Model-Free Output Feedback Path Following Control for Autonomous Vehicle With Prescribed Performance Independent of Initial Conditions

Time-delay control (TDC) is widely recognized as a robust and straightforward model-free control approach for complex systems. However, the transient performance and settling time are often given less consideration in most TDC-based controllers. In this article, we propose an integrated control protocol that combines fixed-time prescribed performance control with time-delay estimation techniques for autonomous ground vehicles. The proposed control paradigm offers the advantages of being model-free while ensuring that the preview error converges to a neighborhood of zero within a fixed time, adhering to predefined constraint functions. To overcome the limitations of commonly used exponential decay boundaries, a prescribed performance function that remains independent of the initial conditions is employed. Furthermore, a high-order model-free fixed-time differentiator is constructed to observe the high-order dynamics of the preview error, which are essential for estimating unknown model dynamics. Finally, the simulations and practical experiments have been conducted to demonstrate the superiority of our proposed control protocol.