Differential Flatness-based Fast Trajectory Planning for Fixed-wing Unmanned Aerial Vehicles

Due to the strong nonlinearity and nonholonomic dynamics, despite that various general trajectory optimization methods have been presented, few of them can guarantee efficient compu-tation and physical feasibility for relatively complicated fixed-wing UAV dynamics. Aiming at this issue, this paper investigates a differential flatness-based trajectory optimization method for fixed-wing UAVs (DFTO-FW), which transcribes the trajectory optimization into a lightweight, unconstrained, gradient-analytical optimization with linear time complexity in each itera-tion to achieve fast trajectory generation. Through differential flat characteristics analysis and polynomial parameterization, the customized trajectory representation is presented, which implies the equality constraints to avoid the heavy computational burdens of solving complex dynamics. Through the design of integral performance costs and deduction of analytical gradients, the original trajectory optimization is transcribed into an uncon-strained, gradient-analytical optimization with linear time com-plexity to further improve efficiency. The simulation experi-ments illustrate the superior efficiency of the DFTO-FW, which takes sub-second CPU time against other competitors by orders of magnitude to generate fixed-wing UAV trajectories in ran-domly generated obstacle environments.

Information Utilization Ratio in Heuristic Optimization Algorithms

Heuristic algorithms are able to optimize objective functions efficiently because they use intelligently the information about the objective functions. Thus, information utilization is critical to the performance of heuristics. However, the concept of information utilization has remained vague and abstract because there is no reliable metric to reflect the extent to which the information about the objective function is utilized by heuristic algorithms. In this paper, the metric of information utilization ratio (IUR) is defined, which is the ratio of the utilized information quantity over the acquired information quantity in the search process. The IUR proves to be well-defined. Several examples of typical heuristic algorithms are given to demonstrate the procedure of calculating the IUR. Empirical evidences on the correlation between the IUR and the performance of a heuristic are also provided. The IUR can be an index of how finely an algorithm is designed and guide the invention of new heuristics and the improvement of existing ones.

A Cooperative Framework for Fireworks Algorithm

This paper presents a cooperative framework for fireworks algorithm (CoFFWA). A detailed analysis of existing fireworks algorithm (FWA) and its recently developed variants has revealed that (i) the selection strategy lead to the contribution of the firework with the best fitness (core firework) for the optimization overwhelms the contributions of the rest of fireworks (non-core fireworks) in the explosion operator, (ii) the Gaussian mutation operator is not as effective as it is designed to be. To overcome these limitations, the CoFFWA is proposed, which can greatly enhance the exploitation ability of non-core fireworks by using independent selection operator and increase the exploration capacity by crowdness-avoiding cooperative strategy among the fireworks. Experimental results on the CEC2013 benchmark functions suggest that CoFFWA outperforms the state-of-the-art FWA variants, artificial bee colony, differential evolution, the standard particle swarm optimization (SPSO) in 2007 and the most recent SPSO in 2011 in term of convergence performance.

Introduction and Ranking Results of the ICSI 2014 Competition on Single Objective Optimization

This technical report includes the introduction and ranking results of the ICSI 2014 Competition on Single Objective Optimization.