Application of Approximate I/O Linearization to Aircraft Flight Control

1994 ◽  
Vol 116 (3) ◽  
pp. 429-436 ◽  
Author(s):  
A. W. Lee ◽  
J. K. Hedrick
Keyword(s):  
Control Problem ◽  
Flight Control ◽  
Closed Loop ◽  
Performance Enhancement ◽  
Design Method ◽  
Loop System ◽  
Closed Loop System ◽  
Aircraft Flight Control ◽  
Original Plant ◽  
Control Saturation

This paper examines the performance enhancement of a statically unstable aircraft subject to the input and state constraints. Under control saturation, i/o linearizability is destroyed and the state trajectories may not be attracted to the sliding surface. If the reference signals are sufficiently large and the zero-dynamics is lightly damped, the i/o linearizing control may become unreasonably large in magnitude, making the closed-loop system susceptible to the damaging effects of control saturation. In addition to performance degradations such as increased tracking errors, control saturation can drive the closed-loop system to instability. In this paper, a new design method called approximate i/o linearization is presented to enhance the performance of the SISO longitudinal flight control problem under saturation. The new approximate i/o linearization law is obtained by solving a pointwise minimization problem. The function to be minimized consists of a surface whose relative degree is one, its derivative, and weighted square of the input u. The advantages of the approximate i/o linearization is that the adverse effects of control saturation can be minimized by properly selecting the weight on the usage of the control. The only requirement for the new technique is that the original plant be locally i/o linearizable. Thus approximate i/o linearization does not impose additional strict requirements on the plant. In the remaining sections of the paper, stability and bounded tracking properties of the approximate i/o linearization are proven. Finally, a longitudinal flight control problem is used to demonstrate the application of approximate i/o linearization.

The Application of Fractional Order Calculus in Closed-Loop System Control

2012 ◽  
Vol 442 ◽  
pp. 315-320
Author(s):  
Yun Fang Feng
Keyword(s):  
Closed Loop ◽  
Design Method ◽  
Open Loop ◽  
Loop System ◽  
System Control ◽  
Closed Loop System ◽  
Open Loop System ◽  
System Robustness ◽  
Fractional Controller ◽  
Frequency Phase

A design method of fractional controller has been developed to meet the five different specifications, including for the closed-loop system robustness. The specifications of cross frequency, phase to get financing ϕ meters and robustness and complete performance curve based on level off the stage of open loop system, ensure damping is worse reaction time of model uncertainty gain change.

Passivity-Based Stabilization of Underactuated Mechanical Systems

2013 ◽  
Vol 421 ◽  
pp. 16-22
Author(s):  
Shan Shan Wu ◽  
Wei Huo
Keyword(s):  
Closed Loop ◽  
Control Method ◽  
Controller Design ◽  
Design Method ◽  
Mechanical Systems ◽  
Matching Condition ◽  
Loop System ◽  
Closed Loop System ◽  
Underactuated Mechanical Systems ◽  
Stabilization Control

A new stabilization control method for underactuated linear mechanical systems is presented in this paper. By proper setting the desired closed-loop system, the matching condition for controller design is reduced to one equation and an adjustable parameter (damping coefficient) is introduced to the controller. Stability of the closed-loop system is proved based on passivity. As an application example, stabilization control of 2-DOF Pendubot is studied. The system is linearized at its equilibrium point and the proposed controller design method is applied to the linearized system. The procedure of solving matching condition and design controller for the Pendubot is provided. The simulation results verify feasibility of the proposed method.

Flight Control Law Design Using Dynamic Inversion for Linear Parameter Varying Systems

1998 ◽  
Vol 120 (2) ◽  
pp. 200-207 ◽  
Author(s):  
D. Malloy ◽  
B. C. Chang
Keyword(s):  
Flight Control ◽  
Closed Loop ◽  
Broad Class ◽  
Nonlinear Function ◽  
Loop System ◽  
Linear Parameter ◽  
Closed Loop System ◽  
Outer Loop ◽  
Linear Parameter Varying ◽  
Parameter Varying

A regulator design technique is presented for linear parameter varying (LPV) systems. This technique may be applied to many different types of systems, including nonlinear, due to the broad class of systems that may be represented by LPVs. The regulator, consisting of an inner loop and an outer loop, renders the closed-loop system’s steady-state input-output to be linear time invariant (LTI) and causes the output to track a commanded trajectory. With real-time, accurate parameter data, the inner loop effectively cancels the parameter dependent terms. The outer loop is designed using LTI H∞ synthesis to enable the closed loop system to meet stability and performance goals. Due to the inner loop controller and imperfect parameter cancellation, the complete closed-loop system is likely to be a nonlinear function of the parameters and their derivatives. To assess the stability using the quadratic Lyapunov test, we model the closed-loop system as a polytopic system. The key ideas are illustrated with a nonlinear aircraft flight control example.

