Flight Control Law Using Nonlinear Dynamic Inversion Combined With Quantitative Feedback Theory

1998 ◽  
Vol 120 (2) ◽  
pp. 208-215 ◽  
Author(s):  
S. A. Snell ◽  
P. W. Stout
Keyword(s):  
Flight Control ◽  
High Performance ◽  
Large Angle ◽  
Dynamic Inversion ◽  
Control Law ◽  
Pitching Moment ◽  
Quantitative Feedback Theory ◽  
Control Laws ◽  
Nonlinear Version ◽  
Plant Uncertainty

A method of designing control laws for uncertain nonlinear systems is presented. Dynamic inversion is used to partially linearize the dynamics and then a nonlinear version of quantitative feedback theory (QFT) is applied to the resulting system which assures robustness to plant uncertainty. The design yields good performance with low bandwidth. An application to the design of flight control laws for a high performance aircraft is presented. The control laws demonstrate good performance by accurately following large angle of attack commands at flight speeds ranging from 53 to 150 m/s. Robustness is verified by including ±20 percent variations in pitching moment derivatives. The reduced bandwidth compared to a fixed-gain, linear design, leads to greatly reduced actuator transients, which should give improved reliability and longer life for the actuators and associated structure.

Supersonic transport aircraft longitudinal flight control law design

2004 ◽  
Vol 108 (1084) ◽  
pp. 319-329
Author(s):  
A. J. Steer
Keyword(s):  
Flight Control ◽  
Dynamic Inversion ◽  
Control Law ◽  
Transport Aircraft ◽  
Handling Qualities ◽  
Supersonic Transport ◽  
Linear Dynamic ◽  
Non Linear ◽  
Quality Design ◽  
Handling Quality

Abstract Modern civil transport aircraft utilise increasingly complex command and stability augmentation systems to restore stability, optimise aerodynamic performance and provide the pilot with the optimum handling qualities. Provided it has sufficient control power a second generation fly-by-wire supersonic transport aircraft should be capable of exhibiting similarly desirable low-speed handling qualities. However, successful flight control law design requires identification of the ideal command response type for a particular phase of flight, a set of valid handling quality design criteria and piloted simulation evaluation tasks and metrics. A non-linear mathematical model of the European supersonic transport aircraft has been synthesized on the final approach to land. Specific handling quality design criteria have been proposed to enable the non-linear dynamic inversion flight control laws to be designed, with piloted simulation used for validation. A pitch rate command system, with dynamics matched to the aircraft’s flight path response, will consistently provide Level 1 handling qualities. Nevertheless, pre-filtering the pilot’s input to provide a second order pitch rate response, using the author’s suggested revised constraints on the control anticipation parameter will generate the best handling qualities during the terminal phase of flight. The resulting pre-filter can be easily applied to non-linear dynamic inversion inner loop controllers and has simple and flight proven sensor requirements.

scholarly journals Robust dynamic inversion control of flight control system based on L1 adaptive structure

2021 ◽  
Vol 39 (5) ◽  
pp. 995-1004
Author(s):  
Yu LI ◽  
Xiaoxiong LIU ◽  
Ruichen MING ◽  
Shaoshan SUN ◽  
Weiguo ZHANG
Keyword(s):  
Control System ◽  
Flight Control ◽  
Dynamic Performance ◽  
Dynamic Inversion ◽  
Control Law ◽  
Flight Control System ◽  
Parameter Uncertainties ◽  
Strong Robustness ◽  
Adaptive Structure ◽  
The Stability

Nonlinear Dynamic Inversion(NDI) control has excellent rapidity and decoupling ability, unfortunately it lacks the essential robustness to disturbance. From the perspective of enhancing the robustness, an adaptive NDI method based on L1 adaptive structure is proposed. The L1 adaptive structure is introduced into the NDI control to enhance its robustness, which also guarantees the stability and expected dynamic performance of the system suffering from the disturbance influence. Secondly, the flight control law of the advanced aircraft is designed based on the present method to improve the robustness and fault tolerance of the flight control system. Finally, the effectiveness of the flight control law based on the present approach is verified under the fault disturbance. The results showed that the flight control law based on L1 adaptive NDI has excellent dynamic performance and strong robustness to parameter uncertainties and disturbances.

