Method and apparatus for assessing driver head pose with a headrest-mounted relative motion sensor

• US 8,184,856 B2
• Filed: 07/24/2008
• Issued: 05/22/2012
• Est. Priority Date: 04/30/2007
• Status: Active Grant

• Current Assignee: Aptiv Technologies AG (Aptiv PLC)
• Original Assignee: Delphi Technologies, Inc. (Aptiv PLC)
• Inventors: Smith, Matthew R., Witt, Gerald J., Dufour, Robert
• Primary Examiner(s): Newman, Michael A
• Application Number:
  US12/220,425
• Publication Number:
  US 20080288143A1
• Time in Patent Office: 1,398 Days
• Field of Search: 382/103, 382/104, 382/106, 382/107, 382/321, 340/438, 340/576, 180/271
• US Class Current: 382/103
• CPC Class Codes: A61B 5/18 for vehicle drivers or machine operators
• CPC Class Codes: B60N 2/002 Seats provided with an occupancy detection means mounted therein or thereon detection means responsive to presence or absence of children B60N2/266
• CPC Class Codes: B60N 2/0244 with logic circuits
• CPC Class Codes: B60N 2/806 movable or adjustable
• CPC Class Codes: B60N 2/829 characterised by their adjusting mechanisms, e.g. electric motors
• CPC Class Codes: B60N 2/865 providing a fore-and-aft movement with respect to the occupant's head
• CPC Class Codes: B60N 2/879 with additional features not related to head-rest positioning, e.g. heating or cooling devices or loudspeakers
• CPC Class Codes: B60R 2021/0048 Head
• CPC Class Codes: B60R 2021/01252 Devices other than bags
• CPC Class Codes: B60R 21/01534 using electromagneticwaves, e.g. infrared
• CPC Class Codes: B60R 21/01552 detecting position of specific human body parts, e.g. face, eyes or hands
• CPC Class Codes: B60W 2540/22 Psychological state; Stress level or workload
• CPC Class Codes: B60W 2540/221 Physiology, e.g. weight, heartbeat, health or special needs
• CPC Class Codes: G06F 2218/00 Aspects of pattern recognition specially adapted for signal processing
• CPC Class Codes: G06V 20/597 Recognising the driver's state or behaviour, e.g. attention or drowsiness
• CPC Class Codes: G06V 40/20 Movements or behaviour, e.g. gesture recognition recognition of facial expressions G06V40/16

Abstract

A relative motion sensor mounted in the headrest of a vehicle driver seat is used to assess the head pose of a vehicle driver and adjust the headrest position to optimize both the safety of the driver and the sensitivity of the relative motion sensor. At the beginning of each ignition cycle, the relative motion sensor is used to adjust the position of the headrest relative to the driver'"'"'s head for optimal driver safety, and the relative motion sensor is oriented to provide optimal sensitivity for head pose assessment when the headrest is positioned for driver safety.

Claims

1. Apparatus for assessing a head pose of a driver supported on a vehicle seat including an adjustable headrest, comprising:

a relative motion sensor mounted on said headrest for sensing a posterior portion of the driver'"'"'s head and producing a signal responsive to motion of the posterior portion of the driver'"'"'s head; and

a processor for processing the signal produced by the relative motion sensor for controlling adjustment of the headrest to provide both optimal driver safety and optimal sensitivity of the relative motion sensor when determining motion of the posterior portion, and assessing whether the driver'"'"'s head pose is forward or non-forward with respect to a vehicle frame of reference, wherein the processor assesses the driver'"'"'s head pose as forward when the motion of the posterior portion is less than a first threshold, a steady head pose condition exists for a period of time that exceeds a second threshold, and a non-forward head pose condition exists for a period of time that exceeds a third threshold.

2. The apparatus of claim 1, where:

the relative motion sensor is an optical sensor, and optical metrics provided by the relative motion sensor are used to infer a proximity of the headrest to the driver'"'"'s head.

3. A method of assessing a head pose of a driver supported on a vehicle seat including an adjustable headrest, comprising the steps of:

providing a relative motion sensor on said headrest for sensing a posterior portion of the driver'"'"'s head and producing a signal responsive to motion of the posterior portion of the driver'"'"'s head;

processing the signal produced by the relative motion sensor for controlling adjustment of the headrest to provide both optimal driver safety and optimal sensitivity of the relative motion sensor when determining motion of the posterior portion; and

processing the signal produced by the relative motion sensor for assessing whether the driver'"'"'s head pose is forward or non-forward with respect to a vehicle frame of reference, wherein the driver'"'"'s head pose is assessed as forward when the motion of the posterior portion is less than a first threshold, a steady head pose condition exists for a period of time that exceeds a second threshold, and a non-forward head pose condition exists for a period of time that exceeds a third threshold.

4. The method of claim 3, where the step of processing the signal produced by the relative motion sensor for controlling adjustment of the headrest includes the steps of:

raising the headrest to a position where the relative motion sensor cannot sense the driver'"'"'s head;

lowering the headrest until the relative motion sensor senses the driver'"'"'s head; and

lowering the headrest an additional prescribed amount.

5. The method of claim 4, including the step of:

orienting the relative motion sensor on the headrest so that optimal sensitivity of the relative motion sensor occurs when the headrest has been lowered the additional prescribed amount.

6. The method of claim 3, including the steps of:

sensing a proximity of the headrest to the driver'"'"'s head; and

adjusting a fore/aft position of the headrest to properly position the headrest with respect to the driver'"'"'s head.

7. The method of claim 6, where:

the relative motion sensor is an optical sensor, and the proximity of the headrest to the driver'"'"'s head is inferred from optical metrics provided by the relative motion sensor.

8. The method of claim 4, where the step of raising the headrest to a position where the relative motion sensor cannot sense the driver'"'"'s head includes the steps of:

raising the headrest while monitoring the signal produced by the relative motion sensor; and

discontinuing the raising of the headrest when the relative motion sensor cannot sense the driver'"'"'s head or the headrest has been raised to a maximum height.