Automatically adjusting head restraint system

A headrest positioning system for automatically adjusting the position of a headrest of a vehicle seat. The headrest can be a power headrest that is part of a power seat system, where the position of the headrest can be preset by a seat occupant with the other positions of the seat in a memory function. The system includes a seat occupant sensing system that senses the position of the seat occupant's head, eyes or other facial features to determine a desired position of the headrest. The system compares the actual position of the headrest to the desired position, and automatically adjusts the position of the headrest to the desired position. In one embodiment, an imaging system determines the position of the seat occupant's head. In another embodiment, the system determines the position of seat occupant's eyes based on the position of the driver side mirror.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates generally to a headrest positioning system for automatically positioning a vehicle seat headrest and, more particularly, to a headrest positioning system for automatically positioning a vehicle seat headrest by detecting the position of the head or facial feature of a seat occupant to determine a desired position of the headrest, and comparing the desired position of the headrest to a sensed position of the headrest.

2. Discussion of the Related Art

Most vehicle seats employ a headrest positioned behind the head of a seated occupant. Known vehicle seat headrests are adjustable relative to the seat back so that the seat occupant can manually position the headrest at the proper location. Typically the headrest is slidably positionable relative to the seat back by an actuating device that moves a headrest support into and out of the seat back. It is desirable to provide a system that automatically adjusts the headrest relative to a particular seat occupant without intervention from the occupant.

SUMMARY OF THE INVENTION

In accordance with the teachings of the present invention, a headrest positioning system is disclosed for automatically positioning a headrest of a vehicle seat. In one embodiment, the headrest is a power headrest that is part of a power seat system, where the position of the headrest can be preset by the seat occupant with other positions of the seat in a memory function. The positioning system includes a sensing system that senses the position of the seat occupant's head, eyes or other facial features to determine a desired position of the headrest. The system compares the actual position of the headrest to the desired position, and automatically adjusts the position of the headrest to the desired position. In one embodiment, an imaging system determines the position of the seat occupant's head. In another embodiment, the system determines the position of the seat occupant's eyes based on the position of the driver side mirror. The system can determine the position of the driver side mirror for both a blind zone side mirror setting method and a blind zone/glare elimination side mirror setting method. The automatic operation of the headrest positioning system can be manually over-ridden to allow the seat occupant to adjust the headrest to another position.

Additional advantages and features of the present invention will become apparent from the following description and appended claims taken in conjunction with the accompanying drawings.

DETAILED DESCRIPTION OF THE EMBODIMENTS

The following discussion of the embodiments of the invention directed to a system for automatically positioning a vehicle seat headrest is merely exemplary in nature, and is in no way intended to limit the invention or its applications or uses.

FIG. 1is a side view of a vehicle seat10for supporting a seat occupant12in a vehicle. The vehicle seat10includes a seat cushion14, a seat back16, a headrest18and a headrest support20. The headrest support20is mounted to a seat back support structure24positioned in the seat back16by a linear actuator26, including a sensor, and a rotational actuator28, including a sensor. The actuators26and28can be any actuator suitable for positioning the headrest18for the automatic headrest positionable system discussed below. The seat occupant12includes a head32and eyes34.

As will be discussed in detail below, the present invention proposes automatically positioning the headrest18relative to the seat occupant12based on the sensed position of a feature of the seat occupant12, such as the seat occupant's head32, eyes34, nose, etc., so it is in a desired position. In one embodiment, it is only the drivers headrest that: is automatically adjusted based on the position of the driver's feature. This automatic adjustment of the drivers headrest can serve as a headrest adjustment reminder for other occupants in the vehicle whose headrests are not automatically positioned.

To provide the calculations to determine the proper position of the headrest18based on the position of the seat occupant12, an axis40extending through the seat cushion16is defined from a bottom point42of the seat back16to a point44relative to the actuators26and28. Additionally, an axis46is defined between a reference point48at the top of the headrest18to the point44. The calculations are performed in an x-y-z reference frame relative to the seat10. Z is the distance from the seat occupant's eyes34to the point48in the z-direction and X is the distance from the seat occupant's eyes34to the point48in the x-direction. It is within the scope of the present invention that the distance from another feature of the seat occupant12to the reference point C can be used. For the analysis below, point42is A, point44is B, point48is C and the point at the eyes34is E.

From these variables the following constraint equations can be provided:
xc=xE+X(1)
yc=zE+Z(2)

According to one embodiment of the present invention, the headrest18is pivotable forward and backward by the rotational actuator28where the angle Ψ is adjustable. Additionally, the headrest18is adjustable up and down by the linear actuator26where the length (AB) of the axis40between the points42and44is adjustable. In this embodiment, the position (AB,Ψ) of the headrest18is determined from the following equations.

According to another embodiment of the present invention, the headrest18is pivotable forward and backward by the rotational actuator28where the angle Ψ is adjustable, and the length (BC) of the axis46is adjustable by the linear actuator26. For this embodiment, the following equations are used to determine the position (BC,Ψ) of the headrest18.

FIG. 2is a block diagram of a headrest positioning system60that automatically adjusts the position of a headrest62relative to a vehicle seat64consistent with the discussion above. The system60is used in combination with a position detection system66that provides a signal indicative of the position of a physical feature of the seat occupant12, such as his head, eyes, nose, etc. Many systems are known in the art that use imaging or vision technology for determining the position of a particular feature of a person within a vehicle for various purposes.

The signal of the position of the seat occupant's feature from the position detection system66is sent to a seat module controller68that controls the position of the seat cushion and seat back of the seat64through various motors and the like. Many different seat positioning systems are known in the art that are applicable for the system60. The position of the seat cushion and seat back can be preset in a memory so that the seat occupant can simply activate a switch that provides all of the positions of the seat64, including the headrest62. Signal lines for the motors in the seat64are provided by the seat module controller68to control the position of the seat, and sensor signals from positioning sensors in the seat64tell the seat module controller68the position of the seat parts. Power seat switches70can be used to separately adjust the several parts of the seat64if desired.

