Control System Design And Safety Assessment For The Actuator Of Horizontal Tail

The extensive utilization of Electro-Mechanical Actuator(EMA) is the important feature of More-Electric/All-Electric aircraft systems, the EMA is the key actuator of flight control system, therefore the high-performance of the EMA is absolutely imperative. Because of the EMA's advantages such as simple mechanism, high power and adjustable-speed, the Brushless DC(BLDC) motor are widely applied in the EMA. The most important requirement of civil aircraft is safety. During the development of civil aircraft system, safety assessment and related analytical tools must be performed to characterize the validity of design.The EMA is an inherent nonlinear ? multivariable and strong-coupling system, therefore the conventional control strategy, such as the Classic PID cannot satisfy the requirement. In order to improve the dynamic response and general property of the EMA, the thesis proposes an EMA control system based on Active Disturbance Rejection Control Technique(ADRC), and researches on its control methods and system implementation. Numerical simulation results show that the proposed controller has strong robustness and adaptability. The designed controller not only satisfies the rapid and steady-state accuracy demands, but also effectively resists to the load change and external disturbance.This paper studies theory foundation of the ADRC,and analyzes the structure and principle of tracking differentiator, extended state observer, non-1inear state feedback. Additional attention is paid to not only the realization of the discrete algorithm for the active disturbance rejection control, but also the parameter tuning method. The result of the numerical simulation indicates that this method has strong adaptability and robustness.The most important requirement of civil aircraft design is the safety, system safety assessment is a systematic approach to show the compliance of the CCAR/FAR 25.1309. In order to carry out safety assessment on EMA, firstly, this paper briefly introduces the concept of System Safety Analysis and the role in the System Safety Analysis played by three procedures which include Functional Hazard Assessment(FHA), Preliminary System Safety Assessment(PSSA) and System Safety Assessment(SSA).Besides, the application of a few method in those processes is discussed, which includes Failure Modes and Effects Analysis(FMEA) and Fault Tree Analysis(FTA). Finally, focusing on the failure caused by the EMA mechanical jamming, the security assessment was conducted for the horizontal stabilizer to verify that the system design conforms to the intended targets and requirements.