Fu Yongling

Architecture Optimization of More Electric Aircraft Actuation System

The optional types of power source and actuator in the aircraft are more and more diverse due to fast development in more electric technology, which makes the combinations of different power sources and actuators become extremely complex in the architecture optimization process of airborne actuation system. The traditional “trial and error” method cannot satisfy the design demands. In this paper, firstly, the composition of more electric aircraft (MEA) flight control actuation system (FCAS) is introduced, and the possible architecture quantity is calculated. Secondly, the evaluation criteria of FCAS architecture with respect to safe reliability, weight and efficiency are proposed, and the evaluation criteria values are calculated in the case that each control surface adopts the same actuator configuration. Finally, the optimization results of MEA FCAS architecture are obtained by applying genetic algorithm (GA). Compared to the traditional actuation system architecture, which only adopts servo valve controlled hydraulic actuators, the weight of the optimized more electric actuation system architecture can be reduced by 6%, and the efficiency can be improved by 30% based on the safe reliability requirements.

Research on Dual-Variable Integrated Electro-Hydrostatic Actuator

Abstract The integrated electro-hydrostatic actuator (EHA) with variable displacement and variable rotation speed is researched. In the system, the output of the actuator is changed by controlling the rotation speed of the brushless DC servomotor and the displacement of the servopump. The mathematical model described in state space model is created. The system characteristics are studied based on the point of multiplicative dual variable. And the basic method of control of the system is presented.

Design and Application of Discrete Sliding Mode Control with RBF Network-based Switching Law

Abstract This article proposes a novel approach combining exponential-reaching-law-based equivalent control law with radial basis function (RBF) network-based switching law to strengthen the sliding mode control (SMC) tracking capacity for systems with uncertainties and disturbances. First, SMC discrete equivalent control law is designed on the basis of the nominal model of the system and the adaptive exponential reaching law, and subsequently, stability of the algorithm is analyzed. Second, RBF network is used to form the switching law in a direct and online manner with sliding-mode-related inputs and by approximating evaluation function; and the method to adjust its parameters is devised. Finally, comparable experiments are carried out to verify the application of the proposed approach to an inner-axis driven by a direct current (DC) torque motor through extra-low speed servo for a high precision flight simulator, and the axis works under deteriorating conditions such as periodically fluctuating torques of motor, nonlinear friction, and time-varying model parameters. The results show that the combined SMC can effectively improve the servo performance, for instance, to a stable 0.000 08 (°)/s speed response, the tracking error would be within 0.000 08° in 98% of operating times. Moreover, the hybrid nature of the approach imparts the RBF network the features of removing offline training and ease to set initial parameters.

Research of the servo pump's electrically driven variable displacement mechanism

In this paper, an electrically driven variable displacement servo pump was designed to meet the requirement of dual-variable control in integrated electro-hydrostatic-actuator. The driving force of variable displacement mechanism of the servo pump was analyzed, and the mathematical model was created. A DC servo motor was selected as the executive unit of the variable displacement mechanism, the structure of the mechanism that drives the swashplate and the digital controller using digital signal processor (DSP) was designed.

Research on the controller of the digital cabin pressure regulating system based on FIMF

Based on the cabin pressure regulating system characters of the nonlinear, larger inertia and time varying parameter, the arithmetic of fuzzy immune feedback (FIMF) was proposed to adjust PID control parameters real time and increase response and control capability of pressure loop, and using immune algorithm adjusting pressure loop control parameters real time which has optimizing performance and using fuzzy algorithm as operator function. The simulation results show that cabin pressure and pressure change rate satisfy the rule of environment control system, and the effectiveness of the new control strategy proposed in this paper was proved.

The finite element model of transient temperature field of Electro-Hydraulic Pump

Aim. The full paper begins with a review on structure and main shortcoming of existing hydraulic pump, resulting in, in our opinion, the conclusion that it is absolutely essential to study on the Electro-Hydraulic Pump(EHP), a highly integration of electric motor and hydraulic pump. We now present a model how to get temperature field of our design plunger EHP that we believe that it can much better develop the EHP. In the full paper, we explain our method in some detail; in this abstract, we just add some pertinent remarks to naming the topics, such as motor thermal model, the fluid model and the heat conduction model. We discuss the temperature distribution under the condition of relationship among the oil film thickness, overall efficiency, leakage and cooling capacity. Finally we perform simulations in ANSYS. The simulation results, shown in the full paper, show preliminarily that our method for the temperature field is efficient to design the EHP.

Research on Valve and Pump Combined Control of Digital Actuator

This paper describes a new two-stage screw internal feedback digital actuator. It can be driven directly by digital pulse signal output of computer. The internal mechanical position feedback consisting of screw rod and valve spool with thread supplants the traditional position feedback consisting of position sensor and servo valve. The model of digital actuator is established in AMESim simulation environment. The research about valve and pump combined control is carried out based on this model. The part of valve control introduces a compensator to eliminate the error caused by load effect on position servo system. The other part of pump control achieves the purpose of energy-saving through system power matching control. Simulation results show that valve and pump combined control of digital actuator maintains dynamic performance and reduces energy consumption. This method effectively enhances efficiency of the system.Copyright

Life-Stress Model for Accelerated Life Test of Cylinders

Main stress types that affect the service life of cylinder were obtained through analysis of cylinder failure mechanism, including environmental temperature for cylinder operation, actuation velocity, positive pressure of load and gas pressure, a life-stress model for cylinder was built based on tribology theory, and the physical measurement unit for each variable was nailed down, data statistics, evaluation and transformation concerning accelerated life test were performed based on statistical theories that are related to the model, and cylinder reliability indices under normal stress conditions were reproduced accurately with temperature and velocity being used as the reliability information of accelerated stress to transform results.

Tri-stress accelerated life test for cylinders

A life-stress model for cylinders was built based on wear fault mechanism, and the test scheme was optimized using temperature, pressure and velocity as acceleration stresses. An accelerated life test for cylinders was designed and implemented. Life eigenvalues at different stress levels were acquired and analyzed. Undetermined parameters of acceleration model were estimated, and life indices under normal stress condition were extrapolated and compared with those from normal stress test. The feasibility of the optimization scheme and the correctness of the acceleration model were verified. Compared with twin-stress accelerated life test for cylinders, the test period was further shortened