如何从加速计计算正确的速度值

我需要计算空间的iPhone速度，例如打孔速度。
我的第一个问题是：是否加速度值accelerometer:didAccelerate与此筛选操作： 

 gravity_x = acceleration.x * kFilteringFactor + gravity_x * (1.0 - kFilteringFactor); gravity_y = acceleration.y * kFilteringFactor + gravity_y * (1.0 - kFilteringFactor); gravity_z = acceleration.z * kFilteringFactor + gravity_z * (1.0 - kFilteringFactor); float gravityNorm = sqrt(gravity_x * gravity_x + gravity_y * gravity_y + gravity_z * gravity_z); accelX = acceleration.x - gravity_x / gravityNorm; accelY = acceleration.y - gravity_y / gravityNorm; accelZ = acceleration.z - gravity_z / gravityNorm;

与使用CoreMotion相同
motionManager.deviceMotion.userAcceleration.x; motionManager.deviceMotion.userAcceleration.y; motionManager.deviceMotion.userAcceleration.z; ？

接下来，根据同样的问题，我做了以下 

  const float accuracy=10; float accx = (float) ((int) (accelX * accuracy))/ accuracy; float accy= (float) ((int) (accelY * accuracy))/ accuracy; float accz= (float) ((int) (accelZ * accuracy))/ accuracy;

为了四舍五入的价值，那么，我认为，我获得当前的速度 

 float dx = accx*9.81+prevX*9.81; float dy = accy*9.81+prevY*9.81; float dz = accz*9.81+prevZ*9.81; speed_after_x = dx/2*myAccelerometer.updateInterval+speed_before_x; speed_after_y = dy/2*myAccelerometer.updateInterval+speed_before_y; speed_after_z = dz/2*myAccelerometer.updateInterval+speed_before_z;

根据iphone的加速度计速度和距离
然后 

  prevX=accx; prevY=accy; prevZ=accz; speed_before_x=speed_after_x; speed_before_y=speed_after_y; speed_before_z=speed_after_z;

最后以vector的长度来计算速度 

  float speed = sqrt(speed_after_x*speed_after_x+speed_after_y*speed_after_y+speed_after_z*speed_after_z); if (max_speed<speed) max_speed = speed;

但是，标签中包含的速度值总是在增加。 我的意思是如果我移动设备，然后停止，速度值不会变成0.不加速度补偿自己在0？

这是我设法散列的示例代码。 我现在就把它放在这里： 

 // // ViewController.m // Acce // // Created by Diziet on 14/05/2012. // Copyright (c) 2012 __MyCompanyName__. All rights reserved. // #import "ViewController.h" @interface ViewController () { UIAccelerationValue gravX; UIAccelerationValue gravY; UIAccelerationValue gravZ; UIAccelerationValue prevVelocity; UIAccelerationValue prevAcce; } @property (strong) UIAccelerometer *sharedAcc; @end @implementation ViewController @synthesize sharedAcc = _sharedAcc; #define kAccelerometerFrequency 50.0 //Hz #define kFilteringFactor 0.1 - (void)viewDidLoad { [super viewDidLoad]; // Do any additional setup after loading the view, typically from a nib. self.sharedAcc = [UIAccelerometer sharedAccelerometer]; self.sharedAcc.delegate = self; self.sharedAcc.updateInterval = 1 / kAccelerometerFrequency; gravX = gravY = gravZ = prevVelocity = prevAcce = 0.f; } - (void)viewDidUnload { [super viewDidUnload]; // Release any retained subviews of the main view. } - (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation { return (interfaceOrientation != UIInterfaceOrientationPortraitUpsideDown); } - (UIAccelerationValue)tendToZero:(UIAccelerationValue)value { if (value < 0) { return ceil(value); } else { return floor(value); } } #define kAccelerometerFrequency 50.0 //Hz #define kFilteringFactor 0.1 - (void)accelerometer:(UIAccelerometer *)accelerometer didAccelerate:(UIAcceleration *)acceleration { gravX = (acceleration.x * kFilteringFactor) + (gravX * (1.0 - kFilteringFactor)); gravY = (acceleration.y * kFilteringFactor) + (gravY * (1.0 - kFilteringFactor)); gravZ = (acceleration.z * kFilteringFactor) + (gravZ * (1.0 - kFilteringFactor)); UIAccelerationValue accelX = acceleration.x - ( (acceleration.x * kFilteringFactor) + (gravX * (1.0 - kFilteringFactor)) ); UIAccelerationValue accelY = acceleration.y - ( (acceleration.y * kFilteringFactor) + (gravY * (1.0 - kFilteringFactor)) ); UIAccelerationValue accelZ = acceleration.z - ( (acceleration.z * kFilteringFactor) + (gravZ * (1.0 - kFilteringFactor)) ); accelX *= 9.81f; accelY *= 9.81f; accelZ *= 9.81f; accelX = [self tendToZero:accelX]; accelY = [self tendToZero:accelY]; accelZ = [self tendToZero:accelZ]; UIAccelerationValue vector = sqrt(pow(accelX,2)+pow(accelY,2)+pow(accelZ, 2)); UIAccelerationValue acce = vector - prevVelocity; UIAccelerationValue velocity = (((acce - prevAcce)/2) * (1/kAccelerometerFrequency)) + prevVelocity; NSLog(@"X %g Y %g Z %g, Vector %g, Velocity %g",accelX,accelY,accelZ,vector,velocity); prevAcce = acce; prevVelocity = velocity; } @end

这将需要修改您的需求，特别是因为我只是把价值之后扔掉。 logging为“速度”的结果值“速度”在加速事件停止后趋向于极小的负值，例如* 10 ^ -17。 所以是的，在我的书中几乎是零。 你会想在那里做一些四舍五入的工作，甚至可能会把价值提高。 我不认为我可以得到0.2或0.3以上的高分，但是我又不想把手机扔到房间里（还没有）。

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