Nonlinear optimal controller design for nonlinear spacecraft formation flying with periodic coefficients via SDRE technique

2022 ◽  
Author(s):  
Ayansola D. Ogundele
Author(s):  
Hossein Rouzegar ◽  
Alireza Khosravi ◽  
Pouria Sarhadi

In this paper, spacecraft formation flying control under orbital perturbations by state-dependent Riccati equation method in the presence of on–off actuators is studied. Here, state-dependent Riccati equation is proposed as a more systematic and simple controller for solving the nonlinear problem of spacecraft formation flying in the leader–follower architecture. To create real conditions, the full nonlinear model of motion is considered while orbital perturbations are contained in the model. Also, to consider the operational conditions in controller design, on–off actuators are taken into account for the system. Due to the on–off nature of spacecraft thrusters, practical pulse-width pulse-frequency modulator is used for converting continuous signals to on–off pulses. Results are compared with other controllers to show the accuracy and performance of this method. In simulations, it is shown that the proposed controller as a new method has better performance confronting with the operational conditions including perturbations and on–off inputs. It is also shown that the energy consumption of the proposed controller is improved in comparison to other controllers.


2021 ◽  
Vol 11 (14) ◽  
pp. 6299
Author(s):  
Xiong Xie ◽  
Tao Sheng ◽  
Liang He

The distributed attitude synchronization control problem for spacecraft formation flying subject to limited energy and computational resources is addressed based on event-triggered mechanism. Firstly, a distributed event-driven controller is designed to achieve attitude coordination with the limitation of energy and computing resources. Under the proposed control strategy, the controller is only updated at the event triggering instants, which effectively reduces the update frequency. Subsequently, an event-triggered strategy is developed to further decrease energy consumption and the amount of computation. The proposed event-triggered function only requires the latest state information about its neighbors, implying that the trigger threshold does not need to be calculated continuously. It is shown that the triggering interval between two successive events is strictly positive, showing that the control system has no Zeno phenomenon. Moreover, the update frequency of the proposed controller can be reduced by more than 90% compared to the update frequency of the corresponding time-driven controller with an update frequency of 10 Hz by choosing appropriate control parameters and the control system can still achieve high-precision convergence. Finally, the effectiveness of the constructed control scheme is verified by numerical simulations.


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