A unified structure for basic guidance laws of moving objects

In this paper, it is shown that most guidance methods can be considered as a specific form of the cross-product steering law which is based on aligning two physical vectors along with each other, and the only difference between these guidance schemes is the pair of vectors that should be aligned during the guidance process. After verifying this fact, it is concluded that the angle between these aligning vectors can be considered as a sliding surface and based on this observation, a generalised guidance structure is proposed using the sliding mode control. This approach presents a unified strategy for analysing and implementing different guidance methods such as velocity-to-be-gained, pure pursuit, proportional navigation and path following. The main advantages of this structure are its generality and simple extension to the three-dimensional space. Finally, the superiority of the proposed approach to traditional strategies is demonstrated through simulation results.