An adaptive improved PD controller for rigid-elastic coupled launch vehicles

An improved proportional-derivative (PD) controller with adaptive capability is designed for the rigid-elastic coupled launch vehicle, aiming to achieve high-quality tracking of guidance instructions. The controller introduces an adaptive augmenting control (AAC) module, enhancing its parameter adjustment capabilities so that it can adaptively adjust both proportional and derivative coefficients simultaneously. Furthermore, an adaptive filter module is incorporated, with amplitude reduction complementing phase lag in the amplitude-phase characteristics of the transfer function. This filter adjusts its filtering effect adaptively based on the identification results of the elastic frequency. When applied to the pitch angle rate feedback channel, this filter effectively stabilizes the phase angle of the first-order elastic mode and the amplitude of the higher-order elastic mode. Numerical simulation results demonstrate that the designed adaptive improved PD controller not only has a simple structure and is easy to select parameters, but also exhibits excellent adaptive capabilities and significant elastic vibration suppression effects. Its remarkable engineering application value is demonstrated by its suitability for time-varying systems and its capacity to preserve system stability even in the presence of large model parameter variations.