scholarly journals Novel Prescribed Performance Control Scheme for Flexible Hypersonic Flight Vehicles with Nonaffine Dynamics and Neural Approximation

2021 ◽  
Vol 2021 ◽  
pp. 1-14
Author(s):  
Yong Liu ◽  
Gang Li ◽  
Yuchen Li ◽  
Yahui Wu

This study develops a novel neural-approximation-based prescribed performance controller for flexible hypersonic flight vehicles (HFVs). Firstly, a new prescribed performance mechanism is exploited, which develops new performance functions guaranteeing velocity and altitude tracking errors with small overshoots. Compared with the existing prescribed performance mechanism, it has better preselected transient and steady-state performance. Then, the nonaffine model of HFV is decomposed into a velocity subsystem and an altitude subsystem. A prescribed performance-based proportional-integral controller is designed in the velocity subsystem. In the altitude subsystem, the model is expressed as a nonaffine pure feedback form, and control inputs are derived from neural approximations. In order to reduce the amount of computation, only one neural network approximator is used to approximate the subsystem uncertainties, and an advanced regulation algorithm is applied to the devise adaptive law for neural estimation. At the same time, the complex design process of back-stepping can be avoided. Finally, numerical simulation results are presented to verify the efficiency of the design.

2019 ◽  
Vol 2019 ◽  
pp. 1-11 ◽  
Author(s):  
Siyuan Zhao ◽  
Xiaobing Li ◽  
Xiangwei Bu ◽  
Dongyang Zhang

This paper proposes a novel prescribed performance tracking control for a hypersonic flight vehicle (HFV) with model uncertainties. Firstly, a HFV longitudinal motion model is decomposed into a velocity subsystem and an altitude subsystem. Meanwhile, considering the uncertainties of the model, the velocity subsystem and altitude subsystem are directly expressed as the forms with unknown nonaffine functions. Secondly, a novel performance function without initial error is proposed for limiting the tracking error into a prescribed range. Then, for the altitude subsystem, the control objective is changed by model transformation and the prescribed performance backstepping controller is designed. For the velocity subsystem, a prescribed performance proportional-integral controller is proposed which has better engineering practicability. The designed controller is not only simple in form but also has few calculating parameters. Finally, the simulation results show that the proposed controller has good practicability.


2021 ◽  
Vol 2021 ◽  
pp. 1-16
Author(s):  
Junbao Wei ◽  
Haiyan Li ◽  
Ming Guo ◽  
Jing Li ◽  
Huang Huang

An antisaturation backstepping control scheme based on constrained command filter for hypersonic flight vehicle (HFV) is proposed with the consideration of angle of attack (AOA) constraint and actuator constraints of amplitude and rate. Firstly, the HFV system model is divided into velocity subsystem and height subsystem. Secondly, to handle AOA constraint, a constrained command filter is constructed to limit the amplitude of the AOA command and retain its differentiability. And the constraint range is set in advance via a prescribed performance method to guarantee that the tracking error of the AOA meets the constraint conditions and transient and steady performance. Thirdly, the proposed constrained command filter is combined with the auxiliary system for actuator constraints, which ensures that the control input meets the limited requirements of amplitude and rate, and the system is stable. In addition, the tracking errors of the system are proved to be ultimately uniformly bounded based on the Lyapunov stability theory. Finally, the effectiveness of the proposed method is verified by simulation.


2017 ◽  
Vol 40 (4) ◽  
pp. 1362-1374 ◽  
Author(s):  
Shen Zhang ◽  
Qing Wang ◽  
Chaoyang Dong

In this paper, the nonlinear adaptive velocity and altitude tracking controller is developed for the longitudinal dynamics of generic air-breathing hypersonic flight vehicles. The proposed control scheme is designed using dynamic surface control method. The velocity and altitude subsystems are transformed into the linearly parameterized form for the convenience of adaptive law design. Both of the thrust and actuator constraints are explicitly considered. For thrust constraint, two cases are analyzed when the fuel-to-air ratio reaches its max and min values. A novel adaptive law is proposed to avoid over or less estimation in thrust saturation occasion. For actuator constraint, a magnitude and rate limiting filter is incorporated. The filter guarantees that the control signal is applicable for the actuator. It is shown that with the application of the proposed control scheme, all signals of the closed-loop system are uniformly ultimately bounded and the velocity and altitude tracking errors converge to a residual set which is arbitrarily small. Simulation results are demonstrated to show the effectiveness and superiority of the proposed control scheme.


2017 ◽  
Vol 14 (1) ◽  
pp. 172988141668270 ◽  
Author(s):  
Zhonghua Wu ◽  
Jingchao Lu ◽  
Jingping Shi ◽  
Qing Zhou ◽  
Xiaobo Qu

A robust adaptive neural control scheme based on a back-stepping technique is developed for the longitudinal dynamics of a flexible hypersonic flight vehicle, which is able to ensure the state tracking error being confined in the prescribed bounds, in spite of the existing model uncertainties and actuator constraints. Minimal learning parameter technique–based neural networks are used to estimate the model uncertainties; thus, the amount of online updated parameters is largely lessened, and the prior information of the aerodynamic parameters is dispensable. With the utilization of an assistant compensation system, the problem of actuator constraint is overcome. By combining the prescribed performance function and sliding mode differentiator into the neural back-stepping control design procedure, a composite state tracking error constrained adaptive neural control approach is presented, and a new type of adaptive law is constructed. As compared with other adaptive neural control designs for hypersonic flight vehicle, the proposed composite control scheme exhibits not only low-computation property but also strong robustness. Finally, two comparative simulations are performed to demonstrate the robustness of this neural prescribed performance controller.


