Research On Fast Measurement Method Of Helicopter Rotor Blade Lead-lag Angle Based On CUDA

Helicopter rotor motion parameters is not only a very important performance evaluation in rotor design phase, but also important item in the routine maintenance, direct influence on the safety and reliability of helicopter. In order to solve the time-consuming and low efficiency problem of helicopter rotor blade lead-lag angle measurement based on CPU algorithm, fast method for helicopter rotor lead-lag angle measurement based on CUDA(compute unified device architecture) is studied by using the advantage of the GPU parallel computing. The main research contents and results are as follows:(1) The fast measurement system for helicopter rotor lead-lag angle based on CUDA has been build, including hardware subsystem and software subsystem. Hardware subsystem includes PC, Cameralink camera, Cameralink image grabber, frequency multiplier, and LED light source, functional modules and the selection of major device is analyzed according to all kinds of technical indexes of measurement system for helicopter rotor Lead-lag angle; Software subsystem includes rotor image acquisition, camera calibration, image preprocess, fast coded target detection based on CUDA, decoding and matching, lead-lag angle measurement, and design software development framework of lead-lag angle measurement, using program realized each software module.(2) A fast method of coded target detection based on CUDA is proposed. Firstly, the parallel algorithms of the most time-consuming parts in the flapping angle measurement:image denoising,threshold segmentation,connected component labeling,edge detection was studied; Secondly, a large number of intensive operations parallel implemented on different image processing units by using multi-level parallel strategies, Using the Shared memory and Shared registers to accelerate access to data; Finally, The results of different rotor blade image tests show that the operative efficiency of the method is obviously improved compared with the CPU algorithm. It can meet the requirements of fast measurement for helicopter rotor lead-lag angle.(3) A method of helicopter rotor Lead-lag angle measurement is proposed. Firstly, binocular camera has been calibrated by using the Zhangs calibration method; Secondly, helicopter rotor image has been collected,coded target is detected, decoded and matched; Thirdly, all the target 3D coordinates has been calculated; Finally, According to the definition, rotor blade lead-lag angle is measured in the rotor coordinate system. Experimental results show that the error of coded target 3D measurement is less than 2 mm. The lead-lag angle is stable,and the method is high efficiency and high accurateness.