It is important to characterize the vibration present in such a vehicle, since the vibration is representative of stresses that lead to fatigue phenomena in various materials and that therefore have a direct influence on safety. Vibration may also degrade the performance of various items of equipment installed in the vehicle. In addition, vibration in the cabin of a helicopter determines the comfort of the passengers and of the pilot, and it goes without saying that pilot comfort is also an essential element for safety.
A system is thus known for continuously recording vibration within a helicopter, said system being known as a health usage and monitoring system (HUMS). The system records an alarm in a removable monitoring cartridge whenever the level of vibration exceeds a predetermined threshold at an identified frequency Ω, 2Ω, or BΩ, where Ω represents the speed of rotation of the rotor and B the number of blades mounted on the rotor.
It is also known to balance a rotor in order to reduce vibration in the cabin at each of the harmonics of the fundamental frequency Ω, with the exception of the harmonic B.
Nevertheless, at present, no means are provided for providing an indication of a level of vibration without being restricted to an identified frequency, i.e. no means are available that tend rather to take account of the overall behavior of the rotor.