Robust Control of Double-Machine Wind Turbines with DFIG Using Hamiltonian Energy Method

2012 ◽  
Vol 443-444 ◽  
pp. 941-947
Author(s):  
Bing Wang ◽  
Xiao Ling Yuan ◽  
Jin Zhu
Keyword(s):  
Robust Control ◽  
Control Problem ◽  
Wind Turbines ◽  
Energy Method ◽  
Closed Loop ◽  
Loop System ◽  
Closed Loop System ◽  
Machine System ◽  
Nonlinear Design ◽  
Finite Gain

- In this paper, the robust control problem of the doubly fed induction generator (DFIG) wind turbines is investigated based on Hamiltonian energy method. A nonlinear design method is proposed for the double-machine system, such that the closed-loop system is stable simultaneously under the action of the controller. Moreover, we study the robust control problem of double-machine system in the presence of disturbances. On the basis of the proposed theorem, the Hamiltonian controller is designed to render the closed-loop system finite-gain stable. In order to illustrate the effectiveness of the proposed method, the simulations are performed which show that the gotten nonlinear controller can enhance the transient stability and improve the robustness property of the closed-loop system.

Longitudinal nonlinear adaptive autopilot design for missiles with control constraint

2017 ◽  
Vol 232 (9) ◽  
pp. 1655-1670 ◽  
Author(s):  
Keum W Lee ◽  
Sahjendra N Singh
Keyword(s):  
Feedback Loop ◽  
Closed Loop ◽  
Angle Of Attack ◽  
Trajectory Control ◽  
Loop System ◽  
Control Law ◽  
Control Input ◽  
Error Signal ◽  
Closed Loop System ◽  
Control Saturation

This paper develops a new nonlinear adaptive longitudinal autopilot for the control of missiles with control input constraint, in the presence of parametric uncertainties and external disturbance input. The objective here is to control the angle of attack of the missile. A saturating control law is derived for the trajectory control of the angle of attack. The control law includes an auxiliary dynamic system in the feedback loop, driven by control input error signal, caused by control saturation, to preserve stability in the closed-loop system. By the Lyapunov stability analysis, it is shown that in the closed-loop system, the system trajectories are uniformly ultimately bounded. Simulation results show that the designed autopilot with constrained input can accomplish accurate trajectory control if the control saturation period is short. It is also seen that although the tracking error increases with the saturation period, the angle of attack tends to zero, once the command input is set to zero. Furthermore this adaptive control system, including the control error signal feedback loop, performs better than the adaptive laws, designed earlier based on immersion and invariance principle, without control magnitude constraint.

Parameterized Regulator Design Method for Switched Linear Systems

2006 ◽  
Author(s):  
Zhizheng Wu ◽  
Foued Ben Amara
Keyword(s):  
Linear Systems ◽  
Closed Loop ◽  
Design Method ◽  
Loop System ◽  
Closed Loop System ◽  
Switched Linear System ◽  
Switched Linear Systems ◽  
Central Controller ◽  
Synthesis Approach ◽  
System Switching

In this paper, a parameterized regulator design method based on bilinear matrix inequalities (BMIs) is presented for switched linear systems, where it is desired to reject known disturbance signals and/or track known reference inputs. Switching among plant models as well among disturbance and reference signals is defined according to a switching surface. The regulator design approach consists of three steps. The first step consists of constructing a switched observer-based state-feedback central controller for the switched linear system. Switching in the controller is performed according to the same switching rule as in the plant. The second step involves augmenting the switched central-controller to construct a parameterized set of switched controllers. Conditions for internal stability of the resulting switched closed loop system are presented. In the third step, regulation conditions are derived for the switched closed loop system. Based on the regulation conditions, a regulator synthesis approach is proposed based on solving properly formulated BMIs. Finally, a numerical example is presented to illustrate the performance of the proposed regulator.

