Intelligent activity monitor

Abstract

Apparatuses and methods are disclosed for identifying with a single, small activity monitor a particular type of activity from among a plurality of different activities. The monitor may include a multi-axis accelerometer and microcontroller configured to combine and process accelerometer data so as to generate features representative of an activity. The features may be processed to identify a particular activity (e.g., running, biking, swimming) from among a plurality of different activities that may include activities not performed by a human subject. The activity monitor may be configured to further process the features to calculate various parameters characterizing the activity (e.g., duration of activity, total steps, distance traveled, intensity of activity, and calories burned). The monitor may identify a location on a subject where the monitor is worn, and provide a measure of the quality of the processed data or calculated parameters. The activity monitor may be configured to execute a self-calibration routine for an activity that is based on a temporary cessation of motion during the activity. Low energy paradigms are used to extend battery-powered operation of the activity monitor.

What is claimed is: 
     
         1 . An activity monitor comprising:
 an accelerometer; and   a microprocessor, wherein the microprocessor is configured to compute derivatives of first acceleration data received from a first axis of the accelerometer to form first acceleration-derivative values when the accelerometer is supported by a subject in motion and to process the acceleration-derivative values to identify an activity of the subject.   
     
     
         2 . The activity monitor of  claim 1 , further comprising:
 a power source;   a transceiver; and   power-management circuitry configured to sense an activity level of the activity monitor and apply power to or remove power from at least the microprocessor responsive to the sensed activity level of the activity monitor.   
     
     
         3 . The activity monitor of  claim 1 , wherein the activity monitor includes a strap or a clip for attaching the activity monitor to an article of clothing or strapping the activity monitor to a subject. 
     
     
         4 . The activity monitor of  claim 1 , wherein the identified activity is one activity from among a plurality of activities identifiable by the activity monitor, the plurality of activities comprising two or more activities selected from the following group: walking, running, biking, swimming, using a type of exercise machine, rowing, cross-country skiing, jumping-jacks, sit-ups, push-ups, pull-ups, and jumping rope. 
     
     
         5 . The activity monitor of  claim 4 , wherein the microprocessor is further configured to identify, from the processed acceleration-derivative values, a falsified human activity and/or an activity that a human is not capable of performing. 
     
     
         6 . The activity monitor of  claim 1 , wherein the accelerometer is a multi-axis accelerometer and the microprocessor is further configured to compute derivatives of acceleration data received from each axis of the multi-axis accelerometer to form multi-axis acceleration-derivative values and to combine the multi-axis acceleration-derivative values according to the following relation: 
       
         
           
             
               
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         where D n  represents a combined acceleration-derivative value and D i,n  represents an n th  computed acceleration-derivative value for an i th  axis of the multi-axis accelerometer. 
       
     
     
         7 . The activity monitor of  claim 1 , wherein the microprocessor is configured to:
 form the first acceleration-derivative values into a first stream of data; and   identify from the first stream of data at least one characteristic feature by extracting peak values and/or peak widths from the first data stream.   
     
     
         8 . The activity monitor of  claim 1 , wherein the microprocessor is configured to:
 form the first acceleration-derivative values into a first stream of data; and   identify from the first stream of data at least one characteristic feature by determining maximum and minimum values of the first data stream.   
     
     
         9 . The activity monitor of  claim 1 , wherein the microprocessor is further configured to:
 form the first acceleration-derivative values into a first stream of data;   process the first stream of data to identify at least one characteristic feature of the first stream of data;   provide the at least one characteristic feature to a fuzzy inference engine; and   analyze the at least one characteristic feature with the fuzzy inference engine to identify one activity from among a plurality of different activities.   
     
     
         10 . The activity monitor of  claim 9 , wherein the microprocessor is further configured to:
 provide the first acceleration data and/or the at least one characteristic feature to one of a plurality of activity analysis engines based on the identification of the one activity; and   calculate, with the one activity analysis engine, parameters characterizing the activity.   
     
