CMDeviceMotion返回磁场的0值 [英] CMDeviceMotion returns 0 values for magnetic field

问题描述

我正在开发具有罗盘功能的iOS应用程序。我曾尝试使用 CMMagnetometerData 更新，这些更新会产生未校准但正常的结果。

I am developing iOS app with compass functionality. I have tried to use CMMagnetometerData updates which give uncalibrated, but normal results.

之后我试图获得 CMDeviceMotion 更新，结果总是给出零磁场 CMMagneticFieldCalibrationAccuracyUncalibrated 准确性。我唯一的设备是iPad，因此无法测试其他设备。

After that I tried to get CMDeviceMotion updates which turned out to give always zero magnetic field with CMMagneticFieldCalibrationAccuracyUncalibrated accuracy. The only device I have is an iPad, so can't test on others.

由于传感器未校准，但可能是场为零，但我找不到任何方法进行校准。

May be field is zero because sensor is not calibrated, but I could not find any way to perform calibration.

如何解决这个问题？

更新：

这里使用 startDeviceMotionUpdatesUsingReferenceFrame：toQueue：withHandler：，但它对我不起作用。

Here is suggested to use startDeviceMotionUpdatesUsingReferenceFrame:toQueue:withHandler:, however it didn't work for me.

这里建议将 showsDeviceMovementDisplay 设置为 true 。然而它也没有用，校准窗口就不会弹出。

Here is suggested to set showsDeviceMovementDisplay to true. However it didn't work either, calibration windows is just not popping up.

最后，已解决。根据我的观察：

Finally, SOLVED. According to my observations:

1）使用 startDeviceMotionUpdatesUsingReferenceFrame：toQueue：withHandler： with referenceFrame 不等于 allZeros 或 XArbitraryZVertical 。

1) Use startDeviceMotionUpdatesUsingReferenceFrame:toQueue:withHandler: with referenceFrame NOT equal to allZeros or XArbitraryZVertical.

2）将 showsDeviceMovementDisplay 设置为 true 。

经过几次零值更新，精确度 CMMagneticFieldCalibrationAccuracyUncalibrated 它会正常化。

After few zero-value updates with accuracy CMMagneticFieldCalibrationAccuracyUncalibrated it will normalise.

代码：

...
motionManager.deviceMotionUpdateInterval = 0.05
motionManager.showsDeviceMovementDisplay = true 
motionManager.startDeviceMotionUpdatesUsingReferenceFrame(CMAttitudeReferenceFrame.XArbitraryCorrectedZVertical, toQueue: NSOperationQueue.mainQueue(), withHandler:handleUpdate)
...
private func handleUpdate(data: CMDeviceMotion!, error: NSError!) {
    if data != nil {
        let field = data.magneticField.field
        println("\(field.x), \(field.y), \(field.z)")
    }
}

推荐答案

最后，根据我自己的观察：

Finally, according to my own observations:

1）使用 startDeviceMotionUpdatesUsingReferenceFrame：toQueue：withHandler： with referenceFrame 不等于 allZeros 或 XArbitraryZVertical 。

1) Use startDeviceMotionUpdatesUsingReferenceFrame:toQueue:withHandler:with referenceFrame NOT equal to allZeros or XArbitraryZVertical.

2）设置 showsDeviceMovementDisplay 到 true 。

经过几次零值更新，准确度 CMMagneticFieldCalibrationAccuracyUncalibrated 它会正常化。

After few zero-value updates with accuracy CMMagneticFieldCalibrationAccuracyUncalibrated it will normalise.

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