Adjustment system for an occupant support

1. An occupant-support base comprising:

a seat pad configured to support an occupant above a seat frame, the seat pad including a generally fixed portion fixed in position relative to the seat frame and a movable portion movable relative to the seat frame,

a pad-extension system configured to move the movable portion of the seat pad relative to the seat frame between a retracted configuration in which the seat pad defines an occupant-support surface with a first length and an extended configuration in which the seat pad defines an occupant support surface with a second length that is greater than the first length, and

an extension-control system coupled to the pad-extension system and configured to sense a position of the occupant relative to the seat pad and send a command signal to cause the pad-extension system to move the movable portion of the pad based on the position of the occupant relative to the seat pad;

wherein the extension-control system includes a sensor unit configured to provide a plurality of sensor signals associated with the position of the occupant relative to the seat pad and a controller configured to receive the sensor signals, compare the sensor signals, and send the command signal to the pad-extension system using the compared sensor signals; and

wherein the sensor unit includes a plurality of sensors arranged along a curvature of the seat pad that extends from the generally fixed portion of the seat pad along the movable portion of the seat pad.

2. The occupant-support base of claim 1 , wherein the plurality of sensors includes a first sensor configured to determine a first value, a second sensor configured to determine a second value, a third sensor configured to determine a third value, a fourth sensor configured to determine a fourth value, and a fifth sensor configured to determine a fifth value.

3. The occupant-support base of claim 2 , wherein the controller is configured to calculate a first ratio based on the first and second values, a second ratio based on the second and third values, a third ratio based on the third and fourth values, and a fourth ratio based on the fourth and fifth values.

4. The occupant-support base of claim 3 , wherein the controller is configured to send the command signal to cause the pan-extension system to extend the movable portion of the seat pad when the first ratio is less than the fourth ratio plus a predetermined value of about 0.5.

5. The occupant-support base of claim 3 , wherein the controller is configured to send the command signal to cause the pan-extension system to retract the movable portion of the seat pad when the first ratio is less than the second ratio plus a predetermined value of about 0.9.

6. The occupant-support base of claim 3 , wherein the controller is configured to send the command signal to the pan-extension system to cause the pan-extension system to move the movable portion of the seat pad until:

(a) the first ratio is less than the second ratio, plus a predetermined value of about 0.7;

(b) the second ratio is less than the third ratio; and

(c) the third ratio is greater than the fourth ratio.

7. The occupant-support base of claim 1 , wherein the plurality of sensors includes a first sensor, second sensor, third sensor, fourth sensor, and fifth sensor, and the first and second sensors are positioned on the movable portion of the seat pad, the third sensor is positioned between the movable portion of the seat pad and the generally fixed portion of the seat pad, and the fourth and fifth sensors are positioned on the generally fixed portion of the seat pad.

8. The occupant-support base of claim 7 , wherein the first sensor is positioned adjacent to the second sensor and is configured to determine a first value and the second sensor is configured to determine a second value and the controller is configured to calculate a first ratio based on the first and second values.

9. The occupant-support base of claim 8 , wherein the second sensor is positioned between the first sensor and the third sensor and the third sensor is configured to determine a third value and the controller is configured to calculate a second ratio based on the second and third values.

10. The occupant-support base of claim 9 , wherein the third sensor is positioned between the second sensor and the fourth sensor and the fourth sensor is configured to determine a fourth value and the controller is configured to calculate a third ratio based on the third and fourth values.

11. The occupant-support base of claim 10 , wherein the fourth sensor is positioned between the third sensor and the fifth sensor and the fifth sensor is configured to determine a fifth value and the controller is configured to calculate a fourth ratio based on the fourth and fifth values.

12. The occupant-support base of claim 1 , wherein the plurality of sensors includes a first sensor, a second sensor, a third sensor, a fourth sensor, and a fifth sensor coupled to the movable portion of the seat pad in spaced-apart relation to one another.

13. The occupant-support base of claim 12 , wherein the first sensor is positioned adjacent to the second sensor and is configured to determine a first value and the second sensor is configured to determine a second value and the controller is configured to calculate a first ratio based on the first and second values.

14. The occupant-support base of claim 13 , wherein the second sensor is positioned between the first sensor and the third sensor and the third sensor is configured to determine a third value and the controller is configured to calculate a second ratio based on the second and third values.

15. The occupant-support base of claim 14 , wherein the third sensor is positioned between the second sensor and the fourth sensor and the fourth sensor is configured to determine a fourth value and the controller is configured to calculate a third ratio based on the third and fourth values.

16. The occupant-support base of claim 15 , wherein the fourth sensor is positioned between the third sensor and the fifth sensor and the fifth sensor is configured to determine a fifth value and the controller is configured to calculate a fourth ratio based on the fourth and fifth values.

17. The occupant-support base of claim 1 , wherein the plurality of sensors includes a first sensor configured to determine a first value, a second sensor configured to determine a second value, and a third sensor configured to determine a third value, the controller is configured to calculate a first ratio based on the first and second values and a second ratio based on the second and third ratios, and the controller is configured to send the command signal to cause the pad-extension system to extend the movable portion of the seat pad when the first ratio is less than the second ratio plus a predetermined value.

18. The occupant-support base of claim 1 , wherein the pad-extension system is a cushion-length adjuster for a headrest.