points are sorted.At last,the method of least square method is used to locate the defect.Through the matching test of the target and blade markers in a large number of field environments,it is proved that this method has strong anti-interference in the presence of interference and complex background environment.(4)The measurement method of helicopter rotor lead-lag angle based on four-view stereo vision is proposed.First,the four-view stereo vision system is synchronized to collect all azimuth's blade images,and the image is corrected and enhanced.Secondly,the image is marked point detection and mark point matching operation,and the 3d coordinates of the mark points are calculated according to the parallax principle.Then,the two sets of camera coordinates are converted to the same coordinate system using the total station.Finally,the rotor coordinate system is established,and the rotor angle is calculated according to the calculation formula of the lead-lag angle.After a large number of rotor measurement experiments,it is verified that the measurement of lead-lag angle proposed in this thesis is effective and has high accuracy.