UIAccelerometer距离计算

Question

我已经使用以下代码来计算距离，当设备从一个地方移动到another.Is它正确与否，请看我的代码。

-(void)accelerometer:(UIAccelerometer *)accelerometer didAccelerate:(UIAcceleration *)acceleration
{
    NSDate *now = [NSDate date];
    NSTimeInterval intervalDate = [now timeIntervalSinceDate:now_prev];

    sx = acceleration.x * kFilteringFactor + sx * (1.0 - kFilteringFactor);
    sy = acceleration.y * kFilteringFactor + sy * (1.0 - kFilteringFactor);
    sz = acceleration.z * kFilteringFactor + sz * (1.0 - kFilteringFactor);

    [xLabel setText:[NSString stringWithFormat:@"%.2f",sx]];
    [yLabel setText:[NSString stringWithFormat:@"%.2f",sy]];
    [zLabel setText:[NSString stringWithFormat:@"%.2f",sz]];

    float aValue = sqrtf(sx*sx+sy*sy+sz*sz);
    [gLabel setText:[NSString stringWithFormat:@"%.2f g",aValue]];

    velX += (sx * intervalDate);
    distX += (velX * intervalDate);

    velY += (sy * intervalDate);
    distY += (velY * intervalDate);

    velZ += (sz * intervalDate);
    distZ += (velZ * intervalDate);

    float distance = sqrtf(distX*distX+distY*distY+distZ*distZ);
    [distanceLabel setText:[NSString stringWithFormat:@"%.2f",distance*0.0006213f]];

    now_prev = [now retain];

}

Answer 1

为什么试图从加速器数据中获取距离将是非常低效的，原因有很多。为了跟踪您的初始位置，您需要将所有加速度值连续集成到一个向量中，并且最好是以非常高的采样率(计算中的大间隙将导致不准确)。

这个方法本身并不是很难理解(或者谷歌)；This question explains how to do the maths and pseudocode for such an integration approach