Nonlinear analysis of oscillations in aero-hydraulic actuation system considering load effect

Hydraulic actuation control system demonstrates instability in several parameter regions. A nonlinear mathematical model of hydraulic rudder control system in airplane is established. Non-dimensional analysis is employed to analyze the regions of initial Hopf bifurcation which may lead to oscillations of hydraulic actuation system under the effect of load. Taking the system damping coefficient parameter as a reference, the load force of hydraulic actuators has great implications on the system stability. Numerical simulation using ODE solver indicates that stable impacting limit cycle exists at several particular parameters. The analysis in this paper can support the design and vibration control of the hydraulic rudder control system.