Question

我正在记录我在CADisplayLink回调中从CMMotionManager deviceMotion获得的“态度”值（我需要根据设备旋转执行动画）。

这些值似乎每隔几毫秒就会“抽搐”很多程度（高达30％）。这似乎有很多不稳定因素，让我想知道我做错了什么，或者它是否与设备有关。

请查看下面的日志。印刷的“角度”是“态度”的“滚动”部分，转换为度：

2013-04-10 00:07:12.683 MyApp[450:707] Angle: -92.91 2013-04-10 00:07:12.712 MyApp[450:707] Angle: -70.52 2013-04-10 00:07:12.714 MyApp[450:707] Angle: -92.25 2013-04-10 00:07:12.745 MyApp[450:707] Angle: -70.03 2013-04-10 00:07:12.747 MyApp[450:707] Angle: -91.74 2013-04-10 00:07:12.779 MyApp[450:707] Angle: -69.67 2013-04-10 00:07:12.784 MyApp[450:707] Angle: -91.23 2013-04-10 00:07:12.812 MyApp[450:707] Angle: -69.43 2013-04-10 00:07:12.815 MyApp[450:707] Angle: -91.19 2013-04-10 00:07:12.846 MyApp[450:707] Angle: -69.53 2013-04-10 00:07:12.849 MyApp[450:707] Angle: -91.33 2013-04-10 00:07:12.879 MyApp[450:707] Angle: -69.74 2013-04-10 00:07:12.881 MyApp[450:707] Angle: -91.57 2013-04-10 00:07:12.912 MyApp[450:707] Angle: -70.01 2013-04-10 00:07:12.915 MyApp[450:707] Angle: -91.85 2013-04-10 00:07:12.945 MyApp[450:707] Angle: -70.13 2013-04-10 00:07:12.949 MyApp[450:707] Angle: -91.99 2013-04-10 00:07:12.979 MyApp[450:707] Angle: -70.03 2013-04-10 00:07:12.983 MyApp[450:707] Angle: -91.93 2013-04-10 00:07:13.012 MyApp[450:707] Angle: -69.76 2013-04-10 00:07:13.016 MyApp[450:707] Angle: -91.71 2013-04-10 00:07:13.046 MyApp[450:707] Angle: -69.34 2013-04-10 00:07:13.051 MyApp[450:707] Angle: -91.19 2013-04-10 00:07:13.079 MyApp[450:707] Angle: -68.89 2013-04-10 00:07:13.082 MyApp[450:707] Angle: -90.94 2013-04-10 00:07:13.112 MyApp[450:707] Angle: -68.52 2013-04-10 00:07:13.114 MyApp[450:707] Angle: -90.66 2013-04-10 00:07:13.151 MyApp[450:707] Angle: -67.85 2013-04-10 00:07:13.156 MyApp[450:707] Angle: -89.47 2013-04-10 00:07:13.179 MyApp[450:707] Angle: -65.66 2013-04-10 00:07:13.181 MyApp[450:707] Angle: -88.10 2013-04-10 00:07:13.212 MyApp[450:707] Angle: -63.81 2013-04-10 00:07:13.216 MyApp[450:707] Angle: -86.33 2013-04-10 00:07:13.245 MyApp[450:707] Angle: -61.07 2013-04-10 00:07:13.248 MyApp[450:707] Angle: -83.63 2013-04-10 00:07:13.279 MyApp[450:707] Angle: -58.95 2013-04-10 00:07:13.282 MyApp[450:707] Angle: -81.46 2013-04-10 00:07:13.312 MyApp[450:707] Angle: -56.71 2013-04-10 00:07:13.314 MyApp[450:707] Angle: -79.06 2013-04-10 00:07:13.346 MyApp[450:707] Angle: -53.29 2013-04-10 00:07:13.350 MyApp[450:707] Angle: -75.23 2013-04-10 00:07:13.380 MyApp[450:707] Angle: -51.63 2013-04-10 00:07:13.383 MyApp[450:707] Angle: -73.37 2013-04-10 00:07:13.414 MyApp[450:707] Angle: -50.35 2013-04-10 00:07:13.418 MyApp[450:707] Angle: -72.11 2013-04-10 00:07:13.446 MyApp[450:707] Angle: -50.08 2013-04-10 00:07:13.450 MyApp[450:707] Angle: -72.01 2013-04-10 00:07:13.479 MyApp[450:707] Angle: -50.50 2013-04-10 00:07:13.488 MyApp[450:707] Angle: -73.51 2013-04-10 00:07:13.512 MyApp[450:707] Angle: -51.25 2013-04-10 00:07:13.514 MyApp[450:707] Angle: -74.14 2013-04-10 00:07:13.545 MyApp[450:707] Angle: -49.98 2013-04-10 00:07:13.547 MyApp[450:707] Angle: -72.96 2013-04-10 00:07:13.579 MyApp[450:707] Angle: -46.99 2013-04-10 00:07:13.582 MyApp[450:707] Angle: -68.58 2013-04-10 00:07:13.612 MyApp[450:707] Angle: -43.01 2013-04-10 00:07:13.616 MyApp[450:707] Angle: -65.32 2013-04-10 00:07:13.645 MyApp[450:707] Angle: -40.92 2013-04-10 00:07:13.647 MyApp[450:707] Angle: -62.80 2013-04-10 00:07:13.680 MyApp[450:707] Angle: -39.70 2013-04-10 00:07:13.683 MyApp[450:707] Angle: -61.30 2013-04-10 00:07:13.712 MyApp[450:707] Angle: -40.74 2013-04-10 00:07:13.714 MyApp[450:707] Angle: -63.06 2013-04-10 00:07:13.745 MyApp[450:707] Angle: -42.29 2013-04-10 00:07:13.747 MyApp[450:707] Angle: -65.68 2013-04-10 00:07:13.779 MyApp[450:707] Angle: -43.18 2013-04-10 00:07:13.780 MyApp[450:707] Angle: -67.58 2013-04-10 00:07:13.812 MyApp[450:707] Angle: -42.13 2013-04-10 00:07:13.815 MyApp[450:707] Angle: -66.35 2013-04-10 00:07:13.845 MyApp[450:707] Angle: -40.95 2013-04-10 00:07:13.848 MyApp[450:707] Angle: -64.67 2013-04-10 00:07:13.879 MyApp[450:707] Angle: -39.73 2013-04-10 00:07:13.881 MyApp[450:707] Angle: -62.90 2013-04-10 00:07:13.913 MyApp[450:707] Angle: -40.06 2013-04-10 00:07:13.916 MyApp[450:707] Angle: -63.12 2013-04-10 00:07:13.947 MyApp[450:707] Angle: -40.78 2013-04-10 00:07:13.949 MyApp[450:707] Angle: -63.39 2013-04-10 00:07:13.979 MyApp[450:707] Angle: -41.51 2013-04-10 00:07:13.981 MyApp[450:707] Angle: -62.78 2013-04-10 00:07:14.012 MyApp[450:707] Angle: -42.06 2013-04-10 00:07:14.014 MyApp[450:707] Angle: -61.77 2013-04-10 00:07:14.045 MyApp[450:707] Angle: -43.89 2013-04-10 00:07:14.047 MyApp[450:707] Angle: -61.02 2013-04-10 00:07:14.079 MyApp[450:707] Angle: -45.41 2013-04-10 00:07:14.080 MyApp[450:707] Angle: -61.20 2013-04-10 00:07:14.112 MyApp[450:707] Angle: -46.93 2013-04-10 00:07:14.114 MyApp[450:707] Angle: -61.53 2013-04-10 00:07:14.146 MyApp[450:707] Angle: -49.21 2013-04-10 00:07:14.147 MyApp[450:707] Angle: -62.76 2013-04-10 00:07:14.179 MyApp[450:707] Angle: -51.34 2013-04-10 00:07:14.182 MyApp[450:707] Angle: -64.51 2013-04-10 00:07:14.212 MyApp[450:707] Angle: -53.39 2013-04-10 00:07:14.214 MyApp[450:707] Angle: -66.41 2013-04-10 00:07:14.245 MyApp[450:707] Angle: -56.29 2013-04-10 00:07:14.248 MyApp[450:707] Angle: -69.30 2013-04-10 00:07:14.279 MyApp[450:707] Angle: -57.85 2013-04-10 00:07:14.280 MyApp[450:707] Angle: -70.88 2013-04-10 00:07:14.312 MyApp[450:707] Angle: -60.23

