S.H. Jalali Naini; Omid Omidi Hemmat
Abstract
In this study, the static and dynamic analyses of a modified integral pulse-width pulse-frequency (PWPF) modulator with small error-reset integrator (SE-RI) logical circuit are carried out using grid search method. A set of quasi-normalized equations is utilized in order to reduce the number of parameters, ...
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In this study, the static and dynamic analyses of a modified integral pulse-width pulse-frequency (PWPF) modulator with small error-reset integrator (SE-RI) logical circuit are carried out using grid search method. A set of quasi-normalized equations is utilized in order to reduce the number of parameters, that is, the integrator gain and the maximum torque of modulator are merged to other parameters. The output of the modified integral PWPF (IPWPF) modulator is limited to 50 Hertz.The preferred regions of the IPWPF are chosen by the amount of limitation on fuel consumption and thruster firings. These preferred regions are obtained for different dead zone values of SE-RI circuit. The analyses are performed in two methods with different choices of Schmitt-trigger parameters (i.e., hysteresis or threshold ratio). The proposed regions described by simple inequality relations represent the rectangular regions, which does not give the whole preferred region. As an advantage of the study, the preferred regions are presented graphically instead of rectangular regions by inequality relations.
S.Hamid Jalali -Naini; Sh. Ahmadi Darani
Volume 11, Issue 1 , June 2017
Abstract
In this paper, the preferred region of design parameters for quasi-normalized equations of single-axis attitude control of rigid spacecraft using pulse-width pulse-frequency modulator (PWPFM) is presented for rest-to-rest maneuvers. Using the quasi-normalized equations for attitude control reduces the ...
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In this paper, the preferred region of design parameters for quasi-normalized equations of single-axis attitude control of rigid spacecraft using pulse-width pulse-frequency modulator (PWPFM) is presented for rest-to-rest maneuvers. Using the quasi-normalized equations for attitude control reduces the system parameters, that is, the moment of inertia, the filter gain, and the maximum torque of modulator are merged to other parameters and the total number of parameters is reduced. Therefore, the computational burden is decreased and moreover, the results are usable for grouped parameters, regardless of the value of each parameter separately. The optimization is carried out by grid search method with the performance index of fuel consumption or number of thruster firings for a range of inputs. Finally, the suggested upper and lower bounds of parameters are obtained based on the optimization results.