iphone加速度计的最大采样率

Question

有人知道iphone加速度计的最大采样率是多少吗？我想有一个高更新率。我将其设置为updateInterval为1.0/ 300.0，但是我似乎没有得到那么高的更新率。

所以有人能告诉我我们可以获得的最大更新率是多少，或者我如何才能获得更高的更新率。

Answer 1

iPhone 6的最大加速度计和陀螺仪采样率为100 The 。您可以自己对此进行经验测试。下面是代码。

/******************************************************************************/
// First create and initialize two NSMutableArrays. One for accel data and one
// for gyro data. Then create and initialize CMMotionManager.  Finally,
// call this function

- (void) TestRawSensors
{
   speedTest = 0.0001; // Lets try 10,000Hz
   motionManager.accelerometerUpdateInterval = speedTest;
   motionManager.gyroUpdateInterval = speedTest;


    [motionManager startAccelerometerUpdatesToQueue: [NSOperationQueue currentQueue]
    withHandler: ^(CMAccelerometerData  *accelerometerData, NSError *error)
    {
       [rawAccelSpeedTest addObject: [NSNumber numberWithDouble: accelerometerData.timestamp]];
       [rawAccelSpeedTest addObject: [NSNumber numberWithDouble: accelerometerData.acceleration.x]];

       if (error)
       {
          NSLog(@"%@", error);
       }

       if (rawAccelSpeedTest.count > 100)
       {
          [motionManager stopAccelerometerUpdates];

          for (uint16_t i = 0; i < rawAccelSpeedTest.count; i+=2)
          {
             NSLog(@"Time: %f   Accel: %f", [rawAccelSpeedTest[i] doubleValue],
                                            [rawAccelSpeedTest[i+1] doubleValue]);
          }
       }
    }];


   [motionManager startGyroUpdatesToQueue: [NSOperationQueue currentQueue]
                              withHandler: ^(CMGyroData *gyroData, NSError *error)
    {
       [rawGryoSpeedTest addObject: [NSNumber numberWithDouble: gyroData.timestamp]];
       [rawGryoSpeedTest addObject: [NSNumber numberWithDouble: gyroData.rotationRate.x]];

       if (error)
       {
          NSLog(@"%@", error);
       }

       if (rawGryoSpeedTest.count > 100)
       {
          [motionManager stopGyroUpdates];

          for (uint16_t i = 0; i < rawGryoSpeedTest.count; i+=2)
          {
             NSLog(@"Time: %f   Rate: %f", [rawGryoSpeedTest[i] doubleValue],
                                           [rawGryoSpeedTest[i+1] doubleValue]);
          }

       }
    }];
}

Answer 2

尽管文档上写着The maximum frequency at which you can request updates is hardware-dependent but is usually at least 100 Hz.，但在我看来，的最大采样率仍然是100 is 。

我的解决方法是使用名为MotionGraphs的CoreMotion现有示例代码，并将startUpdates函数调整为如下所示：

func startUpdates() {
    guard let motionManager = motionManager, motionManager.isGyroAvailable else { return }

    sampleCount = 0
    let methodStart = Date()

    motionManager.gyroUpdateInterval = TimeInterval(1.0/100000.0) // Hardcoded to something verfy fast
    motionManager.startGyroUpdates(to: .main) { gyroData, error in
        self.sampleCount += 1
        //...view update code removed
        if (self.sampleCount >= 100) {
            let methodFinish = Date()
            let executionTime = methodFinish.timeIntervalSince(methodStart)
            print("Duration of 100 Gyro samples: \(executionTime)")
            self.stopUpdates()
        }
    }
}

我还设置了motionManager.deviceMotionUpdateInterval = TimeInterval(1.0/100000.0)作为很好的度量(以防它是全局速率)。

有了加速计和陀螺仪的代码，我确认iOS 11.4上的iPhone 8仍然可以达到100 in左右的最大速度。

Duration of 100 Accelerometer samples: 0.993090987205505
Duration of 100 Accelerometer samples: 0.995925068855286
Duration of 100 Accelerometer samples: 0.993505954742432
Duration of 100 Accelerometer samples: 0.996459007263184
Duration of 100 Accelerometer samples: 0.996203064918518

Duration of 100 Gyro samples: 0.989820957183838
Duration of 100 Gyro samples: 0.985687971115112
Duration of 100 Gyro samples: 0.989449977874756
Duration of 100 Gyro samples: 0.988754034042358

Answer 3

也许是复制品。看

update frequency set for deviceMotionUpdateInterval it's the actual frequency?

Actual frequency of device motion updates lower than expected, but scales up with setting

如果使用旧的UIAccerometerDelegate接口，同样也是有效的。