Abstract: A vehicle collision detection system that includes: a controller that actuates an occupant restraint device in a case in which a collision between a vehicle and an object has been predicted by a collision prediction section, a collision mode has been determined to be an underride mode by a determination section, the object has been determined to be another vehicle by the determination section, and an acceleration detected by a first acceleration sensor is at or above an underride-mode-actuation determination threshold that is lower than a normal-actuation determination threshold for the occupant restraint device.

Abstract: A vehicle airbag device comprises an airbag that receives gas supplied from an inflator and that is adapted to be inflated and deployed in front of an upper body and above thighs of an occupant seated in a vehicle seat. The airbag includes, in the event that the gas has been supplied inside the airbag and the airbag inflates and deploys, an inflation section having an endless annular shape as viewed along a vehicle width direction, and a hollow section formed in a central portion of the inflation section. The hollow section is in communication with an exterior of the airbag, and air at the exterior flows into the hollow section during inflation and deployment.