The aerospace electro-hydraulic servo simulator is used to simulate the air load received during flight, and is used for the performance test and acceptance test of aerospace servo actuators on the ground. The force loading accuracy of the load simulator is an important assessment index. Because the loading system and the actuator system to be tested are coupled together, the free displacement of the system to be tested during loading will bring huge disturbance to the loading system, thus how to suppress external interference has always been a hot issue in the control field. This paper addresses this issue under the influence of nonlinear friction and uncertain external disturbance. First, the exact mathematical model of the system is derived, and the characteristics of the system are described by the state equations. Second, in order to obtain the relevant parameters in the controller, the system parameters are identified. Third, the parameter adaptive sliding mode force control based on the reaching law is proposed, and the performance of the control algorithm is analyzed theoretically. Finally, the new control method is applied in the aerospace electro-hydraulic servo simulator, and the results show that the new control algorithm can suppress the external interference by 95% or more, and the control accuracy is more than 97%, which fully demonstrates the effectiveness of the control method.

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Polarization beam splitter is an important part of integrated optical system to overcome the strong polarization dependence of silicon nanodevices, and has broad application prospects in optical fiber communication and polarization imaging. In this paper, a polarization beam splitter of metalens based on the fiber end face is designed. Through the planar light field control ability of metalens and the coordinated regulation of the geometric phase and propagation phase, the device adjusts the medium duty cycle in the meta-unit and the rotation angle of the nanoantenna to realize the polarization beam splitting and focusing simultaneously. In order to simplify the manufacturing process and achieve high focusing efficiency even further, Si with high transmittance in the near infrared band is selected as the nanoantenna, and SiO2 is used as the substrate. Since the substrate used the same material with fiber cladding, compared with the traditional polarization beam splitter, the structure can directly etch the nanofins periodically on the fiber end face, which is convenient for optical system integration. Theoretical design and numerical simulation results show that any polarized light in fiber cladding can realize polarization focusing through fiber end face.

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In order to obtain high specific power, high specific capacity and highly reliable power supply, a combined power supply system is often used. As one of the main loads to the combined power supply system, the servo system can adjust the trajectory and attitude of the aerospace vehicles in real-time. However, a sudden change of the load to the servo system can have adverse effects on the DC bus voltage output, which will reduce the performance of the electrical equipment on the aerospace vehicles. Firstly, this paper theoretically deduces and analyzes the influence of servo loading conditions on the DC bus voltage of aerospace combined power supply. Secondly, in the field of aerospace combined power system, the mechanism of regulating DC bus voltage by combining bidirectional DC-DC converter and ultracapacitor is proposed, and its effectiveness and enforceability are verified by simulation and experiment. Finally, aiming at the strong nonlinear and time-varying characteristics of bidirectional DC-DC converter, a fuzzy predictive control algorithm which can effectively adjust the DC bus voltage is proposed, and a good regulation control effect is achieved.INDEX TERMS Aerospace combined power supply system, bidirectional DC-DC converter, DC bus voltage stabilization technology, fuzzy predictive control, Kalman filtering.