Adaptive feedforward control for crosswind landing with variable step size

2021 ◽  
pp. 095441002110054
Author(s):  
Qi Bian ◽  
Menghan Zhang ◽  
Jian Ma
Keyword(s):  
Control System ◽  
Flight Control ◽  
Feedforward Control ◽  
Variable Step Size ◽  
Test Bed ◽  
Step Size ◽  
Aircraft Landing ◽  
Variable Step ◽  
The Stability ◽  
Crosswind Landing

In this article, a modified Steiglitz–McBride (SM) structure with variable step size is proposed for aircraft feedforward control to reduce lateral landing deviation in the presence of crosswind disturbance. Currently, most of the aircraft landing studies focus on the trajectory tracking problems in the longitudinal plane and seldom focus on lateral disturbances. This article develops a modified SM structure–based feedforward control system to online estimate both the primary path and the control path (secondary path), where a fuzzy logic–based variable step size strategy is implemented to ensure fast convergence rate and strong robustness under complex crosswind scenarios. As a consequence, the lateral deviation during crosswind landing could be largely reduced as fast as possible while the stability of the flight control system is maintained. A Boeing 747 model is used as a test bed, and the simulations are carried out on two different crosswind conditions to demonstrate the feasibility and effectiveness of the proposed method.

Variable-step-size second-order-derivative multistep method for solving first-order ordinary differential equations in system simulation

2020 ◽  
Vol 11 (01) ◽  
pp. 2050001
Author(s):  
Lei Zhang ◽  
Chaofeng Zhang ◽  
Mengya Liu
Keyword(s):  
Differential Equations ◽  
Numerical Method ◽  
Multistep Method ◽  
Second Order ◽  
Order Derivative ◽  
Variable Step Size ◽  
Variable Order ◽  
Step Size ◽  
Variable Step ◽  
The Stability

According to the relationship between truncation error and step size of two implicit second-order-derivative multistep formulas based on Hermite interpolation polynomial, a variable-order and variable-step-size numerical method for solving differential equations is designed. The stability properties of the formulas are discussed and the stability regions are analyzed. The deduced methods are applied to a simulation problem. The results show that the numerical method can satisfy calculation accuracy, reduce the number of calculation steps and accelerate calculation speed.

Adaptive IIR Filter Using Variable Step Size for Active Noise Control Inside a Short Duct

2008 ◽  
Author(s):  
Ho-Wuk Kim ◽  
Sang-Kwon Lee
Keyword(s):  
Control System ◽  
Noise Control ◽  
Active Noise Control ◽  
Fir Filter ◽  
Variable Step Size ◽  
Step Size ◽  
Iir Filter ◽  
Active Noise ◽  
Lms Filter ◽  
Variable Step

FIR filter for a adaptive filter algorithm, is mostly used for an active noise control system. However, FIR filter needs to have more large size of the filter length than it of IIR filter. Therefore, the control system using FIR adaptive filter has slow calculation time. In the active noise control system of the short duct, the reference signal can be affected by the output signal, so IIR filter for ARMA system can be more suitable for the active noise control of the short duct than FIR filter for MA system. In this paper, the recursive LMS filter, which is adaptive IIR filter, is applicated for the active noise control inside the short duct. For faster convergence and more accurate control, a variable step size algorithm is introduced for this recursive LMS filter (R-VSSLMS filter). Using this algorithm and considering the secondary path, the filtered-u R-VSSLMS is conducted successfully on the real experiment in the short duct. The performance of the active control using the filtered-u R-VSSLMS filter, is compared with the performance of the active control using a filtered-x LMS filter.

The stability of variable step-size LMS algorithms

1999 ◽  
Vol 47 (12) ◽  
pp. 3277-3288 ◽  
Author(s):  
S.B. Gelfand ◽  
Yongbin Wei ◽  
J.V. Krogmeier
Keyword(s):  
Variable Step Size ◽  
Step Size ◽  
Variable Step ◽  
The Stability

scholarly journals Variable Step Size Adams Methods for BSDEs

2021 ◽  
Vol 2021 ◽  
pp. 1-13
Author(s):  
Qiang Han
Keyword(s):  
High Order ◽  
Variable Step Size ◽  
Necessary And Sufficient Condition ◽  
Step Size ◽  
Truncation Errors ◽  
Adams Methods ◽  
Variable Step ◽  
High Order Convergence ◽  
The Stability ◽  
Necessary And Sufficient

For backward stochastic differential equations (BSDEs), we construct variable step size Adams methods by means of Itô–Taylor expansion, and these schemes are nonlinear multistep schemes. It is deduced that the conditions of local truncation errors with respect to Y and Z reach high order. The coefficients in the numerical methods are inferred and bounded under appropriate conditions. A necessary and sufficient condition is given to judge the stability of our numerical schemes. Moreover, the high-order convergence of the schemes is rigorously proved. The numerical illustrations are provided.

A Class of Methods with Optimal Stability Properties for the Numerical Solution of IVPs: Construction and Implementation

2017 ◽  
Vol 14 (01) ◽  
pp. 1750007
Author(s):  
Masoumeh Hosseini Nasab ◽  
Gholamreza Hojjati ◽  
Ali Abdi
Keyword(s):  
Numerical Solution ◽  
Numerical Experiments ◽  
Point Of View ◽  
Variable Step Size ◽  
Second Derivative ◽  
Step Size ◽  
Stability Properties ◽  
Variable Step ◽  
The Stability ◽  
Size Mode

Considering the methods with future points technique from second derivative general linear methods (SGLMs) point of view, makes it possible to improve their stability properties. In this paper, we extend the stability regions of a modified version of E2BD formulas to optimal one and show its effectiveness by numerical verifications. Also, implementation issues, with numerical experiments, of these methods are investigated in a variable step-size mode.

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