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Determining motion states

  • US 8,892,390 B2
  • Filed: 06/03/2011
  • Issued: 11/18/2014
  • Est. Priority Date: 06/03/2011
  • Status: Active Grant
First Claim
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1. A method performed by a mobile device, the method comprising:

  • receiving accelerometer data from accelerometer sensors onboard the mobile device, wherein the accelerometer data comprises tri-axial accelerometer samples and represents acceleration of the mobile device in three-dimensional space;

    determining, by one or more processors of the mobile device, an accelerometer signal vector representing at least a force due to gravity on the mobile device;

    calculating, by the one or more processors of the mobile device, two-dimensional accelerometer data orthogonal to the accelerometer signal vector, including;

    computing a roll angle and a pitch angle required to rotate the accelerometer signal vector to substantially align with a vertical axis of the accelerometer samples; and

    rotating vectors representing each of the accelerometer samples by the computed roll and pitch angles such that the accelerometer signal vector is substantially aligned with the vertical axis and an orthogonal plane that is orthogonal to the accelerometer signal vector is orthogonal to the vertical axis; and

    determining, by the one or more processors of the mobile device, a motion state of the mobile device based on the two-dimensional accelerometer data, wherein determining the motion state includes determining at least one of whether the mobile device has a vertical movement motion state or whether the mobile device has a horizontal movement motion state.

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