测量的角度每几毫秒“闪烁”几乎20度。根据我到目前为止读到的关于CoreMotion的内容，我期待错误，但不是这个范围。

我可能做错了什么 - 我不是在衡量正确的事吗？

编辑：下面的代码 - 抱歉格式化。 “code”和“blockquote”似乎都无法正常工作。

//在开始动作更新之前，我让用户稍稍休息一下。
//目前，这是一个天真的空闲计时器，之后被解雇
//启动应用程序的前9秒（正当理由）

- （void）didFireIdleTimer：（id）theTimer {

[mReferenceAttitude release];
mReferenceAttitude = [[[sSharedMotionManager deviceMotion]态度]保留];

[self stopIdleTimer];
}

// sSharedMotionManager是CMMotionManager的一个实例

//然后，我正在设置一个显示链接回调，其中“当前”的deviceMotion
每次检索//和当前“态度”之间的差异
//并参考“态度”计算。正是这种差异
//转换为度数并打印

//这是显示链接回调，懒洋洋地命名。 :)
- （void）didRefreshScreen：（id）sender {

CMAttitude * thisAttitude = [[sSharedMotionManager deviceMotion]态度];
[thisAttitude multiplyByInverseOfAttitude：mReferenceAttitude];

NSLog（@“Angle：％0.2f”，thisAttitude.roll * 180 / 3.14159）;

//其余代码
// ....
}

Answer 1

几小时的测试确认问题出现是因为deviceMotionUpdateInterval实例未设置CMMotionManager。将其设置为1.0/60.0（或任何其他有效值）可修复此“闪烁”并导致值平滑变化。

Answer 2

看看这些值，我注意到每一秒测量的系列似乎都没问题。这意味着1,3,5,7，......和2,4,6,8 ......是稳定的稳定序列。在大多数情况下，这表示正在运行2个实例或切换参考姿态。

Answer 3

这是我的代码，以避免在may app中闪烁：

float xAxis,yAxis, zAxis;
xAxis = self.manager.accelerometerData.acceleration.x;
yAxis = self.manager.accelerometerData.acceleration.y;
zAxis = self.manager.accelerometerData.acceleration.z;

// returns if the phone is lying on the table:
if (zAxis < -0.8 || zAxis > 0.8) return;

CGFloat angle =  atan2f(xAxis, yAxis ); // The angle!!!

float noise = 0.011; // Flicker noise (the noise you want to filter)

// max and min are global variables
if (angle > max){
    max = angle;
    min = max - noise;
}
if (angle < min){
    min = angle;
    max = min + noise;
}

// Average: (no flickering):
angle = min + (max - min) / 2.0;

CMMotionManager deviceMotion态度值过度“闪烁”

3 个答案: