In this article, the event-triggered fixed-time tracking control is investigated for uncertain strict-feedback nonlinear systems involving state constraints. By employing the universal transformed function (UTF) and coordinate transformation techniques into backstepping design procedure, the proposed control scheme ensures that all states are constrained within the time-varying asymmetric boundaries, and meanwhile, the undesired feasibility condition existing in other constrained controllers can be removed elegantly. Different from the existing static event-triggered mechanism, a dynamic event-triggered mechanism (DETM) is devised via constructing a novel dynamic function, so that the communication burden from the controller to actuator is further alleviated. Furthermore, with the aid of adaptive neural network (NN) technique and generalized first-order filter, together with Lyapunov theory, it is proved that the states of closed-loop system converge to small regions around zero with fixed-time convergence rate. The simulation results confirm the benefits of developed scheme.

This paper studies the fixed-time control problem for the post-capture tethered spacecraft subject to full-state constraints and uncertainties. A C ¹ smooth adaptive fixed-time controller is constructed via introducing a smooth switch between fractional and quadratic form feedback, such that the undesired chattering and singularity issues are removed. With the aid of universal transformed function (UTF) technique, the proposed controller not only ensures that the constraint boundaries are not violated, but also eliminates the feasibility condition existing in the traditional barrier Lyapunov functions (BLFs)-based control solutions. Furthermore, by incorporating the generalized first-order filter and adaptive laws into control design procedure, the fixed-time stability of the closed-loop system can be guaranteed. The validity of the proposed control scheme is demonstrated by a simulation example.