System and method for determining the activity of a mobile element
First Claim
1. A method for determining activity of a user having a mobile element coupled thereto, the mobile element comprising at least one motion sensor comprising an accelerometer having at least two measurement axes, the method comprising:
- using the mobile element to measure movement of the user along the at least two axes to generate a corresponding signal S(n) by the motion sensor at discrete times from zero to N when the mobile element is in a state E(n) characterizing a posture of the user;
filtering the signal S(n) to obtain a first component y(n) of high-frequency portions of the signal S(n), said high frequency portions being above a first frequency threshold on each axis of the motion sensor, and a second component x(n) of low frequency portions of the signal S(n), said low frequency portions being below a second frequency threshold lower than the first frequency threshold on at least one axis of the motion sensor;
calculating by a processor a combination θ
(n) of a norm of the first component and a contribution of the second component;
determining by the processor a list of the most likely states E(ki) characterizing the postures of the user during a period between time zero and N from a calculation of;
a probability function of obtaining θ
(n) from the signal S(n) when the mobile element is in the E(n) state;
a probability function of a transition from the E(n−
1) state to the E(n) state; and
probability functions of each state of the mobile element at time zero; and
outputting a most likely activity of the user as a sequence of most likely postures.
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Accused Products
Abstract
A system for determining activity of a mobile element, includes at least one motion sensor having a measurement axis, and which is securely connected to the mobile element. A filter for selects, for each measurement axis of the motion sensor, high frequencies above a first threshold, and processing equipment for determines a unidimensional high-frequency component (y(n)) equal to the square of the Euclidean norm of the high frequencies along the measurement axes of the motion sensor. A calculator calculates, for each state, probability density functions (Py,i) of the high-frequency component, the probability density function corresponding to each state according to a Chi-square law with a degree of freedom equal to the number of measurement axes of the motion sensor. An analyzer defines states of the mobile element, utilizing the probability density function of the high-frequency component for each state, together with the probabilities of transitions between two successive states.
8 Citations
8 Claims
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1. A method for determining activity of a user having a mobile element coupled thereto, the mobile element comprising at least one motion sensor comprising an accelerometer having at least two measurement axes, the method comprising:
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using the mobile element to measure movement of the user along the at least two axes to generate a corresponding signal S(n) by the motion sensor at discrete times from zero to N when the mobile element is in a state E(n) characterizing a posture of the user; filtering the signal S(n) to obtain a first component y(n) of high-frequency portions of the signal S(n), said high frequency portions being above a first frequency threshold on each axis of the motion sensor, and a second component x(n) of low frequency portions of the signal S(n), said low frequency portions being below a second frequency threshold lower than the first frequency threshold on at least one axis of the motion sensor; calculating by a processor a combination θ
(n) of a norm of the first component and a contribution of the second component;determining by the processor a list of the most likely states E(ki) characterizing the postures of the user during a period between time zero and N from a calculation of; a probability function of obtaining θ
(n) from the signal S(n) when the mobile element is in the E(n) state;a probability function of a transition from the E(n−
1) state to the E(n) state; andprobability functions of each state of the mobile element at time zero; and outputting a most likely activity of the user as a sequence of most likely postures. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A system for determining activity of a user, the system including a mobile element capable of being coupled to the user, the mobile element comprising at least one motion sensor comprising an accelerometer having at least two measurement axes, said system further comprising:
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a module to measure movement of the user along the at least two axes to generate a corresponding signal S(n) by the motion sensor at discrete times from zero to N when the mobile element is in a state E(n) characterizing a posture of the user; a module for filtering the signal S(n) to obtain a first component y(n) of high-frequency portions of the signal S(n), said high frequency portions being above a first frequency threshold on each axis of the motion sensor, and a second component x(n) of low frequency portions of the signal S(n), said low frequency portions being below a second frequency threshold lower than the first frequency threshold on at least one axis of the motion sensor; a module for determining a combination θ
(n) of a norm of the first component and a contribution of the second component;a module for determining a list of the most likely states E(ki,) characterizing the postures of the user during a period between time zero and N from a calculation of; a probability function of obtaining θ
(n) from the signal S(n) when the mobile element is in the E(n) state;a probability function of a transition from the E(n−
1) state to the E(n) state; andprobability functions of each state of the mobile element at time zero; and an output module configured to output a most likely activity of the user as a sequence of most likely postures. - View Dependent Claims (8)
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Specification