Computer Methods in Applied Mechanics and Engineering

In this paper, we propose and investigate a new local search strategy for multiobjective memetic algorithms. More precisely, we suggest a novel iterative search procedure, known as the Hill Climber with Sidestep (HCS), which is designed for the treatment of multiobjective optimization problems, and show further two possible ways to integrate the HCS into a given evolutionary strategy leading to new memetic (or hybrid) algorithms. The pecularity of the HCS is that it is intended to be capable both moving toward and along the (local) Pareto set depending on the distance of the current iterate toward this set. The local search procedure utilizes the geometry of the directional cones of such optimization problems and works with or without gradient information. Finally, we present some numerical results on some well-known benchmark problems, indicating the strength of the local search strategy as a standalone algorithm as well as its benefit when used within a MOEA. For the latter we use the state of the art algorithms Nondominated Sorting Genetic Algorithm-II and Strength Pareto Evolutionary Algorithm 2 as base MOEAs.

HCS: A New Local Search Strategy for Memetic Multiobjective Evolutionary Algorithms

Nowadays, the solution of multiobjective optimization problems in aeronautical and aerospace engineering has become a standard practice. These two fields offer highly complex search spaces with different sources of difficulty, which are amenable to the use of alternative search techniques such as metaheuristics, since they require little domain information to operate. From the several metaheuristics available, multiobjective evolutionary algorithms (MOEAs) have become particularly popular, mainly because of their availability, ease of use, and flexibility. This paper presents a taxonomy and a comprehensive review of applications of MOEAs in aeronautical and aerospace design problems. The review includes both the characteristics of the specific MOEA adopted in each case, as well as the features of the problems being solved with them. The advantages and disadvantages of each type of approach are also briefly addressed. We also provide a set of general guidelines for using and designing MOEAs for aeronautical and aerospace engineering problems. In the final part of the paper, we provide some potential paths for future research, which we consider promising within this area.

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Multiobjective Evolutionary Algorithms in Aeronautical and Aerospace Engineering

AIAA Guidance, Navigation, and Control Conference

In this paper a comparative assessment of the effectiveness of different deviation methods for Near Earth Objects is presented. Specifically, solar collector, nuclear interceptor, kinetic impactor, low-thrust propulsion, mass driver and gravity tug are modelled and compared. For each method, a mathematical model is developed in order to compute the achievable deviation. A multi-criteria optmization method is then used to construct the set of Pareto optimal solutions, minimizing the mass of the spacecraft at departure from the Earth and the warning time, i.e., the time from launch to the foreseen impact of the asteroid with the Earth, while at the same time maximizing the deviation. A dominance criterion is defined and used to compare all the Pareto sets for all the various mitigation strategies. Finally a Technology Readiness Level factor is associated to each strategy in order to estimate the required technological development.

/pdf/multicriteria-comparison-among-several-mitigation-strategies-5fpsotej8e.pdf

Multicriteria Comparison Among Several Mitigation Strategies for Dangerous Near-Earth Objects

https://strathprints.strath.ac.uk/40476/1/Vasile_M_Maddock_C_Pure_Design_of_a_formation_of_solar_pumped_lasers_for_asteroid_deflection_Jul_2012.pdf

Design of a formation of solar pumped lasers for asteroid deflection

This paper presents an analysis of an asteroid deflection method based on multiple solar concentrators. A model of the deflection through the sublimation of the surface material of an asteroid is presented, with simulation results showing the achievable impact parameter with, and without, accounting for the effects of mirror contamination due to the ejected debris plume. A second model with simulation results is presented analyzing an enhancement of the Yarkovsky effect, which provides a significant deflection even when the surface temperature is not high enough to sublimate. Finally the dynamical model of solar concentrators in the proximity of an irregular celestial body are discussed, together with a Lyapunov-based controller to maintain the spacecraft concentrators at a required distance from the asteroid.

/pdf/on-the-deflection-of-asteroids-with-mirrors-5ggvor94z3.pdf

On the deflection of asteroids with mirrors

With the increased interest and attention to Near Earth Objects, there have been many proposals of possible methods of deviating of those objects potentially posing a threat to Earth. One such conceptual method envisioned sublimating the surface material of an asteroid using solar energy directed by mirrors onboard an orbiting or hovering spacecraft. In this paper, this method is examined in more detail, with an emphasis on feasibility. A comparison is made between the complexities of deploying and operating a single large rigid structure around asteroids, with that of a formation of smaller spacecraft. Configurations are presented for different Near Earth Asteroids (NEA), duration of thrust, and achieved deflections. Both simplistic single flat mirror and more complex parabolic reflector‐lens assemblies are examined, comparing the initial spacecraft mass and payload sizing for various formation sizes. Relative periodic formation orbits are found accounting for perturbations due to the Sun and NEA, and for the solar pressure on the mirror payload on the spacecraft.

/pdf/comparison-of-single-and-multi-spacecraft-configurations-for-2pk4nqnkk8.pdf

Comparison of Single and Multi-Spacecraft Configurations for NEA Deflection by Solar Sublimation

Purpose – The purpose of this paper is to present a methodology and experimental results on using global optimization algorithms to determine the optimal orbit, based on the mission requirements, for a set of spacecraft flying in formation with an asteroid.Design/methodology/approach – A behavioral‐based hybrid global optimization approach is used to first characterize the solution space and find families of orbits that are a fixed distance away from the asteroid. The same optimization approach is then used to find the set of Pareto optimal solutions that minimize both the distance from the asteroid and the variation of the Sun‐spacecraft‐asteroid angle. Two sample missions to asteroids, representing constrained single and multi‐objective problems, were selected to test the applicability of using an in‐house hybrid stochastic‐deterministic global optimization algorithm (Evolutionary Programming and Interval Computation (EPIC)) to find optimal orbits for a spacecraft flying in formation with an orbit. The ...

/pdf/design-of-optimal-spacecraft-asteroid-formations-through-a-2tm2d7jtdy.pdf

Design of optimal spacecraft-asteroid formations through a hybrid global optimization approach

This paper presents a novel approach to the solution of multiphase multi-objective optimal control problems. The proposed solution strategy is based on the transcription of the optimal control prob...

/pdf/direct-solution-of-multi-objective-optimal-control-problems-1118a5nenq.pdf

Christie Alisa Maddock

Papers

Design of a formation of solar pumped lasers for asteroid deflection

On the deflection of asteroids with mirrors

Comparison of Single and Multi-Spacecraft Configurations for NEA Deflection by Solar Sublimation

Design of optimal spacecraft-asteroid formations through a hybrid global optimization approach

Direct Solution of Multi-Objective Optimal Control Problems Applied to Spaceplane Mission Design