System for analyzing a user's strides
AssigneeMovea
InventorsCyrille Soubeyrat, Anne Frassati
Life of this patent
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Abstract
A system for analyzing a user's strides has a first sensor assembly (EC1) furnished within a housing, with a triaxial magnetometer (3M) fixed to the housing (BT), which is associated with a moving frame (LF). First fixing means (MF1) fixes the first sensor assembly (EC1) to a leg segment of the user. Processing means (MT) calculates the angle of yaw (YawGF) and/or of pitch (PitchGF) and/or of roll (RollGF) of the first sensor assembly (EC1), and calculates the corresponding angular temporal variation or variations ( ⅆ Yaw GF ⅆ t , ⅆ Pitch GF ⅆ t , ⅆ Roll GF ⅆ t ) , in a fixed global frame (GF) relative to the terrestrial frame, on the basis of the measurements of the triaxial magnetometer (3M) delivered in the moving frame (LF).
Claims12
A system for analyzing a user's strides, comprising:
- a first sensor assembly having a housing, a triaxial magnetometer coupled to said housing, a triaxial accelerometer coupled to said housing, and having an associated moving frame;
- first fixing means adapted for coupling the first sensor assembly to a limb segment of a user;
- and
- a processor configured to calculate at least an angle of pitch of said first sensor assembly, and to calculate a corresponding angular temporal variation, in a fixed global frame associated with a terrestrial frame, utilizing measurements of said triaxial magnetometer delivered in said moving frame;
- wherein the processor is further configured to:
- determine an instant of start of a stride and an instant of end of said stride and phases of said stride, utilizing said temporal variation of the angle of pitch of the first sensor assembly;
- calculate values of parameters representative of a phase of said stride or of the complete stride, in three dimensions in the fixed global frame, by calculating a stride frame associated with the first sensor assembly, for the complete stride or for each phase of the stride, utilizing vectors obtained from said triaxial magnetometer at successive instants in the moving frame associated with the first sensor assembly, the stride frame being a principal plane of the complete stride or for each phase of the stride, the principal plane being determined by the processor as orthogonal to an axis calculated as a spatial axis onto which projections of the vectors obtained from said triaxial magnetometer at successive instants vary the least;
- and
- calculate orthogonal projections of measurement vectors obtained from the triaxial accelerometer and from the triaxial magnetometer on axes of the stride frame;
- wherein the fixed global frame associated with the terrestrial frame is the orthogonal projection on the stride frame of the measurement vectors obtained from the triaxial magnetometer.
A method for analyzing a user's strides, in which:
- a temporary variation of an angle of pitch of a first sensor assembly, comprising a triaxial magnetometer coupled to a limb segment of the user and a triaxial accelerometer coupled to said limb segment, is calculated utilizing measurements of said first sensor assembly;
- wherein:
- an instant of start of a stride and an instant of end of said stride and phases of said stride are determined by calculating a temporal variation of the angle of pitch of the first sensor assembly;
- and
- values of parameters representative of a phase of said stride or of a complete stride, in three dimensions, are calculated in a fixed global frame associated with a terrestrial frame, by calculating a stride frame associated with the first sensor assembly based on vectors obtained from said triaxial magnetometer at successive instants, in a moving frame associated with the first sensor assembly, in which the stride frame is a principal plane of the complete stride or for each phase of the stride, the principal plane being determined as orthogonal to an axis calculated as a spatial axis onto which projections of the vectors obtained from said triaxial magnetometer at successive instants vary the least;
- and
- orthogonal projections of measurement vectors obtained from the triaxial accelerometer and from the triaxial magnetometer on axes of the stride frame associated with the first sensor assembly for the stride or per phase of the stride are calculated;
- wherein the fixed global frame associated with the terrestrial frame is said orthogonal projection of the measurement vectors obtained from the triaxial magnetometer in the stride frame.
Dependencies are inferred from the claim text.