Disturbance-observer-based attitude control under input nonlinearity

Abstract

A disturbance observer-based control scheme is proposed in this paper to deal with the attitude stabilization problems of spacecraft subjected to external disturbances, parameter uncertainties, and input nonlinearities. Particularly, the proposed approach addresses the dead-zone issue, a non-smooth nonlinearity affiliated with control input that significantly increases controller design difficulties. A novel nonlinear disturbance observer (NDO) is developed, which relaxes the strong assumption in conventional NDO design that disturbances should be constants or varying with slow rates. After that, a special integral sliding mode controller (ISMC) is combined with the NDO to achieve asymptotic convergence of system states. Simulations are performed in the presence of time-varying disturbances, parameter uncertainties, and dead-zone nonlinearity to justify the effectiveness of the proposed control scheme.

Robust adaptive attitude control of flexible spacecraft using a sliding mode disturbance observer

“…7 Similarly, a disturbance observer was used in Ref. 8, while an iterative learning observer was used for fault-tolerant control in Ref.11 for attitude control of spacecraft. Though observer-based control schemes improve the robustness of the system, the stability of the observer and controller are provided separately; however, the closed-loop system may still be unstable.…”

“…In recent years, various control techniques have been presented for attitude control of the spacecraft such as sliding mode control (SMC), 2,3 adaptive control, 4,5 passivity-based control, 6 and observer-based control. 7,8 However, the spacecraft encounters unpredictable disturbances in space and undergo parameter variations during mission operation elevating the difficulty in the controller design procedure. The tracking problem for the rigid body in the presence of external disturbances and model uncertainties has been discussed using SMC in Ref.…”

“…7 Similarly, a disturbance observer was used in Ref. 8, while an iterative learning observer was used for fault-tolerant control in Ref 11. for attitude control of spacecraft.…”

A novel adaptive-gain disturbance estimator-based asymptotic adaptive tracking control for uncertain nonlinear systems

“…Though the developed ESO has only one parameter to tune in practice applications, bounded control performance was achieved when facing time-variant disturbances. Nonlinear disturbance observer (NDO) presented in Javaid and Dong (2021) and Zhang et al (2020) and uncertainty and disturbance estimator (UDE) investigated in Ren et al (2020) were employed to estimate mismatched and matched disturbances simultaneously. But similar ESO, asymptotic tracking performance in Javaid and Dong (2021), Ren et al (2020) and Zhang et al (2020) could not be ensured while existing time-varying disturbances.…”

“…Nonlinear disturbance observer (NDO) presented in Javaid and Dong (2021) and Zhang et al (2020) and uncertainty and disturbance estimator (UDE) investigated in Ren et al (2020) were employed to estimate mismatched and matched disturbances simultaneously. But similar ESO, asymptotic tracking performance in Javaid and Dong (2021), Ren et al (2020) and Zhang et al (2020) could not be ensured while existing time-varying disturbances. Finite-time disturbance observer (FTDO) on basis of high-order sliding mode differentiators investigated in Liu et al (2020) was utilized to estimate the matched disturbance in finite time.…”