Hybrid sensing techniques for position determination
First Claim
1. A method of determining the time-varying absolute position of a device with respect to a surface having a position-encoded portion and an obscured portion, wherein the position-encoded portion bears accessible encoded position data and the obscured portion does not bear accessible position data, the method comprising the steps of:
- moving the device with respect to the surface;
measuring a time-varying vector representing the relative movement of the device over the position-encoded portion and the obscured portion of said surface during motion of the device;
measuring at least one absolute position of the device with respect to the position-encoded portion of said surface during a portion of said motion when said position-encoded portion of said surface is accessible;
initializing the position of the vector to the at least one absolute position measurement thereby measuring the absolute position of the vector and thus the time-varying absolute position of the device; and
recording the measured time-varying absolute position of the device for subsequent outputting to an interpreter mechanism.
1 Assignment
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Accused Products
Abstract
The invention provides for a method and apparatus for improving error-correction in non-contact optical position sensing. The primary application is in page-based data input contexts such as form-filling and paper-based web interfaces and GUIs. The invention utilises a combined measurement of the relative movement of a device in relation to a fixed surface and at least one measurement of the absolute position of the device. Absolute measurement of position is preferably carried out using a position-encoded glyph bed embedded on the fixed surface. Based on the at least single absolute measurement, the relative measurement of the devices movement, or stroke, is normalised to the properly measure absolute position and thus substantial interruptions in the detection of the absolute stroke position can be tolerated and corrected for.
16 Citations
24 Claims
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1. A method of determining the time-varying absolute position of a device with respect to a surface having a position-encoded portion and an obscured portion, wherein the position-encoded portion bears accessible encoded position data and the obscured portion does not bear accessible position data, the method comprising the steps of:
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moving the device with respect to the surface; measuring a time-varying vector representing the relative movement of the device over the position-encoded portion and the obscured portion of said surface during motion of the device; measuring at least one absolute position of the device with respect to the position-encoded portion of said surface during a portion of said motion when said position-encoded portion of said surface is accessible; initializing the position of the vector to the at least one absolute position measurement thereby measuring the absolute position of the vector and thus the time-varying absolute position of the device; and recording the measured time-varying absolute position of the device for subsequent outputting to an interpreter mechanism. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A method of determining the absolute position of a stroke made by a measurement device with respect to a surface, said surface having embedded thereon position encoding indicia, the method comprising:
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moving the measurement device over the position-encoded surface, and whenever the measurement device passes over said one or more position encoding indicia, at any point of said motion, detecting one or more position encoding indicia, thereby calculating at least one absolute position measurement of the device; in conjunction with the aforementioned detection, measuring the relative movement of the device with respect to the position-encoded surface and thereby calculating a time-varying motion vector representing the movement of the device with respect to the surface; calculating the absolute location of the stroke with respect to the position-encoded surface on the basis of at least one measurement of the absolute position in combination with the time-varying motion vector; and recording the calculated time-varying absolute position of the device for subsequent outputting to an interpreter mechanism. - View Dependent Claims (12, 13, 14, 15, 16)
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17. A measurement device for determining the time-varying absolute position of the device with respect to a surface having a position-encoded portion with accessible encoded position data and an obscured portion where encoded position data is not accessible, said device including:
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a first measuring device arranged to determine at least one absolute position of the device with respect to the position-encoded portion of said surface; a second measuring device arranged to determine a time-varying vector representing the relative movement of the device with respect to the surface, wherein the first measuring device is further arranged to determine said at least one absolute position of the device at any time while said second measuring device is determining said time-varying vector; processing means adapted to initialize the position of the vector to the at least one absolute position measurement so as to produce a signal representing the absolute position of the vector and thus the time-varying absolute position of the device; and recording means for recording the absolute position signal for subsequent outputting to an interpreter mechanism. - View Dependent Claims (18, 19, 20, 21, 22, 23)
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24. A measurement device for determining the absolute position of a stroke made by the measurement device with respect to a surface, said surface having embedded thereon position encoding indicia, the measurement device including:
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a first measuring device arranged to detect one or more position encoding indicia and determine at least one absolute position measurement of the device; a second measuring device arranged to measure the relative movement of the device with respect to the surface and output a time-varying motion vector representing the movement of the device with respect to the surface, wherein the first measuring device is provided for determining said at least one absolute position of the device whenever the first measuring device passes by said one or more position encoding indicia during the relative movement of the measurement device; processing means adapted to calculate the absolute location of the stroke with respect to the surface on the basis of the at least one measurement of the absolute position in combination with the measurement of the time-varying motion vector; and recording means for recording the calculated absolute position of the stroke for subsequent outputting to an interpreter mechanism.
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Specification