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Propeller synchrophasing control is an active method to reduce the noise and vibration of turboprop aircraft without additional weight and power. Phase control accuracy has a great influence on the noise reduction effect of synchrophasing. An integrated power/speed/synchrophasing control strategy is proposed to improve the control precision. Speed/phase control transformation logic based on a multi-blade phase plane is adopted which can take both the rapidity of speed response and phase control precision into account, but there exists switching oscillation during the mode transform process. In order to suppress the phase fluctuation due to exterior disturbance, a slave-slave control scheme is provided to take place of a master-slave scheme. Simulation results based on an integrated turboprop engine/propeller real-time non-linear model show that speed/phase integration logic can improve the response rapidity of both the speed and phase. The precision of the control system is verified to be in acceptable range.

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The UDE (uncertainty and disturbance estimator)-based control approach has received increasing attention due to its simplicity and effectiveness in rejecting input disturbances. Despite this fact, the inherent transient performance issues associated with a high-gain UDE are rarely considered. We first design a classic UDE-based robust controller for a linear system subject to three types of model uncertainties: exogenous disturbance, state-dependent uncertainty, and input-dependent uncertainty. We prove by the singular-perturbation theory that arbitrarily small steady-state tracking errors can be achieved by choosing an enough-high gain for the UDE. We then design a novel time-varying UDE (TV-UDE) to improve the transient performance. The key of the improved design is to use a differential equation with a time-varying parameter, instead of a transfer function, to describe the underlying filtering relationship. The formula for the integration by parts is introduced to derive an explicit computable expression of the TV-UDE. Interestingly, the TV-UDE is reduced to a classic UDE if the design parameter is fixed. In addition, two types of smooth and bounded functions are proposed to guide the change of UDE parameter from a large value to a smaller value (i.e., from a small gain to a higher one), to ensure that the UDE generates a smooth high-accuracy estimate. The advantages of the TV-UDE are demonstrated by simulation and experimental comparisons on a 2-DOF AERO attitude control platform. The transient performance issues (such as the peaking phenomenon and obvious oscillation) of high-gain UDE are effectively avoided.