초록 ▼

Devices and methods for determining various occurrences and anomalies within a step are provided. A device to determine characteristics of a step includes at least one sensor to measure acceleration of a foot in at least two directions, at least one processor to execute instructions stored in a memo

Devices and methods for determining various occurrences and anomalies within a step are provided. A device to determine characteristics of a step includes at least one sensor to measure acceleration of a foot in at least two directions, at least one processor to execute instructions stored in a memory and to determine accelerations in first and/or second directions meet criteria to determine a footstrike and a push off of a foot from a surface. Slipping of feet while walking and running, clipping of feet while walking and running, and tripping and falling while walking and running may be indicators of overall health and fitness, particularly in older individuals.

대표청구항 ▼

1. A device to determine characteristics of a step, the device comprising: at least one sensor to measure acceleration of a foot in at least two directions;at least one processor to execute instructions stored in a memory and to control acceleration data measured by the at least one sensor to be sto

1. A device to determine characteristics of a step, the device comprising: at least one sensor to measure acceleration of a foot in at least two directions;at least one processor to execute instructions stored in a memory and to control acceleration data measured by the at least one sensor to be stored in the memory,wherein, if the processor determines that acceleration in a first direction is greater than a first direction threshold for a time longer than a first threshold time, and, if the processor determines that acceleration in a second direction meets at least one condition for determination of an event associated with the second direction, the processor determines that the foot impacts a surface;wherein, after the foot impacts the surface, the processor determines that the foot slips if a difference between an acceleration in a direction perpendicular to the first direction and an acceleration in the first direction is greater than a slip threshold for at least a slip threshold time after a first stance is determined;wherein, after the foot impacts the surface, the processor determines that a swinging foot clips the foot if each of absolute values of each of the maximum differences in acceleration in each of the first direction, a third direction, perpendicular to the first direction, and a fourth direction, perpendicular to the first direction and the third direction, is greater than a clip threshold after a first stance is determined and before a second stance is determined; andwherein, if the processor determines that each of variations of accelerations in the first direction, the third direction, perpendicular to the first direction, and the fourth direction, perpendicular to the first direction and the third direction, are greater than a variations threshold for at least a duration, the processor determines that a fall has occurred. 2. The device of claim 1, wherein the processor determines that the foot impacts the surface at a point when the acceleration in the first direction is at a maximum within a time period after the processor determined that the acceleration in the first direction was greater than the first direction threshold for a time longer than the first threshold time. 3. The device of claim 1, wherein the at least one condition for determination of an event associated with the second direction comprises at least one of: a change in an acceleration in the negative second direction having a magnitude greater than a transient threshold over a transient time period, andan acceleration in the negative second direction having a magnitude greater than an event threshold, the event threshold being greater than the transient threshold. 4. The device of claim 1, wherein, if the processor determines that acceleration in the second direction does not meet the at least one condition for determination of an event associated with the second direction, the processor again determines whether the acceleration in the first direction is greater than the first direction threshold for a time longer than the first threshold time. 5. The device of claim 1, wherein the processor determines a time at which the acceleration in the first direction was greater than the first direction threshold for a time longer than the first threshold time and a time at which the foot impacts the surface, and wherein the processor then implements an ignore phase in which the processor does not analyze data from the at least one sensor for the greater of the time at which the acceleration in the first direction was greater than the first direction threshold for a time longer than the first threshold time plus 250 ms and the time at which the foot impacts the surface plus 125 ms. 6. The device of claim 1, wherein the processor determines a rate of impact of the foot on the surface based on a greatest amount of change in the second direction within a time period after a maximum acceleration in the negative second direction. 7. The device of claim 5, wherein, after the ignore phase, the processor determines a push off of the foot from the surface as the larger of a maximum acceleration in the first direction and a maximum acceleration in the second direction. 8. The device of claim 6, wherein the processor further determines a maximum acceleration in the first direction and a maximum acceleration in the second direction after the maximum acceleration in the negative second direction, and the processor normalizes the greatest amount of change in the second direction within the time period based on at least one of the determined maximum acceleration in the first direction and the determined maximum acceleration in the second direction. 9. A device to determine characteristics of a step, the device comprising: at least one sensor to measure acceleration of a foot in at least two directions;at least one processor to execute instructions stored in a memory and to control acceleration data measured by the at least one sensor to be stored in the memory;the processor determines that a foot has impacted a surface using the acceleration data, thereafter completing a foot stance prior to a following step; andwherein, following the foot stance, if the processor determines that a difference between an acceleration in a second direction perpendicular to the first direction and an acceleration in the first direction is greater than a slip threshold for at least a slip threshold time after the foot stance is determined, the foot is determined to have slipped;wherein, following the foot stance, if the processor determines that each of absolute values of each of the maximum differences in acceleration in each of the first direction, a second direction, perpendicular to the first direction, and a third direction, perpendicular to the first direction and the second direction, is greater than a clip threshold before a new foot stance is determined, then the foot is determined to have clipped; andwherein, following the foot stance, if the processor determines that each of variations of accelerations in the first direction, the third direction, and the second direction, perpendicular to the first direction and the third direction, are greater than a variations threshold for at least a predetermined duration, a fall is determined to have occurred.