Composite Finite-time Guidance Law for Homing Missile

In this paper, the terminal guidance problem of a missile intercepting maneuvering target is studied. The main contributions are threefold. Firstly, a composite finite-time guidance law based on finite-time stability theory and nonlinear disturbance observer (NDOB) technique is proposed, which can effectively handle guidance system such that the missile intercepts a maneuvering target with zero miss distance. Secondly, with the help of NDOB, the switching gain of the composite guidance law only need to be chosen larger than the bounds of the target acceleration estimation error, which are usually much smaller than those of target acceleration. As a result, it is efficient to reduce the chattering phenomenon while the disturbance rejection performance of guidance system can well be maintained. The last but not least, a general class of finite-time guidance laws is proposed. The design method will become much more flexible and convenient. Finally, simulation results on missile-target interception example are provided to demonstrate the effectiveness of the proposed approaches.