An ObserVIEW user sought to fix a vibration issue with their drone before a competition. In practice, the drone wobbled left to right rather than flying on a straight track.
This drone could record up to 16MB of flash storage at 8kHz. So, the user recorded the flight data and opened the CSV file in ObserVIEW for analysis. The data did not include a sample rate, but the user could add a sample rate in the CSV import tool, which they knew to be 2,000Hz. The text import feature allows engineers to import nearly any text or CSV file into ObserVIEW, where they can define information like the waveform sample rate and channel units.
Text Import dialog in ObserVIEW. The user added a sample rate before importing the data into the software.
The initial data file had a lot of diagnostic data, but the user’s goal was to compare the RC command and the gyro to see how the two related. The RC command is the controller’s command to the drone; the gyro measures where the drone is pointing. When the controller gives a command, the drone should react and meet that command.
Comparison of RC command and gyro data.The top graph is pitch, the center graph is roll, and the bottom graph is yaw.
From the time-waveform graphs, the user determined that the drone’s pitch and roll had met the RC command, but the yaw (or turn) did not. They zoomed in on the oscillation in the yaw graph and applied a delta cursor to find the oscillation frequency (peak-to-peak), which was around 26Hz. Spectral analysis data verified the low-frequency oscillation.
Using the delta cursor to determine the frequency of the oscillation.
The oscillation was due to resonance in the frame and its transfer into the gyro chip. The user adjusted the gyro mounting and the electronic speed control settings. They changed the soft mounting of the flight control board to reduce the transmissibility between oscillations and resonance in the frame. In doing so, they were able to mitigate the shaking. Changing some settings on the electronic speed control tamped it down further.
The user confirmed that the changes improved the oscillation by comparing the data before and after.