Android：使用加速度计计算的速度不正确

Question

我希望这不是重复的，因为我在 android 中看到了一些关于加速度计的相关帖子，但其中 none 对我有帮助。

我需要获取移动设备的 X 轴速度（仅）。

问题是当我沿直线移动我的设备时（初始速度 = 0），先加速然后减速（直到完全停止）我得到的计算速度与实际速度不匹配。

问题的主要症状是设备停止后，我计算的速度不为0。

我可以在结果中看到加速度和减速度（先是正加速度值，然后是负加速度值），但我认为它们不够准确。

无论我向哪个方向移动设备 (left/right)，都会发生这种情况。

我想我所要求的是一种可能以更智能的方式进行计算的方法，从而可以提高结果的准确性..

这是我的 onSensorChanged 代码：

public void onSensorChanged(SensorEvent sensorEvent) {
    if((!isCancelled()) && (this.isConnected)) {
        if(mode.equals("ac")) {

            // Getting X acceleration
            currentAccelX = sensorEvent.values[0];

            // Getting current sample timestamp
            currentTimeStamp = sensorEvent.timestamp;

            // if first sample then interval = 0
            if(prevTimeStamp == 0) prevTimeStamp = currentTimeStamp;

            // calculating interval (in seconds)
            interval = (currentTimeStamp - prevTimeStamp) * NS2S;

            // updating prevTimeStamp for next sample..
            prevTimeStamp = currentTimeStamp;

            // My device shows acceleration of about 0.22 when isn't moving at all
            // so for ignoring this offset:
            if(Math.abs(currentAccelX) < 0.3) currentAccelX = 0;


            // Updating the X-axis velocity
            currentVelocityX += currentAccelX * interval;

            Log.d(TAG, "ACCEL X IS: " + currentAccelX + " INTERVAL IS: " + interval + " VELOCITY X IS: " + currentVelocityX); }}}

