Seat

1 . A seat in a vehicle, the seat comprising:

a seat surface member configured to support a waist and thighs of an occupant seated on the seat surface member, the occupant performing a steering operation of the vehicle;

a seat back configured to abut on a back of the occupant;

an actuator including:

an electric motor;

a reduction gear; and

a mechanism that transforms a rotational motion to a translational motion; and

an actuator control processor that:

transmits an actuation instruction to the actuator that changes a rigidity of a part of the seat back abutting on a vicinity of shoulder blades of the occupant via operation of the mechanism;

predicts whether the steering operation is performed; and

controls the actuator that increases the rigidity, via the mechanism, of a part of the seat back abutting on a vicinity of shoulder blades of the occupant before the steering operation is started when it is predicted that the steering operation is performed.

2 . The seat according to claim 1 , further comprising a sensor configured to recognize a lane shape in front of the vehicle and transmit a result to the actuator control processor,

wherein, based on the lane shape, the actuator control processor predicts whether the steering operation is performed.

3 . The seat according to claim 2 , wherein the seat back comprises an elastic body disposed to be opposed to the back of the occupant,

wherein the part of the seat back abutting on the vicinity of shoulder blades of the occupant includes a hard member harder than the elastic body and disposed to sandwich part of the elastic body between the hard member and an upper body of the occupant,

wherein the actuator, via the mechanism, drives the hard member in a direction of approaching or separating from the upper body of the occupant.

4 . The seat according to claim 2 , wherein the actuator control processor:

estimates a lateral acceleration acting on the vehicle after the steering operation is performed; and

increase, via the mechanism, an amount of the rigidity in proportion to an improvement in the lateral acceleration.

5 . The seat according to claim 1 , further comprising a turn signal operation detector that detects a turn signal operation by the occupant,

wherein, based on the turn signal operation being detected, the actuator control processor predicts that the steering operation is performed.

6 . The seat according to claim 5 , wherein the seat back comprises an elastic body disposed to be opposed to the back of the occupant,

wherein the part of the seat back abutting on the vicinity of shoulder blades of the occupant includes a hard member harder than the elastic body and disposed to sandwich part of the elastic body between the hard member and an upper body of the occupant,

wherein the actuator, via the mechanism, drives the hard member in a direction of approaching or separating from the upper body of the occupant.

7 . The seat according to claim 5 , wherein the actuator control processor:

estimates a lateral acceleration acting on the vehicle after the steering operation is performed; and

increase, via the mechanism, an amount of the rigidity in proportion to an improvement in the lateral acceleration.

8 . The seat according to claim 1 , wherein the seat back comprises an elastic body disposed to be opposed to the back of the occupant,

wherein the part of the seat back abutting on the vicinity of shoulder blades of the occupant includes a hard member harder than the elastic body and disposed to sandwich part of the elastic body between the hard member and an upper body of the occupant,

wherein the actuator, via the mechanism, drives the hard member in a direction of approaching or separating from the upper body of the occupant.

9 . The seat according to claim 1 , wherein the actuator control processor:

estimates a lateral acceleration acting on the vehicle after the steering operation is performed; and

increase, via the mechanism, an amount of the rigidity in proportion to an improvement in the lateral acceleration.

10 . The seat according to claim 1 , wherein the hard member is disposed at a height along a surface of the seat back from the seat surface member within a range of 440 mm to 470 mm to align with the vicinity of the shoulder blades of the occupant.

11 . The seat according to claim 1 , wherein the hard member comprises a left hard member and a right hard member, each disposed to align with a respective left shoulder blade and right shoulder blade of the occupant,

wherein the actuator comprises a left actuator drives the left hard member and a right actuator drives the right hard member, and

wherein the actuator control processor independently controls the left actuator and the right actuator to adjust the rigidity of the part of the seat back abutting on the vicinity of the respective left and right shoulder blades.

12 . The seat according to claim 11 , wherein, when it is predicted that the steering operation will be performed in a turning direction, the actuator control processor increases the rigidity of the part of the seat back abutting on the shoulder blade on an outer side of the turning direction more than the rigidity on an inner side of the turning direction.

13 . The seat according to claim 1 , further comprising a stereo camera device that captures images of a road in front of the vehicle,

wherein the actuator control processor predicts whether the steering operation will be performed based on a lane shape recognized from the images captured by the stereo camera device.

14 . The seat according to claim 1 , further comprising a navigation device that provides map data including a curvature radius of a curved road ahead of the vehicle,

wherein the actuator control processor predicts whether the steering operation will be performed based on the curvature radius.

15 . The seat according to claim 1 , wherein the actuator control processor:

estimates a curvature radius of a curved road ahead of the vehicle;

computes a predicted lateral acceleration based on the curvature radius and a vehicle speed; and

controls the actuator to increase the rigidity when the predicted lateral acceleration is equal to or greater than 2 m/s 2 .

16 . The seat according to claim 1 , wherein the actuator control processor moves the hard member to a normal position at a rear end of a movable range when no steering operation is predicted, thereby reducing the rigidity of the part of the seat back to a lower limit of an adjustable range.

17 . A seat, the seat comprising:

a seat surface member configured to support a waist and thighs of an occupant seated on the seat surface member, the occupant performing a steering operation of the vehicle;

a seat back configured to abut on a back of the occupant;

an actuator including:

an electric motor;

a reduction gear; and

a mechanism that transforms a rotational motion to a translational motion; and

circuitry that;

transmits an actuation instruction to the actuator that changes a rigidity of a part of the seat back abutting on a vicinity of shoulder blades of the occupant via operation of the mechanism;

predicts whether the steering operation is performed; and

controls the actuator to increase the rigidity, via the mechanism, of a part of the seat back abutting on a vicinity of shoulder blades of the occupant before the steering operation is started when it is predicted that the steering operation is performed.

18 . The seat according to claim 17 , wherein the hard member is disposed at a height along a surface of the seat back from the seat surface member within a range of 440 mm to 470 mm to align with the vicinity of the shoulder blades of the occupant.

19 . The seat according to claim 17 , wherein the hard member comprises a left hard member and a right hard member, each disposed to align with a respective left and right shoulder blade of the occupant,

wherein the actuator comprises a left actuator drives the left hard member and a right actuator drives the right hard member, and

wherein the circuitry independently controls the left actuator and the right actuator to adjust the rigidity of the part of the seat back abutting on the vicinity of the respective left and right shoulder blades.

20 . The seat according to claim 19 , wherein, when it is predicted that the steering operation will be performed in a turning direction, the circuitry increases the rigidity of the part of the seat back abutting on the shoulder blade on an outer side of the turning direction more than the rigidity on an inner side of the turning direction.