Limit strategy for multi-input multi-output random vibration control

Abstract

Multi-input multi-output random vibration control combined with limit channels is a commonly used experiment scheme in dynamic environmental testing. This paper proposes a limit control strategy for multi-shaker random vibration tests. Compared to the traditional limit control method, the presented work can alleviate the undertesting phenomenon. The fundamental principles and difficulties in limit control are first formulated and analyzed. It is found that limit auto spectral density can be modified by simultaneously manipulating the control auto and cross spectral density. After that, the proposed limit control strategy is elaborated with a matrix presentation. An intermediate spectral matrix is defined and then it is used to obtain a redefined reference spectral matrix. The multi-input drive signals are generated and updated by the control and limit spectral correction algorithms. A two-input two-output numerical simulation with three limit channels and a tri-axial random vibration experiment are provided. The results from the simulation and experiment show the feasibility and validity of the proposed method.