Windows Phone加速度计抖动

Question

I would like to get accelerometer readings every 10ms from my Windows Phone 8, but instead I observe some jitter: the spacing between readings will be 8,10,12,9, or the like. So approximately 10, but not exactly.

I was wondering whether someone could suggest a way to get more reliable readings.

The core of my code looks like this:

var accelerometer = Windows.Devices.Sensors.Accelerometer.GetDefault();
accelerometer.ReadingChanged += accelerometer_ReadingChanged;
accelerometer.ReportInterval = 10;

The phone reports a MiminumReportingInterval of 10, so that should be fine. My callback just adds the numbers to a list, which I will send over the network at the end.

I am looking at the time in AccelerometerReadingChangedEventArgs.Timestamp, and that's where I see that the interval isn't always 10ms. Here's what the times looked like in the latest measurements: 105,118,128,134,146,157,163,177,187,198,208,213,232,238,245,255,263,279,285,295,303,313,324,334,345,355,363,375,385

So: is there something I can do to get more precisely spaced measurements? Or is this just the best this particular hardware can do?

Answer 1

There is a great article on Windows Phone Developer Blog which covers accelerometer in details.

One of the points of the article is that, yes, the stream of values can and most probably will be 'jittery' so you should implement some method of filtering. One such method is a low pass filter.

The smoother the data after filtering, the bigger the delay will be between the actual change and the reading. In other words, if you used accelerometer in a game as a 'steering wheel', a lot of filtering will result in late turning of a car, but no filtering will probably result in a jittery car. So, the best is to set it somewhere in between, depending on the use case.