Devices and methods for determining step characteristics
AssigneeZwift, Inc.
InventorsStephen Suydam, Meir Machlin, Jason Kaplan
Life of this patent
Estimating the term…
Abstract
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.
Claims9
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;
- and
- wherein, 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.
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;
- and
- wherein, 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;
- and
- wherein, 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.
Dependencies are inferred from the claim text.