Reza Esmaelzadeh; Abolghasem Naghash; mahdi mortazavi
Volume 10, Issue 3 , December 2017, , Pages 15-24
Abstract
An optimal explicit guidance law that maximizes terminal velocity is developed for the reentry of a vehicle to a fixed target. The equations of motion are reduced with differential flatness approach and acceleration commands are related to the parameters of trajectory. An optimal trajectory is determined ...
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An optimal explicit guidance law that maximizes terminal velocity is developed for the reentry of a vehicle to a fixed target. The equations of motion are reduced with differential flatness approach and acceleration commands are related to the parameters of trajectory. An optimal trajectory is determined by solving a real-coded genetic algorithm. For online trajectory generation, optimal trajectory is approximated. The approximated trajectory is compared with the pure proportional navigation and genetic algorithm solutions. The near optimal terminal velocity solution compares very well with these solutions. The approach robustness is examined by Monte Carlo simulation. Other advantages such as trajectory representation with minimum parameters, applicability to any reentry vehicle configuration and any control scheme, and Time-to-Go independency make this guidance approach more favorable.
R. Esmaelzadeh
Volume 6, Issue 4 , January 2014, , Pages 29-36
Abstract
An explicit guidance law is developed for a reentry vehicle. Motion is constrained to a three-dimensional Bezier curve. Acceleration commands are derived by solving an inverse problem that combined with differential flatness approach. Trajectory is related to Bezier parameters. A comparison with pure ...
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An explicit guidance law is developed for a reentry vehicle. Motion is constrained to a three-dimensional Bezier curve. Acceleration commands are derived by solving an inverse problem that combined with differential flatness approach. Trajectory is related to Bezier parameters. A comparison with pure proportional navigation shows the same accuracy, but a higher capability for optimal trajectory to some degree. Other advantages such as trajectory representation with minimum parameters, applicability to any reentry vehicle configuration and any control scheme, and Time-to-Go independency make this guidance approach more favorable.
A. R. Alemi Naeeni; J. Roshanian
Volume 6, Issue 4 , January 2014, , Pages 53-62
Abstract
In this paper, a multi-objective guidance scenario has been developed which could be used to improve the accuracy of sub-orbital modules at the entry to the earth’s atmosphere. Developed algorithm could be used for the trajectory shaping and adjusting of the trajectory relative to the desired position. ...
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In this paper, a multi-objective guidance scenario has been developed which could be used to improve the accuracy of sub-orbital modules at the entry to the earth’s atmosphere. Developed algorithm could be used for the trajectory shaping and adjusting of the trajectory relative to the desired position. To achieve defined objectives, it has been organized in three phases relative to different layers of trajectory. In the first phase, using of sensitivity functions which are of less computational burden, improving the accuracy according to the reference trajectory is done. In the second phase, trajectory shaping which is required to achieve desired flight performance is applied which could be designed and performed online in the mission. Finally in the last phase which is relative to low altitudes, improving of the accuracy according to homing rules is performed. Validation of developed algorithm using of a sample guidance problem is presented finally.
M. Mortazavi; D. Abbasi-Moghadam
Volume 3, Issue 2 , January 2011, , Pages 69-76
Abstract
هدف اصلی مقاله حاضر، هدایت بهینه و برخط اجسام بازگشتی به زمین است. روند دستیابی به این مهم مبتنی بر روش بسط مجانبی هماهنگ است که یکی از روش‌های خانوادة اغتشاشات تکین است ...
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هدف اصلی مقاله حاضر، هدایت بهینه و برخط اجسام بازگشتی به زمین است. روند دستیابی به این مهم مبتنی بر روش بسط مجانبی هماهنگ است که یکی از روش‌های خانوادة اغتشاشات تکین است و به کمک روش تغییر اکسترمالها تقویت شده است. روش جدید حاصل MAEOGکه مخفف کلمات مربوط به هدایت بهینة مبتنی بر بسط مجانبی هماهنگ است ضمن ارائة راه حل با دقت قابل قیاس با روش‌های دیگر، بسیار سریع مسئله را به جواب میرساند و زمان حل را کاهش میدهد. به علاوه، این امکان را میدهد که چه برا و چه زاویة رول به عنوان متغیرهای کنترل در نظر گرفته شوند. ویژگیهای روش جدید برای توسعة الگوریتم هدایتی بازگشت به زمین کاملاً مناسب به نظر میرسند.
