Research On Fast Pyramid Angle Detection Method Of Helicopter Rotor Blades Based On PC104

Pyramid angle of helicopter rotor blades is an important working status parameter which directly affects the security, stability and comfort of the helicopter. It is significance to precisely measuring the pyramid angle in production and maintenance of helicopter. Aiming at deficiency of available methods mainly used to measure the pyramid angle on the rotor test bed and hardly accommodate airborne unmanned helicopter rotor blades pyramid angle measuring, an airborne helicopter rotor blade taper measurement system has been built based on PC104 and a deep research in fast pyramid angle measure method has been conducted in this paper.The primary work contents and achievements are as follows:(1) The system of helicopter rotor blade pyramid angle detection based on the PC104 has been built. According to the system performance index overall designed has been done.The system consists of hardware system and software system, the hardware system is made up of binocular stereo vision subsystem, embedded subsystem, lighting subsystem and upper computer subsystem;software system is made up of configuring software and real time pyramid angle measurement software which run on the PC104. The configuring software includes binocular camera management, real-time image preview, template image acquisition, stereo calibration, calibration result display which mainly achieve camera parameters configuration and stereo calibration which is time-consuming; the real time pyramid angle measurement software includes network communication, rotor blade image collection, cicular mark detection, cicular mark 3-D information calculation, pyramid angle measurement which mainly achieve airborne helicopter rotor blade pyramid angle measurement.(2) A fast circular marker location method in pyramid angle detection of helicopter rotor blades was proposed. Firstly, median filter and an intensifier named CLAHE were used to pre-process the image which contains the circular markers. Secondly, circular degree, inertia ratio and change rules of barycenter were used to locate the circular marker approximately. Finally, least square fitting method was used to locate the circular marker precisely.Through many circular mark location experiments under the emulated environments of pyramid angle detection in laboratory and real rotor blades blackground showed that the precision and time costs of the method was promoted in complex background and satisfy real-time airborne pyramid angle detection requirements.(3) An airborne pyramid angle detection method of helicopter rotor blades is studied. Firstly, configuring software was used to calibrate and rectify the binocular stereo vision system and transmit the intrinsic and extrinsic parameters to the pyramid angle measurement software based on PC104 through the network. Secondly, a rectified binocular stereo vision system was used to collected to rotor blades images which contains circular marks at the same location and the fast circular marker location method proposed in this paper was used to locate the mark center, on the basis of decode and match the circular mark 3-D information is calculated. Finally, used the circular mark 3-D information on different rotor blades to calculate the pyramid angle.Through the rotating rotor blades pyramid angle measurement experiments shows that the value of the pyramid angle consistent with the actual situation while the error of circular mark 3-D information measurement is less than 3.3mm and can meet the precision requirements of unmanned helicopter rotor blades pyramid angle detection system.