The signal from the position detection system66and the seat position signals from the seat module controller68are provided to a headrest system controller72. The headrest system controller72controls the position of the headrest62, either automatically or manually, consistent with the discussion herein. The headrest system controller72provides motor signals to the motors within the headrest62, representing the actuators26and28. Sensor signals from the headrest62indicating the position of the headrest62are sent to the headrest controller72so that it knows the position of the headrest62. The sensors used to identify the position of the headrest62can be any sensor suitable for this purpose, such as a potentiometer. A power headrest switch74is used to control the position of the headrest62by the seat occupant if desired. In one embodiment, the power switch74over-rides the automatic positioning of the headrest62.

FIG. 3is a block diagram of the headrest positioning system60used in combination with a power side mirror system80including a driver side mirror82. The position of the driver side mirror82is used to determine the position of the driver's eyes for the seat module controller68. In other words, the power side mirror system80provides a signal to the seat module controller68indicative of the position of the driver's eyes based on the position of the driver side mirror82. The vehicle operator uses an adjustment switch84to adjust the position of the driver side mirror82through a driver side mirror controller86. The driver side mirror controller86provides motor signals to the motors in the driver side mirror82, and receives sensor signals from sensors of the position of the driver side mirror82so that it knows the position of the mirror82. The driver can also use the adjustment switch84to control a passenger side mirror88through a passenger side mirror controller90in the same manner.

U.S. Pat. No. 6,840,637 titled Exterior Rearview Mirror System, assigned to the Assignee of this application and herein incorporated by reference, discloses an exterior rear view mirror system that automatically adjusts the position of the passenger side mirror in response to changes made by the vehicle operator to the drivers side mirror. The mirror system disclosed in the '637 patent can be used as the power side mirror system80in one embodiment.

FIG. 4is a flow chart diagram100showing one process for automatically controlling the position of the headrest18, according to an embodiment of the present invention. A seat occupant detection system102provides a signal of the position of the seat occupant to a box104that estimates the desired position of the headrest18. The detection system102can be the position detection system66, the power side mirror system80, or any other system suitable for the purposes described herein for identifying the position of the seat occupant's head. Additionally, the box104receives the seat position signals from a seat controller106, representing the seat controller68, that receives seat position signals from seat sensors108. The algorithm determines the desired position of the headrest18at the box104and then gets the detected position of the headrest18at box110from headrest position sensors112.

The algorithm then determines whether the current position of the headrest18is at the desired position of the headrest18for the seat occupant's head at decision diamond114. If the position of the headrest18is at the desired position, then the algorithm is through. However, if the position of the headrest18is not at the desired position at the decision diamond114, then the algorithm activates the headrest actuators26and28to adjust the position of the headrest18at box116. The seat occupant can then manually adjust the position of the headrest18using a power headrest switch118that is detected by the algorithm if he is not satisfied with the automatic position of the headrest18. The algorithm determines whether a manual adjustment to the headrest18has been made at decision diamond120, and if the seat occupant has manually adjusted the position of the headrest18, then the algorithm does not provide the automatic adjustment thereafter. However, if the seat occupant has not adjusted the position of the headrest18at the decision diamond120, then the algorithm returns back to getting the sensed position of the headrest18at the box110.

As discussed above, one embodiment of the present invention determines where to automatically position the headrest18based on the position of the driver side mirror, which provides the position of the driver's eyes. However, two techniques are known in the art for setting the position of the side mirrors of a vehicle. The first technique is referred to as a blind zone side mirror setting method where the vehicle operator sets the side mirrors of the vehicle so that the normal blind zones of the vehicle are not covered.

FIG. 5is a top view andFIG. 6is a side view of a vehicle126including a rear view mirror128, a driver side mirror130and a passenger side mirror132. Point E represents the position of the driver's eyes, and point S is the distance from the driver's eyes to the driver side mirror130in a forward direction. From these diagrams, the following equations are used to determine the position E for the system above that calculates the desired position of the headrest18for the blind zone side mirror setting method.

It is also known in the art to set the position of the side mirrors of a vehicle to help to eliminate the blind spots, referred to in the art as a blind zone/glare elimination (BGE) side mirror setting method. In this method, the vehicle operator moves his head to the far left to set the driver side mirror and the far right to set the passenger side mirror. This allows the side mirrors to be used to better see the vehicle blind spots when the driver is in the normal driving position, where the rearview mirror is used to view the remainder of the area behind the vehicle.

FIG. 7is a top view of a vehicle136andFIG. 8is a side view of the vehicle136showing the BGE side mirror setting method. The vehicle136includes a rearview mirror138, a driver side mirror140and a passenger side mirror142. The variables identified inFIGS. 7 and 8are used to calculate the desired position of the driver's eye E based on the following equations for the BGE side mirror setting method.

The question then remains, how does the automatic headrest positioning system of the invention know whether the vehicle operator has used the blind zone setting method or the BGE setting method to set the position of the side mirrors of the vehicle.FIG. 9is a graph with driver side mirror left-right angle on the horizontal axis and passenger side mirror left-right angle on the vertical axis. For a particular vehicle, graph line150represents the position of the driver side mirror and passenger side mirror if the blind zone setting method is used and graph line152represents the position of the driver side mirror and the passenger side mirror if the BGE setting method is used. Therefore, the control algorithm of the headrest positioning system of the invention would know which method the vehicle operator used to set the side mirrors based on their angle, where line154represents a threshold between the two side mirror setting methods.