     
         11 . The activity monitor of  claim 10 , wherein the parameters includes one or more parameters selected from the following group: a measure of pace of the activity, a measure of energy expended during the activity, a measure of distance traveled during the activity, and a duration of the activity. 
     
     
         12 . The activity monitor of  claim 11 , wherein the microprocessor is further configured to calculate at least one quality metric for one or more of the parameters, the at least one quality metric indicating a reliability of the one or more of the parameters. 
     
     
         13 . The activity monitor of  claim 1 , wherein the microprocessor is further configured to identify a location at which the activity monitor is supported by the subject and to select a data processing algorithm based on the identified location. 
     
     
         14 . A method comprising:
 computing, by at least one microprocessor, derivatives of first acceleration data received from an accelerometer to form first acceleration-derivative values, the first acceleration data being representative of acceleration along a first axis of the accelerometer; and   processing the first acceleration-derivative values to identify an activity sensed by the accelerometer.   
     
     
         15 . The method of  claim 14 , further comprising:
 computing derivatives of at least second acceleration data received from the accelerometer to form at least second acceleration-derivative values, the at least second acceleration data being representative of acceleration along at least a second axis of the accelerometer; and   combining the first and at least second acceleration-derivative values according to the following relation:   
       
         
           
             
               
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       where D n  represents a combined acceleration-derivative value and D i,n  represents an n th  computed acceleration-derivative value for an i th  axis of the accelerometer. 
     
     
         16 . The method of  claim 14 , wherein the accelerometer is disposed in an activity monitor and the method further comprises clipping the activity monitor to an article of clothing or attaching the activity monitor to a subject. 
     
     
         17 . The method of  claim 14 , further comprising:
 forming a first data stream of the first acceleration-derivative values over a first period of time;   identifying at least one characteristic feature of the first data stream;   providing the at least one characteristic feature to a fuzzy inference engine; and   analyzing the at least one characteristic feature with the fuzzy inference engine to identify one activity from among a plurality of different activities.   
     
     
         18 . The method of  claim 17 , wherein the identifying at least one characteristic feature comprises extracting peak values and/or peak widths from the first data stream. 
     
     
         19 . The method of  claim 17 , wherein the identifying at least one characteristic feature comprises determining maximum and minimum values of the first data stream. 
     
     
         20 . The method of  claim 17 , wherein the identifying at least one characteristic feature comprises calculating an average value of acceleration from the first acceleration data for the first period of time. 
     
     
         21 . The method of  claim 17 , wherein the plurality of different activities include two or more activities selected from the following group: walking, running, biking, swimming, using a type of exercise machine, rowing, cross-country skiing, jumping-jacks, sit-ups, push-ups, pull-ups, and jumping rope. 
     
     
         22 . The method of  claim 17 , wherein the plurality of different activities include falsified human activities. 
     
     
         23 . The method of  claim 17 , further comprising:
 determining that the at least one characteristic feature is representative of an activity not recognized by the fuzzy inference engine; and   receiving machine-readable instructions and data enabling the fuzzy inference engine to subsequently identify an activity corresponding to the at least one characteristic feature.   
     
     
         24 . The method of  claim 17 , wherein the fuzzy inference engine uses historical data specific to a user in evaluating the at least one characteristic feature to identify the one activity from among the plurality of different activities. 
     
     
         25 . The method of  claim 17 , further comprising:
 providing the first acceleration data and/or the at least one characteristic feature to one of a plurality of activity analysis engines based on the identification of the one activity; and   calculating, with the one activity analysis engine, parameters characterizing the activity.   
     
     
         26 . The method of  claim 25 , wherein the parameters includes one or more parameters selected from the following group: a measure of pace of the activity, a measure of energy expended during the activity, a measure of distance traveled during the activity, and a duration of the activity. 
     
     
         27 . The method of  claim 25 , further comprising calculating at least one quality metric for one or more of the parameters, the at least one quality metric indicating a reliability of the one or more of the parameters.