Browsing by Author "Zhao, Zhiwen"
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Item Open Access Actuator fault tolerant control of variable cycle engine using sliding mode control scheme(MDPI, 2021-01-27) Yuan, Yuan; Zhang, Tianhong; Lin, Zhonglin; Zhao, Zhiwen; Zhang, XinglongThis paper presents a fault tolerant control (FTC) design for the actuator faults in a variable cycle engine (VCE). Ensured by the multiple variable geometries structure of VCE, the design is realized by distributing the control effort among the unfaulty actuators with the “functional redundancy” idea. The FTC design consists of two parts: the fault reconstruction part and the fault tolerant control part, which use a sliding mode observer (SMO) and a sliding mode control (SMC) scheme respectively. Considering the inaccuracy of the fault reconstruction result, the proposed design requires only inaccurate fault information. The stability of the closed-loop control system is proved and the existence condition for the proposed control law is analyzed. This work also reveals its relation to the sliding mode control allocation design and the adaptive SMC design. An application case is then studied for tolerating the loss of effectiveness fault of the nozzle area actuator. Results show that the FTC design is able to tolerate the fault and achieves the same control goal as in the fault-free situation. Finally, a hardware-in-the-loop test is carried out to verify the design in a real-time distributed control system, which demonstrates its use from the engineering perspective.Item Open Access An electro-pneumatic force tracking system using fuzzy logic based volume flow control(2019-10-22) Lin, Zhonglin; Wei, Qingyan; Ji, Runmin; Huang, Xianghua; Yuan, Yuan; Zhao, ZhiwenIn this paper, a fuzzy logic based volume flow control method is proposed to precisely control the force of a pneumatic actuator in an electro-pneumatic system including four on-off valves. The volume flow feature, which is the relationship between the duty cycle of the pulse width modulation (PWM) period, pressure difference, and volume flow of an on-off valve, is based on the experimental data measured by a high-precision volume flow meter. Through experimental data analysis, the maximum and minimum duty cycles are acquired. A new volume flow control method is introduced for the pneumatic system. In this method, the raw measured data are innovatively processed by a segmented, polynomial fitting method, and a newly designed procedure for calculating the duty cycle is adopted. This procedure makes it possible to combine the original data with fuzzy logic control (FLC). Additionally, the method allows us to accurately control the minimum and maximum opening pulse width of the valve. Several experiments are performed based on the experimental data, instead of the traditional theoretical models. Only 0.141 N (1.41%) overshoot and 0.03 N (0.03%) steady-state error are observed in the step response experiment, and 0.123 N average error is found while tracking the sine wave reference.Item Open Access A mimicking technique of back pressure in the hardware-in-the-loop simulation of a fuel control unit(Sage, 2019-09-17) Yuan, Yuan; Zhao, Zhiwen; Zhang, TianhongIn the hardware-in-the-loop (HIL) simulation of the fuel control unit (FCU) for aero-engines, the back pressure has a great impact on the metered fuel, thus influencing the confidence of the simulation. During the practical working process of an aero-engine, the back pressure of the FCU is influenced by the combined effect of the pressure of the combustion chamber, the resistance of the spray nozzles, and the resistance of the distribution valve. There is a need to study the the mimicking technique of FCU back pressure. This paper models the fuel system of an aero-engine so as to reveal the impact of FCU back pressure on the metered fuel and come up with a scheme to calculate the equivalent FCU back pressure. After analyzing the requirements for mimicking the pressure, an automatic regulating facility is designed to adjust the FCU back pressure in real time. Finally, experiments are carried out to verify its performance. Results show that the mimicking technique of back pressure is well suited for application in HIL simulation. It is able to increase the confidence of the simulation and provide guidance to the implementation of mimicking the FCU back pressure.