Patent ID: 7957558

Claim:
A system for optically tracking a mobile device comprising: a light source configured to emit illumination light toward a navigation surface; an image sensor array positioned to receive the illumination light reflected from the navigation surface, the image sensor array being configured to generate frames of image data in response to the received illumination light; a navigation engine operably connected to the image sensor array to receive the frames of image data, the navigation engine being configured to correlate the frames of image data to produce a first displacement value along a first direction and a second displacement value along a second direction; and a tracking module operably connected to the navigation engine to receive the first and second displacement values to compute first and second tracking values that indicate the current position of the mobile device, the tracking module being configured to compute the first tracking value using the second displacement value and the sine of a tracking angle value and to compute the second tracking value using the second displacement value and the cosine of the tracking angle value, the tracking angle value being an angle value derived using at least one previous second displacement value.