I’m part of an undergraduate robotics research group in my university that’s currently trying to develop an autonomous drone. I’m reaching out to seek your expertise regarding an issue we’re encountering with our drone’s flight stability.
The Problem
We’re experiencing persistent pitch and roll oscillations while attempting to fly our drone in the Stabilize, Alt-Hold, and Loiter flight modes. The oscillations are mainly perceived when the vehicle is stationary. Even though the quad is still flyable, these issues cause AutoTune attempts to fail, indicating the error message “failing to level, manual tune may be required”. We suspect that the unfavorable wind conditions during our testing might have contributed to these failures, but the oscillations are still perceived indoors.
Our Troubleshooting Efforts
We meticulously followed the First Flight and Tuning guidelines, but we encountered challenges in assessing the effectiveness of Notch Filter and In-Flight FFT configurations. Also, we were compelled to reduce PID values by 50% on two separate occasions to enable the drone to lift off. Subsequently, we proceeded with the Manual Tuning process outlined in the wiki and reached a flyable configuration described above. We also checked for accelerometer vibrations and they seem to be okay.
Our Objective
Our primary goal is to achieve stable flight with minimal oscillations.
Drone Specifications:
Airframe: Share Goo F450 4-Axis Multi Rotor Airframe 450mm
Motors: iFlight XING2 3110 Cinelifter Motor - 900KV
Propellers: HQProp MacroQuad 9x5x3 Propellers
ESCs: V-Good RC 32-Bit 80A 2-6S ESC
Flight Controller: Pixhawk 6X Mini
Holybro M9N GPS Module
Radio Receiver: Frsky Archer M+ Access SBus Full Range 16/24 Channels
Copter 4.4.4
Additional Notes
We hypothesize that the outdated PWM protocol of the ESCs and potential mechanical inconsistencies might be influencing the tuning quality. We addressed a video, pictures and logs of the drone here.
We would be immensely grateful for any insights or suggestions you might have to address this issue and achieve our desired flight stability. Your collective expertise is invaluable to our progress.
Agradeço suas boas-vindas! Eu e um colega de equipe fizemos uma revisão das seções 1 e 2 do guia e identificamos algumas áreas em que nossa configuração atual não está em conformidade:
1.1 - Nosso frame não é feito de fibra de carbono, embora não acreditemos que isso seja crucial.
1.2 - Estamos usando uma ESC com protocolo PWM, que não suporta telemetria de RPM.
1.3 - Suspeitamos que nossas hélices e motores podem não estar adequadamente balanceados.
1.4.1 - Não implementamos uma montagem de FC que amortece as vibrações.
1.4.2 - Nossa configuração atual não segue estritamente a orientação para separar o compass dos caminhos de alta corrente.
1.4.3 - Não protegemos o barômetro com nenhum material em nossa configuração atual.
1.5 - Nosso gerenciamento de cabos poderia ser melhorado.
1.11 - É provável que os motores do nosso drone não estejam perfeitamente alinhados.
2.1 - Não realizamos a calibração de temperatura da IMU.
2.6 - Nossa ESC não suporta completamente o processo descrito.
2.11 - Não executamos esse procedimento.
2.12 - Também não executamos esse procedimento.
Com base nesses pontos, gostaríamos de sua opinião sobre quais são os mais prováveis de causar as instabilidades de voo que estamos experimentando. Planejamos implementar os processos descritos no guia ao longo da próxima semana e forneceremos atualizações à medida que avançamos.
Agradecemos antecipadamente por seu tempo e colaboração!
EN
Thank you for your warm welcome! My teammate and I have reviewed sections 1 and 2 of the guide and identified several areas where our current setup does not comply:
1.1 - Our frame is not made of carbon fiber, although we do not believe this to be crucial.
1.2 - We are using an ESC with a PWM protocol, which does not support RPM telemetry.
1.3 - We suspect that our propellers and motors may not be properly balanced.
1.4.1 - We have not implemented an FC mount that dampens vibrations.
1.4.2 - Our current setup does not strictly follow the guidance to separate the compass from high current paths.
1.4.3 - We have not protected the barometer with any material in our current setup.
1.5 - Our cable management could be improved.
1.11 - It is likely that the motors of our drone are not perfectly aligned.
2.1 - We have not performed IMU temperature calibration.
2.6 - Our ESC does not fully support the described process.
2.11 - We have not performed this procedure.
2.12 - We have also not performed this procedure.
Based on these points, we would like your opinion on which are most likely to cause the flight instabilities we are experiencing. We plan to implement the processes described in the guide over the next week and will provide updates as we progress.
We thank you in advance for your time and collaboration!