Apparatus and method for postural assessment while performing cognitive tasks

• US 20040222892A1
• Filed: 05/06/2004
• Published: 11/11/2004
• Est. Priority Date: 05/06/2003
• Status: Active Grant

• Current Assignee: University of Pittsburgh of The Commonwealth System of Higher Education
• Original Assignee: University of Pittsburgh of The Commonwealth System of Higher Education
• Inventors: Balaban, Carey David, Redfern, Mark Steven
• Granted Patent: US 7,109,872 B2
• Time in Patent Office: Days
• US Class Current: 340/573.7
• CPC Class Codes: A61B 2503/22 Motor vehicles operators, e.g. drivers, pilots, captains
• CPC Class Codes: A61B 2560/0242 adapted to measure environmental factors, e.g. temperature, pollution
• CPC Class Codes: A61B 5/1116 Determining posture transitions
• CPC Class Codes: A61B 5/16 Devices for psychotechnics using teaching or educational appliances G09B1/00 - G09B7/00; Testing reaction times ; Devices for evaluating the psychological state
• CPC Class Codes: A61B 5/18 for vehicle drivers or machine operators
• CPC Class Codes: A61B 5/6814 Head
• CPC Class Codes: A61B 5/6823 Trunk, e.g., chest, back, abdomen, hip
• CPC Class Codes: A61B 5/6891 Furniture
• CPC Class Codes: A61B 5/6892 Mats

Abstract

A postural assessment chair provides a means for monitoring the posture of an individual seated thereon, and correlating changes in the individual'"'"'s posture, along with indicia of movement of the chair itself and the cognitive workload of the individual, to determine the mental engagement of the individual.

Claims

1. A postural assessment chair, comprising:

a seat;

a back;

means for sensing postural changes of a person seated on the chair; and

means for analyzing postural changes to determine a level of mental engagement from information about postural changes of the person.

2. The chair according to claim 1, wherein the means for sensing postural changes include a pressure sensor array having a plurality of sensors disposed on at least one location selected from the group consisting of the seat and the back.

3. The chair according to claim 2, wherein the means for analyzing postural changes include:

means for monitoring a pressure sensed at each sensor within the array;

means for calculating a rate of change in pressure at each sensor;

means for calculating a standard deviation of the rate of change in pressure across all sensors; and

means for comparing the standard deviation to a predetermined threshold.

4. The chair according to claim 2, wherein the means for analyzing postural changes include:

means for monitoring a pressure sensed at each sensor within the array;

means for comparing a pressure distribution across the pressure sensor array with predetermined pressure distributions.

5. The chair according to claim 2, wherein the means for analyzing postural changes include:

means for monitoring a pressure sensed at each sensor within the array;

means for determining a midline separating the pressure distribution into a right and left side;

means for determining a center of pressure on each side of the midline; and

means for monitoring changes in the center of pressure on each side of the midline.

6. The chair according to claim 1, wherein the means for sensing postural changes include a transmitter disposed on or adjacent to the chair, a reference position and orientation sensor disposed on the back, and at least one position sensor disposed on a head or a torso of the person seated on the chair.

7. The chair according to claim 6, wherein the position sensor is selected from the group consisting of magnetic sensors and ultrasonic sensors.

8. The chair according to claim 6, wherein the means for analyzing postural changes include:

means for monitoring changes in position of the position sensor; and

means for comparing changes in position of the position sensor to predetermined patterns of movement.

9. The chair according to claim 6, wherein the means for analyzing postural changes include:

means for monitoring changes in position of the position sensor;

means for monitoring an amount of cognitive work remaining to be performed by the person;

means for correlating the position of the position sensor with the work remaining to be performed;

means for determining whether the correlation of sensor position with work remaining falls below a predetermined threshold; and

means for comparing the sensor position with predetermined sensor movement patterns if the correlation of sensor position with work remaining falls below the predetermined threshold.

10. The chair according to claim 6, wherein the means for analyzing postural changes include:

means for monitoring changes in position of the position sensor;

means for calculating an exponential response based on changes in position with respect to time;

means for calculating a root mean square of the exponential response; and

means for comparing the root mean square to a magnitude of the exponential response.

