A system includes a plurality of digital storage oscilloscopes in which each DSO requires a respective temporal portion of a signal under test according to a synchronized triggering signal and respective post-trigger count periods such that a plurality of acquisition records may be concatenated to produce a longer acquisition record. A tubular body is disclosed which includes in its side wall a plurality of longitudinal passages. The at least one lower arm is configured so as to define a second shear axis of predetermined orientation acting in series with the first axis, in such a manner that when the wheel carrier is subject to an external force acting in a substantially horizontal plane the displacement of the wheel carrier results from the combination of the rotations of the wheel carrier about the two shear axes. In the second mode, the seat portion is lowered to a level that is lower than the highest level. In addition, the airbag ECU includes a timer that measures an elapsed time after the voltage detected by the voltage detection section falls in a preset voltage range and a recording section that records the elapsed time measured by the timer on a memory when a failure of the other control units is detected.