Abstract: A seating state detection device includes an acquisition unit configured to acquire a detection signal group in a predetermined period that is output as a result of transmission and reception of waves by a radio wave sensor mounted on a vehicle, a signal extraction unit configured to extract specific-intensity signals in a predetermined reflection intensity range from the detection signal group, and a determination unit configured to determine whether an occupant in the vehicle is in a first riding state in which the occupant is directly seated on a seat or in a second riding state in which the occupant is seated in an infant auxiliary device, based on a distribution mode of the specific-intensity signals.

Abstract: A seating state detection device includes an acquisition unit configured to acquire a detection signal group in a predetermined period that is output as a result of transmission and reception of waves by a radio wave sensor mounted on a vehicle, a signal extraction unit configured to extract specific-intensity signals in a predetermined reflection intensity range from the detection signal group, and a determination unit configured to determine whether an occupant in the vehicle is in a first riding state in which the occupant is directly seated on a seat or in a second riding state in which the occupant is seated in an infant auxiliary device, based on a distribution mode of the specific-intensity signals.

Abstract: An occupant detection device includes: a radio wave sensor located above a seat surface of a seat that is disposed in a vehicle cabin of a vehicle, in a vertical direction of the vehicle, and including a transmission unit configured to transmit a transmission wave to the vehicle cabin and a reception unit configured to receive a reflected wave generated by the transmission wave being reflected by an occupant on the seat; a creation unit configured to create, based on the reflected wave, three-dimensional map information in the vehicle cabin in which a position of a reflection point of the reflected wave is represented by three-dimensional coordinates; and a calculation unit configured to calculate, based on the three-dimensional map information, backbone information that is information on a backbone of the occupant on the seat.