Side collision detection system, occupant restraint system and vehicle

A side collision detection system for detecting a side collision to a vehicle, said system comprising:

• a first acceleration sensor provided on a beam of a door on one side of the vehicle, for detecting acceleration in a direction orthogonal to the advancing direction of the vehicle;
• a first collision determiner for detecting velocity in the direction orthogonal to the advancing direction of the vehicle based on output from the first acceleration sensor, and for determining whether or not the side collision has occurred based on the detected velocity;
• a second collision determiner for detecting an amount of change in displacement of the first acceleration sensor and an extent of change with time of the displacement of the first acceleration sensor based on output from the first acceleration sensor, and for determining whether or not the side collision has occurred based on the amount of change and the extent of change with time;
• a detector for detecting the side collision based on at least one out of the determination result of the first collision determiner and the determination result of the second collision determiner;
• and
• a velocity sensor for sensing a velocity of the vehicle;
• wherein the detector detects the side collision based on the determination result of the first collision determiner when the velocity of the vehicle is equal to or smaller than a threshold value.