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.
Zahra Samadi Khoshkho; Mehdi Mortazavi-Bek; Farhad Fani Saberi
Volume 9, Issue 1 , May 2016, , Pages 47-56
Abstract
In this paper, an adaptive controller based on decentralized minimal control synthesis is designed n order to control an attitude of specific remote sensing satellite. The main design purposes are performing spinning, three axis and large angle maneuver as well as achieving a stable system and tracking ...
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In this paper, an adaptive controller based on decentralized minimal control synthesis is designed n order to control an attitude of specific remote sensing satellite. The main design purposes are performing spinning, three axis and large angle maneuver as well as achieving a stable system and tracking the reference attitude trajectory in the presence of uncertainties. In the design process, the effects of internal and external disturbances, nonlinearities in the satellite dynamic and the accurate model of actuators are regarded. Four reaction wheels with pyramidal structure are modeled as the actuators to accomplish an attitude maneuver. So the exact reaction wheels’ model with regarding the maximum voltage, current, allowable angular velocities and power of wheels is developed. The simulation results show an acceptable performance of controller in the presence of exacts actuators’ model, external and internal disturbances and uncertainties in the satellite parameters.
