Fixed‐time attitude tracking control for spacecraft based on adding power integrator technique

This work proposes a nonsingular adaptive fixed‐time switching control method for a class of strict‐feedback nonlinear dynamics subject to full state constraints. The peculiarity of this design lies in overcoming the singularity issue that typically appears in the existing backstepping‐based fixed‐time control methods caused by the iterative differentiation of fractional power terms as tracking errors approach to zero, while guaranteeing the nonviolation of full state constraints. Crucial in solving such singularity issue is to skillfully introduce a smooth switching between fractional power and integer power terms, which guarantees that fractional power term is confined within a positive interval all the time. An asymmetric time‐varying barrier Lyapunov function is delicately incorporated into control design, rendering state variables to be within prescribed time‐varying bounds. Besides, radial basis function neural network is employed to handle system unknown nonlinearities. It is rigorously proved that all the closed‐loop signals eventually converge to small regions around origin within fixed‐time. Comparative simulation results are finally given to validate the effectiveness and superiority of the proposed control strategy.

“…Moreover, there is just one point where its derivative is zero, so this stagnation point

c^{*} = {(α / β)}^{\frac{1}{q - p}}

must be the minimum point of the function and

T_{r} (c^{*}) \leq T_{r} (1)

Section: Problem Description and Preliminariesmentioning

confidence: 89%

Barrier Lypunov functions‐based nonsingular fixed‐time switching control for strict‐feedback nonlinear dynamics with full state constraints

Zhang

Dong

et al. 2021

“…The past decades have witnessed a rapid advance on theories of rigid‐body attitude control owing to its appealing advantages and fruitful applications in a broad range of areas, such as spacecraft, 1,2 unmanned aerial vehicles, 3,4 underwater vehicles 5,6 and so forth. The basic stabilization and tracking issues for rigid‐body attitude systems have been intensively addressed 7,8 and many fundamental results have been reported focusing on some problems, such as uncertainty, 4 actuator faults, 5 and state constraints 1,2 . Besides these issues, however, another benchmark issue to control a real‐world plant is also of concern, that is, guaranteeing a certain level of system performance, especially when the considered system is subject to some practical constraints such as control saturation.…”

Section: Introductionmentioning

confidence: 99%

Guaranteed cost control of rigid‐body attitude systems under control saturation

Wang

Yang

Liang

et al. 2021

This article investigates the guaranteed cost control (GCC) problem of nonlinear rigid‐body attitude systems subject to control saturation. A novel methodology is proposed, by which the nonlinearities inherent in the attitude dynamics are effectively accounted for and thereby the existence of the proposed controller is cast into linear/bilinear matrix inequality conditions without resorting to model linearization techniques. As a result, the underlying closed‐loop attitude system can be asymptotically stabilized by limited control effort and the defined cost function has an upper bound, by which four optimal GCC methods are further formed to minimize the cost index. Simulation results are provided that fully highlight the properties of the developed methodology in terms of cost guaranteeing and control effort limiting.

“…However, in the general case, the least upper bound for the convergence time is unknown, and close approximations are somewhat unavailable, leading to overestimations and larger control efforts. Pioneering applications of fixed‐time techniques can be found in References 21‐23.…”

Section: Introductionmentioning

confidence: 99%

Predefined‐time control of cooperative manipulators

Muñoz‐Vázquez

Sánchez‐Torres

2020

A cooperative controller that enforces an exact sliding motion in predefined-time, assuring cooperativeness, and stable manipulation, is proposed in this article. Alternatively, a continuous controller is also proposed, which induces in predefined-time that a hybrid force/position error converges into a predefined-bounded vicinity of the origin. Numerical simulations highlight the effectiveness of the proposed scheme.