Continuous reaching law based three-dimensional finite-time guidance law against maneuvering targets

Three-dimensional finite-time guidance laws are proposed in this paper. Differing from the traditional approach that considers homing guidance problems as two identical and perpendicular channels, guidance laws proposed in this paper employ the coupled three-dimensional engagement dynamics to improve the guidance precision. A new reaching law is adopted to guarantee guidance laws continuous, which eliminates the chattering phenomenon caused by discontinuous terms. Moreover, the guidance law accelerates the convergence rate of closed-loop systems and avoids the singularity. Afterwards, the paper discusses the problem that the upper bound of the lumped uncertainty including the target information is unavailable. Therefore, to deal with this problem, another adaptive guidance law is presented, which can also guarantee the finite-time convergence of guidance systems. Numerical simulations have demonstrated that the two guidance laws have effective performance and outperform traditional terminal sliding mode guidance laws.