iPhone - Motion Core (Rotación relativa)

Question

¿Hay alguna manera de obtener una rotación relativa del movimiento del núcleo?

Lo que necesito es: cuánto giró en un eje y qué dirección (+ sign= en sentido antihorario, -= en el sentido de las agujas del reloj, de acuerdo con la regla de la derecha).

He encontrado la propiedad RotationRate, pero ahora estoy seguro de cómo me sacaría el ángulo, ya que esto me está dando radianos por segundo.

He hecho todo tipo de cosas en los últimos días, pero nada me está dando valores estables.He intentado realizar una muestra cronometrada de datos de movimiento central, usando un NSTIMER y calcule la diferencia entre dos muestras, por lo que tendría lo mucho que giró desde la última muestra, pero de tiempos a veces me da números locos como 13600 gradosIncluso cuando el iPhone está descansando sobre la mesa.

¿Alguna idea de cómo se puede lograr esto?

gracias

Answer 1

There is indeed. You can get what you're looking for by drilling down into the properties of CMMotionManager, through CMDeviceMotion and finally to CMAttitude. The attitude of the device is defined as:

the orientation of a body relative to a given frame of reference.

In the case of DeviceMotion's CMAttitude, that frame of reference is established by the framework when starting device motion updates. From that point in time on, the attitude of the device is reported relative to that reference frame (not relative to the previous frame).

The CMAttitude class provides some handy built in functionality to convert a CMAttitude to a form that is actually useful for something, like Euler Angles, a rotation matrix, or a quaternion. You sound like you're looking for the Euler Angle representation (Pitch, Yaw, Roll).

Answer 2

The answer provided above isn't quite accurate, though it's probably sufficient to answer this question. Core Motion tries to determine the device's absolute attitude at all times, meaning that the definition of the axes can vary depending on the device's orientation. For example, if the device is face-up, then pitch up/down is a rotation about the y-axis, but if the device is in landscape orientation, then pitch is a rotation about the z-axis (perpendicular to the plane of the screen). This is somewhat helpful if your application will only be used in one orientation, or you want a delta like the question asked for, but makes it excessively complicated if you want to know absolute orientation.