Speckle-based two-dimensional motion tracking
First Claim
1. A motion tracking device, comprising:
- a laser positioned to direct a beam at a surface moving relative to the device;
an array of photosensitive pixels positioned to receive light from the beam after the light reflects from the surface; and
a processor configured to perform steps that include (a) calculating a series of data values representing a range of pixel intensities along a first dimension at a time t, (b) calculating a series of data values representing a range of pixel intensities along a second dimension at the time t, (c) calculating a series of data values representing a range of pixel intensities along the first dimension at a time t+Δ
t, (d) calculating a series of data values representing a range of pixel intensities along the second dimension at the time t+Δ
t, (e) determining motion along the first dimension using data from the series calculated in steps (a) and (c), and (f) determining motion along the second dimension using data from the series calculated in steps (b) and (d).
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Accused Products
Abstract
Reflected laser light having a speckle pattern is received in a pixel array. Pixel outputs are combined into series representing pixel intensities along particular dimensions at times t and t+Δt. Centroids for each series can be identified, and vectors determined for movement of centroids from time t to time t+Δt. Crossing points may alternatively be identified for data within each series relative to a reference value for that series, and vectors determined for movement of crossing points from time t to time t+Δt. A probability analysis may be used to extract a magnitude and direction of array displacement from a distribution of movement vectors. A series of data values corresponding to time t+Δt may alternatively be correlated to advanced and delayed versions of a series of data values corresponding to time t. The highest correlation is then used to determine movement.
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Citations
20 Claims
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1. A motion tracking device, comprising:
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a laser positioned to direct a beam at a surface moving relative to the device;
an array of photosensitive pixels positioned to receive light from the beam after the light reflects from the surface; and
a processor configured to perform steps that include (a) calculating a series of data values representing a range of pixel intensities along a first dimension at a time t, (b) calculating a series of data values representing a range of pixel intensities along a second dimension at the time t, (c) calculating a series of data values representing a range of pixel intensities along the first dimension at a time t+Δ
t,(d) calculating a series of data values representing a range of pixel intensities along the second dimension at the time t+Δ
t,(e) determining motion along the first dimension using data from the series calculated in steps (a) and (c), and (f) determining motion along the second dimension using data from the series calculated in steps (b) and (d). - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A motion tracking device, comprising:
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a laser positioned to direct a beam at a surface moving relative to the device;
an array of photosensitive pixels positioned to receive light from the beam after the light reflects from the surface, the array including a first arm including a first sub-array, the first sub-array having a size of m pixels in a direction generally parallel to a first dimension and n pixels in a direction generally perpendicular to the first dimension, where m and n is each greater than 1, a second arm including a second sub-array, the second sub-array having a size of M pixels in a direction generally parallel to a second dimension and N pixels in a direction generally perpendicular to the second dimension, where M and N is each greater than 1, and a pixel-free region between the first and second arms, the pixel-free region being larger than a square having sides equal to the average pixel pitch within the first and second arms; and
a processor configured to calculate movement in the first and second dimensions based on data generated from output of the pixels in the first and second sub-arrays. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18, 19, 20)
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Specification