Machines ◽  
2022 ◽  
Vol 10 (1) ◽  
pp. 55
Author(s):  
Qiang Gao ◽  
Yong Zhu ◽  
Jinhua Liu

A fuel metering valve actuated by two binary-coded digital valve arrays (BDVAs) is proposed to improve the reliability of conventional fuel metering valves piloted by a servo valve. The design concept of this configuration is obtained from the structural characteristics of the dual nozzle-flapper and the flow regulation method of the digital hydraulic technology. The structure and working principle of the fuel metering valve are presented. Then, a mathematical model of the entire valve is developed for dynamic analysis. Subsequently, the mechanism of the transient flow uncertainty of the BDVA is revealed through simulation to determine the fluctuation in the velocity of the fuel metering valve. Furthermore, step response indicates that the delay time of the fuel metering valve is within 4.1 ms. Finally, to improve the position tracking accuracy of the fuel metering valve, a velocity feedforward proportional-integral controller with pulse code modulation is proposed. A series of comparative analyses indicate that compared with those of the velocity feedforward controller, the average and standard deviation of the position error for the proposed controller are reduced by 78 and 72.7%, respectively. The results prove the feasibility of the proposed valve and the effectiveness of the proposed control strategy.


2018 ◽  
Vol 41 (4) ◽  
pp. 975-989 ◽  
Author(s):  
Ziquan Yu ◽  
Youmin Zhang ◽  
Yaohong Qu

In this paper, a prescribed performance-based distributed neural adaptive fault-tolerant cooperative control (FTCC) scheme is proposed for multiple unmanned aerial vehicles (multi-UAVs). A distributed sliding-mode observer (SMO) technique is first utilized to estimate the leader UAV’s reference. Then, by transforming the tracking errors of follower UAVs with respect to the estimated references into a new set, a distributed neural adaptive FTCC protocol is developed based on the combination of dynamic surface control (DSC) and minimal learning parameters of neural network (MLPNN). Moreover, auxiliary dynamic systems are exploited to deal with input saturation. Furthermore, the proposed control scheme can guarantee that all signals of the closed-loop system are bounded, and tracking errors of follower UAVs with respect to the estimated references are confined within the prescribed bounds. Finally, comparative simulation results are presented to illustrate the effectiveness of the proposed distributed neural adaptive FTCC scheme.


Author(s):  
Hao An ◽  
Qianqian Wu

This paper deals with the anti-windup control problem for a class of feedback linearizable systems subject to external disturbances and constrained actuators. The original system is approximately feedback linearized into a tractable form with additive mismatched disturbances. A baseline disturbance suppression control is built on the combination of a disturbance observer and a compensation law. Moreover, this baseline control is strengthened by two anti-windup mechanisms to accommodate the possible input saturation, leading to the anti-windup disturbance suppression control. The resulting control schemes guarantee output tracking errors to be bounded in the presence of input saturation, while the zero steady-state tracking is finally achieved due to the recovery property. The proposed methods are applied to the longitudinal tracking control of hypersonic flight vehicles to highlight their efficiency and superiority.


2013 ◽  
Vol 717 ◽  
pp. 541-545
Author(s):  
Young Sup Lee

This paper presents the effect of an integral feedback controller for minimizing the pointing error at the tip of a very flexible and slender cantilever beam to follow a command signal. A piezoeletric PZT actuator patch isbonded on near the clamped end of the cantilever beam. Also it is considered that a position sensor is located near the tip of the beam but it is not attached on the beam. The beam is designed to be lightly damped and its step response withoutcontrol is quite long. But because of the non-collocation of the sensor and actuator, the plant response is non-minimum phase. After an intensive computer simulation, it is noted that the integral controller can reduce the settling time with proper stability and control gains. Also an analysis and comparison of the integral controller with a proportional-integral controller for the pointing error minimization of the very flexible and slender beam is described in detail.


2021 ◽  
Author(s):  
Zehong Dong ◽  
Yinghui Li ◽  
Maolong Lv ◽  
Ju Park ◽  
Dingshan Sun

Abstract This article proposes a new fixed-time fuzzy adaptive fault-tolerant control methodology for the longitudinal dynamics of hypersonic flight vehicles (HFVs) in the presence of actuator faults, uncertain dynamics and external disturbances. In contrast with the conventional fixed-time control schemes that typically contain the fractional powers of errors in their designs, this work develops a low-complexity control structure in the sense of removing the dependence on the need of above-mentioned fractional power terms by means of prescribed performance control (PPC) method. Different from the most existing PPC approaches where the initial conditions of tracking errors are required to be known, the newly proposed prescribed performance function (PPF) can relax such restrictions through choosing properly small initial values of PPF. Fuzzy logic systems (FLSs) are employed to handle unknown dynamics and minimal learning parameter (MLP) technique is incorporated into the design for the purpose of alleviating computation burden. Closed-loop stability is rigorously proved via Lyapunov stability theory and simulation results are eventually given to validate the effectiveness of the proposed control strategy.


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