Browsing by Subject "Adaptive control allocation"

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Open Access
Controlling a launch vehicle at exoatmospheric flight conditions via adaptive control allocation
(Turkiye Klinikleri, 2020) Yıldız, Yıldıray
The focus of this paper is the control of a reusable launch vehicle at exoatmospheric flight conditions, in the presence of actuator effectiveness uncertainty. Since during exoatmospheric flight, dynamic pressure is nonexistent, aerodynamic control surfaces cannot be used. Under these conditions, reaction control jet actuators can provide the necessary thrust to control the vehicle. Reaction control jets have only 2 states, namely, on and off, and continuous control inputs can be implemented with the help of pulse width modulation, which is also employed in this paper. A continuous controller is designed in the outer loop and a control allocator is used to distribute the total control input among redundant actuators, whose effectiveness are assumed to be unknown. The unknown actuator effectiveness is addressed with the help of an adaptive control allocator. A representative model of a reusable launch vehicle equipped with reaction control jets is used to demonstrate the effectiveness of the overall control scheme.
Open Access
Integrated vehicle control using adaptive control allocation
(John Wiley & Sons Ltd., 2023-04-28) Temiz, Ozan; Çakmakçı, Melih; Yıldız, Yıldıray
The focus of this paper is an integrated, fault-tolerant vehicle control algorithm for the overall stability of ground vehicles. The proposed scheme comprises a high-level controller that creates a virtual control input and a low-level adaptive control allocator that distributes the virtual control effort among redundant actuators. The proposed control framework distinguishes itself from earlier results in the literature by its ability to blend active suspension, steering and traction control channels, in the presence of uncertainties and time-varying dynamics, without the need for fault identification. The control structure is validated in the simulation environment using a fourteen-degree-of-freedom non-linear vehicle model. The integrated controller is compared to the case of a conventional control approach where each control problem is solved separately. Our results show that, compared to the conventional approach, the proposed method ensures that the vehicle follows driver inputs with up to % higher longitudinal maneuver velocity, despite the presence of actuator failures and slippery road conditions. Furthermore, to demonstrate the benefit of integrating active suspension control to the overall control scheme, we replaced the suspension control of the proposed approach with an independent suspension control system for comparison purposes. We then showed that the integrated case provided % lower roll angle deviation, and % lower pitch angle deviation, in the presence of actuator effectiveness loss and adverse road conditions.