iphone - iphone中加速度计的最大采样率

Question

有谁知道iphone加速度计的最大采样率是多少。我想要有高更新率。我将它设置为 updateInterval 为 1.0/ 300.0 但似乎我没有得到那么高的更新率。

那么任何人都可以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高更新率。

Answer 1

iPhone 6 上的最大加速度计和陀螺仪采样率为100Hz。您可以自己进行经验测试。这是代码。

/******************************************************************************/
// 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

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

我的解决方法是采用 CoreMotion 的现有示例代码 MotionGraphs 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motionManager.deviceMotionUpdateInterval = TimeInterval(1.0/100000.0)了良好的衡量标准（以防万一是全球汇率）。

有了加速度计和陀螺仪的代码，我确认 iOS 11.4 上的 iPhone 8 的最大频率仍然在 100Hz 左右。

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

也许重复。看着

为 deviceMotionUpdateInterval 设置的更新频率是实际频率吗？

设备运动更新的实际频率低于预期，但随着设置的增加而增加

如果使用旧的 UIAccerometerDelegate 接口，同样应该有效。