Patent ID: 9538939
Date: 2017-01-10
CPC Classifications: A61B

Claim:
1. 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.