Lihua Zhu^1,*, Yu Wang¹, Zhiqiang Wu¹, Cheire Cheng²

Intelligent Automation & Soft Computing, Vol.33, No.1, pp. 291-303, 2022, DOI:10.32604/iasc.2022.024252

Abstract The rapid developments of artificial intelligence in the last decade are influencing aerospace engineering to a great extent and research in this context is proliferating. In this paper, the trajectory optimization of a three-stage launch vehicle in the powering phase subject to the sun-synchronous orbit is considered. To solve the optimal control problem, the Gauss pseudo-spectral method (GPM) is used to transform the optimization model to a nonlinear programming (NLP) problem and sequential quadratic programming is applied to find the optimal solution. However, the sensitivity of the initial guess may cost the solver significant time to do the Newton iteration… More >

Jian Ma^1,2, Changxuan Wen³, Chen Zhang^2,*

CMES-Computer Modeling in Engineering & Sciences, Vol.126, No.2, pp. 617-644, 2021, DOI:10.32604/cmes.2021.014474

Abstract High-specific-impulse electric propulsion technology is promising for future space robotic debris removal in sun-synchronous orbits. Such a prospect involves solving a class of challenging problems of low-thrust orbital rendezvous between an active spacecraft and a free-flying debris. This study focuses on computing optimal low-thrust minimum-time many-revolution trajectories, considering the effects of the Earth oblateness perturbations and null thrust in Earth shadow. Firstly, a set of mean-element orbital dynamic equations of a chaser (spacecraft) and a target (debris) are derived by using the orbital averaging technique, and specifically a slow-changing state of the mean longitude difference is proposed to accommodate to… More >

Liu Duo-Neng^1,2, Hou Zhong-Xi¹, Guo Zheng¹, Yang Xi-Xiang¹, Gao Xian-Zhong¹

CMES-Computer Modeling in Engineering & Sciences, Vol.111, No.6, pp. 531-565, 2016, DOI:10.3970/cmes.2016.111.531

Abstract Dynamic soaring is a flight maneuver to exploit gradient wind field to extend endurance and traveling distance. Optimal trajectories for permissible wind conditions are generated for loitering dynamic soaring as well as for traveling patterns with a small unmanned aerial vehicle. The efficient direct collection approach based on the Runge-Kutta integrator is used to solve the optimization problem. The fast convergence of the optimization process leads to the potential for real-time applications. Based on the results of trajectory optimizations, the general permissible wind conditions which involve the allowable power law exponents and feasible reference wind strengths supporting dynamic soaring are… More >

B. J. Zhu^1,2, Z. X. Hou¹, X. Z. Wang³, Q. Y. Chen¹

CMES-Computer Modeling in Engineering & Sciences, Vol.106, No.5, pp. 357-377, 2015, DOI:10.3970/cmes.2015.106.357

Abstract The paper presents a comprehensive study on the performance of long endurance and long distance trajectory optimization of engineless UAV in dynamic soaring. A dynamic model of engineless UAV in gradient wind field is developed. Long endurance and long distance trajectory optimization problems are modelled by non-linear optimal control equations. Two different boundary conditions are considered and results are compared: (i) open long endurance pattern, (ii) closed long endurance pattern, (iii) open long distance pattern. In patterns of (i) and (ii), the UAV return to original position with the maximum flying time in pattern (ii) , and in patterns of… More >