M. Navabi; M. R Akhlomadi
Volume 8, Issue 3 , October 2015, , Pages 27-40
Abstract
In this paper a nonlinear optimal control is suggested. Spacecraft intended to rendezvous and dock with the target is controlled by actuators to have a safe and stable course while satisfying requirements. The Nonlinear optimal controller is designed using nonlinear equations of relative position and ...
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In this paper a nonlinear optimal control is suggested. Spacecraft intended to rendezvous and dock with the target is controlled by actuators to have a safe and stable course while satisfying requirements. The Nonlinear optimal controller is designed using nonlinear equations of relative position and attitude of spacecraft for circular and elliptical orbits with and without reaction wheels. Cost function of the optimal control problem is expressed in the form of nonlinear quadratic regulator and control constraints are applied to the problem to gain controls in the allowable domain which is produced by the wheels. For the sake of robustness to the uncertainties as one of the most important element of the control design, nonlinear optimal control is derived using state dependent Riccatti equation based on analytical method of eigen vectors of Hamiltonian matrix. Simulation results show that this nonlinear control method achieves a good performance for rendezvous and docking problem.
M. Navabi; M. Tavana; H.R. Mirzaei
Volume 7, Issue 4 , January 2015, , Pages 39-49
Abstract
Attitude control of spacecraft in order to nonlinear and high order dynamics is fundamental and challenging issue. With respect to these nonlinearities, linear control theories are not suitable choices and spacecraft may be unstable or lose performance. In this paper, State Dependent Riccati Equation ...
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Attitude control of spacecraft in order to nonlinear and high order dynamics is fundamental and challenging issue. With respect to these nonlinearities, linear control theories are not suitable choices and spacecraft may be unstable or lose performance. In this paper, State Dependent Riccati Equation (SDRE) method is utilized to 3-axis stabilization using four reaction wheels. State dependent Riccati equation method is systematic approach for optimal control of nonlinear systems which satisfies constraints of systems. In order to solve time consuming problem of this method in practical systems, Theta-D method is used. Results demonstrate the effectiveness of Theta-D in compare with Riccati method.
