A pneumatic battering ram is disclosed. The outer side plate is fitted in a stationary die hole, and the inner side plate is fitted in the outer side plate hole of the outer side plate. The end point is considered to be a corner of a box, the threshold value is a function of the distance from the point to the nearest of the walls of the corner, and the threshold value goes to zero as the distance to the wall goes to zero. A fuel delivery system for a vehicle includes a fuel pump operable for supplying fuel to the engine, a fuel tank containing the fuel pump, and a controller having the state observer noted above.