DJI_FC_SUBSCRIPTION_TOPIC_HARD_SYNC wrong heading

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Rinto
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Hey! I know encountered two times that from the DJI_FC_SUBSCRIPTION_TOPIC_HARD_SYNC topic gives me a quaternion that the drone faces exactly north. Ones this was already on ground, ones this was just after takeoff. In both cases, the drone was not facing north.

I have a few questions:
- This is only a problem for us since the p1 only gives it's heading WRT north. If we could just obtain the encoder values, there would be absolutely no need for us to know where north is... Can you provide a method to give that to us?

- How do you compute the heading? Do you use GPS too? This is important for us to start debugging the problem: Why does it happen now? We are in gps-denied environment, possibly with gps repeaters spreading fake gps data.

- Would calibrating compasses regularly mitigate this problem?

 

It has happened both with the OSDK (latest version) as well as the PSDK (latest version), so I don't expect the problem to be in the SDK.

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  • LIPING.ZHOU

    DJI_FC_SUBSCRIPTION_TOPIC_HARD_SYN refers to hardware clock synchronization, not quaternions. DJI_FC_SUBSCRIPTION_TOPIC_QUATERNION is for quaternions. Could you please rephrase your question?

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  • Rinto

    My question is why sometimes the heading in this quaternion is indicating that the drone is exactly facing north, while in fact it is not.

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  • Rinto

    Any update? My message is waiting for approval but the hardsync data holds a quaternion.

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  • DJI Developer Support
    Dear Developer, Hello and thank you for reaching out to DJI Innovations. What firmware version is your drone using? We hope that our solution meets your needs satisfactorily. We appreciate your email and wish you a wonderful day! Best Regards, DJI Innovations SDK Technical Support Team
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  • Rinto

    We encountered this both on v10.01.08.01 as well as one version earlier (not sure which one that was).

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  • DJI Developer Support
    Dear Developer, Hello and thank you for reaching out to DJI Innovations. This TOPIC does not require a GPS environment and does not integrate GPS data; it mainly relies on the IMU. Are you experiencing inaccurate quaternion data? Could you please provide the PSDK debug logs and flight logs for us to review? We hope that our solution meets your needs satisfactorily. We appreciate your email and wish you a wonderful day! Best Regards, DJI Innovations SDK Technical Support Team
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  • Rinto

    I will extract PSDK debug logs next time I encounter this issue. Good to know that no GPS fusion is performed.

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  • DJI Developer Support
    Dear Developer, Hello and thank you for reaching out to DJI Innovations. OK， I'm always here to provide technical support whenever you need it. We hope that our solution meets your needs satisfactorily. We appreciate your email and wish you a wonderful day! Best Regards, DJI Innovations SDK Technical Support Team
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