Adaptive robust fault-tolerant control scheme for spacecraft proximity operations under external disturbances and input saturation

Observer-Based Adaptive Finite-Time Neural Control for Constrained Nonlinear Systems With Actuator Saturation Compensation

“…In each controller design procedure, the BLF is incorporated to ensure full the states are never violated and the tracking errors converge to the equilibrium in a finite time. However, the following drawbacks are worth considering: 1) we will focus on how to extend the presented strategy to solve time-varying state constraints instead of constant-state constraints; 2) although the Remark 7 gives a standard guideline for the selection of control parameters, another valuable topic is the study of optimization problems to determine optimal design parameters; and 3) the research of time-varying delays and actuator faults will be explored to improve the system safety and expand the application value in the spacecraft motion [18], [47], intelligent manufacturing [48]- [50], robotic systems [12], [35], etc.…”

“…Remark 1: Apart from the theoretical concerns, the system (1) is more general than the systems considered in [30], [40] due to the simultaneous consideration of external disturbances, actuator saturation, and full-state constraints. Moreover, many physical systems can be transformed into (1) by proper state transformations, such as mechanical manipulators [20], land vehicles [7], helicopters [39], spacecraft systems [18], etc.…”

“…Even though many conclusions have been developed to estimate the unavailable states, the convergence time cannot be reached as the time goes to finite. For this point, the control goal requires that the errors are close to the equilibrium when the time approaches infinity, such as the rigid spacecraft [18], quadrotor systems [19], and manipulators [20], etc. In [21], Bhat and Bernstein developed pioneering results in the finitetime control (FTC), which is a generalization for nonlinear systems that do not conform to the Lipschitz condition.…”

A Reference Governor with Adaptive Performance for Quadrotors under Safety Constraints

“…Furthermore, it contributes to reducing the computational complexity typically associated with fuzzy control methods. In [27], a method was introduced for adaptive robust fault-tolerant control in spacecraft proximity operations. Additionally, the tracking-control problem for small fixed-wing UAVs with input and state constraints was addressed in [28] through a robust approximation-free control strategy.…”

Improved Time-Varying BLF-Based Tracking Control of a Position-Constrained Robot

“…Smooth and continuous signals make it difficult for the system to generate excessive control inputs. In [48], a robust fault-tolerant control method is designed to deal with the adverse effect of the actuator saturation. The saturation nonlinearity is described by introducing a novel dead-zone model, and an adaptive method is used to compensate for the nondifferentiable integral term of the dead-zone model.…”