Method and system for measuring energy expenditure and foot incline in individuals
A method and system for measuring energy expenditure of individuals by measuring force from a plurality of foot-borne force sensitive resistors and calculating incline from a foot-borne tri-axial accelerometer.
1. A system for analyzing motion of a user, comprising:
a tri-axial accelerometer affixed to a user's foot;
a processor coupled to the tri-axial accelerometer; and
a computer memory coupled to the processor, the computer memory comprising computer executable instructions that when executed by the processor cause the processor to perform the following:
a) collecting accelerometer data from the tri-axial accelerometer;
b) determining incline during stance phase based on the accelerometer data from the tri-axial accelerometer using an electronic processor;
c) determining stance phase based on the accelerometer data from the tri-axial accelerometer using the electronic processor; and
d) determining an energy expenditure of the individual based on the inclination of the shoe with respect to the ground over a period of time using the electronic processor.
2. The system in accordance with claim 1 , further comprising:
determining energy expenditure of the individual based on the accelerometer data from the tri-axial accelerometer using the electronic processor.
3. The system in accordance with claim 1 , further comprising:
affixing a plurality of force sensitive resistors with respect to the user's foot;
collecting force data from the plurality of force sensitive resistors; and
determining stance phase based on the force data from the plurality of force sensitive resistors using the electronic processor.
4. The system in accordance with claim 3 , further comprising:
determining an energy expenditure of the individual based on the force applied to the shoe and the inclination of the shoe with respect to the ground over a period of time using the electronic processor.
5. The system in accordance with claim 1 , wherein determining stance phase further includes determining a magnitude of acceleration vector utilizing the equation:
A
⇀
=
A
x
2
+
A
y
2
+
A
z
2
where A x , A y and A z are magnitudes of acceleration measured by the tri-axial accelerometer in x, y and z directions, and A is the magnitude of the acceleration vector; and wherein the magnitude of total acceleration being substantially equal to 1 g during stance phase.
6. The system in accordance with claim 1 , further comprising:
estimating incline utilizing the equation:
θ
=
sin
-
1
(
A
x
+
A
y
2
(
A
x
2
+
A
y
2
+
A
z
2
)
)
where A x , A y and A z are magnitudes of acceleration measured by the tri-axial accelerometer in x, y and z directions, respectively, and θ is the angle on incline.
7. The system in accordance with claim 1 , further comprising:
determining offset between the shoe and the sensor board when the system is initialized and the foot is on level ground utilizing the equation:
θ
o
=
sin
-
1
(
A
xo
+
A
yo
2
(
A
xo
2
+
A
yo
2
+
A
zo
2
)
)
where A xo , A yo and A zo are magnitudes of acceleration measured by the tri-axial accelerometer in x, y and z directions, respectively, measured when the foot is initially flat on level ground, and θ o is the offset angle between the shoe and the sensor board; and
determining incline during gait utilizing the equation:
θ
=
sin
-
1
(
A
x
+
A
y
2
(
A
x
2
+
A
y
2
+
A
z
2
)
)
-
θ
o
where A x , A y and A z are magnitudes of acceleration measured by the tri-axial accelerometer in x, y and z directions, respectively, measured when the foot is in stance phase, and θ is the angle of incline.
8. The system in accordance with claim 1 , further comprising:
positioning a toe piece of an insole with at least one force sensitive resistor at a toe of the shoe;
positioning a heel piece of the insole with at least one force sensitive resistor at a heel of the shoe; and
positioning a middle piece of the insole with the tri-axial accelerometer in the shoe between the toe and heel pieces.
9. A system for measuring activity in an individual, comprising:
a multi-sensor insole disposed in a shoe including a plurality of force sensitive resistors and a tri-axial accelerometer;
a processor coupled to the tri-axial accelerometer; and
a computer memory coupled to the processor, the computer memory comprising computer executable instructions that when executed by the processor cause the processor to perform the following:
a) collecting data from the multi-sensor insole, including force data from the plurality of force sensitive resistors and accelerometer data from the tri-axial accelerometer;
b) analyzing the data from the sensors of the multi-sensor insole with an electronic processor to determine the energy expenditure of the individual based on the force data and inclination of the shoe with respect to the ground during stance phase over a period of time; and
c) determining stance phase based on the force data from the plurality of force sensitive resistors.
10. The system in accordance with claim 9 , further comprising:
estimating the inclination utilizing the equation:
θ
=
sin
-
1
(
A
x
+
A
y
2
(
A
x
2
+
A
y
2
+
A
z
2
)
)
where A x , A y and A z are magnitudes of acceleration measured by the tri-axial accelerometer in x, y and z directions, respectively, and θ is the angle of inclination.
