崔帅华, 余磊, 朱俊卿, 姚天, 熊邦书, 欧巧凤. 基于透视变换的直升机桨根扭转角测量方法[J]. 应用光学, 2023, 44(2): 412-419. DOI: 10.5768/JAO202344.0203008
引用本文: 崔帅华, 余磊, 朱俊卿, 姚天, 熊邦书, 欧巧凤. 基于透视变换的直升机桨根扭转角测量方法[J]. 应用光学, 2023, 44(2): 412-419. DOI: 10.5768/JAO202344.0203008
CUI Shuaihua, YU Lei, ZHU Junqing, YAO Tian, XIONG Bangshu, OU Qiaofeng. Measurement method of helicopter blade root torsion angle based on perspective transformation[J]. Journal of Applied Optics, 2023, 44(2): 412-419. DOI: 10.5768/JAO202344.0203008
Citation: CUI Shuaihua, YU Lei, ZHU Junqing, YAO Tian, XIONG Bangshu, OU Qiaofeng. Measurement method of helicopter blade root torsion angle based on perspective transformation[J]. Journal of Applied Optics, 2023, 44(2): 412-419. DOI: 10.5768/JAO202344.0203008

基于透视变换的直升机桨根扭转角测量方法

Measurement method of helicopter blade root torsion angle based on perspective transformation

  • 摘要: 现有方法常将相机从下至上拍摄标记物图像,当桨叶扭转幅度较大时,相机主光轴与标记物平面法向量存在明显夹角,导致拍摄图像存在透视畸变现象,从而引发较大测量误差。为解决上述问题,提出一种基于透视变换的直升机桨根扭转角测量方法。首先,将靶标垂直固定在桨叶下方,相机正对桨毂拍摄图像。其次,计算桨叶在低速拉平状态下待测方位与正方位靶标图像中的四个顶点坐标,并求解待测方位的透视变换矩阵,然后利用透视变换矩阵对桨叶高速运动状态下待测方位拍摄的畸变图像进行校正。最后,求得基准图像与校正后图像中的圆心坐标,进而计算出待测方位扭转角。实验结果表明,各方位测量误差均小于0.2°。该方法不但测量精度高,而且具有多方位动态测量的优点,在直升机旋翼桨叶运动参数测量领域具有良好的应用前景。

     

    Abstract: In the existing methods, images of markers are often taken from bottom to top. When the blade is twisted greatly, there is an obvious angle between the principal optic axis of the camera and the normal vector of a marker plane, resulting in perspective distortion of the captured images, which leads to relatively large measurement errors. In order to solve the problem raised above, a method of measuring the torsion angle of helicopter blade root based on the perspective transformation was proposed. Firstly, the target was vertically fixed under the blades, so that the camera was directly facing the propeller hub to capture images. Secondly, the four vertex coordinates of the blades in the target images of azimuth to be measured and positive azimuth were calculated when operating at the low-speed leveling state, and the perspective transformation matrix of the azimuth to be measured was solved. Moreover, the perspective transformation matrix was used to correct the distorted image of the azimuth to be measured under the high-speed motion state of the blades. Finally, the coordinates of the circle center in the reference image and the corrected image were obtained, and then the torsion angle of azimuth to be measured was calculated. The experimental results show that the measurement error of each azimuth is less than 0.2°. This method not only has high measurement accuracy, but also has the advantages of multi-azimuth dynamic measurement, which has a good application prospect in the field of motion parameters measurement of helicopter blade root.

     

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