论文部分内容阅读
Designing a controller for the docking maneuver in Probe-Drogue Refueling (PDR) is an important but challenging task, due to the complex system model and the high precision require-ment. In order to overcome the disadvantage of only feedback control, a feedforward control scheme known as Iterative Leing Control (ILC) is adopted in this paper. First, Additive State Decomposition (ASD) is used to address the tight coupling of input saturation, nonlinearity and the property of NonMinimum Phase (NMP) by separating these features into two subsystems (a primary system and a secondary system). After system decomposition, an adjoint-type ILC is applied to the Linear Time-Invariant (LTI) primary system with NMP to achieve entire output tra-jectory tracking, whereas state feedback is used to stabilize the secondary system with input satu-ration. The two controllers designed for the two subsystems can be combined to achieve the original control goal of the PDR system. Furthermore, to compensate for the receiver-independent uncertainties, a correction action is proposed by using the terminal docking error, which can lead to a smaller docking error at the docking moment. Simulation tests have been car-ried out to demonstrate the performance of the proposed control method, which has some advan-tages over the traditional derivative-type ILC and adjoint-type ILC in the docking control of PDR.