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Sub-optimal ground-strike guidance based on perturbation method

An analytical guidance law based on perturbation method is proposed for ground strike mission. Letting the angle of attack (AOA) zero and considering the effects of gravity and drag force, the analytical expression of Zero Effort Miss (ZEM) is developed using perturbation method. In the development, the nonlinear flight dynamics is divided into the zeroth-order dynamics considering the major impact of gravity and drag force and the first-order dynamics compensating the remaining impact. To analytically solve the problem, an intermediate variable is innovatively introduced and some coefficients are fitted by Lagrange Polynomials. The simulation results show that the analytical ZEM expression has nearly the same high accuracy as the numerical integration, but the former has a much higher computation efficiency than the latter. Compared with the traditional guidance laws, the proposed guidance law can achieve a zero final AOA and requires less maneuvering load.