Device for monitoring a user and a method for calibrating the device
First Claim
1. A method of calibrating a device that is to be attached to a user and used to monitor the user, the method comprising:
- (i) prior to attachment of the device to the user, aligning the device with respect to the user to substantially align a measurement reference frame of the device with a reference frame of the user and obtaining a first measurement of an orientation of the device with respect to a world reference frame using the device;
(ii) estimating a posture of the user;
(iii) after attachment of the device to the user, obtaining a second measurement of the orientation of the device with respect to the world reference frame using the device; and
(iv) with at least one electronic processor, determining a transformation matrix for use in transforming subsequent measurements obtained by the device into the reference frame of the user, the transformation matrix being calculated using the obtained first and second measurements, the estimated posture of the user, and information on an amount of rotation of the device relative to the user about a vertical axis in the world reference frame between (i) and (ii).
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Accused Products
Abstract
A method of calibrating a monitoring device to be attached to a user is provided. Prior to attachment of the device, the device is aligned with respect to the user such that the measurement reference frame of the device is substantially aligned with a reference frame of the user. A first measurement of the orientation of the device with respect to a world reference frame is obtained. After attachment of the device, a second measurement of the orientation of the device with respect to a world reference frame is obtained. A transformation matrix is determined for use in transforming subsequent measurements obtained by the device into the reference frame of the user. The matrix is calculated using the first and second measurements and information on the amount of rotation of the device relative to the user about a vertical axis in the world reference frame between the first and second measurements being taken.
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Citations
18 Claims
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1. A method of calibrating a device that is to be attached to a user and used to monitor the user, the method comprising:
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(i) prior to attachment of the device to the user, aligning the device with respect to the user to substantially align a measurement reference frame of the device with a reference frame of the user and obtaining a first measurement of an orientation of the device with respect to a world reference frame using the device; (ii) estimating a posture of the user; (iii) after attachment of the device to the user, obtaining a second measurement of the orientation of the device with respect to the world reference frame using the device; and (iv) with at least one electronic processor, determining a transformation matrix for use in transforming subsequent measurements obtained by the device into the reference frame of the user, the transformation matrix being calculated using the obtained first and second measurements, the estimated posture of the user, and information on an amount of rotation of the device relative to the user about a vertical axis in the world reference frame between (i) and (ii). - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A non-transitory computer readable medium comprising a plurality of program code portions for carrying out a method executed by a suitable computer or processor, the method comprising:
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prior to attachment of a device to a user, obtaining a first acceleration measurement as an indication of the orientation of the reference frame of the user with respect to a world reference frame prior to attachment of the device to the user; following attachment of the device to the user, obtaining a second acceleration measurement as a measurement of the orientation of the device with respect to a world reference frame; and with at least one electronic processor, calculating a transformation matrix for use in transforming subsequent acceleration measurements obtained by the device into the reference frame of the user, the transformation matrix being calculated using the obtained first and second measurements and information on the amount of rotation of the device relative to the user about a vertical axis of the world reference frame between the first and second measurements being taken;
wherein calculating the transformation matrix comprises;with the at least one electronic processor, computing a first coordinate vector d that is orthonormal to a first measurement b; with the at least one electronic processor, computing a second coordinate vector f that is orthonormal to b and d; with the at least one electronic processor, computing support vectors si and radii ri of the circles C1, C2 and C3 on which tips of the α
basis vectors lie for iε
{1, 2, 3};if |ak|=1 for some k then, with the at least one electronic processor, computing tk=sign (ak)b; with the at least one electronic processor, computing the p-th column of the transformation matrix; and with the at least one electronic processor, computing one or more remaining resolvable angles and a corresponding one or more columns of transformation matrix. - View Dependent Claims (12)
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13. A device for monitoring a user, the device being suitable for attachment to a user, the device comprising:
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a sensor configured to measure accelerations; and at least one electronic processor programmed to process the acceleration measurements by operations including, when the device is operating in a calibration mode; using a first acceleration measurement as an indication of an orientation of a reference frame of the user with respect to a world reference frame obtained prior to attachment of the device to the user and a second acceleration measurement as a measurement of the orientation of the device with respect to the world reference frame following attachment of the device to the user, calculating a transformation matrix for use in transforming subsequent acceleration measurements obtained by the device into the reference frame of the user, the transformation matrix being calculated using the obtained first and second measurements and information on the amount of rotation of the device relative to the user about a vertical axis of the world reference frame between the first and second measurements being taken; and further calculating the transformation matrix with an estimated posture of the user. - View Dependent Claims (14, 15, 16, 17, 18)
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Specification