11. The chair according to claim 1, wherein the means for sensing postural changes include a motion sensor disposed on the chair.

12. The chair according to claim 11, wherein the means for analyzing postural changes include means for comparing postural changes of a person seated in the chair with motions detected by the motion sensor to determine whether the person is properly compensating for motions of the chair.

13. A method of determining a level of cognitive engagement of a person performing seated work, the method comprising:

providing sensors structured to detect postural changes of the person;

comparing the postural changes to information selected from the group consisting of known thresholds, the level of cognitive work remaining, and predetermined postural patterns to determine the level of cognitive engagement of the person.

14. The method according to claim 13, wherein the step of providing sensors structured to detect postural changes includes providing a pressure sensor array having a plurality of sensors disposed on at least one location selected from the group consisting of the seat and the back.

15. The method according to claim 14, wherein the step of comparing the postural changes to information selected from the group consisting of known thresholds, the current cognitive workload (e.g., number of queued tasks), the level of cognitive work remaining, and predetermined postural patterns to determine the level of cognitive engagement of the person includes:

monitoring a pressure sensed at each sensor within the array;

calculating a rate of change in pressure at each sensor;

calculating a standard deviation of the rate of change in pressure across all sensors; and

means for comparing the standard deviation to a predetermined threshold.

16. The method according to claim 14, wherein the step of comparing the postural changes to information selected from the group consisting of known thresholds, the level of cognitive work remaining, and predetermined postural patterns to determine the level of cognitive engagement of the person includes:

monitoring a pressure sensed at each sensor within the array;

comparing a pressure distribution across the pressure sensor array with predetermined pressure distributions.

17. The method according to claim 14, wherein the step of comparing the postural changes to information selected from the group consisting of known thresholds, the level of cognitive work remaining, and predetermined postural patterns to determine the level of cognitive engagement of the person includes:

monitoring a pressure sensed at each sensor within the array;

determining a midline separating the pressure distribution into a right and left side;

determining a center of pressure on each side of the midline; and

monitoring changes in the center of pressure on each side of the midline.

18. The method according to claim 13, wherein the step of providing sensors structured to detect postural changes includes:

providing a transmitter disposed on or adjacent to the chair;

providing a reference position and orientation sensor disposed on the back; and

providing at least one position sensor disposed on a head or a torso of the person seated on the chair.

19. The method according to claim 18, wherein the step of comparing the postural changes to information selected from the group consisting of known thresholds, the level of cognitive work remaining, and predetermined postural patterns to determine the level of cognitive engagement of the person includes:

monitoring changes in position of the position sensor; and

comparing changes in position of the position sensor to predetermined patterns of movement.

20. The method according to claim 18, wherein the step of comparing the postural changes to information selected from the group consisting of known thresholds, the level of cognitive work remaining, and predetermined postural patterns to determine the level of cognitive engagement of the person includes:

monitoring changes in position of the position sensor;

monitoring an amount of cognitive work remaining to be performed by the person;

correlating the position of the position sensor with the work remaining to be performed;

determining whether the correlation of sensor position with work remaining falls below a predetermined threshold; and

comparing the sensor position with predetermined sensor movement patterns if the correlation of sensor position with work remaining falls below the predetermined threshold.

21. The method according to claim 18, wherein the step of comparing the postural changes to information selected from the group consisting of known thresholds, the level of cognitive work remaining, and predetermined postural patterns to determine the level of cognitive engagement of the person includes:

monitoring changes in position of the position sensor;

calculating an exponential response based on changes in position with respect to time;

calculating a root mean square of the exponential response; and

comparing the root mean square to a magnitude of the exponential response.

22. The method according to claim 13, wherein the step of providing sensors structured to detect postural changes includes providing a motion sensor disposed on the chair.

23. The method according to claim 22, wherein the step of comparing the postural changes to information selected from the group consisting of known thresholds, the current cognitive workload, number of queued tasks, the level of cognitive work remaining, and predetermined postural patterns to determine the level of cognitive engagement of the person includes comparing postural changes of a person seated in the chair with motions detected by the motion sensor to determine whether the person is properly compensating for motions of the chair.