Ultra low power actigraphy based on dynamic threshold

摘要

A processor for an activity monitor for a user has a reduced power mode in which it does not process data samples from an accelerometer. A wake up circuit or logic evaluates an output from the accelerometer and determines whether the output exceeds a threshold, indicating a threshold amount of activity of the user. If the threshold is exceeded, the wake up circuit or logic causes the processor to enter an active mode. The processor evaluates samples of the accelerometer in an evaluation period and decides whether to continue in the active mode or return to the reduced power mode. If the user is deemed to be sufficiently active, the processor continues in the active mode. In another aspect, the threshold can be set based on an activity level of the user before the reduced power mode or sensor data such as ambient light level or skin temperature.

主权项

1. An activity monitor, comprising:
an accelerometer adapted to be worn by a user and outputting an activity signal indicative of an activity level of the user; a circuit in communication with the accelerometer and determining whether the activity signal output from the accelerometer exceeds a threshold; and a processor configured to be in communication with the accelerometer and the circuit,
the processor is adapted to process data samples from the accelerometer in an active mode of the processor, and otherwise reduce power consumption of the activity monitor by not transferring the data samples from the accelerometer to the processor,the circuit triggering the processor to enter the active mode, for a minimum period of time, from a reduced power mode when the activity signal output exceeds the threshold, and the minimum period of time is adjustable based on a determination that the user will remain active within the minimum period of time,the processor, upon entering the active mode, configured to evaluate data samples from the accelerometer during an evaluation period, the evaluation period triggered by the circuit detecting the activity signal exceeding the threshold, and the threshold adaptively adjustable based on sensor input, andthe processor, based on the evaluation, configured to determine the activity level of the user, andthe processor, based on the activity level, configured to determine whether to remain in the active mode or to transition to the reduced power mode.