Design of Dynamic Inversion and Explicit Model Following Flight Control Laws for Quadrotor UAS

2020 ◽  
Vol 65 (3) ◽  
pp. 1-16
Author(s):  
Umberto Saetti ◽  
Joseph F. Horn ◽  
Sagar Lakhmani ◽  
Constantino Lagoa ◽  
Tom F. Berger
Keyword(s):  
Flight Control ◽  
Flight Test ◽  
Parametric Model ◽  
Unmanned Aerial Systems ◽  
Model Parameters ◽  
Dynamic Inversion ◽  
Explicit Model ◽  
Control Laws ◽  
Model Following ◽  
Novel Approach

The objectives of this paper are to advance dynamic inversion (DI) and explicit model following (EMF) flight control laws for quadrotor unmanned aerial systems (UAS) and to develop an efficient strategy to compute the stability and performance robustness statistics of such control laws given parametric model uncertainty. For this purpose, a parametric model of a quadrotor is identified from flight-test data. The identified model is validated both in frequency and time domains. Next, DI and EMF flight control laws are designed for both inner attitude and outer velocity loops. Finally, a novel approach based on an unscented transform is used to evaluate the statistics of the controller's performance based on the statistics of the uncertain model parameters.

Design UCAV Flight Control Law Based on Jamming Observer

2011 ◽  
Vol 66-68 ◽  
pp. 27-30
Author(s):  
Hai Wen Du ◽  
Xing Wei Weng ◽  
Yu Song Fu ◽  
Chuan Lin Tang
Keyword(s):  
Control System ◽  
Flight Control ◽  
System Stability ◽  
Good Stability ◽  
Dynamic Inversion ◽  
Control Law ◽  
Flight Control System ◽  
System A ◽  
Simulation Results

In order to study the nonlinear jamming problem in UCAV’s flight control system, a method of using observer to check the system’s jamming was designed, constructed robust dynamic inversion control law based on jamming observer. The simulation results show that the robust dynamic inversion control law based on jamming observer, make UCAV’s flight control system have good stability and robustness, it’s a great convenience analyzing the system stability.

scholarly journals Research on RBV Control Strategy of Large Angle Maneuver

2014 ◽  
Vol 2014 ◽  
pp. 1-11
Author(s):  
Jiangtao Xu ◽  
Na Luo ◽  
Yu Fu ◽  
Litong Wang ◽  
Xiande Wu
Keyword(s):  
Neural Network ◽  
Flight Control ◽  
Control Strategy ◽  
External Disturbance ◽  
Large Angle ◽  
Robust Adaptive Control ◽  
Dynamic Inversion ◽  
Sideslip Angle ◽  
Nonlinear Simulation ◽  
Robust Adaptive

Considering the hypersonic aerospace vehicle, with high dynamic, strong varying parameters, strong nonlinear, strong coupling, and the complicated flight environment, conventional flight control methods based on linear system may become invalid. To the high precision and reliable control problem of this vehicle, nonlinear flight control strategy based on neural network robust adaptive dynamic inversion is proposed. Firstly, considering the nonlinear characteristics of aerodynamic coefficients varying with Mach numbers, attack angle, and sideslip angle, the complete nonlinear 6-DOF model of RBV is established. Secondly, based on the time-scale separation, using the nonlinear dynamic inversion control strategy achieves the pseudolinear decoupling of RBV. And then, using the neural network with single hidden layer approximates the dynamic inversion error for system model uncertainty. Next, the external disturbance and network approximating error are suppressed by robust adaptive control. Finally, using Lyapunov’s theory proves that all error signals of closed loop system are uniformly bounded finally under this control strategy. Nonlinear simulation verifies the feasibility and validity of this control strategy to the RBV control system.

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