以下是结果（来自日志）：

ACCEL X IS: 0.0 INTERVAL IS: 0.008392334 VELOCITY X IS: -0.17563461
ACCEL X IS: 0.5072479 INTERVAL IS: 0.008392334 VELOCITY X IS: -0.17137761
ACCEL X IS: 1.8605042 INTERVAL IS: 0.008392334 VELOCITY X IS: -0.15576364
ACCEL X IS: 2.970047 INTERVAL IS: 0.008392334 VELOCITY X IS: -0.130838
ACCEL X IS: 3.1661987 INTERVAL IS: 0.008392334 VELOCITY X IS: -0.10426621
ACCEL X IS: 2.5031128 INTERVAL IS: 0.008392334 VELOCITY X IS: -0.083259255
ACCEL X IS: 1.4252472 INTERVAL IS: 0.008392334 VELOCITY X IS: -0.07129811
ACCEL X IS: 0.66192627 INTERVAL IS: 0.008392334 VELOCITY X IS: -0.065743
ACCEL X IS: 0.8834839 INTERVAL IS: 0.008392334 VELOCITY X IS: -0.05832851
ACCEL X IS: 1.476593 INTERVAL IS: 0.008392334 VELOCITY X IS: -0.045936447
ACCEL X IS: 2.1182098 INTERVAL IS: 0.008392334 VELOCITY X IS: -0.028159723
ACCEL X IS: 2.5206451 INTERVAL IS: 0.008392334 VELOCITY X IS: -0.0070056263
ACCEL X IS: 2.5039368 INTERVAL IS: 0.008392334 VELOCITY X IS: 0.014008248
ACCEL X IS: 2.0747833 INTERVAL IS: 0.008392334 VELOCITY X IS: 0.03142052
ACCEL X IS: 1.6359253 INTERVAL IS: 0.008392334 VELOCITY X IS: 0.04514975
ACCEL X IS: 1.9437103 INTERVAL IS: 0.008392334 VELOCITY X IS: 0.061462015
ACCEL X IS: 2.5153046 INTERVAL IS: 0.008392334 VELOCITY X IS: 0.08257129
ACCEL X IS: 2.7262726 INTERVAL IS: 0.008392334 VELOCITY X IS: 0.10545108
ACCEL X IS: 2.6504364 INTERVAL IS: 0.008392334 VELOCITY X IS: 0.12769443
ACCEL X IS: 2.7267609 INTERVAL IS: 0.008392334 VELOCITY X IS: 0.15057832
ACCEL X IS: 3.2504425 INTERVAL IS: 0.008392334 VELOCITY X IS: 0.17785712
ACCEL X IS: 2.66333 INTERVAL IS: 0.008392334 VELOCITY X IS: 0.20020866
ACCEL X IS: 1.2032013 INTERVAL IS: 0.008392334 VELOCITY X IS: 0.21030633
ACCEL X IS: 0.0 INTERVAL IS: 0.008392334 VELOCITY X IS: 0.21030633
ACCEL X IS: -0.82492065 INTERVAL IS: 0.008392334 VELOCITY X IS: 0.20338333
ACCEL X IS: -1.1881866 INTERVAL IS: 0.008392334 VELOCITY X IS: 0.19341166
ACCEL X IS: -1.234375 INTERVAL IS: 0.008392334 VELOCITY X IS: 0.18305238
ACCEL X IS: -1.1171875 INTERVAL IS: 0.008392334 VELOCITY X IS: 0.17367657
ACCEL X IS: -0.66615295 INTERVAL IS: 0.008392334 VELOCITY X IS: 0.16808599
ACCEL X IS: 0.6031494 INTERVAL IS: 0.008392334 VELOCITY X IS: 0.17314783
ACCEL X IS: 1.6951294 INTERVAL IS: 0.008392334 VELOCITY X IS: 0.18737392
ACCEL X IS: 2.1244202 INTERVAL IS: 0.008392334 VELOCITY X IS: 0.20520276
ACCEL X IS: 2.0012054 INTERVAL IS: 0.008392334 VELOCITY X IS: 0.22199754
ACCEL X IS: 1.7078094 INTERVAL IS: 0.008392334 VELOCITY X IS: 0.23633005
ACCEL X IS: 1.6888428 INTERVAL IS: 0.008392334 VELOCITY X IS: 0.2505034
ACCEL X IS: 1.7953186 INTERVAL IS: 0.008392334 VELOCITY X IS: 0.2655703
ACCEL X IS: 2.3388367 INTERVAL IS: 0.008392334 VELOCITY X IS: 0.2851986
ACCEL X IS: 3.2739716 INTERVAL IS: 0.008392334 VELOCITY X IS: 0.31267485
ACCEL X IS: 4.067398 INTERVAL IS: 0.008392334 VELOCITY X IS: 0.3468098
ACCEL X IS: 4.221344 INTERVAL IS: 0.008392334 VELOCITY X IS: 0.38223672
 ACCEL X IS: 4.281769 INTERVAL IS: 0.008392334 VELOCITY X IS: 0.41817075
ACCEL X IS: 3.0664673 INTERVAL IS: 0.008392334 VELOCITY X IS: 0.44390556
ACCEL X IS: 1.0762634 INTERVAL IS: 0.008392333 VELOCITY X IS: 0.45293793
ACCEL X IS: -0.5091095 INTERVAL IS: 0.008392334 VELOCITY X IS: 0.44866532
