In this paper, we address the problem of designing adaptive sliding mode controllers with guaranteed fixed-time convergence under disturbances. Based on the results in [1], we propose four adaptive approaches: the first is the classical adaptive method, the second incorporates a positive barrier function, and the third and fourth approaches rely on a class \(\mathcal {K}_\infty \) -function-based adaptive strategy. The aim is to avoid gain overestimation while ensuring a predefined convergence time without requiring knowledge of the disturbance bound. The main fixed-time stability properties of the proposed controllers are established using Lyapunov theory. Comparative simulation results and a practical transmission control protocol (TCP) tracking control example demonstrate the effectiveness of the approach in terms of robustness, bounded adaptation, and reduced chattering.
