Three-dimensional cooperative guidance law for intercepting hypersonic targets

This paper proposes a three-dimensional adaptive sliding mode cooperative guidance law using multiple low-speed interceptors with time-varying speeds for effectively intercepting hypersonic targets. The guidance commands are divided into commands along and normal to the line-of-sight (LOS). First, based on the algebraic graph and consensus theories, the guidance command along the LOS is designed to ensure that multiple interceptors achieve finite-time convergence to simultaneously intercept a hypersonic target. Second, to address the external disturbance caused by the manoeuvring of the hypersonic target in the direction normal to the LOS, finite-time disturbance observers are designed to accurately estimate the acceleration information of the hypersonic target with rapid convergence. Next, the guidance command normal to the LOS is formulated based on the sliding mode control method, which can nullify the LOS angular rate, ensuring progressive convergence to zero at interception. Moreover, thrust and drag models are incorporated to ensure that the guidance model is reasonably realistic. Numerical simulations are performed for different manoeuvring modes of the hypersonic target, and comparative simulations are conducted using the proportional navigation and sliding mode cooperative guidance laws. The simulation results demonstrate the superiority and effectiveness of the proposed guidance law.