ACCEL X IS: -0.82073975 INTERVAL IS: 0.008392334 VELOCITY X IS: 0.4417774
ACCEL X IS: 0.5644531 INTERVAL IS: 0.008392334 VELOCITY X IS: 0.4465145
ACCEL X IS: 3.284546 INTERVAL IS: 0.008392334 VELOCITY X IS: 0.4740795
ACCEL X IS: 4.3601074 INTERVAL IS: 0.008392334 VELOCITY X IS: 0.51067096
ACCEL X IS: 4.3199615 INTERVAL IS: 0.008392334 VELOCITY X IS: 0.54692554
ACCEL X IS: 3.0349426 INTERVAL IS: 0.008392334 VELOCITY X IS: 0.5723958
ACCEL X IS: 1.763977 INTERVAL IS: 0.008392334 VELOCITY X IS: 0.5871997
ACCEL X IS: 1.4712982 INTERVAL IS: 0.008392334 VELOCITY X IS: 0.5995473
ACCEL X IS: 2.1172028 INTERVAL IS: 0.008392334 VELOCITY X IS: 0.6173156
ACCEL X IS: 2.1423798 INTERVAL IS: 0.008392334 VELOCITY X IS: 0.63529515
ACCEL X IS: 1.6801605 INTERVAL IS: 0.008392334 VELOCITY X IS: 0.64939564
ACCEL X IS: 1.8257599 INTERVAL IS: 0.008392334 VELOCITY X IS: 0.66471803
ACCEL X IS: 1.8712311 INTERVAL IS: 0.008392334 VELOCITY X IS: 0.680422
ACCEL X IS: 2.1062775 INTERVAL IS: 0.008392334 VELOCITY X IS: 0.6980986
ACCEL X IS: 2.054016 INTERVAL IS: 0.008392334 VELOCITY X IS: 0.71533656
ACCEL X IS: 0.0 INTERVAL IS: 0.008392334 VELOCITY X IS: 0.71533656
ACCEL X IS: -2.2228088 INTERVAL IS: 0.008392334 VELOCITY X IS: 0.696682
ACCEL X IS: -2.936676 INTERVAL IS: 0.008392334 VELOCITY X IS: 0.6720364
ACCEL X IS: -3.1568298 INTERVAL IS: 0.008392334 VELOCITY X IS: 0.6455432
ACCEL X IS: -2.484604 INTERVAL IS: 0.008392334 VELOCITY X IS: 0.6246916
ACCEL X IS: -2.213089 INTERVAL IS: 0.008392334 VELOCITY X IS: 0.6061186
ACCEL X IS: -1.923996 INTERVAL IS: 0.008392334 VELOCITY X IS: 0.5899718
ACCEL X IS: -2.902832 INTERVAL IS: 0.008392334 VELOCITY X IS: 0.56561023
ACCEL X IS: -5.460327 INTERVAL IS: 0.008392334 VELOCITY X IS: 0.51978534
ACCEL X IS: -7.1407623 INTERVAL IS: 0.008392334 VELOCITY X IS: 0.45985767
ACCEL X IS: -8.03479 INTERVAL IS: 0.008392334 VELOCITY X IS: 0.39242703
ACCEL X IS: -8.921448 INTERVAL IS: 0.008392334 VELOCITY X IS: 0.31755525
ACCEL X IS: -10.293076 INTERVAL IS: 0.008392334 VELOCITY X IS: 0.23117232
ACCEL X IS: -11.660858 INTERVAL IS: 0.008392334 VELOCITY X IS: 0.1333105
ACCEL X IS: -12.821564 INTERVAL IS: 0.008392334 VELOCITY X IS: 0.025707655
ACCEL X IS: -12.108749 INTERVAL IS: 0.008392334 VELOCITY X IS: -0.07591301
ACCEL X IS: -9.302032 INTERVAL IS: 0.008392334 VELOCITY X IS: -0.15397877
ACCEL X IS: -5.889694 INTERVAL IS: 0.008392334 VELOCITY X IS: -0.20340705
ACCEL X IS: -3.0645447 INTERVAL IS: 0.008392334 VELOCITY X IS: -0.22912574
ACCEL X IS: -1.2965088 INTERVAL IS: 0.008392334 VELOCITY X IS: -0.24000648
ACCEL X IS: -0.36557007 INTERVAL IS: 0.008392334 VELOCITY X IS: -0.24307446
ACCEL X IS: 0.0 INTERVAL IS: 0.008392334 VELOCITY X IS: -0.24307446

*请注意，日志中的初始速度不是 0（而是 -0.17563461），因为当 phone 没有移动时，一些传感器错误会导致 "fake" 加速度值。

非常感谢。

Answer 1

我认为你应该使用Android提供的线性加速度传感器 API :

https://developer.android.com/reference/android/hardware/Sensor.html#TYPE_LINEAR_ACCELERATION

它似乎完全符合您的需求

编辑：要处理精度问题，您可以尝试执行手动校准（phone 必须平放在 table 上并且测量必须是 stable）以删除偏移量。在这里查看更多详细信息（尤其是结尾）：https://electronics.stackexchange.com/a/33387

但您还应该记住，传感器并不完美，尤其是在 phone 中，这就是为什么某些 phone 的传感器可能无法获得您想要的精度。解决方案是使您的算法处理适应传感器提供的精度，要么执行传感器融合（例如使用陀螺仪）。

Android：使用加速度计计算的速度不正确

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