Abstract: A seat includes a seat surface member, a seat back, a rigidity changer, a steering operation prediction unit, and a rigidity change controller. On the seat surface member, a waist and thighs of an occupant who is to perform steering operation on a vehicle are to be placed. The seat back is configured to abut on a back of the occupant. A rigidity changer is configured to change rigidity of a part of the seat back abutting on the vicinity of shoulder blades of the occupant. A steering operation prediction unit is configured to predict whether the steering operation is performed. A rigidity change controller is configured to control the rigidity changer to enhance the rigidity before the steering operation is started when it is predicted that the steering operation is performed.

Abstract: A shoulder blade position estimation apparatus for a vehicle is provided in a seat on which an occupant operating a steering wheel of the vehicle is seated, and configured to estimate positions of shoulder blades of the occupant. The shoulder blade position estimation apparatus includes a surface pressure sensor and a shoulder blade position estimation unit. The seat includes a seat surface member on which thighs and a waist of the occupant are placed, and a seat back disposed in rear of an upper body of the occupant. The surface pressure sensor detects a distribution of surface pressures that the seat back receives from the upper body of the occupant. When the occupant turns the steering wheel by a predetermined angle, the shoulder blade position estimation unit estimates that the shoulder blades are present near a region where the surface pressures on left and right sides change in opposite directions.

Abstract: A seat having a seat surface and a backrest includes a support member, a support-member driving unit, a specific-region position estimator, and a controller. The support member is provided in the backrest. The support member is configured to support a predetermined region of a body of a sitter to be seated on the seat and is movable in a vertical direction. The support-member driving unit is configured to drive the support member in the vertical direction relative to the backrest. The specific-region position estimator is configured to estimate a position of a specific region of the sitter that is defined in advance. The controller is configured to control the support-member driving unit such that the support member supports the specific region in accordance with the position of the specific region estimated by the specific-region position estimator.