LQR-based Ground Resonance Suppression of Helicopter with Adaptive Landing Gear

Ground resonance (GR) is a potentially destructive mechanical instability involving the coupling of the regressive rotor mode to the fuselage motion. Vibration can be disastrous if measures are not taken in time to mitigate vibrations. This paper presents a study on the use of adaptive landing gear to eliminate GR in helicopters. A GR model considering adaptive landing gear is established, and the dynamic characteristics of the system are analyzed. In this paper, the Linear Quadratic Regulator (LQR) controller is applied to suppress the GR. The setting of the weighting matrix coefficients directly determines the effect of the control system. Therefore, a design method of LQR weighting matrix based on multi-objective genetic algorithm is proposed, which enables the control system to meet multiple performance indicators concurrently. Numerical simulations of GR suppression were performed for the rotor speed range where GR is most likely to occur. The results show that even if the rotor system is not equipped with any dampers, the suppression of helicopter GR can be achieved by using the control strategy proposed in this paper to control the adaptive landing gear. Therefore, the application of adaptive leg landing gear to helicopters can provide some ideas to eliminate GR.