A Comparative Study on Multidisciplinary and Multi-objective Optimal Control Design of an Aircraft Wing with Multiple Aileron

This paper presents a multidisciplinary and multi-objective optimal design of an aircraft wing with two, three, and four control surfaces. The study aims to compare the performance of the wing in terms of aerodynamic loads rejection, stability robustness, and energy consumption. An LQR (Linear Quadratic Regulator) is designed for each control surface. The geometrical parameters of the control surfaces such as the span-wise and chord lengths, and the diagonal elements of the LQR weighting matrices are optimally adjusted by the NSGA-II (Non-dominated Sorting Genetic Algorithm). The algorithm returns a set of solutions called the Pareto set and its function evaluation forms another set known as the Pareto front. The solution set holds optimal geometrical and control decision variables that produce various degrees of optimal trade-offs among the design goals. To facilitate the comparison between the three optimization problems, a post-processing algorithm that operates on the Pareto front is utilized. Then, the knee points and portions of the Pareto fronts are compared. The optimal solutions show that there are conflicting relationships between the design objectives. The disturbance rejection of the wing with the two ailerons is the least effective however control energy consumption is the smallest as compared to the other configurations. The wing with the three ailerons at 18 different design options has the best relative stability. At the knee point, a wing having four control surfaces can offer the best disturbance rejection but at the expense of the control energy. With these considerations, a wing with three surfaces can be the best compromise among the other configurations.