A CUSUM test with sliding reference for ground resonance monitoring

Abstract

Ground resonance is potentially destructive oscillations that may develop on helicopters rotors when the aircraft is on or near the ground. Therefore, this unstable phenomenon has to be detected before it occurs in order to be avoided by the pilot. To predict the zones of instability, works have generally relayed on off-line modal analysis of the helicopter model. Unfortunately, this off-line analysis is not sufficiently reliable. The subspace-based cumulative sum CUSUM test, able of on-line monitoring, is a good alternative which permits - at once- to avoid the system identification for each flight point and to have more robust detection, with reduced costs. In this paper, we describe an alternative test- with a moving reference this time- in order to kill wrong alarms or premature responses that are observed for fixed-reference tests. Numerical results reported herein are driven from simulation data.