Okay, we had some successful tests that day.
Before the test, I asked CH and Shawn to exchange the OEM4 and OEM5 which were installed on SWAN and H-LING, respectively. Therefore, at the beginning of the test, SWAN was equipped with OEM5, and something wrong during the flight. We found the onboard PA gave abnormal information, and of course SWAN couldn't perform normal heading tracking flight. At first, we thought the problem was due to the complementary filter which had not been tested onboard before. However, after turning off the complementary part, the PA still exhibited strange results. Then, we put the OEM4 back instead of the OEM5, everthing was okay! Therefore, we concluded that something not right with the OEM5.
With the complementary PA, SWAN had performed several not bad heading tracking and turning. It has been about two years since the previously autonomous flight of SWAN. The successful flight test made SWAN ``reborn.'' At least I feel so. :-)
Another good result is the PA of H-LING calculated onboard. The PA calculated in realtime matched the one by post-processing. So, it's the time to test the PA in the hovering control.
God bless H-LING.