Vibration reduction in aerospace structures via an optimized modified positive velocity feedback control

In this paper, an optimized positive feedback based control approach is developed for unwanted resonant vibration attenuation of flexible lightweight aerospace structures. A modified form of the positive velocity feedback control (MPVF) is implemented, where the resonant compensator of each mode is enhanced with a parallel lossy integrator. For multi-mode control purpose and to control n-modes, n sets of parallel compensators are required. A focus of this paper is on development of effective gain optimization methods in order to improve the multi-mode suppression performance of the vibration controller. The optimization problem is addressed via the M-norm optimization method and the Linear Quadratic Regulator (LQR). A flexible clamped-free beam is considered as a sample aerospace structure, and the controller verification is performed experimentally. Results show that vibration velocity is well reduced, which is important in preventing fatigue failures in aerospace structures. The LQR-optimized MPVF provides a compensated result between vibration amplitude reduction and the consumed control power. The M-norm approach, on the other hand, aims to directly suppress each mode based on the assigned weighting coefficients. Since an M-norm-optimized MPVF controller focuses on modes with higher amplitudes of velocity, it provides a higher level of vibration suppression than LQR-optimized method.