11. The system in accordance with claim 10 , further comprising:
determining offset between the shoe and the sensor board when the system is initialized and the foot is on level ground utilizing the equation:
θ
o
=
sin
-
1
(
A
xo
+
A
yo
2
(
A
xo
2
+
A
yo
2
+
A
zo
2
)
)
where A xo , A yo and A zo are magnitudes of acceleration measured by the tri-axial accelerometer in x, y and z directions, respectively, measured when the foot is initially flat on level ground, and θ o is the offset angle between the shoe and the sensor board; and
determining incline during gait utilizing the equation:
θ
=
sin
-
1
(
A
x
+
A
y
2
(
A
x
2
+
A
y
2
+
A
z
2
)
)
-
θ
o
where A x , A y and A z are magnitudes of acceleration measured by the tri-axial accelerometer in x, y and z directions, respectively, measured when the foot is in stance phase, and θ is the angle of incline.
12. The system in accordance with claim 11 , further comprising:
determining stance phase based on the force data and the accelerometer data and utilizing the equations:
A
⇀
=
A
x
2
+
A
y
2
+
A
z
2
where A x , A y and A z are magnitudes of acceleration measured by the tri-axial accelerometer in x, y and z directions, and A is the magnitude of the acceleration vector; and wherein the magnitude of total acceleration being substantially equal to 1 g during stance phase.
13. The system in accordance with claim 9 , further comprising:
an insole disposable in the shoe and configured to contain and position the sensor array across a sole footprint of the shoe.
14. The system in accordance with claim 13 , wherein the insole further comprises:
a toe piece with at least one force sensitive resistor configured to be positioned at a toe of the shoe;
a heel piece with at least one force sensitive resistor configured to be positioned at a heel of the shoe; and
a middle piece between the toe and heel pieces; and
the toe, heel and middle pieced being held together but movably positioned with respect to one another.
15. In a computing environment, a non transitory computer readable storage medium storing computer executable instructions which, in a system including a tri-axial accelerometer affixed to a user's foot and a processor coupled to the tri-axial accelerometer, when executed by a computing processor, implement the following acts:
a) collecting accelerometer data from the tri-axial accelerometer;
b) determining incline during stance phase based on the accelerometer data from the tri-axial accelerometer using an electronic processor;
c) determining stance phase based on the accelerometer data from the tri-axial accelerometer; and
d) determining an energy expenditure of the individual based on the inclination of the shoe with respect to the ground over a period of time.
16. The computer readable storage medium in accordance with claim 15 , further comprising:
determining energy expenditure of the individual based on the accelerometer data from the tri-axial accelerometer using the electronic processor.
17. The computer readable storage medium in accordance with claim 15 , in the system including the tri-axial accelerometer affixed to the user's foot and the processor coupled to the tri-axial accelerometer and including a plurality of force sensitive resistors affixed to the user's foot, further comprising:
collecting force data from the plurality of force sensitive resistors; and
determining stance phase based on the force data from the plurality of force sensitive resistors using the electronic processor.
18. The computer readable storage medium in accordance with claim 17 , further comprising:
determining an energy expenditure of the individual based on the force applied to the shoe and the inclination of the shoe with respect to the ground over a period of time using the electronic processor.
19. The computer readable storage medium in accordance with claim 15 , wherein determining stance phase further includes determining a magnitude of acceleration vector utilizing the equation:
A
⇀
=
A
x
2
+
A
y
2
+
A
z
2
where A x , A y and A z are magnitudes of acceleration measured by the tri-axial accelerometer in x, y and z directions, and A is the magnitude of the acceleration vector; and wherein the magnitude of total acceleration being substantially equal to 1 g during stance phase.
20. The computer readable storage medium in accordance with claim 15 , further comprising:
estimating incline utilizing the equation:
θ
=
sin
-
1
(
A
x
+
A
y
2
(
A
x
2
+
A
y
2
+
A
z
2
)
)
where A x , A y and A z are magnitudes of acceleration measured by the tri-axial accelerometer in x, y and z directions, respectively, and θ is the angle on incline.
21. The computer readable storage medium in accordance with claim 15 , further comprising:
determining offset between the shoe and the sensor board when the system is initialized and the foot is on level ground utilizing the equation:
θ
o
=
sin
-
1
(
A
xo
+
A
yo
2
(
A
xo
2
+
A
yo
2
+
A
zo
2
)
)
where A xo , A yo and A zo are magnitudes of acceleration measured by the tri-axial accelerometer in x, y and z directions, respectively, measured when the foot is initially flat on level ground, and θ o is the offset angle between the shoe and the sensor board; and
determining incline during gait utilizing the equation:
θ
=
sin
-
1
(
A
x
+
A
y
2
(
A
x
2
+
A
y
2
+
A
z
2
)
)
-
θ
o
where A x , A y and A z are magnitudes of acceleration measured by the tri-axial accelerometer in x, y and z directions, respectively, measured when the foot is in stance phase, and θ is the angle of incline.