Apple Inc.
Estimating Caloric Expenditure Based on Center of Mass Motion and Heart Rate

Abstract:

Embodiments are disclosed for estimating caloric expenditure based on center of mass motion and heart rate. In an embodiment, a method comprises: obtaining acceleration and rotation rate of a wearable device worn on a limb of a user; transforming the acceleration and rotation rate into an inertial frame; determining a vertical component of acceleration, rotation rate magnitude and vertical component of rotational acceleration due to limb rotation; determining a work rate (WR) based caloric expenditure based on the vertical component of acceleration, rotation rate magnitude and a correlation coefficient that measures a correlation between the vertical component of acceleration and the vertical component of rotational acceleration; obtaining heart rate (HR) data from a heart rate sensor of the wearable device; determining an HR based caloric expenditure based on the HR data; and fusing, the WR based caloric expenditure with the HR based caloric expenditure to get a fused caloric expenditure.