A new three-dimensional guidance law based on reduced-order extended state observer for highly maneuvering targets

This paper proposes a new three-dimensional guidance law in order to achieve high-precision interception against the highly maneuvering targets in terminal guidance phase. Firstly, a reduced-order extended state observer is proposed to estimate the line-of-sight angle rate and the total disturbances composed of internal nonlinear dynamics and external disturbances. Secondly, a three-dimensional guidance law based on the reduced-order extended state observer is designed to actively compensate for the total disturbances and guarantee high-precision interception. The convergence and stability of the closed-loop interception system are analyzed rigorously. Different from the existing extended state observer based method, this paper only uses the line-of-sight angle as the output signal in the guidance law design. At the same time, the upper bounds of the system states are carefully analyzed to avoid the singularity of the closed-loop interception systems, which is not considered in existing results. Simulation results illustrate the effectiveness of the proposed method.