An article carrier for a motor vehicle having a cross bar with a pair of end supports at each end, where each end support can be simultaneously locked or unlocked by lifting an actuating member of either end support. A plant mechanically models at least a portion of the disk drive, receives a control command to which an unknown disturbance is added and generates a plant output. The transmitting member is arranged to be rotatable about the rotational center axis of the crankshaft and to transmit rotation to the crankshaft. The fiber is irradiated with broadband light, and the reflection is spectrally separated to produce separate spectra for all sensors.