Foot pad device and method of obtaining weight data

• US 20100211355A1
• Filed: 02/09/2010
• Published: 08/19/2010
• Est. Priority Date: 02/09/2009
• Status: Active Grant

• Current Assignee: AlterG, Inc.
• Original Assignee: AlterG, Inc.
• Inventors: Arnold, Edith, Jardine, Robert L., Smith, Jonathan, Horst, Robert W.
• Granted Patent: US 8,639,455 B2
• Time in Patent Office: Days
• US Class Current: 702/173
• CPC Class Codes: A61B 5/1036 Measuring load distribution, e.g. podologic studies
• CPC Class Codes: A61B 5/1038 Measuring plantar pressure during gait
• CPC Class Codes: G01G 19/44 for weighing persons
• CPC Class Codes: G01G 23/3735 using a digital network

Abstract

A foot pad device and a method of obtaining weight data from a force sensor in a foot pad worn by a user engaging in a footstep, including placing the force sensor under the ball of the foot of the user and/or the heel of the foot of the user; receiving an entered patient weight value for the user; collecting force data from the force sensor; calculating a weight value based on the collected force data and a scaling and/or offset parameter; comparing the calculated weight value to the entered patient weight value; comparing the calculated weight value to zero; adjusting the scaling and/or offset parameter; and repeating the steps periodically. The method may include comparing the collected force data to a functionality indication range, flagging the force sensor if the collected force data is outside the functionality indication range, and disregarding force data from the flagged force sensor.

Claims

1. A method of obtaining weight data from a force sensor in a foot pad worn by a user engaging in a footstep, comprising the steps of:

a. placing a force sensor under at least one of the ball of the foot of the user and the heel of the foot of the user;

b. receiving an entered patient weight value for the user;

c. collecting force data from the force sensor;

d. calculating a weight value based on the collected force data and a scaling parameter that scales the collected force data;

e. comparing the calculated weight value to the entered patient weight value in a first comparison;

f. comparing the calculated weight value to zero in a second comparison;

g. adjusting the scaling parameter based on at least one of the first and second comparisons; and

h. repeating Steps (c) through (g) periodically.

2. The method of claim 1, wherein the step of calculating a weight value includes calculating a weight value based on the collected force data and the scaling parameter that includes a gain value.

3. The method of claim 2, wherein the step of adjusting the scaling parameter includes decreasing the gain value if the calculated weight value is greater than the entered patient weight value.

4. The method of claim 2, further comprising the step of receiving information that signals a completion of the footstep by the user, wherein the step of adjusting the scaling parameter includes increasing the gain value if the received information signals a completion of the footstep and the maximum of the calculated weight values during the footstep is less than the entered patient weight value.

5. The method of claim 1, wherein the step of calculating a weight value includes calculating a weight value based on the collected force data and the scaling parameter that includes an offset value.

6. The method of claim 5, further comprising the step of receiving information that signals a completion of the footstep by the user, wherein the step of adjusting the scaling parameter includes decreasing the offset value if the received information signals a completion of the footstep and the minimum of the calculated weight values during the footstep is greater than zero.

7. The method of claim 5, wherein the step of adjusting the offset value includes increasing the offset value if the calculated weight value is less than zero.

8. The method of claim 1, further comprising the step of applying the calculated weight value to selectively control an actuator of a mobility assistance device to enhance the mobility of a leg to the user.

9. A method of obtaining weight data from a force sensor in a foot pad worn by a user, comprising the steps of:

a. placing a plurality of force sensors under a foot of the user;

b. collecting force data from the force sensor;

c. comparing the collected force data to a functionality indication range;

d. if the collected force data is outside the functionality indication range,

flagging the force sensor as nonfunctional; and

disregarding force data from the flagged force sensor;

e. calculating a weight value based on the collected force data; and

f. repeating Steps (c) through (e) periodically.

10. The method of claim 9, wherein the step of placing a plurality of force sensors under a foot of the user includes placing at least one of the plurality of force sensors under at least one of the ball of the foot and the heel of the foot.

11. The method of claim 9, wherein the step of repeating Steps (c) through (e) is performed for each of the plurality of force sensors in the foot pad.

12. The method of claim 9, wherein the step of repeating Steps (c) through (e) continues to be performed when one force sensor has been flagged.

13. The method of claim 9, further comprising the step of tracking the number of flagged force sensors, wherein the step of repeating Steps (c) through (e) ceases to be performed when a predetermined number of force sensors have been tracked as flagged force sensors.

14. The method of claim 9, further comprising the step of applying the calculated weight value to selectively control an actuator of a mobility assistance device to enhance the mobility of a leg of the user.

15. A foot pad device worn on the foot of a user for obtaining weight data comprising:

a foot pad, defining at least one of a ball region located under the ball of the foot of the user and a heel region located under the heel of the foot of the user;

wherein the foot pad is selected from a group of foot pads of different sizes;

a plurality of force sensors that provide force data, wherein at least a portion of the plurality of force sensors is located in at least one of the ball region and the heel region;

sensor electronics, coupled to the plurality of force sensors, that condition the force data to be within a conditioned force data range;

wherein the sensor electronics include a flexible circuit with a plurality of force sensor connection paths adapted to transmit force data from the plurality of force sensors and defining a plurality of applicable sensor positions;

wherein the plurality of force sensors are located in at least a selected portion of the plurality of applicable sensor positions; and

a processor that calculates a weight value based on the conditioned force data.

16. The foot pad device of claim 15, wherein the selected portion of the plurality of applicable sensor positions are selected based on the size of the foot pad.

17. The foot pad device of claim 15, wherein the sensor electronics include a resistor of a selected value that is connected relative to each connected force sensor connection path;

wherein the resistor value characterizes the collected force data.

18. The foot pad device of claim 17, wherein the resistor value is associated with the size of the foot pad.

19. The foot pad device of claim 18, wherein the processor identifies the foot pad size by analyzing the characterized force data.

20. The foot pad device of claim 17, wherein the processor flags the force sensor as nonfunctional if the force data is outside of a functionality indication range and disregards force data from the flagged force sensor.