An excellent harmonic feedforward-sliding mode output feedback hybrid algorithm for helicopter active vibration control

Higher harmonic control algorithms in frequency domain are generally used for active vibration control of helicopter fuselage. However, these algorithms are inefficient to control transient vibration caused by rapid changing of helicopter flight conditions. Time domain feedback algorithms are efficient to control the transient vibration. In this paper, an excellent harmonic feedforward-sliding mode output feedback hybrid algorithm by combining frequency and time domain algorithms is presented to improve the effect and performance of active vibration control of helicopter fuselage, meanwhile to avoid the requirement of full state information of control system due to using the time domain algorithms. The convergence criterions of the harmonic feedforward algorithm and the hybrid algorithm are theoretically derived, respectively. The convergence speed of the hybrid algorithm is theoretically proved to be faster than that of the harmonic feedforward algorithm. Active vibration control simulation and experiment on a dynamically similar and geometrically scaled frame structure of a helicopter fuselage verify the proposed hybrid algorithm with excellent control effect and performance.