Nonsingular pliable prescribed performance tracking control for hypersonic flight vehicles in the presence of uncertainties and input saturation

Existing prescribed performance control methods encounter substantial challenges in effectively handling singularities under both actuator saturation and non-saturation conditions. In addition, current prescribed performance functions are highly sensitive to unknown initial tracking errors, which significantly restricts their applicability. To address these limitations, this article devises a novel and adaptable prescribed performance control scheme tailored for hypersonic vehicles, taking full account of system uncertainties and actuator saturation. Firstly, a pliable prescribed performance function (PPPF) is proposed. This function is capable of accommodating arbitrary initial tracking errors and achieving envelope adjustment independent of control input, thereby enhancing the control system’s adaptability to various initial conditions. Secondly, a new predefined-time convergence mechanism is developed and incorporated into the design of an anti-saturation compensator. This not only stabilizes the saturated system but also improves the convergence performance of auxiliary variable after the saturation subsides. Thirdly, a command filtered backstepping controller is designed for each subsystem of the hypersonic vehicle. In the altitude subsystem, the new convergence mechanism is extended to derive a predefined-time filter (PTF). Unlike existing filters, the PTF can offer superior tracking performance for filtered signals, further optimizing the overall control performance of the system. Finally, the effectiveness and superiority of the proposed control scheme are rigorously validated through numerical simulations and experiments conducted on a turntable servo system. The results demonstrate that the proposed method can significantly improve the control performance of the hypersonic vehicles under complex conditions, providing a reliable and efficient control solution for practical engineering applications.