Autonomous Mission Management Based Nonlinear Flight Control Design for a Class of Hybrid Unmanned Aerial Vehicles

2021 ◽  
Vol 01 (02) ◽  
pp. 2150009
Author(s):  
Kemao Peng
Keyword(s):  
Flight Control ◽  
Closed Loop ◽  
Main Idea ◽  
Loop System ◽  
Control Law ◽  
Closed Loop System ◽  
Control Laws ◽  
Mission Management ◽  
Rotary Wing ◽  
Transition Flight

In this paper, a nonlinear flight control law is designed for a hybrid unmanned aerial vehicle (UAV) to achieve the advanced flight performances with the autonomous mission management (AMM). The hybrid UAV is capable of hovering like quadrotors and maneuvering as fixed-wing aircraft. The main idea is to design the flight control laws in modules. Those modules are organized online by the autonomous mission management. Such online organization will improve the UAV autonomy. One of the challenges is to execute the transition flight between the rotary-wing and fixed-wing modes. The resulting closed-loop system with the designed flight control law is verified in simulation and the simulation results demonstrate that the resulting closed-loop system can successfully complete the designated flight missions including the transition flight between the rotary-wing and fixed-wing modes.

Design of Compensators for Actuator Saturation

1995 ◽  
Vol 209 (3) ◽  
pp. 157-164 ◽  
Author(s):  
C W Chan ◽  
K Hui
Keyword(s):  
Control Problem ◽  
Closed Loop ◽  
Actuator Saturation ◽  
Design Procedure ◽  
Loop System ◽  
Linear Control ◽  
Closed Loop System ◽  
Set Point ◽  
Non Linear ◽  
Linear Disturbance

Actuator saturation is a common non-linear control problem; if it is not being compensated properly, the system can become unstable. When the actuator saturates, the control that cannot be implemented can be interpreted as a non-linear disturbance being injected into the closed-loop system. After transformation, the applied set-point is altered by the disturbance, giving the effective set-point. If the effective instead of the applied set-point is used to calculate the control, no actuator saturation occurs. Since the effective set-point always replaces the applied set-point whenever the actuator saturates, a compensator can be designed aiming to produce a more acceptable effective set-point. The conditions for its implementation are given, followed by the properties of the effective set-point. A procedure for selecting the parameter of the compensator is also described. Examples are presented to illustrate the design procedure and to compare the performance of the proposed and the existing compensators.

Research on ANN Dynamic Inversion Control of UAV

2012 ◽  
Vol 466-467 ◽  
pp. 1353-1357 ◽  
Author(s):  
Wei Lun Chen ◽  
Gong Cai Xin
Keyword(s):  
Control Systems ◽  
Flight Control ◽  
Delay Time ◽  
Closed Loop ◽  
Reference Value ◽  
Loop System ◽  
Dynamic Inversion ◽  
Closed Loop System ◽  
Hidden Layer ◽  
The Stability

The paper proposes a method to design AANN dynamic inversion controller through online ANN compensating inversion error. It mainly aims at evident shortage of dynamic inversion controller of UAV. A single hidden layer ANN structure is constructed and the stability of the whole closed loop system is proved. Also the stable adjustment arithmetic of online ANN weight is proposed. The robustness, the adaptability to fault and the response capability to actuator delay time of the scheme are verified by simulation. It is also proved that the online ANN has improved the performance of dynamic inversion controller well. It has important reference value for designing advanced flight control systems of UAV.

Sampled-data mixed H∞ and passive control for attitude stabilization and vibration suppression of flexible spacecrafts with input delay

2018 ◽  
Vol 24 (22) ◽  
pp. 5401-5417 ◽  
Author(s):  
Baolong Zhu ◽  
Zhiping Zhang ◽  
Mingliang Suo ◽  
Ying Chen ◽  
Shunli Li
Keyword(s):  
Closed Loop ◽  
Passive Control ◽  
Vibration Suppression ◽  
Design Method ◽  
Performance Criterion ◽  
Loop System ◽  
Linear Matrix ◽  
Time Varying ◽  
Sampled Data ◽  
Closed Loop System

This paper deals with the problem of mixed [Formula: see text] and passive control for flexible spacecrafts subject to nonuniform sampling and time-varying delay in the input channel. An impulsive observer-based controller is introduced and the resulting closed-loop system is a hybrid system consisting of a continuous time-delay subsystem and an impulsive differential subsystem. As a first result, we derive a generalized bounded real lemma (GBRL), that is, a generalized [Formula: see text] performance criterion, for the impulsive differential subsystem by constructing a time-varying Lyapunov functional. Then, on the basis of this GBRL and utilizing the Lyapunov–Krasovskii approach, a sufficient condition is derived to asymptotically stabilize the closed-loop system and simultaneously guarantee a prescribed mixed [Formula: see text] and passivity performance index. A design method is proposed for the desired controller, which can be readily constructed by solving a convex optimization problem with linear matrix inequalities (LMIs) constraints. Finally, numerical experiments are provided to support the theoretical results, and comparisons with former approaches are also discussed.

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