Frame-based bladder apparatus for seat occupant weight estimation

The apparatus has a fluid filled bladder (26) sandwiched between two rigid plates (22, 24) and held between a seat frame (12) and floor brackets (16, 18) by a set of fasteners (30). A spring (32) preloads the bladder, such that deviations of a bladder fluid pressure from a preload pressure indicates a vehicle occupants weight. The plate (22) spans an open space between the floor brackets.