Hybrid Evolutionary Optimisation Methods for the Clearance of Nonlinear Flight Control Laws

Flying in formation improves aerodynamic efficiency and, consequently, leads to an energy savings. One strategy for formation control is to follow the preceding vehicle. Many researchers have shown through simulation results and analysis of specific control laws that this strategy leads to amplification of disturbances as they propagate through the formation. This effect is known as string instability. In this paper, we show that string instability is due to a fundamental constraint on coupled feedback loops. The tradeoffs imposed by this constraint imply that predecessor following is an inherently poor strategy for formation flight control. Finally, we present two examples that demonstrate the theoretical results.

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Automatic Flight Control of Unmanned Helicopter Based on Nonlinear Model

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.472-475.1492 ◽

2012 ◽

Vol 472-475 ◽

pp. 1492-1499

Author(s):

Run Xia Guo

Keyword(s):

Nonlinear Model ◽

Flight Control ◽

Attitude Control ◽

Lyapunov Stability Theory ◽

Test Results ◽

Unmanned Helicopter ◽

Control Laws ◽

Control Approach ◽

State Dependent ◽

Compensation Technique

The Unmanned helicopter (UMH) movement was divided into two parts, namely, attitude and trajectory motion. And then a two-timescale nonlinear model was established. The paper improved and expanded state dependent riccati equation (SDRE) control approach, deriving analytical conditions for achieving global asymptotic stability with lyapunov stability theory. Proof was given. By combining improved SDRE control with nonlinear feed-forward compensation technique, the full envelop flight attitude control laws could be designed. On the basis of attitude control, trajectory controller was developed. Actual flight tests were carried out. Test results show that the control strategy is highly effective.

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Multi-Mode Wave Energy Converter Design Optimisation Using an Improved Moth Flame Optimisation Algorithm

Energies ◽

10.3390/en14133737 ◽

2021 ◽

Vol 14 (13) ◽

pp. 3737

Author(s):

Mehdi Neshat ◽

Nataliia Sergiienko ◽

Seyedali Mirjalili ◽

Meysam Majidi Nezhad ◽

Giuseppe Piras ◽

...

Keyword(s):

Wave Energy ◽

Wave Energy Converter ◽

Total Power ◽

Energy Converter ◽

Wave Regime ◽

Optimisation Algorithm ◽

Wide Range ◽

Evolutionary Optimisation ◽

Optimisation Methods ◽

Optimisation Algorithms

Ocean renewable wave power is one of the more encouraging inexhaustible energy sources, with the potential to be exploited for nearly 337 GW worldwide. However, compared with other sources of renewables, wave energy technologies have not been fully developed, and the produced energy price is not as competitive as that of wind or solar renewable technologies. In order to commercialise ocean wave technologies, a wide range of optimisation methodologies have been proposed in the last decade. However, evaluations and comparisons of the performance of state-of-the-art bio-inspired optimisation algorithms have not been contemplated for wave energy converters’ optimisation. In this work, we conduct a comprehensive investigation, evaluation and comparison of the optimisation of the geometry, tether angles and power take-off (PTO) settings of a wave energy converter (WEC) using bio-inspired swarm-evolutionary optimisation algorithms based on a sample wave regime at a site in the Mediterranean Sea, in the west of Sicily, Italy. An improved version of a recent optimisation algorithm, called the Moth–Flame Optimiser (MFO), is also proposed for this application area. The results demonstrated that the proposed MFO can outperform other optimisation methods in maximising the total power harnessed from a WEC.

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Enhanced Disturbance-Observer-Based Control for a Class of Time-Delay System with Uncertain Sinusoidal Disturbances

Mathematical Problems in Engineering ◽

10.1155/2013/805687 ◽

2013 ◽

Vol 2013 ◽

pp. 1-8 ◽

Cited By ~ 2

Author(s):

Xinyu Wen

Keyword(s):

Time Delay ◽

Flight Control ◽

Disturbance Observer ◽

Delay System ◽

Delay Systems ◽

Flight Control System ◽

Control Laws ◽

Nonlinear Disturbance Observer ◽

Dynamic Performances ◽

Uncertain Disturbance

This paper is concerned with disturbance-observer-based control (DOBC) for a class of time-delay systems with uncertain sinusoidal disturbances. The disturbances are decomposed as precise and uncertain parts using nonlinear disturbance observer (DO) after appropriate coordinate transformation. And then the two parts can be compensated by corresponding controller, respectively, such that the classic DOBC method is extended to uncertain disturbance rejection. One novel feature of the proposed method is that even if the precise disturbance parameters are inaccessible, the merits of DOBC can be inherited. By integrating the disturbance observers with feedback control laws with time delay, the disturbances can be rejected and the desired dynamic performances can be guaranteed. Finally, simulations for a flight control system are given to demonstrate the effectiveness of the results.

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