Custom Follow Me Mission DJI Android SDK

问题

I am trying to create a FollowMeMission using the DJI Phantom 4 by providing custom coordinates, similar to this post Custom coordinates on Follow me Mission DJI Mobile SDK for android

My current code looks like this:

private double lat = 48.5561726;
private double lng = 12.1138481;
private float initHeight = 10f;
private LocationCoordinate2D location;

    if (getFollowMeMissionOperator().getCurrentState().toString().equals(FollowMeMissionState.READY_TO_EXECUTE.toString())){
        getFollowMeMissionOperator().updateFollowingTarget(new LocationCoordinate2D(lat + 0.0001d, lng), new CommonCallbacks.CompletionCallback() {
            @Override
            public void onResult(DJIError djiError) {
                setResultToToast("Mission updateFollowingTarget: " + (djiError == null ? "Successfully" : djiError.getDescription()));
            }
        });
        //Toast.makeText(getApplicationContext(), "updateFollowingTarget...", Toast.LENGTH_SHORT).show();
        Log.println(Log.INFO,"FOLLOW", "Before");

        try{
            Thread.sleep(2500);
        }catch (InterruptedException e){
            setResultToToast("InterruptedException!" + e.getMessage());
        }

        getFollowMeMissionOperator().startMission(FollowMeMission.getInstance().initUserData(lat + 0.0001d , lng, initHeight), new CommonCallbacks.CompletionCallback() {
            @Override
            public void onResult(DJIError djiError) {
                setResultToToast("Mission Start: " + (djiError == null ? "Successfully" : djiError.getDescription()));
            }});
    }
    else{
        Toast.makeText(getApplicationContext(), getFollowMeMissionOperator().getCurrentState().toString(), Toast.LENGTH_SHORT).show();
    }

I even added a 2.5 sec sleep before calling startMission() as advised in this topic http://forum.dev.dji.com/thread-33716-1-1.html

What happens is, i invoke FollowMe() and after 2.5 sec i get the message "Mission Start: Successfull", but without any callback from updateFollowingTarget(). Then nothing happens, the drone stays where it is.

What am i doing wrong? Is the way i use updateFollowingTarget() and startMission() even right?

回答1:

The causes on this issue are: 1. We need use timer to updateFollowingTarget in a given frequency. 2. The moving object (following target) need provide its dynamic location.
Please refer to below code to refine it for your case:

private float initHeight = 10f;
private LocationCoordinate2D movingObjectLocation;
private AtomicBoolean isRunning = new AtomicBoolean(false);
private Subscription timmerSubcription;
private Observable<Long> timer =Observable.timer(100, TimeUnit.MILLISECONDS).observeOn(Schedulers.computation()).repeat();

private void followMeStart(){
    if (getFollowMeMissionOperator().getCurrentState().toString().equals(FollowMeMissionState.READY_TO_EXECUTE.toString())){
        //ToDo: You need init or get the location of your moving object which will be followed by the aircraft.

        getFollowMeMissionOperator().startMission(FollowMeMission.getInstance().initUserData(movingObjectLocation.getLatitude() , movingObjectLocation.getLongitude(), initHeight), new CommonCallbacks.CompletionCallback() {
            @Override
            public void onResult(DJIError djiError) {
                setResultToToast("Mission Start: " + (djiError == null ? "Successfully" : djiError.getDescription()));
            }});

        if (!isRunning.get()) {
            isRunning.set(true);
            timmerSubcription = timer.subscribe(new Action1<Long>() {
                @Override
                public void call(Long aLong) {
                    getFollowMeMissionOperator().updateFollowingTarget(new LocationCoordinate2D(movingObjectLocation.getLatitude(),
                                                                                                movingObjectLocation.getLongitude()),
                                                                       new CommonCallbacks.CompletionCallback() {

                                                                           @Override
                                                                           public void onResult(DJIError error) {
                                                                               isRunning.set(false);
                                                                           }
                                                                       });
                }
            });
        }
    } else{
        Toast.makeText(getApplicationContext(), getFollowMeMissionOperator().getCurrentState().toString(), Toast.LENGTH_SHORT).show();
    }

}

来源：https://stackoverflow.com/questions/48404526/custom-follow-me-mission-dji-android-sdk