Vehicle airbags for occupants in rear facing seats

1. A vehicle comprising:

an instrument panel;

a rear-facing seat adjacent the instrument panel and including a seatback and a headrest; and

an airbag including a lower portion and an upper portion,

wherein, when undeployed, the airbag is stored in the instrument panel,

wherein, when the airbag deploys, the lower portion presses onto a back of the seatback and the upper portion presses onto a back of the headrest;

wherein the airbag includes tethers between a front and a back of the upper portion, the tethers constrain a thickness of the upper portion to control head kinematics of an occupant during certain collisions; and

wherein the tethers include side tethers on each side of the upper portion, the side tethers constrain thicknesses of side sections to control lateral head kinematics of the occupant during a frontal oblique collision.

2. The vehicle of claim 1 , wherein, when the airbag deploys during a collision, the lower portion presses onto the back of the seatback to reduce acceleration of an upper body of an occupant and the upper portion presses onto the back of the headrest to reduce rotation of a head of the occupant.

3. The vehicle of claim 1 , wherein the airbag is configured to deploy onto a back of the rear-facing seat for at least one of a front collision and a frontal oblique collision.

4. The vehicle of claim 1 , wherein the airbag deploys onto a back of the rear-facing seat to deter the airbag from deploying onto an occupant.

5. The vehicle of claim 4 , wherein, by deploying onto the back of the rear-facing seat, the airbag is able to deploy earlier at an increased velocity to further restrain the occupant during a collision.

6. The vehicle of claim 1 , wherein the airbag includes sewn lines that extend between a front and a back of the airbag along a center section of the lower portion, the sewn lines constrain a thickness of the center section of the lower portion to reduce acceleration of an upper body of an occupant during a collision.

7. The vehicle of claim 1 , wherein the tethers include central tethers located within a center section the upper portion, the central tethers constrain a thickness of the center section of the upper portion to control the head kinematics of the occupant during certain front collisions.

8. The vehicle of claim 1 , wherein the airbag includes protrusions extending from each side of a front the upper portion, the protrusions extend beyond the headrest to control lateral head kinematics of an occupant during a frontal oblique collision.

9. The vehicle of claim 1 , further including a restraint control module that controls deployment of the airbag.

10. The vehicle of claim 9 , further including at least one of an inertial measurement unit, an accelerometer, and a pressure sensor to detect a collision, wherein the restraint control module deploys the airbag in response to detecting the collision.

11. An autonomous vehicle comprising:

a rear-facing seat for an occupant that includes a seatback and a headrest; and

an airbag including a lower portion and an upper portion, wherein, when the airbag deploys, the lower portion contacts a back of the seatback to reduce acceleration of an upper body of the occupant and the upper portion contacts a back of the headrest to control head kinematics of the occupant;

wherein the airbag includes protrusions extending from each side of a front of the upper portion, the protrusions extend beyond the headrest to control lateral head kinematics of the occupant during a frontal oblique collision.

12. The autonomous vehicle of claim 11 , further including a restraint control module that deploys the airbag for a front collision or a frontal oblique collision.

13. The autonomous vehicle of claim 11 , wherein when the airbag deploys, the lower portion presses onto the back of the seatback to reduce the acceleration of the upper body of the occupant and the upper portion presses onto the back of the headrest to control the head kinematics of the occupant.

14. The autonomous vehicle of claim 11 , wherein the airbag includes sewn lines that extend between a front and a back of the airbag along a center section of the lower portion, the sewn lines constrain a thickness of the center section to reduce the acceleration of the upper body of the occupant during a collision.

15. The autonomous vehicle of claim 11 , the airbag includes tethers between a front and a back of the upper portion, the tethers constrain a thickness of the upper portion to control the head kinematics of the occupant during certain collisions.

16. An airbag for a seat having a seatback and a headrest, the airbag comprising:

a front;

a back;

a lower portion to deploy onto the seatback and including sewn lines extending between the front and the back; and

an upper portion to deploy onto the headrest and including:

tethers extending between the front and the back; and

protrusions protruding from the front of the upper portion and extending beyond the headrest when deployed.